Avaliação da molhabilidade de soluções de tensoativos em aço inoxidável

With the increasing industrialization of the planet caused by globalization, it has become increasingly common to search for highly resistant and durable materials for many diverse branches of activities. Thus, production and demand for materials that meet these requirements have constantly increased with time. In view of this, stainless steel is presented as one of the materials which are suitable applications, due to many features that are interesting for several segments of the industry. Concerns of oil companies over heavy oil reservoirs have grown steadily for the last decades. Rheological properties of these oils impair their transport in conventional flow systems. This problem has created the need to develop technologies to improve flow and transport, reducing operation costs so as to enable oil production in the reservoir. Therefore, surfactant-based chemical systems are proposed to optimize transport conditions, effected by reduction of interfacial tensions, thereby enhancing the flow of oil in ducts and reducing load losses by friction. In order to examine such interactions, a study on the wettability of metallic surfaces has been undertaken, represented by measuring of contact angle of surfactant solutions onto flat plates of 304 stainless steel. Aqueous solutions of KCl, surfactants and mixtures of surfactants, with linear and aromatic hydrocarbon chain and ethoxylation degrees ranging between 20 to 100, have been tested. The wettability was assessed by means of a DSA 100 krüss goniometer. The influence of roughness on the wettability was also investigated by machining and polished the stainless steel plates with sandpapers of references ranging between 100 of 1200. The results showed that sanding and polishing plates result in decrease of wettability. As for the solutions, they have provided better wettability of the stainless steel than the KCl solutions tested. It was also been concluded that surfactant mixtures is an option to be considered, since they promote interactions that generate satisfactory contact angles for a good wettability on the stainless steel plate. Another conclusion refers to the influence of the ethoxylation degree of the nonionic surfactant molecules on wettability. It has been observed that contact angles decrease with decreasing ethoxylation degrees. This leads us to conclude that molecules with higher ethoxylation degree, being more hydrophobic, decrease the interaction of water with the ducts, thereby reducing friction and improving the flow

Aplicação de microemulsão na recuperação de petróleo de reservatórios carbonáticos

The large investment in exploration activities offshore Brazil has generated new findings, generally in carbonate reservoirs, with different wettability conditions usually considered in the sandstone, strongly water-wet. In general, the carbonates reservoirs tend to be oil-wet, it difficult to mobilize of oil these reservoirs. These oils can be mobilized by different methods, or it may reverse the wettability of the surface of the reservoir and facilitate the flow of oil, improving production rates. Thus, the objective of this work was to study the influence of inversion on the wettability of the rock in the production and recovery of petroleum from carbonate reservoirs, using microemulsions. Three systems were chosen with different classes of surfactants: a cationic (C16TAB), an anionic (SDS) and nonionic (Unitol L90). Studies of the influence of salinity on the formation of the microemulsion as well as the characterization of fluids using density and viscosity measurements were also performed. To verify the potential of microemulsion systems in changing the wettability state of the chalk oil-wet to water-wet, contact angle measurements were performed using chalk of neutral-wet as surface material. Overall, with respect to the ionic character of the surfactants tested, the cationic surfactant (C16TAB) had a greater potential for reversal in wettability able to transform the rock wettability neutral to strongly water-wet, when compared with the anionic surfactant (SDS) and nonionic (Unitol L90), which showed similar behavior, improving the wettability of the rock to water. The microemulsions of all surfactants studied were effective in oil recovery, resulting in 76.92% for the system with C16TAB, 67.42% for the SDS and 66.30% for Unitol L90 of residual oil

Efeitos da inclinação da esteira na marcha de indivíduos hemiparéticos crônicos

Objective: To examine the effects of treadmill inclinations on the walking of hemiparetic chronic subjects. Design: Observational descriptive study. Location: Laboratory of human movement analysis. Participants: Eighteen subjects, 10 men and 8 women were evaluated, with a mean age of 55.3 ± 9.3 years and the time since the injury of about 36 ± 22.8 months. Intervention: Not applicable. Main Outcome Measures: All subjects were evaluated for functional independence (Functional Independence Measure - FIM) and balance (Berg Balance Scale). Angular variations of the hips, knees and ankles in the sagittal plane were observed, as well as the speed of the movement (m/s), cadence (steps/min), stride length (m), cycle time (s), step time on the paretic leg and on the non-paretic leg (s), support phase time and balance phase time on the paretic leg (s) and the ratio of symmetry inter-limb as subjects walked on a treadmill at three conditions of inclination (0%, 5% and 10% ). Results: There were angular increases in the initial contact of the hip, knee and ankle, amplitude increase in the hip between 0% and 10% (37.83 ± 5.23 versus 41.12 ± 5.63, p < 0,001) and 5% and 10% (38.80 ± 5.96 versus 41.12 ± 5.63, p = 0,002), amplitude increases in the knee between 0% and 10% (47.51 ± 15.07 versus 50, 30 ± 12.82, p = 0,040), extension decreases in the hip, dorsiflexion increases in the balance phase and in the time of support phase from 0% to 5% (0.83 ± 0.21 versus 0.87 ± 0, 20, p = 0,011) and 0% and 10% (0.83 ± 0.21 versus 0.88 ± 0.23, p = 0,021). Conclusion: The treadmill inclination promoted angle changes as such as the increase of the angle of the hip, knee and ankle during the initial contact and the balance phase and the increase of the range of motion of the hip and knee; furthermore, it also promoted the increase of the support time of the paretic lower limb

Efeitos do treino em esteira na marcha com dupla tarefa de indivíduos com doença de Parkinson: ensaio clínico controlado randomizado

Background: The gait automaticity loss difficults realization of concurrent activities - Dual Task (DT). In these situations, individuals with Parkinson`s disease (PD) show a significant reduction in gait velocity and stride length, as strides variability and asymmetry increased, factors predisposing to falls. However, recent studies have shown that training involving DT may cause subsequent improvements in gait variables with DT in individuals with PD. The treadmill use was adopted by this study, by promoting greater regularity in step and enhance training. Objective:To investigate immediate effects of gait training associated with cognitive tasks on gait in individuals with PD. Methods: Twenty-two volunteers were randomly divided into two groups: control group (n = 11), who performed gait training on a treadmill for 20 minutes, and the experimental group (n = 11), who performed treadmill gait training for 20 minutes associated with cognitive tasks of verbal fluency, memory, and spatial planning. Participants were evaluated in phase on of antiparkinsonian medication as the demographic, clinical and anthropometric (identification form), cognitive status (Montreal Cognitive Assessment - MoCA), executive function (Frontal Assessment Battery), level of physical disability (Hoehn and Yahr Modified), motor and functional status (Unified Rating Scale for Parkinson`s Disease - UPDRS), and kinematics (Qualisys Motion Capture System). Results: There were not differences between groups, but both showed improvement after the intervention. The control group had an increase in velocity (p = 0.008), stride length (p = 0.04), step length (p = 0.02) and decreased double support time(p = 0.03). The experimental group showed an increase in speed (p = 0.002), stride length (p = 0.008), step length (p = 0.02) and cadence (p = 0.01), as well as a decrease in the width stride (p = 0.001) and total support time (p = 0.02). As the angular variables, the experimental group had a significant increase in the initial contact angle of ankle (p = 0.01). Conclusion: The gait training combined with cognitive activities didn`t provide significant improvements in gait variables with DT, but this study was the first to demonstrate that gait training on treadmill as simple task minimized the negative interference of DT in PD

Síntese enzimática de biosurfactante e sua aplicabilidade na indústria do petróleo

Enzymes have been widely used in biosynthesis/transformation of organic compounds in substitution the classic synthetic methods. This work is the first writing in literature of enzymatic synthesis for attainment the biossurfactants, the use glucose sucrose, ricinoleic acid e castor oil as substratum, and as biocatalyst, used immobilized lipase Thermomyces lanuginose, Rhizomucor miehei and the Candida antarctica lipase B; alkaline protease and neutral protease from Bacillus subtillis and yeast Saccharomyces cerevisiaeI. The analysis of HPLC (high performance liquid chromatography) showed that highest conversions were reached of used the alkaline protease from Bacillus subtillis. Laboratory tests, to evaluate the applicability, indicated that the produced biosurfactantes had good stability in presence of salts (NaCl) and temperature (55 e 25°C), they are effective in the reduction of the superficial tension and contac angle, but they have little foaming capacity, when compared with traditional detergents. These results suggest that the prepared surfactants have potential application as wetting agent and perforation fluid stabilizer

Uso da palha de carnaúba em revestimento de dutos

In this work, the plant species Copernicia prunifera (Miller) H. E. Moore (carnauba), naturally occurring which prevails in the northeast region of Brazil was the subject of studies aiming its use as external coating of pipelines used in petroleum industry. The part of the plant worked were the leaves, also called straw, which were coated with resinous material. For this purpose, it was necessary to evaluate the effectiveness of the use of acrylic resins in the straw carnauba coating. The properties of the untreated carnauba straw and chemically treated with sodium hydroxide, hexane and carbon tetrachloride were investigated by ATRFTIR, SEM and thermal analysis. The first two techniques showed that treatment with solvents has caused major changes in the straw surface, while the thermal analysis indicated that the sodium hydroxide caused variations in thermal stability of straw constituents. Water absorption measurements showed that treatments have accelerated the absorption process and the reduction of contact angle values for treated samples with solvents indicated higher hidrophilicity of straw. The tensile tests showed lower values of elastic modulus and tensile strength for treated samples. Furthermore, coatings using pure commercial resins A and B as well as the formulations with clay were applied in straw and they were examined once again through thermal analysis, water absorption measurements, contact angle and mechanical tests. To analyze the effect of heat ageing, samples were subjected to tensile tests again in order to assess its resistance. The results showed that the resins/clay formulations increased thermal stability of straw, they promoted a good impermeabilization and caused significant decrease in the values of elastic modulus and tensile strength. Evaluating the ageing effect on the mechanical properties, it has been showed good recovery to the coated straw with the formulations A 60 and A 80% in modulus and tensile strength values and elongation at break values have remained very close. It is thus concluded that the carnauba straw can be used as a coating of pipelines with significant cost savings, since there is no need for pretreatment for its use and shows itself as a viable biotechnology alternative, contributing to the quality of coatings material and environment preservation.

Aplicação de sabões de ácidos graxos epoxidados como inibidores de corrosão em oleoduto

Corrosion usually occurs in pipelines, so that it is necessary to develop new surface treatments to control it. Surfactants have played an outstanding role in this field due to its capacity of adsorbing on metal surfaces, resulting in interfaces with structures that protect the metal at low surfactant concentrations. The appearance of new surfactants is a contribution to the area, as they increase the possibility of corrosion control at specific conditions that a particular oil field presents. The aim of this work is to synthesize the surfactants sodium 12 hydroxyocadecenoate (SAR), sodium 9,10-epoxy-12 hydroxyocadecanoate (SEAR), and sodium 9,10:12,13-diepoxy-octadecanoate (SEAL) and apply them as corrosion inhibitors, studying their action in environments with different salinities and at different temperatures. The conditions used in this work were chosen in order to reproduce oil field reality. The study of the micellization of these surfactants in the liquid-gas interface was carried out using surface tensiometry. It was observed that cmc increased as salt concentration was increased, and temperature and pH were decreased, while cmc decreased with the addition of two epoxy groups in the molecule. Using the values of cmc and the Gibbs equation, the values of Gibbs free energy of adsorption, area per adsorbed molecule, and surface excess were calculated. The surface excess increases as salt concentration and temperature decreases, increasing as pH is increased. The area per adsorbed molecule and the free energy of adsorption decrease with salt concentration, temperature, and pH increase. SAXS results showed that the addition of epoxy group in surfactant structure results in a decrease in the repulsion between the micelles, favoring the formation of more oblong micellar structures, ensuring a better efficiency of metal coverage. The increase in salt and surfactant concentrations provides an increase in micellar diameter. It was shown that the increase in temperature does not influence micellar structure, indicating thermal stability that is advantageous for use as corrosion inhibitor. The results of inhibition efficiency for the surfactants SEAR and SEAL were considered the best ones. Above cmc, adsorption occurred by the migration of micelles from the bulk of the solution to the metal surface, while at concentrations below cmc film formation must be due to the adsorption of semi-micellar and monomeric structures, certainly due to the presence of the epoxy group, which allows side interactions of the molecule with the metal surface. The metal resistance to corrosion presented values of 90% of efficiency. The application of Langmuir and Frumkin isotherms showed that the later gives a better description of adsorption because the model takes into account side interactions from the adsorbing molecules. Wettability results showed that micelle formation on the solid surface occurs at concentrations in the magnitude of 10-3 M, which isthe value found in the cmc study. This value also justifies the maximum efficiencies obtained for the measurements of corrosion resistance at this concentration. The values of contact angle as a function of time suggest that adsorption increases with time, due to the formation of micellar structures on metal surface

Efeito da desinfecção por aerossóis sobre a capacidade de umedecimento de moldes de poliéter por gesso tipo IV

A desinfecção de todo e qualquer molde obtido é medida de biossegurança obrigatória na atividade clínica. Tão importante quanto a desinfecção é a seleção do método e da solução desinfetante a ser utilizada para cada material de moldagem. É imperativo que a capacidade de reprodução de detalhes, a estabilidade dimensional e o grau de umedecimento (ou molhabilidade) não sejam criticamente afetados. O propósito deste trabalho foi avaliar o grau de umedecimento de uma marca comercial de poliéter (Impregum F) por três diferentes marcas comerciais de gesso tipo IV (Herostone, Durone e Polirock), após sua desinfecção por aerossóis de hipoclorito de sódio 1% (líquido de Milton) ou glutaraldeído 2% (Glutalabor II). Foram confeccionados 45 moldes de poliéter, os quais, em grupos de 15, receberam aerossóis de água (Grupo Controle), Líquido de Milton ou Glutalabor II. em seguida, sobre a superfície dos moldes foram confeccionados modelos de gesso tipo IV, em número de 5 para cada marca de gesso. Após seu seccionamento mediano e preparo da superfície de corte, os modelos foram levados ao microscópio Carl Zeiss para leitura do ângulo de contato. Os resultados obtidos permitiram concluir que: a) a capacidade de umedecimento do poliéter por diferentes marcas comerciais de gesso tipo IV variou para os gessos estudados; b) o gesso Durone adaptou-se melhor aos moldes de poliéter do que os gessos Herostone e Polirock; c) a desinfecção dos moldes com aerossóis de hipoclorito de sódio 1% (líquido de Milton) ou glutaraldeído 2% (Glutalabor) não afetou a adaptação entre os gessos e o poliéter.

Biodegradação de filmes de PP/PCL em solo e solo com chorume

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicação do eletrocapilaridade na manipulação de microgotas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alteração das propriedades superficiais do alumínio via eletrólise e plasma

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Avaliação de implantes dentários da liga experimental Ti-30Ta após tratamento de superfície biomimético e imobilização com bisfosfonato

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo de polímeros comerciais tratados a plasma em pressão atmosférica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização topográfica e estrutural de filmes poliméricos provenientes de acetileno (C2H2) depositados a plasma sobre substratos lisos e rugosos

Pós-graduação em Física - FEG

Tratamento de polímeros com jato de plasma em pressão atmosférica

Pós-graduação em Física - FEG