8 resultados para air minimum temperature

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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Background In the last 20 years, there has been an increase in the incidence of allergic respiratory diseases worldwide and exposure to air pollution has been discussed as one of the factors associated with this increase. The objective of this study was to investigate the effects of air pollution on peak expiratory flow (PEF) and FEV1 in children with and without allergic sensitization. Methods Ninety-six children were followed from April to July, 2004 with spirometry measurements. They were tested for allergic sensitization (IgE, skin prick test, eosinophilia) and asked about allergic symptoms. Air pollution, temperature, and relative humidity data were available. Results Decrements in PEF were observed with previous 24-hr average exposure to air pollution, as well as with 310-day average exposure and were associated mainly with PM10, NO2, and O3 in all three categories of allergic sensitization. Even though allergic sensitized children tended to present larger decrements in the PEF measurements they were not statistically different from the non-allergic sensitized. Decrements in FEV1 were observed mainly with previous 24-hr average exposure and 3-day moving average. Conclusions Decrements in PEF associated with air pollution were observed in children independent from their allergic sensitization status. Their daily exposure to air pollution can be responsible for a chronic inflammatory process that might impair their lung growth and later their lung function in adulthood. Am. J. Ind. Med. 55:10871098, 2012. (c) 2012 Wiley Periodicals, Inc.

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Cementitious pastes prepared with air-entraining admixtures (AEA) are very sensitive to mix procedures and environmental conditions. Some of the effects of AEA on the properties of cementitious material are discussed in literature, although for the most part, only in the hardened state. However, the impact temperature has on air-incorporation during the early age stages and on consolidation has been little investigated and as such, is the objective of this work. Thus, pastes formulated with Portland cement and air-entraining admixtures are evaluated in this work with a focus on the role temperature plays in the early age behavior. The results show that air-incorporation was affected by environmental conditions which caused changes in the kinematic viscosity and rate of consolidation.

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Lianas play a key role in forest structure, species diversity, as well as functional aspects of tropical forests. Although the study of lianas in the tropics has increased dramatically in recent years, basic information on liana communities for the Brazilian Atlantic Forest is still scarce. To understand general patterns of liana abundance and biomass along an elevational gradient (0-1,100 m asl) of coastal Atlantic Forest, we carried out a standard census for lianas a parts per thousand yen1 cm in five 1-ha plots distributed across different forest sites. On average, we found a twofold variation in liana abundance and biomass between lowland and other forest types. Large lianas (a parts per thousand yen10 cm) accounted for 26-35% of total liana biomass at lower elevations, but they were not recorded in montane forests. Although the abundance of lianas displayed strong spatial structure at short distances, the present local forest structure played a minor role structuring liana communities at the scale of 0.01 ha. Compared to similar moist and wet Neotropical forests, lianas are slightly less abundant in the Atlantic Forest, but the total biomass is similar. Our study highlights two important points: (1) despite some studies have shown the importance of small-scale canopy disturbance and support availability, the spatial scale of the relationships between lianas and forest structure can vary greatly among tropical forests; (2) our results add to the evidence that past canopy disturbance levels and minimum temperature variation exert influence on the structure of liana communities in tropical moist forests, particularly along short and steep elevational gradients.

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The effects of drying air inlet temperature (IT) and concentration of Aerosil 200 (C-A) on several properties of spray-dried Apeiba tibourbou extracts were investigated following a 3(2) full factorial design. Powder recovery varied from 9.83 to 46.95% and dried products showed moisture contents below 7%. Although the spray-dried products lost some of their polyphenols, they still present excellent antioxidant activity, opening perspectives for its use to medicinal purpose. C-A exerted a key role on the properties of spray-dried extracts, while IT did not present a significative influence. Aerosil (R) 200 proved to be an interesting alternative as an excipient for the drying of the herbal extract, even at intermediate concentrations such as 15%. The best combination of conditions to use for obtaining dry A. tibourbou extracts with adequate physicochemical and functional properties involves an IT of 100 degrees C and a C-A of 15%.

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In this work, we correlate the daily number of human leptospirosis cases with several climatic factors. We used a negative binomial model that considers hospital daily admissions due to leptospirosis as the dependent variable, and the climatic variables of daily precipitation pattern, and maximum and minimum temperature as independent variables. We calculated the monthly leptospirosis admission probabilities from the precipitation and maximum temperature variables. The month of February showed the highest probability, although values were also high during the spring months. The month of February also showed the highest number of hospital admissions. Another interesting result is that, for every 20 mm precipitation, there was an average increase of 31.5% in hospital admissions. Additionally, the relative risk of leptospirosis varied from 1.1 to 2.0 when the precipitation varied from 20 to 140 mm.

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Known as the "king of spices", black pepper (Piper nigrum), a perennial crop of the tropics, is economically the most important and the most widely used spice crop in the world. To understand its suitable bioclimatic distribution, maximum entropy based on ecological niche modeling was used to model the bioclimatic niches of the species in its Asian range. Based on known occurrences, bioclimatic areas with higher probabilities are mainly located in the eastern and western coasts of the Indian Peninsula, the east of Sumatra Island, some areas in the Malay Archipelago, and the southeast coastal areas of China. Some undocumented places were also predicted as suitable areas. According to the jackknife procedure, the minimum temperature of the coldest month, the mean monthly temperature range, and the precipitation of the wettest month were identified as highly effective factors in the distribution of black pepper and could possibly account for the crop's distribution pattern. Such climatic requirements inhibited this species from dispersing and gaining a larger geographical range.

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The aim of this study was to investigate the improvement of the aqueous solubility of carbamazepine by preparing microstructured ternary solid dispersions using polyoxylglycerides and colloidal silicon dioxide. Microstructured solid dispersions were obtained in a spray dryer. The influence of the spray drying conditions on the properties of the microparticles was investigated using a full 3(2) factorial design in which the factors studied were the silicon dioxide content and the air outlet temperature. The microparticles were thoroughly characterized in terms of yield, solubility, angle of repose, particle size, drug content, moisture content, sorption isotherms, morphology, thermal behavior, infrared spectroscopy and crystallinity. The dissolution rates of carbamazepine and of the microparticles in water were also determined. In general, the microstructured solid dispersions demonstrated good yield, adequate flow and moisture content (<3%), drug recovery (91.98 to 100.22%) and particle size (<142.90 mu m). Thermal and infrared analysis showed that there was no drug interaction during the process. On the other hand, the results of X-ray diffraction evidenced a partial polymorphic modification of carbamazepine. The solubility and dissolution rates of carbamazepine were remarkably improved. Therefore, the results confirm the high potential of the spray drying technique to obtain microstructured ternary solid dispersions. (C) 2011 Elsevier B.V. All rights reserved.

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A presença de aditivos incorporadores de ar (AIA) em suspensões cimentícias torna esses materiais sensíveis às etapas de processamento e às condições ambientais de preparo das composições. Diversos estudos têm sido reportados em literatura avaliando o efeito de incorporadores de ar nas propriedades de materiais cimentícios, sobretudo no estado endurecido. Porém o efeito da temperatura na incorporação de ar e nas propriedades reológicas dessas composições tem sido menos investigado, sendo este o objetivo do presente trabalho. Para tanto, foram avaliadas as características de pastas cimentícias, compostas por cimentos CPIIF ou CPIIE e dois tipos de AIA, em função da variação da temperatura. O conceito de viscosidade cinemática foi adotado na análise dos resultados para compensar diferenças de inércia das pastas com densidades distintas. Os resultados mostraram que o tipo de cimento, a presença do aditivo e a temperatura influenciaram significativamente na incorporação de ar e nas propriedades reológicas.