A mixture of orange vesicle flour, commercial nixtamalized corn flour and potato starch was extruded using a Brabender Laboratory single screw extruder (2:1 L/D). The resulting pellets were expanded by microwaves. Expansion index, bulk density, penetration force, carotenoid content, and dietary fiber were measured for this third-generation snack and optimum production conditions were estimated. Response surface methodology was applied using a central composite rotatable experimental design to evaluate the effect of moisture content and extrusion temperature. Temperature mainly affected the expansion index, bulk density and penetration force, while carotenoids content was affected by moisture content. Surface overlap was used to identify optimum processing conditions: temperature: 128-130°C; moisture content: 22-24 %. Insoluble dietary fiber decreased and soluble dietary fiber increased after extrusion.

No abstract

A diffusion model was suggested to analyse the growth kinetics of Fe 2 B layers formed on AISI D2 steel by the pack-boriding process. It was used to estimate the boron diffusion coefficients of Fe 2 B in the temperature range of 1123-1273 K by applying the mass balance equation at the (Fe 2 B/ substrate) interface. The proposed model was validated experimentally at 1253 K for a treatment time of 5 h by comparing the experimental Fe 2 B layer thickness with the predicted value. Furthermore, the pack-borided AISI D2 steel was characterised by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analysis. A contour diagram describing the evolution of Fe 2 B layer thickness as a function of the process variables was also proposed. In addition, the boron activation energy for AISI D2 steel was found to be equal to 201?50 kJ mol 21 , on the basis of our experimental results.

This work shows the physicochemical behavior of two different diatoms from the country of Mexico (State of Jalisco and Hidalgo) with similar compositions. These were used to eliminate toxic cations from a synthetic solution containing 5.270 mg As 3+ /L; 4.280 mg Ag + /L; 3.950 mgNi 2+ /L; 4.090 mg Cr 6+ /L; and 4.081 mg Pb 2+ /L. These diatoms were used as filters, and the quantity of cations remaining in the solution after filtering was measured. According to the most important results found, for the recovery of metals, both minerals achieved arsenic, silver, lead, and nickel recoveries up to 95%, and lower than 10% for chromium. This could be due to the absence of an environment to reduce Cr 6+ to Cr 3+ . On the other hand, it was observed that there was no selectivity during the recovery of the other cations present in the solution. According to efficiency of interchange, the mineral from Hidalgo is slightly better than the mineral from Jalisco for the removal of arsenic, lead, and silver. For nickel, and particularly Cr 6+ , the efficiency is higher for the sample from Jalisco.

No abstract

Cu, Pb, and Hg concentrations were determined in surface sediment samples collected at three sites in San Jorge Bay, northern Chile. This study aims to evaluate differences in their spatial distribution and temporal variability. The highest metal concentrations were found at the site "Puerto", where minerals (Cu and Pb) have been loaded for more than 60 years. On the other hand, Hg does not pose a contamination problem in this bay. Cu and Pb concentrations showed significant variations from 1 year to another. These variations seem to be a consequence of the combination of several factors, including changes in the loading and/or storage of minerals in San Jorge Bay, the dredging of bottom sediments (especially at Puerto), and seasonal changes in physical-chemical properties of the water column that modify the exchange of metals at the sediment-water interface. Differences in the contamination factor and geoaccumulation index suggest that pre-industrial concentrations measured in marine sediments of this geographical zone, were better than geological values (average shale, continental crust average) for evaluating the degree of contamination in this coastal system. Based on these last two indexes, San Jorge Bay has a serious problem of Cu and Pb pollution at the three sampling locations. However, only Cu exceeds the national maximum values used to evaluate ecological risk and the health of marine environments. It is suggested that Chilean environmental legislation for marine sediment quality--presently under technical discussion--is not an efficient tool for protecting the marine ecosystem.

Metal toxicity can cause hematologic abnormalities and hemolysis. To evaluate the relationship of anemia with metal contamination in children, the following elements were quantified in dry blood: silicon, chromium, lead, titanium, vanadium, nickel, arsenic, manganese, and cadmium. A total of 88 samples of anemic children and 208 of non-anemic children aged 6-12 years were analyzed. Lead (35.1%), chromium (24.3%), vanadium (24.3%), nickel (45.6%), and silicon (48.6%) were identified in the samples, with titanium only detected in anemic children. The average level of arsenic was higher in anemic than non-anemic children (0.041 ± 0.11 wt% vs 0.014 ± 0.05 wt%, p < 0.05) and correlated with the concentration of hemoglobin (r = -0.441, p < 0.01). In conclusion, heavy metals, which confer a health risk, were detected in the dry blood of the children evaluated, and the levels of arsenic and titanium were found to be related to anemia.

No abstract