DETERMINAÇÃO DO TEOR DE BIODIESEL EM DIESEL EMPREGANDO O ENSAIO COLORIMÉTRICO DO ÁCIDO HIDROXÂMICO

The aim of this paper was to use colorimetric assays for hydroxamic acid to quantify the biodiesel content in diesel and compare it with the traditional method (infrared spectroscopy, using the EN 14078 method). Samples were prepared from B2 to B10 with two kinds of diesel - S500 (red) and S50 (yellow) - to obtain two calibration curves. Through statistical methods it was shown that the slopes of the straight lines obtained for the different types of diesel were the same. Thus, the type of diesel did not influence the results of the colorimetric assay for hydroxamic acid. Real samples collected from gas stations were analyzed by both methods (colorimetry and EN 14078). By applying Student's t-test it was concluded that the methods could be considered statistically equivalent. Therefore, it was confirmed that the colorimetric assay for hydroxamic acid is suitable for detecting and quantifying the content of biodiesel in biodiesel/diesel blends and can also be easily adapted to field analyses.

SISTEMAS ALTERNATIVOS DE CALIBRAÇÃO PARA DETERMINAÇÃO ESPECTROFOTOMÉTRICA SIMULTÂNEA DE ESPÉCIES COM INTERFERÊNCIA ESPECTRAL

Two simple and efficient procedures have been developed for the rapid simultaneous determination of compounds with mutual spectral interference (rifampicin (RIF) and isoniazid (INH)). The first method was based on the UV–Vis spectral signal (190–600 nm) of synthetic RIF and INH aqueous solutions, whereas the second method involved the visible spectral signal registered between 350 and 800 nm after the reaction of INH with a Cu2+/neocuproine complex. Both multivariate spectrophotometric methods show excellent prevision capacity, providing results that are statistically equivalent with those provided by the standard chromatographic procedure. The methods were validated according to criteria established by ANVISA, showing precision, accuracy and robustness compatible with the requirements for new analytical methods, additionally allowing the reduction of waste generation.

Models and applications for risk assessment and prediction of Asian soybean rust epidemics

Asian rust of soybean [Glycine max (L.) Merril] is one of the most important fungal diseases of this crop worldwide. The recent introduction of Phakopsora pachyrhizi Syd. & P. Syd in the Americas represents a major threat to soybean production in the main growing regions, and significant losses have already been reported. P. pachyrhizi is extremely aggressive under favorable weather conditions, causing rapid plant defoliation. Epidemiological studies, under both controlled and natural environmental conditions, have been done for several decades with the aim of elucidating factors that affect the disease cycle as a basis for disease modeling. The recent spread of Asian soybean rust to major production regions in the world has promoted new development, testing and application of mathematical models to assess the risk and predict the disease. These efforts have included the integration of new data, epidemiological knowledge, statistical methods, and advances in computer simulation to develop models and systems with different spatial and temporal scales, objectives and audience. In this review, we present a comprehensive discussion on the models and systems that have been tested to predict and assess the risk of Asian soybean rust. Limitations, uncertainties and challenges for modelers are also discussed.

INFLUENTIAL FACTORS IN SURFACE WATER QUALITY IN CATCHMENTS WITHIN THE PAMPA BIOME WITH DIFFERENT LAND USE1

The aim of this study was to identify, by multivariate statistical technique, the physic, chemical and biological variables that best characterize the quality of surface waters in two small rural catchments with different land uses (eucalyptus silviculture (SC) vs. pasture and extensive livestock (LC)) located in Rosário do Sul, RS - Brazil. Monitoring was conducted during the months of August 2011 to August 2012 and the following parameters were analyzed: Ca2+, Mg2+, K+, SO42-, Cl-, pH, electrical conductivity, turbidity, alkalinity, suspended and dissolved solids, biochemical oxygen demand , total coliforms, Escherichia coli and temperature, flow and rainfall. Through the use of FA/PCA, it was found that the model best fit to express water quality of in LC that was composed of five factors which account for 83.5% of the total variance, while for SC, four factors accounted for 85.12% of the variance. In LC, the five main factors were, respectively, soluble salts, diffuse pollution, solid, and both anthropogenic and organic factors. In SC, the four factors were namely: soluble salts, mineral, nutritional and diffuse pollution factors. The results of this study showed that by replacing the traditional soil usage (pasture and livestock) with planted forest, diffuse pollution was attenuated but, however, it did not result in major changes in the physical-chemical and biological characteristics of the water. Another point to note is that factorial analysis did not result in a large reduction in the number of variables, once the best model fit occurred with the addition of 15 of 18 analyzed variables (LC) and 17 of 18 analyzed variables (SC).

Comparison of maps of spatial variability of soil resistance to penetration constructed with and without covariables using a spatial linear model

A study about the spatial variability of data of soil resistance to penetration (RSP) was conducted at layers 0.0-0.1 m, 0.1-0.2 m and 0.2-0.3 m depth, using the statistical methods in univariate forms, i.e., using traditional geostatistics, forming thematic maps by ordinary kriging for each layer of the study. It was analyzed the RSP in layer 0.2-0.3 m depth through a spatial linear model (SLM), which considered the layers 0.0-0.1 m and 0.1-0.2 m in depth as covariable, obtaining an estimation model and a thematic map by universal kriging. The thematic maps of the RSP at layer 0.2-0.3 m depth, constructed by both methods, were compared using measures of accuracy obtained from the construction of the matrix of errors and confusion matrix. There are similarities between the thematic maps. All maps showed that the RSP is higher in the north region.

Probabilistic structure of an annual extreme rainfall series of a coastal area of the State of São Paulo, Brazil

This study aimed to describe the probabilistic structure of the annual series of extreme daily rainfall (Preabs), available from the weather station of Ubatuba, State of São Paulo, Brazil (1935-2009), by using the general distribution of extreme value (GEV). The autocorrelation function, the Mann-Kendall test, and the wavelet analysis were used in order to evaluate the presence of serial correlations, trends, and periodical components. Considering the results obtained using these three statistical methods, it was possible to assume the hypothesis that this temporal series is free from persistence, trends, and periodicals components. Based on quantitative and qualitative adhesion tests, it was found that the GEV may be used in order to quantify the probabilities of the Preabs data. The best results of GEV were obtained when the parameters of this function were estimated using the method of maximum likelihood. The method of L-moments has also shown satisfactory results.

Management zones in agriculture acording to the soil and landscape variables

The study of spatial variability of soil and plants attributes, or precision agriculture, a technique that aims the rational use of natural resources, is expanding commercially in Brazil. Nevertheless, there is a lack of mathematical analysis that supports the correlation of these independent variables and their interactions with the productivity, identifying scientific standards technologically applicable. The aim of this study was to identify patterns of soil variability according to the eleven physical and seven chemical indicators in an agricultural area. It was used two multivariate techniques: the hierarchical cluster analysis (HCA) and the principal component analysis (PCA). According to the HCA, the area was divided into five management zones: zone 1 with 2.87ha, zone 2 with 0.8ha, zone 3 with 1.84ha, zone 4 with 1.33ha and zone 5 with 2.76ha. By the PCA, it was identified the most important variables within each zone: V% for the zone 1, CTC in the zone 2, levels of H+Al in the zone 4 and sand content and altitude in the zone 5. The zone 3 was classified as an intermediate zone with characteristics of all others. According to the results it is concluded that it is possible to separate into groups (management zones) samples with the same patterns of variability by the multivariate statistical techniques.

Shewhart's control charts and process capability ratio applied to a sewage treatment station

The current study used statistical methods of quality control to evaluate the performance of a sewage treatment station. The concerned station is located in Cascavel city, Paraná State. The evaluated parameters were hydrogenionic potential, settleable solids, total suspended solids, chemical oxygen demand and biochemical oxygen demand in five days. Statistical analysis was performed through Shewhart control charts and process capability ratio. According to Shewhart charts, only the BOD(5.20) variable was under statistical control. Through capability ratios, we observed that except for pH the sewage treatment station is not capable to produce effluents under characteristics that fulfill specifications or standard launching required by environmental legislation.

Physical attributes of a pasture soil in southeast Goiás determined by geostatistics

ABSTRACT This study aimed to evaluate the spatial dependence of physical attributes in a soil cultivated with Brachiaria grass. A 12-m regular sampling grid was established within an area of 3.500 m2. Thirty-five soil samples were collected at 0-30 cm depth for particle density, bulk density, texture and total porosity analysis. These data were evaluated using statistical methods of indicator kriging and the GS+ software. The GS+ software was used to develop three-dimensional maps and evaluate semivariograms. The spatial dependence was evaluated using experimental semivariograms. The analyzed attributes indicated the occurrence of spatial dependence when fit to the exponential model. Areas with higher porosity occurred in the regions with lower bulk densities and higher particle densities.

Histopathological diagnosis of intra- and extrahepatic neonatal cholestasis

The histopathology of the liver is fundamental for the differential diagnosis between intra- and extrahepatic causes of neonatal cholestasis. However, histopathological findings may overlap and there is disagreement among authors concerning those which could discriminate between intra- and extrahepatic cholestasis. Forty-six liver biopsies (35 wedge biopsies and 11 percutaneous biopsies) and one specimen from a postmortem examination, all from patients hospitalized for neonatal cholestasis in the Pediatrics Service of Hospital de Clínicas de Porto Alegre, were prospectively studied using a specially designed histopathological protocol. At least 4 of 5 different stains were used, and 46 hepatic histopathological variables related to the differential diagnosis of neonatal cholestasis were studied. The findings were scored for severity on a scale from 0 to 4. Sections which showed less than 3 portal spaces were excluded from the study. Sections were examined by a pathologist who was unaware of the final diagnosis of each case. Bile tract permeability was defined by scintigraphy of the bile ducts and operative cholangiography. The F test and discriminant analysis were used as statistical methods for the study of the hepatic histopathological variables. The chi-square method with Yates correction was used to relate the age of the patients on the date of the histopathological study to the discriminatory variables between intra- and extrahepatic cholestasis selected by the discriminant function test. The most valuable hepatic histopathological variables for the discrimination between intra- and extrahepatic cholestasis, in decreasing order of importance, were periportal ductal proliferation, portal ductal proliferation, portal expansion, cholestasis in neoductules, foci of myeloid metaplasia, and portal-portal bridges. The only variable which pointed to the diagnosis of intrahepatic cholestasis was myeloid metaplasia. Due to the small number of patients who were younger than 60 days on the date of the histopathological study (N = 6), no variable discriminated between intra- and extrahepatic cholestasis before the age of 2 months and all of them, except for the portal expansion, were discriminatory after this age. In infants with cholestasis, foci of myeloid metaplasia, whenever present in the liver biopsy, suggested intrahepatic cholestasis. Periportal ductal proliferation, portal ductal proliferation, portal expansion, cholestasis in neoductules, portal cholestasis and portal-portal bridges suggested extrahepatic obstructive cholestasis.

Dendritic thickness: a morphometric parameter to classify mouse retinal ganglion cells

To study the dendritic morphology of retinal ganglion cells in wild-type mice we intracellularly injected these cells with Lucifer yellow in an in vitro preparation of the retina. Subsequently, quantified values of dendritic thickness, number of branching points and level of stratification of 73 Lucifer yellow-filled ganglion cells were analyzed by statistical methods, resulting in a classification into 9 groups. The variables dendritic thickness, number of branching points per cell and level of stratification were independent of each other. Number of branching points and level of stratification were independent of eccentricity, whereas dendritic thickness was positively dependent (r = 0.37) on it. The frequency distribution of dendritic thickness tended to be multimodal, indicating the presence of at least two cell populations composed of neurons with dendritic diameters either smaller or larger than 1.8 µm ("thin" or "thick" dendrites, respectively). Three cells (4.5%) were bistratified, having thick dendrites, and the others (95.5%) were monostratified. Using k-means cluster analysis, monostratified cells with either thin or thick dendrites were further subdivided according to level of stratification and number of branching points: cells with thin dendrites were divided into 2 groups with outer stratification (0-40%) and 2 groups with inner (50-100%) stratification, whereas cells with thick dendrites were divided into one group with outer and 3 groups with inner stratification. We postulate, that one group of cells with thin dendrites resembles cat ß-cells, whereas one group of cells with thick dendrites includes cells that resemble cat a-cells.

Manual and semi-automatic quantification of in vivo ¹H-MRS data for the classification of human primary brain tumors

In vivo proton magnetic resonance spectroscopy (¹H-MRS) is a technique capable of assessing biochemical content and pathways in normal and pathological tissue. In the brain, ¹H-MRS complements the information given by magnetic resonance images. The main goal of the present study was to assess the accuracy of ¹H-MRS for the classification of brain tumors in a pilot study comparing results obtained by manual and semi-automatic quantification of metabolites. In vivo single-voxel ¹H-MRS was performed in 24 control subjects and 26 patients with brain neoplasms that included meningiomas, high-grade neuroglial tumors and pilocytic astrocytomas. Seven metabolite groups (lactate, lipids, N-acetyl-aspartate, glutamate and glutamine group, total creatine, total choline, myo-inositol) were evaluated in all spectra by two methods: a manual one consisting of integration of manually defined peak areas, and the advanced method for accurate, robust and efficient spectral fitting (AMARES), a semi-automatic quantification method implemented in the jMRUI software. Statistical methods included discriminant analysis and the leave-one-out cross-validation method. Both manual and semi-automatic analyses detected differences in metabolite content between tumor groups and controls (P < 0.005). The classification accuracy obtained with the manual method was 75% for high-grade neuroglial tumors, 55% for meningiomas and 56% for pilocytic astrocytomas, while for the semi-automatic method it was 78, 70, and 98%, respectively. Both methods classified all control subjects correctly. The study demonstrated that ¹H-MRS accurately differentiated normal from tumoral brain tissue and confirmed the superiority of the semi-automatic quantification method.

Reference value of brachial-ankle pulse wave velocity for the eastern Chinese population and potential influencing factors

The present study was conducted to obtain reference values for brachial-ankle pulse wave velocity (baPWV) and to evaluate influencing factors of baPWV according to gender. Using automatic devices, baPWV was measured simultaneously in 2095 subjects. A total of 647 healthy subjects, none of whom presented atherosclerotic risk factors, were analyzed in the present study. Two different statistical methods were used to obtain reference values for baPWV according to subject gender and age. The association between baPWV value and gender, as well as other features, were analyzed. For male subjects, multiple stepwise analysis showed that age, systolic blood pressure (SBP), heart rate (HR), and plasma levels of triglycerides (TG) were independent predictors of baPWV. For female subjects, age, SBP, HR, and plasma levels of uric acid (UA) were independent predictors of baPWV. In male subjects, the upper limits of baPWV values were 1497.43/1425.00, 1518.67/1513.25, 1715.97/1726.50, 1925.20/1971.90, and 2310.18/2115.00 cm/s, obtained using two different statistical methods for the age ranges of 30-39, 40-49, 50-59, 60-69, and 70 and older, respectively. For females, the upper limits of baPWV values were 1426.70/1411.13, 1559.15/1498.95, 1733.50/1739.00, 1958.63/1973.78, and 2720.80/2577.00 cm/s for the age ranges of 30-39, 40-49, 50-59, 60-69, and 70 and older, respectively. Aging is the most important influencing factor for baPWV value and its effect is more prominent in females. The reference values of baPWV according to age and gender may be useful for the clinical diagnosis and preventive therapy of cardiovascular diseases.

Characterization of commercial cooked hams according to physicochemical, sensory, and textural parameters using chemometrics

Cooked ham is considered a high-value product due to the quality of its raw material. Although its consumption is still low in Brazil, it is increasing due to the rising purchasing power of sectors of the population. This study aimed to assess the microbiological, physicochemical, rheological, and sensory quality of cooked hams (n=11) marketed in Brazil. All samples showed microbiological results within the standards established by Brazilian legislation. Eight of the eleven samples studied met all the legal requirements; two samples violated the standards due to the addition of starch; one sample had lower protein content than the minimum required, and another one had sodium content higher than that stated on the label. The use of Hierarchical Cluster Analysis allowed the agglomeration of the samples into three groups with distinct quality traits and with significant differences in moisture content, chromaticity, syneresis, and heating and freezing loss. Principal Component Analysis showed that the samples which correlated to higher sensory acceptance regarding flavor and overall acceptability were those with higher moisture, protein, fat, and luminosity values. This study confirmed the efficacy of multivariate statistical techniques in assessing the quality of commercial cooked hams and in indicating the physicochemical parameters associated with the perception of product quality.

Characterization of the phenolic and antioxidant profiles of selected culinary herbs and spices: caraway, turmeric, dill, marjoram and nutmeg

Culinary herbs and spices have long been considered essentially as flavor enhancers or preservatives, with little attention given to their potential health-promoting properties. Nevertheless, recent research has shown them to be significant dietary sources of bioactive phenolic compounds. Despite noteworthy efforts performed in recent years to improve our knowledge of their chemical composition, a detailed phenolic profile of these plant-based products is still lacking. In the present work, antioxidant activities and phenolic composition of five herbs and spices, namely caraway, turmeric, dill, marjoram and nutmeg, have been studied. The use of liquid chromatography coupled to LTQ-Orbitrap mass spectrometry enabled the identification of up to 42 phenolic compounds. To the best of our knowledge, two of them, apigenin-C-hexoside-C-pentoside and apigenin-C-hexoside-C-hexoside have not been previously reported in turmeric. Qualitative and quantitative differences were observed in polyphenol profiles, with the highest phenolic content found in caraway. Multivariate statistical treatment of the results allowed the detection of distinctive features among the studied herbs and spices.