Efeitos de acoplamentos biquadráticos e campos aleatórios em vidros de spins

In this work we have studied the effects of random biquadratic and random fields in spin-glass models using the replica method. The effect of a random biquadratic coupling was studied in two spin-1 spin-glass models: in one case the interactions occur between pairs of spins, whereas in the second one the interactions occur between p spins and the limit p > oo is considered. Both couplings (spin glass and biquadratic) have zero-mean Gaussian probability distributions. In the first model, the replica-symmetric assumption reveals that the system presents two pha¬ses, namely, paramagnetic and spin-glass, separated by a continuous transition line. The stability analysis of the replica-symmetric solution yields, besides the usual instability associated with the spin-glass ordering, a new phase due to the random biquadratic cou¬plings between the spins. For the case p oo, the replica-symmetric assumption yields again only two phases, namely, paramagnetic and quadrupolar. In both these phases the spin-glass parameter is zero. Besides, it is shown that they are stable under the Almeida-Thouless stability analysis. One of them presents negative entropy at low temperatures. We developed one step of replica simmetry breaking and noticed that a new phase, the biquadratic glass phase, emerge. In this way we have obtained the correct phase diagram, with.three first-order transition lines. These lines merges in a common triple point. The effects of random fields were studied in the Sherrington-Kirkpatrick model consi¬dered in the presence of an external random magnetic field following a trimodal distribu¬tion {P{hi) = p+S(hi - h0) +Po${hi) +pS(hi + h0))- It is shown that the border of the ferromagnetic phase may present, for conveniently chosen values of p0 and hQ, first-order phase transitions, as well as tricritical points at finite temperatures. It is verified that the first-order phase transitions are directly related to the dilution in the fields: the extensions of these transitions are reduced for increasing values of po- In fact, the threshold value pg, above which all phase transitions are continuous, is calculated analytically. The stability analysis of the replica-symmetric solution is performed and the regions of validity of such a solution are identified

Vidros de spins de Ashkin-Teller com interações entre p-spins

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Preparação de vidros e vitrocerâmicas de óxidos de metais pesados contendo prata: propriedades ópticas, estruturais e eletroquímicas

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

Logística reversa numa empresa de laminação de vidros: um estudo de caso

Este trabalho apresenta uma aplicação da Logística Reversa numa empresa multinacional que atua na área de laminação de vidros no Brasil. Na empresa estudada, a sucata gerada pelos seus clientes pode ser usada para realimentar o seu processo de produção. Inicialmente, são discutidos os principais aspectos relacionados ao tema, tais como, definição de Logística Reversa, ciclo de vida do produto, motivos e destinos do retorno, além dos fatores que influenciam a eficiência de um processo de Logística Reversa. A seguir, ilustradas pelo estudo de caso, são apresentadas e comentadas as etapas para uma implementação de um sistema de Logística Reversa ser bem sucedida. Finalmente, comentam-se as dificuldades, ganhos e vantagens competitivas obtidas por empresas que adotaram soluções da Logística Reversa, em particular na empresa em que o estudo de caso foi desenvolvido.

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

Estudo da modificação de bentonita para a remoção de fenol em águas produzidas na indústria de petróleo

This study evaluates the inclusion of quaternary ammonium salt, bromide hexadecyl trimethyl ammonium (HDTMA-Br) on sodium bentonite to evaluate their performance on the adsorption of phenol present in produced water. It was observed an increase in d001 samples modified with HDTMA-Br by diffraction of X-rays, showing the intercalation of quaternary ammonium cations in the interlamellar layers of clay. Through the adsorption isotherms could be abserver adsorption behavior of sodium bentonite and organophilic bentonite produced in three different concentrations of HDTMA-Br for adsorption of phenol, which is the main phenolic compound found in the product water. Different concentrations of synthetic solutions of phenol were placed in contact with these adsorbents under the same conditions of agitation and temperature. The adsorbent showed adsorptive favorable, especially the clay modified with the highest concentration of HDTMA-Br, 150% CEC of clay, BEN30-14, with higher amounts of phenol adsorbed per gram of adsorbent (mg.g-1)

Análise dos Processos de Flotação e Oxidação Avançada para o Tratamento de Efluente Modelo da Indústria do Petróleo

The generation of wastes in most industrial process is inevitable. In the petroleum industry, one of the greatest problems for the environment is the huge amount of produced water generated in the oil fields. This wastewater is a complex mixture and present great amounts. These effluents can be hazardous to the environmental without adequate treatment. This research is focused in the analysis of the efficiencies of the flotation and photo-oxidation processes to remove and decompose the organic compounds present in the produced water. A series of surfactants derivated from the laurilic alcohol was utilized in the flotation to promote the separation. The experiments have been performed with a synthetic wastewater, carefully prepared with xylene. The experimental data obtained using flotation presented a first order kinetic, identified by the quality of the linear data fitting. The best conditions were found at 0.029 g.L-1 for the surfactant EO 7, 0.05 g.L-1 for EO 8, 0.07 g.L-1 for EO 9, 0.045 g.L-1 for EO 10 and 0.08 g.L-1 for EO 23 with the following estimated kinetic constants: 0.1765, 0.1325, 0.1210, 0.1531 and 0.1699 min-1, respectively. For the series studied, the most suitablesurfactant was the EO 7 due to the lower reagent consumption, higher separation rate constant and higher removal efficiency of xylene in the aqueous phase (98%). Similarly to the flotation, the photo-Fenton process shows to be efficient for degradation of xylene and promoting the mineralization of the organic charge around 90% and 100% in 90 min

Propriedades estruturais e térmicas de vidros teluretos 20Li2O-80TeO2

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

Síntese e caracterização de poliacrilamidas modificadas para utilização na indústria do petróleo

Modified polyacrylamides with ≅ 0.2 mol % of N,N-dihexylacrylamide and hydrolysis degree from 0 to 25 % were synthesized by micellar copolymerization. The hydrophobic monomer was obtained by the reaction between acryloyl chloride and N,Ndihexylamine and characterized by infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The polymer molecular structures were determined through 1H and 13C NMR spectroscopy and the polymers were studied in dilute and semi-dilute regimes by viscometry, rheometry, static light scattering and photon correlation spectroscopy, at the temperature range from 25 to 55 ºC. The data obtained by viscometry showed that the intrinsic viscosity from the hydrolyzed polymers is larger than the precursor polymers at the same ionic strength. The comparison between the charged polymers showed that the polymer with higher hydrolysis degree has a more compact structure in formation water (AFS). The increase of temperature led to an enhanced reduced viscosity to the polymers in Milli-Q water (AMQ), although, in brine, only the unhydrolyzed polymer had an increase in the reduced viscosity with the temperature, and the hydrolyzed derivatives had a decrease in the reduced viscosity. The static light scattering (SLS) analyses in salt solutions evidenced a decrease of weight-average molecular weight (⎯Mw) with the increase of the hydrolysis degree, due to the reduction of the thermodynamic interactions between polymer and solvent, which was evidenced by the decrease of the second virial coefficient (A2). The polymers showed more than one relaxation mode in solution, when analyzed by photon correlation spectroscopy, and these modes were attributed to isolated coils and aggregates of several sizes. The aggregation behavior depended strongly on the ionic strength, and also on the temperature, although in a lower extension. The polymers showed large aggregates in all studied conditions, however, their solutions did not displayed a good increase in water viscosity to be used in enhanced oil recovery (EOR) processes

Remoção, por flotação, de óleo em águas produzidas na indústria de petróleo: eficiência e modelagem do processo

The separation oil-water by the use of flotation process is characterized by the involvement between the liquid and gas phases. For the comprehension of this process, it s necessary to analyze the physical and chemical properties command float flotation, defining the nature and forces over the particles. The interface chemistry has an important role on the flotation technology once, by dispersion of a gas phase into a liquid mixture the particles desired get stuck into air bubbles, being conduced to a superficial layer where can be physically separated. Through the study of interface interaction involved in the system used for this work, was possible to apply the results in an mathematical model able to determine the probability of flotation using a different view related to petroleum emulsions such as oil-water. The terms of probability of flotation correlate the collision and addition between particles of oil and air bubbles, that as more collisions, better is the probability of flotation. The additional probability was analyzed by the isotherm of absorption from Freundlich, represents itself the add probability between air bubbles and oil particles. The mathematical scheme for float flotation involved the injected air flow, the size of bubbles and quantity for second, the volume of float cell, viscosity of environment and concentration of demulsifier. The results shown that the float agent developed by castor oil, pos pH variation, salt quantity, temperature, concentration and water-oil quantity, presented efficient extraction of oil from water, up to 95%, using concentrations around 11 ppm of demulsifier. The best results were compared to other commercial products, codified by ―W‖ and ―Z‖, being observed an equivalent demulsifier power between Agflot and commercial product ―W‖ and superior to commercial product ―Z‖

Sistema microemulsionado: caracterização e aplicação na indústria de petróleo

Alkyl polyethoxylates are surfactants widely used in vastly different fields, from oil exploitation to pharmaceutical applications. One of the most interesting characteristics of these surfactants is their ability to form micellar systems with specific geometry, the so-called wormlike micelle. In this work, microemulsions with three distinct compositions (C/T = 40 %, 30 % and 25 %) was used with contain UNITOL / butanol / water / xylene, cosurfactant / surfactante (C/S) ratio equal to 0,5. The microemulsion was characterized by dynamic light scattering (DLS), capillary viscometry, torque rheometry and surface tensiometry experiments carried out with systems based on xylene, water, butanol (cosurfactant) and nonaethyleneglycolmonododecyl ether (surfactant), with fixed surfactant:cosurfactant:oil composition (with and without oil phase) and varying the overall concentration of the microemulsion. The results showed that a transition from wormlike micelles to nanodrops was characterized by maximum relative viscosity (depending on how relative viscosity was defined), which was connected to maximum effective diameter, determined by DLS. Surface tension suggested that adsorption at the air water interface had a Langmuir character and that the limiting value of the surfactant surface excess was independent of the presence of cosurfactant and xylene. The results of the solubilization of oil sludge and oil recovery with the microemulsion: C/S = 40%, 30% and 25% proved to be quite effective in solubilization of oil sludge, with the percentage of solubilization (%solubilization) as high as 92.37% and enhanced oil recovery rates up to 90.22% for the point with the highest concentration of active material (surfactant), that is, 40%.

Obtenção de polímeros graftizados de quitosana e estudo das propriedades físico-químicas para aplicação na indústria do petróleo

Chitosan is a biopolymer derived from the shells of crustaceans, biodegradable, inexpensive and renewable with important physical and chemical properties. Moreover, the different modifications possible in its chemical structure generate new properties, making it an attractive polysaccharide owing to its range of potential applications. Polymers have been used in oil production operations. However, growing concern over environmental constraints has prompted oil industry to search for environmentally sustainable materials. As such, this study sought to obtain chitosan derivatives grafted with hydrophilic (poly(ethylene glycol), mPEG) and/or hydrophobic groups (n-dodecyl) via a simple (one-pot) method and evaluate their physicochemical properties as a function of varying pH using rheology, small-angle Xray scattering (SAXS), dynamic light scattering (DLS) and zeta potential. The chitosan derivatives were prepared using reductive alkylation under mild reaction conditions and the chemical structure of the polymers was characterized by nuclear magnetic resonance (1H NMR) and CHN elemental analysis. Considering a constant mPEG/Chitosan molar ratio on modification of chitosan, the solubility of the polymer across a wide pH range (acidic, neutral and basic) could only be improved when some of the amino groups were submitted to reacetylation using the one-pot method. Under these conditions, solubility is maintained even with the simultaneous insertion of n-dodecyl. On the other hand, the solubility of derivatives obtained only through mPEG incorporation using the traditional methodology, or with the ndodecyl group, was similar to that of its precursor. The hydrophilic group promoted decreased viscosity of the polymer solutions at 10 g/L in acid medium. However, at basic pH, both viscosity and thermal stability increased, as well as exhibited a pronounced pseudoplastic behavior, suggesting strong intermolecular associations in the alkaline medium. The SAXS results showed a polyelectrolyte behavior with the decrease in pH for the polymer systems. DLS analyses revealed that although the dilute polymer solutions at 1 g/L and pH 3 exhibited a high density of protonated amino groups along the polymer chain, the high degree of charge contributed significantly to aggregation, promoting increased particle size with the decrease in pH. Furthermore, the hydrophobic group also contributed to increasing the size of aggregates in solution at pH 3, whereas the hydrophilic group helped reduce their size across the entire pH range. Nevertheless, the nature of aggregation was dependent on the pH of the medium. Zeta potential results indicated that its values do not depend solely on the surface charge of the particle, but are also dependent on the net charge of the medium. In this study, water soluble associative polymers exhibit properties that can be of great interest in the petroleum industry

Avaliação das propriedades físico-químicas de sistemas a base de carboximetilcelulose e poli (N-isopropilacrilamida) em soluções aquosas para aplicação na indústria do petróleo

Sustainable development is a major challenge in the oil industry and has aroused growing interest in research to obtain materials from renewable sources. Carboxymethylcellulose (CMC) is a polysaccharide derived from cellulose and becomes attractive because it is water-soluble, renewable, biodegradable and inexpensive, as well as may be chemically modified to gain new properties. Among the derivatives of carboxymethylcellulose, systems have been developed to induce stimuli-responsive properties and extend the applicability of multiple-responsive materials. Although these new materials have been the subject of study, understanding of their physicochemical properties, such as viscosity, solubility and particle size as a function of pH and temperature, is still very limited. This study describes systems of physical blends and copolymers based on carboxymethylcellulose and poly (N-isopropylacrylamide) (PNIPAM), with different feed percentage compositions of the reaction (25CMC, 50CMC e 75CMC), in aqueous solution. The chemical structure of the polymers was investigated by infrared and CHN elementary analysis. The physical blends were analyzed by rheology and the copolymers by UV-visible spectroscopy, small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and zeta potential. CMC and copolymer were assessed as scale inhibitors of calcium carbonate (CaCO3) using dynamic tube blocking tests and chemical compatibility tests, as well as scanning electron microscopy (SEM). Thermothickening behavior was observed for the 50 % CMC_50 % PNIPAM and 25 % CMC_75 % PNIPAM physical blends in aqueous solution at concentrations of 6 and 2 g/L, respectively, depending on polymer concentration and composition. For the copolymers, the increase in temperature and amount of PNIPAM favored polymer-polymer interactions through hydrophobic groups, resulting in increased turbidity of polymer solutions. Particle size decreased with the rise in copolymer PNIPAM content as a function of pH (3-12), at 25 °C. Larger amounts of CMC result in a stronger effect of pH on particle size, indicating pH-responsive behavior. Thus, 25CMC was not affected by the change in pH, exhibiting similar behavior to PNIPAM. In addition, the presence of acidic or basic additives influenced particle size, which was smaller in the presence of the additives than in distilled water. The results of zeta potential also showed greater variation for polymers in distilled water than in the presence of acids and bases. The lower critical solution temperature (LCST) of PNIPAM determined by DLS corroborated the value obtained by UV-visible spectroscopy. SAXS data for PNIPAM and 50CMC indicated phase transition when the temperature increased from 32 to 34 °C. A reduction in or absence of electrostatic properties was observed as a function of increased PNIPAM in copolymer composition. Assessment of samples as scale inhibitors showed that CMC performed better than the copolymers. This was attributed to the higher charge density present in CMC. The SEM micrographs confirmed morphological changes in the CaCO3 crystals, demonstrating the scale inhibiting potential of these polymers

A Construção/reconstrução das competências profissionais do assistente social diante da gestão do serviço social da indústria SESI a partir dos anos 90

L´étude du processus de construction / reconstruction des compétences de l´assistant social sous la gestion du SESI (Service Social de l´ Industrie), Natal/RN, dès la moitié des années 90 a réaffirmer la perspective que ce processus est le résultat de déterminations macrosociétaires qui sont présents, particulièrement au Brésil, aussi que, la façon par laquelle l´assistant social, le professionnel inscrit dans la division sociale et technique du travail, fait développer son perfectionement technique et intelectuel dans un milieu de nouvelles structures productives qui éxigent un nouveau profil du professionnel face à la crise du capital et de l´État. Cette recherche, de nature qualitative et quantitative, a eu lieu par de combinaisons de recherche bibliographique et empirique. Les sujets ont été huit assistants sociaux et six travailleurs administratifs du SESI, Natal/RN. Les donnés ont été obtenus par des interviews semi-structrées. On a analisé les changements qui sont arrivés dans les gestions du SESI et les compétences qui sont éxigées de l´assistant social ; l´influence du milieu socio-occupationel sur l´action professionnelle et sur le processus de construction/reconstruction de compétences; l´agrandissement de demandes institutionnelles pour l´assistant social par rapport à la prestation de services ; aussi que la constatation de l´importance de ce professionnel, sa hardiesse, mais aussi quelques limites et défis affrontés face à la qualification stimulé par le SESI, en amenant le professionnel dans un processus contradictoire de qualification et disqualification professionelle

CALV3 - Uma linguagem específica de domínio para segurança em sistemas corporativos: um estudo de caso sistemático na indústria

The academic community and software industry have shown, in recent years, substantial interest in approaches and technologies related to the area of model-driven development (MDD). At the same time, continues the relentless pursuit of industry for technologies to raise productivity and quality in the development of software products. This work aims to explore those two statements, through an experiment carried by using MDD technology and evaluation of its use on solving an actual problem under the security context of enterprise systems. By building and using a tool, a visual DSL denominated CALV3, inspired by the software factory approach: a synergy between software product line, domainspecific languages and MDD, we evaluate the gains in abstraction and productivity through a systematic case study conducted in a development team. The results and lessons learned from the evaluation of this tool within industry are the main contributions of this work