Dynamic visualization of eutectic reaction between boron carbide and stainless steel

To investigate the eutectic reaction process of control-rod materials in a boiling water reactor (BWR), fundamental tests using boron carbide (B₄C) powder inserted between stainless steel (SS) plates were performed and dynamically visualized. The eutectic reaction process near the contact area of the two materials and the behavior of molten material and B₄C powder were visualized in real time. The temperature, reaction area, and maximum reaction-layer thickness were obtained. The average temperature range of the test was 1455–1481 K. Through dynamic visualization, some important and previously undiscovered phenomena were observed. The solid part of the SS plate and the strong surface tension of the melt retained the melt inside the specimen, preventing it from flowing out from the surface; the melt then invaded the B₄C powder region during the reaction. Diffusion of the B₄C powder and migration of the nonreacted B₄C powder from the B₄C powder region through the retained melt to the SS region were observed. This migration accelerated the local reaction growth rate. The time-resolved observation of these dynamic phenomena offers significant insights to the improvement of numerical calculation codes for severe accident analyses of BWRs, including the Fukushima Daiichi nuclear reactors.     

Emerging Anti-Inflammatory Pharmacotherapy and Cell-Based Therapy for Lymphedema

Secondary lymphedema is a common complication of lymph node dissection or radiation therapy for cancer treatment. Conventional therapies such as compression sleeve therapy, complete decongestive physiotherapy, and surgical therapies decrease edema; however, they are not curative because they cannot modulate the pathophysiology of lymphedema. Recent advances reveal that the activation and accumulation of CD4+ T cells are key in the development of lymphedema. Based on this pathophysiology, the efficacy of pharmacotherapy (tacrolimus, anti-IL-4/IL-13 antibody, or fingolimod) and cell-based therapy for lymphedema has been demonstrated in animal models and pilot studies. In addition, mesenchymal stem/stromal cells (MSCs) have attracted attention as candidates for cell-based lymphedema therapy because they improve symptoms and decrease edema volume in the long term with no serious adverse effects in pilot studies. Furthermore, MSC transplantation promotes functional lymphatic regeneration and improves the microenvironment in animal models. In this review, we focus on inflammatory cells involved in the pathogenesis of lymphedema and discuss the efficacy and challenges of pharmacotherapy and cell-based therapies for lymphedema.     

Optimal energy consuming planning for a home-based microgrid with mobility constraint of electric vehicles and tractors

This research deals with the energy management problem to minimize the cost of non-renewable energy for a small-scale microgrid with electric vehicles(EV)and el...     

Cathode having high rate performance for a secondary Li-ion cell surface-modified by aluminum oxide nanoparticles

In order to enhance the electrochemical properties, the spinel LiMn₂O₄ electrode surface was modified with amorphous Al₂O₃ nanoparticle as heterogeneous phase. LiMn₂O₄ was in preparation based on a conventional solid-state reaction. The LiMn₂O₄ procedure was soaked in aluminum tri 2-propoxide solution. The LiMn₂O₄ whose surface was modified by aluminum oxide was obtained through the heat treatment at 400 °C for 4 h. The Al₂O₃-modified LiMn₂O₄ electrode exhibits a capacity higher than that of the unmodified LiMn₂O₄ electrode. On the other hand, no variation was shown with open circuit potential and apparent chemical diffusion coefficient of Li ion for LiMn₂O₄ before and after the surface modification. The charge-transfer resistance of Al₂O₃-modified LiMn₂O₄ decreased significantly in comparison with the unmodified LiMn₂O₄. The improved charge-transfer kinetics was largely attributed to Al₂O₃ which plays an important role of increasing the chemical potential at the electrode/electrolyte interface.     

Dynamic motion of a conductive particle in viscous fluid under DCelectric field

When plastic waste is liquefied for recycling, the impurities present could influence the quality of the reprocessed products. In order to explore the possible method for removing solid impurities using electrostatic forces, the motion of spherical conductive particles under a uniform electric field has been carefully investigated. In this paper, a solid impurity and liquefied plastics are simulated by a conductive spherical particle and viscous insulating liquid, silicone oil, respectively. Experimental results indicate that the particle undergoes repeated motion between the parallel electrodes. The motion of the particle can be divided into four modes: settling on the lower electrode, moving upward, settling on the upper electrode, and moving downward. The higher the applied voltage, the faster the average particle velocity and the shorter the resting time of the particle. The particle accelerates after leaving the electrode and decelerates before reaching the other electrode. This deceleration could be explained by the viscous effect of the liquid layer between the particle and the electrode. The settling mode could be explained by the fact that there is a liquid flow induced by the particle motion and it pushes the particle against the electrode until the flow decreases. It is, therefore, suggested that the hydrodynamic effect is dominant in our case, as well as the electrostatic force     

Influencing factors on nugget formation during multipoint welding by single-side resistance spot welding

ABSTRACT

Recently, weight reduction and improvement of crashworthiness of auto bodies have become important issues. At the same time, stiffness of auto bodies is also needed to ensure a smooth ride. Using hollow parts, such as bended pipes and hydroformed parts, is one of the solutions to the demand for both rigidity and light weight.

To weld hollow parts and sheet panels together, welding methods which allow us to access from one side are required. Single-side resistance spot welding (single-side RSW) process is one of those, and has recently been attracting attention.

However, because of the long current path and small electrode force, it is difficult to concentrate the electric current in the welding spot compared with conventional direct resistance spot welding (direct RSW). Furthermore, in multipoint welding, shunt current will occur easily, and the nugget formation will be inhibited.

To obtain a guideline for making sound nuggets, influencing factors for shunt current were investigated. In addition, a numerical study was carried out to discuss the difference between direct RSW and single-side RSW.

According to the CAE analysis, the shunt current of single-side RSW will be higher rate than direct RSW. The rate of shunt current was influenced by the electrical resistance of its current path. For this reason, with shorter distance between welding points, or with lower electrical resistance of material, it is difficult to get large nuggets. By enhancing the electrical resistance of shunt current path, shunt current could be reduced and a larger nugget would be obtained.     

Inhibition of Calcineurin and Glycogen Synthase Kinase-3β by Ricinoleic Acid Derived from Castor Oil

Ricinoleic acid (RA) is the main fatty acid component of castor oil and was found to inhibit Ca²⁺-signal transduction pathway-mediated cell cycle regulation in a yeast-based drug screening assay. RA is expected to have antidiabetic, antiallergy, and/or anticancer properties but its target molecule is unknown. To identify a novel pharmacological effect of RA, we investigated its target molecule in the Ca²⁺-signal transduction pathway. RA inhibition of calcineurin (CN) was examined in a yeast-based CN inhibitor screening assay using the rsp5^A401E mutant and in a phosphatase assay using recombinant human CN. RA showed growth-restoration activity at 5 μg/spot in the CN inhibitor screening assay with the rsp5^A401E yeast strain. Furthermore, it directly inhibited CN without immunophilins at K_i = 33.7 μM in a substrate-competitive manner. The effects of RA on CN in mammalian cells were further evaluated by measuring β-hexosaminidase (β-HEX) release in RBL-2H3 cells. RA at 50 μM suppressed the release of β-HEX from RBL-2H3 cells. Moreover, this compound was found to inhibit glycogen synthase kinase-3β (GSK-3β), as determined by a kinase assay using recombinant human GSK-3β. RA inhibited GSK-3β at K_i = 1.43 μM in a peptide substrate-competitive manner. The inhibition of GSK-3β by this molecule was further assessed in mammalian cells by measuring the inhibition of glucose production in H4IIE rat hepatoma cells. RA at 25 μM suppressed glucose production in these cells. These findings indicate that RA and/or castor oil could be a useful functional fatty acid to treat allergy or type 2 diabetes.     

Robust Voice Activity Detection Based on Concept of Modulation Transfer Function in Noisy Reverberant Environments

Voice activity detection (VAD) is used to detect speech and non-speech periods from observed speech signals. It is an important front-end technique for many speech technology applications. Many VAD methods have been proposed. However most of them have been applied under clean or noisy conditions. Only a few methods have been proposed for reverberant conditions, particularly under noisy reverberant conditions. We therefore need to understand the ill effects of noise and reverberation on speech to design an accurate and robust method of VAD under noisy reverberant conditions. The ill effects of noise and reverberation for speech can be regarded as the modulation transfer function (MTF) under noisy and reverberant conditions. Therefore, our study is based on the MTF concept to reduce the ill effects of noise and reverberation on speech, and propose a robust VAD method that we obtained in this study. Noise reduction and dereverberation were first applied to the temporal power envelope of the speech signal to restore the temporal power envelope with this method. Then, power thresholding as a VAD decision was designed based on the restored temporal power envelope. A method of estimating the signal to noise ratio (SNR) was proposed to accurately estimate the SNR in the noise reduction stage. Experiments under both artificial and realistic noisy reverberant conditions were carried out to evaluate the performance of the proposed method of VAD and it was compared with conventional VAD methods. The results revealed that the proposed method significantly outperformed the conventional methods under artificial and realistic noisy reverberant conditions.     

Combustion synthesis of α-Si3N4 assisted by molten salt additives

Combustion synthesis (CS) of silicon nitride (Si₃N₄), assisted by molten salt additives under high N₂ pressure, is reported. The effect of salt additives (NaCl, MgCl₂, and MgCl₂?6H₂O) on the reaction temperature and the final α-Si₃N₄ content is studied. The maximum reaction temperature (T_max) decreased with an increase in the amount of the salt additives. NaCl is found to be the most suitable as it results in 57.8% α-Si₃N₄ at 30 mass% concentration. MgCl₂ is strongly hygroscopic, and MgCl₂?6H₂O decomposes at very low temperature. Therefore, they absorb heat at low temperatures, which makes it difficult to reach the ignition temperature, thereby hindering the reaction propagation. Si₃N₄ is necessary as a diluent for creating pores in the raw materials to allow effective penetration and contact of N₂ gas with the Si particles.     

Low-voltage charge pump circuit with double boost technique

In recent years, interest in IoT (Internet of Things) has been increasing, and energy harvesting has attracted attention. However, the power and voltage that can be harvested are very small. Therefore, a power supply circuit is required to solve this problem. In this paper, we have realized a boost circuit that does not require a coil with the aim of integrating all the circuits required for sensing on one chip.