bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of Fluorine Diffusion into Methyl Boron Carbon Nitride Film Using Low-Temperature Etching
Authors: Hara Makoto , Masuzumi Takuro , Lu Zhiming , Kimura Chiharu , Aoki Hidemitsu , Sugino Takashi
Published: April 2010

Boron carbon nitride containing a methyl group (methyl-BCN) is an attractive material as a low-dielectric-constant (low-k) interlayer for next-generation LSI interconnections. During dry etching with fluorine-based gases, the fluorine component diffuses into low-k films, especially porous low-k films. Thus, there is concern that residual fluorine induces low-k voiding and Cu corrosion. By low-temperature (-25 °C) etching, we have achieved an effective suppression of fluorine diffusion into the methyl-BCN film and a reduction in the amount of fluorocarbon polymer, while maintaining sufficient etching rates of the methyl-BCN film. The low-temperature etching of low-k films can be readily applied to the fabrication of next-generation LSI devices.
Effect of Magnetic Field on Permeability of Electroplated Permalloy for Microdevices
Authors: Kubo Eitaro , Ooi Naoki , Aoki Hidemitsu , Watanabe Daisuke , Jeong Jong-Hyeon , Kimura Chiharu , Sugino Takashi
Published: April 2010

We have investigated the effect of a magnetic field on an electroplated Ni79Fe21 film. We have succeeded in the formation of a Ni79Fe21 (permalloy) film with high permeability by applying the magnetic field vertical to the electric field during the electroplating process. In a conventional NiFe electroplating process, annealing is required to obtain a stable Ni79Fe21 film after electroplating. This process without annealing is useful for fabricating Ni79Fe21 films for flexible devices and complementary metal oxide semiconductor (CMOS) integration.
High-Performance Three-Terminal Fin Field-Effect Transistors Fabricated by a Combination of Damage-Free Neutral-Beam Etching and Neutral-Beam Oxidation
Authors: Wada Akira , Sano Keisuke , Yonemoto Masahiro , Endo Kazuhiko , Matsukawa Takashi , Masahara Meishoku , Yamasaki Satoshi , Samukawa Seiji
Published: April 2010

Three-terminal fin field-effect transistors (3T-FinFETs) were fabricated by neutral-beam oxidation (NBO) to form gate silicon dioxide (SiO2). The 3T-FinFET fabricated by NBO showed higher device performance – namely, a higher subthreshold slope and a higher effective mobility – than that fabricated by conventional thermal oxidation. It is considered that those improved subthreshold slope and mobility are due to the fact that the three-dimensional structure of a SiO2 film fabricated by NBO has a lower interfacial state density and a lower roughness than a similar structure fabricated by the conventional thermal oxidation of a SiO2 film. The reasons for the lower interfacial state density and lower roughness are the low temperature and lattice plane independence of NBO in comparison with conventional thermal oxidation processes.
Performance Improvement of Capacitorless Dynamic Random Access Memory Cell with Band-Gap Engineered Source and Drain
Authors: Tang Poren , Huang Ru , Wu Dake
Published: April 2010

A novel band-gap engineered source and drain floating body cell (BESD-FBC) for capacitorless dynamic random access memory (DRAM) Cell is proposed and investigated for the first time. The energy band offset with silicon–carbon source and drain can help to form a deeper potential well in the body region, which can effectively store more holes. Compared with normal FBC, BESD-FBC can obtain larger sensing margin and longer retention time due to more stored holes and small hole leakage current. These improvements show that the proposed BESD-FBC has great potentials for future high density capacitorless DRAM application.
A Highly Scalable Capacitor-Less Cell Having a Doubly Gated Vertical Channel
Authors: Kwon Wookhyun , Liu Tsu-Jae King
Published: April 2010

A double-gate transistor structure with a vertical channel is proposed and demonstrated via three-dimensional device simulations to be well suited for dynamic random access memory (DRAM) application. The double-gate transistor structure with a vertical channel (DGVC) cell occupies 4F2 area, provides for good retention characteristics (with immunity to disturbances), and is compatible with conventional memory process flows for stand-alone DRAM memories. In comparison with previous cell designs, the DGVC cell is more scalable, so that it is an excellent candidate for the continued scaling of DRAM technology to the 22-nm node and beyond.
A New Method to Extract the Charge Centroid in the Program Operation of Metal–Oxide–Nitride–Oxide–Semiconductor Memories
Authors: Fujii Shosuke , Yasuda Naoki , Fujiki Jun , Muraoka Kouichi
Published: April 2010

We proposed and demonstrated a new method to extract the charge centroid of metal–oxide–nitride–oxide–semiconductor (MONOS) devices. Comparing with other existing methods for charge centroid evaluation, our new method has the advantage of simplicity and the compatibility with other test sequences of memory cell capacitors. Using our method, we investigated the dependence of charge centroid on the thickness of SiN layer. It is found that the charge centroid of the 14-nm-thick SiN MONOS is located around the middle of the SiN layer, while the 5-nm-thick SiN MONOS has the centroid at the SiN/Al2O3 interface. These results indicate that the available trap sites during program operation are dependent on the thickness of the SiN layer.
Study of Charge Trap Sites in SiN Films by Hard X-ray Photoelectron Spectroscopy
Authors: Kosemura Daisuke , Takei Munehisa , Nagata Kohki , Akamatsu Hiroaki , Hattori Maki , Katayama Daisuke , Nishita Tatsuo , Hirota Yoshihiro , Machida Masatake , Son Jin-Young , Koganezawa Tomoyuki , Hirosawa Ichiro , Ogura Atsushi
Published: April 2010

Hard X-ray photoelectron spectroscopy (HAX-PES) was performed at SPring-8, and has enabled us to study the bulk properties of SiN films deposited by microwave plasma-enhanced chemical vapor deposition and deeply buried SiN/SiO2 interfaces, owing to the large inelastic mean free path of a photoelectron with a high kinetic energy. The defect states in the SiN films were examined by HAX-PES in order to verify the charge-trapping mechanism in a silicon–oxide–nitride–oxide–silicon flash memory device. X-ray reflectometry (XRR) was also performed at SPring-8. There is a complementary relationship between photoelectron spectroscopy and XRR. This methodology is proposed in this paper as a powerful tool for examining material properties. The detailed depth profile analysis of the chemical states in the SiN films obtained by angle-resolved HAX-PES also helped us to examine the charge-trapping mechanism.
Pixel Scaling in Complementary Metal Oxide Silicon Image Sensor with Lateral Overflow Integration Capacitor
Authors: Sakai Shin , Tashiro Yoshiaki , Kawada Shun , Kuroda Rihito , Akahane Nana , Mizobuchi Koichi , Sugawa Shigetoshi
Published: April 2010

Two wide dynamic range (DR) complementary metal oxide silicon (CMOS) image sensors (CIS) with lateral overflow integration capacitor (LOFIC) have been developed in order to scale down the pixel size. A checker-pattern CIS has achieved high area-efficiency for the full well capacity (FWC) by introducing the rectangle structure and placing the color-filters and on-chip microlens along the direction at an angle of 45°. A shared two pixels CIS has achieved small pixel pitch by introducing a lateral overflow gate that overflows over-saturated photoelectrons from the photodiode to the LOFIC directly. These CISs were fabricated using the 0.18-µm 2-polycrystalline 3-metal CMOS technology with buried-pinned-photodiode process and achieved the high FWC, low noise, wide DR and high resolution performances. These structures are effective for obtaining the small pixel size with the advantageous characteristics of LOFIC CIS. In this paper, these structures, operation methods and measurement results of these CISs have been discussed.
A New Differential-Amplifier-Based Offset-Cancellation Sense Amplifier for Speed-Improvement of High-Density Static Random Access Memories in Scaled-Down Complementary Metal–Oxide–Semiconductor Technology
Authors: Ikeda Hidetoshi , Takeda Koichi , Nomura Masahiro , Hayashi Yoshihiro
Published: April 2010

A new differential-amplifier-based offset-cancellation sense amplifier (DOCSA) is proposed in order to improve operation speed of high-density, six-transistor-cell static random access memories (SRAMs) in scaled-down complementary metal–oxide–semiconductor (CMOS) technology. 40-nm node CMOS test chips were fabricated and measured to demonstrate the successful operation and performance of DOCSA. Simulated offset voltage of DOCSA was 60% compared to that of a conventional latch-type sense amplifier with the same input capacitance, and the bit-line delay in an SRAM is expected to be 60% by using DOCSA. The standard deviation of measured offset voltage in DOCSA agreed well with that of the simulated one. Combination of CMOS scaling and deviation-relief circuit technology becomes important in advanced LSI technology.
RF Signal Generator Based on Time-to-Analog Converter in 0.18 µm Complementary Metal Oxide Semiconductor
Authors: Nakano Kazuo , Amakawa Shuhei , Ishihara Noboru , Masu Kazuya
Published: April 2010

In this paper, we propose an inductorless scalable RF signal generator from a digital pulse signal. Conventionally, digital-to-analog converters (DACs) generate analog signals by summing quantized voltage steps digitally. However, the DACs are not suitable for low-voltage operation in the fine complementary metal oxide semiconductor (CMOS) IC because the required quantized step becomes smaller as the CMOS process becomes finer. To overcome this, a time-to-analog conversion technique is suggested. The suggested circuit can advance the time step resolution and the low-voltage operation is possible. A prototypal time-to-analog circuit that generates sinusoidal waveforms from digital RF input was fabricated using 0.18-µm CMOS technology. The frequency was 128 MHz and the output power was -6.6 dBm. The output levels of the second and third harmonics were -23 and -37 dBc, respectively. The time-to-analog conversion technology suggested could become more attractive in the future if finer CMOS technologies that can realize higher time resolution are applied.
An Optimal Design Method for Complementary Metal Oxide Semiconductor Even-Stage Ring Oscillators Containing Latches
Authors: Kohara Yusuke , Asano Masaharu , Kawakami Yoshihiro , Uchida Yasuhisa , Koike Hiroki , Nakamura Kazuyuki
Published: April 2010

This paper describes a design method for complementary metal oxide semiconductor (CMOS) ring oscillators composed of even-stage inverters. First, we propose a quantitative method to evaluate oscillation stability for an even-stage ring oscillator with a CMOS latch. The method uses static noise margin analysis to evaluate the static random access memory (SRAM) cell's data storage stability, by observing the similarity between the oscillator and SRAM cell circuitry. Next, the method is extended to oscillators with multiple latches. Finally, by analyzing oscillation stability using this method, we find that the range of stable oscillation conditions can be drastically widened by adding multiple single-channel latch circuits, and also by an appropriate design of their polarities and insertion positions. We also clarify through Monte Carlo simulations, that the optimized oscillator circuit is robust under process, voltage and temperature fluctuations and device characteristic variations.
Electrical Properties of Metal–Insulator–Semiconductor Capacitors on Freestanding GaN Substrate
Authors: Kim Eunhee , Soejima Narumasa , Watanabe Yukihiko , Ishiko Masayasu , Kachi Tetsu
Published: April 2010

The electrical properties of GaN metal–insulator–semiconductor (MIS) capacitors with as-grown SiO2, annealed SiO2, and SiN
x
insulators were investigated by capacitance–voltage (C–V), current–voltage (I–V), and time-dependent dielectric breakdown (TDDB) measurements. The MIS capacitor with the SiN
x
insulator was determined to have a lower interface trap density of 1×1011 cm-2 eV-1 than the MIS capacitors with the as-grown and annealed SiO2 insulators. In addition, the dielectric lifetime of the SiN
x
insulator was extrapolated to be more than 20 years at an even high voltage at room temperature. These results indicate that the high insulator/GaN interface quality and high reliability required for high-performance power devices can be achieved by the deposition of the SiN
x
insulator on GaN.
Compressively Strained InxAl1-xN/Al0.22Ga0.78N/GaN (x = 0.245–0.325) Heterostructure Field Effect Transistors with Regrown AlGaN Contact Layers
Authors: Hiroki Masanobu , Maeda Narihiko , Shigekawa Naoteru
Published: April 2010

Compressively strained In
x
Al1-x
N (15 nm)/Al0.22Ga0.78N (3 nm)/GaN heterostructure field effect transistors (FETs) with regrown AlGaN contact layers were fabricated. The increase in compressive strain in InAlN reduced the polarization charge, i.e., the density of two-dimensional electron gas decreased from 6.5 ×1012 to 1.3 ×1012 cm-2 as the In content of InAlN increased from 0.245 to 0.325. With the insertion of the AlGaN layer, electron mobility of as high as 1570 cm2 V-1 s-1 was achieved at the In content of 0.245. Selectively regrown AlGaN contact layers reduced the sheet resistance from 17,000 to 584 Ω/sq. at the access layer for In0.325Al0.675N/Al0.22Ga0.78N/GaN. We fabricated FETs with this structure. The FETs without the regrown AlGaN contact layer did not operate at all owing to the high resistance. In contrast, the devices with the regrown AlGaN did. The maximum transconductance is 60 mS/mm, and the drain current is 0.11 A/mm. The threshold voltage becomes shallower, changing from -3.2 to -0.2 V with the increase in In content from 0.245 to 0.325. These results indicate that it is possible to fabricate enhancement-mode FETs with InAlN/AlGaN/GaN heterostructures.
Very Smooth SiO2/SiC Interface Formed by Supercritical Water Oxidation at Low Temperature
Authors: Futatsuki Takashi , Oe Taro , Aoki Hidemitsu , Komatsu Naoyoshi , Kimura Chiharu , Sugino Takashi
Published: April 2010

We have formed a SiO2 layer on a SiC surface by supercritical water (SCW) oxidation at a much lower temperature (400 °C) than that of conventional SiC thermal oxidation (1100 °C). This rapid oxidation at a low temperature is attributed to the high density of the oxidizers (H2O and O2) under a high-pressure condition. We also revealed that SCW oxidation under suitable conditions suppresses the formation of SiO2/SiC interface microroughness. The smooth SiO2/SiC interface obtained by this low-temperature oxidation process is expected to contribute to improving the mobility performance of future SiC field-effect transistors (FETs).
ZnO Channel Waveguides for Nonlinear Optical Applications
Authors: Teraoka Edgar Yoshio Morales , Kita Tomohiro , Tsukazaki Atsushi , Kawasaki Masashi , Ohtera Yasuo , Yamada Hirohito
Published: April 2010

ZnO channel waveguides were fabricated for the first time, for the purpose of being used in nonlinear optical applications. Wide-bandgap ZnO was chosen for the core material to avoid two-photon absorption at wavelengths above 800 nm which are used for biomedical applications. We calculated the single-mode conditions and group-velocity dispersion of the propagating modes for the waveguides. We also fabricated channel waveguides using single-crystal ZnO thin film grown on sapphire substrate. Measured propagation losses with a cut-back method were approximately 3 to 6 dB/mm for single-mode waveguides.
Fabrication and Optical Characterization of Self-Standing Wide-Gap Nanocrystalline Silicon Layers
Authors: Mentek Romain , Gelloz Bernard , Koshida Nobuyoshi
Published: April 2010

The fabrication of self-standing thin layers of nanocrystalline silicon to use as a top-cell in multijunction silicon-based solar cells has been investigated. Study on the effects of different oxidation processes such as rapid thermal oxidation (RTO) and high-pressure water vapor annealing (HWA) on the optical characteristics has also been carried out. Samples treated with a combination of RTO and HWA feature particularly interesting photonic features such as efficient and stable blue photoluminescence as well as a blue shift of the absorption edge corresponding to a widening of the band gap due to quantum confinement in nanodots of silicon. Such interesting properties are expected to lead to potential application in the photovoltaic field.
Growth and Characterization of High Quality a-Plane InGaN/GaN Single Quantum Well Structure Grown by Multibuffer Layer Technique
Authors: Song Hooyoung , Kim Jin Soak , Kim Eun Kyu , Seo Yong Gon , Hwang Sung-Min
Published: April 2010

Nonpolar (1120) a-plane InGaN/GaN single quantum well (SQW) structure has been grown using a multi buffer layer on a (1102) r-plane sapphire substrate. The effects on the lattice constants of the a-plane GaN template caused by reactor pressure and V/III ratio of the first buffer layer were studied to improve the crystal quality. Under optimum growth conditions, the full widths at half maximum (FWHMs) of (1120) X-ray rocking curves along the c- and m-axis orientations were 430 and 530 arcsec, respectively. The optical characteristics of the nonpolar InGaN SQW determined from excitation-power-dependent photoluminescence and temperature-dependent photoluminescence spectra showed the absence of the quantum-confined Stark effect.
Measurement of Electron Spin States in a Semiconductor Quantum Well Using Tomographic Kerr Rotation
Authors: Inagaki Takahiro , Kosaka Hideo , Rikitake Yoshiaki , Imamura Hiroshi , Mitsumori Yasuyoshi , Edamatsu Keiichi
Published: April 2010

Spin coherence is essential for spin-based quantum information technology. The conventional spin measurement technique, however, requires an extra step of spin manipulation or precession to measure the electron spin coherence. To measure the electron spin coherence directly, we have developed the tomographic Kerr rotation (TKR) method, which is based on the magneto-optical Kerr effect on the condition of the coherent transfer of light polarization states into electron spin states in a GaAs/AlGaAs quantum well. The TKR method allows measurement of the coherent superposition state of electron spins |±y>e = (|↑>e±i|↓>e)/√2 in addition to conventionally measured ±z states (|↑>e or |↓>e) (which merely indicate the population of electron spins). Here we demonstrate that electron spin coherence can be measured by linearly polarized probe light to show that TKR is independent of the choice of probe light polarization. We also describe a method to distinguish TKR from the conventional magnetic circular dichroism (MCD) effect.
Electric Double Layer Gate Field-Effect Transistors Based on Si
Authors: Yanase Takashi , Shimada Toshihiro , Hasegawa Tetsuya
Published: April 2010

Electric double layer field-effect transistors (EDL-FETs) were fabricated using single crystal Si wafer as the active semiconductor and various characteristics were studied including dynamic response against step-function gate bias. The static FET mobility was more than 100 cm2 V-1 s-1. The response time of the drain current was 20 µs for ionic liquid and 3 ms for poly(ethylene glycol) (PEG) solution of LiBF4. Unexpected fast response was observed at a certain “speed up bias” condition. This effect will be useful to switching circuits using EDL-FETs.
Organic Thin-Film Transistors with Tailored Liquid Sources of HfO2 as a High-κ Insulator
Authors: Nishizawa Ryota , Naka Shigeki , Okada Hiroyuki , Suzuki Kazuyuki , Kato Kazumi
Published: April 2010

Organic thin-film transistors (OTFTs) with tailored liquid sources of HfO2 as a high-κ insulator were investigated. To investigate the effect of UV irradiation, two types of light source were tested. The contact angles of water and polycrystalline condition of a pentacene were systematically changed and the resultant OTFT characteristics were also changed. The field-effect mobilities and on–off ratios obtained using a high-pressure mercury lamp and a deep-UV lamp as irradiation sources were 0.035 and 0.10 cm2 V-1 s-1, and 24 and 3 ×103, respectively.
Front-Light Source Using Inverted Organic Light-Emitting Diodes with Microcathode Arrays
Authors: Urata Kohei , Naka Shigeki , Okada Hiroyuki
Published: April 2010

We have demonstrated an organic light-emitting diode (OLED) front-light source with a blinding microcathode array on a transparent electrode and a top-emission structure. Contrast ratio was improved by inserting MoO3 at the indium–tin-oxide (ITO)/Al interface. In a device of glass substrate/ITO/MoO3/meshed Al/lithium fluoride (LiF)/tris(8-hydroxyquinolinato) aluminum(III) (Alq3)/bis[N-(1-naphthyl)-N-phenyl] benzidine (α-NPD)/MoO3/semitransparent Au structure, the maximum luminance of top-side emission was 1,140 cd/m2, and the contrast ratio was 19:1. The transmittance was 44% at 555 nm.
Increasing the Fill Factor and Power Conversion Efficiency of Polymer Photovoltaic Cell Using V2O5/CuPc as a Buffer Layer
Authors: Chiang Wang-Ta , Su Shui-Hsiang , Lin Yan-Fu , Yokoyama Meiso
Published: April 2010

In this study, we investigated the high fill factor (FF) and high power conversion efficiency (PCE) of organic photovoltaic (OPV) cells using a dual hole-transporting layer (HTL) of vanadium oxide (V2O5)/copper phthalocyanine (CuPc) as a buffer layer. The OPV cell configuration consists of indium tin oxide (ITO)/V2O5/CuPc/poly(3-hexylthiophene) (P3HT):phenyl C61-butyric acid methylester (PCBM)/LiF/Al. The FF and PCE of the device with a V2O5/CuPc buffer layer are approximately threefold and tenfold, respectively, greater than those of a conventional device without the buffer layer. The FF and PCE of the device are 62.2 and 2.11%, respectively, under a simulated AM1.5G illumination of 100 mW/cm2. The increased PCE and FF of the device are obtained using a V2O5/CuPc buffer layer, which is attributed to the stepwise hole-transporting configuration and the increased optical absorption from the anode.
Oriented Growth of Sexithiophene Induced by Edge of Metal Electrodes
Authors: Ikeda Susumu , Wada Yasuo , Saiki Koichiro
Published: April 2010

Recently it has been shown that the “graphoepitaxy” of organic semiconductor α-sexithiophene (6T) occurs on artificial periodic grooves fabricated on thermally-oxidized Si substrates. In the present study, similarly oriented growth of 6T thin films was found around the edge of metal electrodes. Using this phenomenon to realize single crystalline organic transistors, substrates with short channel Au electrodes were fabricated by photolithography, and 6T films were grown on these substrates by molecular beam deposition. The {010} planes of 6T crystals tended to face the wall of the channel (electrode edge), probably due to the chemical affinity of Au for S atoms in 6T molecules. The transistor characteristics of the test device were measured, and the results suggested that this orientation control technique using the shape of electrodes would lead to improvements in device performance.
Light Addressable Potentiometric Sensor with Fluorine-Terminated Hafnium Oxide Layer for Sodium Detection
Authors: Lue Cheng-En , Lai Chao-Sung , Chen Hsin-Yu , Yang Chia-Ming
Published: April 2010

In this study, post-CF4 plasma surface treatment of light addressable potentiometric sensor (LAPS) with a HfO2-sensing membrane was carried out. pH sensitivity decreased but pNa sensitivity increased with fluorine incorporation. The highest pNa sensitivity was 31.8 mV/pNa, which was optimized with 3 min post CF4 plasma treatment. The results showed a high possibility for sensing sodium ions using an inorganic-sensing membrane and a fabrication process. Moreover, on the basis of the analysis of atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) spectra, a sensing mechanism was developed.
CoFeB Inserted Perpendicular Magnetic Tunnel Junctions with CoFe/Pd Multilayers for High Tunnel Magnetoresistance Ratio
Authors: Mizunuma Kotaro , Ikeda Shoji , Yamamoto Hiroyuki , Gan Hua Dong , Miura Katsuya , Hasegawa Haruhiro , Hayakawa Jun , Ito Kenchi , Matsukura Fumihiro , Ohno Hideo
Published: April 2010

The effect of Co20Fe60B20 insertion on tunnel magnetoresistance (TMR) properties of MgO barrier magnetic tunnel junctions (MTJs) was studied with Co90Fe10/Pd multilayer electrodes showing perpendicular anisotropy. The TMR ratio, which depended on the sputtering power density of the CoFeB layer, reached 43% at 1.77 W/cm2 in MTJs with a 1.8-nm-thick CoFeB layer inserted on both sides of the MgO barrier. With increasing CoFeB layer thickness, the optimal annealing temperature (T
a) realizing the maximum TMR ratio increased along with the TMR ratio. The MTJs with 3.0-nm-thick CoFeB deposited at 1.77 W/cm2 showed a TMR ratio of 91% at T
a = 250 °C, where the perpendicular magnetic anisotropy is maintained.
Effects of Shell Strain on Valence Band Structure and Transport Properties of Ge/Si1-xGexCore–Shell Nanowire
Authors: Xu Honghua , Liu Xiaoyan , Du Gang , Zhao Yuning , He Yuhui , Fan Chun , Han Ruqi , Kang Jinfeng
Published: April 2010

Various Si1-xGexshell strains induced by changing the thickness or tuning the Ge and Si contents as well as by modulating the valence band structure and hole transport characteristics of core/shell nanowire field effect transistors (FETs) have been calculated. As Si1-xGexshell thickness increases, the strained valence subbands shift upwards and warp markedly. Most of the corresponding hole effective masses of the top five subbands decrease. Meanwhile, the hole mobility of the Ge(110) nanowire increases with increasing shell thickness. As the Ge concentration in the Si1-xGexshell decreases, the strained valence subbands and hole mobility show similar shifts. As a result, our calculation indicates the possibility of improving the nanowire performance of heterostructure nanowire FETs.
Electron Transport Properties in Photo and Supersonic Wave Irradiated C60 Fullerene Nano-Whisker Field-Effect Transistors
Authors: Doi Tatsuya , Koyama Kyouhei , Chiba Yasuto , Tsuji Hajime , Ueno Misaki , Chen Shih-Ren , Aoki Nobuyuki , Bird Jonathan Paul , Ochiai Yuichi
Published: April 2010

We have investigated the irradiation effect of ultraviolet light (UV) and supersonic wave (SW) into fullerene nano-whisker (FNW) field-effect transistors (FET). FNW has been fabricated by liquid/liquid interfacial precipitation using a system of C60-saturated m-xylene and isopropyl alcohol. And the morphology of FNW has been observed by a scanning electron microscope. The UV irradiation effect of FNW-FET in vacuum was observed that field effect mobility reduced from 10-2 to 10-3 cm2 V-1 s-1. Also, SW irradiation in solution, the FNW-FET shows a large increase on/off ratio from 10 to 1000. There exists a clear improvement in FET performance by use of both UV and SW irradiation for FNW. Also, the effect of exposure in air has been discussed on their FET performance.
Lateral Back-to-Back Diode for Low-Capacitance Transient Voltage Suppressor
Authors: Dai Sheng-Huei , Peng Jeng-Jie , Chen Chia-Cheng , Lin Chrong-Jung , King Ya-Chin
Published: April 2010

In this paper, a transient voltage suppressor (TVS) using a native lateral back-to-back diode structure in conventional complementary metal–oxide–semiconductor (CMOS) technology is proposed. The capacitance, direct-current (DC) current–voltage (I–V) characteristics, and transmission line pulse (TLP) I–V characteristics of this lateral back-to-back diode are investigated. An optimization guideline for the lateral device is presented. The lateral structure is also suitable for the advanced wafer-level chip-scale package (WL-CSP) technology to meet the low capacitance and small footprint requirement for high-frequency or handheld device applications. This is a simple solution for a low-capacitance and low breakdown-voltage protection device against electrostatic discharge and electrical overstress in discrete or on-chip applications.
Hyperglycemia-mediated activation of the hexosamine biosynthetic pathway results in myocardial apoptosis
Authors: Rajamani Uthra , Essop M. Faadiel
Published: April 2010

The mechanisms mediating hyperglycemia-mediated myocardial cell death are poorly defined. Since elevated flux through the hexosamine biosynthetic pathway (HBP) is closely linked with the diabetic phenotype, we hypothesized that hyperglycemia-mediated oxidative stress results in greater O-GlcNAcylation (HBP end product) of the proapoptotic peptide BAD, thereby increasing myocardial apoptosis. H9c2 cardiomyoblasts were exposed to high glucose (33 mM) ± HBP modulators ± antioxidant treatment for 5 days vs. matched controls (5.5 mM), and we subsequently evaluated apoptosis by immunoblotting, immunofluorescence staining, and caspase activity measurements. In vitro reactive oxygen species (ROS) levels were quantified by 2′,7′-dichlorodihydrofluorescein diacetate staining (fluorescence microscopy and flow cytometry). We determined total and BAD O-GlcNAcylation, respectively, by immunoblotting and immunofluorescence microscopy. The current study shows that high glucose treatment of cells significantly increased the degree of apoptosis. In parallel, overall O-GlcNAcylation, BAD O-GlcNAcylation, and ROS levels were increased. HBP inhibition and antioxidant treatment attenuated these effects, while increased end product levels exacerbated it. As BAD-Bcl-2 dimer formation enhances apoptosis, we performed immunoprecipitation analysis and colocalization and found increased dimerization in cells exposed to hyperglycemia. Our study identified a novel pathway whereby hyperglycemia results in greater oxidative stress and increased HBP activation and BAD O-GlcNAcylation in H9c2 cardiomyoblasts. Since greater BAD-Bcl-2 dimerization increases myocardial apoptosis, this pathway may play a crucial role in diabetes-related onset of heart diseases.
oxLDL-induced decrease in lipid order of membrane domains is inversely correlated with endothelial stiffness and network formation
Authors: Shentu Tzu Pin , Titushkin Igor , Singh Dev K. , Gooch Keith J. , Subbaiah Papasani V. , Cho Michael , Levitan Irena
Published: April 2010

Oxidized low-density lipoprotein (oxLDL) is a major factor in development of atherosclerosis. Our earlier studies have shown that exposure of endothelial cells (EC) to oxLDL increases EC stiffness, facilitates the ability of the cells to generate force, and facilitates EC network formation in three-dimensional collagen gels. In this study, we show that oxLDL induces a decrease in lipid order of membrane domains and that this effect is inversely correlated with endothelial stiffness, contractility, and network formation. Local lipid packing of cell membrane domains was assessed by Laurdan two-photon imaging, endothelial stiffness was assessed by measuring cellular elastic modulus using atomic force microscopy, cell contractility was estimated by measuring the ability of the cells to contract collagen gels, and EC angiogenic potential was estimated by visualizing endothelial networks within the same gels. The impact of oxLDL on endothelial biomechanics and network formation is fully reversed by supplying the cells with a surplus of cholesterol. Furthermore, exposing the cells to 7-keto-cholesterol, a major oxysterol component of oxLDL, or to another cholesterol analog, androstenol, also results in disruption of lipid order of membrane domains and an increase in cell stiffness. On the basis of these observations, we suggest that disruption of lipid packing of cholesterol-rich membrane domains plays a key role in oxLDL-induced changes in endothelial biomechanics.
Inhibition of brown adipose tissue thermogenesis by neurons in the ventrolateral medulla and in the nucleus tractus solitarius
Authors: Cao Wei-Hua , Madden Christopher J. , Morrison Shaun F.
Published: April 2010

Neurons in the ventrolateral medulla (VLM) and in the nucleus tractus solitarius (NTS) play important roles in the regulation of cardiovascular and other autonomic functions. In the present study, we demonstrate an inhibition of brown adipose tissue (BAT) thermogenesis evoked by activation of neurons in the VLM, as well as by neurons in the intermediate NTS, of chloralose/urethane-anesthetized, artificially ventilated rats. Activation of neurons in either rostral VLM or caudal VLM with N-methyl-d-aspartate (12 nmol) reversed the cold-evoked increase in BAT sympathetic nerve activity (SNA), BAT temperature, and end-expired CO2. Disinhibition of neurons in either VLM or NTS with the GABAA receptor antagonist, bicuculline (30 pmol), reversed the increases in BAT SNA, BAT temperature, and end-expired CO2 that were elicited 1) by cold defense; 2) during the febrile model of nanoinjection of prostaglandin E2 into the medial preoptic area; 3) by activation of neurons in the dorsomedial hypothalamus or in the rostral raphe pallidus (rRPa); or 4) by the μ-opioid receptor agonist fentanyl. Combined, but not separate, inhibitions of neurons in the VLM and in the NTS, with the GABAA receptor agonist, muscimol (120 pmol/site), produced increases in BAT SNA, BAT temperature, and expired CO2, which were reversed by nanoinjection of glycine (30 nmol) into the rRPa. These findings suggest that VLM and NTS contain neurons whose activation inhibits BAT thermogenesis, that these neurons receive GABAergic inputs that are active under these experimental conditions, and that neurons in both sites contribute to the tonic inhibition of sympathetic premotor neuronal activity in the rRPa that maintains a low level of BAT thermogenesis in normothermic conditions.
Overexpression of HSP10 in skeletal muscle of transgenic mice prevents the age-related fall in maximum tetanic force generation and muscle cross-sectional area
Authors: Kayani Anna C. , Close Graeme L. , Dillmann Wolfgang H. , Mestril Ruben , Jackson Malcolm J. , McArdle Anne
Published: April 2010

Skeletal muscle atrophy and weakness are major contributors to frailty and impact significantly on quality of life of older people. Muscle aging is characterized by a loss of maximum tetanic force (Po) generation, primarily due to muscle atrophy, to which mitochondrial dysfunction is hypothesized to contribute. We hypothesized that lifelong overexpression of the mitochondrial heat shock protein (HSP) HSP10 in muscle of mice would protect against development of these deficits. Pogeneration by extensor digitorum longus muscles of adult and old wild-type and HSP10-overexpressing mice was determined in situ. Muscles were subjected to damaging lengthening contractions, and force generation was remeasured at 3 h or 28 days to examine susceptibility to, and recovery from, damage, respectively. Muscles of old wild-type mice had a 23% deficit in Pogeneration and a 10% deficit in muscle cross-sectional area compared with muscles of adult wild-type mice. Overexpression of HSP10 prevented this age-related fall in Pogeneration and reduction in cross-sectional area observed in muscles of old wild-type mice. Additionally, overexpression of HSP10 protected against contraction-induced damage independent of age but did not improve recovery if damage occurred. Preservation of muscle force generation and CSA by HSP10 overexpression was associated with protection against the age-related accumulation of protein carbonyls. Data demonstrate that development of age-related muscle weakness may not be inevitable and show, for the first time, that lifelong overexpression of an HSP prevents the age-related loss of Pogeneration. These findings support the hypothesis that mitochondrial dysfunction is involved in the development of age-related muscle deficits.
An apical expression signal of the renal type IIc Na+-dependent phosphate cotransporter in renal epithelial cells
Authors: Ito Mikiko , Sakurai Aya , Hayashi Keiji , Ohi Akiko , Kangawa Natsumi , Nishiyama Takashi , Sugino Sakiko , Uehata Yoko , Kamahara Akihiro , Sakata Masae , Tatsumi Sawako , Kuwahata Masashi , Taketani Yutaka , Segawa Hiroko , Miyamoto Ken-ichi
Published: April 2010

The type IIc Na+-dependent phosphate cotransporter (NaPi-IIc) is specifically targeted to, and expressed on, the apical membrane of renal proximal tubular cells and mediates phosphate transport. In the present study, we investigated the signals that determine apical expression of NaPi-IIc with a focus on the role of the N- and the C-terminal tails of mouse NaPi-IIc in renal epithelial cells [opossum kidney (OK) and Madin-Darby canine kidney cells]. Wild-type NaPi-IIc, the cotransporter NaPi-IIa, as well as several IIa-IIc chimeras and deletion mutants, were fused to enhanced green fluorescent protein (EGFP), and their cellular localization was analyzed in polarized renal epithelial cells by confocal microscopy and by cell-surface biotinylation. Fluorescent EGFP-fused NaPi-IIc transporter proteins are correctly expressed in the apical membrane of OK cells. The apical expression of N-terminal deletion mutants (deletion of N-terminal 25, 50, or 69 amino acids) was not affected by truncation. In contrast, C-terminal deletion mutants (deletion of C-terminal 45, 50, or 62 amino acids) did not have correct apical expression. A more detailed mutational analysis indicated that a domain (amino acids WLHSL) in the cytoplasmic C terminus is required for apical expression of NaPi-IIc in renal epithelial cells. We conclude that targeting of NaPi-IIc to the apical cell surface is regulated by a unique amino acid motif in the cytoplasmic C-terminal domain.
Orientation Anisotropies in Human Visual Cortex
Authors: Mannion Damien J. , McDonald J. Scott , Clifford Colin W. G.
Published: April 2010

Representing the orientation of features in the visual image is a fundamental operation of the early cortical visual system. The nature of such representations can be informed by considering anisotropic distributions of response across the range of orientations. Here we used functional MRI to study modulations in the cortical activity elicited by observation of a sinusoidal grating that varied in orientation. We report a significant anisotropy in the measured blood-oxygen level-dependent activity within visual areas V1, V2, V3, and V3A/B in which horizontal orientations evoked a reduced response. These visual areas and hV4 showed a further anisotropy in which increased responses were observed for orientations that were radial to the point of fixation. We speculate that the anisotropies in cortical activity may be related to anisotropies in the prevalence and behavioral relevance of orientations in typical natural environments.
Study on Photon Transport Problem Based on the Platform of Molecular Optical Simulation Environment
Authors: Peng Kuan , Gao Xinbo , Liang Jimin , Qu Xiaochao , Ren Nunu , Chen Xueli , Ma Bin , Tian Jie
Published: April 2010

As an important molecular imaging modality, optical imaging has attracted increasing attention in the recent years. Since the physical experiment is usually complicated and expensive, research methods based on simulation platforms have obtained extensive attention. We developed a simulation platform named Molecular Optical Simulation Environment (MOSE) to simulate photon transport in both biological tissues and free space for optical imaging based on noncontact measurement. In this platform, Monte Carlo (MC) method and the hybrid radiosity‐radiance theorem are used to simulate photon transport in biological tissues and free space, respectively, so both contact and noncontact measurement modes of optical imaging can be simulated properly. In addition, a parallelization strategy for MC method is employed to improve the computational efficiency. In this paper, we study the photon transport problems in both biological tissues and free space using MOSE. The results are compared with Tracepro, simplified spherical harmonics method (SPn), and physical measurement to verify the performance of our study method on both accuracy and efficiency.
Statin Use and Colorectal Adenoma Risk: Results from the Adenoma Prevention with Celecoxib Trial
Authors: Bertagnolli Monica M. , Hsu Meier , Hawk Ernest T. , Eagle Craig J. , Zauber Ann G.
Published: April 2010

Statins are widely prescribed for cardiovascular disease prevention and also commonly used in patients at high risk for colorectal cancer. We report the results of a planned secondary analysis of the relationship between statin use and colorectal adenoma risk in a large chemoprevention trial. The Adenoma Prevention with Celecoxib (APC) trial randomized 2,035 adenoma patients to receive placebo (679 patients), 200 mg celecoxib twice daily (bid; 685 patients), or 400 mg celecoxib bid (671 patients). The study collected complete medical history and medication use data and performed colonoscopic surveillance to 5 years after study enrollment. The effects of statin use on newly detected adenomas and cardiovascular adverse events were analyzed as time-dependent variables by multivariable Cox regression. Statins were used by 36% (n = 730) of APC trial participants. When adjusted for covariates including cardioprotective aspirin use, age, and sex, participants on the placebo arm who used statins at any time had no benefit over 5 years compared with never users (risk ratio, 1.24; 95% confidence interval, 0.99-1.56; P = 0.065). Statin use for >3 years increased adenoma risk over 5 years (risk ratio, 1.39; 95% confidence interval, 1.04-1.86; P = 0.024). For all comparisons of patients treated with celecoxib, adenoma detection rates for statin users and nonusers were equivalent. Consistent with their use in patients at high risk, cardiovascular serious adverse events were more common among statin users. For patients at high risk of colorectal cancer, statins do not protect against colorectal neoplasms and may even increase the risk of developing colorectal adenomas. Cancer Prev Res; 3(5); 588–96. ©2010 AACR.
Statins and the Colorectum: Hope for Chemoprevention?
Authors: Baron John A.
Published: April 2010

This perspective on Bertagnolli et al. (beginning on p. 588 in this issue of the journal) and Lipkin et al. (beginning on p. 597) considers the likelihood that statins have chemopreventive efficacy in the large bowel. An observational analysis within a clinical trial of celecoxib found no benefit of statin use on the risk of colorectal adenomas (and some suggestions of an adverse effect). On the other hand, variation in the 3-hydroxy-3-methylglutaryl coenzyme A reductase gene modified the association of statins with risk of colorectal cancer. The perspective discusses the implications of these data and how they fit into the context of previous investigations. Cancer Prev Res; 3(5); 573–5. ©2010 AACR.
Stakeholder Perspectives on a Risk-Benefit Framework for Genetic Testing
Authors: Roth Joshua A. , Garrison Jr. Louis P. , Burke Wylie , Ramsey Scott D. , Carlson Rick , Veenstra David L.
Published: April 2010

A key to accelerating the appropriate integration of genomic applications into healthcare in the coming decades will be the ability to assess the tradeoffs between clinical benefits and clinical risks of genetic tests in a timely manner. Several factors limit the ability of stakeholders to achieve this objective, including the lack of direct evidence, the lack of a framework to quantitatively assess risk and benefit, and the lack of a formal analytic approach to assess uncertainty. We propose that a formal, quantitative risk-benefit framework may be particularly useful for assessing genetic tests intended to influence health outcomes, and communicating the potential clinical benefits, harms, and uncertainty to stakeholders. As part of the development process for such a framework, a stakeholder meeting was held in Seattle (Wash., USA) in December of 2008, with the objective of discussing a risk-benefit framework, using warfarin pharmacogenomics as a case study. Participants engaged in focused discussion to elucidate the potential role of genetic test risk-benefit analysis in informing decision-making, categorizing genetic tests and directing research prioritization. This research investigation focuses on qualitative analysis of responses elicited from workshop participants during the proceedings of the workshop session. The major findings of the workshop were: (1) stakeholder support for risk-benefit modeling as a tool to structure discussion of the clinical utility of genetic tests; (2) desire for the modeling process to be iterative, transparent, and parsimonious in its presentation to stakeholders, and (3) some concern with the use of quality-adjusted life-years in the evaluation process. The meeting’s findings emphasize the potential utility of risk-benefit analysis in genetic test evaluation, and highlight key areas for future research and stakeholder consensus-building.
High Cumulative Doses of Pegylated Liposomal Doxorubicin Are Not Associated with Cardiac Toxicity in Patients with Gynecologic Malignancies
Authors: Kesterson Joshua P. , Odunsi Kunle , Lele Shashikant
Published: April 2010

Purpose: The purpose of this study was to determine the cardiac safety of pegylated liposomal doxorubicin (PLD) in patients receiving high cumulative doses of PLD. Materials and Methods: A retrospective chart review of women with gynecologic malignancies treated at Roswell Park Cancer Institute from 2002 through 2007 who received cumulative doses of PLD ≧400 mg/m2 was performed. Results: Forty-two of 116 patients met the inclusion criteria. The mean age at initiation of PLD therapy was 63 years. The mean cumulative dose of PLD was 663.9 mg/m2 (range 400–1,524 mg/m2). The mean cumulative number of cycles of PLD given was 9.8 (range 5–25). Multigated acquisition (MUGA) scans were obtained in 93% (39/42) of patients prior to or immediately following their first dose of PLD. The mean baseline ejection fraction was 63% (range 49–76%). Follow-up MUGA scans were performed on 7 patients (17%). Two of these patients had a decrease in their ejection fraction, but of only 3 and 1%. The remaining 5 patients who had follow-up MUGA scans had an average increase in their left ventricular ejection fraction of 4% (range 1–9%). No patients developed clinical evidence of congestive heart failure while being treated with PLD. There were no treatment interruptions or discontinuations due to cardiac toxicity. Conclusion: Cumulative doses of PLD ≧400 mg/m2 are not associated with clinically evident cardiac toxicity in gynecologic oncology patients.
Hypertrophy in Mesenchymal Stem Cell Chondrogenesis: Effect of TGF-β Isoforms and Chondrogenic Conditioning
Authors: Mueller Michael B. , Fischer Maria , Zellner Johannes , Berner Arne , Dienstknecht Thomas , Prantl Lukas , Kujat Richard , Nerlich Michael , Tuan Rocky S. , Angele Peter
Published: April 2010

Induction of chondrogenesis in mesenchymal stem cells (MSCs) with TGF-β leads to a hypertrophic phenotype. The hypertrophic maturation of the chondrocytes is dependent on the timed removal of TGF-β and sensitive to hypertrophy-promoting agents in vitro. In this study, we have investigated whether TGF-β3, which has been shown to be more prochondrogenic compared to TGF-β1, similarly enhances terminal differentiation in an in vitro hypertrophy model of chondrogenically differentiating MSCs. In addition, we tested the impact of the time of chondrogenic conditioning on the enhancement of hypertrophy. MSCs were chondrogenically differentiated in pellet culture in medium containing TGF-β1 or TGF-β3. After 2 or 4 weeks, chondrogenic medium was switched to hypertrophy-inducing medium for 2 weeks. Aggregates were analyzed histologically and biochemically on days 14, 28 and 42. The switch to hypertrophy medium after 14 days induced hypertrophic cell morphology and significant increase in alkaline phosphatase activity compared to the chondrogenesis only control using both TGF-β1 and TGF-β3. After 28 days predifferentiation, differences between hypertrophic and control groups diminished compared to 14 days predifferentiation. In conclusion, chondrogenic conditioning with both TGF-β isoforms similarly induced hypertrophy in our experiment and allowed the enhancement of the hypertrophic chondrocyte phenotype by hypertrophic medium. Enhancement of hypertrophy was seen more clearly after the shorter chondrogenic conditioning. Therefore, to utilize this experimental model as a tool to study hypertrophy in MSC chondrogenesis, a predifferentiation period of 14 days is recommended.