951 resultados para Cobalt Radioisotopes
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Urban growth of metropolitan areas has produced impacts of considerable importance on environment and water resources. Such impacts are in general associated with human activities, such as basin area uncontrolled development. In this context, Pitimbu river watershed, located at Natal metropolitan area, has been affected by uncontrolled development caused by urban expansion. Indeed, such effects have been reflected on water quantity and quality, which may produce social consequences. Pitimbu river is an important water supplier for human consumption, actually supplying a 2600 m3/h water discharge. This study aims to analyze the qualitative and quantitative aspects of water and sediment on Pitimbu river lowland portion. For this purpose, physical-chemical water properties were analyzed, and sediment macro invertebrates benthonic were monitored in two cross sections in a period between November 8th, 2007 and October 3rd, 2008. Monitoring methodology consisted of water and sediment sampling for laboratory analysis. Water quality analysis included Dissolved Oxygen, Oxygen Biochemical Demand, Nitrate, pH and Alkalinity, Suspended and Total Solids. The analysis of heavy metals in the sediment included Cadmium, Cobalt, Copper, Chrome, Silver and Nickel. Dry season water discharge data were measured and used to adjust recession function parameters, whose values reveal quick recession and strong river-aquifer unconfined interaction. Water quality analysis revealed the absence of degradation by organic composites. However, DO and BOD levels indicate that more consistent results could be provided if sampling time interval were reduced. Biomonitoring showed signs of aquatic ecosystem degradation by the absence of sensitive and abundance of resistant benthic organisms. Obtained results demonstrate the urgent need of effective management measures to provide environmental protection. The increase of environmental degradation will certainly make impracticable the use of water for human consumption
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Oral and facial bone defects can undertake appearance, psychosocial well-being and stomathognatic function of its patients. Over the yerars several strategies for bone defect regeneration have arised to treat these pathologies, among them the use of frozen and irradiated bone allograft. Manipulation of bone grafts it s not determined yet, and several osteotomy alternatives can be observed. The present work evaluated with a microscope the bone fragments obtained from different osteotomy methods and irrigation on rings and blocks allografts irradiated and frozen at 80° negative in a rabbit model. The study is experimental in vitro and it sample was an adult male New Zealand rabbit. The animal was sacrificed to obtain long bones, that were submitted to freezing at 80º negative and irradiated with Cobalt- 60. Then the long bones were sectioned into 24 bone pieces, divided into 4 groups: G1 (n=06) osteotomy was performed with bur No. 6 forming rings with 5 mm thickness with high-speed handpiece with manual irrigation; G2 (n=06) osteotomy was performed with bur No. 6 forming rings with 5 mm thick with surgical motor with a manual irrigation rotation 1500 rpm; GA (n=06), osteotomy with trephine using manual irrigation with saline; and GB (n=06), osteotomy with trephine using saline from peristaltic pumps of surgical motor. Five bone pieces of each group were prepared for analysis on light microscopy (LM) and one on electronic scan electronic microscopy (SEM). On the SEM analysis edges surface, presence of microcracks and Smear Layer were evaluated. Analyzing osteotomy technics on SEM was observed: increased presence of microcracks cutting with high speed; increased presence of areas covered by Smear Layer when cutting with motor implant. The irrigation analysis with SEM was observed: that the presence of microcracks does not depend on the type of irrigation; on manual irrigation, there was greater discrepancy between the cutting lines. The descriptive analysis of the osteotomy and irrigation process on LM showed: histological analysis showing the bony margins with clear tissue changed layer, composed of blackened tissue of charred appearance near to the cortical bone; on the edges of the bony part, bone fragments that were displaced during the bone cut and bone irregularities were observed. After analysis of results we can conclude: that there was greater regularity of the bone cut using high-speed handpiece than using motor implant; the cut with trephine using saline irrigated from peristaltic pumps of surgical motor showed greater homogeneity when compared with manual irrigation; charred tissue was found in all obtained bone samples, whit no significant statistically difference on the proportion of carbonization of the two analysed technics
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The isotherms of adsorption of MeX2 (Me = Cu2+, Co2+; X = Cl-, Br-, ClO4-) by silica gel chemically modified with 2-mercaptoimidazole (SiMI) were studied in acetone and ethanol solutions, at 25 degrees C. Covalently attached 2-mercaptoimidazole molecule to silica gel surface adsorbs MeX2 from solvent by forming a surface complex. The metal is bonded to the surface through the nitrogen atom of attached 2-mercaptoimidazole. At low loading, the electronic and ESR spectral parameters indicated that the Cu2+ complexes are in a distorted-tetragonal symmetry field. The d-d electronic transition spectra showed that for Cu(ClO4)(2) complex, the peak of absorption did not change for any degree of metal loading and for Cl- and Br- complexes, the peak maxima shifted to higher energy with lower metal loading. The CoX2(X = Cl-, Br-, ClO4-) analogues possess a distorted-tetrahedral field.
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This study aims to determine the amount of nutrients and toxic elements in aquatic macrophytes of species Eichhornia crassipes present in River Apodi/Mossoró - RN and check some of the possibilities of using the biomass produced, based on the influence of space - temporal and physiological absorption of nutrients by plants. For this, was determined: Leaf area, Leaf wet mass, Leaf dry mass, Real humidity, Apparent humidity, Ash, Total nitrogen, Crude protein, Calcium, Magnesium, Potassium, Total phosphorus, Sodium, Iron, Copper, Manganese, Zinc, Nickel, Cobalt, Aluminum, Cadmium, Lead and Total chromium at different times, 2 sampling points and 2 parts of plants (leaves and roots). The results show that the levels of nutrients, protein and toxic elements present in plant tissue of Eichhornia crassipes are influenced by spatial, temporal and physiological variability. In general, because the maximum values in the dry matter for total nitrogen (4.4088 g/100g), crude protein (27.5549 g/100g), total phosphorus (0.642 g/100 g), calcium (1.444 g/100g), magnesium (0.732 g/100 g), potassium (7.51 g/100 g), copper (4.4279 mg/100g), manganese (322.668 mg/100g), sodium (1.39 g/100g), iron (194.169 mg/100g) and zinc (3.5836 mg/100g), there was the possibility of using biomass of Eichhornia crassipes for various purposes such as in food animal, products production for human consumption, organic fertilizers, fabrication of brick low cost, and crafts. For all these applications requires a control of the levels of substances in plant tissue. Based on the levels of nutrients and crude protein, the younger plants (0 Month) would be best to have their biomass used. Moreover, one factor that contributes to the use of larger plants (6 Months), the levels of toxic elements which have significantly small or below the detection limit. Therefore, further studies quantifying the biomass produced/m2 at 0 and 6 months are needed for a more correct choice for the best time of harvest
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In recent years, studies about the physicochemical properties of mixed oxides, call attention of the scientific community, properties like as piezoelectricity, photoluminescence, or applications as catalysts, arise in these compounds, when their chemical compositions are modified, in this context some routes are employed in the synthesis of these materials, among which can be cited these methods: ceramic, combustion, co-precipitation, Pechini or polymeric precursor method, hydrothermal, sol-gel; these routes are divided into traditional routes or chemical routes. In this work were synthesized oxides with variable composition, from the thermal decomposition of titanium, cobalt, nickel and praseodymium nitrilotriacetates. The nitrilotriacetates were characterized by IR Spectroscopy (FTIR), Thermogravimetric (TG/ DTG) and Differential Scanning Calorimetry (DSC), while oxides have been characterized by X-ray diffraction (XRD), Spectrofluorimetry and IR Spectroscopy (FTIR). From FTIR data, it was demonstrated that the displacement of the band corresponding to the carboxylate group (νCOOH) at 1712 cm-1, present in nitrilotriacetic acid (H3NTA), for 1680-1545 cm-1, these stretches are characteristics of coordinated nitrilotriacetates, By thermal analysis (TG/DTG /DSC), it was suggested, that in an oxidizing atmosphere (air) oxides are obtained at lower temperatures than in an inert atmosphere N2(g). By results from X-ray Diffraction (XRD), it was determinated that the oxides are crystalline and the predominant phases obtained are summarized titanate phases rutile and ilmenite. By fluorimetry was observed that the intensity of emission bands are directly proportional to the concentration of ions Ni2+, Co2+ and Pr3+, and IR spectroscopy (FTIR) from oxides, demonstrated the disappearance of characteristic bands by nitrilotriacetates, determining the complete decomposition of the nitrilotriacetates in oxides
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The present work was to carry out a study on the adsorption of hydrogen sulfide (H2S) in arrays synthesized from a commercial clay mineral formed by a mixture of dolomite and quartz. To produce the ion exchange matrix were made using aqueous solutions of salts of cobalt II chloride hexahydrate (CoCl2.6H2O) II cadmium nitrate tetrahydrate (Cd (NO3)2.4H2O) I mercuric chloride (HgCl) nitrate and chromium III pentahydrate (Cr (NO3)3.5H2O). The arrays were subjected to hydrogen sulphide gas passage for one hour. To check the amount of gas adsorbed was used gravimetric process. The best result was in the adsorption matrix doped with cadmium and the solution retained for a longer time than the largest amount of H2S was the cobalt matrix. The matrix unmodified exhibited poor adsorption capacity. The characterization of the matrices were used XRD, XRF and IV. Mother with cadmium showed a high capacity in ion exchange, because the percentage of cadmium increased from 0% to 81.38% by replacing atoms of calcium and silicon which increased from 96.54% to 17.56% and 15, 72% to 0.32%, respectively, but also the best performance in adsorption of H2S adsorbing 11.89507 mg per gram of matrix
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This work involved the synthesis, characterization and proposing the molecular structure of coordination compounds involving ligands pyrazine-2-carboxamide (PZA) and 4- hydrazide acidic pyridine carboxylic (INH) and metals of the first transition series (M = Co2+, Ni2+ and Cu2+). For the characterization of the compounds used were analytical techniques such as infrared absorption spectroscopy average (FT-IR) molar conductivity measurements, CHN elemental analysis, EDTA Complexometric, measurement of melting point, X-ray diffraction by powder method, Thermogravimetry (TG) and Differential Thermal Analysis (DTA) and Simultaneous Differential Scanning Calorimetry (DSC). The absorption spectra in the infrared region suggested that the ligand coordination to the metal center occurs through the carbonyl oxygen atom and nitrogen alpha pyrazine ring to those complexes formed with PZA. For INH complexes with metal-ligand coordination is through the carbonyl oxygen and nitrogen of the terminal hydrazide grouping. The conductivity measurements of the complexes in aqueous solution they suggest to all behavior of the type 1:2 electrolytes, and conduct of non-electrolytes in acetonitrile. The results obtained by CHN elemental analysis and EDTA Complexometric allowed to infer the stoichiometry of the compounds synthesized. For all of the complexes obtained was possible to record the melting points, neither of which melted near the melting temperature of the free ligands. The X-ray diffraction showed that the complexes of pyrazinamide exhibited diffraction lines, suggesting that these compounds are crystalline, while compounds of isoniazid, with the exception of cobalt, exhibited diffraction lines, indicating that they are crystalline. The results from the TG-DTA and DSC allowed information regarding the dehydration and thermal decomposition of these complexes
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Two pillaring methods were tested to synthesize pillared clays containing mixed Al/Co pillars. Using the first method, based on the traditional procedure, were obtained materials containing different Co concentrations: 10, 25, 50, 75 and 100 % of Co in the pillaring solution. Just the experiments with low concentrations (10 and 25 % of Co) has formed pillared clays, whereas the sample with 25 % of cobalt showed best results compared with the one obtained just using Al as pillaring agent (basal spacing higher than 18 Å and surface area bigger than 300 m²/g). The 27Al NMR results pointed out the formation of mixed Al/Co pillars due to decreased between the intensities of AlVI/AlIV signals, indicating that the AlIV content decreased while Co content increased, suggesting the isomorphic substitution of Al atoms for Co in the Keggin ion structure (pillaring agent). For the samples containing 75 and 100 % of cobalt, it was verified the formation of others materials, which could be identified as hydrotalcite like compounds. The second pillarization method was named mixed layers, because the objective was to intercalate clay layers with hydrotalcite layers. Thus, after calcination, the hydrotalcite layers would dehydroxylate, resulting just in the metals oxides, intercalated between the clay sheets, thus generating, a pillared clay. For this purpose, were tested 4 synthesis procedures: physical mixture, mixture in water, ionic exchange under reflux and in situ synthesis. Of these, the method which showed the best results was the in situ synthesis, in which basal spacings of 14 Å (after calcination) were obtained, indicating that the samples are intercalated with metal oxides (Mg and Al). This procedure was reproduced with a Co-Al LDH (layered double hydroxide) and similar results were obtained, testifying the method reproducibility
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The ferrite composition Ni1 - xCoxFe2O4 (0 ≤ x ≤ 0.75) were obtained by the method of microwave assisted synthesis and had their structural and magnetic properties evaluated due to the effect of the substitution of Ni by Co. The compounds were prepared: according to the concept of chemical propellants and heated in the microwave oven with power 7000kw. The synthesized material was characterized by absorption spectroscopy in the infrared (FTIR), Xray diffraction (XRD) using the Rietveld refinement, specific surface area (BET) , scanning electron microscopy (SEM) with aid of energy dispersive analysis (EDS) and magnetic measurements (MAV). The results obtained from these techniques confirmed the feasibility of the method of synthesis employed to obtain the desired spinel structure, the ferrite, nickel ferrite as for nickel doped with cobalt. The results from XRD refinement ally showed the formation of secondary phases concerning stages α - Fe2O3, FeO, (FeCo)O e Ni0. On the other hand, there is an increase in crystallite size with the increase of cobalt in systems, resulting in an increased crystallinity. The results showed that the BET systems showed a reduction in specific surface area with the increase of cobalt and from the SEM, the formation of irregular porous blocks and that the concentration of cobalt decreased the agglomerative state of the system. The magnetic ferrites studied showed different characteristics according to the amount of dopant used, ranging from a very soft magnetic material (easy magnetization and demagnetization ) - for the system without cobalt - a magnetic material with a little stiffer behavior - for systems containing cobalt. The values of the coercive field increased with the increasing growth of cobalt, and the values of saturation magnetization and remanence increased up to x = 0,25 and then reduced. The different magnetic characteristics presented by the systems according to the amount of dopant used, allows the use of these materials as intermediates magnetic