An extended Kolmogorov-Avrami-Ishibashi (EKAI) model to simulate dynamic characteristics of polycrystalline-ferroelectric-gate field-effect transistors

An extended Kolmogorov-Avrami-Ishibashi (EKAI) model is proposed, which represents dynamic characteristics in polycrystalline ferroelectric films consisting of grains under time-dependent electric fields. The original Kolmogorov-Avrami-Ishibashi (KAI) model described time-varying polarization reversal in a single-crystal film under a constant electric field. The field and the polarization were directed along the film normal. The polarization reversal dynamics were represented by a time-evolution function, c(t), regarding the volume fractions of the downward- and upward-polarization domains under a constant electric field. In the EKAI model, a grain in a polycrystalline ferroelectric film is indexed by l with an angle theta which is the angle between the spontaneous polarization Ps and the film normal. The EKAI model first assumes KAI-like polarization variations under a constant field inside the grain whose angle is tilted by theta. The second assumption is concerned with polarization variation under time-varying electric field. During a time period delta_t from t_now to t_next (=t_now+delta_t), the volume fractions of the downward- and upward-polarization domains changes according to the function c(t) under an electric field at t_now. By combining the derived polarization and an electrostatic potential equation across a gate stacked structure at t_next, an electric field at t_next is derived. Since the electric field and the volume fractions of the downward and upward domains are known at t_next, the calculation at the next delta_t step is possible. This procedure is repeated, and the EKAI model can simulate time-varying polarization reversal phenomena. Good agreement of the numerical results with the experimental indicates that the model is appropriate to simulate dynamic characteristics of FeFETs with polycrystalline ferroelectric films under swept and pulsed gate-voltages.Comment: 48 pages, 17 figure

Formation of Polyurethane Film Containing Silicone Polymer with Silanol Residue

The silicone polymers containing a silanol residue were synthesized from silica gel, while the polyurethanes (PUs) bearing a carboxyl moiety were prepared using 2,2-bis(hydroxymethyl)propionic acid (BHMPA) as one of the diol components. The fabrication of the PU films was carried out using these two polymers, then the tensile and thermal properties were investigated. Both the amounts of the carboxyl side groups of the PU chain and the residual silanol of the silicone polymer significantly affected the mechanical property of the film, in addition, the incorporation of 3-aminopropyltrimethoxysilane (APTMS) was quite effective for enhancing the elastic modulus (E). As a result, the film prepared from the polyurethane containing the BHMPA unit with a combination of APTMS and the silicone polymer, having a proper amount of silanol groups, showed the highest effect (E = 5.36 N/mm2), while that observed for the film prepared without using BHMPA and a silicone polymer was 2.10 N/mm2. An acid-base interaction between the carboxyl moiety of the PU and amino group of APTMS occurred, while the formation of the siloxane linkage through the silylation reaction between the trimethoxysilyl group of APTMS and silanol also took place

High-speed simulation of PCB emission and immunity with frequency-domain IC/LSI source models

Some recent results from research conducted in the EMC group at Okayama University are reviewed. A scheme for power-bus modeling with an analytical method is introduced. A linear macro-model for ICs/LSIs, called the LECCS model, has been developed for EMI and EMS simulation. This model has a very simple structure and is sufficiently accurate. Combining the LECCS model with analytical simulation techniques for power-bus resonance simulation provides a method for high-speed EMI simulation and decoupling evaluation related to PCB and LSI design. A useful explanation of the common-mode excitation mechanism, which utilizes the imbalance factor of a transmission line, is also presented. Some of the results were investigated by implementing prototypes of a high-speed EMI simulator, HISES. </p

Mental Health in Local Public Employees Affected by the Great East Japan Earthquake

The Great East Japan Earthquake was a complex disaster with a variety of destructive effects, including tsunami damage and damage due to the nuclear power plant accident. Local public employees who work for disaster-struck municipalities, while themselves disaster victims, are engaged in unimaginably difficult work including disaster relief and recovery. This study presents the outcomes of a two-stage panel survey on mental health conducted once in 2015 and once in 2016. The subjects were 672 local public employees in one disaster group that suffered tsunami damage and another disaster group that suffered damage from the nuclear disaster. Results showed the high-risk rate on the Impact of Event Scale-Revised (IES-R) was 11.9% for the tsunami-disaster group and 31.4% for the nuclear- accident group at Time 1. At Time 2, it was 8.9% for the tsunami-disaster group and 27.2% for the nuclear-accident group. From Time 1 to Time 2, the high-risk rate significantly decreased in both groups, but the percentage of high-risk persons remained elevated in the nuclear- accident group. In addition, factors predicting high risk for mental health issues by group were examined by logistic regression analysis. As a result, it was shown that the risk of traumatic stress and psychiatric disorders was increased by the occurrence of burnout as a result of high stress due to work experience after the disaster. Based on these results, future issues concerning stress care for local disaster public employees were discussed

Some Properties of Azuki Bean Mosaic Virus Isolated from Soybean Plants in Ibaraki Prefecture

Azuki bean mosaic virus (ABMV) was isolated from Glycine max showing mild mosaic and stunt on the leaves, collected in Ibaraki-Prefecture, in July, 1989. ABMV was transmitted by sap-inoculation to 8 species systemically and 14 species locally out of 33 species in 8 families and by aphids, Aulacorthum solani and Myzus persicae in a non-persistent manner.Seed transmission was recognized in 0.8% of the seeds of soybean cv."Iwate-wase-kurome" inoculated at seeding stage. The soybean plant infected with ABMV produced mottled seeds, which were radical- or saddle-like. The virus particles were flexuous rods, bout 750 nm in length. In ultrathin virus-infected tissues, cytoplasmic inclusions containing pinwheels and scrolls were observed in the cytoplasms. In DAS-ELISA, the virus reacted strongly with antiserum to ABMV. The weight of plants and seed of two soybean cv."Okuhara 1" and "Iwate-wase-kurome" inoculated with ABMV at the seedling stage was about 40～50% less than that of healthy plants.1989年7月、茨城県において軽いモザイクと委縮を生じたダイズからアズキモザイクウイルス（azuki bean mosaic virus,ABMV）を分離し、その諸症状を調べた。本ウイルスは汁液接種した8科33種の植物のうち3科8種が全身感染し、4科14種が局部病班または無病徴感染した。感染したダイズの種子はダイズモザイクウイルスと同様に放射または鞍掛状斑紋型の褐斑模様を発現した。また、幼苗感染したダイズ品種「岩手早生黒目」の種子で0.8％の伝染がも認められた。ジャガイモヒゲナガアブラムシとモモアカアブラムシで非永続的に伝搬した。本ウイルスの粒子は長さ約750nmのひも状であった。インゲンマメ病葉の細胞質内には束状に配列したウイルス粒子とpotyvirus特有の風車状および渦巻状の細胞質内封入体が観察された。本ウイルスはDAS-ELISAによりABMVに対する抗血清と反応陽性であった。ダイズの早生品種晩生品種ともに幼苗感染で収量が40～50％減少した。以上の結果から、本ウイルスはは既知のABMVと比較し、宿主範囲が広く、病原性のやや強い分離株とみなされた

Interleukin(IL)-36α and IL-36γ Induce Proinflammatory Mediators from Human Colonic Subepithelial Myofibroblasts

Background: Interleukin (IL)-36 cytokines are recently reported member of the IL-1 cytokine family. However, there is little information regarding the association between IL-36 cytokines and gut inflammation. In the present study, we investigated the biological activity of IL-36α and IL-36γ using human colonic subepithelial myofibroblasts (SEMFs). Methods: The mRNA expression and the protein expression of target molecules in SEMFs were evaluated using real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively. The intracellular signaling of IL-36 cytokines was analyzed using Western blot analysis and small interfering RNAs (siRNAs) specific for MyD88 adaptor proteins (MyD88 and IRAK1) and NF-κB p65. Results: IL-36α and IL-36γ significantly enhanced the secretion of IL-6 and CXC chemokines (CXCL1, CXCL2, and CXCL8) by SEMFs. The combination of IL-36α/γ and IL-17A or of IL-36α/γ and tumor necrosis factor (TNF)-α showed a synergistic effect on the induction of IL-6 and CXC chemokines. The mRNA expression of proinflammatory mediators induced by IL-36α and/or IL-36γ was significantly suppressed by transfection of siRNA for MyD88 or IRAK1. Both inhibitors of mitogen activated protein kinases (MAPKs) and siRNAs specific for NF-κBp65 significantly reduced the expression of IL-6 and CXC chemokines induced by IL-36α and/or IL-36γ. Conclusion: These results suggest that IL-36α and IL-36γ contribute to gut inflammation through the induction of proinflammatory mediators

Modulation bandwidth improvement of III-V/Si hybrid MOS optical modulator by reducing parasitic capacitance

In this work, we numerically and experimentally examined the impact of parasitic capacitance on the modulation bandwidth of a III-V/Si hybrid metal-oxide-semiconductor (MOS) optical modulator. The numerical analysis revealed that the parasitic capacitance between the III-V membrane and the Si slab should be considered to achieve high-speed modulation, particularly in the case of a thick gate oxide. We also fabricated a high-speed InGaAsP/Si hybrid MOS optical modulator with a low capacitance using a SiO2-embedded Si waveguide. The fabricated device exhibited a modulation efficiency of 0.245 Vcm and a 3 dB bandwidth of up to 10 GHz. Clear eye patterns with 25 Gbps non-return-to-zero (NRZ) modulation and 40 Gbps 4-level pulse amplitude modulation (PAM-4) were obtained without pre-emphasis