Synthesis of iron-doped TiO2 nanoparticles by ball-milling process: the influence of process parameters on the structural,optical, magnetic,and photocatalytic properties

Titanium dioxide (TiO₂) absorbs only a small fraction of incoming sunlight in the visible region thus limiting its photocatalytic efficiency and concomitant photocatalytic ability. The large-scale application of TiO₂ nanoparticles has been limited due to the need of using an ultraviolet excitation source to achieve high photocatalytic activity. The inclusion of foreign chemical elements in the TiO₂ lattice can tune its band gap resulting in an absorption edge red-shifted to lower energies enhancing the photocatalytic performance in the visible region of the electromagnetic spectrum. In this research work, TiO₂ nanoparticles were doped with iron powder in a planetary ball-milling system using stainless steel balls. The correlation between milling rotation speeds with structural and morphologic characteristics, optical and magnetic properties, and photocatalytic abilities of bare and Fe-doped TiO₂ powders was studied and discussed.     

Cell wall polysaccharides implied in green olive behaviour during the pitting process

Olive fruits processed as “Spanish green olives” were sorted into two batches depending on their pitting behaviour: those that broke under punch pressure, and those that were pitted without damage. Cell wall polysaccharides from both batches were isolated. The main changes were lower amounts of carbonate-soluble and 24 % KOH-soluble polysaccharides and a higher proportion of 4% KOH-soluble polysaccharides in broken olives. The carbonate-soluble fraction from broken olives was poorer in homogalacturonans, polysaccharides that could help in increasing texture. The 24% KOH-soluble fraction from the same olive batch was poorer in xylans and xyloglucans, the former being present in a higher proportion in the 4% KOH-soluble fraction and the last in cellulose residue. The new xylans of the 4% KOH-soluble fraction were of high (around 250 kDa) and low (6–40 kDa) molecular weights. Carbonate-soluble and 24% KOH-soluble fractions are very important in maintaining cell wall structure, which is responsible for vegetable product firmness. Received: 28 September 1999     

Different cell disruption methods for obtaining carotenoids by Sporodiobolus pararoseus and Rhodothorula mucilaginosa

Food Science and Biotechnology - Since carotenoids are synthesized inside the cell, it is desirable to find an efficient method to extract carotegenic pigments. This study aimed at comparing the...     

Using a Strong Anion-Exchange Resin to Deacidify Red Palm Oil

This work aims to evaluate the use of an alternative process to deacidify palm oil using a strong anion-exchange resin (Amberlyst A26 OH). The effects of the feed flow rate and the free fatty acids content in the feed stream were investigated by measuring breakthrough curves for bleached palm oil dissolved in n-propanol. The resin had sufficient capacity and affinity to remove palmitic and oleic acids (98–99 %). The bed utilization efficiency can be optimized by choosing lower flow rates for oils with low levels of acidity, while higher flow rates can be used for oils with higher free fatty acids content. The ion-exchange process can be used to obtain deacidified red palm oil, while preserving carotenoid and tocopherol/tocotrienol content. This alternative process has the advantage of occurring under mild conditions (44.0 ± 0.8 °C and atmospheric pressure) when compared with the conditions used in molecular distillation (150.0–170.0 °C and 2.7–3.3 Pa).     

The Effect of the Molecular Mass on the Sputtering of Si,SiC, Ge,and GaAs by Electrosprayed Nanodroplets at Impact Velocities up to 17 km/s

Electrosprayed nanodroplets impacting on covalently bonded materials at velocities of a few kilometers per second strongly modify their surfaces by sputtering atoms, amorphizing the region surrounding the impact, and carving craters of comparable size. This article investigates the effects of the projectile's molecular mass on the phenomenology of the impact on Si, SiC, Ge, and GaAs at impact velocities significantly higher than previously studied. An appropriate range of molecular mass is covered by electrospraying the ionic liquids ethylammonium nitrate, EAN, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, EMI-Im, which have molecular masses of 108 and 391 amu, respectively. The beamlets are characterized with the time-of-flight technique to determine the impact velocity, stagnation pressure, and molecular kinetic energy of the projectiles, and to estimate their average diameters. The ranges of these parameters are 7–17 km/s, 40–190 GPa, 50–420 eV, and 10–14 nm. Under these conditions, we find that the molecular mass has a strong effect on sputtering: the sputtering yield for the heavier EMI-Im molecule is always higher than for EAN, with maximum values for Si, SiC, Ge, and GaAs of 4.3, 11.5, 10.9, and 9.4 atoms per EMI-Im molecule, and 1.1, 3.9, 3.3, and 2.9 in the case of EAN. More importantly, droplets of the same diameter (10 nm) and kinetic energy eject significantly different numbers of atoms, with average ratios between the EMI-Im and EAN droplets of 1.8, 1.5, 1.7, and 1.5 for Si, SiC, Ge, and GaAs. Molecular dynamics simulations reproduce the observed enhancement of the sputtering at increasing molecular mass.

Copyright 2015 American Association for Aerosol Research     

The Effect of the Electric Field on Lag Phase, β-Galactosidase Production and Plasmid Stability of a Recombinant Saccharomyces cerevisiae Strain Growing on Lactose

Ethanol and ??-galactosidase production from cheese whey may significantly contribute to minimise environmental problems while producing value from low-cost raw materials. In this work, the recombinant Saccharomyces cerevisiae NCYC869-A3/pVK1.1 flocculent strain expressing the lacA gene (coding for ??-galactosidase) of Aspergillus niger under ADHI promoter and terminator was used. This strain shows high ethanol and ??-galactosidase productivities when grown on lactose. Batch cultures were performed using SSlactose medium with 50?g?L^?1 lactose in a 2-L bioreactor under aerobic and microaerophilic conditions. Temperature was maintained at 30?°C and pH?4.0. In order to determine the effect of an electric field in the fermentation profile, titanium electrodes were placed inside the bioreactor and different electric field values (from 0.5 to 2?V?cm^?1) were applied. For all experiments, ??-galactosidase activity, biomass, protein, lactose, glucose, galactose and ethanol concentrations were measured. Finally, lag phase duration and specific growth rate were calculated. Significant changes in lag phase duration and biomass yield were found when using 2?V?cm^?1. Results show that the electric field enhances the early stages of fermentation kinetics, thus indicating that its application may improve industrial fermentations?? productivity. The increase in electric field intensity led to plasmid instability thus decreasing ??-galactosidase production.