bluuebunny/crossref_metadata_2025_split huggingface dataset:
FRANK STARLING MECHANISM ON ALTERNATING PUMP VENTRICULAR MODELS
Authors: ZANNOLI ROMANO , SORBELLO S. , CORAZZA I. , PEPE G. , LEPERA G. , BRANZI A. 
Published: October 2002

An alternating pump system simulating the left ventricle in a mechanical cardio-vascular model, has been modified to show Frank Starling regulating mechanism. An inextensible thin plastic wall chamber has been put around the syringe's core and connected to the internal syringe's chamber by two lateral holes. During the filling and the expulsion phases the external chamber changes his volume and the net output depends on the filling pressure. The regulating mechanism shows a beat to beat response and the dependence of systolic aortic pressure, systolic ventricular work, stroke output with respect ventricular filling pressure show a "physiological" behavior. This solution will be introduced in the mechanical whole model to study the changes of aorto-ventricular interaction by changing aortic compliance.
Growth of ZnSxSe1-x Crystals from ZnSe–Sb2S3–Sb2Se3 Solutions
Authors: Hiroyuki Araki Hiroyuki Araki , Hisashi Kanie Hisashi Kanie , Masatoshi Sano Masatoshi Sano 
Published: October 2002

ZnS

x

Se1-
x

crystals were grown in ampoules from ZnSe–Sb2S3–Sb2Se3 solutions, cooling from 1000°C to 700°C at a rate of 9°C/h. All grown crystals had zincblende structure. The sulfur composition x was varied from 0 to 0.99 by changing the sulfur fraction [S]/([S]+[Se]) in the starting material. The value of x was larger than the sulfur fraction in the starting material. The amount of Sb in all the grown crystals was undetectable ( <0.01 at.%). The sulfur composition dependence of the lowest gap determined from a photoluminescence excitation spectrum was represented as E
0(x)=2.82+0.35x+0.63x
2 (eV) at 4.2 K. The energy of the peak position in a cathodoluminescence spectrum at room temperature was close to the energy of the lowest gap throughout the entire composition range.
Photoreflectance Study of Interface Roughness in Ge/SiGe Strained-Layer Heterostructures
Authors: Hiroyuki Yaguchi Hiroyuki Yaguchi , Kaori Tai Kaori Tai , Keizo Takemasa Keizo Takemasa , Kentaro Onabe Kentaro Onabe , Yasuhiro Shiraki Yasuhiro Shiraki , Ryoichi Ito Ryoichi Ito 
Published: October 2002

Ge/SiGe strained-layer heterostructures have been investigated using photoreflectance (PR) spectroscopy. On the basis of the comparison between the experimental and calculated quantum well-related transition energies formed at the Γ point, band discontinuities at the Ge/SiGe heterojunction are determined and found to vary linearly with Ge content in the SiGe layer. Conduction band offset ratioQc(= ΔEc/(ΔEc+ΔEvHH)) at the Γ point is evaluated to be 0.68 ±0.08 . From the intrinsic linewidth of the quantum well-related transitions, roughness at the Ge/SiGe heterointerface has been characterized for the first time and is estimated to be ±1 monolayer (ML). In addition, the splittings in the PR spectra are observed in some samples at low temperatures. These splittings are due to the difference in the well width and correspond to the height (or depth) of about 10 ML.
Room-Temperature Photoreflectance Characterization of InAlAs/InGaAs Heterojunction Bipolar Transistor Structure Including Two-Dimensional Electron Gas
Authors: Yau-Huei Chen Yau-Huei Chen , Kuo-Tung Hsu Kuo-Tung Hsu , Kuo-Liang Chen Kuo-Liang Chen , Hao-Hsiung Lin Hao-Hsiung Lin , Gwo-Jen Jan Gwo-Jen Jan 
Published: October 2002

Using contactless photoreflectance at 300 K we have characterized two InAlAs/InGaAs heterojunction bipolar transistor structures grown by molecular beam epitaxy. The spectra from the InAlAs and InGaAs interface can be accounted for on the basis of a triangular potential well which confined two-dimensional electron gas. A detailed lineshape fit makes it possible to evaluate the Fermi energy, and hence the two-dimensional electron gas concentration. Furthermore, other important parameters of the system, such as built-in electric fields and In composition, can be evaluated.
Temperature Dependence of Band Gap Change in InN and AlN
Authors: Qixin Guo Qixin Guo , Akira Yoshida Akira Yoshida 
Published: October 2002

The optical band gap of InN and AlN single crystal films was measured through absorption spectra in the temperature range of 4.2 to 300 K. The samples were grown on (0001)α-Al2O3 substrates by metalorganic vapor phase epitaxy. The Varshni equation and the Bose-Einstein expression have been compared with the experimental results. The nitride III-V compound semiconductors have smaller temperature dependence of band gap change. In III-V compound semiconductors, the variation of the band gap change increases in the order of N, P and As.
Characteristics of Planar Optical Device Using Acoustooptic Effect
Authors: Yukinori Hatayama Yukinori Hatayama , Yasumitsu Miyazaki Yasumitsu Miyazaki , Nobuo Goto Nobuo Goto 
Published: October 2002

A planar acoustooptic (AO) device composed of two adjacent channel waveguides is proposed and analyzed. The planar AO device is suitable for integrating the devices in the horizontal direction, as compared with vertically coupled AO devices. This planar AO device is useful in optical integrated circuits such as integrated N×N matrix switches. We discuss the coupling process and the efficiency characteristics of the proposed planar AO devices. The required surface acoustic wave (SAW) frequency is 100 MHz at the waveguide separation distance of 0.5 µm.
Characterization of Epitaxially Grown CeO2(110) Layers on Si by Means of Shadowing Pattern Imaging with Fast Ion Beams
Authors: Inoue Tomoyasu , Kudo Hiroshi , Fukusho Taro , Ishihara Toyoyuki , Tetsu Ohsuna Tetsu Ohsuna 
Published: October 2002

Shadowing pattern imaging using keV secondary electrons induced by 56 MeV O8+ ions has been applied to investigate the texture structure of epitaxially grown CeO2(100) layers on Si(100) substrates. The observed shadowing pattern is characteristic of the crystal with a domain structure, i. e., a clear <110> axial image and smeared planar images, which result from the overlapping of two kinds of planar patterns (one is rotated 90° from the other around the <110> axis). The results are consistent with the observations by high-resolution secondary electron microscopy and reflection high-energy electron diffraction.
Surface Acoustic Wave Characteristics on ZnO/\mbYZ·LiNbO 3 Structure and Their Application to Elastic Convolver
Authors: Michio Kadota Michio Kadota , Kunio Minami Kunio Minami 
Published: October 2002

In an effort to improve the efficiency of an elastic convolver, we discussed ways to increase the electromechanical coupling factor of the LiNbO3 (LN) substrate. We examined, both theoretically and experimentally, the surface acoustic wave (SAW) characteristics of ZnO films formed on the +Y· and -Y·planes of the Y
Z·LN substrates. As a result, it was clear that a larger electromechanical coupling factor, k
s, can be obtained with a ZnO film on the +Y·plane than on the -Y·plane of Y
Z·LN substrates. The maximum value of the coupling factor obtained was 0.32, which was 2.04 times the square (k
s
2) of the value obtained without the ZnO film. By applying the LN substrate with the ZnO film on its +Y·plane to the elastic convolver, we obtained a processing time of 7.6 µs, a 3 dB bandwidth of 44 MHz and an efficiency of -58 dBm.
Optical Mode Conversion by Magnetostatic Surface Waves in Optical Waveguide-Type Devices Using Cerium- and Bismuth-Doped Garnet Crystalline Films
Authors: Shin'ichiro Kikuchi Shin'ichiro Kikuchi , Yasumitsu Miyazaki Yasumitsu Miyazaki 
Published: October 2002

Optical devices using magnetostatic surface waves (MSSWs) have important applications in optical signal processing and optical computing. In this paper we propose the analysis and design of an optical mode conversion device that features improved switching efficiency achieved by the use of a new material with increased magneto-optic effect. The device consists of cerium- and bismuth-doped thin and thick garnet films. The design features 100% mode conversion over an interaction length of about 5 mm for an applied microwave power density in the range 1–10 mW/mm. Cerium- and bismuth-doped Yttrium Iron Garnet (YIG) films are fabricated by rf sputtering and their crystal properties are studied using X-ray microanalyzer and X-ray diffractometer.
Observation of Tunneling Electron Luminescence at Low Temperatures Using Novel Conductive Transparent Tip
Authors: Tooru Murashita Tooru Murashita , Masafumi Tanimoto Masafumi Tanimoto 
Published: October 2002

A novel conductive transparent (CT) tip has been developed that effectively collects tunneling-electron luminescence with a large solid angle of 2 sr in the direction of the most intensive photoemission. Using this CT tip, the spectrum of tunneling-electron luminescence from cleaved Zn-doped GaAs was obtained at 10 K.
Quantum Well Wire Fabrication Method Using Self-Organized Multiatomic Steps on Vicinal (001) GaAs Surfaces by Metalorganic Vapor Phase Epitaxy
Authors: Shinjiroh Hara Shinjiroh Hara , Junichi Motohisa Junichi Motohisa , Takashi Fukui Takashi Fukui , Hideki Hasegawa Hideki Hasegawa 
Published: October 2002

Coherent multiatomic steps with extremely straight edges are naturally formed on vicinal (001) GaAs surfaces during metalorganic vapor phase epitaxial growth. GaAs quantum well wires (QWWs) are formed on these self-organized multiatomic steps. In our previous study, a thin AlGaAs layer was grown on GaAs with multiatomic steps as a lower barrier of QWWs. However, the height and spacing of the steps slightly fluctuate on AlGaAs layer surfaces. Therefore, in this experiment, AlAs layer instead of AlGaAs layer was used as a lower barrier layer to improve the uniformity of the height and spacing of the steps. Atomic force microscopy observations and photoluminescence (PL) measurements at 20 K revealed that the underlying coherent GaAs multiatomic steps were well traced by the AlAs barrier layer rather than the AlGaAs barrier layer. Furthermore, we measured the polarization anisotropy of the PL spectra from the QWWs with AlAs. These results suggest that uniform QWWs are successfully formed using multiatomic steps on vicinal (001) GaAs surfaces.
Observation of 77 K Staircase I-V Characteristics in 2DEG's Irradiated by a Focused Ion Beam
Authors: Sung Woo Hwang Sung Woo Hwang , Henri Lezec Henri Lezec , Toshitsugu Sakamoto Toshitsugu Sakamoto , Kazuo Nakamura Kazuo Nakamura 
Published: October 2002

Staircase current-voltage (I-V) characteristics, observed at 77 K in narrow 2DEG channels irradiated by a single line scan of a focused ion beam (FIB), is reported in detail. These staircases are interpreted as evidence of single electron tunneling through a naturally occurring specific Coulomb island in the random potential fluctuations created by FIB damage. Clear comparison is made between the I-V's taken from wide channels and those from narrow channels. Based on orthodox calculations of the I-V characteristics, it is shown that highly asymmetric tunnel junctions are needed to explain our data. This is consistent with the random nature of the potential landscape in the FIB damaged region.
Nanostructure Alignment for Hot Electron Interference/Diffraction Devices
Authors: Hiroo Hongo Hiroo Hongo , Jun Suzuki Jun Suzuki , Michihiko Suhara Michihiko Suhara , Yasuyuki Miyamoto Yasuyuki Miyamoto , Kazuhito Furuya Kazuhito Furuya 
Published: October 2002

An ultrafine fabrication technique for hot electron interference/diffraction devices was developed. The alignment of two nanostructures by e-beam direct writing before and after crystal growth was reported for the first time. The aligned structure consists of 70 nm pitch grating GaInAs/InP buried structure and 70 nm pitch stripe electrode of Cr/Au.
Physical Properties of Bi 4Ti 3O 12 Films Grown on Si(100) Wafers
Authors: Masaki Yamaguchi Masaki Yamaguchi , Takao Nagatomo Takao Nagatomo , Osamu Omoto Osamu Omoto 
Published: October 2002

Bismuth titanate (Bi4Ti3O12) films were prepared on Si(100) wafers by rf planar magnetron sputtering using a target of Bi2TiO5 ceramic. C-axis-oriented Bi4Ti3O12 films were grown on Si(100) at a low substrate temperature of 550°C. However, these films did not exhibit ferroelectricity, and the dielectric constant ε
r and dissipation factor tan
δ were about 156 and 0.032, respectively. The dielectric constant was reduced with decreasing film thickness. This behavior was assuming supposing a low-dielectric-constant interface layer. These films showed the dielectric breakdown field of about 21 kV/cm.
Pyroelectric Property of Pb 5Ge 3O 11 Thin Films Prepared by Laser Ablation
Authors: Yasuyuki Kageyama Yasuyuki Kageyama , Jiro Sakata Jiro Sakata , Yasunori Taga Yasunori Taga 
Published: October 2002

Pb5Ge3O1
1 films were prepared by laser ablation, and pyroelectricity was obtained in the films after annealing. Stoichiometric films were formed at oxygen pressures around 5×10-1 Torr during deposition. It was found that an unreported precursor phase was grown on Pt/Ti/SiO2/Si substrates at a temperature of 520°C. Subsequent annealing at 500°C for 2 h in air made it possible for the film to have (001) oriented texture of ferroelectric Pb5Ge3O1
1. This sample showed remanent polarization of 1.4 µC/cm2 with a ferroelectric hysteresis loop of an asymmetric shape and a pyroelectric coefficient of 4.3 nC/cm2K, while these values were about one third of those reported for single crystal Pb5Ge3O1
1 in a polarization direction. The inferiority in this ferroelectricity is thought due to the lead-deficient phase involved in the film. Although this localized second phase still remains, the appreciable reduction in the process temperature for texturing a Pb5Ge3O1
1 film in the c-plane as low as around 500°C is attributed to the sufficient supply of oxygen during the deposition.
Propagation Characteristics of Leaky Surface Acoustic Waves and Surface Acoustic Waves on LiNbO 3 Substrates with a Ferrroelectric Inversion Layer
Authors: Kiyoshi Nakamura Kiyoshi Nakamura , Ailie Tourlog Ailie Tourlog 
Published: October 2002

The propagation characteristics of the leaky surface acoustic wave (LSAW) propagating on rotated Y-X lithium niobate (LiNbO3) substrates with a ferroelectric inversion layer are theoretically analyzed. The results show that the attenuation of the LSAW on 41° Y-X LiNbO3 is smaller than 10-5 dB/wavelength over a range of k
h (k: wave number, h: inversion-layer thickness) from 2 to 2.5 for both free- and metallized-surface cases, and that the phase velocity of the LSAW is decreased and the concentration of the displacement to the surface is improved by the electric-field short-circuiting effect of the domain boundary. The propagation characteristics of the surface acoustic wave on 128° Y-X LiNbO3 substrates with an inversion layer are also reported.
A New Technology for Negative Ion Detection and the Rapid Electron Cooling in a Pulsed High-Density Etching Plasma
Authors: Tae Hyuk Ahn Tae Hyuk Ahn , Keiji Nakamura Keiji Nakamura , Hideo Sugai Hideo Sugai 
Published: October 2002

Time-resolved measurements of key parameters in an inductively-coupled pulsed discharge in chlorine are carried out to elucidate a feature of pulsed plasma etching. Langmuir probe diagnostics in the afterglow phase show a very fast decrease in the electron temperature from 3.5 eV to 0.8 eV within 10 µs, along with a plasma potential drop from 22 V to 5 V. A new technique for measuring the time-varying absolute negative ion density is developed, which is based on laser-induced photodetachment and electron-beam excited instabilities at plasma frequency. This novel method reveals that the dissociative electron attachment yields a large increase in the chlorine negative ion density of up to 2×1010 cm-3 (∼50 % of the positive ion density) at an afterglow time of 20 µs.
Thickness Dependence of H Radical Treatment of Si Thin Films Deposited by Plasma-Enhanced Chemical Vapor Deposition Using SiF4/SiH4/H2 Gases
Authors: Tatsuru Shirafuji Tatsuru Shirafuji , Hisao Kondo Hisao Kondo , Kunihide Tachibana Kunihide Tachibana 
Published: October 2002

Thickness dependence of H radical treatment of silicon thin films deposited using SiH4/H2 and SiF4/SiH4/H2 plasmas has been investigated. In both cases, H radicals have caused etching and crystallization. In the case of films less than 60 Å thick, almost pure etching occurred. In the case of films more than 600 Å thick, a crystallized layer under a roughened layer remained after etching. These results indicate that crystallization effect occurs in deeper layers than those in which etching occurs.
Direct Observation of Poly(macromonomer) by Scanning Tunneling Microscopy*1
Authors: Shin-ichi Unayama Shin-ichi Unayama , Ken Nakajima Ken Nakajima , Takayuki Ikehara Takayuki Ikehara , Toshio Nishi Toshio Nishi , Yasuhisa Tsukahara Yasuhisa Tsukahara 
Published: October 2002

Direct observation of a single molecule of poly(macromonomer) adsorbed on a highly oriented pyrolytic graphite was carried out by scanning tunneling microscopy (STM). The poly(macromonomer) studied is multibranched polystyrene possessing very dense polystyrene side chains of uniform molecular weight, which was prepared by polymerization of polystyrene macromonomers. It was revealed that the polystyrene side chains of the poly(macromonomer) extended from the main chain and were observed as an array of parallel lines on the graphite. The interval between the side chains was estimated as 0.42±0.03 nm. This value indicates that the main chain does not have an all-trans conformation but a TG+TG- conformation of the staggered model with alternate arrangement of the side chains, although the main chain is highly extended. We also observed an intramolecular structure, i.e., phenyl groups in the side chain. The distance between the two nearest-neighbor phenyl groups in the same side chain was observed as approximately 0.30 nm, indicating that each side chain is adsorbed on the graphite surface with strong intra- and intermolecular interactions. It was also confirmed by STM that the polymerization of macromonomers took place to form poly(macromonomer) in spite of the extremely high segment density.
Impedance Measurement for Various Vacuum Components in Pohang Light Source Storage Ring
Authors: Dae-Hyun Han Dae-Hyun Han , M. Kwon M. Kwon , Young-Soo Kim Young-Soo Kim 
Published: October 2002

The Pohang Light Source (PLS) is a 2 GeV, third-generation synchrotron light source which was recently commissioned. Loss factor measurements were carried out for various storage ring vacuum components using the synthetic pulse technique. The measurement was done for bunch lengths (σ
l
) ranging from 7.1 to 30 mm. The measured devices were elliptical and circular photon masks, bellows with elliptical and circular cross sections, ellipse-to-diamond transition, ellipse-to-ellipse transition, beam position monitor chamber, and circular T-piece. Broad-band impedances were obtained by fitting the measured loss factors to broad-band resonator model. The total broad-band impedance of 250 devices was 0.17 \ohm, which is a small fraction of the total machine impedance budget as expected in the calculation.
Sol–Gel Transition in Gelatin Observed with Surface Waves
Authors: Hisashi Takahashi Hisashi Takahashi , Pak-Kon Choi Pak-Kon Choi 
Published: October 2002

Surface wave velocity and absorption were measured in the frequency range 250–750 Hz in gelatin solution at around the sol–gel transition temperature. We propose a dispersion relation for surface wave propagation on gel, which takes surface tension and viscoelasticity into account. The results obtained using the dispersion relation provide the shear elasticity and viscosity in the gelation process. The shear elasticity and viscosity were interpreted within the framework of the percolation theory. The critical exponents obtained experimentallyt=1.7–2.2 ands=0.7–0.8 are in good agreement with the percolation theory.
Measurement of Vibration at a Surface Using an Ultrasonic Probe
Authors: Naoto Wakatsuki Naoto Wakatsuki , Koichi Mizutani Koichi Mizutani , Keinosuke Nagai Keinosuke Nagai 
Published: October 2002

We propose a contact ultrasonic probe which can distinguish between longitudinal and transverse vibrations. In contrast to a probe which uses a convergent beam, our probe has resolution which is not limited by the wavelength, so it has high resolution even at low frequencies. It is experimentally confirmed that the probe can discriminate longitudinal and transverse vibrations and that it has resolution higher than about 4 mm which is the wavelength of a carrier wave around 1 MHz.
Acoustic Imaging for Archaeological Investigations Using Wavelet Transform
Authors: Hiroyuki Hachiya Hiroyuki Hachiya , Yukinori Amao Yukinori Amao 
Published: October 2002

Recently, scientific methods such as acoustical survey or ground radar, have been used in the survey of buried remnants. Archaeological cultural property is often buried at a shallow depth of about 1 to 5 m. In the configuration presented here, we receive various waves, such as the direct wave along the surface, longitudinal wave and transverse wave, at almost the same time. In this paper, we propose a processing technique using the wavelet transform to separate the desired signal. From a survey experiment at the test site, it was found that this processing technique is useful for the reconstruction of underground images for archaeological investigations.
Scanning Tunneling Microscope Studies on Recovery Processes of Sputter-Induced Surface Defects on Si(111)-7×7
Authors: Kazuya Yoneyama Kazuya Yoneyama , Keiichi Ogawa Keiichi Ogawa 
Published: October 2002

Vacant regions have been introduced onto the Si(111)-7×7 surface by 1 keV Ar ion bombardment and studied by scanning tunneling microscopy. The vacant regions are defect regions where adatoms have been removed by Ar ion impact. When annealed at temperatures from 500°C to 730°C, the vacant regions recover the initial 7×7 structure via the new metastable 7×7 structure found in the present study. Both rate-controlling steps are described by single activation free energies with dominant -TΔS and minor ΔE terms. The activation entropies ΔS/(eV K-1) are found to be - 1.9 ×10-3 for the metastable 7×7 formation and -2.6×10-3 for the stable 7×7 formation.
Calibration of the Stark-Broadening Parameters of Two	He I Lines with Forbidden Components
Authors: Pérez C. , Rosa I. de la , Aparicio J. A. , S. Mar S. Mar , M. A. Gigosos M. A. Gigosos 
Published: October 2002

Measurements of the Stark-broadening parameters of two \HeI	lines with forbidden components, have been done in a pulsed arc plasma.	Electron density, ranging from 1.50×1022 to	1.45×1023 m-3, is obtained by the interferometry of two	wavelengths. Plasma temperature, determinated by Boltzmann plots	of several \HeIlines, lies in the interval 16 000–25 000 K.	A set of four geometrical profile parameters are obtained	and compared with previous experimental and theoretical results.	The empirical formulae proposed in this paper can be used in plasma	diagnostics.
Investigation of Buffer Iayer of Cubic GaN Epitaxial Films on (100) GaAs Grown by Metalorganic-Hydrogen Chloride Vapor-Phase Epitaxy
Authors: Miura Yoshiki , Takahashi Naoyuki , Akinori Koukitu Akinori Koukitu , Hisashi Seki Hisashi Seki 
Published: October 2002

Cubic GaN epitaxial layers are grown with GaN buffer layers of various thicknesses on (100) GaAs substrate using (CH3)3Ga, HCI and NH3 as starting materials. The full width at half-maximum (FWHM) of the X-ray peak, the surface roughness and the PL spectra show that the optimum thickness of the GaN buffer layer ranges from 20 to 50 nm. It is found by high-resolution TEM and electron diffraction measurements that a GaN buffer layer grown at 500° C is a polycrystal and becomes a single crystal upon thermal annealing at 850° C for 10 min prior to the growth of a cubic GaN epitaxial layer.