Fabrication of particle-free thin films by laser ablation combined with an electron beam

Particle-free silicon and nickel thin films were successfully fabricated by laser-ablating a melted section of their target surface, which gives a high evaporation pressure at the melting point. The influence of direct evaporation from a melted target was reduced negligibly by melting the target only locally with a focused electron beam (e-beam) and increasing the laser frequency. The silicon films fabricated by the present method, pulse laser deposition of a partially molten target, were able to firmly adhere to the substrates and withstood steel needle scratching, unlike e-beam-evaporated films.     

A rate-dependent cohesive model for simulating dynamic crack propagation in brittle materials

Numerical investigations are conducted to simulate high-speed crack propagation in pre-strained PMMA plates. In the simulations, the dynamic material separation is explicitly modeled by cohesive elements incorporating an initially rigid, linear-decaying cohesive law. Initial attempts using a rate-independent cohesive law failed to reproduce available experimental results as numerical crack velocities consistently overestimate experimental observations. As proof of concept, a phenomenological rate-dependent cohesive law, which bases itself on the physics of microcracking, is introduced to modulate the cohesive law with the macroscopic crack velocity. We then generalize this phenomenological approach by establishing a rate-dependent cohesive law, which relates the traction to the effective displacement and rate of change of effective displacement. It is shown that this new model produces numerical results in good agreement with experimental data. The analysis demonstrates that the simulation of high-speed crack propagation in brittle structures necessitates the use of rate-dependent cohesive models, which account for the complicated rate-process of dynamic fracture at the propagating crack tip.     

Comparisons of optimal release policies for software systems

In a software product management, it is an important problem to determine the optimal release timing which minimizes the total expected cost incurred in both testing and operation phases. In this paper, we compare the performance between two kinds of software release methods, which are referred to as the T-policy and the N-policy. Based on the existing software reliability growth models, we formulate the expected cost functions and derive analytically the optimal policies under these control methods. Also, we derive a criterion for which control methods should be adopted. Finally, in numerical examples, we calculate the optimal release policies for several cost parameters.     

Parallel processing circuit of line image using neuristor

A simultaneous detecting circuit system of centers and lengths of some lines in one dimension is presented applying an electronic circuit model of the nervous axon with respect to signal transmission. This model consists of series of one basic section, and has functions of Neuristor. The circuit system has a paralell processing function. It is constructed by three layers. In the first layer each visual signal of lines is changed to electric pulse signal. In the second layer edges of each line are detected, and in the third layer these detected signals are converted into voltages which correspond to lengths of the lines. These functions were confirmed experimentally using its hardware.     

Fabrication and characterization of potassium-sodium niobate piezoelectric ceramics by spark-plasma-sintering method

High density (Na_1−xK_x)NbO₃ (x = 0.5, 0.6, and 0.7) ceramics were successfully prepared by spark-plasma-sintering (SPS) method. The dielectric and piezoelectric properties of the SPS samples were investigated and compared to that of hot-pressed samples. It is found that, the SPS-sintered (Na_1−xK_x)NbO₃ samples show higher room temperature dielectric constant, higher coercive fields, lower remnant polarizations and lower electromechanical coefficients than that of the hot-pressed (Na_1−xK_x)NbO₃ samples. The dielectric and piezoelectric property differences between the SPS-sintered and hot-pressed samples have been attributed to grain size effects.     

Electrochemical behaviors of uranium and plutonium at simultaneous recoveries into liquid cadmium cathodes

Experiments were conducted on simultaneous recovery of uranium and plutonium electrochemically into laboratory scale liquid cadmium cathodes (LCCs) at different U/Pu ratios in the salt phase, and the influence of the salt composition on the recovered amounts of uranium and plutonium, the morphologies of uranium and plutonium in the LCC, and the behavior of americium, which is present as a decay product of plutonium-241, were examined. As a result, it was shown that there is a threshold in the U/Pu ratio in the salt phase between 1/4.3 and 1/1.73 for the successful simultaneous recovery of uranium and plutonium up to 10 wt% in the LCC at high current efficiencies. In the LCC, uranium and plutonium existed in the forms of intermetallic compounds, (U, Pu)Cd₆ and (U, Pu)Cd₁₁, and also pure uranium metal. It was also revealed that americium associates with plutonium according to the separation factor during the LCC operation.     

Identification of charge‐transfer transition between Gd3+ to O2− in gadolinium‐containing oxide phosphors in VUV region

Abstract— The broad bands at around 155 nm for GdAl₃(BO₃)₄:Eu, at 184 nm for Ca₄GdO(BO₃)₃:Eu, at 183 nm for Gd₂SiO₅:Eu, and at 170 nm for GdAlO₃:Eu were observed. These bands were assigned to the charge‐transfer (CT) transition of Gd³⁺‐O^2?. In the excitation spectrum of (Gd,Y)BO₃:Eu, a broadened excitation band was observed in VUV region. It could be considered that this band was composed of two bands at about 160 and 166 nm. The preceding band was assigned to the BO₃ group absorption. The later one at about 166 nm could be assigned to the CT transition of Gd³⁺‐O^2?, according to the result of GdAl₃(BO₃)₄:Eu, Ca₄GdO(BO₃)₃:Eu, Gd₂SiO₅:Eu, and GdAlO₃:Eu. The excitation spectra overlapped between the CT transition of Gd³⁺‐O^2? and BO₃ groups absorption. It caused the emission of Eu³⁺ to take place effectively in the trivalent europium‐doped (Gd,Y)BO₃ host lattice under 147‐nm excitation.     

Macrophage Activation Markers Predict Liver-Related Complications in Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) has a wide variation in clinical presentation and course. There is no significant correlation between these symptoms and the disease stage, although patients with more advanced stages generally have more symptoms. It is important to develop biomarkers in order to identify patients with an increased risk of complications and end-stage liver disease. This study investigated surrogate markers for risk estimation of PBC-related complications, including a study population of 77 patients with PBC who underwent liver biopsy and were measured for serum levels of macrophage activation markers, soluble CD163 (sCD163), soluble mannose receptor (sMR), and zonulin. Patients with PBC were divided into symptomatic (Group S, n = 20) and asymptomatic (Group A, n = 57) groups. The correlations of histological stages based on both Scheuer and Nakanuma classifications with the three serum markers were investigated. The Nakanuma classification involves grading for liver fibrosis and bile duct loss. The three biomarkers were assessed for their diagnostic ability to identify patients with PBC having high risk of developing complications. The predictive factors of these complications were examined as well. Group S had significantly higher serum sMR (p = 0.011) and sCD163 (p = 0.048) levels versus Group A. A composite index of sMR and sCD163 measurements had significantly better prediction performance than sCD163 alone (p = 0.012), although not when compared to sMR alone (p = 0.129). Serum sMR was an independent factor for developing complications on both univariate (Odds ratio (OR) = 30.20, 95% confidence interval (95% CI): 3.410–267.0, p = 0.00220), and multivariate (OR = 33.70, 95% CI: 3.6600–311.0, p = 0.0019) analyses. Patients with PBC having sMR of ≥56.6 had a higher incidence of clinical complications versus those with a sMR of <56.6. Serum sMR predicts the development of complications in patients with PBC. sMR plus sCD163 showed better predictive power than either marker alone, although the addition of sCD163 did not improve the predictive power of sMR. Future prospective studies are required in order to validate the findings of the present study.     

Pressure Rise and Propagation Phenomena Due to Fault Arc in Container with Opened Pipe

This paper describes experimental and analytic studies on pressure rise and propagation phenomena due to high current arcs in a container with opened pipes. The shape of the experimental container was chosen taking into account underground common ducts. First, arcs were ignited in the container with varying diameter D and length L of the opened pipes and at arc currents of 4 kA to 12.5 kA and an arc duration of 0.1 s. Based on measured waveforms, the maximum pressure rise and the pressure oscillation frequency were obtained. It was found that there is a tendency for to increase with decreasing D and increasing L, and that D has a much greater impact on . In addition, the tendencies of with changing D and L can be approximately explained by Helmholtz resonance. Second, a CFD model for the container with opened pipe was developed based on the experimental results, and simulations were performed. The simulation results were found to correspond to the experimental pressure rise.     

Tensile Properties and Fracture Behavior of Different Carbon Nanotube-Grafted Polyacrylonitrile-Based Carbon Fibers

The tensile properties and fracture behavior of different carbon nanotube (CNT)-grafted polyacrylonitrile-based (T1000GB) single carbon fibers were investigated. Grafting of CNTs was achieved via chemical vapor deposition (CVD). When Fe(C₅H₅)₂ (also applied via CVD) was used as the catalyst, the tensile strength and Weibull modulus of the carbon fibers were improved, possibly due to the growth of dense CNT networks on the carbon fibers, which may have led to a reduction in the number of strength-limiting defects. Separately, at lower concentrations of an Fe(NO₃)₃·9H₂O catalyst in ethanol, which was applied via dipping, the tensile strength of CNT-grafted fibers was nearly identical to that of the as-received fibers, although the Weibull modulus was higher. For higher concentrations of the Fe(NO₃)₃·9H₂O catalyst, however, the tensile strength and the Weibull modulus were lower than those for the as-received material. Although the density of the CNT network increased with the concentration of the Fe(NO₃)₃·9H₂O catalyst in the ethanol solution, heating of the ethanolic Fe(NO₃)₃·9H₂O catalyst solution generated nitric acid (HNO₃) due to decomposition, which damaged the fiber surfaces, resulting in an increase in the number of flaws and consequently a reduction in the tensile strength. Therefore, the tensile strength and Weibull modulus of CNT-grafted carbon fibers vary due to the combination of these effects and as a function of the catalyst concentration.