Preconditioned iterative solver on the coarsest level of a multi-grid method for high frequency time harmonic electromagnetic field analyses

A multi-grid method is one of the most powerful linear solvers for finite element electromagnetic field analysis. However, as the discretized model has recently been enlarged, a solution process for a linear system arising on the coarsest level tends to be problematic in a complete multi-grid solution process. Whereas a linear system on the coarsest level is generally solved by a direct solver, we solve it here by means of an iterative solver to reduce the memory requirements. Since a conventional preconditioning technique is not effective for such a linear system, we introduce preconditioning techniques based on Arnold, Falk, and Winther’s and on Hiptmair’s smoothers. Numerical tests show that the newly installed preconditioning technique greatly improves the convergence rate.     

Research on machine recognition of handprinted characters

Machine recognition of handprinted Chinese characters has recently become very active in Japan. Both from the practical and the academic point of view, very encouraging results are reported. The work is described systematically and analyzed in terms of so-called feature matching, which is likely to be the mainstream of the research and development of machine recognition of handprinted Chinese characters. A database, ETL8 (881 Kanji, 71 hirakana, and 160 variations for each category), is explained, on which many experiments were performed. Recognition rates reported using this database can be compared, and so somewhat qualitative evaluation of these methods is described. Based on the comparative study, the merits and demerits of both feature and structural matching are discussed and some future directions are mentioned.     

Molecular pharmacology of voltage-dependent calcium channels

Voltage-dependent Ca2+ channels serve as the only link to transduce membrane depolarization into cellular Ca(2+)-dependent reactions. A wide variety of chemical substances that have the ability to modulate Ca2+ channels have been demonstrated both for their clinic utility and for importance in elucidating the molecular basis of various biological responses. Recently, introduction of molecular biology to pharmacology has brought a great deal of information about the molecular basis of drug action in Ca2+ channels. In this review, we attempt to overview recent progress in understanding the interactions between Ca2+ channels and their blockers, namely Ca2+ antagonists, from a molecular and structural point of view.     

Focused Design of Novel Cyclic Peptides Endowed with GABARAP-Inhibiting Activity

(1) Background: Disfunctions in autophagy machinery have been identified in various conditions, including neurodegenerative diseases, cancer, and inflammation. Among mammalian autophagy proteins, the Atg8 family member GABARAP has been shown to be greatly involved in the autophagy process of prostate cancer cells, supporting the idea that GABARAP inhibitors could be valuable tools to fight the progression of tumors. (2) Methods: In this paper, starting from the X-ray crystal structure of GABARAP in a complex with an AnkirinB-LIR domain, we identify two new peptides by applying in silico drug design techniques. The two ligands are synthesized, biophysically assayed, and biologically evaluated to ascertain their potential anticancer profile. (3) Results: Two cyclic peptides (WC8 and WC10) displayed promising biological activity, high conformational stability (due to the presence of disulfide bridges), and K_d values in the low micromolar range. The anticancer assays, performed on PC-3 cells, proved that both peptides exhibit antiproliferative effects comparable to those of peptide K1, a known GABARAP inhibitor. (4) Conclusions: WC8 and WC10 can be considered new GABARAP inhibitors to be employed as pharmacological tools or even templates for the rational design of new small molecules.     

Microstructure and Thermoelectric Properties of Dense YB<Subscript>22</Subscript>C<Subscript>2</Subscript>N Samples Fabricated Through Spark Plasma Sintering

Dense samples of the higher boride YB₂₂C₂N have been fabricated through the spark plasma sintering (SPS) method with different sintering aids. YB₂₂C₂N is a representative of a series of newly discovered rare-earth borocarbonitrides, which may be the long-awaited n-type counterpart of boron carbide, “B₄C.” The effect of Si, SiC, Al, and TiC additions on the sintering process of YB₂₂C₂N has been studied. The best sintered bodies with densities higher than 90% of theoretical density were obtained by means of SPS at 1700°C. We show that the additive choice and pressure have an effect on grain size and density. An investigation of the effect of atmosphere on the sintering behavior has also been carried out. It was found that sinterability is enhanced under nitrogen atmosphere. Thermoelectric properties of the materials sintered with additives have been evaluated, and we discuss their dependences on the fabrication process route.     

Class DE current-source parallel resonant inverter

This paper introduces a Class DE current-source parallel resonant inverter, along with its design procedure and experimental results. This circuit offers several desirable features. First, the proposed circuit lacks harmonic components of input current over the voltage-source inverters. Second, the source pin of the MOSFET is directly connected to the ground, so that it is not necessary to use a complicated gate-drive circuit. Third, by maintaining zero-current switching, power loss by the parasitic inductor at turn-off decreases. The measured efficiency is over 90% at the output power of 3.5 W and the operating frequency of 0.5 MHz     

In situ HREM study on the structural instability of isolated nanometre-sized alloy particles in the Sn-Bi system

The structural instability of isolated nm-sized alloy particles has been investigated by in situ transmission electron microscopy, using particles in the Sn-Bi system. In a pure tin (Sn) particle, no structural fluctuation was induced under electron-beam irradiation. In a tin-rich solid solution particle, an orientational fluctuation took place at a rate of approximately once per 1-3 s. In a high concentration alloy particle with a two-phase microstructure, a structural fluctuation occurred at a rate of a few hertz. Namely, the fluctuation became more frequent with increasing bismuth (Bi) concentration, no matter whether it consists of a single phase or multiple phases. A good parallelism can be found between this fluctuation enhancement with bismuth concentration and the fact that the free-energy difference between a solid particle and the corresponding liquid one decreases continuously with bismuth concentration and approaches a value close to zero at the eutectic composition. These results lead to a view that a nm-sized solid particle exhibits a structural instability under electron-beam irradiation when the free-energy difference between a solid particle and the corresponding liquid one is reduced to a value close to zero.     

Analysis of class D inverter with irregular driving patterns

This paper presents an analysis of Class D inverter when irregular driving patterns are given to the gate drive of the switch devices. The analysis has been carried out with focusing on the waveforms, harmonics, low-frequency components, output power, and equivalent dc resistance, which are numerically analyzed and discussed. Class D inverters with six different Q factors from 0.1 to 20 are analyzed about 2/sup 16/ driving patterns for each Q. Superior four models of the six inverters are built and tested in circuit experiments. The calculated waveforms are compared to the experimental results. Both of them are agreed well in time domain and frequency domain. Analytical results show a possibility of a novel control method with irregular driving patterns. In spite of discontinuous control, the output power or voltage can be strictly changed as if continuous using the selected driving patterns in some ranges.     

Lithium Ion Secondary Cell Prepared by a Printing Procedure,and Its Application to All-Solid-State Inorganic Lithium Ion Cells

We have developed a straightforward printing method for preparation of a lithium secondary cell. LiCo_1/3Ni_1/3Mn_1/3O₂ and Li₄Ti₅O₁₂ viscous printable pastes were used for the cathode and anode, respectively. Electrochemical measurement was used to characterize the capacitance of each cell, and field-emission scanning electron microscopy and particle size measurements were used to characterize particle size and morphology. These film electrodes functioned stably both in a standard liquid electrolyte and in an Li₂SiO₃ solid electrolyte, although the capacitance of the all-solid-state cell was significantly lower than that of the cell containing liquid electrolyte. When liquid electrolyte was used, the capacity decreased by 36% after 50 cycles. However, the capacity of 0.2 mA h/g remained almost the same even after 50 charge–discharge cycles, demonstrating the stability and strength of the all-solid-state lithium ion cell. It was also found that the cell resistance mostly arose from the electrode/electrolyte interface and not from the bulk electrolyte. Addition of a sol–gel to the solid electrolyte printable paste improved cell performance.     

Two-dimensional GaAs photonic switch array with direct gain andhigh contrast

The fabrication and design of a 4×4 surface-normal reflection photonic switch array, with an operating principle based on the change of the gain coefficient in GaAs, is described. A 3-μm-thick GaAs active layer and carrier confinement layers are sandwiched between a semiconductor multilayer reflector and an antireflection window. The beryllium ion implantation technique is used to make a narrow current path to reduce the operation current. Each photonic switch independently realizes direct amplification and absorption of the optical signal. It features an optical gain of 4 dB and a contrast of 9.6 dB, for an applied voltage of 2.2 V. The array has a simple planar structure