SIMULATION OF THIN-FILM DEODORIZERS IN PALM OIL REFINING

As the need for healthier fats and oils (natural vitamin and trans fat contents) and interest in biofuels are growing, many changes in the world's vegetable oil market are driving the oil industry to developing new technologies and recycling traditional ones. Computational simulation is widely used in the chemical and petrochemical industries as a tool for optimization and design of (new) processes, but that is not the case for the edible oil industry. Thin-film deodorizers are novel equipment developed for steam deacidification of vegetable oils, and no work on the simulation of this type of equipment could be found in the open literature. This paper tries to fill this gap by presenting results from the study of the effect of processing variables, such as temperature, pressure and percentage of stripping steam, in the final quality of product (deacidified palm oil) in terms of final oil acidity, the tocopherol content and neutral oil loss. The simulation results have been evaluated by using the response surface methodology. The model generated by the statistical analysis for tocopherol retention has been validated by matching its results with industrial data published in the open literature.

PRACTICAL APPLICATIONS

This work is a continuation of our previous works ( Ceriani and Meirelles 2004a, 2006 ; Ceriani et al. 2008 ), dealing with the simulation of continuous deodorization and/or steam deacidification for a variety of vegetable oils using stage-wised columns, and analyzing both the countercurrent and the cross-flow patterns. In this work, we have studied thin-film deodorizers, which are novel equipment developed for steam deacidification of vegetable oils. Here, we highlight issues related to final oil product quality and the corresponding process variables.     

High-gain observers for non-linear systems

State estimation for non-linear dynamic systems is discussed. A high-gain injection from the output variables is used to attenuate to any desired degree, the effect of the non-linear terms on the estimation errors, which can be made arbitrarily small, from a particular observable form. Some Liapunov arguments are used to study the stability properties of the resulting error dynamics. It is shown that any completely observable multi-input multi-output non-linear system, not necessarily linear in the input variables, can be transformed, by means of a change of coordinates depending on the input variables, in such an observable form. In particular, the solvability of partial differential equations is not needed for the design of this transformation.     

DEVELOPMENT POLICIES FOR MEXICAN PETROCHEMICALS

After a decade of rapid development of an indigenous petrochemicals industry Mexico still relies on imported petrochemicals. To promote further participation of the private sector the Mexican government subsidizes the purchase of energy and basic raw materials. We analyze the impact of such a development policy on the growth of a balanced chemical industry, on the reduction of the dependence on imported chemicals, and on the technology selection by the industry. We then analyze the effect of insufficient investment capital and the possibility of entering the world markets for the sale of surplus petrochemicals.     

Cooperative research in underwater robot mission-level programming methodologies

Programming autonomous vehicles to accomplish complex missions is a complicated task for which the development of control architectures is of prime importance. The goal of this paper is to describe the accomplishments of both French and American teams within a cooperative research program focused on the development of high-level control of semi-autonomous underwater vehicles. In particular, two different mission-programming methodologies are examined in the context of the requirements of a generic, reactive and complex underwater mission. The French team uses a combination of the ESTEREL synchronous programming language and the PIRRAT real-time control library to implement a methodology derived from the ORCCAD programming system. The approach taken by the American team builds a trilevel hybrid architecture using the CONTROLSHELL real-time software development environment. The details of each methodology are highlighted through the presentation of the high-level programs designed by each team using their approach to control an underwater robot to perform a multiphased underwater mission. The utility of both programming methodologies was verified through the successful completion of those missions in experimental demonstrations by the French VORTEX and American OTTER autonomous underwater vehicles.     

Computation of the RCS of coated objects by a generalized PTD approach

We consider the diffraction of an incident plane wave by 3D objects, such as missiles. These objects can be either perfectly conducting or coated with dielectric or magnetic coatings. Their shape, usually described in cad format, can be quite complex, with reentrant cavities, wings, ..., such that multiply reflected, reflected diffracted, and multiple diffracted rays exists. Morover, as these objects are designed to have a low rcs, these rays can be, for some angles of incidence, the main contributions to thercs. ptd is an efficient technique to compute thercs of complex objects, that has the desirable property of providing bounded results for any angle of incidence and observation. However, this theory has been mainly applied to perfectly conducting objects, the fringe wave is computed for wedge-like discontinuities, it does not include multiple phenomena. We have generalizedptd in three directions. First, we have extended the fringe wave concept to the case of an edge satisfying an impedance boundary condition. Second, we have computed diffraction by rounded edges or by tips by using an hybrid asymptotic-MoM method. Third, we have included multiply reflected or diffracted rays. We present some examples ofrcs and comparison with other methods.     

EFFECT OF MODIFIED ATMOSPHERE STORAGE ON HAZELNUT QUALITY

Hazelnut quality was studied after storage in selected modified atmosphere conditions. Hazelnuts of the Negret cultivar collected in Tarragona, Spain, were used in the experiments. The shelled and unshelled hazelnuts were stored with different oxygen concentrations (1%, 5%, 10% and 20% O₂) at two different temperatures (7C and 25C). The quality of the hazelnuts during storage was monitored by determining the peroxide value, acid value, K₂₃₂ and K₂₇₀ indices, percentage of unsaturated fatty acids and sensory analysis of the hazelnuts. It was observed that after one year storage period, none of the storage modes had given rise to significant rancidity. It was also confirmed that the shell protected the hazelnut from oxidative deterioration. Nevertheless, storage in atmospheres with oxygen levels lower than 10%, autoxidation was significantly reduced and the low temperature delayed lipid rancidity.     

DNA mismatch repair gene methylation in gastric cancer in individuals from northern Brazil

Gastric cancer is one of the most common malignancies. DNA methylation is implicated in DNA mismatch repair genes deficiency. In the present study, we evaluated the methylation status of MLH1, MSH2, MSH6 and PMS2 in 20 diffuse- and 26 intestinal-type gastric cancer samples and 20 normal gastric mucosal of gastric cancer patients from Northern Brazil. We found that none of the nonneoplastic samples showed methylation of any gene promoter and 50% of gastric cancer samples showed at least one methylated gene promoter. Methylation frequencies of MLH1, MSH2, MSH6 and PMS2 promoter were 21.74%, 17.39%, 0% and 28.26% respectively in gastric cancer samples. MLH1 and PMS2 methylation were associated with neoplastic samples compared to nonneoplastic ones. PMS2 methylation was associated with diffuse- and intestinal-type cancer compared with normal controls. Intestinal-type cancer showed significant association with MLH1 methylation. Diffuse-type cancer was significantly associated with MSH2 methylation. Our findings show differential gene methylation in tumoral tissue, which allows us to conclude that methylation is associated with gastric carcinogenesis. Methylation of mismatch repair genes was associated with gastric carcinogenesis and may be a helpful tool for diagnosis, prognosis and therapies. However, MSH6 does not seem to be regulated by methylation in our samples.