The culture conditions of a multiphase fermentation involving morphologically complex mycelia were simulated in order to investigate the influence of mycelial morphology (Trichoderma harzianum) on castor oil and air dispersion. Measurements of oil drops and air bubbles were obtained using an image analysis system coupled to a mixing tank. Complex interactions of the phases involved could be clearly observed. The Sauter diameter and the size distributions of drops and bubbles were affected by the morphological type of biomass (pellets or dispersed mycelia) added to the system. Larger oil drop sizes were obtained with dispersed mycelia than with pellets, as a result of the high apparent viscosity of the broth, which caused a drop in the power drawn, reducing oil drop break-up. Unexpectedly, bubble sizes observed with dispersed mycelia were smaller than with pellets, a phenomenon which can be explained by the segregation occurring at high biomass concentrations with the dispersed mycelia. Very complex oil drops were produced, containing air bubbles and a high number of structures likely consisting of small water droplets. Bubble location was influenced by biomass morphology. The percentage (in volume) of oil-trapped bubbles increased (from 32 to 80%) as dispersed mycelia concentration increased. A practically constant (32%) percentage of oil-trapped bubbles was observed with pelleted morphology at all biomass concentrations. The results evidenced the high complexity of phases interactions and the importance of mycelial morphology in such processes.

AuFe electrodeposits onto a rotating disk electrode were examined to assess the composition and current efficiency behavior when citric acid, ascorbic acid, or a combination of both is present in the electrolyte. Nanowires were subsequently fabricated with pulsed current deposition to create compositionally, multilayered Au/FeAu nanowires. The FeAu layer of the nanowires was porous in a citrate electrolyte, but the porosity decreased with the addition of ascorbic acid in the electrolyte. Comparatively higher side reaction partial current densities ͑i sr ͒ in the citric acid electrolyte generated local alkaline conditions, inducing the chemical precipitation of Fe ions in the form of iron oxide nanoparticles inside the recess, which manifested as the regions of high porosity. Nonporous layers observed in the ascorbic acid bath, in combination with decreased i sr and increased current efficiency of the deposits, suggested that a similar mechanism of Fe precipitation inside the nanorecess is less likely.

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Image analysis was used to measure the effect of Tween 40 on the morphology of Trichoderma harzianum. The percentage of pellets was maximal (93%) with Tween at 0.2 ml l(-1), whereas the maximal proportion of dispersed mycelia (40%) was with Tween at 1.6 ml l(-1). The particle median diameter decreased from 2 to 0.5 mm as Tween concentration was increased and was inversely correlated to the biomass dry weight. Adding pre-determined aliquots of Tween 40 to the culture medium can be used to define the morphological characteristics of Trichoderma harzianum in submerged shake-flask culture.

The electrocatalytic activity of NiMo nanoparticles (NPs) fabricated by means of current pulses from a binary electrolyte was characterized using cyclic voltammetry. The pulse current density, jpulse, was varied in the range of 7 to 430 mA/cm2, whereas the pulse time, tpulse, was kept constant at two seconds. Mean NP size, Dmean, ranged within 27 and 38 nm at jpulse values between 15 and 140 mA/cm2; with Dmean increasing as jpulse was higher. NP dispersion (i. e., number of objects per unit area of substrate) was lower when jpulse values were also low (15 and 35 mA/cm2), which showed consistency with a promoted nuclei formation and prolonged NP growth at higher jpulse values. An improved catalytic performance for hydrogen evolution was determined upon increasing jpulse in the range of 7 to 70 mA/cm2 and remaining practically unvaried at higher jpulse values. The electrosynthesis of two distinct catalytic materials was indicated by electrochemical characterization of deposits; the material with greatest catalytic activity also showed high instability, causing a dramatic decay (~80%) in the activity after two consecutive cycles of operation. Ni and Mo content in electrodeposits were both sensitive to variations in jpulse.