Ultrasonic-vibration-assisted laser annealing of fluorine-doped tin oxide thin films for improving optical and electrical properties: Overlapping rate optimization

An ultrasonic-vibration-assisted laser annealing method was developed to enhance the performance of fluorine-doped tin oxide (FTO) thin films. The influences of ultrasonic vibration, laser scan line overlapping rate (L_OR) and laser spot overlapping rate (S_OR) on surface morphology, FTO layer thickness, RMS roughness, crystal structure and photoelectric properties of the FTO films were investigated. The results indicated that the presence of ultrasonic vibration during laser annealing could significantly enhance the film compactness, and using moderate L_OR and S_OR values resulted in significantly decreased FTO layer thicknesses and RMS roughnesses as well as slightly increased crystallite sizes, thus yielding significantly improved optical transmittance values and slightly enhanced electrical conductivity values. It was found that the optimal L_OR and S_OR values for ultrasonic-vibration-assisted laser annealing of the FTO films were 80% and 90%, respectively. The as-obtained film possessed the best overall photoelectric property with an average transmittance (400–800?nm) of 85.9%, a sheet resistance of 8.7?Ω/sq and a figure of merit of 2.51?×?10^–2 Ω^–1. This work may be of great significance in terms of performance optimization of transparent conducting oxide (TCO) thin films.     

Tribological behaviour of a 3Y-TZP/Ta ceramic-metal biocomposite against ultrahigh molecular weight polyethylene (UHMWPE)

This study aims to evaluate the tribological behaviour of 3Y-TZP/Ta (20 vol%) ceramic-metal composites and 3Y-TZP monolithic ceramic prepared by spark plasma sintering (SPS) against ultrahigh molecular weight polyethylene (UHMWPE). According to the results of pin (UHMWPE)-on-flat wear test under dry conditions, the UHMWPE – 3Y-TZP/Ta system exhibited lower volume loss and friction coefficient than the UHMWPE – monolithic ceramic combination due to the presence of an autolubricating layer that provides sufficient lubrication for reducing the friction. Owing to the lubrication of the liquid media, under wet conditions obtained using simulated body fluid (SBF), similar behaviour is observed in both cases. Additionally, the ceramic and biocomposite materials were subjected to a low temperature degradation (LTD) process (often referred to as “ageing”) to evaluate the changes in the tribological behaviour after this treatment. In this particular case, the wear properties of the UHMWPE-biocomposite system were found to be less influenced by ageing in contrast to the case of the UHMWPE-zirconia monolithic material. In addition to their exceptional mechanical performance, 3Y-TZP/Ta composites also showed high resistance to low temperature degradation and good tribological properties, making them promising candidates for biomedical applications, especially for orthopaedic implants.     

Research on the identification performance of UHF RFID system considering the correlation of cascaded channel

The identification rate of UHF RFID system was restricted by multipath propagation effects.The system identification performance was studied considering the correlation coefficient between forward and reverse channels.Based on the generalized Rician fading channel model,the analytical expression of identification rate was derived under independent,full correlation and correlation cases.Compared with the existing analysis,the proposed uniform calculation formula of identification rate was for any correlation coefficient and kinds of channel conditions.The numerical computation and Monte-carlo simulations show that the influences of different correlation coefficients,channel conditions,sensitivity and distance on the identification rate.     

Group sequential crossover trial designs with strong control of the familywise error rate

Crossover designs are an extremely useful tool to investigators, and group sequential methods have proven highly proficient at improving the efficiency of parallel group trials. Yet, group sequential methods and crossover designs have rarely been paired together. One possible explanation for this could be the absence of a formal proof of how to strongly control the familywise error rate in the case when multiple comparisons will be made. Here, we provide this proof, valid for any number of initial experimental treatments and any number of stages, when results are analyzed using a linear mixed model. We then establish formulae for the expected sample size and expected number of observations of such a trial, given any choice of stopping boundaries. Finally, utilizing the four-treatment, four-period TOMADO trial as an example, we demonstrate that group sequential methods in this setting could have reduced the trials expected number of observations under the global null hypothesis by over 33%.     

Validation of Models Predicting Nucleation Rates from Induction Times and Metastable Zone Widths

Three approaches for estimation of nucleation rates from induction time and metastable zone width (MSZW) were validated based on directly measured nucleation rates for paracetamol in ethanol. To quantitatively predict nucleation kinetics using Kubota's methods it is necessary to know the minimum detectable number concentration of nuclei. This was found by determination of light transmission of a series of diluted suspensions of newly nucleated crystals where the size had already been assessed by optical reflection measurement (ORM). The measured nucleation rates strongly depended on both temperature and supersaturation. The Nyvlt method predicted nucleation rates in this system reasonably well; however, it gave slightly low estimates for all temperatures. The methods of Kubota provided nucleation rates that were low by an order of magnitude.     

Crystal Structures and Phase Behavior of Sulfadiazine and a Method for the Preparation of Aggregates with Good Performance

The solvate and the solvent‐free form of sulfadiazine (SD) were investigated. SD was found to exist in one solvent‐free form and the N‐methylpyrrolidone (NMP) solvate form. The NMP solvate was shown to be a channel‐type compound. The intrinsic properties of the solvents were used to evaluate the effects of solubility on the phase transformation of SD and the NMP solvate. The SD phase could transform to the NMP solvate by NMP‐mediated phase transformation, which was governed by crystallization of the NMP solvate. The crystalline NMP solvate could transform to the solvent‐free solid state through solid‐solid transformation upon heating or water penetration‐mediated phase transformation. The rate of this water penetration‐mediated phase transformation of the NMP solvate to SD was unusually fast. It can be used to obtain SD aggregates of well‐defined shape and good powder properties.     

An approach to measure infill matric suction of irregular infilled rock joints under constant normal stiffness shearing

Rock joints infilled with sediments can strongly influence the strength of rock mass. As infilled joints often exist under unsaturated condition, this study investigated the influence of matric suction of infill on the overall joint shear strength. A novel technique that allows direct measurement of matric suction of infill using high capacity tensiometers (HCTs) during direct shear of infilled joints under constant normal stiffness (CNS) is described. The CNS apparatus was modified to accommodate the HCT and the procedure is explained in detail. Joint specimens were simulated by gypsum plaster using three-dimensional (3D) printed surface moulds, and filled with kaolin and sand mixture prepared at different water contents. Shear behaviours of both planar infilled joints and rough joints having joint roughness coefficients (JRCs) of 8–10 and 18–20 with the ratios of infill thickness to asperity height (t/a) equal to 0.5 were investigated. Matric suction shows predominantly unimodal behaviour during shearing of both planar and rough joints, which is closely associated with the variation of unloading rate and volumetric changes of the infill material. As expected, two-peak behaviour was observed for the rough joints and both peaks increased with the increase of infill matric suction. The results suggest that the contribution of matric suction of infill on the joint peak normalised shear stress is relatively independent of the joint roughness.