Phase Transformations in Calcium‐Substituted Lanthanum Ferrite

Phase equilibria in the La_1?xCa_xFeO_3?δ (LCF) system were assessed at temperatures below 1350°C in both simulated air and argon atmospheres using a combination of differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and high‐temperature X‐ray diffraction. The solubility limit of Ca in the perovskite structure was determined to be 38% A‐site substitution. A high‐temperature orthorhombic to rhombohedral transition was identified and the dependence on oxygen partial pressure and effect on thermal expansion were characterized. A partial, pseudobinary LaFeO₃–CaFeO_2.5 phase diagram is presented that is based on these analyses combined with data available in the open literature.     

Development and validation of chemistry agnostic flow battery cost performance model and application to nonaqueous electrolyte systems

A chemistry agnostic cost performance model is described for a nonaqueous flow battery. The model predicts flow battery performance by estimating the active reaction zone thickness at each electrode as a function of current density, state of charge, and flow rate using measured data for electrode kinetics, electrolyte conductivity, and electrode‐specific surface area. Validation of the model is conducted using a 4 kW stack data at various current densities and flow rates. This model is used to estimate the performance of a nonaqueous flow battery with electrode and electrolyte properties used from the literature. The optimized cost for this system is estimated for various power and energy levels using component costs provided by vendors. The model allows optimization of design parameters such as electrode thickness, area, flow path design, and operating parameters such as power density, flow rate, and operating SOC range for various application duty cycles. A parametric analysis is done to identify components and electrode/electrolyte properties with the highest impact on system cost for various application durations. A pathway to 100$ kW h^?1 for the storage system is identified. Copyright © 2016 John Wiley & Sons, Ltd.     

Short communication: Automatic washing of hooves can help control digital dermatitis in dairy cows

The objectives of this study were to develop and test a system for automatic washing of the hooves of dairy cows and to evaluate the effect of frequent automatic washing on the prevalence of digital dermatitis (DD). An automatic hoof washer was developed in an experimental dairy herd and tested in 6 commercial dairy herds in 2 experiments (1 and 2). In the experimental herd, automatic hoof washing resulted in cleaner hooves. In experiments 1 and 2, cows were washed after each milking on the left side only, leaving the right side unwashed as a within-cow control. In experiment 1, hooves were washed with a water and 0.4% soap solution. In experiment 2, hooves were washed with water only. In each experiment, DD was scored in a hoof-trimming chute approximately 60 d after the start of hoof washing. Data were analyzed using a generalized linear mixed model. The outcome was the DD status of each leg (DD positive or DD negative). Herd and cow within herd were included as random effects, and treatment (washing or control) was included as a fixed effect. The statistical analyses showed that the odds ratio of having DD was 1.48 in the control leg compared with the washed leg in experiment 1. In experiment 2, the odds ratio of having DD was 1.27 in the control leg compared with the washed leg. We concluded that automatic washing of hooves with water and soap can help decrease the prevalence of DD in commercial dairy herds.     

Optical raster-scanning displays based on surface-micromachinedpolysilicon mirrors

We demonstrate high-resolution, raster-scanning display systems based on pairs of orthogonally scanning, surface-micromachined mirrors. The first mirror of the raster-scanning pair determines the line-scan rate of the display and is driven at its resonant frequency which is on the order of 4.7 kHz. The second mirror, driven at a frequency below its resonance and scanning orthogonally to the first mirror, determines the image refresh rate. Both mirrors have a maximum optical scanning angle of 15°. Single-chip and two-chip scanners are demonstrated. The resolution of the single-chip display, based on average pixel size, is 102×119 pixels. The curvature of the mirror surfaces are characterized and optically compensated to achieve this resolution     

Integrin and chemokine receptor gene expression in implant-adherent cells during early osseointegration

The mechanisms of early cellular recruitment and interaction to titanium implants are not well understood. The aim of this study was to investigate the expression of pro-inflammatory cytokines, chemokines and adhesion markers during the first 24 h of implantation. Anodically oxidized and machined titanium implants were inserted in rat tibia. After 3, 12, and 24 h the implants were unscrewed and analyzed with quantitative polymerase chain reaction. Immunohistochemistry and scanning electron microscopy revealed different cell types, morphology and adhesion at the two implant surfaces. A greater amount of cells, as indicated by higher expression of small subunit ribosomal RNA (18S), was detected on the oxidized surface. Higher expression of CXC chemokine receptor-4 (at 12 h) and integrins, αv (at 12 h), β1 (at 24 h) and β2 (at 12 and 24 h) was detected at the oxidized surfaces. Significantly higher tumor necrosis factor-α (at 3 h) and interleukin-1β (at 24 h) expression was demonstrated for the machined surface. It is concluded that material surface properties rapidly modulate the expression of receptors important for the recruitment and adhesion of cells which are crucial for the inflammatory and regenerative processes at implant surfaces in vivo.     

An electrolyte CPA equation of state for mixed solvent electrolytes

Despite great efforts over the past decades, thermodynamic modeling of electrolytes in mixed solvents is still a challenge today. The existing modeling frameworks based on activity coefficient models are data‐driven and require expert knowledge to be parameterized. It has been suggested that the predictive capabilities could be improved through the development of an electrolyte equation of state. In this work, the Cubic Plus Association (CPA) Equation of State is extended to handle mixtures containing electrolytes by including the electrostatic contributions from the Debye–Hückel and Born terms using a self‐consistent model for the static permittivity. A simple scheme for parameterization of salts with a limited number of parameters is proposed and model parameters for a range of salts are determined from experimental data of activity and osmotic coefficients as well as freezing point depression. Finally, the model is applied to predict VLE, LLE, and SLE in aqueous salt mixtures as well as in mixed solvents. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2933–2950, 2015     

Dependence of shear and concentration on fouling in a membrane bioreactor with rotating membrane discs

Rotating ceramic membrane discs were fouled with lab‐scale membrane bioreactors (MBR) sludge. Sludge filtrations were performed at varying rotation speeds and in different concentric rings of the membranes on different sludge concentrations. Data showed that the back transport expressed by limiting flux increased with rotation speed and distance from membrane center as an effect of shear. Further, the limiting flux decreased with increasing sludge concentration. A model was developed to link the sludge concentration and shear stress to the limiting flux. The model was able to simulate the effect of shear stress and sludge concentration on the limiting flux. The model was developed by calculating the shear rate at laminar flow regime at different rotation speeds and radii on the membrane. Furthermore, through the shear rate and shear stress, the non‐Newtonian behavior of MBR sludge was addressed. © 2013 American Institute of Chemical Engineers AIChE J 60: 706–715, 2014     

AFM study of glucagon fibrillation via oligomeric structures resulting in interwoven fibrils

Glucagon is a 29-residue amphiphatic hormone involved in the regulation of blood glucose levels in conjunction with insulin. In concentrated aqueous solutions, glucagon spontaneously aggregates to form amyloid fibrils, destroying its biological activity. In this study we utilize the atomic force microscope (AFM) to elucidate the fibrillation mechanism of glucagon at the nanoscale under acidic conditions (pH?2.0) by visualizing the nanostructures of fibrils formed at different stages of the incubation. Hollow disc-shaped oligomers form at an early stage in the process and subsequently rearrange to more solid oligomers. These oligomers co-exist with, and most likely act as precursors for, protofibrils, which subsequently associate to form at least three different classes of higher-order fibrils of different heights. A repeat unit of around 50?nm along the main fibril axis suggests a helical arrangement of interwoven protofibrils. The diversity of oligomeric and fibrillar arrangements formed at pH?2.0 complements previous spectroscopic analyses that revealed that fibrils formed under different conditions can differ substantially in stability and secondary structure.     

Aerodynamic optimization of wind turbine rotors using a blade element momentum method with corrections for wake rotation and expansion

The blade element momentum (BEM) method is widely used for calculating the quasi‐steady aerodynamics of horizontal axis wind turbines. Recently, the BEM method has been expanded to include corrections for wake expansion and the pressure due to wake rotation (), and more accurate solutions can now be obtained in the blade root and tip sections. It is expected that this will lead to small changes in optimum blade designs. In this work, has been implemented, and the spanwise load distribution has been optimized to find the highest possible power production. For comparison, optimizations have been carried out using BEM as well. Validation of shows good agreement with the flow calculated using an advanced actuator disk method. The maximum power was found at a tip speed ratio of 7 using , and this is lower than the optimum tip speed ratio of 8 found for BEM. The difference is primarily caused by the positive effect of wake rotation, which locally causes the efficiency to exceed the Betz limit. Wake expansion has a negative effect, which is most important at high tip speed ratios. It was further found that by using , it is possible to obtain a 5% reduction in flap bending moment when compared with BEM. In short, allows fast aerodynamic calculations and optimizations with a much higher degree of accuracy than the traditional BEM model. Copyright © 2011 John Wiley & Sons, Ltd.