In vitro release profiles of β-carotene encapsulated in PHBV by means of supercritical carbon dioxide micronization technique

The main objective of this work was to investigate the characteristics of the in vitro release of β-carotene encapsulated in poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) using the solution enhanced dispersion by supercritical fluids (SEDS) technique. The release tests were performed using encapsulated complex with solute loading from 2.24 to 27.5% and encapsulation efficiency from 7.75 to 55.54%. The release profile assays were performed in ethyl acetate, n-hexane and anhydrous ethanol, and monitored by UV-vis spectrophotometer concentration analysis. Results indicated higher initial release rates in ethyl acetate and in n-hexane, with cumulative release percentage varying from 31.50 to 69.58% and from 42.08 to 55.96%, respectively. For anhydrous ethanol the maximum concentration was reached at 180 min, 300 min and 10 days, depending on the initial amount of β-carotene, with cumulative release ranging from 45.27 to 88.22%. In general, the β-carotene release can be controlled by the organic solvent used and by the initial amount of solute encapsulated, aspects that help the selection of the conditions to achieve the desired release profiles for a specific application.     

Analysis of the particle swarm algorithm in the optimization of a three-phase slurry catalytic reactor

The Particle Swarm Optimization (PSO) method was employed to optimize an industrial chemical process characterized by being difficult to be optimized by conventional deterministic methods. The chemical process is a three phase catalytic slurry reactor (tubular geometry) in which the reaction of the hydrogenation of o-cresol producing 2-methyl-cyclohexanol is carried out. The optimization problem was formulated considering as input variables the operating conditions of the reactor and as objective function the maximization of productivity, subject to the environmental constraint of conversion. The process was represented by a multivariable non-linear rigorous mathematical model and in order to solve the optimization problem, the performance of the PSO algorithm was evaluated considering four sets of parameters values suggested by the literature. PSO demonstrated to be efficient and robust to solve the constrained optimization problem, independently of the values of the PSO parameters. The solution of the rigorous mathematical model of the reactor was associated with a high computational burden, and although the PSO algorithm presented high rate of convergence, the attempt to make possible the optimization in a timeframe suitable to real time applications failed because the algorithm lost robustness (fraction of the number of runs the algorithm reached the optimization goal) when run with a reduced number of function evaluations. Therefore, if this type of application is desired, simplified mathematical models with fast and simple numerical methods must be preferred.     

Comparative determination of TiO2 surface free energies for adhesive bonding application

The development of durable bonds using titanium adherens has been investigated from the point of view of surface energy theoretical models measurements. The traditional Chromium Acid Anodization, which provides excellent durability, has to be phased out due to the use of hazardous Cr (VI) in the bath and as a result, special attention is paid to the sodium hydroxide anodizing and other alkaline chemical etchers. There are hardly any references on the surface free energy of adhesive titanium oxide coatings and therefore the objective of this work was to evaluate the surface and interface energy parameters of the various types of alkaline chromate free surface treatments using Neumann, Fowkes and van Oss–Chaudhury–Good methods in order to determine which method provides greatest differentiation between the coatings. Results show that Fowkes method produced the greatest variance in surface energies of the compared surface treatments and hence can be considered as better suited for more accurate discrimination between the oxide surface treatments on Ti–6Al–4V alloy. Although, in the case of model liquids, i.e. water and diiodomethane, the trends obtained for contact angles, surface energies, works of adhesion and solid/liquid interface energies all correlated between each other, a disagreement between the trends of solid/liquid interface energies calculated using Fowkes and van Oss–Chaudhury–Good methods for surface treatment/adhesive resin was obtained. In case of real adhesive systems, the use of work of adhesion appears more adequate in order to discriminate the surface treatments. Based on these findings the anodization in the tested alkaline bath after a previous alkali etching in the same bath is recommended, although adhesion test has to be still performed.     

Optimal design of extractive distillation columns—A systematic procedure using a process simulator

The separation of binary mixtures which form azeotropes is not possible through conventional distillation and they are usually separated by extractive or azeotropic distillation. The optimization of extractive distillation columns is usually performed using a process simulator; however, normally, the result is only obtained after several simulations and the simultaneous analysis of several graphs. This paper sets out to present a systematic procedure, using a process simulator (Aspen Plus^®), in order to obtain the optimum condition for extractive distillation columns. The optimization achieved is characterized by the fact that it is not necessary to perform various simulations, and it also avoids the simultaneous analysis of dozens of curves. The dehydration of aqueous mixtures of ethanol using ethylene glycol as solvent was the system chosen as a case study.     

Self-stratifying antimicrobial polyurethane coatings

In this work antimicrobial polyurethane coatings were prepared aiming at self-stratification. A hydroxyl end-capped liquid oligoester consisting of three equimolar diacids and an excess of 1,4-butanediol has been synthesized by a condensation reaction. A set of quaternary ammonium compounds (QACs) which are well known contact killers, was synthesized via a straightforward quaternization reaction. These synthesized precursors were later covalently bonded to the polymer network by addition of a polyisocyanate crosslinker resulting in antimicrobial polyurethane coatings. Self-stratification was confirmed by dynamic contact angle analysis and X-ray photoelectron spectroscopy. The final films showed strong antimicrobial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli type bacteria.     

Antioxidant intake among Brazilian adults - The Brazilian Osteoporosis Study (BRAZOS): a cross-sectional study

Background  

Antioxidant nutrient intake and the lesser formation of free radicals seem to contribute to chronic diseases. The aim of the present study was to evaluate the intake profile of the main dietary antioxidants in a representative sample of the adult Brazilian population and discuss the main consequences of a low intake of these micronutrients on overall health.     

Leaf Chemistry and Foliage Avoidance by the Thrips <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis> and <Emphasis Type="Italic">Heliothrips haemorrhoidalis</Emphasis> in Glasshouse Collections

Observational studies on foliage avoidance by the polyphagous thrips species Frankliniella occidentalis (Pergande) and Heliothrips haemorrhoidalis (Bouché) (Thysanoptera: Thripidae) identified six non-host species (Allagopappus dichotomus (Asteraceae), Gardenia posoquerioides (Rubiaceae), Plectranthus aff. barbatus, Plectranthus strigosus, Plectranthus zuluensis (Lamiaceae), and Sclerochiton harveyanus (Acanthaceae) among plants growing within a major glasshouse botanical collection. The effects of sequentially obtained acetone and aqueous methanol leaf extracts on mortality in first instar Frankliniella occidentalis were assessed. The acetone leaf extract of Sclerochiton harveyanus, which had the highest activity against the thrips, yielded four new iridoids, sclerochitonosides A–C, and sclerochitonoside B 4′-methyl ether. Mortality of F. occidentalis was increased on exposure to all four iridoids, and the most active iridoid was sclerochitonoside A (8-epiloganic acid 4′-hydroxyphenylethyl ester). Choice experiments demonstrated that this compound did not significantly deter H. haemorrhoidalis from treated leaf surfaces. The significance of iridoids in the defense mechanism of plants against thrips is discussed.     

SEM study of the morphology of asymmetric cellulose acetate membranes produced from recycled agro-industrial residues: sugarcane bagasse and mango seeds

Cellulose, obtained both from sugarcane bagasse and mango seeds, was used for synthesizing cellulose acetate in order to produce asymmetric membranes. These were compared to membranes of commercial cellulose acetate (Rhodia). All produced membranes were asymmetric, characterized by the presence of a dense skin and a porous support. Differences regarding the morphology of the surfaces as well as of the porous support can be noticed. Scanning Electron Microscopy (SEM) showed that the morphology of the superficial layer, responsible for transport, depends on the different lignin content of the starting material and also on the viscosity average molecular weight of the cellulose acetates produced from sugarcane bagasse, mango seed, and Rhodia’s commercial cellulose acetate.     

Validation of the Langevin particle dispersion model against experiments on turbulent mixing in a T-junction

The fluctuating fluid velocities seen by particles entrained in a turbulent fluid have recently been modeled using a stochastic model based normalized Langevin Continuous Random Walk (CRW). This model has been quite successful in predicting particle dispersion in mildly complex flows. In the present study, we aim at validating the CRW model further against data collected in a challenging 3D geometry. We consider turbulent fluid mixing downstream of a T-junction using a hybrid Euler-Lagrange approach whereby tracer particle trajectories are computed and mixing of the streams deduced from the relative concentration of particles originating from the two inlet branches of the Tee. In a first simulation, RANS Reynolds Stress Model (RSM) is used to obtain the mean flow field, whereas the fluid fluctuations are specified from a CRW. Simulation results are compared to experimental data on mixing of two isothermal streams consisting of tap and de-ionized water, respectively. It is found that RSM-CRW yields strong under-prediction of the mixing. Closer look at the results shows that the Reynolds stresses, which are required inputs to the CRW, are poorly predicted with RSM. Detached Eddy Simulations (DES) are subsequently performed to provide the mean flow field, and the DES-CRW model predictions are found to compare quite well with the experimental data.     

Influence of pigment on biodeterioration of acrylic paint films in Southern Brazil

Biodeterioration of paint films leads to loss of durability and increased repainting costs. The influence of pigments on the biodeterioration of architectural paint films in the city of Florianópolis, Brazil, was evaluated using ten differently colored acrylic paint films exposed to the environment for 34 months. Fouling (biofilm formation) on the surfaces was assessed macroscopically, using British Standard BS 3900/1989 G6, and microscopically. After 20 months, major colonizers were bacteria and fungi, with some cyanobacteria and few algae; north-facing suede and peach and south-facing ice colors showed 100% cover at this time. The least affected color at all times was blue, with a maximum of 30% cover on south-facing panels after 34 months. North-facing panels were generally more fouled than South-facing. Blue, red, and ceramic colors always performed best. Resistance to fouling may have been due to copper in blue and acidity from sulfur oxides in ceramic pigments. Pigments may prolong paint film life and reduce the need for biocides.