bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Si3N4/SiO2/Si and SiO2/Si3N4/Si Multilayers by O and N K-Edge X-ray Absorption Spectroscopy
Authors: Lee Youn-Seoung , Lee Won-Jun , Kang Sung-Kyu , Rha Sa-Kyun
Published: August 2010

We deposited interpoly-stacked dielectric films with Si3N4/SiO2/Si (ON) and SiO2/Si3N4/Si (NO) structures by the atomic layer deposition method. The multilayer structure of these films with the interfaces was investigated by O and N K-edge X-ray absorption spectroscopy, nondestructive method. The electrical properties of the films were also estimated in comparison with those of Si3N4 and SiO2 single layers. A few defects existed in the interface layer of both NO and ON structures. In particular, the oxynitride interface layer was detected in the NO multilayer. The ON stacked structure had a lower leakage current and higher breakdown voltage than the NO structure and had very similar electrical properties to those of the SiO2 single layer.
Pulsed Supermagnetron Plasma Chemical Vapor Deposition of Hydrogenated Amorphous Carbon Nitride Films
Authors: Kinoshita Haruhisa , Yamaguchi Atsushi
Published: August 2010

Pulsed supermagnetron plasma was applied to the deposition of hydrogenated amorphous carbon nitride (a-CN
x
:H) films. The range of upper/lower electrode rf powers (UPRF/LORF) was selected as 0–800/0–800 W, and films were deposited using i-C4H10/N2 plasma. Phase-controlled rf power (13.56 MHz) was modulated by a 2.5 kHz pulse frequency. The range of duty ratios for the pulsed rf power range was selected as 12.5–100%. With a decrease in duty ratio, the wafer temperature decreased as the pulsed plasma-discharge time decreased. The optical band gap decreased slightly with an increase in duty ratio. At a duty ratio of 12.5%, the optical band gap decreased significantly with an increase in LORF. The nitrogen atom concentrations of the films were less than 9%, and hard a-CN
x
:H films of approximately 35 GPa were obtained at a LORF of 50 W, independent of UPRF.
Time-Resolved Spectroscopic Observation of Deposition Processes of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films by Using a Coaxial Arc Plasma Gun
Authors: Hanada Kenji , Yoshitake Tsuyoshi , Nishiyama Takashi , Nagayama Kunihito
Published: August 2010

The deposition of ultrananocrystalline diamond (UNCD)/amorphous carbon composite films using a coaxial arc plasma gun in vacuum and, for comparison, in a 53.3 Pa hydrogen atmosphere was spectroscopically observed using a high-speed camera equipped with narrow-band-pass filters. UNCD crystallites with diameters of approximately 1.6 nm were formed even in vacuum. These extremely small crystallites imply that the formation is predominantly due to nucleation without the subsequent growth. Even in vacuum, emissions from C+ ions, C atoms, and C2 dimers lasted for approximately 100 µs, although the emission lifetimes of these species are generally 10 ns. We consider that the nucleation is due to the supersaturated environment containing excited carbon species with large number densities.
Phosphorescent Organic Light-Emitting Diodes with Simplified Device Architecture
Authors: Seo Ji Hyun , Kim Hoe Min , Choi Eun Young , Choi Dae Hyuk , Park Jung Hwan , Yoo Han Seong , Kang Hyun Ju , Lee Kum Hee , Yoon Seung Soo , Kim Young Kwan
Published: August 2010

We demonstrated that single-layered red phosphorescent organic light-emitting diodes (OLEDs) can have high a efficiency without carrier transport and injection layers. This high efficiency is caused by the direct injection of carriers from electrodes into a dopant, bis(2-phenylquinoline) iridium(III) (acetylacetonate) [Ir(ppy)2(acac)]. This mechanism is proved by analyzing the single-layered devices with various hosts, 4,4'-N,N'-dicarbazole-biphenyl (CBP), 9-phenyl-3-[4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl]-9H-carbazole (LPGH 114), 9-(naphthalen-2-yl)-3-[4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl]-9H-carbazole (LPGH 124), and 9-phenyl-3,6-bis[4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl]-9H-carbazole (LPGH 153). Among the devices, the single-layered device with LPGH 153 shows a luminous efficiency, a power efficiency, and a quantum efficiency of 9.3 cd/A, 5.2 lm/W, and 6.2%, respectively. The single-layered device with CBP was compared with a multilayered device with CBP. As a result, the single-layered device shows a reduced operating voltage, an enhanced roll-off efficiency, and a pure emitting color in comparison with the multilayered device owing to the direct injection of carriers into a dopant and the suppression of exciplex formation.
Melt Molding of Uniaxially-Oriented Crystal Domains onto a Substrate
Authors: Yamao Takeshi , Juri Keiichiro , Sakaguchi Takuya , Sakurai Yoichi , Kuriki Hirofumi , Kamoi Akira , Hotta Shu
Published: August 2010

We have fabricated semiconducting oligomer films composed of uniaxially-oriented crystal domains by melt molding. It is highly important to generate a temperature gradient in the lateral direction parallel to the substrate on which the said oligomer films are fabricated. As a result, the melted oligomer layer starts to solidify from parts of lower temperatures to end up as a uniaxially aligned film. The uniaxial alignment is further promoted by slowly cooling that oligomer layer. In the present studies, the temperature gradient was set at ∼0.06–0.4 °C/mm. From the polarizing microscope observations, we confirm that within this range the temperature gradient efficiently produces the uniaxial orientation. This method has been applied to fabricating organic field-effect transistors. Those devices show an effective modulation of the drain current with varying gate voltage.
Treatment of Second-Order Structures of Proteins Using Oxygen Radio Frequency Plasma
Authors: Hayashi Nobuya , Nakahigashi Akari , Liu Hao , Goto Masaaki
Published: August 2010

Decomposition characteristics of second-order structures of proteins are determined using an oxygen radio frequency (RF) plasma sterilizer in order to prevent infectious proteins from contaminating medical equipment in hospitals. The removal of casein protein as a test protein with a concentration of 50 mg/cm2 on the plane substrate requires approximately 8 h when singlet atomic oxygen is irradiated. The peak intensity of Fourier transform infrared spectroscopy (FTIR) spectra of the β-sheet structures decreases at approximately the same rate as those of the α-helix and first-order structures of proteins. Active oxygen has a sufficient oxidation energy to dissociate hydrogen bonds within the β-sheet structure.
Improvement of Thickness Uniformity of Silicon on Insulator Layer by Numerically Controlled Sacrificial Oxidation Using Atmospheric-Pressure Plasma with Electrode Array System
Authors: Kamisaka Shohei , Yoshinaga Keinosuke , Sano Yasuhisa , Mimura Hidekazu , Matsuyama Satoshi , Yamauchi Kazuto
Published: August 2010

Recently, silicon-on-insulator (SOI) metal–oxide–semiconductor field-effect transistors (MOSFETs) have attracted great interest from manufacturers of semiconductor devices because of their excellent electrical characteristics. According to International Technology Roadmap for Semiconductors 2007, a very uniform surface Si layer will be required in a few years; however, no production method has been identified. To achieve the required uniformity in surface Si layer thickness, a new method of numerically controlled sacrificial oxidation using atmospheric-pressure plasma was developed. This paper demonstrates a new electrode array system developed for rapid processing. A very uniform oxide with a peak-to-valley (PV) of 0.13 nm was obtained; the relationship of oxide thickness versus oxidation time is shown.
Effects of Temperature and Humidity Treatment Conditions on the Interfacial Adhesion Energy between the Electroless-Plated Ni and Polyimide
Authors: Park Sung-Cheol , Min Kyoung-Jin , Lee Kyu Hwan , Jeong Yongsoo , Park Young-Bae
Published: August 2010

The effect of temperature/humidity treatment conditions on the interfacial adhesion energy between an electroless-plated Ni film and a polyimide substrate was evaluated by using a 180° peel test. The measured peel strength values decrease from 506.1 ±18.6 to 231.9 ±33.3 J/m2 due to the temperature/humidity treatment at 85 °C/85% relative humidity for 1000 h. X-ray photoelectron spectroscopy analysis of the peeled surfaces indicates that peeling occurs cohesively inside of the polyimide; this is related to both the decrease in the interfacial adhesion energy and the polyimide degradation when small quantities of the remaining alkali ions react with the polyimide's functional groups during the temperature/humidity treatment.
Structure of an Actuator and Reflective Coat for the Deformable Mirror
Authors: Aoki Sunao , Yamada Masahiro
Published: August 2010

By using conventional micro-electro-mechanical system (MEMS) processes, we have successfully developed a highly accurate and easily controllable deformable mirror with a simple structure. Our deformable mirror is driven by a single actuator different from a conventional deformable mirror of multi-actuator type. The deformed shape is controlled by optimizing the strength distribution on the reverse side of the mirror. Furthermore, we have obtained a reflective film of low-stress which was previously a challenge. In addition, we will discuss the characteristics of the deformable mirror, particularly its internal structure and frequency response.
Development of Asymmetric Twin Objective Lens Actuator Using Integrated Design Method
Authors: Woo Jung-Hyun , Park No-Cheol , Park Young-Pil , Park Kyoung-Su , Oh Young-Se , Kim Ki-Beom
Published: August 2010

We propose an asymmetric twin objective lens actuator for a slim Blu-ray (BD) drive, which is compatible with a compact disc (CD) and a digital versatile disc (DVD). A special electromagnetic (EM) circuit was designed to generate high driving forces in the three-axis direction and an integrated design method was applied to perform multiphysics modeling and multiphysics analysis simultaneously. The design of experiment (DOE) and optimization were carried out to improve dynamic characteristics of the proposed actuator. Consequently, the proposed actuator was evaluated and verified by experiment.
Amplitude and Phase Measurements of Highly Focused Light in Optical Data Storage Systems
Authors: Kim Myun-Sik , Scharf Toralf , Herzig Hans Peter
Published: August 2010

We propose a new measurement technique to investigate the highly focused light used in optical data storage systems named immersion high resolution interference microscopy (HRIM). This system allows three-dimensional (3D) measurements of the amplitude and phase of light fields in a static scheme. In contrast to scanning techniques, HRIM allows the nondestructive investigation penetrating through the optical disc. We investigated the focusing of light in high-definition digital versatile disc (HD DVD) systems. The experimental spot sizes agree well with the theory in intensity measurements. The measured phase distributions resemble the wavefront propagation of aberration-free converging light beams. The observed phase singularity positions near the focal plane demonstrate the super-resolution capability of such measurements and give access to details of the Airy pattern. Our results prove the applicability of studying highly focused beams in advanced optical systems and its use to clarify storage mechanisms for future generations of optical memories.
Performance Evaluation of the Reed Solomon and Low Density Parity Check Codes for Blu-ray Disk Channels
Authors: Kong Gyuyeol , Choi Sooyong
Published: August 2010

In this paper, we evaluate the performances of the Reed–Solomon (RS) and low density parity check (LDPC) codes in order to propose an efficient coding system for the outer code in high density optical recording channels. Hard decision decoding (HDD) RS code, iterative soft decision decoding (SDD) RS code or LDPC code is used as the outer code and LDPC code is used as the inner code. We compare the bit error rate (BER) performance of each coding system for various code rates, code lengths and burst errors. Simulation results show that the LDPC code has a better BER performance than the HDD RS and iterative SDD RS codes as the outer code in high density optical channels. Therefore, the LDPC code could be more attractive as the outer code than the RS code in high density optical channels.
Modified Two-Dimensional Soft Output Viterbi Algorithm for Holographic Data Storage
Authors: Kim Jinyoung , Lee Jaejin
Published: August 2010

We propose an alternate two-dimensional soft output Viterbi algorithm (2D SOVA) for holographic data storage. The proposed 2D SOVA uses a one-dimensional (1D) SOVA for both the horizontal and vertical directions. The 1D SOVA detects each direction with extrinsic information on the other direction's 1D SOVA. This proposed 2D SOVA has a better performance than a conventional 2D SOVA in terms of output bit error rate.
Error Correcting 4/6 Modulation Codes for Holographic Data Storage
Authors: Kim Jinyoung , Wee Jae-Kyung , Lee Jaejin
Published: August 2010

We introduce error correcting 4/6 modulation codes for holographic data storage. Above all, the merit of the proposed modulation codes is that their trellis structure allows error correcting capability. The proposed codes also do not have any fatal (i.e., isolated pixels) two-dimensional intersymbol interference (2D ISI) patterns. The decoding scheme uses the Viterbi algorithm. As a result, the proposed codes have better performance than the conventional 6/8 and 4/6 modulation codes overall.
Tone-Controllable Codes for Holographic Data Storage System
Authors: Park Donghyuk , Yoo Myungsik , Lee Jaejin
Published: August 2010

The first merit of the holographic data storage (HDS) system is its high storage capacity. In practice, it is well known that the total capacity for the storage medium depends on the appropriate ratio of ON and OFF pixels within data pages. Therefore, we propose a modulation code that can control the ratio of ON and OFF pixels. We refer to this code as “tone-controllable code”. In this paper, we introduce the encoding/decoding rules and simulate the bit error rate (BER) performance of the tone-controllable codes having various ratios of ON and OFF pixels.
Reducing Axial Run-Out in a Flexible Optical Disk by Restricting Airflow to the Aerodynamic Stabilizer
Authors: Kajiyama Takeshi , Koide Daiichi , Tokumaru Haruki , Takano Yoshimichi , Onagi Nobuaki , Aman Yasutomo
Published: August 2010

Flexible optical disks (FODs) can be rotated at 15,000 rpm and have the capability of recording at 250 Mbps, the rate necessary for a high definition video recording system (HD-D5). Although the conventional stabilization system can suppress the axial run-out of FODs to approximately 1/10 (≤10 µm) of that of current optical disks, FODs rotating at 15,000 rpm must be set close to the stabilizer within about 100 µm. Because of this severe positioning constraint at high-speed rotation, high accuracy of assembly and positioning are required in the drive system, and the mechanical margin of the setting is very narrow. To overcome this problem, we developed a new stabilizing method that can suppress the axial run-out while keeping a wide clearance margin between the disk and stabilizer by restricting airflow to the stabilizer.
Passive-Damping of the Axial Run-Out for High Speed Rotating Flexible Optical Disk Using the Idea of Damping Orifice
Authors: Gad Abdelrasoul M. M. , Rhim Yoon Chul
Published: August 2010

In the present work, the idea of damping orifice is applied so as to reduce the axial run-out of a high speed rotating flexible optical disk. A track or more of rectangular-edge orifices is inscribed in a rigid flat stabilizer near the outer region of the disk that exhibits large vibration amplitudes. The effects of the orifice geometry, number of orifices per track, and the number of tracks are investigated experimentally. The results from this study show that the introduced new design of the stabilizer can reduce the axial run-out of the disk at 10,000 rpm to within 10 µm over its entire span using two tracks of damping orifices near the disk rim. The study proved that the introduced orifices in the flat stabilizer effectively enhance the damping capability of the air-film to dissipate the vibration energy of the rotating disk.
Improvement of Shock Resistance for Solid Immersion Lens-Based Near Field Recording System Using Air-Bearing Surface
Authors: Lee Yonghyun , Lee Yong-Eun , Lee Sang Jik , Kim Ki-Hoon , Kim Seokhwan , Park No-Cheol , Park Young-Pil , Park Kyoung-Su
Published: August 2010

A solid immersion lens (SIL)-based near-field recording (NFR) device is regarded as the next-generation optical storage device that can achieve an areal density of more than 100 Gbyte/in.2. However, the NFR system is very weak to external shock because of the extremely small gap between the SIL and the disc. To solve this problem, we proposed a new method of using an air-bearing surface (ABS) to avoid collision between the SIL and the disc, and investigated the effect of the ABS on shock resistance in our previous study. In our current study, we optimize an initial ABS model using the results of our previous study and achieve an optimal ABS model with an improved shock resistance. We also verify the improvement of shock resistance for the optimal ABS model by finite element (FE) analysis, by applying the ABS model to a gap servo control system, and by experimental shock testing.
Improved Antishock Air-Gap Control Algorithm with Acceleration Feedforward Control for High-Numerical Aperture Near-Field Storage System Using Solid Immersion Lens
Authors: Kim Jung-Gon , Shin Won-Ho , Hwang Hyun-Woo , Jeong Jun , Park Kyoung-Su , Park No-Cheol , Yang Hyunseok , Park Young-Pil , Park Jin Moo , Son Do Hyeon , Seo Jeong Kyo , Choi In Ho
Published: August 2010

A near-field storage system using a solid immersion lens (SIL) has been studied as a high-density optical disc drive system. The major goal of this research is to improve the robustness of the air-gap controller for a SIL-based near-field recording (NFR) system against dynamic disturbances, such as external shocks. The servo system is essential in near-field (NF) technology because the nanogap distance between the SIL and the disc is 50 nm or less. Also, the air-gap distance must be maintained without collision between the SIL and the disc to detect a stable gap error and read-out signals when an external shock is applied. Therefore, we propose an improved air-gap control algorithm using only an acceleration feedforward controller (AFC) to maintain the air-gap distance without contact for a 4.48 G at 10 ms shock. Thus, the antishock control performance for the SIL-based NF storage system in the presence of external shocks is markedly improved. Furthermore, to enhance the performance of the antishock air-gap control, we use the AFC with a double disturbance observer and a dead-zone nonlinear controller. As a result, the air-gap distance is maintained without contact for a 6.56 G@10 ms shock.
Write Strategy Optimization Method with Two-Step Search for Blu-ray Disc Recording
Authors: Takeshita Nobuo , Kanatake Yusuke , Kishigami Tomo , Ikuta Koichi
Published: August 2010

A new write strategy (WS) optimization method with a two-step search process for Blu-ray Disc (BD) recording is developed to shorten the optimization time. This method is realized by the WS optimization system, which is constructed with an optical pickup, a disc tester, and the WS optimization algorithm. The optimization is executed according to the two-step search process along the mathematical axis, which is experimentally derived from the sample WS parameters. As the experimental result, the optimization time is reduced by nearly two-thirds from that achieved using the conventional method performed by the experts. All the jitter values of the playback signal derived from the recorded marks are smaller than the 7% target value and the effectiveness of this new method is experimentally confirmed.
Dual-Wavelength Sensitized Photopolymer for Holographic Data Storage
Authors: Tao Shiquan , Zhao Yuxia , Wan Yuhong , Zhai Qianli , Liu Pengfei , Wang Dayong , Wu Feipeng
Published: August 2010

Novel photopolymers for holographic storage were investigated by combining acrylate monomers and/or vinyl monomers as recording media and liquid epoxy resins plus an amine harder as binder. In order to improve the holographic performances of the material at blue-green wavelength band two novel dyes were used as sensitizer. The methods of evaluating the holographic performances of the material, including the shrinkage and noise characteristics, are described in detail. Preliminary experiments show that samples with optimized composite have good holographic performances, and it is possible to record dual-wavelength hologram simultaneously in this photopolymer by sharing the same optical system, thus the storage density and data rate can be doubly increased.
Enhancement of Repositioning Tolerance by Directionally Controlled Shift Selectivity of Speckle-Multiplexed Holograms
Authors: Bunsen Masatoshi , Fukuchi Seiji , Takahashi Shuji , Furuta Hirosuke , Okamoto Atsushi
Published: August 2010

A method for directional control of shift selectivities of speckle-multiplexed holograms with a diffuser whose diffusion angle varies with the diffusion direction is proposed to enhance the tolerance of recorded holograms to repositioning error in holographic storage. The directional dependence and controllability of shift selectivities of holograms are experimentally investigated using various diffusers. By retrieving 50 speckle-multiplexed holograms with deliberate deviations from the original recording position and by measuring bit error rate, it is also confirmed that the tolerance to repositioning error is improved.
Speckle-Multiplexed Hologram Using Speckle Filter with a Polymer-Dispersed Liquid Crystal
Authors: Sekiguchi Toru , Katsumata Akiyoshi , Tanaka Hiroaki , Wenjun Hu , Honma Satoshi
Published: August 2010

It is known well that speckle referencing enhances the shift selectivity of holograms. In this paper, the scheme of using speckle patterns produced by a filter with a polymer-dispersed liquid crystal is applied to multiplexing holograms. The speckle patterns can be reconfigured by applying an electric field to the filter. The experiment confirmed the feasibility of a hybrid scheme with shift multiplexing and speckle multiplexing.
Recording Characteristics of 10-Layer Recordable Optical Disc and a Prospect for Over 500 Gbyte Recording
Authors: Kikukawa Takashi , Inoue Motohiro , Mishima Koji , Ushida Tomoki
Published: August 2010

A 10-layer recordable optical disc with an inorganic recording material, Bi–Ge–O, was fabricated and the recording characteristics were measured using a Blu-ray Disc-based apparatus with a wavelength of 405 nm and a numerical aperture of 0.85. Practical signal quality was obtained from all the layers at densities of 25 and 32 Gbyte per layer. A 16-layer recordable optical disc was also fabricated and measured. Practical signal quality was also obtained from both the 1st layer and the 16th layer.
Thermal Recording for High-Density Optical Disc Mastering
Authors: Yamaoka Nobuki , Murakami Shigenori , Sugawara Yukihiro , Ohshima Seiro , Takishita Toshihiko , Yokogawa Fumihiko
Published: August 2010

Thermal recording using a dielectric as a recording material was examined to make a high-density optical disc master. We confirmed that a pit of 53 nm length was able to be recorded with a laser of 405 nm wavelength. As a result we could make a master with a 200 gigabyte (GB) data capacity with a conventional laser beam recorder (LBR). A 100 GB disc made by the same method was able to be read with a tester equipped with a solid immersion lens (SIL) and the measured jitter value was 9.9%.
Scanning Probe Microscopy for Identifying the Component Materials of a Nanostripe Structure
Authors: Mizuno Akira , Ando Yasuhisa
Published: August 2010

The authors prepared a nanostripe structure in which two types of metal are arranged alternately, and successfully identified the component materials using scanning probe microscopy (SPM) to measure the lateral force distribution image. The nanostripe structure was prepared using a new method developed by the authors and joint development members. The lateral force distribution image was measured in both friction force microscopy (FFM) and lateral modulation friction force microscopy (LM-FFM) modes. In FFM mode, the effect of slope angle appeared in the lateral force distribution image; therefore, no difference in the type of material was observed. On the other hand, in LM-FFM mode, the effect of surface curvature was observed in the lateral force distribution image. A higher friction force on chromium than on gold was identified, enabling material identification.
Prism-Coupled Scanning Tunneling Microscope Light Emission Spectroscopy of Au Film Covered with Self-Assembled Alkanethiol Monolayer
Authors: Ahamed Jamal Uddin , Sanbongi Tomonori , Katano Satoshi , Uehara Yoichi
Published: August 2010

We have investigated scanning tunneling microscope (STM) light emission from bare and alkanethiol self-assembled monolayer (SAM)-covered Au films in the Kretschmann geometry. The films were deposited on the flat bottom of a hemispherical prism, and the STM light emissions from the tip–sample gap into the vacuum (tip-side emission) and into the prism (prism-side emission) were measured. The prism-side emission was much stronger than the tip-side emission for the bare Au film. Theoretical analysis revealed that this enhancement of emission intensity is caused by the fact that surface plasmon polaritons (SPPs) localized at the Au surface become radiative on the prism side. This geometry was applied to the investigations of STM light emission from the Au film covered with an alkanethiol SAM. The prism-side emission was successfully detected by virtue of the enhancement of STM light emission.
Investigations of Local Electrical Properties of Pentacene Thin Films by Dual-Probe Atomic Force Microscopy
Authors: Hirose Masaharu , Tsunemi Eika , Kobayashi Kei , Yamada Hirofumi , Matsushige Kazumi
Published: August 2010

We performed local electrical transport measurement on single grains of a pentacene thin film using a lab-built dual-probe atomic force microscopy (DP-AFM) system. We brought two conducting cantilever tips in contact with a single grain and successfully measured the p-type field-effect characteristics. Moreover, we investigated the effect of contact resistance on the measured characteristics by performing a series of transport measurements while varying tip distance. The contact resistance and hole mobility of the channel region were estimated as 3.1 GΩ and 2.7×10-2 cm2 V-1 s-1, respectively. The results demonstrate the applicability of the DP-AFM system to the nanometer-scale transport measurement of molecules.
Low-Temperature Scanning Tunneling Microscopy Investigation of Tris(phthalocyaninato)yttrium Triple-Decker Molecules Deposited on Au(111)
Authors: Isshiki Hironari , Liu Jie , Katoh Keiichi , Yamashita Masahiro , Miyasaka Hitoshi , Breedlove Brian K. , Takaishi Shinya , Komeda Tadahiro
Published: August 2010

We have executed scanning tunneling microscopy (STM) observation of triple-decker Y2Pc3 molecules deposited on a Au(111) surface. It is shown that the triple-decker phthalocyanine molecule, tris(phthalocyaninato)yttrium, can be successfully transferred to the Au(111) surface by a sublimation method under an ultra high vacuum condition. A monolayer film of Y2Pc3 was observed with a height of ∼0.55 nm from the bare Au(111) surface. The molecules were adsorbed with a flat-lying configuration and a pseudosquare lattice was formed. We propose a temporal model of the lattice with two unit vectors a and b, where a is parallel to the [110] direction with a length of 5a [a is the nearest-neighbor distance of the Au(111)] and b is parallel to the [112] direction with a length of 3√3a. Inside each molecule, eight-lobe bright protrusions were observed in occupied-state images, which correspond to the high-density-of-states (DOS) area on both sides of the four phenyl rings in the top phthalocyanine (Pc). Scanning tunneling spectroscopy (STS) observation showed that the HOMO and LUMO levels are at the ligand position and the metal-center position, indicating a small contribution of the metal Y to the DOS of the top layer.
Multiple mechanisms limit the accumulation of unesterified cholesterol in the small intestine of mice deficient in both ACAT2 and ABCA1
Authors: Turley Stephen D. , Valasek Mark A. , Repa Joyce J. , Dietschy John M.
Published: August 2010

Cholesterol homeostasis in the enterocyte is regulated by the interplay of multiple genes that ultimately determines the net amount of cholesterol reaching the circulation from the small intestine. The effect of deleting these genes, particularly acyl CoA:cholesterol acyl transferase 2 (ACAT2), on cholesterol absorption and fecal sterol excretion is well documented. We also know that the intestinal mRNA level for adenosine triphosphate-binding cassette transporter A1 (ABCA1) increases in Acat2−/−mice. However, none of these studies has specifically addressed how ACAT2 deficiency impacts the relative proportions of esterified and unesterified cholesterol (UC) in the enterocyte and whether the concurrent loss of ABCA1 might result in a marked buildup of UC. Therefore, the present studies measured the expression of numerous genes and related metabolic parameters in the intestine and liver of ACAT2-deficient mice fed diets containing either added cholesterol or ezetimibe, a selective sterol absorption inhibitor. Cholesterol feeding raised the concentration of UC in the small intestine, and this was accompanied by a significant reduction in the relative mRNA level for Niemann-Pick C1-like 1 (NPC1L1) and an increase in the mRNA level for both ABCA1 and ABCG5/8. All these changes were reversed by ezetimibe. When mice deficient in both ACAT2 and ABCA1 were fed a high-cholesterol diet, the increase in intestinal UC levels was no greater than it was in mice lacking only ACAT2. This resulted from a combination of compensatory mechanisms including diminished NPC1L1-mediated cholesterol uptake, increased cholesterol efflux via ABCG5/8, and possibly rapid cell turnover.
Effect of aging on gastric mucosal defense mechanisms: ROS, apoptosis, angiogenesis, and sensory neurons
Authors: Kang Jung Mook , Kim Nayoung , Kim Joo-Hyon , Oh Euichaul , Lee Bong-Yong , Lee Byoung Hwan , Shin Cheol Min , Park Ji Hyun , Lee Mi Kyoung , Nam Ryoung Hee , Lee Hee Eun , Lee Hye Seung , Kim Joo Sung , Jung Hyun Chae , Song In Sung
Published: August 2010

Aging changes in the stomach lead to a decreased capacity for tissue repair in response to gastric acid. The aim of this study was to determine the mechanism associated with the increased susceptibility to injury of aging mucosa including reactive oxygen species ( 5 ), apoptosis, angiogenesis, and sensory neuron activity. Fischer 344 rats at four different ages (6, 31, 74 wk, and 2 yr of age) were studied. The connective tissue indicators [salt-soluble collagen and sulfated glycosaminoglycan (sGAG)], lipid hydroperoxide (LPO), myeloperoxidase (MPO), and hexosamine were assessed. We also evaluated the expression of early growth response-1 (Egr-1), phosphatase and tension homologue deleted on chromosome 10 (PTEN), caspase-9 (index of apoptosis), VEGF (index of angiogenesis), calcitonin gene-related peptide (CGRP, index of sensory neurons), and neuronal nitric oxide synthase (nNOS). The histological connective tissue area in the lower part of rat gastric mucosa increased with aging, with increase of salt-soluble collagen and sGAG. LPO and MPO in old rats were significantly greater than in the young rats, whereas hexosamine was significantly reduced. The old gastric mucosa had increased expression of Egr-1, PTEN, and caspase-9, whereas the VEGF, CGRP, and nNOS expression were significantly reduced. These results indicate that the lower part of rat gastric mucosa was found to be replaced by connective tissue with accumulation of oxidative products with aging. In addition, impairment of apoptosis, angiogenesis, and sensory neuron activity via the activation of Egr-1 and PTEN might increase the susceptibility of gastric mucosa to injury during aging.
Betaine improves nonalcoholic fatty liver and associated hepatic insulin resistance: a potential mechanism for hepatoprotection by betaine
Authors: Kathirvel Elango , Morgan Kengathevy , Nandgiri Ganesh , Sandoval Brian C. , Caudill Marie A. , Bottiglieri Teodoro , French Samuel W. , Morgan Timothy R.
Published: August 2010

Nonalcoholic fatty liver (NAFL) is a common liver disease, associated with insulin resistance. Betaine has been tested as a treatment for NAFL in animal models and in small clinical trials, with mixed results. The present study aims to determine whether betaine treatment would prevent or treat NAFL in mice and to understand how betaine reverses hepatic insulin resistance. Male mice were fed a moderate high-fat diet (mHF) containing 20% of calories from fat for 7 (mHF) or 8 (mHF8) mo without betaine, with betaine (mHFB), or with betaine for the last 6 wk (mHF8B). Control mice were fed standard chow containing 9% of calories from fat for 7 mo (SF) or 8 mo (SF8). HepG2 cells were made insulin resistant and then studied with or without betaine. mHF mice had higher body weight, fasting glucose, insulin, and triglycerides and greater hepatic fat than SF mice. Betaine reduced fasting glucose, insulin, triglycerides, and hepatic fat. In the mHF8B group, betaine treatment significantly improved insulin resistance and hepatic steatosis. Hepatic betaine content significantly decreased in mHF and increased significantly in mHFB. Betaine treatment reversed the inhibition of hepatic insulin signaling in mHF and in insulin-resistant HepG2 cells, including normalization of insulin receptor substrate 1 (IRS1) phosphorylation and of downstream signaling pathways for gluconeogenesis and glycogen synthesis. Betaine treatment prevents and treats fatty liver in a moderate high-dietary-fat model of NAFL in mice. Betaine also reverses hepatic insulin resistance in part by increasing the activation of IRS1, with resultant improvement in downstream signaling pathways.
Energetics of stress production in isolated cardiac trabeculae from the rat
Authors: Han June-Chiew , Taberner Andrew J. , Nielsen Poul M. F. , Kirton Robert S. , Ward Marie-Louise , Loiselle Denis S.
Published: August 2010

The heat liberated upon stress production in isolated cardiac muscle provides insights into the complex thermodynamic processes underlying mechanical contraction. To that end, we simultaneously measured the heat and stress (force per cross-sectional area) production of cardiac trabeculae from rats using a flow-through micromechanocalorimeter. In a flowing stream of O2-equilibrated Tyrode solution (∼22°C), the stress and heat production of actively contracting trabeculae were varied by 1) altering stimulus frequency (0.2–4 Hz) at optimal muscle length ( Lo), 2) reducing muscle length below Lo at 0.2 and 2 Hz, and 3) changing extracellular Ca2+ concentrations ([Ca2+]o; 1 and 2 mM). Linear regression lines were adequate to fit the active heat-stress data. The active heat-stress relationships were independent of stimulus frequency and muscle length but were dependent on [Ca2+]o, having greater intercepts at 2 mM [Ca2+]o than at 1 mM [Ca2+]o (3.5 and 2.0 kJ·m−3·twitch−1, respectively). The slopes among the heat-stress relationships did not differ. At the highest experimental stimulus frequency, pronounced elevation of diastolic Ca2+ resulted in incomplete twitch relaxation. The resulting increase of diastolic stress, which occurred with negligible metabolic energy expenditure, subsequently diminished due to the time-dependent loss of myofilament Ca2+-sensitivity.
Kallistatin attenuates endothelial apoptosis through inhibition of oxidative stress and activation of Akt-eNOS signaling
Authors: Shen Bo , Gao Lin , Hsu Yi-Te , Bledsoe Grant , Hagiwara Makato , Chao Lee , Chao Julie
Published: August 2010

Kallistatin is a regulator of vascular homeostasis capable of controlling a wide spectrum of biological actions in the cardiovascular and renal systems. We previously reported that kallistatin inhibited intracellular reactive oxygen species formation in cultured cardiac and renal cells. The present study was aimed to investigate the role and mechanisms of kallistatin in protection against oxidative stress-induced vascular injury and endothelial cell apoptosis. We found that kallistatin gene delivery significantly attenuated aortic superoxide formation and glomerular capillary loss in hypertensive DOCA-salt rats. In cultured endothelial cells, kallistatin suppressed TNF-α-induced cellular apoptosis, and the effect was blocked by the pharmacological inhibition of phosphatidylinositol 3-kinase and nitric oxide synthase (NOS) and by the knockdown of endothelial NOS (eNOS) expression. The transduction of endothelial cells with adenovirus expressing dominant-negative Akt abolished the protective effect of kallistatin on endothelial apoptosis and caspase activity. In addition, kallistatin inhibited TNF-α-induced reactive oxygen species formation and NADPH oxidase activity, and these effects were attenuated by phosphatidylinositol 3-kinase and NOS inhibition. Kallistatin also prevented the induction of Bim protein and mRNA expression by oxidative stress. Moreover, the downregulation of forkhead box O 1 (FOXO1) and Bim expression suppressed TNF-α-mediated endothelial cell death. Furthermore, the antiapoptotic actions of kallistatin were accompanied by Akt-mediated FOXO1 and eNOS phosphorylation, as well as increased NOS activity. These findings indicate a novel role of kallistatin in the protection against vascular injury and oxidative stress-induced endothelial apoptosis via the activation of Akt-dependent eNOS signaling.
Effect of metabolic acidosis on neonatal proximal tubule acidification
Authors: Twombley Katherine , Gattineni Jyothsna , Bobulescu Ion Alexandru , Dwarakanath Vangipuram , Baum Michel
Published: August 2010

The serum bicarbonate in neonates is lower than adults due in large part to a lower rate of proximal tubule acidification. It is unclear if the neonatal proximal tubule is functioning at maximal capacity or if the proximal tubule can respond to metabolic acidosis as has been described in adult proximal tubules. We find that neonatal mouse brush-border membranes have a lower Na+/H+exchanger (NHE) 3 protein abundance (neonate 0.11 ± 0.05 vs. adult 0.64 ± 0.07; P < 0.05) and a higher NHE8 protein abundance (neonate 1.0 ± 0.01 vs. adult 0.13 ± 0.09; P < 0.001) compared with adults. To examine if neonates can adapt to acidosis, neonatal mice were gavaged with either acid or vehicle for 4 days, resulting in a drop in serum bicarbonate from 19.5 ± 1.0 to 8.9 ± 0.6 meq/l ( P < 0.001). Proximal convoluted tubule Na+/H+exchanger activity (dpHi/d t) was 1.68 ± 0.19 pH units/min in control tubules and 2.49 ± 0.60 pH units/min in acidemic neonatal mice ( P < 0.05), indicating that the neonatal proximal tubule can respond to metabolic acidosis with an increase in Na+/H+exchanger activity. Similarly, brush-border membrane vesicles from neonatal rats had an increase in Na+/H+exchanger activity with acidemia that was almost totally inhibited by 10−6M 5-( N-ethyl- n-isopropyl)-amiloride, a dose that has little effect on NHE3 but inhibits NHE8. There was a significant increase in both NHE3 (vehicle 0.35 ± 0.07 vs. acid 0.73 ± 0.07; P < 0.003) and NHE8 brush-border membrane protein abundance (vehicle 0.41 ± 0.05 vs. acid 0.73 ± 0.06; P < 0.001) in acidemic mouse neonates compared with controls. A comparable increase in NHE3 and NHE8 was found in neonatal rats with acidosis. In conclusion, the neonatal proximal tubule can adapt to metabolic acidosis with an increase in Na+/H+exchanger activity.
Fibroblast growth factor-10 signals development of von Brunn's nests in the exstrophic bladder
Authors: Eastman Rocky , Leaf Elizabeth M. , Zhang Dianzhong , True Lawrence D. , Sweet Robert M. , Seidel Kristy , Siebert Joseph R. , Grady Richard , Mitchell Michael E. , Bassuk James A.
Published: August 2010

von Brunn's nests have long been recognized as precursors of benign lesions of the urinary bladder mucosa. We report here that von Brunn's nests are especially prevalent in the exstrophic bladder, a birth defect that predisposes the patient to formation of bladder cancer. Cells of von Brunn's nest were found to coalesce into a stratified, polarized epithelium which surrounds itself with a capsule-like structure rich in types I, III, and IV collagen. Histocytochemical analysis and keratin profiling demonstrated that nested cells exhibited a phenotype similar, but not identical, to that of urothelial cells of transitional epithelium. Immunostaining and in situ hybridization analysis of exstrophic tissue demonstrated that the FGF-10 receptor is synthesized and retained by cells of von Brunn's nest. In contrast, FGF-10 is synthesized and secreted by mesenchymal fibroblasts via a paracrine pathway that targets basal epithelial cells of von Brunn's nests. Small clusters of 10pRp cells, positive for both FGF-10 and its receptor, were observed both proximal to and inside blood vessels in the lamina propria. The collective evidence points to a mechanism where von Brunn's nests develop under the control of the FGF-10 signal transduction system and suggests that 10pRp cells may be the original source of nested cells.
The abundance and activation of mTORC1 regulators in skeletal muscle of neonatal pigs are modulated by insulin, amino acids, and age
Authors: Suryawan Agus , Davis Teresa A.
Published: August 2010

Mammalian target of rapamycin complex 1 (mTORC1) signaling is crucial for the regulation of protein synthesis. Most of known mTORC1 regulators have been isolated and characterized using cell culture systems, and the physiological roles of these regulators have not been fully tested in vivo. Previously we demonstrated that the insulin (INS) and amino acid (AA)-induced activation of mTORC1 is developmentally regulated in skeletal muscle (Suryawan A et al. Am J Physiol Endocrinol Metab 293: E1597–E1605, 2007). The present study aimed to characterize in more detail the effects of the postprandial rise in INS and AA on the activation and abundance of mTORC1 regulators in muscle and how this is modified by development. Overnight fasted 6- and 26-day-old pigs were studied during 1) euinsulinemic-euglycemic-euaminoacidemic conditions (control), 2) euinsulinemic-euglycemic-hyperaminoacidemic clamps (AA), and 3) hyperinsulinemic-euglycemic-euaminoacidemic clamps (INS). INS, but not AA, enhanced the PRAS40 phosphorylation, and this effect was greater in 6- than in 26-day old pigs. Phospholipase D1 (PLD1) abundance and phosphorylation, and the association of PLD1 with Ras homolog enriched in brain (Rheb), were greater in the younger pigs. Neither INS, AA, nor age altered the abundance of Rheb, vacuolar protein sorting 34 (Vps34), or FK506-binding protein 38 (FKBP38). Although INS and AA had no effect, the abundance of ras-related GTP binding B (RagB) and the association of RagB with Raptor were greater in 6- than in 26-day-old pigs. Neither INS, AA, nor age altered AMPK-induced phosphorylation of Raptor. Our results suggest that the enhanced activation of mTORC1 in muscle of neonatal pigs is in part due to regulation by PRAS40, PLD1, and the Rag GTPases.
Phenol increases intracellular [Ca2+] during twitch contractions in intactXenopusskeletal myofibers
Authors: Nogueira Leonardo , Hogan Michael C.
Published: August 2010

Phenol is a neurolytic agent used for management of spasticity in patients with either motoneuron lesions or stroke. In addition, compounds that enhance muscle contractility (i.e., polyphenols, etc.) may affect muscle function through the phenol group. However, the effects of phenol on muscle function are unknown, and it was, therefore, the purpose of the present investigation to examine the effects of phenol on tension development and Ca2+release in intact skeletal muscle fibers. Dissected intact muscle fibers from Xenopus laevis were electrically stimulated, and cytosolic Ca2+concentration ([Ca2+]c) and tension development were recorded. During single twitches and unfused tetani, phenol significantly increased [Ca2+]cand tension without affecting myofilament Ca2+sensitivity. To investigate the phenol effects on Ca2+channel/ryanodine receptors, single fibers were treated with different concentrations of caffeine in the presence and absence of phenol. Low concentrations of phenol significantly increased the caffeine sensitivity ( P < 0.01) and reduced the caffeine concentrations necessary to produce nonstimulated contraction (contracture). However, at high phenol concentrations, caffeine did not increase tension or Ca2+release. These results suggest that phenol affects the ability of caffeine to release Ca2+through an effect on the ryanodine receptors, or on the sarcoplasmic reticulum Ca2+pump. During tetanic contractions inducing fatigue, phenol application decreased the time to fatigue. In summary, phenol increases intracellular [Ca2+] during twitch contractions in muscle fibers without altering myofilament Ca2+sensitivity and may be used as a new agent to study skeletal muscle Ca2+handling.
Changes in lung volume and diaphragm muscle activity at sleep onset in obese obstructive sleep apnea patients vs. healthy-weight controls
Authors: Stadler Daniel L. , McEvoy R. Doug , Bradley Jana , Paul Denzil , Catcheside Peter G.
Published: August 2010

Obese obstructive sleep apnea (OSA) patients potentially defend end-expiratory lung volume (EELV) during wakefulness via increased expiratory diaphragmatic activity (eEMGdia). A reduction in eEMGdiaand EELV at sleep onset could, therefore, increase upper airway collapsibility via reduced tracheal traction. The aim of this study was to establish if eEMGdiais greater in obese OSA patients vs. healthy-weight controls during wakefulness, and to compare eEMGdiaand EELV changes at sleep onset between groups as a function of stable breathing, hypopnea vs. apnea events developing within the first few breaths after sleep onset. Eight obese men with OSA and eight healthy-weight men without OSA were studied in the supine position while instrumented with an intraesophageal catheter to measure eEMGdiaand magnetometer coils to assess changes in EELV. While eEMGdiaexpressed as %maximal activity was not significantly different between groups during wakefulness, OSA patients experienced a greater fall in eEMGdiafollowing sleep onset (group × breath, P < 0.001) and a greater decrease when respiratory events accompanied sleep onsets (category × breath, P < 0.001). The decrease in EELV by the third postsleep onset breath was small (OSA, 61.4 ± 8.0 ml, P < 0.001; controls, 34.0 ± 4.2 ml, P < 0.001), with the decrease significantly greater in OSA patients over time (group × breath, P = 0.007). There was a greater decrease with more severe events (category × breath, P < 0.001), with EELV decreasing by 89.6 ± 14.2 ml ( P < 0.001) at the onset of apneas in the OSA group. These data support that diaphragm tone and EELV frequently decrease following sleep onset, with greater falls at transitions accompanied by respiratory events. In addition to decrements in upper airway dilator muscle activity, decreasing lung volume potentially contributes to an increased propensity for upper airway collapse in OSA patients at sleep onset.