Mathematical equation correction to spectral and transport interferences in high-resolution continuum source flame atomic absorption spectrometry: determination of lead in phosphoric acid

In this work, a new mathematical equation correction approach for overcoming spectral and transport interferences was proposed. The proposal was applied to eliminate spectral interference caused by PO molecules at the 217.0005 nm Pb line, and the transport interference caused by variations in phosphoric acid concentrations. Correction may be necessary at 217.0005 nm to account for the contribution of PO, since Atotal217.0005 nm = A Pb217.0005 nm + A PO217.0005 nm. This may be easily done by measuring other PO wavelengths (e.g. 217.0458 nm) and calculating the relative contribution of PO absorbance (A PO) to the total absorbance (Atotal) at 217.0005 nm: A Pb217.0005 nm = Atotal217.0005 nm - A PO217.0005 nm = Atotal217.0005 nm - k (A PO217.0458 nm). The correction factor k is calculated from slopes of calibration curves built up for phosphorous (P) standard solutions measured at 217.0005 and 217.0458 nm, i.e. k = (slope217.0005 nm/slope217.0458 nm). For wavelength integrated absorbance of 3 pixels, sample aspiration rate of 5.0 ml min-1, analytical curves in the 0.1 - 1.0 mg L-1 Pb range with linearity better than 0.9990 were consistently obtained. Calibration curves for P at 217.0005 and 217.0458 nm with linearity better than 0.998 were obtained. Relative standard deviations (RSD) of measurements (n = 12) in the range of 1.4 - 4.3% and 2.0 - 6.0% without and with mathematical equation correction approach were obtained respectively. The limit of detection calculated to analytical line at 217.0005 nm was 10 µg L-1 Pb. Recoveries for Pb spikes were in the 97.5 - 100% and 105 - 230% intervals with and without mathematical equation correction approach, respectively.

Effect of temperature, wetness duration and cultivar on the development of anthracnose in guava fruits

The development of a large number of postharvest diseases is closely associated with fruit ripeness. Environmental conditions may affect both the pathogen development and the fruit ripening rate. The aim of this study was to determine the most favorable temperature and wetness duration to the development of anthracnose in guava fruits. Cultivars 'Kumagai' (white pulp) and 'Pedro Sato' (red pulp) were inoculated with a conidial suspension of Colletotrichum gloeosporioides and C. acutatum and incubated at constant temperature ranging from 10 to 35ºC and wetness duration of 6 and 24 hours. Disease severity and incidence were evaluated at every two days during 12 days. No infection occurred at 10 and 35ºC, regardless of the wetness duration. The optimum conditions for fruit infection were 26 and 27ºC for 'Kumagai' and 25 and 26ºC for 'Pedro Sato', adopting 24 hours of wetness. In general, the disease development in 'Kumagai' cultivar was more affected by the wetness period, compared to 'Pedro Sato'. Disease severity for 'Kumagai' fruits was maximal between 25 and 30ºC , depending on the Colletotrichum species. Regarding 'Pedro Sato', the mean diameter of lesions was greater in fruits stored at 20, 25 and 30ºC , compared to 'Kumagai' cultivar, depending on the wetness period and the species. The incubation period (between 6 and 7 days) and the latent period (between 8 and 10 days) were minimal at 30ºC. The data generated in this study will be useful either for the development of a disease warning system or for the increase in the shelf life of guavas in the postharvest.

In vitro effect of substrate, temperature and photoperiod on Phakopsora pachyrhizi urediniospore germination and germ tube growth

In vitro experiments were conducted to assess the effects of substrate, temperature and time of exposure to temperature and photoperiod on P. pachyrhizi uredospore germination and germ tube growth. The following substrates were tested: water-agar and soybean leaf extract-agar at different leaf concentrations (0.5, 1.0, 2.0 and 4.0 g of leaves and 15g agar/L water), temperatures (10, 15, 20, 25, 30, and 35oC) and times of exposure (1, 2, 3, 4, 5, 6, 7, and 8 hours) to temperature and 12 different photoperiods. The highest germination and germ tube length was found for the soybean leaf extract agar. Maximum P. pachyrhizi uredospore germination was obtained at 21.8 and 22.3°C, and maximum germ tube growth at 21.4 and 22.1°C. The maximum uredospore germination was found at 6.4 hours exposure, while the maximum germ tube length was obtained at 7.7 h exposure. Regarding photoperiod, the maximum spore germination and the maximum uredospore germ tube length were found in the dark. Neither spore germination nor uredospore germ tube growth was completely inhibited by the exposure to continuous light.

Influence of temperature and leaf wetness duration in the severity of Cercospora leaf spot of beet

ABSTRACT In the present study, the influence of temperature (15, 20, 25, 30 and 35°C) and leaf wetness period (6, 12, 24 and 48 hours) on the severity of Cercospora leaf spot of beet, caused by Cercospora beticola, was studied under controlled conditions. Lesion density was influenced by temperature and leaf wetness duration (P<0.05). Data were subjected to nonlinear regression analysis. The generalized beta function was used for fitting the disease severity and temperature data, while a logistic function was chosen to represent the effect of leaf wetness on the severity of Cercospora leaf spot. The response surface resultant of the product of the two functions was expressed as ES = 0.0001105 * (((x-8)2.294387) * ((36-x)0.955017)) * (0.39219/(1+25.93072 * exp (-0.16704*y))), where: ES represents the estimated severity value (0.1); x, the temperature (ºC) and y, the leaf wetness duration (hours). This model should be validated under field conditions to assess its use as a computational forecast system for Cercospora leaf spot of beet.

TEMPERATURE AND SUBSTRATE INFLUENCES ON SEED GERMINATION AND SEEDLING FORMATION IN Callisthene fasciculata Mart. (VOCHYSIACEAE) IN THE LABORATORY1

ABSTRACTCallisthene fasciculata Mart. is a tree belonging to the Vochysiaceae family. Its wood is moderately heavy and resistant and used to make poles, beams, and other structures. The aim of this work was to evaluate seed germination and the initial growth of seedlings of C. fasciculata at different temperatures and in different substrates. Seeds were collected from fruits in the Pantanal de Miranda, Mato Grosso do Sul state, Brazil. In one experiment, the seeds were subjected to constant temperatures of 20, 25, 30 and 35 °C and to alternating temperatures of 20-30 and 25-35 °C (on paper substrate). In another experiment, the seeds were subjected to temperatures of 20 and 25 °C on three substrates (sand, vermiculite and between paper) in a germinator. The experiment had a randomized design, with four replicates of 25 seeds per treatment. The F-values obtained for germination indicated no significant effect of substrate or temperature on the final germination percentage. The analyses revealed no effect of a treatment interaction (temperature x substrate) on either germination or average germination time; however, a treatment interaction effect was observed on the germination speed index. The treatment combinations yielding the best performance were between paper substrate at 20 °C and sand substrate at 25 °C. There was a significant effect of the interaction between temperature and substrate on seedling growth, with increased root growth observed in the between paper substrate at 25 °C and increased aerial component growth in both sand at 20 °C and vermiculite at 25 °C. The between paper treatment at 25 °C yielded the greatest final seedling size. Between paper is the most recommended substrate for the production of seedlings due to its ease of handling and lower probability of contamination.

Temperature effect in potassium and nitrate ions in soil transport

When doing researches on solute dynamics in porous medium, the knowledge of medium characteristics and percolating liquids, as well as of external factors is very important. An important external factor is temperature and, in this sense, our purpose was determining potassium and nitrate transport parameters for different values of temperature, in miscible displacement experiments. Evaluated parameters were retardation factor (R), diffusion/dispersion coefficient (D) and dispersivity, at ambient temperature (25 up to 28 ºC), 40 ºC and 50 ºC. Salts used were potassium nitrate and potassium chlorate, prepared in a solution made up of 5 ppm nitrate and 2.000 ppm potassium, with Red-Yellow Latosol porous medium. Temperature exhibited a positive influence upon porous medium solution and upon dispersion coefficient.

Adjust of regression models to estimate the rectal temperature of broilers for the first 14 days of life

The broiler rectal temperature (t rectal) is one of the most important physiological responses to classify the animal thermal comfort. Therefore, the aim of this study was to adjust regression models in order to predict the rectal temperature (t rectal) of broiler chickens under different thermal conditions based on age (A) and a meteorological variable (air temperature - t air) or a thermal comfort index (temperature and humidity index -THI or black globe humidity index - BGHI) or a physical quantity enthalpy (H). In addition, through the inversion of these models and the expected t rectal intervals for each age, the comfort limits of t air, THI, BGHI and H for the chicks in the heating phase were determined, aiding in the validation of the equations and the preliminary limits for H. The experimental data used to adjust the mathematical models were collected in two commercial poultry farms, with Cobb chicks, from 1 to 14 days of age. It was possible to predict the t rectal of conditions from the expected t rectal and determine the lower and superior comfort thresholds of broilers satisfactorily by applying the four models adjusted; as well as to invert the models for prediction of the environmental H for the chicks first 14 days of life.

Use of data mining and spectral profiles to differentiate condition after harvest of coffee plants

This study aimed at identifying different conditions of coffee plants after harvesting period, using data mining and spectral behavior profiles from Hyperion/EO1 sensor. The Hyperion image, with spatial resolution of 30 m, was acquired in August 28th, 2008, at the end of the coffee harvest season in the studied area. For pre-processing imaging, atmospheric and signal/noise effect corrections were carried out using Flaash and MNF (Minimum Noise Fraction Transform) algorithms, respectively. Spectral behavior profiles (38) of different coffee varieties were generated from 150 Hyperion bands. The spectral behavior profiles were analyzed by Expectation-Maximization (EM) algorithm considering 2; 3; 4 and 5 clusters. T-test with 5% of significance was used to verify the similarity among the wavelength cluster means. The results demonstrated that it is possible to separate five different clusters, which were comprised by different coffee crop conditions making possible to improve future intervention actions.

Impact of elevated temperature scenarios on potato leaf development

The objective of this study was to simulate the impact of elevated temperature scenarios on leaf development of potato in Santa Maria, RS, Brazil. Leaf appearance was estimated using a multiplicative model that has a non-linear temperature response function which calculates the daily leaf appearance rate (LAR, leaves day-1) and the accumulated number of leaves (LN) from crop emergence to the appearance of the upper last leaf. Leaf appearance was estimated during 100 years in the following scenarios: current climate, +1 °C, +2 °C, +3 °C, +4 °C e +5 °C. The LAR model was estimated with coefficients of the Asterix cultivar in five emergence dates and in two growing seasons (Fall and Spring). Variable of interest was the duration (days) of the crop emergence to the appearance of the final leaf number (EM-FLN) phase. Statistical analysis was performed assuming a three-factorial experiment, with main effects being climate scenarios, growing seasons, and emergence dates in a completely randomized design using years (one hundred) as replications. The results showed that warmer scenarios lead to an increase, in the fall, and a decrease, in the spring growing season, in the duration of the leaf appearance phase, indicating high vulnerability and complexity of the response of potato crop grown in a Subtropical environment to climate change.

Detection of soybean planted areas through orbital images based on culture spectral dynamics

The soybean is important to the economy of Brazil, so the estimation of the planted area and the production with higher antecedence and reliability becomes essential. Techniques related to Remote Sensing may help to obtain this information at lower cost and less subjectivity in relation to traditional surveys. The aim of this study is to estimate the planted area with soybean culture in the crop of 2008/2009 in cities in the west of the state of Paraná, in Brazil, based on the spectral dynamics of the culture and through the use of the specific system of analysis for images of Landsat 5/TM satellite. The obtained results were satisfactory, because the classification supervised by Maximum Verisimilitude - MaxVer along with the techniques of the specific system of analysis for satellite images has allowed an estimate of soybean planted area (soybean mask), obtaining values ​​of the metrics of Global Accuracy with an average of 79.05% and Kappa Index over 63.50% in all cities. The monitoring of a reference area was of great importance for determining the vegetative phase in which the culture is more different from the other targets, facilitating the choice of training samples (ROIs) and avoiding misclassifications.

Thermal comfort temperature update for broiler chickens up to 21 days of age

Due to changes in genetics and nutrition, as well as in acclimatization of broiler chickens to the Brazilian climate, temperature values currently accepted as optimal may be outdated. The objective of this research was to update the environment temperatures that characterize the thermal comfort for broilers chickens from one to 21 days of age, under Brazilian production conditions. This research was conducted with 600 COBB birds, which were distributed in five growth chambers maintained at different temperatures during the first three weeks of age. During the experimental period, temperature values were progressively reduced, consisting in five treatments: T2724/21, T30/27/24, T33/30/27, T36/33/30 and T39/36/33. It was observed that the birds maintained in the T30(27-24) treatment presented better performance compared to other environment conditions. Based on the obtained regression models, the environment temperature values that provide greater weighing gain for the broiler chicken growth in the initial period were 31.3, 25.5 and 21.8 ºC, respectively for the first, second and third week of age.

Influence of data acquisition geometry on soybean spectral response simulated by the prosail model

View angle and directional effects significantly affect reflectance and vegetation indices, especially when daily images collected by large field-of-view (FOV) sensors like the Moderate Resolution Imaging Spectroradiometer (MODIS) are used. In this study, the PROSAIL radiative transfer model was chosen to evaluate the impact of the geometry of data acquisition on soybean reflectance and two vegetation indices (Normalized Difference Vegetation Index - NDVI and Enhanced Vegetation Index -EVI) by varying biochemical and biophysical parameters of the crop. Input values for PROSAIL simulation were based on the literature and were adjusted by the comparison between simulated and real satellite soybean spectra acquired by the MODIS/Terra and hyperspectral Hyperion/Earth Observing-One (EO-1). Results showed that the influence of the view angle and view direction on reflectance was stronger with decreasing leaf area index (LAI) and chlorophyll concentration. Because of the greater dependence on the near-infrared reflectance, the EVI was much more sensitive to viewing geometry than NDVI presenting larger values in the backscattering direction. The contrary was observed for NDVI in the forward scattering direction. In relation to the LAI, NDVI was much more isotropic for closed soybean canopies than for incomplete canopies and a contrary behavior was verified for EVI.

Spatial variability of air dry bulb temperature and black globe humidity index in a broiler house during the heating phase

The air dry-bulb temperature (t db),as well as the black globe humidity index (BGHI), exert great influence on the development of broiler chickens during their heating phase. Therefore, the aim of this study was to analyze the structure and the magnitude of the t db and BGHI spatial variability, using geostatistics tools such as semivariogram analysis and also producing kriging maps. The experiment was conducted in the west mesoregion of the states of Minas Gerais in 2010, in a commercial broiler house with heating system consisting of two furnaces that heat the air indirectly, in the firsts 14 days of the birds' life. The data were registered at intervals of five minutes in the period from 8 a.m. to 10 a.m. The variables were evaluated by variograms fitted by residual maximum likelihood (REML) testing the Spherical and Exponential models. Kriging maps were generated based on the best model used to fit the variogram. It was possible to characterize the variability of the t db and BGHI, which allowed observing the spatial dependence by using geostatistics techniques. In addition, the use of geostatistics and distribution maps made possible to identify problems in the heating system in regions inside the broiler house that may harm the development of chicks.

Influence of urbanization on land surface temperature in Recife city

Urbanization has caused significant environmental impacts, replacing natural surfaces by buildings, decreasing green vegetated areas, soil sealing and atmospheric pollution which contribute to increase the land surface temperature in such areas. Thus, this study aimed to analyze the influence of urbanization on land surface temperature (Ts) in Recife city - Pernambuco (PE), in Brazil, using the Thematic Mapper (TM) sensor images from Landsat 5 satellite. To perform the study, images of August 4, 1998 and September 6, 2010 were obtained and processed to generate Ts thematic maps of Recife-PE and of two districts of this city (Curado and Casa Amarela), in order to analyze the transformation dynamics that has occurred in the area. Through the profile produced for the study area, a spatial and temporal increase of the Ts surface was noticeable in the suburb-downtown direction: 6°C of difference between these areas. The Casa Amarela district, with high urban concentration, presented the highest Ts values observed (>27°C).

Effect of time-temperature binomial in obtaining biochemical oxygen demand of different wastewaters

Studies on the effects of temperature and time of incubation of wastewater samples for the estimation of biodegradable organic matter through the biochemical oxygen demand (BOD), that nowadays are rare, considering that the results of the classic study of STREETER & PHELPS(1925) have been accepted as standard. However, there are still questions how could be possible to reduce the incubation time; whether the coefficient of temperature (θ) varies with the temperature and with the type of wastewater and if it approaches 1.047. Aiming the elucidation of these questions, wastewater samples of dairy, swine and sewage treated in septic tanks were incubated at temperatures of 20, 30 and 35 °C, respectively for 5, 3.16 and 2.5 days. From the parameter of deoxygenation coefficient at 20 °C (k20), θ30 and θ35 were calculated. The results indicated that θ values changes with the type of wastewater, however does not vary in the temperature range between 30 and 35 °C, and that the use of 1.047 value did not implied significant differences in obtaining k in a determined T temperature. Thus, it is observed that the value of θ can be used to estimate the required incubation time of the samples at different temperatures.