Surface Areas of Nitrated Hydrotalcites

Hydrotalcites in the nitrate form were prepared using microwave irradiation in the hydrotreatment step. The surface area (BET) of nitrated hydrotalcites was evaluated. Solids were characterized by atomic absorption, X-ray diffraction and BET analysis. Thermal pretreatment temperature determined the surface area of the hydrotalcites.     

Nature-Inspired Meta-Heuristics on Modern GPUs: State of the Art and Brief Survey of Selected Algorithms

Graphic processing units (GPUs) emerged recently as an exciting new hardware environment for a truly parallel implementation and execution of Nature and Bio-inspired Algorithms with excellent price-to-power ratio. In contrast to common multicore CPUs that contain up to tens of independent cores, the GPUs represent a massively parallel single-instruction multiple-data devices that can nowadays reach peak performance of hundreds and thousands of giga floating-point operations per second. Nature and Bio-inspired Algorithms implement parallel optimization strategies in which a single candidate solution, a group of candidate solutions (population), or multiple populations seek for optimal solution or set of solutions of given problem. Genetic algorithms (GA) constitute a family of traditional and very well-known nature-inspired populational meta-heuristic algorithms that have proved its usefulness on a plethora of tasks through the years. Differential evolution (DE) is another efficient populational meta-heuristic algorithm for real-parameter optimization. Particle swarm optimization (PSO) can be seen as nature-inspired multiagent method in which the interaction of simple independent agents yields intelligent collective behavior. Simulated annealing (SA) is global optimization algorithm which combines statistical mechanics and combinatorial optimization with inspiration in metallurgy. This survey provides a brief overview of the latest state-of-the-art research on the design, implementation, and applications of parallel GA, DE, PSO, and SA-based methods on the GPUs.     

Analysis of pentasodium triphosphate hydration kinetics

The present work analyzes the effect of various factors on the hydration of pentasodium triphosphate. The experimental method is based on application of the hydration test. Technical-quality products with different proportions of phase I and phase II have been used. The variables studied are phase I/phase II ratio, initial temperature, particle size, stirring rate and composition of the slurry (presence of hexahydrate crystals and water hardness). The results have been discussed according to a kinetics model that includes a series of stages of a physical nature (dissolution of anhydrous salt and the crystallization of the hexahydrate), as well as of a chemical nature (solvation of the ions in solution). Crystallization of the hexahydrate may be the controlling stage in the process.     

Functional properties of a protein product from Caryodendron orinocense (Barinas nut)

The functional properties of Caryodendron orinocense protein product were investigated and compared with those of soybean (Glycina maxima). The product protein content was 24.47 g/100 g (Nx6.25). Solubility increased at both sides of the isoelectric point (pH 4.0) and with increased NaCl concentration up to 0.5M. Compared with soybean flour (50% protein), the protein product exhibited higher water and oil absorption, but lower emulsifying activity, emulsion stability, foaming capacity, and foam stability, the last one increase at higher pH. Emulsifying activity, foaming capacity, and foam stability were ionic strength dependent. C. orinocense protein product increased its emulsifying activity steadily from 0.05M to 0.75M NaCl, while it remained almost constant for soybean flour. Foaming capacity increased drastically at pH 10. The minimum time and concentration to form a gel was 20% in 4 min and 10% in 8 min for the Caryodendron protein product and soybean flour, respectively. The bulk density was 0.5056+/-0.0041 g/mL.     

Impregnation of X Zeolite with Alkaline Hydroxide During the Synthesis

Enhancement of the basic properties of the X zeolite with FAU framework has been carried out during synthesis, without further treatment such as ion-exchange or impregnation. Control of the washing stage enables retention of the optimum amount of alkaline hydroxides, which increases the basic catalytic activity of X zeolite in the alkylation of toluene. This alkaline hydroxides neither affect the FAU framework nor the silicon/aluminium molar ratio of the X zeolite. The optimum (Na + K)/Al molar ratio of the improved catalyst was 1.06 corresponding to a washing volume of 200 mL. This X zeolite presented better catalytic activity than a cesium-zeolite prepared by ion-exchange. The presence of hydroxysodalite impurity in the X zeolite increased the amount of impregnated alkaline hydroxides but not the catalytic activity. The present study shows that it is possible to increase the basic properties of the X zeolite directly in the synthesis process.     

Scrolls and nested tubes in multiwall carbon nanotubes

Recent high-resolution transmission electron microscopy (HREM) studies of multiwalled carbon nanotubes (MWCNTs) reveal a class of defects analogous to edge dislocations in a crystal. These defects are believed to mark the transition from scrolls on one side to nested tubes on the other. On the tube side, layer spacing becomes irregular. Analysis of the helicity of the tubes shows a strong correlation between diameter and helicity. This suggests that the organizing principle for the tubes is not Van der Waals forces, as in the case of graphite or turbostratic carbon, but preservation of helicity. Based on these observations and total energy calculations, the authors speculate that graphene monolayers initially form scrolls and subsequently transform into multiwall nanotubes through the progression of defects. Scrolls and nested tubes thus coexist within a single MWNT.     

Stretching and deformation vibrations of CH2, C(CH3) and O(CH3) groups of poly(methyl methacrylate)

Infrared and Raman spectra of atactic PMMA and infrared spectra of stereoregular PMMA and of its four deuterated derivatives

, were measured. They were used to assign the bands of stretching and deformation vibrations of CH₂, CCH₃ and OCH₃ groups in the infrared and Raman spectra and to discuss the effect of stereoregularity on these bands in the infrared spectra.     

Relation between erythrocyte free protoporphyrins and usual iron intake in a group of University of Buenos Aires students

In order to analyze the interrelationships between free erythrocyte protoporphyrins and the usual iron intake in adult students, biochemical, and hematological values, and dietary daily intake, obtained using the recall method during seven days, were studied. Hematocrit (Hto.), hemoglobin (Hb) and free erythrocyte protoporphyrins (FEP) were determined in a group of 145 female university students, healthy according to the standard parameters of the Buenos Aires University Health Department. Mean iron intake was 23.0 +/- 1.5 mg per day, about 44% being provided by animal sources; 74.5% of the population was within the recommended daily intake according to FAO/WHO; only 0.7% of the population did not cover protein requirements while 35% did not cover energy needs. Hto. and Hb were below normal levels in 7.8% of the population when compared with standards according to ICNND. To obtain information about normal values to FEP, expressed as microgram/100 ml red cells (FEP% r.c.) and FEP/Hb ratio, the group of students with adequate intake of energy and proteins who had normal values for Hb and Hto. was selected. This group, including 94 women, had a mean FEP% r.c. of 15.71 +/- 7.26 and a mean FEP/Hb ratio of 0.44 +/- 0.21. There was observed an inverse correlation between FEP% r.c. and FEP/Hb with total iron intake (r = 0.80 and r = 0.78, respectively) and between FEP% r.c. and Hb concentration (r = 0.81). These results confirm the usefulness of the free erythrocyte protoporphyrins determination as a good index of iron stores and usual intake of this population.     

Effect of temperature on the separation of some Δ9-cis-trans isomers of methyl esters of fatty acids by open tubular gas chromatography

The influence of temperature on the gas chromatographic separation ofcis-trans isomers of the methyl esters of some monounsaturated fatty acids was studied on capillary columns coated with Apiezon L, BDS and DEGS. As far as methyl oleate and methyl elaidate are concerned, the separation is better at lower temperatures on Apiezon L (180–210 C) and at higher temperatures on polyester phases (BDS, DEGS; 150–180 C). The influence of temperature on the separation ofcis-trans isomers on the three stationary phases under study is explained by the higher values of δECL/δt forcis isomers. The variation of the equivalent carbon chain length with temperature can be used for the identification ofcis-trans isomers in natural mixtures.