Mathematical modelling and its use for design of feeding strategies for L‐Sorbose fermentation

Batch sorbitol to sorbose bioconversion by Acetobacter suboxydans using initial sorbitol concentration (S₀ = 100 g/L) yielded a productivity of 10.11 g/L‐h and 98.6% conversion in 10 h time. The batch kinetics was then used to develop an unstructured mathematical model. Model parameters were identified using a nonlinear regression technique assisted by a computer program which minimized the deviation between the model predictions and actual batch experimental data. F test indicated 99% confidence on the prediction of model using optimized parameters. The batch model was eventually extrapolated to identify nutrient feeding strategies to maintain constant noninhibitory sorbitol supply and eliminate substrate limitation for fed‐batch fermentation in order to improve the sorbose productivity. The adequacy of the fed‐batch model was established by excellent agreement between experimental data and model simulation (except towards the end of fermentation).     

Structural,electrical, and multiferroic properties of Aurivillius Bi<Subscript>6</Subscript>Fe<Subscript>2</Subscript>(Ti<Subscript>3-x</Subscript>V<Subscript>x</Subscript>)O<Subscript>18+δ</Subscript> thin films prepared by chemical solution deposition

Aurivillius type five-layered V-doped Bi₆Fe₂(Ti_3-xV_x)O_18+δ (x = 0.00, 0.03, 0.06, and 0.09) thin films were prepared on Pt(111)/Ti/SiO₂/Si(100) substrates by using a chemical solution deposition method. All the thin films were crystallized in Aurivillius structures, which have been confirmed by using X-ray diffraction and Raman spectroscopy studies. On comparing the thin films, the Bi₆Fe₂(Ti_2.94V_0.06)O_18+δ thin film showed the most enhanced electrical and multiferroic properties, with a leakage current density value about four orders of magnitude lower than that of the Bi₆Fe₂Ti₃O₁₈ thin film, for example. All of these thin films showed anti-ferromagnetic hysteresis loops at room temperature. The significant decrease in the concentration of oxygen vacancies and the formation of a stable structure caused by doping with the donor V⁵⁺-ion are related to the improved properties in the V-doped Bi₆Fe₂(Ti_3-xV_x)O_18+δ thin films.     

AHP-based procedure for optimization of microwave-assisted blackberry sugar osmotic process

Due to the limitations of single index analysis, the merits and demerits of microwave-assisted permeation process cannot be comprehensively evaluated. However, the analytical hierarchy process (AHP) was applied to optimize the conditions of microwave-assisted diffusion of sugar in blackberry. In this paper, the results of a single-factor experiment were compared with blackberry preserved after the treatment of microwave. An orthogonal rotation test procedure was designed to calculate the composite score of preserved blackberry fruit using AHP, and to determine the optimum processing conditions based on sugar osmosis characteristics. The results showed that the sugar content, vitamin C (VC) content, and color difference of treated blackberry increased with the increase of microwave power, the residence time, and the resulting sugar concentration. The composite grade points are listed to show that the optimum results were as follows: power level, the residence time, and the sugar concentration were, respectively, 210?W, 12?min, and 35%.     

Ta2O5/Nb2O5 and Y2O3 Co-doped Zirconias for Thermal Barrier Coatings

Zirconia doped with 3.2–4.2 mol% (6–8 wt%) yttria (3–4YSZ) is currently the material of choice for thermal barrier coating topcoats. The present study examines the ZrO₂-Y₂O₃-Ta₂O₅/Nb₂O₅ systems for potential alternative chemistries that would overcome the limitations of the 3–4YSZ. A rationale for choosing specific compositions based on the effect of defect chemistry on the thermal conductivity and phase stability in zirconia-based systems is presented. The results show that it is possible to produce stable (for up to 200 h at 1000°–1500°C), single (tetragonal) or dual (tetragonal + cubic) phase chemistries that have thermal conductivity that is as low (1.8–2.8W/m K) as the 3–4YSZ, a wide range of elastic moduli (150–232 GPa), and a similar mean coefficient of thermal expansion at 1000°C. The chemistries can be plasma sprayed without change in composition or deleterious effects to phase stability. Preliminary burner rig testing results on one of the compositions are also presented.     

Improvement in thermoelectric properties of an n-type bismuth telluride (Bi2Se0.3Te2.7) due to texture development and grain refinement during hot deformation

Hot deformation of an n-type bismuth telluride (nBT of composition Bi₂Se_0.3Te_2.7) results in a texture characteristic of the deformation mode. Extruded nBT has a fiber texture with ?112?0? directions aligned with the extrusion direction. Rolling of previously textured (extruded) and untextured (sintered powder compact) material results in a rolling texture with the basal plane parallel to the rolling plane, and the ?112?0? directions randomly oriented on the rolling plane. Results indicate an improvement in thermoelectric figure of merit at 300 K from 0.79 in the as-received extruded material to 0.93 in the rolled material.