bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of ultrathin InAs quantum wells by TEM–cathodoluminescence and TEM techniques
Authors: Grillo V. , Genseki A. , Yamamoto N. , Watanabe Y. 
Published: January 2003

AbstractEmission from ultrathin quantum wells of different thicknesses is studied. In particular, for structures with doped substrate the unintentional deposition of Cu droplets is used as a probe of electron diffusion inside the material. A large diffusion length (L = 8 ± 3 µm) is found in spite of the presence of quantum dots. In particular, the contribution to the diffusion from re‐emission of electrons from quantum dots is evaluated. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of 3D atomic structure of surfaces and interfaces by photoelectron holography
Authors: Nihei Yoshimasa 
Published: January 2003

AbstractElectron spectroscopy currently is used not only for electronic state analysis but also for determining the structure of solid surfaces. Photoelectron diffraction is particularly suitable for examining the structure of solid surfaces and interfaces. Moreover, the combination of medium‐energy scanned‐angle photoelectron diffraction and photoelectron holography is a very appealing and effective method for the characterization of epitaxial thin films. This is because the two techniques are based on the use of the same data set—scanned‐angle photoelectron diffraction patterns—to provide different kinds of features.Photoelectron diffraction in the energy region of x‐rays requires a higher angular resolution and a high‐power x‐ray source, especially in high‐performance measurement systems. A new type of instrument equipped with a multi‐energy high‐power x‐ray source and high angle‐resolving analyser has been developed. Application of this instrument to atomic‐level characterization of some kinds of nanomaterial systems is currently in progress. Copyright © 2003 John Wiley & Sons, Ltd.
Phase reconstruction with simultaneous correction of spherical and astigmatic aberrations by three‐dimensional Fourier filtering method
Authors: Kawasaki Tadahiro , Takai Yoshizo 
Published: January 2003

AbstractA phase reconstruction technique in transmission electron microscopy (TEM), called the three‐dimensional Fourier filtering method (3D‐FFM), was extended to simultaneous correction of spherical aberration and twofold astigmatism. The effect of the aberration correction was confirmed experimentally for a wide spatial frequency range in the corrected through‐focus images of an amorphous thin film. As an application of this method, the surface structure of a gold nanoparticle was observed. The aberration‐free phase image clearly reconstructed the atomic missing‐row structure at the edge of the particle. Copyright © 2003 John Wiley & Sons, Ltd.
Aberration‐free images observed with TEM and STEM
Authors: Shimizu R. 
Published: January 2003

AbstractA defocus image modulation processing (DIMP) technique was verified successfully with the JSPS (Japan Society for the Promotion of Science) Super Electron Microscope that was developed in a 5‐year (1996–2001) project called ‘Development of Super Electron Microscope in Next Generation’ under the JSPS Research for the Future programme (RFTF). This novel DIMP‐transmission electron microscope (DIMP‐TEM) is commercially available as the first phase‐contrast electron microscope. The DIMP‐TEM enables aberration‐free images of the selected phase contrast or amplitude contrast to be observed on cathode ray tubes in real time (2/30 s), leading to dynamic observation of events such as migration of a single atom on a surface as well as unstained biological specimens, where a low phase contrast is an inherent part of their images.The situation regarding scanning transmission electron microscopes (STEMs) is more favourable from a technical point of view, although this has yet to be recognized. According to the reciprocity theorem, any aberration‐free imaging technique for TEMs should be, in principle, applicable to STEMs. A DIMP‐STEM would enable us to extract aberration‐free scan images observed with an ideal electron probe and obtained by an aberration‐free electron optical system.This paper reviews recent advances in DIMP‐TEMs and presents a proposal for a novel DIMP‐STEM. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of high‐precision phase‐shifting electron holography by using hologram simulation
Authors: Yamamoto Kazuo , Hirayama Tsukasa , Tanji Takayoshi , Hibino Michio 
Published: January 2003

AbstractIn phase‐shifting electron holography, Fresnel diffraction at an electron biprism introduces distortions to the amplitude and phase of the electron waves, which cause phase errors in the reconstructed phase images. To reduce the phase errors, two correction methods have been proposed, termed Fresnel corrections. In order to evaluate the phase‐shifting electron holography with Fresnel corrections, we faithfully simulated holograms by considering the influence of Fresnel diffraction, the quantum noise and the electron wave coherency, and then compared the phase images reconstructed from corrected and uncorrected holograms. We found that the phase error due to Fresnel diffraction was reduced to 1/20 by using Fresnel corrections, and that the phase measurement precision reached 2π/410 rad. We are able to observe the weak electric field due to positive charges corresponding to five electrons. Copyright © 2003 John Wiley & Sons, Ltd.
Real‐time observation of surface morphology at nanometer scale using x‐ray specular reflection
Authors: Kawamura T. , Watanabe Y. , Fujikawa S. , Bhunia S. , Uchida K. , Matsui J. , Kagoshima Y. , Tsusaka Y. 
Published: January 2003

AbstractThe changes of surface morphology at nanometer scale during metal–organic vapour‐phase epitaxial growth of indium phosphide have been investigated by using x‐ray specular reflection at grazing incidence. At the low growth temperature of 400°C, large decreases of x‐ray beam intensity were observed, suggesting the formation of nanometer‐sized nuclei. At a higher growth temperature of 500°C, oscillations estimated to by layer‐by‐layer growth were observed, and roughness changes obtained from these oscillations were <0.01 nm, suggesting small‐island formation on the terrace or step‐edge fluctuation during the growth. Additionally, reflectivity increases at a growth temperature of 550°C were observed. Considering the reflectivity dependence on t‐butylphosphine flow at 400°C, the change of reflectivity at 550°C is explained by the existence of phosphorus layers before the growth. Copyright © 2003 John Wiley & Sons, Ltd.
X‐ray reflection from thin multilayers: symmetric patterns
Authors: Karimov Pavel , Harada Shingo , Kawai Jun 
Published: January 2003

AbstractA series of experiments on x‐ray reflection from thin multilayers and films on a silicon wafer were carried out. The x‐ray source and detector were fixed and the glancing angle was changed by sample stage rotation. The use of a Geiger‐Müller counter allowed bizarre symmetric patterns to be obtained in the reflected x‐ray intensity. The origin of these patterns is not clear at the present stage of the investigation.To perform a preliminary analysis of the x‐ray reflection from multilayers, the Microsoft Access database has been developed. Copyright © 2003 John Wiley & Sons, Ltd.
Atomic structure of Si(113) surface studied by coaxial impact collision ion scattering spectroscopy
Authors: Kim K. S. , Choi J. U. , Cho Y. J. , Kang H. J. 
Published: January 2003

AbstractThe atomic structure of Si(113) has been studied by using time‐of‐flight coaxial impact collision ion scattering spectroscopy (ToF‐CAICISS) and reflection high‐energy electron diffraction (RHEED). The RHEED observations showed two ordered phases of 3 × 2 and 3 × 1. A phase transition of 3 × 2 to 3 × 1 was observed to occur reversibly in a temperature range of 450–550°C. From the CAICISS measurements, it was found that the intensity variations of the 3 × 2 phase are most probably consistent with the 3 × 1 phase and they are almost symmetric on [332], suggesting a geometrical similarity in the local atomic structure between the two reconstructions. It turned out that two reconstructions have top surface atoms with arrangement along [110], probably forming a unit of five atoms having a dimer as in previously reported structural models. The interatomic distance or bond length between the top surface atoms was determined. In particular, it was found that the dimer is positioned slightly lower than the other two top surface atoms. From these results, the atomic structure of Si(113) is discussed on the basis of previously reported structural models, including the unit of five atoms and the adatoms. Copyright © 2003 John Wiley & Sons, Ltd.
Monte Carlo study of the spin polarization enhancement in the low‐energy secondary electron emission from ferromagnetic materials
Authors: Yasuda Masaaki , Katsuse Ryuhei , Kawata Hiroaki , Murata Kenji 
Published: January 2003

AbstractThe spin polarization enhancement of secondary electrons emitted from ferromagnetic materials at low kinetic energies is studied by a Monte Carlo simulation of electron scattering that considers the spin direction of generated secondary electrons. A modified model of electron scattering in the magnetic materials is proposed that introduces electron–hole pair excitation processes with opposite spin (Stoner excitations). The two major characteristics—the primary energy dependence and the spectrum of secondary electron spin polarization—are studied with both the previous and the modified simulation models. A better agreement with experimental measurements is obtained in both characteristics with the modified model. The enhancement of the secondary spin polarization at low energies is reproduced by the introduction of Stoner excitation processes into the simulation. Copyright © 2003 John Wiley & Sons, Ltd.
Surface morphology and interface structural analyses of Ti(film)/SiC(substrate) by PEEM, SXES, AES and XRD
Authors: Labis Joselito , Ohi Akihiko , Hirai Masaaki , Kusaka Masahiko , Iwami Motohiro 
Published: January 2003

AbstractA spectro‐microscopy study has been conducted on the Ti(film)/SiC(substrate) system. The variation in surface morphology of a heat‐treated Ti film on SiC was analysed by x‐ray photoemission electron microscopy (PEEM) and Auger electron spectroscopy (AES), whereas the interfacial reaction was characterized by synchrotron radiation‐induced soft x‐ray emission spectroscopy (SXES) and x‐ray diffraction (XRD). The formation of structures was observed on the Ti surface on 3C–SiC substrates at ∼850°C. The AES analysis on Ti/3C–SiC samples heated from 600°C to 900°C revealed an Si‐rich surface. The SXES and XRD characterizations on the structure of the interface have revealed the formation of Ti5Si3 and TiC as the dominant reaction products. Copyright © 2003 John Wiley & Sons, Ltd.
Imaging micropatterned organosilane self‐assembled monolayers on silicon by means of scanning electron microscopy and Kelvin probe force microscopy
Authors: Wu Yunying , Hayashi Kazuyuki , Saito Nagahiro , Sugimura Hiroyuki , Takai Osamu 
Published: January 2003

AbstractField‐emission scanning electron microscopy (FE‐SEM) and surface potentiometry based on scanning probe microscopy, i.e. Kelvin probe force microscopy (KFM), have been applied to study microstructures consisting of organosilane self‐assembled monolayers (SAMs) terminated with ‐CH3 or ‐CF3 groups. Onto cleaned Si substrates covered with a thin oxide layer of 2 nm thick, SAMs were formed by chemical vapour deposition using n‐octadecyltrimethoxysilane (CH3(CH2)17Si(OCH3)3, ODS) or fluoroalkylsilane (CF3(CF2)7(CH2)2Si(OCH3)3, FAS) as a precursor. Through a photolithographic technique employing vacuum ultraviolet light at 172 nm, microstructures composed of ODS, FAS or both were fabricated. Micropatterns of the SAMs on SiO2/Si substrates were clearly imaged by FE‐SEM at an acceleration voltage of the electron beam below 1 kV, but image contrasts became faint with an increase in the acceleration voltage. At a voltage of 5 kV there was almost no detectable contrast. An FE‐SEM image of the ODS–FAS microstructure acquired at an acceleration voltage of 0.8 kV clearly demonstrated that the region covered with ODS was brighter and thus, emitted secondary electrons more efficiently than the region covered with FAS. Furthermore, as indicated in a KFM image, the region covered with FAS had a surface potential ∼180 mV lower than that of the region covered with ODS. The origin of these image contrasts between ODS‐ and FAS‐SAMs was the large difference in electronic states between ODS and FAS owing to the electron negativity of fluorine atoms. Copyright © 2003 John Wiley & Sons, Ltd.
AFM observation of nanosized SiC dots prepared by ion beam deposition
Authors: Xu Y. , Narumi K. , Miyashita K. , Naramoto H. 
Published: January 2003

AbstractNanosized silicon carbide (SiC) dots are grown by low‐energy mass‐selected ion beam deposition (MSIBD) on 4°‐off Si(111) substrates at temperatures of 800–950°C and examined by atomic force microscopy (AFM). We find that the size distribution and the geometrical arrangement of SiC dots strongly depend on the substrate temperature, i.e. highly uniform SiC dots are formed at 800°C and 850°C; in particular, SiC dots are arranged in lines when the deposition temperature is as low as 800°C. These results indicate that self‐assembled SiC dots can be prepared on misoriented substrates at low deposition temperatures. Copyright © 2003 John Wiley & Sons, Ltd.
Ab initio molecular orbital calculation for hydrogen‐induced states of titanium (III)
Authors: Hayashi Kazuya , Nakagawa Sachiko T. , Mizuno Yoshiyuki , Tanaka Akihiro , Homma Teiichi 
Published: January 2003

AbstractWhen titanium (Ti) metal absorbs a lot of hydrogen, the XPS spectrum shows a remarkable change in the valence band. Making use of molecular orbital (MO) calculations, we ascribed the peak shift to the formation of a hydrogen‐induced state of Ti. The trapped site of hydrogen in Ti may be at the lattice point in titanium hydride (TiH2), which forms a polycrystal with the small Ti crystals. Copyright © 2003 John Wiley & Sons, Ltd.
Distribution of lattice parameters in strain‐compensated MQW laser diodes
Authors: Seo Satoru , Matsuda Takeyoshi , Mitose Kengo , Iwase Fusako 
Published: January 2003

AbstractWe have developed a lattice image analysis method that gives lattice parameters directly from the lattice image of multiple quantum well (MQW) laser diodes, in order to judge whether the strain‐compensated structure is adopted or not. The method can handle a large amount of image data. The noise element in the lattice image is removed when the one‐dimensional Fourier transform is applied, and the lattice parameter value is obtained with good precision and good accuracy. The distribution of lattice parameters is valuable for evaluating the structure. Copyright © 2003 John Wiley & Sons, Ltd.
Coherent electron emission from carbon nanotubes: asymmetric young's interference fringes
Authors: Yamashita T. , Matsuda K. , Kona T. , Mogami Y. , Komaki M. , Murata Y. , Oshima C. 
Published: January 2003

AbstractWe have calculated the Young's interference of two electron beams that are asymmetrical about the emission current and/or emission area and compared them with the experimental results of field emission patterns from multi‐walled carbon nanotubes. Most of the fringes observed from the clean surface were similar to those produced with the symmetric slit system, which corresponds to the fact that asymmetry in intensity does not change the fringe shape. In addition, no interference fringes of the two asymmetrical beams about the area were detected. Molecular chemisorption enhanced the emission current at an emission site, but the electron waves were incoherent to the others. Copyright © 2003 John Wiley & Sons, Ltd.
Structural characterization of C60 nanowhiskers formed by the liquid/liquid interfacial precipitation method
Authors: Miyazawa K. , Kuwasaki Y. , Hamamoto K. , Nagata S. , Obayashi A. , Kuwabara M. 
Published: January 2003

AbstractThe structure of C60 whiskers fabricated by using the liquid/liquid interfacial precipitation method is analysed with transmission electron microscopy (TEM). The C60 whiskers with submicrometre diameters, named ‘C60 nanowhiskers (C60NWs)’, contain (002)c planar faults, and the centre‐to‐centre distance between the C60 molecules along the growth axis of C60NWs is shortened ∼1% compared with that of pristine C60 crystals, indicating the formation of chemical bondings between the C60 molecules along [110]c ([100]t) close‐packed directions of the C60NWs. The electrical resistivity of C60 whiskers decreased on decreasing their diameter. This result suggests that the C60NWs are electrically conductive. The C60 whiskers are very flexible and could form a semicircle with a curvature radius of 38 µm. Copyright © 2003 John Wiley & Sons, Ltd.
Marginal versus joint Box–Cox transformation with applications to percentile curve construction for IgG subclasses and blood pressures
Authors: He Xuming , Ng K. W. , Shi Jian 
Published: January 2003

AbstractWhen age‐specific percentile curves are constructed for several correlated variables, the marginal method of handling one variable at a time has typically been used. We address the question, frequently asked by practitioners, of whether we can achieve efficiency gains by joint estimation. We focus on a simple but common method of Box–Cox transformation and assess the statistical impact of a joint transformation to multivariate normality on the percentile curve estimation for correlated variables. We find that there is little gain from the joint transformation for estimating percentiles around the median but a noticeable reduction in variances is possible for estimating extreme percentiles that are usually of main interest in medical and biological applications. Our study is motivated by problems in constructing percentile charts for IgG subclasses of children and for blood pressures in adult populations, both of which are discussed in the paper as examples, and yet our general findings are applicable to a wide range of other problems. Copyright © 2003 John Wiley & Sons, Ltd.
Viral load detectability profiles for HIV infection
Authors: McKinnon Elizabeth J. , James Ian R. , John Mina , Mallal Simon A. 
Published: January 2003

AbstractThe introduction of potent antiretroviral therapies for treatment of HIV infection typically results in a dramatic reduction in plasma HIV RNA concentration, often to levels undetectable by current measurement practices. However, although a high proportion of patients achieve ‘undetectability’, many then experience a return to a state of detectability at a later date. As evaluation of virologic response provides a useful measure of therapy efficacy, it is of interest to estimate the proportions of cases with undetectable viral load over time following commencement of treatment. These proportions depend on the rates of transition from detectability to undetectability and subsequent return to detectability, and may be related to covariates or risk factors, possibly differing in both transitions. We consider construction of detectability profiles as estimates of these proportions, based on parametric modelling of the component survival distributions. The method is applied to an examination of the effects of baseline CD4 T‐cell lymphocyte counts on virologic response to therapy amongst patients of the Western Australian HIV Cohort Study. Copyright © 2003 John Wiley & Sons, Ltd.
Inference for a linear regression model with an interval‐censored covariate
Authors: Gómez Guadalupe , Espinal Anna , W. Lagakos Stephen 
Published: January 2003

AbstractInterval‐censored observations of a response variable are a common occurrence in medical studies, and usually result when the response is the elapsed time until some event whose occurrence is periodically monitored. In this paper we consider a multivariate regression setting in which the explanatory variable is interval censored. Use of anad hocmethod of analysis for such data, such as taking the midpoint of the interval‐censored covariate and applying ordinary least‐squares, is not in general valid. We develop a likelihood approach, together with a two‐step conditional algorithm, to jointly estimate the regression coefficients as well as the marginal distribution of the covariate. The resulting estimators are asymptotically normal. The performance of the method is assessed via simulations, and illustrated using data from a recent HIV/AIDS clinical trial to assess the association between waiting time between indinavir failure and subsequent viral load at enrolment. Extensions of the procedure to other parametric distributions are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Estimating cumulative probabilities from incomplete longitudinal binary responses with application to HIV vaccine trials
Authors: Hudgens Michael G. 
Published: January 2003

AbstractWhen describing longitudinal binary response data, it may be desirable to estimate the cumulative probability of at least one positive response by some time point. For example, in phase I and II human immunodeficiency virus (HIV) vaccine trials, investigators are often interested in the probability of at least one vaccine‐induced CD8+ cytotoxic T‐lymphocyte (CTL) response to HIV proteins at different times over the course of the trial. In this setting, traditional estimates of the cumulative probabilities have been based on observed proportions. We show that if the missing data mechanism is ignorable, the traditional estimator of the cumulative success probabilities is biased and tends to underestimate a candidate vaccine's ability to induce CTL responses. As an alternative, we propose applying standard optimization techniques to obtain maximum likelihood estimates of the response profiles and, in turn, the cumulative probabilities of interest. Comparisons of the empirical and maximum likelihood estimates are investigated using data from simulations and HIV vaccine trials. We conclude that maximum likelihood offers a more accurate method of estimation, which is especially important in the HIV vaccine setting as cumulative CTL responses will likely be used as a key criterion for large scale efficacy trial qualification. Copyright © 2003 John Wiley & Sons, Ltd.
Incremental net benefit in randomized clinical trials with quality‐adjusted survival
Authors: Willan Andrew R. , Bingshu Chen Eric , Cook Richard J. , Lin D. Y. 
Published: January 2003

AbstractOwing to induced dependent censoring, estimating mean costs and quality‐adjusted survival in a cost‐effectiveness comparison of two groups using standard life‐table methods leads to biased results. In this paper we propose methods for estimating the difference in mean costs and the difference in mean effectiveness, together with their respective variances and covariance in the presence of dependent censoring. We consider the situation in which the measure of effectiveness is either the probability of surviving a duration of interest or mean quality‐adjusted survival time over a duration of interest. The methods are illustrated in an example using an incremental net benefit analysis. Copyright © 2003 John Wiley & Sons, Ltd.
A parametric model for long‐term follow‐up data from phase III breast cancer clinical trials
Authors: Jeong Jong‐Hyeon , Jung Sin‐Ho , Wieand Samuel 
Published: January 2003

AbstractWe propose a parametric version of a univariate gamma frailty model. The proposed model is shown to be flexible enough to model long‐term follow‐up survival data from breast cancer clinical trials when the treatment effect diminishes as time progresses, a case for which neither the proportional hazards nor proportional odds assumptions are satisfied. The observed information matrix is computed to evaluate the variances of parameter estimates. A simple parametric test statistic to test proportional odds assumption is also constructed. The model is applied to a data set from a phase III clinical trial on breast cancer. Copyright © 2003 John Wiley & Sons, Ltd.