Characterization of Physico-Chemical Properties of Oil/Water Systems: Interfacial Behavior Prediction

The tractability of petroleum is intimately related to the type of emulsion that is formed during its production. The characteristics of water/oil and oil/water emulsions depend on some factors such as the density and the composition of the oil. In this work, the properties of oils coming from the Campos Basin, Brazil, were evaluated by means of water-in-oil emulsion physico-chemical, interfacial, and characterization tests. Such properties have been correlated with the tractability of the petroleum in order to establish a behavior prediction method based on the properties of such petroleum. The main tool used in this work was the chemiometry technique. Through this method, it was possible to conclude that density, viscosity, surface tension, and nickel content were the properties that influenced the separation of the oils. Density, pour point, initial temperature of crystal formation (TIAC), characterization factor, and nitrogen content were the properties that influenced the diameter of the emulsion drops.     

Ovarian recovery after total body irradiation and allogeneic bone marrow transplantation: long-term follow up of 79 females

Seventy-nine females undergoing allogeneic BMT following conditioning with total body irradiation (TBI), were prospectively followed between March 1983 and March 1992 with regular gynaecological examinations, including plasma levels of luteinising hormone (LH), follicle stimulating hormone (FSH), 17-beta oestradiol (E2) and pelvic ultrasonography. The end-points of this study were the following: (1) early and late effects of TBI on ovarian function, (2) compliance and results of hormonal replacement therapy (HRT), and (3) predictive events for ovarian recovery. During the first year post-BMT most adult women complained of vasomotor and/or genitourinary tract symptoms. These were associated with decreased E2 and increased LH-FSH plasma levels and a deterioration in their sexual life (94% of sexually active women). Forty-nine adult females were selected to receive systemic hormonal replacement therapy (HRT), consisting of cyclic transdermal oestrogens plus medroxyprogesterone acetate (MPA) or cyclic oral therapy with low doses of conjugated oestrogens and MPA: these patients were selected on the basis of age (< 45 years), absence of medical contraindications or subjective refusal. Compliance and tolerability were overall good: most women (65%) never stopped HRT; this was discontinued in 14 patients for medical reasons and in 3 because of refusal. Forty-three females completed 6 months of HRT: vasomotor symptoms disappeared in 91% of 58 women who previously referred these symptoms. Improvement of genitourinary symptoms was seen both with local and systemic hormonal therapy. However sexual symptoms were reduced in 21 of 26 women (81%) given HRT compared with 8 of 19 (42%) women given local treatment (p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

Secondary dendrite arm spacing and solute redistribution effects on the corrosion resistance of Al–10 wt% Sn and Al–20 wt% Zn alloys

In general, aluminum alloys provide the most significant part of all shaped casting manufactured. An optimum range of properties can be obtained as a function of different cooling rate processes, such as sand, plaster, investment, permanent molds and die castings. It is well known that the dendritic network affects not only the mechanical properties but also the corrosion resistance. However, the literature is scarce on reports concerning the influences of dendrite arm spacing on corrosion resistance and mechanical behavior. The aim of this study is to investigate the influence of as-cast microstructure features, i.e., dendrite arm spacing and solute redistribution on the corrosion resistance of samples of aluminum alloys. In order to investigate the electrochemical behavior of solute and solvent of different aluminum systems, samples with the same order of magnitude of dendritic spacings were analyzed to permit comparison between Al–10 wt% Sn and Al–20 wt% Zn alloys. A casting water-cooled assembly promoting upward directional solidification was used in order to obtain controlled casting samples of these alloys. In order to characterize the dendritic structure, longitudinal sections from the directionally solidified specimens were analyzed by using optical and electronic microscopy techniques. The corrosion resistance was analyzed by both the electrochemical impedance spectroscopy technique and Tafel extrapolation method conducted in a 3% NaCl solution at room temperature. Although both systems present an Al-rich dendritic matrix, different responses to corrosive action as a function of dendritic spacing have been detected.     

Prediction of the percentages of cows', goats' and ewes' milk in “Iberico” cheese by electrophoretic analysis of whey proteins

Stepwise multiple linear regression (SMLR) and principal components regression (PCR) have been used to predict the percentages of cows', goats' and ewes' milk in “Iberico” cheese, using the results obtained by electrophoretic analysis (PAGE and IEF) of whey proteins, using standard cheeses. Similar predictions of the percentages of milks from the three species were obtained when either SMLR or PCR were applied to the electrophoretic data, i.e. the optical intensity of the electrophoretic bands (PAGE or IEF) of the whey proteins. The root mean square error of prediction in cross-validation (RMSEPCV) was lower than 4% in all cases.     

Group transfer polymerization and its use in water based pigment dispersants and emulsion stabilizers

Group transfer polymerization (GTP) can be used to make AB diblock acrylic polymers. It provides excellent control of the structure of these polymers. With a hydrophilic B block, these polymers have been used to prepare water based emulsions, pigment dispersions, and slurries. These systems have property advantages over emulsions and dispersions made with conventional stabilizers. These advantages include increased stability, smaller particle sizes, lower viscosities, and less moisture sensitivity. The structure of the AB diblock polymer affects the properties of both the pigment dispersion and the emulsion particle. The composition, size and ratio of each block affect the overall quality. For aqueous systems, a balance of hydrophobic ‘A’ blocks and very hydrophilic ‘B’ blocks is needed for optimum properties. The hydrophobic ‘A’ blocks, which are homo or copolymers of methacrylate monomers (such as butyl or ethylhexyl methacrylate), are surface active and can associate with either pigment or emulsion polymer surfaces. The hydrophilic ‘B’ blocks, which are neutralized acid or amine containing copolymers, provide both ionic as well as steric stabilization in water-borne systems.     

Whiteness Constraints in a Unified Variational Framework for Image Restoration

We propose a robust variational model for the restoration of images corrupted by blur and the general class of additive white noises. The key idea behind our proposal relies on a novel hard constraint imposed on the residual of the restoration, namely we characterize a residual whiteness set to which the restored image must belong. As the feasible set is unbounded, solution existence results for the proposed variational model are given. Moreover, based on theoretical derivations as well as on Monte Carlo simulations, we provide well-founded guidelines for setting the whiteness constraint limits. The solution of the non-trivial optimization problem, due to the non-smooth non-convex proposed model, is efficiently obtained by an alternating directions method of multipliers, which in particular reduces the solution to a sequence of convex optimization subproblems. Numerical results show the potentiality of the proposed model for restoring blurred images corrupted by several kinds of additive white noises.     

Nash equilibria in location games on a network

OR Spectrum - We study the existence and determination of Nash equilibria (NE) in location games where firms compete for the market with the aim of profit maximization. Each competing firm locates...