Formulação e caracterização de pastas espumadas por incorporação de ar e estabilizantes minerais

Cementing operations may occur at various stages of the life cycle of an oil well since its construction until its definitive abandonment. There are some situations in which the interest zones are depleted or have low fracture pressure. In such cases, the adoption of lowdensity cement slurries is an efficient solution. To this end, there are basically three ways to reduce the density of cement slurries: using microspheres, water extending additives or foamed cement. The objective of this study is to formulate, to study and to characterize lowdensity foamed cement, using an air entrainment surfactant with vermiculite or diatomite as water extenders and stabilizers. The methodology consists on preparation and evaluation of the slurries under the American Petroleum Institute (API) and the Brazilian Association of Technical Standards (ABNT) guidelines. Based on calculated densities between 13 and 15 ppg (1.559 and 1.799 g/cm3), the slurries were prepared with fixed surfactant concentration, varying the concentrations of vermiculite and diatomite and were compared with the base slurries. The results of plastic viscosity, yield point and gel strength and the compressive strength for 24 h showed that the slurries presented suitable rheology and mechanical strength for cementing operations in oil wells, and had their densities reduced between 8.40 and 11.89 ppg (1.007 and 1.426 g/cm3). The conclusion is that is possible, under atmospheric conditions, to obtain light weighted foamed cement slurries with satisfactory rheological and mechanical properties by means of air entrainment and mineral additions with extenders and stabilizers effects. The slurries have great potential for cementing operations; applicability in deep wells, in low fracture gradient formations and in depleted zones and bring cost savings by reducing the cementing consumption

Estabilizador de sistema de potência para máquinas síncronas de polos salientes utilizando a transformada Wavelet

The power system stabilizers are used to suppress low-frequency electromechanical oscillations and improve the synchronous generator stability limits. This master thesis proposes a wavelet-based power system stabilizer, composed of a new methodology for extraction and compensation of electromechanical oscillations in electrical power systems based on the scaling coefficient energy of the maximal overlap discrete wavelet transform in order to reduce the effects of delay and attenuation of conventional power system stabilizers. Moreover, the wavelet coefficient energy is used for electric oscillation detection and triggering the power system stabilizer only in fault situations. The performance of the proposed power system stabilizer was assessed with experimental results and comparison with the conventional power system stabilizer. Furthermore, the effects of the mother wavelet were also evaluated in this work

Padronização de testes para avaliação do estado de mania e potencial anti-maníaco de um agonista do receptor NOP

Bipolar disorder is characterized by mood impairment, alternating between mania/hypomania and depression, and its exact pathophysiology is already unknown. The treatment of bipolar disorder is based on prevention of the manic and depressive episodes using mood stabilizers. Nociceptin/orfanin FQ (N/OFQ) is an endogenous heptadecapeptide which binds as an agonist to NOP receptor, which is a G-coupled inhibitory receptor. N/OFQ and its receptor modulate a lot of functions in the organism, including emotional processes. It is known that the plasmatic concentration of N/OFQ is altered in patients in both phases depressive and manic of bipolar disorder and it is assumed that this system has a role on the etiology of this disorder. Concerning mania, the animal models used in research tend to focus in an unique aspect of the manic behavior, as hyperactivity or agressivity. In the 60’s, the hole board test was proposed, and it consists of an apparatus with holes where a behavior known as head-dippings is measured. High levels of head-dippings are suggestive of neophilia, while low levels can be characteristic of an anxious-like behavior. As the increase of exploratory and goal-directed behavior are characteristics of manic behavior, this test could help in mania research. Thus, this work was organized in 3 steps and aims to: (1) investigate the induction of a manic-like state promoted by ouabain, a Na+/K+-ATPase inhibitor, in the mouse open field test; (2) set up the hole board as a test to measure manic-like behaviors; and (3) investigate the N/OFQ effects in prevention of this kind of behavior on hole board. Male Swiss mice were used in this study, and they take part of only one of the described steps. Depending on the step performed, mice received one or more of the following treatments: (1) ouabain 10-6 , 10-5 , 10-4 , 10-3 or 10-2 M, intracerebroventricular (icv); (2) sodium valproate 300 mg/kg, intraperitoneal (ip); (3) sodium valproate 400 mg/kg, ip; (4) diazepam 1 mg/kg, ip; (5) methylphenidate 10 mg/kg, ip; and (6) N/OFQ 0,1 or 1 nmol, icv. The results suggest that hole board can be used to evaluate a manic state, through analysis of different animal behaviors. However, it was not possible to standard the model of Na+ /K+ -ATPase dysfunction through ouabain administration in mice. Moreover, the data suggest that N/OFQ, at the doses tested, has not affected the methylphenidate-induced mania-like behavior. Taken together, the results point to a new approach of manic research, through the hole board using. However, more studies are necessary in order to verify the role of N/OFQ system on bipolar disorder.

Formulação e caracterização de pastas espumadas por incorporação de ar e estabilizantes minerais

Cementing operations may occur at various stages of the life cycle of an oil well since its construction until its definitive abandonment. There are some situations in which the interest zones are depleted or have low fracture pressure. In such cases, the adoption of lowdensity cement slurries is an efficient solution. To this end, there are basically three ways to reduce the density of cement slurries: using microspheres, water extending additives or foamed cement. The objective of this study is to formulate, to study and to characterize lowdensity foamed cement, using an air entrainment surfactant with vermiculite or diatomite as water extenders and stabilizers. The methodology consists on preparation and evaluation of the slurries under the American Petroleum Institute (API) and the Brazilian Association of Technical Standards (ABNT) guidelines. Based on calculated densities between 13 and 15 ppg (1.559 and 1.799 g/cm3), the slurries were prepared with fixed surfactant concentration, varying the concentrations of vermiculite and diatomite and were compared with the base slurries. The results of plastic viscosity, yield point and gel strength and the compressive strength for 24 h showed that the slurries presented suitable rheology and mechanical strength for cementing operations in oil wells, and had their densities reduced between 8.40 and 11.89 ppg (1.007 and 1.426 g/cm3). The conclusion is that is possible, under atmospheric conditions, to obtain light weighted foamed cement slurries with satisfactory rheological and mechanical properties by means of air entrainment and mineral additions with extenders and stabilizers effects. The slurries have great potential for cementing operations; applicability in deep wells, in low fracture gradient formations and in depleted zones and bring cost savings by reducing the cementing consumption