bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of Cilia-Based Microfluidic Devices
Authors: Kongthon J. , Chung J.-H. , Riley J. J. , Devasia S.
Published: August 2011

This article models the dynamics of cilia-based devices (soft cantilever-type, vibrating devices that are excited by external vibrations) for mixing and manipulating liquids in microfluidic applications. The main contribution of this article is to develop a model, which shows that liquid sloshing and the added-mass effect play substantial roles in generating large-amplitude motion of the cilia. Additionally, experimental mixing results, with and without cilia, are comparatively evaluated to show more than one order-of-magnitude reduction in the mixing time with the use of cilia.
Modelling of fluorine based high density plasma for the etching of silica glasses
Authors: Lallement Ludovic , Rhallabi Ahmed , Cardinaud Christophe , Peignon Fernandez Marie Claude
Published: August 2011

An etching simulator has been developed to study the etching of commercial silica glass (Pyrex®, D263®, AF45®, and Vycor®) in a SF6/Ar inductively coupled plasma (ICP) discharge. The etching model is based on the development of the plasma kinetic model coupled to a two dimensional (2D) Monte Carlo cellular surface model to predict the etched surface morphology as a function of the operating conditions. The SF6/Ar plasma model allows us to predict the neutral and ion species fluxes, as well as the density and the temperature of electrons, as a function of the reactor operating conditions. Such output parameters are used as input parameters in both the sheath and etching models. The 2D Monte Carlo cellular model is based on the representation of both the substrate and the mask by uniform cells, which each represents a real number of sites. The preferential redeposition mechanism of the etched products on the metallic sites seems to play an important role on the formation and the propagation of the etched surface roughness. The results obtained by the model are compared with the experimental results for etching rate and roughness. A satisfactory agreement between the experimental results and the model concerning the etching rate and the etched surface morphology has been obtained for different glasses.
Formation of tetragonal or monoclinic ZrO2 coatings by oxygen plasma treatment of Zr74.7Cu19.7Nb5.6 glassy thin films
Authors: Panagiotopoulos N. T. , Kovač J. , Mozetič M. , Patsalas P. , Evangelakis G. A.
Published: August 2011

The authors report on the production of stable nanostructured tetragonal and/or monoclinic ZrO2 nanopillars achieved by means of oxygen plasma treatment of ternary Zr74.7Cu19.7Nb5.6 glassy films. The Zr-based metallic glass thin films were successfully deposited by magnetron sputtering and subsequently subjected to oxygen plasma for various exposure times. The compositions of the oxidized films were determined by Auger electron spectroscopy and X-Ray photoelectron spectroscopy depth profiling while the surface morphology was evaluated by means of atomic force microscopy and scanning electron microscopy. X-Ray diffraction was used for the structural analysis. Our results show that, depending on the length of time of oxygen plasma treatment, tetragonal and/or monoclinic ZrO2 films can be formed, the surface morphology of which exhibit nanopillar structures with an increased effective surface. These findings provide an easy and efficient way for growing ZrO2 coatings with a predefined structure suitable for protective and possibly for catalytic applications.
The Trevo device: preclinical data of a novel stroke thrombectomy device in two different animal models of arterial thrombo-occlusive disease
Authors: Nogueira Raul G , Levy Elad I , Gounis Matthew , Siddiqui Adnan H
Published: August 2011

Background

The currently available mechanical devices fail to achieve recanalization in as many as 20–40% of proximal arterial occlusion strokes.

Objective

The preclinical evaluation of the safety and efficacy of a novel thrombectomy device designed to achieve immediate flow restoration by quickly removing clot is reported.

Methods

Four confirmatory animal studies were performed with the Trevo device (Concentric Medical Inc, Mountain View, California, USA) in the swine (n=2) and canine (n=1) models of arterial thrombo-occlusive disease employing autologous thrombin generated thrombi. The angiographic response and the degree of device–clot incorporation were evaluated. High resolution flat panel three-dimensional CT was performed to further define the in vivo device–thrombus–vessel interaction. Finally, samples of three swine vessels treated with six passes of the device were explanted for histopathological analysis.

Results

A total of 16 clots of variable hardness and consistency were implanted in a variety of vascular settings, including the swine internal maxillary, lingual and forelimb arteries as well as the canine external carotid and vertebral arteries. Thrombolysis in Myocardial Infarction (TIMI) 2–3 reperfusion was achieved in all cases immediately after device deployment. All 16 clots were retrieved after one (n=15) or two (n=1) passes with the device. Histopathological analysis demonstrated severe disruption of the intima but no hemorrhage of media or adventitia.

Conclusion

The experimental data suggest that the Trevo device is highly effective at achieving immediate reperfusion of occluded arteries without causing any clinically significant disruption of vascular integrity.
A REVISED STOCHASTIC OPTIMAL VELOCITY MODEL CONSIDERING THE VELOCITY GAP WITH A PRECEDING VEHICLE
Authors: SHIGAKI KEIZO , TANIMOTO JUN , HAGISHIMA AYA
Published: August 2011

The stochastic optimal velocity (SOV) model, which is a cellular automata model, has been widely used because of its good reproducibility of the fundamental diagram, despite its simplicity. However, it has a drawback: in SOV, a vehicle that is temporarily stopped takes a long time to restart. This study proposes a revised SOV model that suppresses this particular defect; the basic concept of this model is derived from the car-following model, which considers the velocity gap between a particular vehicle and the preceding vehicle. A series of simulations identifies the model parameters and clarifies that the proposed model can reproduce the three traffic phases: free, jam, and even synchronized phases, which cannot be achieved by the conventional SOV model.
UNIVERSAL ENTROPY BOUND AND DISCRETE SPACETIME
Authors: XU YUNQI , MA BO-QIANG
Published: August 2011

Starting from the universal entropy bounds suggested by Bekenstein and Susskind and applying them to the black-body radiation situation, we get a cut-off of space Δx ≥χl P with χ≥0.1. We go further to get a cutoff of time Δt ≥χl P /c, thus, the discrete spacetime structure is obtained. With the discrete spacetime, we can explain the uncertainty principle. Based on the hypothesis of information theory and the entropy of black holes, we get the precise value of the parameter χ and demonstrate the reason why the entropy bounds hold.
ON DESIGN OF A COUPLING COMPONENT FOR PARALLEL MULTIMODELING
Authors: WANG DALI , HARMON MICHAEL , BERRY MICHAEL , GROSS LOUIS
Published: August 2011

A component-based simulation framework is a favorable choice for parallel multiscale simulations, which require a dedicated coupling component to support flexible data communication/exchange, computational parallelism, and on-demand dynamic load balancing. In this paper, a coupling component (the Coupler) was designed to support integrated parallel multimodeling. An integrated ecological multimodeling, part of the across trophic level system simulation (ATLSS) for Everglades ecosystem restoration, has been used to demonstrate the advantage of the Coupler for natural resource management applications.
Cutting-Edge Technology of Bismuth-Based High-Temperature Superconducting Wires for Application in Energy- and Environment-Related Fields
Authors: Hayashi Kazuhiko
Published: August 2011

The first bismuth-based superconductor was discovered by Dr. Maeda of National Research Institute for Metals (currently, National Institute for Materials Science) in 1988. Since then, Sumitomo Electric Industries, Ltd., has been attempting to improve the fabrication method of superconducting wires and to develop products applying bismuth-based superconductors. As a result, the length of wires that can be fabricated has steadily increased as well as the wire performance, and these achievements have led to the practical use of prototype products and demonstration projects worldwide. Bismuth-based superconducting wires were established as an industrial material along with the development of an over pressure sintering method. In addition to this industrial accomplishment, these wires are now ready for practical use in application fields such as power cables and large-scale motors for ships. Superconductivity is an ultimate energy-saving technology, and its practical utilization is expected to contribute to the reduction of CO2 emission and the prevention of global warming.
Determination of Polar Anchoring Strength for Polymer-Stabilized Blue Phase Liquid Crystal Device
Authors: Lias Jais Bin , Kikuchi Hirotsugu , Kimura Munehiro , Akahane Tadashi
Published: August 2011

Quantitative evaluation of a coupling coefficient between the blue phase (BP) liquid crystal (LC) and the diacrylate-type polymer, which is to be either the framework or the defect line of the polymer-stabilized (PS) BPLC, is an important subject. As a coupling coefficient, the polar anchoring strength W

d
between the BPLC and the diacrylate-type polymer prepared inside a thin hybrid alignment nematic (HAN) cell was evaluated by means of oblique incidence transmission spectroscopic ellipsometry. As an example, the polar anchoring strength W

d
= 1.87 ×10-4 J/m2 is measured at the interface between host BPLC material with the diacrylate-type polymer performing vertical alignment (VA).
Dual Metal/High-k Gate-Last Complementary Metal–Oxide–Semiconductor Field-Effect Transistor with SiBN Film and Characteristic Behavior In Sub-1-nm Equivalent Oxide Thickness
Authors: Kikuchi Yoshiaki , Wakabayashi Hitoshi , Tsukamoto Masanori , Nagashima Naoki
Published: August 2011

For the first time, dual metal/high-k gate-last complementary metal–oxide–semiconductor field-effect transistors (CMOSFETs) with low-dielectric-constant-material offset spacers and several gate oxide thicknesses were fabricated to improve CMOSFETs characteristics. Improvements of 23 aF/µm in parasitic capacitances were confirmed with a low-dielectric-constant material, and drive current improvements were also achieved with a thin gate oxide. The drive currents at 100 nA/µm off leakages in n-type metal–oxide–semiconductor (NMOS) were improved from 830 to 950 µA/µm and that in p-type metal–oxide–semiconductor (PMOS) were from 405 to 450 µA/µm with a reduction in gate oxide thickness. The thin gate oxide in PMOS was thinner than that in NMOS and the gate leakage was increased. However the gate leakage did not affect the off leakage below a gate length of about 44 nm. On the basis of this result, in these gate-last CMOSFETs, it is concluded that the transistors have potential for further reduction of the equivalent oxide thickness without an increase in off leakages at short gate lengths for high off leakage CMOSFETs. For low off leakage CMOSFETs, the optimization of wet process condition is needed to prevent the reduction of the 2 nm HfO2 thickness in PMOS during a wet process.
Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure
Authors: Kwon Jung-Dae , Rha Jong-Joo , Nam Kee-Seok , Park Jin-Seong
Published: August 2011

Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.
Power Spectrum of Smoothed Line-Edge and Line-Width Roughness
Authors: Hiraiwa Atsushi , Nishida Akio
Published: August 2011

Line-edge and line-width roughness (LER and LWR) is a challenge for device variability control, especially in future devices. Actual device patterns have LER/LWR that is smoothed from the original photoresist patterns used as etching masks. In this study, the LER/LWR of these actual patterns was assumed to have a modified exponential autocorrelation function, which was smoothed by another exponential function. An analytical formula of the discrete power spectral density (PSD) of this LER/LWR was derived on the basis of the previous formula for non-smoothed LER/LWR, for use in a PSD fitting method. The PSDs calculated using this formula excellently fit the experimental PSDs of both types of polycrystalline-silicon lines without and with sidewall spacers. Through these fittings, it was found that the actual LER/LWR is accurately characterized using the variance and correlation length of the original non-smoothed LER/LWR simply by introducing a third parameter that characterizes the smoothing effect.
Combinatorial Search for Ni–Nb–Ti Thin Film Amorphous Alloys with High Corrosion Resistances
Authors: Sakurai Junpei , Kozako Hiroshi , Mukai Nobuyuki , Ohnuma Yoshinori , Takahashi Tsutomu , Hata Seiichi
Published: August 2011

In this paper, we present a combinatorial search for novel Ni–Nb–Ti thin film amorphous alloys suitable for use in diaphragm-type microelectromechanical systems (MEMS) vacuum sensors. The corrosion resistances to ClF3 gas and heat resistances of the thin films were evaluated by a combinatorial method that enables efficient searching for candidate materials. The combinatorial evaluation revealed that Ni56Nb33Ti11 and Ni49Nb35Ti16 thin film amorphous alloys exhibit a high heat resistance and a high corrosion resistance to ClF3 gas. Moreover, both samples exhibited high fracture stresses of over 1.0 GPa. Both samples were assessed to be suitable diaphragm materials for diaphragm-type MEMS vacuum sensors. We also fabricated and evaluated a simple diaphragm-type MEMS vacuum sensor using a Ni49Nb35Ti16 thin film amorphous alloy; the results confirmed the suitability of this amorphous alloy as a diaphragm material.
Development of the Large Scanning Mirror Using Fe-Based Metallic Glass Ribbon
Authors: Lee Jae-Wung , Lin Yu-Ching , Chen Na , Louzguine D. V. , Esashi Masayoshi , Gessner Thomas
Published: August 2011

In order to achieve the large scanning angle without mechanical failure during actuation, the micro-mirror structure was fabricated using Fe-based metallic glass (MG) ribbon. High values of mechanical strength and elastic strain limit are desired for the torsion bar for providing high performance of the mirror, including large tilting angle and good stability. MG materials guarantee superior value of elastic strain limit and fracture toughness resulting from its amorphous structure without line defects like dislocations and grain boundaries. We chose Fe-base MG material for mirror actuation according to its good soft magnetic properties and simple structure without any further step of integration of magnetic material. Millimeter-size mirror device was successfully fabricated by laser machining techniques from Fe-based MG ribbon. Extremely large optical tilting angle of exceeding 100° was obtained on activation of the mirror by magnetic force when electrical current of 100 mA was applied. Large tilting angle of the mirror is due to the torsion bar which was fabricated with Fe-based MG material that has large elastic strain limit and high fracture toughness.
Low Sheet Resistivity of Transparent Ga-Doped ZnO Film Grown by Atmospheric Spray Pyrolysis
Authors: Takemoto Yujin , Oshima Minoru , Yoshino Kenji , Toyota Kouji , Inaba Koichiro , Haga Ken-ichi , Tokudome Koichi
Published: August 2011

Ga-doped ZnO film on polyethylene terephthalate film was successfully grown at 150 °C by conventional atmospheric spray pyrolysis using diethylzinc-based solution. The samples had an average optical transmittance of more than 80% and were strongly a-axis orientated according to the result of optical transmittance and X-ray diffraction analyses, respectively. The n-type Ga-doped ZnO films had a low sheet resistivity of 250 Ω/□ at an optimal Ga content of 1 at. % upon UV irradiation.
Bonding and Photoluminescence Characteristics of GaInAsP/InP Membrane Structure on Silicon-on-Insulator Waveguides by Surface Activated Bonding
Authors: Osabe Ryo , Okumura Tadashi , Kondo Simon , Nishiyama Nobuhiko , Arai Shigehisa
Published: August 2011

Surface activated bonding (SAB) technology was investigated to realize InP-based active photonic devices on a silicon-on-insulator (SOI) substrate for highly compact photonic integrated circuits (PICs). A wide area five-quantum-wells (5QWs) GaInAsP/InP membrane structure was successfully bonded onto an SOI waveguide using a low-temperature (150 °C) N2 plasma SAB method. The full width at half maximum (FWHM) of the photoluminescence (PL) of the 5QWs membrane structure on SOI was comparable to that of conventional QWs. It was revealed that the PL intensity distribution and peak wavelength shift of the GaInAsP 5QWs structure around the Si waveguides were small.
Novel Atmospheric Pressure Inductively Coupled Micro Plasma Source Using Floating Wire Electrode
Authors: Kumagai Shinya , Matsuyama Hiroki , Yokoyama Yoshihiro , Hori Masaru , Sasaki Minoru
Published: August 2011

A novel atmospheric pressure inductively coupled micro-plasma (ICMP) source is proposed. The gas flow channel is prepared inside the center of the U-shaped Cu electrode of a one-turn antenna coil. The plasma region is the center linear trench designed for the optical coupling with the slit aperture of the spectrometer. A floating wire electrode is first placed inside the trench of the gas channel without the wired connection to the power source. A glass window plate covers the gas channel allowing the optical emission from the linear trench. Under He gas flow, the plasma ignites at ∼18 W of 100 MHz very high frequency (VHF) power, and the optical emission increases with the power. Without the floating wire electrode, the plasma does not ignite even at 200 W. The floating wire electrode enhances the ignition. The characteristics of the floating wire electrode and the ICMP source are described.
Spatiotemporal Distribution of Nitrogen Rotational Temperature during Pulsed Discharge in Air
Authors: Okada Sho , Wang Douyan , Namihira Takao , Katsuki Sunao , Akiyama Hidenori
Published: August 2011

We have investigated the gas temperature during pulsed discharge. The gas temperature is one of the most important parameters for application of pulsed discharge in atmospheric gases. At atmospheric pressure gases, the gas temperature can be assumed equal to its rotational temperature. In the present work, the rotational temperature of the nitrogen molecules in a coaxial discharge reactor was obtained by synthesizing measured and calculated spectra. The emission spectrum was obtained from the second positive system of the nitrogen molecule due to the transition from the C3Πu state to the B3Πg state. As the result, rapidly increasing of the temperature (approximately 60 K) was observed at the boundary between the streamer and the glow-like discharge phases. In this paper, the spatial and the temporal dependences of the rotational temperature during pulsed discharge are reported.
Boltzmann Equation Analysis of Electron Transport in a N2–O2Streamer Discharge
Authors: Dujko Saša , Ebert Ute , White Ronald D. , Petrović Zoran Lj.
Published: August 2011

A comprehensive investigation of electron transport in N2–O2mixtures has been carried out using a multi term theory for solving the Boltzmann equation instead of conventional two term theory often employed in plasma modeling community. We focus on the way in which the transport coefficients and spatially resolved transport data are influenced by the amount of O2in the mixture. Emphasis is placed upon the explicit and implicit effects of non-conservative collisions, ionization and attachment on various transport coefficients. In particular, the effects of three-body attachment for electrons on various transport data are considered. It is found that the differences between two sets of transport coefficients, bulk and flux, resulting from the explicit influence of non-conservative collisions is sensitive to the quantity of O2in the mixture.
Purified Silicon Film Formation from Metallurgical-Grade Silicon by Hydrogen-Plasma-Induced Chemical Transport
Authors: Ohmi Hiromasa , Yamada Takahiro , Kakiuchi Hiroaki , Yasutake Kiyoshi
Published: August 2011

A purified Si film is prepared directly from metallurgical-grade (MG) Si by chemical transport using sub-atmospheric pressure H2 plasma. The purification mechanism is based on the selective etching of Si using atomic H. It is demonstrated that the concentrations of most metal impurities (e.g., Fe, Cr, Ni, Ti, and Mn) in the prepared Si film are in the acceptable range for solar-grade Si material, or below the determination limit of the several impurity measuring methods employed in this study. From the infrared absorption measurements of the etching product produced by the reaction between H2 plasma and MG-Si, it is found that the main etching product is SiH4. Therefore, a remote-type chemical transport process is developed to produce SiH4 gas directly from MG-Si. Using other purifying principles (such as a pyrolysis filter in combination with this process), it is demonstrated that purified Si films about B, P and metal atoms can be produced from metallurgical-grade Si (<98% purity).
Deposition of Fluorinated Diamond-Like-Carbon Films by Exposure of Electrothermal Pulsed Plasmas
Authors: Kimura Takashi , Iida Masayasu
Published: August 2011

Thin amorphous carbon films are deposited on silicon substrates by exposure to pulsed plasmas where the feed gas is mainly generated from the ablation of an insulator. An electrothermal pulsed plasma thruster with a discharge room in an insulator rod is used as the pulsed plasma for the ablation of the insulator, and the material of the insulator rod is poly(tetrafluoroethylene) (PTFE). The pulsed plasma, in which the estimated electron density is on the order of 1022–1023 m-3, is generated by the stored energy in the capacitor. The deposition rate, which depends on the stored energy, is lower than 1 nm per pulse in our experiment. The maximum hardness measured using a nanoindenter is about 7 GPa at a stored energy of about 2.7 J, beyond which the hardness of the films decreases with the increase in stored energy. Raman spectroscopy is also carried out to examine the formation of fluorinated diamond-like carbon films. In addition, the influence of dilution gas on the properties of the deposited films is also investigated.
Analysis of GaN Damage Induced by Cl2/SiCl4/Ar Plasma
Authors: Minami Masaki , Tomiya Shigetaka , Ishikawa Kenji , Matsumoto Ryosuke , Chen Shang , Fukasawa Masanaga , Uesawa Fumikatsu , Sekine Makoto , Hori Masaru , Tatsumi Tetsuya
Published: August 2011

GaN-based optical devices are fabricated using a GaN/InGaN/GaN sandwiched structure. The effect of radicals, ions, and UV light on the GaN optical properties during Cl2/SiCl4/Ar plasma etching was evaluated using photoluminescence (PL) analysis. The samples were exposed to plasma (radicals, ions, and UV light) using an inductively coupled plasma (ICP) etching system and a plasma ion beam apparatus that can separate the effects of UV and ions both with and without covering the SiO2 window on the surface. Etching damage in an InGaN single quantum well (SQW) was formed by exposing the sample to plasma. The damage, which decreases PL emission intensity, was generated not only by ion beam irradiation but also by UV light irradiation. PL intensity decreased when the thickness of the upper GaN layer was etched to less than 60 nm. In addition, simultaneous irradiation of UV light and ions slightly increased the degree of damage. There seems to be a synergistic effect between the UV light and the ions. For high-quality GaN-based optoelectronics and power devices, UV light must be controlled during etching processes in addition to the etching profile, selectivity, and ion bombardment damage.
Redox Characteristics of Thiol Compounds Using Radicals Produced by Water Vapor Radio Frequency Discharge
Authors: Hayashi Nobuya , Nakahigashi Akari , Goto Masaaki , Kitazaki Satoshi , Koga Kazunori , Shiratani Masaharu
Published: August 2011

The redox reaction between cystein and cystine is observed using radicals produced in water vapor plasma for the control of plant growth. Cystein is oxidized to cystine using the OH radical in the higher-pressure regime and cystine is reduced to cystein by the H radical generated in the lower-pressure regime. Also, the oxidative stress reaction of plants is observed when water vapor plasma is irradiated onto seeds of plants such as radish sprouts. The mechanism of the control of plant growth is explained by the change in thiol compound quantity of the plant cells induced by the radical reaction.
Pulsed Neodymium-Doped Yttrium Aluminum Garnet Laser Heating of Multiwalled Carbon Nanotube Film
Authors: Nakamiya Toshiyuki , Iwasaki Yoichiro , Kozai Ryosuke , Sonoda Yoshito , Mitsugi Fumiaki , Semba Keisuke , Ikegami Tomoaki , Aoqui Shinichi , Muramoto Ikuya
Published: August 2011

A multiwalled carbon nanotube (MWCNT) film surface was irradiated with a single pulse from a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. When an MWCNT film is irradiated with a pulsed Nd:YAG laser of 23.7 mJ/cm2, the calculated maximum surface temperature becomes 304 °C. The surface temperature increases from 595 to 2968 °C with an increase in laser power from 59.4 to 469 mJ/cm2. The MWCNT film is examined by increasing the intensity of the two characteristic Raman shifts I
D (defect-induced mode: D-band) and I
G (graphite-induced mode: G-band) to clarify the effect of pulsed Nd:YAG laser heating. Moreover, a new original image analytical method is developed to characterize CNTs from scanning electron microscopy (SEM) images. This method is useful for measuring the diameter of as-grown CNTs and those after annealing with a pulsed Nd:YAG laser. The number of detected diameters between 40 and 60 nm increases with an increase in laser energy density from 181 to 268 mJ/cm2.
Formation of Nanofibers on the Surface of Diamond-Like Carbon Films by RF Oxygen Plasma Etching
Authors: Harigai Tooru , Koji Hirofumi , Furuta Hiroshi , Hatta Akimitsu
Published: August 2011

Diamond-like carbon (DLC) nanosize fibers were formed by etching DLC films using RF O2 plasma. The DLC films were grown on silicon substrates by an RF plasma chemical vapor deposition (CVD) method, and a small amount of Ni was deposited on the DLC films using a DC magnetron sputtering method before the etching. DLC fibers of 20 nm diameter and 600 nm height were found on the etched surfaces of the DLC films. DLC fibers of similar size that were highly insulating were also obtained by O2 etching without the deposition of Ni. It was found that Al from the RF electrode was sputtered and contaminated the DLC surface during etching, which would have affected the formation of fibers. The anisotropic etching of DLC and the ion-induced growth of carbon fibers are discussed as the formation mechanisms of the DLC fibers. The DLC fibers bent and stuck together during a field-emission scanning electron microscope observation, especially in the slow scanning mode. Such soft fibers can exist vertically and straightly throughout the etching in RF plasma.
Estimation of Ion/Radical Flux from Mask Selectivity and Etching Rate Calibrated by Topography Simulation
Authors: Ohmine Toshimitsu , Deshpande Vaibhav , Takada Hideki , Ikeda Tomoharu , Saito Hirokazu , Kawai Fumiaki , Hamada Kimimori
Published: August 2011

A simple method for the estimation of ion/radical fluxes in an ion-assisted etching process was developed for SF6/O2/Si etching utilizing the difference in etching mechanism between SiO2mask and the silicon substrate. It was derived that F coverage of a silicon surface is approximately a linear function of the selectivity of the two materials, from which the incident ion flux and F flux are calculated. The selectivity-to-coverage proportional constant was determined using a topography simulator so that the general trend of etching profiles matched those of the experiment. The obtained fluxes showed reasonable qualitative trends in terms of reactor operational conditions and reactor parameters. The feature profiles simulated by the topography simulator using these flux values were in good agreement with those of scanning electron microscopy (SEM) experimental data over a wide range of operating conditions and machine configurations.
Disappearance of Lowest-Order Transmission Resonance in Ag Film of Critical Thickness
Authors: Lu Shin-Ming , Huang Hsu-Sheng , Su Wei-Bin , Chu Pei-Hong , Chang Chia-Seng , Hsiao Hsi-Lien , Tsong Tien Tzou
Published: August 2011

The quantum phenomenon of the transmission resonance can be observed in Ag films grown on a Si(111)7×7 surface using scanning tunneling spectroscopy. It is found that the energy of the transmission resonance moves toward lower energy with increasing film thickness. The formula used is derived from quantum mechanics to demonstrate that this lowering in the transmission resonance energy is proportional to (w+1)2/w2, wherewis the number of atomic layers of film thickness. This relation is justified by experimental results, but only holds for thinner films. The formula also predicts that the lowest-order transmission resonance should disappear when the Ag film reaches its critical thickness. This disappearance of the transmission resonance has also been experimentally confirmed in thedI/dVspectrum.
In situ Observation of Surface Reconstruction of Si(001) with Stress/Strain Field Scanning Probe Microscopy
Authors: Fujita Guo
Published: August 2011

In this study, the surface reconstruction of Si(001) was observedin situby stress/strain field scanning probe microscopy (SF-SPM). This SF-SPM system includes two independent probes that can be operated as scanning tunneling microscope (STM) or atomic force microscope (AFM) freely. A special structure of the AFM probe is designed with a piezo-resistive cantilever sensor to make the probe head compact to be set in a limited space of ultrahigh-vacuum (UHV) chambers. With a low-noise direct current power source, the atomic-resolution STM and AFM images of the Si(111) and Si(001) surfaces at room temperature and high temperature were obtained. Using this system, the relationship between the reconstruction of the Si(001) surface with stress and time was investigated.
Electronic Modification of C60 Monolayers via Metal Substrates
Authors: Yamada Yoichi , Yamada Shuntaro , Nakayama Takuto , Sasaki Masahiro , Tsuru Tomohito
Published: August 2011

The structural and electronic modifications of C60 monolayer on Cu(111) and Pt(111) have been studied by scanning tunneling microscopy. On Cu(111), controlled experiments demonstrated that the electronic structure of the C60 layer changes markedly with increasing extent of interaction between the C60 layer and the substrate. The most strongly interacting monolayer exhibited a metallic density of states at the Fermi energy. On Pt(111), where the interaction between the C60 layer and the substrate is stronger, the annealing of the monolayer caused the decomposition of the C60 layer, resulting in graphene formation instead of polymerization.
Deposition Sequence Determines Morphology of C60 and 3,4,9,10-Perylenetetracarboxylic Diimide Islands on CaF2(111)
Authors: Loske Felix , Reichling Michael , Kühnle Angelika
Published: August 2011

The coadsorption of C60 and 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) molecules on atomically flat terraces of the CaF2(111) surface is studied under ultra-high vacuum conditions using non-contact atomic force microscopy (NC-AFM). Deposition of PTCDI molecules on CaF2(111) yields needle-shaped, molecularly well-ordered crystals. Upon following deposition of C60 molecules, the PTCDI islands are completely covered by C60. For the opposite deposition order, the initially grown C60 islands are not covered by PTCDI molecules, instead, most of the PTCDI molecules condense in pure islands, while only few PTCDI molecules nucleate at the edges of previously grown C60 islands. Simultaneous deposition of both molecules results in an intermixed phase with yet another island morphology. The observed fundamental differences in island morphology suggest that different dewetting barriers are involved in the formation process.
High-Resolution Imaging of Plasmid DNA in Liquids in Dynamic Mode Atomic Force Microscopy Using a Carbon Nanofiber Tip
Authors: Kitazawa Masashi , Ito Shuichi , Yagi Akira , Sakai Nobuaki , Uekusa Yoshitugu , Ohta Ryo , Inaba Kazuhisa , Hayashi Akari , Hayashi Yasuhiko , Tanemura Masaki
Published: August 2011

To understand the motion of DNA and DNA complexes, the real-time visualization of living DNA in liquids is quite important. Here, we report the high-resolution imaging of plasmid DNA in water using a rapid-scan atomic force microscopy (AFM) system equipped with a carbon nanofiber (CNF) probe. To achieve a rapid high-resolution scan, small SiN cantilevers with dimensions of 2 (width) × 0.1 (thickness) × 9 µm (length) and a bent end (tip view structure) were employed as base cantilevers onto which single CNFs were grown. The resonant frequencies of the cantilever were 1.5 MHz in air and 500 kHz in water, and the spring constant was calculated to be 0.1 N/m. Single CNFs, typically 88 nm in length, were formed on an array of the cantilevers in a batch process by the ion-irradiation method. An AFM image of a plasmid DNA taken in water at 0.2 fps (5 s/image) using a batch-fabricated CNF-tipped cantilever clearly showed the helix turns of the double strand DNA. The average helical pitch measured 3.4 nm (σ: 0.5 nm), which was in good agreement with that determined by the X-ray diffraction method, 3.4 nm. Thus, it is presumed that the combined use of the rapid-scan AFM system with the ion-induced CNF probe is promising for the dynamic analysis of biomolecules.
The indication of Martian gully formation processes by slope–area analysis
Authors: Conway Susan J. , Balme Matthew R. , Murray John B. , Towner Martin C. , Okubo Chris H. , Grindrod Peter M.
Published: August 2011

The formation process of recent gullies on Mars is currently under debate. This study aims to discriminate between the proposed formation processes – pure water flow, debris flow and dry mass wasting – through the application of geomorphological indices commonly used in terrestrial geomorphology. High-resolution digital elevation models (DEMs) of Earth and Mars were used to evaluate the drainage characteristics of small slope sections. Data from Earth were used to validate the hillslope, debris-flow and alluvial process domains previously found for large fluvial catchments on Earth, and these domains were applied to gullied and ungullied slopes on Mars. In accordance with other studies, our results indicate that debris flow is one of the main processes forming the Martian gullies that were being examined. The source of the water is predominantly distributed surface melting, not an underground aquifer. Evidence is also presented indicating that other processes may have shaped Martian crater slopes, such as ice-assisted creep and solifluction, in agreement with the proposed recent Martian glacial and periglacial climate. Our results suggest that, within impact craters, different processes are acting on differently oriented slopes, but further work is needed to investigate the potential link between these observations and changes in Martian climate.
Landscape evolution in Martian mid-latitude regions: insights from analogous periglacial landforms in Svalbard
Authors: Hauber E. , Reiss D. , Ulrich M. , Preusker F. , Trauthan F. , Zanetti M. , Hiesinger H. , Jaumann R. , Johansson L. , Johnsson A. , Van Gasselt S. , Olvmo M.
Published: August 2011

Periglacial landforms on Spitsbergen (Svalbard, Norway) are morphologically similar to landforms on Mars that are probably related to the past and/or present existence of ice at or near the surface. Many of these landforms, such as gullies, debris-flow fans, polygonal terrain, fractured mounds and rock-glacier-like features, are observed in close spatial proximity in mid-latitude craters on Mars. On Svalbard, analogous landforms occur in strikingly similar proximity, which makes them useful study cases to infer the spatial and chronological evolution of Martian cold-climate surface processes. The analysis of the morphological inventory of analogous landforms on Svalbard and Mars allows the processes operating on Mars to be constrained. Different qualitative scenarios of landscape evolution on Mars help to better understand the action of periglacial processes on Mars in the recent past.
Knockout of the Na,K-ATPase α2-isoform in the cardiovascular system does not alter basal blood pressure but prevents ACTH-induced hypertension
Authors: Rindler Tara N. , Dostanic Iva , Lasko Valerie M. , Nieman Michelle L. , Neumann Jonathan C. , Lorenz John N. , Lingrel Jerry B.
Published: August 2011

The α2-isoform of Na,K-ATPase (α2) is thought to play a role in blood pressure regulation, but the specific cell type(s) involved have not been identified. Therefore, it is important to study the role of the α2in individual cell types in the cardiovascular system. The present study demonstrates the role of vascular smooth muscle α2in the regulation of cardiovascular hemodynamics. To accomplish this, we developed a mouse model utilizing the Cre/LoxP system to generate a cell type-specific knockout of the α2in vascular smooth muscle cells using the SM22α Cre. We achieved a 90% reduction in the α2-expression in heart and vascular smooth muscle in the knockout mice. Interestingly, tail-cuff blood pressure analysis reveals that basal systolic blood pressure is unaffected by the knockout of α2in the knockout mice. However, knockout mice do fail to develop ACTH-induced hypertension, as seen in wild-type mice, following 5 days of treatment with ACTH (Cortrosyn; wild type = 119.0 ± 6.8 mmHg; knockout = 103.0 ± 2.0 mmHg). These results demonstrate that α2-expression in heart and vascular smooth muscle is not essential for regulation of basal systolic blood pressure, but α2is critical for blood pressure regulation under chronic stress such as ACTH-induced hypertension.
Blockade of the TP receptor attenuates the exercise pressor reflex in decerebrated rats with chronic femoral artery occlusion
Authors: Leal Anna K. , McCord Jennifer L. , Tsuchimochi Hirotsugu , Kaufman Marc P.
Published: August 2011

Cyclooxygenase metabolites stimulate or sensitize group III and IV muscle afferents, which comprise the sensory arm of the exercise pressor reflex. The thromboxane (TP) receptor binds several of these metabolites, whose concentrations in the muscle interstitium are increased by exercise under freely perfused conditions and even more so under ischemic conditions, which occur in peripheral artery disease. We showed that the exercise pressor reflex is greater in rats with simulated peripheral artery disease than in rats with freely perfused limbs. These findings prompted us to test the hypothesis that the TP receptor contributes to the exaggerated exercise pressor reflex occurring in a rat model of peripheral artery disease. We compared the cardiovascular responses to static contraction and stretch before and after femoral arterial injections of daltroban (80 μg), a TP receptor antagonist. We performed these experiments in decerebrate rats whose femoral arteries were ligated 72 h before the experiment (a model of simulated peripheral artery disease) and in control rats whose hindlimbs were freely perfused. Daltroban reduced the pressor response to static contraction in both freely perfused ( n = 6; before: Δ12 ± 2 mmHg, after: Δ6 ± 2 mmHg, P = 0.024) and 72-h-ligated rats ( n = 10; before: Δ25 ± 3 mmHg, after: Δ7 ± 4 mmHg, P = 0.001). Likewise, daltroban reduced the pressor response to stretch in the freely perfused group ( n = 9; before: Δ30 ± 3 mmHg, after: Δ17 ± 3 mmHg, P < 0.0001) and in the ligated group ( n = 11; before: Δ37 ± 5 mmHg, after: Δ23 ± 3 mmHg, P = 0.016). Intravenous injections of daltroban had no effect on the pressor response to contraction. We conclude that the TP receptor contributes to the pressor responses evoked by contraction and stretch in both freely perfused rats and rats with simulated peripheral artery disease.
TMEM16A channels generate Ca2+-activated Cl− currents in cerebral artery smooth muscle cells
Authors: Thomas-Gatewood Candice , Neeb Zachary P. , Bulley Simon , Adebiyi Adebowale , Bannister John P. , Leo M. Dennis , Jaggar Jonathan H.
Published: August 2011

Transmembrane protein (TMEM)16A channels are recently discovered membrane proteins that display electrophysiological properties similar to classic Ca2+-activated Cl− (ClCa) channels in native cells. The molecular identity of proteins that generate ClCa currents in smooth muscle cells (SMCs) of resistance-size arteries is unclear. Similarly, whether cerebral artery SMCs generate ClCa currents is controversial. Here, using molecular biology and patch-clamp electrophysiology, we examined TMEM16A channel expression and characterized Cl− currents in arterial SMCs of resistance-size rat cerebral arteries. RT-PCR amplified transcripts for TMEM16A but not TMEM16B–TMEM16H, TMEM16J, or TMEM16K family members in isolated pure cerebral artery SMCs. Western blot analysis using an antibody that recognized recombinant (r)TMEM16A channels detected TMEM16A protein in cerebral artery lysates. Arterial surface biotinylation and immunofluorescence indicated that TMEM16A channels are located primarily within the arterial SMC plasma membrane. Whole cell ClCa currents in arterial SMCs displayed properties similar to those generated by rTMEM16A channels, including Ca2+ dependence, current-voltage relationship linearization by an elevation in intracellular Ca2+ concentration, a Nerstian shift in reversal potential induced by reducing the extracellular Cl− concentration, and a negative reversal potential shift when substituting extracellular I− for Cl−. A pore-targeting TMEM16A antibody similarly inhibited both arterial SMC ClCa and rTMEM16A currents. TMEM16A knockdown using small interfering RNA also inhibited arterial SMC ClCa currents. In summary, these data indicate that TMEM16A channels are expressed, insert into the plasma membrane, and generate ClCa currents in cerebral artery SMCs.
Short-term oral progesterone administration antagonizes the effect of transdermal estradiol on endothelium-dependent vasodilation in young healthy women
Authors: Miner Jennifer A. , Martini Emily R. , Smith Michael M. , Brunt Vienna E. , Kaplan Paul F. , Halliwill John R. , Minson Christopher T.
Published: August 2011

Very few studies have explored the cardiovascular effects of progesterone in premenopausal women. This study aimed to examine the short-term effects of oral progesterone alone, transdermal estrogen alone, and progesterone and estrogen combined on flow-mediated dilation (FMD) in healthy reproductive-aged women. We suppressed endogenous estrogens and progesterone in 17 premenopausal women for 10–12 days using a gonadotropin-releasing hormone antagonist. On day 4 (hormone suppression condition), subjects were tested ( n = 17) and were then supplemented with either 200 mg micronized progesterone ( n = 8) orally or 0.1 mg estradiol ( n = 9) transdermally per day. On day 7 (progesterone-first or estradiol-first condition), subjects were tested and began supplementation with both hormones ( n = 17) and were tested again on day 10 (combined hormone condition). FMD of the brachial artery was assessed using B-mode arterial ultrasound, combined with synchronized Doppler analysis. As a result, significant differences in FMD were observed between hormone suppression (7.85 ± 1.06%) and estrogen-first conditions (10.14 ± 1.40%; P < 0.05). The estradiol-induced increase was abolished when oral progesterone was also supplemented (6.27 ± 0.96%). In contrast, we observed a trend toward a decrease in FMD with unopposed progesterone administration, but no statistically significant differences were found between the progesterone-first (6.66 ± 1.23%), hormone suppression (7.80 ± 1.23%), and combined hormone conditions (7.40 ± 1.29%). In conclusion, these data suggest that short-term oral micronized progesterone administration antagonizes the beneficial effect of transdermal estradiol on FMD.
Mechanisms underlying altered extracellular nucleotide-induced contractions in mesenteric arteries from rats in later-stage type 2 diabetes: effect of ANG II type 1 receptor antagonism
Authors: Ishida Keiko , Matsumoto Takayuki , Taguchi Kumiko , Kamata Katsuo , Kobayashi Tsuneo
Published: August 2011

Little is known about the vascular contractile responsiveness to, and signaling pathways for, extracellular nucleotides in the chronic stage of type 2 diabetes or whether the ANG II type 1 receptor blocker losartan might alter such responses. We hypothesized that nucleotide-induced arterial contractions are augmented in diabetic Goto-Kakizaki (GK) rats and that treatment with losartan would normalize the contractions. Here, we investigated the vasoconstrictor effects of ATP/UTP in superior mesenteric arteries isolated from GK rats (37–42 wk old) that had or had not received 2 wk of losartan (25 mg·kg−1·day−1). In arteries from GK rats (vs. those from Wistar rats), 1) ATP- and UTP-induced contractions, which were blocked by the nonselective P2 antagonist suramin, were enhanced, and these enhancements were suppressed by endothelial denudation, by cyclooxygenase (COX) inhibitors, or by a cytosolic phospholipase A2 (cPLA2) inhibitor; 2) both nucleotides induced increased release of PGE2 and PGF2α; 3) nucleotide-stimulated cPLA2 phosphorylations were increased; 4) COX-1 and COX-2 expressions were increased; and 5) neither P2Y2 nor P2Y6 receptor expression differed, but P2Y4 receptor expression was decreased. Mesenteric arteries from GK rats treated with losartan exhibited (vs. untreated GK) 1) reduced nucleotide-induced contractions, 2) suppressed UTP-induced release of PGE2 and PGF2α, 3) suppressed UTP-stimulated cPLA2 phosphorylation, 4) normalized expressions of COX-2 and P2Y4 receptors, and 5) reduced superoxide generation. Our data suggest that the diabetes-related enhancement of ATP-mediated vasoconstriction was due to P2Y receptor-mediated activation of the cPLA2/COX pathway and, moreover, that losartan normalizes such contractions by a suppressing action within this pathway.