High-resistance resistors consisting of subthreshold-operated CMOS circuits

Shin’ichi Asai,Ken Ueno,Tetsuya Asai,Yoshihito Amemiya 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7

We propose a CMOS circuit that can be used as an equivalent of resistors. This circuit uses a differential pair consisting of diode-connected MOSFETs and operates as a high-resistance resistor when driven in the subthreshold region. Its resistance can be controlled in a range of 1-1000 ㏁ by adjusting the driving current for the circuit. The results of the fabrication and measurement of the circuit are described.

Structural Analysis of High Performance Ion-Gel Comprising Tetra-PEG Network

Asai, Hanako,Fujii, Kenta,Ueki, Takeshi,Sakai, Takamasa,Chung, Ung-il,Watanabe, Masayoshi,Han, Young-Soo,Kim, Tae-Hwan,Shibayama, Mitsuhiro American Chemical Society 2012 Macromolecules Vol.45 No.9

<P>The structure of Tetra-PEG ion gel, which is tetra-arm poly(ethylene glycol) (Tetra-PEG) network in ionic liquid (IL) and has recently established in our group and possesses high ion conductivity and high mechanical properties, was investigated as functions of polymer concentration (ϕ) and molecular weight (<I>M</I><SUB>w</SUB>) by using small-angle neutron scattering (SANS) measurements. The results were compared with those of Tetra-PEG hydrogel. The macromer solutions of tetra-amine terminated PEG (TAPEG) macromers, which is one of the two constituents forming Tetra-PEG network, were found to interpenetrate each other in IL and exhibited a scaling relationship, ξ ∼ ϕ<SUP>–3/4</SUP>, where ξ is the correlation length. The SANS functions, <I>I</I>(<I>q</I>), for the ion gels made by cross-end-coupling of TAPEG and TNPEG (tetra-arm PEG with active ester groups) were represented by the so-called Ornstein–Zernike equation, suggesting absence of frozen inhomogeneites. The same scaling relationship to the macromer solutions, ξ ∼ ϕ<SUP>–3/4</SUP>, was also obtained for the ion gels. Furthermore, the SANS curves were superimposed to a single master curve with <I>I</I>(<I>q</I>)/ξ<SUP>5/3</SUP>ϕ vs <I>ξq</I> irrespective of <I>M</I><SUB>w</SUB> and ϕ. In contrast, the Tetra-PEG ion gels made by reswelling of a dried hydrogel showed a large upturn, indicating that the ion gels made by the “re-swollen” method caused the network inhomogeneities.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2012/mamobx.2012.45.issue-9/ma300244u/production/images/medium/ma-2012-00244u_0001.gif'></P>

Blockade of the 4-1BB (CD137)/4-1BBL and/or CD28/CD80/CD86 costimulatory pathways promotes corneal allograft survival in mice

Asai, Tatsuhiko,Choi, Beom K.,Kwon, Patrick M.,Kim, Won Y.,Kim, Jung D.,Vinay, Dass S.,Gebhardt, Bryan M.,Kwon, Byoung S. Blackwell Publishing Ltd 2007 Immunology Vol.121 No.3

<P>Summary</P><P>To explore the roles of 4-1BB (CD137) and CD28 in corneal transplantation, we examined the effect of 4-1BB/4-1BB ligand (4-1BBL) and/or CD28/CD80/CD86 blockade on corneal allograft survival in mice. Allogeneic corneal transplantation was performed between two strains of wild-type (WT) mice, BALB/c and C57BL/6 (B6), and between BALB/c and B6 WT donors and various gene knockout (KO) recipients. Some of the WT graft recipients were treated intraperitoneally with agonistic anti-4-1BB or blocking anti-4-1BBL monoclonal antibody (mAb) on days 0, 2, 4 and 6 after transplantation. Transplanted eyes were observed over a 13-week period. Allogeneic grafts in control WT B6 and BALB/c mice treated with rat immunoglobulin G showed median survival times (MST) of 12 and 14 days, respectively. Allogeneic grafts in B6 WT recipients treated with anti-4-1BB mAb showed accelerated rejection, with an MST of 8 days. In contrast, allogeneic grafts in BALB/c 4-1BB/CD28 KO and B6 CD80/CD86 KO recipients had significantly prolonged graft survival times (MST, 52·5 days and 36 days, respectively). Treatment of WT recipients with anti-4-1BB mAb resulted in enhanced cellular proliferation in the mixed lymphocyte reaction and increased the numbers of CD4<SUP>+</SUP> CD8<SUP>+</SUP> T cells, and macrophages in the grafts, which correlated with decreased graft survival time, whereas transplant recipients with costimulatory receptor deletion showed longer graft survival times. These results suggest that the absence of receptors for the 4-1BB/4-1BBL and/or CD28/CD80/CD86 costimulatory pathways promotes corneal allograft survival, whereas triggering 4-1BB with an agonistic mAb enhances the rejection of corneal allografts.</P>

An AFM-based Edge Profile Measuring Instrument for Diamond Cutting Tools

Asai, Takemi,Motoki, Takenori,Gao, Wei,Ju, Bing-Feng,Kiyono, Satoshi Korean Society for Precision Engineering 2007 International Journal of Precision Engineering and Vol.8 No.2

This paper describes an atomic force microscope (AFM)-based instrument for measuring the nanoscale cutting edge profiles of diamond cutting tools. The instrument consists of a combined AFM unit and an optical sensor to align the AFM tip with the top of the diamond cutting tool edge over a submicron range. In the optical sensor, a aser beam is emitted from a laser diode along the Y-axis and focused to a small beam spot with a diameter of approximately $10{\mu}m$ at the beam waist, which is then received by a photodiode. The top of the tool edge is first brought into the center of the beam waist by adjusting it in the X-Z-plane while monitoring the variation in the photodiode output. The cutting tool is then withdrawn and its top edge position at the beam center is recorded. The AFM tip can also be positioned at the beam center in a similar manner to align it with the top of the cutting edge. To reduce electronic noise interference on the photodiode output and thereby enhance the alignment accuracy, a technique is applied that can modulate the photodiode output to an AC signal by driving the laser diode with a sinusoidal current. Alignment experiments and edge profile measurements of a diamond cutting tool were carried out to verify the performance of the proposed system.

MHD SIMULATIONS OF A MOVING SUB CLUMP WITH HEAT CONDUCTION

ASAI NAOKI,FUKUDA NAOYA,MATSUMOTO RYOJI The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5

High resolution observations of cluster of galaxies by Chandra have revealed the existence of an X-ray emitting comet-like galaxy C153 in the core of cluster of galaxies A2125. The galaxy C153 moving fast in the cluster core has a distinct X-ray tail on one side, obviously due to ram pressure stripping, since the galaxy C153 crossed the central region of A2125. The X-ray emitting plasma in the tail is substantially cooler than the ambient plasma. We present results of two-dimensional magnetohydrodynamic simulations of the time evolution of a sub clump like C153 moving in magnetized intergalactic matter. Anisotropic heat conduction is included. We found that the magnetic fields are essential for the existence of the cool X-ray tail, because in non-magnetized plasma the cooler sub clump tail is heated up by isotropic heat conduction from the hot ambient plasma and does not form such a comet-like tail.

KINETICS OF ABSORPTION OF HYDROGEN SULFIDE INTO AQUEOUS FE(3) SOLUTIONS

Asai, Satoru,Nakamura, Hidemi,Konishi, Yasuhiro 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.5

In our recent studies, absorption of H₂S into the aqueous Fe₂(SO₄)₃and FeCl₃, solutions with various values of ionic strength and pH was investigated in an agitated vessel with a flat interface. The experimental results for both systems revealed that the species which reacts with H₂S is FeOH^(2+). The absorption rates were explained by the theory of gas absorption with an irreversible (1, 1)-th order reaction between H₂S and FeOH^(2+). The reaction rate constants were independent of the ionic strength of the solution and correlated as a function of temperature. In this paper, kinetics and mechanism of these absorption reactions are reviewed and the identity for both systems is emphasized.

Aflatoxin Contamination of Red Chili Pepper From Bolivia and Peru, Countries with High Gallbladder Cancer Incidence Rates

Asai, Takao,Tsuchiya, Yasuo,Okano, Kiyoshi,Piscoya, Alejandro,Nishi, Carlos Yoshito,Ikoma, Toshikazu,Oyama, Tomizo,Ikegami, Kikuo,Yamamoto, Masaharu Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10

Chilean red chili peppers contaminated with aflatoxins were reported in a previous study. If the development of gallbladder cancer (GBC) in Chile is associated with a high level of consumption of aflatoxin-contaminated red chili peppers, such peppers from other countries having a high GBC incidence rate may also be contaminated with aflatoxins. We aimed to determine whether this might be the case for red chili peppers from Bolivia and Peru. A total of 7 samples (3 from Bolivia, 4 from Peru) and 3 controls (2 from China, 1 from Japan) were evaluated. Aflatoxins were extracted with acetonitrile:water (9:1, v/v) and eluted through an immuno-affinity column. The concentrations of aflatoxins B1, B2, G1, and G2 were measured using high-performance liquid chromatography (HPLC), and then the detected aflatoxins were identified using HPLC-mass spectrometry. In some but not all of the samples from Bolivia and Peru, aflatoxin B1 or aflatoxins B1 and B2 were detected. In particular, aflatoxin B1 or total aflatoxin concentrations in a Bolivian samples were above the maximum levels for aflatoxins in spices proposed by the European Commission. Red chili peppers from Bolivia and Peru consumed by populations having high GBC incidence rates would appear to be contaminated with aflatoxins. These data suggest the possibility that a high level of consumption of aflatoxin-contaminated red chili peppers is related to the development of GBC, and the association between the two should be confirmed by a case-control study.

デ―タ制約下における廢棄物處理有料化政策の評價

( Asai Yuichiro ) 동서대학교 일본연구센터 2014 次世代 人文社會硏究 Vol.10 No.-

High Frequency of TP53 but not K-ras Gene Mutations in Bolivian Patients with Gallbladder Cancer

Asai, Takao,Loza, Ernesto,Roig, Guido Villa-Gomez,Ajioka, Yoichi,Tsuchiya, Yasuo,Yamamoto, Masaharu,Nakamura, Kazutoshi Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.13

Although genetic characteristics are considered to be a factor influencing the geographic variation in the prevalence of gallbladder cancer (GBC), they have not been well studied in Bolivia, which has a high prevalence rate of GBC. The purpose of this study was to examine the frequency of TP53 and K-ras mutations in Bolivian patients with GBC and to compare them with our previous data obtained in other high-GBC-prevalence countries, namely Japan, Chile, and Hungary. DNA was extracted from cancer sites in paraffin-embedded tissue from 36 patients using a microdissection technique. TP53 mutations at exons 5 to 8 and K-ras mutations at codons 12, 13 and 61 were examined using direct sequencing techniques. The data obtained were compared with those in the other high-GBC-prevalence countries. Of the 36 patients, 18 (50.0%) had a TP53 mutation (one mutation in each of 17 patients and three mutations in one patient), and only one (2.8%) had a K-ras mutation. Of the 20 TP53 mutations, 12 were of the transition type (60.0%). This rate was significantly lower than that in Chile (12/12, P<0.05). In addition, three mutations were of the CpG transition type (15.0%), which is a feature of endogenous mutation. All three were found in the hot spot region of the TP53 gene. In contrast, G:C to T:A transversion was found in Bolivia, suggesting the presence of exogenous carcinogens. Our findings suggest that the development of GBC in Bolivia is associated with both exogenous carcinogens and endogenous mechanisms. The identification of an environmental risk factor for GBC is needed to confirm these findings.

The Structure and Function of Dynein heavy Chains

Asai, David J.,Lee, Seung-won Korean Society of Molecular Biology 1995 Molecules and cells Vol.5 No.4