Influência da adição de cinza do bagaço de cana calcinada em sistemas de pastas para cimentação de poços petrolíferos

Cementing operation is one of the most important stages in the oil well drilling processes and has main function to form hydraulic seal between the various permeable zones traversed by the well. However, several problems may occur with the cement sheath, either during primary cementing or during the well production period. Cements low resistance can cause fissures in the cement sheath and compromise the mechanical integrity of the annular, resulting in contamination of groundwater and producing zones. Several researches show that biomass ash, in particular, those generated by the sugarcane industry have pozzolanic activity and can be added in the composition of the cementing slurries in diverse applications, providing improvements in mechanical properties, revenue and cement durability. Due to the importance of a low cost additive that increases the mechanical properties in a well cementing operations, this study aimed to potentiate the use of sugarcane bagasse ash as pozzolanic material, evaluate the mechanisms of action of this one on cement pastes properties and apply this material in systems slurries aimed to cementing a well with 800 m depth and geothermal gradient of 1.7 °F/100 ft, as much primary cementing operations as squeeze. To do this, the ash beneficiation methods were realized through the processes of grinding, sifting and reburning (calcination) and then characterization by X-ray fluorescence, XRD, TG / DTG, specific surface area, particle size distribution by laser diffraction and mass specific. Moreover, the ash pozzolanic activity added to the cement at concentrations of 0%, 20% and 40% BWOC was evaluated by pozzolanic activity index with lime and with Portland cement. The evaluation of the pozzolanic activity by XRD, TG / DTG and compressive strength confirmed the ash reactivity and indicated that the addition of 20% in the composition of cement slurries produces improvement 34% in the mechanical properties of the slurry cured. Cement slurries properties evaluated by rheological measurements, fluid loss, free fluid, slurry sedimentation, thickening time and sonic strength (UCA) were satisfactory and showed the viability of using the sugarcane ash in cement slurries composition for well cementing

Efetividade do uso tópico de fluoreto e da escovação no controle de cáries produzidas "in vivo"

The objective of this clinical study was to evaluate the effectiveness of the toothbrushing with and without fluoride and the daily fluoride rinse (NaF 0.05%) on produced white spot, in vivo. This was a clinical study, controlled, randomized and triple blind. Thirty patients were selected for orthodontics reasons from Orthodontics Specialization Course at the Brazilian Dental Association - Section of Rio Grande do Norte. In this study it was used 4 bicuspid upper and lower. They had orthodontic reason for extractions, in 35 days, at least. The sample had one hundred and twenty teeth that received orthodontic bands. The bands were fixed with polycarboxylate cement, and there was a space standardized between bands and one surface of teeth. The four bicuspid of each patients were randomized and nominated as A, B, C and D. These nominations determinated the sequence of the extractions and what was done in each tooth. All the patients had been submitted to the toothbrushing with or without fluoride for 35 days. After this period, the A tooth of each patient was extracted to serve as control. The others teeth (B, C and D) were extracted one by each week. The entire sample was analyzed through the clinical examination and by laser fluorescence (DIAGNOdent®) in three different times: before orthodontic bands, 28 days after fixed and then removed the bands and, the last one, 07 days after one of the three treatments (toothbrushing with or without fluoride, tooth paste with fluoride and mouth rinse with fluoride). At the beginning all groups (A, B, C and D) had the same conditions, no significant difference was found. The same situation was found in a clinical examination. The results of the DIAGNOdent® for the groups that used tooth paste without fluoride, with fluoride and mouth rinse with fluoride, after 28 days, there was no significant difference. Clinically, the white spot was formed in all teeth after 28 days. When it was compared the three treated groups, the group without fluoride in tooth paste had worst result than the others groups. But there was no significant association between the number of active and inactive white spots and the type of treatment that the teeth had received. The demineralization of the enamel surface, under the orthodontic bands, it happened in a few weeks. The exposition of the white spots in oral environmental resulted in an improvement, but it was not enough to return to the values from the base line, either for the toothbrushing and/or the use of fluorite mouth rinse. Mouth rinse and toothpaste with fluoride have showed to reduce the incidence of demineralization in the enamel, but none seems to be superior to another one in an in vivo study

Estudo epidemiológico das parasitoses oculares na população de escolares da cidade de Natal-RN, Brasil

The objective of this study is to estimate the prevalence of Ocular Toxocariasis, Diffuse Unilateral Subacute Neuroretinitis (DUSN), Toxoplasma gondii infection and Ocular Toxoplasmosis in a student population in Natal-RN/Brazil and relate it to demographic, epidemiologic and socio-economic risk factors. The incidence of DUSN was observed in patients at the Federal University of Rio Grande do Norte Ophthalmology Service and the Prontoclinica de Olhos Ophthalmology clinic in Natal. In cases where a worm was found in the subretinal space, the result of treatment with photocoagulation using Green Laser (Eye Light ALCON) was evaluated in relation to final visual result. The sample was randomly selected among the schools of the four districts of Natal, according to the type of institution (public or private), its level (elementary or secondary), and study period (morning, afternoon or evening). The school population was studied from March to May, 2001. Initially, the students answered a questionnaire to evaluate demographic, epidemiologic and socio-economic risk factors. Afterwards, the following procedures were carried out: blood samples were taken for Toxoplasmosis (IgG, IgM) serology, hemogram, ophthalmological examination, consisting of clinical history, measurement of visual acuity, refraction under cycloplegia, biomicroscopy of the anterior segment and annexa, funduscopy and examination of extrinsic motility. The prevalence of Toxocariasis was 0.2% or 2 per one thousand students. The sample was insufficient to estimate the prevalence of DUSN. Seventy patients with DUSN diagnosis were examined from January, 2001 to January, 2003. A live worm was found in the subretinal space of all four patients in the acute phase, and these were treated with laser photocoagulation. After follow-up (average = 11.5 months), visual acuity improved in three eyes and remained unaltered in one eye. Worms were found in 22 of the 66 patients in the chronic phase, and these also were treated with laser photocoagulation. After a follow-up period of 13.1 months, on average, visual acuity improved in two of the patients, remained unchanged in 19 and worsened in one. The comparison of visual result before and after treatment was not statistically significant (p = 0.302). The diagnosis of DUSN in the acute phase, followed by prompt localization and destruction of the worm by photocoagulation, can improve the patient s vision. However, destruction of the worm by laser photocoagulation in eyes with DUSN in the chronic phase does not improve visual acuity. Seroprevalence for IgG was 46% (Confidence Interval CI 95%-42.9-49.2%) and for IgM it was 1.4% (CI 95% = 0.8-2.4%). The prevalence of ocular lesion was 1.15% (CI 95% = 0.6 - 2.0%). Socio-economic conditions were determinants in the prevalence of Systemic and Ocular Toxoplasmosis in the bivaried analysis and confirmed in the multivaried analysis (mother s scholarity illiterate/ OR = 2.9 and p < 0.001). The T. gondii infection prevalence, although high, was less than that found in studies performed in the South and Southeast of Brazil and that of Ocular Toxoplasmosis was completely discrepant, varying from 5 to 17 times less. Although important epidemiological variables such as owning a cat, drinking unfiltered water, and coming into contact with rivers or lakes showed an association in the preliminary analysis, they lost their influence when included in the logistic model. Future studies are scheduled to begin in March, 2004, in collaboration with other Brazilian and American universities in an attempt to discover the reason for these findings, as well as identifying the different strains of Toxoplasma gondii, and studying the sources of water utilized by the population of Natal Brazil

Desenvolvimento e análise de material compósito a base de penas de frango (fibras de queratina-KF) e matriz de poliéster insaturado

Use of natural fibres as a reinforcement material in the manufacture of composites show a series of advantages: availability, biodegradability, low weight and regeneration in relation to synthetic fibres, thus justifying its utilization. In the present research work, composites were developed with chicken feathers (KF), using unsaturated polyester resin as matrix, for diversified applications, mainly in the furniture/timber industry.At present, in Brazil the chicken feathers are used as part of the animal feed, even though this material possesses low aggregated value. The chicken feathers are hollow, light and resistant. After washing with water at room temperature, a part of the chicken feathers were treated with 2% NaOH. Composites were manufactured using treated and untreated chicken feathers with unsaturated orthothalic polyester resin and 1% peroxide as catalyser, obtained in the commerce. Samples with size 150x25x3 mm for mechanical tests were cut by laser in the composite plate. Mechanical analyses were carried out in the Laboratório de Metais e Ensaios Mecânicos UFRN. All the analyses were in accordance with ASTM standards. SEM analyses were also carried out on the samples.In the analyses of the results obtained, it was observed that the composites made with untreated chicken feathers showed better results (Traction 11.406 MPa and 9.107 MPa Bending 34.947 and 20.918 MPa for samples with and without treatment respectively) compared to the composite with treated feathers. Very low values of the water absorption results, evidenced the impermeability characteristic of the feathers. From the SEM images, the structure, fracture and the fibre/matrix adsorption can be evidenced. In the flammability test, it was observed that despite the feathers having sulfur as a constituent, natural inhibitor of flame, no burning support of the composites, because the manufacturing process of the composite

Análise da indução de fluxo de ar por convecção livre em chaminé solar

Experiments were performed to study the effect of surface properties of a vertical channel heated by a source of thermal radiation to induce air flow through convection. Two channels (solar chimney prototype) were built with glass plates, forming a structure of truncated pyramidal geometry. We considered two surface finishes: transparent and opaque. Each stack was mounted on a base of thermal energy absorber with a central opening for passage of air, and subjected to heating by a radiant source comprises a bank of incandescent bulbs and were performed field tests. Thermocouples were fixed on the bases and on the walls of chimneys and then connected to a data acquisition system in computer. The air flow within the chimney, the speed and temperature were measured using a hot wire anemometer. Five experiments were performed for each stack in which convective flows were recorded with values ranging from 17 m³ / h and 22 m³ / h and air flow velocities ranging from 0.38 m / s and 0.56 m / s for the laboratory tests and air velocities between 0.6 m/s and 1.1m/s and convective airflows between 650 m³/h and 1150 m³/h for the field tests. The test data were compared to those obtained by semi-empirical equations, which are valid for air flow induced into channels and simulated data from 1st Thermodynamics equation. It was found that the chimney with transparent walls induced more intense convective flows than the chimney with matte finish. Based on the results obtained can be proposed for the implementation of prototype to exhaust fumes, mists, gases, vapors, mists and dusts in industrial environments, to help promote ventilation and air renewal in built environments and for drying materials, fruits and seeds

Desenvolvimento de um secador spray para obtenção de pós finos de precursores de nióbio

This work presents a spray-dryer designed to oxalate-niobate precursors and suitable for the production of Niobium Carbide. The dryer was intended to produce powders of controlled particle size. First, the precursor is dissolved in water to produce a solution of known concentration and then it is atomized on the spray-dryer to produce the powder. This equipment consists of a 304 stainless steel chamber, 0.48 m x 1.9 m (diameter x length), with a conical shape at the lower portion, which is assembled on a vertical platform. The chamber is heated by three 4 kW electrical resistances. In this process, drying air is heated as it flows inside a serpentine surrounding the chamber, in contrary to more traditional processes in which the hot drying air is used to heat the component. The air enters the chamber at the same temperature of the chamber, thus avoiding adherence of particles on the internal surface. The low speed flow is concurrent, directed from the top to the bottom portion of the chamber. Powders are deposited on a 0.4 m diameter tray, which separates the cylindrical portion from the conical portion of the chamber. The humid air is discharged though a plug placed underneath the collecting tray. A factorial experimental planning was prepared to study the influence of five parameters (concentration, input flow, operation temperature, drying air flow and spray air flow) on the characteristics of the powders produced. Particle size distribution and shape were measured by laser granulometry and scanning electronic microscopy. Then, the powders are submitted to reaction in a CH4 / H2 atmosphere to compare the characteristics of spray-dried powders with powders synthetizided by conventional methods

Efeitos da terapia fotodinâmica com aluminio – cloro ftalocianina sobre a peroxidação lipídica e produtos antioxidantes em tecidos inflamados animais

Photodynamic therapy (PDT) consists of a non-toxic photosensitizing agent (FS) administration followed by a laser source resulting in a sequence of photochemical and photobiological processes that generate reactive oxygen species (ROS) that damaging cells. The present work evaluated the effects of PDT nanoemulsion-aluminum chloride phthalocyanine (AlClFc) mediated on malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels, which represent indicators involved in oxidative stress and antioxidant defenses. For this purpose, this study used 120 female rats of the Rattus norvegicus species, Wistar race, divided into 5 groups: Healthy (H), with periodontal disease (PD), with periodontal disease and treatment with FS (F), with periodontal disease and treatment with the laser (L); and periodontal disease and treatment with PDT (FL). An experimental model for represent periodontal disease (PD) was induced by ligature (split-mouth). Seven days later the induction of PD, the treatments were instituted according to the groups. In the group treated with PDT was applied 40μl FS (5μM) followed by laser irradiation diode InGaAlP (660nm, 100J / cm2). The rats were sacrificed on the 7th and 28th day after treatment and tissue specimens were removed and subjected to histological, immunohistochemical methods and enzymatic colorimetric measurements with detection by UV / VIS spectroscopy. Inflammatory changes, connective tissue disorganization and alveolar bone loss were displaying in groups with PD induced. The enzyme dosages showed that MDA levels were higher in PD induced groups, with no statistically significant differences (p> 0.05). High levels of GSH were found in groups L (p = 0.028) and FL (p = 0.028) compared with PD group, with statistically significant differences. Immunohistochemistry for SOD showed higher immunostaining in L and FL groups, compared to the PD group without statistically significant differences (p> 0.05). GPx showed lower immunoreactivity in the DP group when compared to the other groups and statistically significant differences were observed between the DPxL groups (p <0.05). TFD administered in this experiment did not induce elevation of MDA levels significantly increased the GSH levels and showed intense immunostaining pada SOD and GPx, showing that this therapy does not accentuated lipid peroxidation, however, it was able to induce effects on the antioxidant defenses processes. The LBI therapy appeared to show photomodulatory promoting effects reduction of the MDA levels, increasing GSH levels and with intense immunostaining for SOD and GPx, demonstrating that laser therapy induced antioxidant effects.

Obtenção e caracterização de dióxido de estanho nanoestruturado pelo método de síntese contínua por combustão em solução

Continuous Synthesis by Solution Combustion was employed in this work aiming to obtain tin dioxide nanostructured. Basically, a precursor solution is prepared and then be atomized and sprayed into the flame, where its combustion occurs, leading to the formation of particles. This is a recent technique that shows an enormous potential in oxides deposition, mainly by the low cost of equipment and precursors employed. The tin dioxide (SnO2) nanostructured has been widely used in various applications, especially as gas sensors and varistors. In the case of sensors based on semiconducting ceramics, where surface reactions are responsible for the detection of gases, the importance of surface area and particle size is even greater. The preference for a nanostructured material is based on its significant increase in surface area compared to conventional microcrystalline powders and small particle size, which may benefit certain properties such as high electrical conductivity, high thermal stability, mechanical and chemical. In this work, were employed as precursor solution tin chloride dehydrate diluted in anhydrous ethyl alcohol. Were utilized molar ratio chloride/solvent of 0,75 with the purpose of investigate its influence in the microstructure of produced powder. The solution precursor flux was 3 mL/min. Analysis with X-ray diffraction appointed that a solution precursor with molar ratio chloride/solvent of 0,75 leads to crystalline powder with single phase and all peaks are attributed to phase SnO2. Parameters as distance from the flame with atomizer distance from the capture system with the pilot, molar ratio and solution flux doesn t affect the presence of tin dioxide in the produced powder. In the characterization of the obtained powder techniques were used as thermogravimetric (TGA) and thermodiferential analysis (DTA), particle size by laser diffraction (GDL), crystallographic analysis by X-ray diffraction (XRD), morphology by scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and electrical conductivity analysis. The techniques used revealed that the SnO2 exhibits behavior of a semiconductor material, and a potentially promising material for application as varistor and sensor systems for gas

Revestimentos a base de Ta/Al2O3 produzidos por aspersão térmica sobre substrato metálico

Metal substrates were coated by thermal spraying plasma torch, they were positioned at a distance of 4 and 5 cm from the nozzle exit of the plasma jet. The starting materials were used for deposition of tantalum oxide powder and aluminium. These two materials were mixed and ground into high-energy mill, then immersed in the torch for the production of alumina coating infused with particles of tantalum with nano and micrometric size. The spraying equipment used is a plasma torch arc not transferred, which operating in the range of 250 A and 80 V, was able to produce enough heat to ignite aluminothermic between Ta2O5 and aluminum. Upon reaching the plasma jet, the mixing powders react with the heat of the blaze, which provides sufficient energy for melting aluminum particles. This energy is transferred through mechanisms of self-propagating to the oxide, beginning a reduction reaction, which then hits on the surface of the substrate and forms a coating on which a composite is formed by a junction metal - ceramic (Ta +Al2O3). The phases and quantification of each were obtained respectively by X-ray diffraction and the Rietveld method. Morphology by scanning electron microscopy and chemical analysis by energy dispersive spectroscopy EDS. It was also performed measurements of the substrate roughness, Vickers microhardness measurements in sprays and determination of the electron temperature of the plasma jet by optical emission spectroscopy EEO. The results confirmed the expectation generated around the end product of spraying the mixture Ta2O5 + Al, both in the formation of nano-sized particles and in their final form. The electron excitation temperature was consistent with the purpose of work, in addition, the thermodynamic temperature was efficient for the reduction process of Ta2O5. The electron excitation temperature showed values of 3000, 4500 and 8000 K for flows10, 20 and 30 l / min respectively, these values were taken at the nozzle exit of the plasma jet. The thermodynamic temperature around 1200 ° C, was effective in the reduction process of Ta2O5

Influência da adição de cinza do bagaço de cana calcinada em sistemas de pastas para cimentação de poços petrolíferos

Cementing operation is one of the most important stages in the oil well drilling processes and has main function to form hydraulic seal between the various permeable zones traversed by the well. However, several problems may occur with the cement sheath, either during primary cementing or during the well production period. Cements low resistance can cause fissures in the cement sheath and compromise the mechanical integrity of the annular, resulting in contamination of groundwater and producing zones. Several researches show that biomass ash, in particular, those generated by the sugarcane industry have pozzolanic activity and can be added in the composition of the cementing slurries in diverse applications, providing improvements in mechanical properties, revenue and cement durability. Due to the importance of a low cost additive that increases the mechanical properties in a well cementing operations, this study aimed to potentiate the use of sugarcane bagasse ash as pozzolanic material, evaluate the mechanisms of action of this one on cement pastes properties and apply this material in systems slurries aimed to cementing a well with 800 m depth and geothermal gradient of 1.7 °F/100 ft, as much primary cementing operations as squeeze. To do this, the ash beneficiation methods were realized through the processes of grinding, sifting and reburning (calcination) and then characterization by X-ray fluorescence, XRD, TG / DTG, specific surface area, particle size distribution by laser diffraction and mass specific. Moreover, the ash pozzolanic activity added to the cement at concentrations of 0%, 20% and 40% BWOC was evaluated by pozzolanic activity index with lime and with Portland cement. The evaluation of the pozzolanic activity by XRD, TG / DTG and compressive strength confirmed the ash reactivity and indicated that the addition of 20% in the composition of cement slurries produces improvement 34% in the mechanical properties of the slurry cured. Cement slurries properties evaluated by rheological measurements, fluid loss, free fluid, slurry sedimentation, thickening time and sonic strength (UCA) were satisfactory and showed the viability of using the sugarcane ash in cement slurries composition for well cementing