224 resultados para Espectroscopia de reflectância difusa


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Fibromyalgia (FM) is a non-inflammatory rheumatic syndrome characterized by widespread musculoskeletal pain with palpable tender points, muscle stiffness, fatigue, and sleep disturbances. Patients with FM have hormonal changes that are directly correlated with symptoms of the syndrome. The neuroendocrine regulation may be impaired, with abnormalities in the hypothalamus-pituitary-adrenal (HPA) axis with various hormones showing changes in their levels. In women in fertile period, various gonadal hormones are associated with symptoms of the syndrome, but studies focusing only a population of women in post-menopausal period who do not use hormone replacement are rare. We developed an analytical cross sectional study to assess the plasma levels of cortisol and dehidroepiandrosterona sulfate (DHEA-S) with quimioluminescence method in a group of 17 women with FM and 19 healthy women in post-menopause who do not use hormone replacement and observe the correlation with the symptoms of pain through algometry, depression and physical functional capacity measured from the Beck Depression Index (BDI) and the Fibromyalgia Impact Questionnaire (FIQ). Three blood samples were collected in the morning (between 8:00 9:30) with an interval of 24 hours for the measurements of hormonal levels and biochemical profile. There were no immunological or lipid changes in patients with FM. Comparing the two groups, there is no difference in levels of cortisol and a tangential effect for DHEA-S (p=0,094) with the lowest levels in the FM. DHEA-S also correlated with pain threshold (r=0,7) and tolerance (r=0,65) in group FM. We found the presence of depressive state and low physical functional capacity in FM. It was also evident that women in post-menopausal period, DHEA-S should influence the symptoms of increased sensitivity to pain, but not the presence of depressive status and low physical functional

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The object of this study was to identify the possibility of predicting the involvement in traffic infractions from the results of the psychological tests carried out by psychologists specialized in the process of driver licensing in the state of Rio Grande do Norte (RN). The proposal consisted in identifying the penalty points recorded in national driving licenses (CNH) and identifying the corresponding tests and scores obtained, verifying if the average scores in the tests of drivers with and without an infraction record were significantly different and if there is any relation between the test scores and the frequency of the infractions. The results of the psychological instruments were collected in two moments the first being in the act of acquisition of the CNH and the second being during license renewal at the only certified clinic and at the DETRAN-RN. A population of 839 drivers of 14 municipalities were identified. 127 protocols of psychological tests were identified in the records of the DETRAN-RN (2002) and 76 at the clinic (2007), pointing out failures in the process of safekeeping of the psychological material, as well as in its retrieval from the record files. The sample was thus reduced to 68 drivers, all male, with age range between 18 and 41 years old, mean of 21,72 years old (DP = 5,24). 54 drivers were identified without a record of infraction, and 14 with a record. The latter committed 29 infractions. The penalty points recorded in their CNH ranged from 0 to 35 and the typical value of points (median) was zero. In the group with a record of infractions the number of points ranged between 3 and 35, mean of 10,79 (DP = 7,73). Differences were observed in the composition of the battery of tests in the two moments with the same subjects. The use of different tests to assess the same construct of the subject, first and second moment of assessment, did not allow for some analyzes with more efficient statistical proof. It was pointed out that five tests were not carried out and 118 were not corrected/analyzed. Significant differences between the groups were not identified with the psychological instruments used. In another attempt to establish differences between the means, the application of the independent t-Test evidenced a significant difference in the scores of the instruments of concentrated attention in 2002 (t = 2,21, gl = 25, p = 0.037) and of diffuse attention in 2002 (t = 2,37, gl = 24, p = 0.026). The results also did not evidence significant correlation between the scores of the tests and the penalty points of the infractions. Based on this study, it cannot be concluded with precision that the high or low scores are good criteria to determine that a driver will commit more or less traffic infractions, nor that the drivers with higher scores in the tests commit less infractions and vice-versa. Furthermore, the problems to find the instruments and the most basic data require a stronger monitoring on the part of the certified clinic and of the DETRAN-RN.

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The metalic oxides have been studies due to differents applications as materials semiconductor in solar cells, catalysts, full cells and, resistors. Titanium dioxide (TiO2) has a high electric conductivity due to oxygen vacancies. The Ce(SO4)2.2H2O doped samples TiO2 and TiO2 pure was obtained sol-gel process, and characterized by X-ray diffractometry,thermal analysis, and impedance spectroscopy. The X-ray diffraction patterns for TiO2 pure samples shows at 700°C anatase phase is absent, and only the diffraction peaks of rutile phase are observed. However, the cerium doped samples only at 900°C rutile in the phase present with peaks of cerium dioxide (CeO2). The thermal analysis of the TiO2 pure and small concentration cerium doped samples show two steps weight loss corresponding to water of hydration and chemisorbed. To larger concentration cerium doped samples were observed two steps weight loss in the transformation of the doped cerium possible intermediate species and SO3. Finally, two steps weight loss the end products CeO2 and SO3 are formed. Analyse electric properties at different temperatures and concentration cerium doped samples have been investigated by impedance spectroscopy. It was observed that titanium, can be substituted by cerium, changing its electric properties, and increased thermal stability of TiO2 anatase structure

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Perovskite-like ceramic materials present the general formula ABO3, where A is a rare earth element or an alkaline metal element, and B is a transition metal. These materials are strong candidates to assume the position of cathode in Solid Oxide Fuel Cells (SOFC), because they present thermal stability at elevated temperatures and interesting chemical and physical properties, such as superconductivity, dieletricity, magnetic resistivity, piezoelectricity, catalytic activity and electrocatalytic and optical properties. In this work the cathodes of Solid Oxide Fuel Cells with the perovskite structure of La1-xSrxMnO3 (x = 0.15, 0.22, 0.30) and the electrolyte composed of zirconia-stabilized-yttria were synthesized by the Pechini method. The obtained resins were thermal treatment at 300 ºC for 2h and the obtained precursors were characterized by thermal analysis by DTA and TG / DTG. The powder precursors were calcined at temperatures from 450 to 1350ºC and were analyzed using XRD, FTIR, laser granulometry, XRF, surface area measurement by BET and SEM methods. The pellets were sintered from the powder to the study of bulk density and thermal expansion

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Chitosan derivatives were prepared by reductive alkylation using glutaraldehyde and 3-amino-1-propanol. The reducing agent used was the sodium borohydride. Tests of solubility, stability and viscosity were performed in order to evaluate these parameters effects in the reaction conditions (molar ratio of the reactants and presence of nitrogen in the reaction system). The molecular structure of commercial chitosan was determined by infrared (IR) and hydrogen nuclear magnetic resonance spectroscopy (1H NMR). The intrinsic viscosity and average molecular weight of the chitosan were determined by viscosimetry in 0.3 M acetic acid aqueous solution 0.2 M sodium acetate at 25 ºC. The derivatives of chitosan soluble in aqueous acidic medium were characterized by 1H NMR. The rheological behavior of the chitosan and of the derivative of chitosan (sample QV), which presented the largest viscosity, were studied as a function of polymer concentration, temperature and ionic strength of the medium. The results of characterization of the commercial chitosan (the degree of deacetylation obtained equal 78.45 %) used in this work confirmed a sample of low molar weight (Mv = 3.57 x 104 g/mol) and low viscosity (intrinsic viscosity = 213.56 mL/g). The chemical modification of the chitosan resulted in derivatives with thickening action. The spectra of 1H NMR of the soluble derivatives in acid aqueous medium suggested the presence of hydrophobic groups grafted into chitosan in function of the chemical modification. The solubility of the derivatives of chitosan in 0.25 M acetic acid aqueous solution decreased with increase of the molar ratio of the glutaraldehyde and 3-amino-1-propanol in relation to the chitosan. The presence of nitrogen and larger amount of reducing agent in reaction system contributed to the increase of the solubility, the stability and the viscosity of the systems. The viscosity of the polymeric suspensions in function of the shear rate increased significantly with polymer concentration, suggesting the formation of strong intermolecular associations. The chitosan presented pseudoplastic behavior with the increase in polymer concentration at a low shear rate. The derivative QV presented pseudoplastic behavior at all concentrations used and in a large range of shear rate. The viscosity of chitosan in solution decreased with an increase of the temperature and with the presence of salt. However, there was an increase of the viscosity of the chitosan solution at higher temperature (65 ºC) and ionic strength of the medium which were promoted by hydrophobic associating of the acetamide groups. The solutions of the chitosan derivatives (sample QV) were significantly more viscous than chitosan solution and showed higher thermal stability in the presence of salt as a function of the hydrophobic groups grafted into chitosan backbone

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Due to environmental restrictions around the world, clean catalytic technology are of fundamental importance in the petrochemical industry and refineries. Creating the face of this a great interest in replacing the liquid acids for solid acids, so as molecular sieves have been extensively studied in reactions involving the acid catalysis to produce chemical substances with a high potential of quality. Being the activity of the catalysts involved in the reaction attributed to the acid character of them involved for the Lewis and Brönsted acid sites. Based on this context, this study aimed to prepare catalysts acids using a molecular sieve silicoalumino-phosphate (SAPO-11) synthesized in hidrotermical conditions and sulphated with sulphuric acid at different concentrations, using to it the method of controlled impregnating. The samples resulting from this process were characterized by x-ray difratometry (DRX), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermal analysis (TG-DTG) and determination of total acidity (by n-butilamin adsorption). The results show that the synthesis method used was efficient in the formation of AEL structure of SAPO-11 and when being incorporated the sulfate groups in this structure the acidity of the material was increased, pointing out that to very high concentrations of acid there is a trend of decrease the main peaks that form the structure. Finally they were tested catalytictly by the reaction model of conversion of m-xylene which showed favorable results of conversion for this catalyst, showing to be more selective of cracking products than isomerization, as expected, in order that for the o-xylene selectivity there was no positive change when to sulfate a sample of SAPO-11, while for light gases of C1-C4 this selectivity was remarkably observed

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Heterogeneous catalysts such as aluminophosphate and silicoaluminophosphate, molecular sieves with AEL of ALPO-11 and SAPO-11, were synthesized by the hydrothermal method with the following molar composition: 2.9 Al +3.2 P + 3.5 DIPA +32.5 H20 (ALPO-11); 2.9 Al +3.2 P + 0.5 Si + 3.5 DIPA +32.5 H20 (SAPO-11) starting from silica (only in the SAPO-11), pseudoboehmite, orthophosphoric acid (85%) and water, in the presence of a di-isopropylamine organic template. The crystallization process occurred when the reactive hydrogel was charged into a vessel and autoclaved at 170ºC for a period of 48 hours under autogeneous pressure. The obtained materials were washed, dried and calcined to remove the molecular sieves of DIPA. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), thermo gravimetric differential thermal analysis (TG/DTA) and nitrogen adsorption (BET). The acidic properties were determined using adsorption of n-butylamine followed by programmed thermodessorption. This method revealed that ALPO-11 has weaker acid sites due to structural defects, while SAPO-11 shows an acidity that ranges from weak to moderate. However, a small quantity of strong acid sites could be detected there. The deactivation of the catalysts was conducted by the cracking of the n-hexane in a fixed bed continuous flow microrreator coupled on line to a gas chromatograph. The main products obtained were: ethane, propane, isobutene, n-butane, n-pentane and isopentane. The Vyazovkin (model-free) kinetics method was used to determine the regeneration and removal of the organic template

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Films of chitosan with trivalent lanthanides ions Eu3+ and Tb3+ were respectively prepared in the ratio of 3:1 m/m (chitosan: lanthanide) and 6:1 m/m (chitosan: lanthanide). There were no formations of films in a ratio of 1:1 m/m (chitosan: lanthanides). The films of chitosan with the Tb3+ ion have the same transparent appearance than the pure chitosan films. The film of chitosan with Eu3+ ion has a muddy appearance. These films present good resistance to tear. The appearance of the compounds prepared in ratio 1:1m/m is a white powder. The films and compounds of chitosan were characterized by Elementary Analysis (CHN), Thermal Analysis (TG/DTG) and Spectroscopy of Luminescence. The CHN analysis was made only for compounds prepared in ratio 1:1m/m, suggesting that these compounds possess the formula QUILn.6H2O, where QUI = Chitosan and Ln = Lanthanide. The results of the curves TG/DTG indicated that there are strong interactions between Eu3+ or Tb3+ and chitosan, causing a lesser lost of mass in the films. The luminescence analysis showed that the films of chitosan with the ions Eu3+ and Tb3+ present emissions in the region of the visible one, with bands of the chitosan and of the Eu3+ ion. The luminescence analysis of the compounds of chitosan with the Eu3+ and Tb3+ ions suggest that the chitosan does not transfer into energy to the ions lanthanides, however the chemical neighborhood around of the ion lanthanides breaks the selection rules and, conseqüently the 4f-4f transitions of the lanthanide ions are observed

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The study of sediment in water bodies presents great environmental importance, because of its ability to adsorb the pollutants, they may facilitate the understanding of the history of the current quality of the water system. Depending on how it is done the collection, analysis can show both a recent contamination as old. The detailed characterization of the sediment may reveal details that can understand how each type of pollutant interacts with the material given its composition. In this work it has developed a systematic methodology to characterize samples of sediment, with the aim to understand how a series of metal is distributed in different size fractions of the sediment. This study was conducted in five samples of sediment (P1, P2, P3a, P3B and P3c) collected in Jundiaí river, one of the most important tributaries of the river Potengi in the region of Macaíba, RN. The characterization was made with the samples previously sieved into meshes with different granulometries (+8#, -8+16#, -16+65# - 65+100#,-100+200#,-200+250# and -250#), using the following techniques: Analysis of specific surface area by BET method, determining the levels of organic matter (OM%) and humidity through the gravimetry and Analysis Thermogravimetric (TG), Infrared Spectroscopy in a Fourier transform (FTIR ), Analysis of X ray diffraction (XRD), analysis of heavy metals by optical emission spectrometry with the Argon Plasma (ICP-OES). The analyzed elements were Al, Cd, Cr, Cu, Fe, Mn, Ni, Zn and P. In addition to the techniques of characterization above, was also made the rebuilding of the samples P1, P2 and P3B in relation to the levels of organic matter and concentration of heavy metals. Then, the results of the recomposed samples were compared with those obtained in crude samples, showing great consistency. The gravimetry, used in determining the levels of organic matter, was not considered an appropriate method because the clay minerals present in the sediment samples analyzed fall apart in the same range of temperature (550-600 0C) used in roasting (600 0C). The results also showed the trend of organic matter and heavy metals to focus on the thin fractions, although the largest concentrations of metals are in intermediate fractions

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In this paper, the Layered Double Hydroxides (LDH s) type hydrotalcite were synthesized, characterized and tested as basic heterogeneous catalysts for the production of biodiesel by transesterification of sunflower oil with methanol. The synthesis of materials Layered Double Hydroxides (LDH s) by co-precipitation method from nitrates of magnesium and aluminum, and sodium carbonate. The materials were submitted to the variation in chemical composition, which is the amount of Mg2+ ions replaced by Al3+. This variation affects the characteristic physico-chemical and reaction the solid. The molar ratio varied in the range of 1:1 and 3:1 magnesium / aluminum, and their values between 0.2 and 0.33. This study aims to evaluate the influence of variation of molar ratio of mixed oxides derived from LDH s and the influence of impregnation of a material with catalytic activity, the KI, the rate of conversion of sunflower oil into methyl esters (biodiesel) through transesterification by heterogeneous catalysis. .The catalysts were calcined at 550 ° C and characterized by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy of X-ray (SEM / EDS), thermogravimetric analysis (TG) and test basicity. The transesterification reaction was performed for reflux is a mixture of sunflower oil and methanol with a molar ratio of 15:1, a reaction time of 4h and a catalyst concentration of 2% by weight. The physical-chemical characterization of sunflower oil and biodiesel obtained by the route methyl submitted according NBR, EN, ASTM. Subsequently, it was with the chromatographic and thermogravimetric characterizations of oils. The results of chromatographic analysis showed that the catalysts were effective in converting vegetable oil into biodiesel, in particular the type hydrotalcite KI-HDL-R1, with a conversion of 99.2%, indicating the strong influence of the chemical composition of the material, in special due to presence of potassium in the structure of the catalyst

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In this work the organosilanes aminopropyltriethoxysilane, 3-mercaptopropyltryethoxisilane and n[-3-(trimetoxisilyl)propyl]ethylenetriamine, as well as tetraethylortosilicate (TEOS), were employed to produce, by sol-gel method, organofuncionalized silicon samples. The prepared samples were characterized by elementar analys by thermogravimetry and infrared spectroscopy. Those samples were employed to adsorb Cd2+, Pb2+, Ni2+ and Zn2+ from aqueous solutions (10, 20, 40, 60 and 80 mg L-1). In typical experiments, 50 mg of the organometrix was suspended in 20 mL of metal cation solutions at four different contact times: 30, 60, 90 and 120 minutes. The total amount of adsorbed cations were measured by atomic absorption spectrometry. To all investigated matrices, the following adsorption capacity was observed: Ni2+ > Zn2+ > Cd2+ > Pb2+. Such sequence is closely related with the cation radius, as well as the cation hardness

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This study aimed to analyze the effect of a saline solution on growth and chemical composition of Atriplex nummularia, shrubby plant, absorbing salts used in the diet of animals and the management of water and saline soils. These plant seedlings were planted and grown in a reserved area at the Federal University of Rio Grande do Norte. The plantation was divided into two blocks, in which one of them was irrigated with saline solution with a concentration of 2840 mgL-1 of NaCl and the second group was irrigated with drinking water. After six months, the plants were collected, harvested and divided into three parts: leaf, thin and thick stem. Monthly, dimension measurements were carried out for cataloging the growth of Atriplex. Ion Chromatography (IC) and Optical Emission Spectroscopy Inductively Coupled Plasma (ICP-OES) were used to analyze the chemical composition of the partition plant parts. The results of these analyses revealed that an absorption process of anions and cations by Atriplex nummularia plant during its growth was achieved, in particular by a higher concentration of sodium and chloride ions. Scanning electron microscopy images showed and confirmed the presence of small crystals on the leaf surface. Electrical conductivity and pH measurements of the aerial parts of the plant were carried out and these results showed that the leaf is the plant part where there is a largest concentration of ions. In addition, measurements of specific surface were obtained from irrigated plants with saline solution, achieving higher surface area, in all cases. Plant dimensions obtained monthly showed that the plants irrigated with water grew 5% more than those plants irrigated with saline solution. Based on results obtained, Atriplex plant showed a higher potential to survive and adapt to environments (aquatic or geological) with high levels of salinity and this property can be used as a tool for removing salts/metals from industrial contaminated soils and effluents.

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Tendo em vista a grande biodiversidade existente no litoral brasileiro, onde muitas espécies ainda são pouco conhecidas, inclusive sob o aspecto nutricional, e considerando que os moluscos bivalves se constituem em um recurso natural de boa aceitação pela população mundial, escolheu-se o molusco bivalve Anadara notabilis, por não ter sido encontrado na literatura nenhuma informação nutricional ou toxicológica sobre ele e devido seu tamanho ser bem maior que outras espécies de moluscos mais popularmente encontrados nessa região. Foram determinados neste trabalho teores de umidade, cinzas, proteínas, macro e microminerais, além de íons metálicos de importância toxicológica. Todas as determinações seguiram as Normas Analíticas do Instituto Adolfo Lutz. A determinação de proteína foi realizada pelo método de Kjeldahl. Todos os íons metálicos foram determinados por espectroscopia de emissão ótica com plasma indutivamente acoplado (ICP-OES) descrito pela metodologia USEPA 6010C. Os resultados mostraram que a Anadara notabilis pode ser introduzida na alimentação dos seres humanos, tendo em vista sua riqueza mineral. Merecem destaque entre os macronutrientes o magnésio e o fósforo que apresentaram os respectivos valores em mg/kg 918,7 e 586,7. Com relação aos micronutrientes destacam-se o ferro presente com 586,7 mg/kg e o Zinco com 12,31 mg/kg. Não foi encontrado índice elevado de metais contaminantes para este molusco, o que impediria seu consumo, apenas o cromo esta 0,7 mg/kg acima do valor estabelecido pela legislação brasileira. Os resultados obtidos certamente serão muito úteis em futuras pesquisas nutricionais e para construção de uma tabela brasileira de composição química de alimentos

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Given the large existing biodiversity in the Brazilian coast, where many species are still little known, even under the nutritional aspect, and considering that bivalve molluscs are constituted by a natural resource of well accepted by the population, chose the bivalve Anadara notabilis, it was not found in the literature any nutritional or toxicological information about it and because its size is much larger than other species of mollusks commonly found in this region. Were studied moisture, ash, protein, macro and micro minerals, and metal ions of toxicological significance. All analytical determinations followed the standards of the Institute Adolfo Lutz. The protein determination was performed by the Kjeldahl method. All metal ions were determined by optical emission spectroscopy with inductively coupled plasma (ICP-OES) method described by USEPA 6010C. The results showed that Anadara notabilis can be introduced into food for human beings, in view of its mineral wealth. Noteworthy among the macronutrients phosphorus and magnesium showed that their values in mg / kg 918.7 and 586.7. With regard to micronutrients stand out with this iron 586.7 mg / kg and zinc with 12.31 mg / kg. Was not found high content of metal contaminants to this mollusc, which would prevent their use, only this chromium 0.7 mg / kg above the value established by Brazilian legislation. The results will certainly be very useful in future studies of nutrition and to build a table of chemical composition of Brazilian foods

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Polycyclic aromatic hydrocarbons (PAHs) constitute a family of compounds characterized by having two or more condensed aromatic rings and for being a class of substances that are widely distributed in the environment as a complex mixture, being very persistent in the environment due to its low solubility in water. The application of chemometric methods to analytical chemistry has provided excellent results in studying the solubility of PAHs in aqueous media in order to understand the mechanisms involved in environmental contamination. The method consists in analyzing the solubilization of PAHs from diesel oil in water varying parameters such as stirring time, volume of oil added and pH, using a full factorial design of two levels and three factors. PAHs were extracted with n-hexane and analyzed by fluorescence spectroscopy because they have molecular characteristics fluorescent due to the large number of condensed rings and links, and gas chromatography coupled to a mass spectrometer (GC-MS). The results of fluorescence analysis showed that only the stirring time and pH influenced the solubility of PAHs in diesel fuel. How is a non-selective technique for the study of fluorescence was performed on form and semi-quantitative. And for the chromatographic analysis the results showed that the solubility of the different PAHs is influenced differently so that you can classify them into groups by the results of the effects