bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative real‐time PCR technique for rapid prenatal diagnosis of Down syndrome
Authors: Hu Yali , Zheng Mingming , Xu Zhengfeng , Wang Xinru , Cui Hengmi
Published: September 2004

Objectives

To develop a reliable and specific technique for rapid prenatal diagnosis of Down syndrome.

Methods

High throughput real‐time PCR technique was used to measure the DSCR3 gene dosage of genomic DNAs from uncultured amniocytes of fetuses, lymphocytes of trisomy 21 syndrome patients, and normal people, compared to conventional cytogenetic karyotype analysis.

Results

The DSCR3/GAPDH ratio of uncultured amniocytes in trisomy 21 syndrome fetuses to normal fetuses was 1.69 ± 0.17 to 1.06 ± 0.14, respectively (p < 0.001); and the DSCR3/GAPDH ratio of lymphocytes in trisomy 21 syndrome children to normal people was 1.67 ± 0.13 to 0.99 ± 0.10, respectively (p < 0.001). Real‐time PCR technique effectively differentiates the normal fetuses from the trisomy 21 syndrome fetuses; therefore, compared to the results of the conventional cytogenetic karyotype analysis, the DSCR3/GAPDH ratios of trisomy 21 syndrome fetuses are significantly higher than those of normal fetuses.

Conclusion

Because the DSCR3/GAPDH ratio of trisomy 21 syndrome fetuses is significantly higher than that of normal fetuses, the genomic DNA real‐time PCR technique may be a reliable and specific method for the rapid prenatal diagnosis of Down syndrome. Copyright © 2004 John Wiley & Sons, Ltd.
Obstetricians' agreement on fetal prognosis after ultrasound diagnosis of fetal anomalies
Authors: Bijma Hilmar H. , Wildschut Hajo I. J. , van der Heide Agnes , van der Maas Paul J. , Wladimiroff Juriy W.
Published: September 2004

Introduction

After ultrasound diagnosis of a severe fetal anomaly is made, difficult decisions may arise regarding obstetric management. Guidelines have been developed to support obstetricians in decision‐making. However, it is unknown to what extent in the clinical situation, guidelines are actually supportive.

Objectives

We aimed at: (1) determining whether obstetricians in the presence of a fetal anomaly are able to classify fetal prognosis according to guidelines; (2) establishing inter‐ and intra‐observer agreement regarding fetal prognosis.

Methods

We used three categories of fetal prognosis: category 1: the infant has no chance of survival and the abnormalities cannot be treated (1.1); or the infant has a chance of extra‐uterine survival but post‐natal use of life‐prolonging medical treatment is considered futile (1.2); category 2: the infant has a chance of extra‐uterine survival and post‐natal use of life‐prolonging medical treatment, if necessary, is considered beneficial. Five senior obstetricians categorized 100 case descriptions of severe fetal abnormalities, which were classified again after five months.

Results

Four obstetricians were able to classify 98% or more of cases. In 67% of cases, four or all obstetricians agreed on fetal prognosis. The overall kappa coefficient was 0.48 (moderate agreement). The differences between obstetricians represented systematic differences in opinions on how to classify cases. Intra‐observer agreement was 82 to 97%.

Conclusion

Obstetricians were usually able to classify fetal prognosis according to guidelines, but in a substantial number of cases, there was a disagreement reflecting systematic differences between obstetricians. Copyright © 2004 John Wiley & Sons, Ltd.
The cell wall subproteome of Listeria monocytogenes
Authors: Schaumburg Jessica , Diekmann Oliver , Hagendorff Petra , Bergmann Simone , Rohde Manfred , Hammerschmidt Sven , Jänsch Lothar , Wehland Jürgen , Kärst Uwe
Published: September 2004

The surface subproteome of Listeria monocytogenes that includes many proteins already known to be involved in virulence and interaction with host cells has been characterized. A new method for the isolation of a defined surface proteome of low complexity has been established based on serial extraction of proteins by different salts at high concentration, and in all 55 proteins were identified by N‐terminal sequencing and mass spectrometry. About 16% of these proteins are of unknown function and three proteins have no orthologue in the nonpathogenic L. innocua and might be involved in virulence mechanisms. Remarkably, a relatively high number of proteins with a function in the cytoplasmic compartment was identified in this surface proteome. These proteins had neither predicted or detectable signal peptides nor could any modification be observed except removal of the N‐terminal methionine. Enolase (Lmo2455) is one of these proteins. It was shown to be present in the cell wall of the pathogen by immunoelectron microscopy and, along with heat shock factor DnaK (Lmo1473), elongation factor TU (Lmo2653), and glyceraldehyde‐3‐phosphate dehydrogenase (Lmo2459), it was found to be able to bind human plasminogen in overlay blots and surface plasmon resonance (SPR) experiments. The KD values of these interactions were determined by SPR measurements. The data indicate a possible role of these proteins as receptors for human plasminogen on the bacterial cell surface. The potential role of this recruitment of a host protease for extracellular invasion mechanisms is discussed.
Synthesis of rod copolyaramids with short flexible spacers
Authors: Boivin Julie , Brisson Josée
Published: September 2004

Regular rigid‐flexible copolymers composed of aramid segments and aliphatic chains formed of 5 to 10 CH2 groups were synthesized using a two‐stage procedure. A first stage consisted of synthesizing, under Yamasaki–Higashi phosphorylation conditions, poly(paraphenylene terephthalamide) blocks or macromonomers of different lengths by using an excess of phenylene diamine. These macromonomers, with functionalized amine extremities, were reacted in a second stage, using the Higashi phosphorylation conditions, with a terephthalic‐acid end‐capped aliphatic amine. Macromonomer molecular weights and polydispersities were estimated from viscosity and NMR measurements, whereas for block copolymers viscosity measurements and size exclusion chromatography of allylated derivatives were performed. Block polydispersity increased with increasing length of block, but remained below 1.6. Copolymers were found to have Mw values from 2500 to 8600 g mol−1, depending on block length and aliphatic chain used. Polydispersity indices were systematically higher for block copolymers than for macromonomers, with values ranging from 1.6 to 4.7. Mv and Mw were found to be comparable for all copolyaramids, which indicates that addition of short aliphatic chains had a negligible effect on Mark–Houwink parameters. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5098–5112, 2004
Side‐chain cholesteric liquid‐crystalline elastomers derived from smectic crosslinking units: Synthesis and phase behavior
Authors: Hu Jian‐She , Zhang Bao‐Yan , Guan Yan , He Xiao‐Zhi
Published: September 2004

New side‐chain cholesteric liquid‐crystalline elastomers containing cholesteryl 4‐allyloxybenzoate as cholesteric mesogenic units and biphenyl 4,4′‐bis(10‐undecen‐1‐ylenate) as smectic crosslinking units were synthesized. The chemical structures of the olefinic compounds and polymers obtained were confirmed by element analysis, Fourier transform infrared, proton nuclear magnetic resonance, and carbon‐13 nuclear magnetic resonance spectra. The mesogenic properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the concentration of the crosslinking unit on the phase behavior of the elastomers was examined. The elastomers containing less than 17 mol % of the crosslinking units revealed elasticity, reversible mesomorphic phase transition, wider mesophase temperature ranges, and higher thermal stability. The experimental results demonstrated that the glass‐transition temperature, isotropization temperature, and mesophase temperature ranges decreased with an increasing concentation of the crosslinking unit. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5262–5270, 2004
Surface characterization of plasma‐modified poly(ethylene terephthalate) film surfaces
Authors: Inagaki Norihiro , Narushim Kazuo , Tuchida Norio , Miyazaki Kohji
Published: September 2004

Poly(ethylene terephthalate) (PET) film surfaces were modified by argon (Ar), oxygen (O2), hydrogen (H2), nitrogen (N2), and ammonia (NH3) plasmas, and the plasma‐modified PET surfaces were investigated with scanning probe microscopy, contact‐angle measurements, and X‐ray photoelectron spectroscopy to characterize the surfaces. The exposure of the PET film surfaces to the plasmas led to the etching process on the surfaces and to changes in the topography of the surfaces. The etching rate and surface roughness were closely related to what kind of plasma was used and how high the radio frequency (RF) power was that was input into the plasmas. The etching rate was in the order of O2 plasma > H2 plasma > N2 plasma > Ar plasma > NH3 plasma, and the surface roughness was in the order of NH3 plasma > N2 plasma > H2 plasma > Ar plasma > O2 plasma. Heavy etching reactions did not always lead to large increases in the surface roughness. The plasmas also led to changes in the surface properties of the PET surfaces from hydrophobic to hydrophilic; and the contact angle of water on the surfaces decreased. Modification reactions occurring on the PET surfaces depended on what plasma had been used for the modification. The O2, Ar, H2, and N2 plasmas modified mainly CH2 or phenyl rings rather than ester groups in the PET polymer chains to form CO groups. On the other hand, the NH3 plasma modified ester groups to form CO groups. Aging effects of the plasma‐modified PET film surfaces continued as long as 15 days after the modification was finished. The aging effects were related to the movement of CO groups in ester residues toward the topmost layer and to the movement of CO groups away from the topmost layer. Such movement of the CO groups could occur within at least 3 nm from the surface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3727–3740, 2004
Microthermal analysis of the melting behavior in zone‐drawn isotactic polypropylene fibers
Authors: Ye Jiping , Hasegawa T. , Suzuki A.
Published: September 2004

A microthermal analysis (μTA) method with an ultrahigh heating rate was applied to a zone‐drawn isotactic polypropylene fiber to evaluate the melting behaviors inherent to the microstructural changes occurring during the drawing process. The μTA melting point decreased with a reduction in the melting temperature because of the suppression of crystal reorganization and increased with an increase in the melting temperature because of the suppression of the relief of the orientation of the molecular chains, in comparison with the conventional melting point obtained by traditional differential scanning calorimetry. This study examined a convenient and powerful method for investigating the melting behavior for polymeric materials inherent to the original microstructure with less influence from thermal‐measurement heating. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3677–3681, 2004
Adhesive bonding of glassy polymer surfaces by an ultrathin layer of a semicrystalline polymer
Authors: McSwain Rachel L. , Markowitz Alison R. , Shull Kenneth R.
Published: September 2004

To develop a greater understanding of interfacial interactions between a semicrystalline polymer and a glassy polymer, adhesion tests were performed on very thin layers of poly(ethylene oxide) (PEO) sandwiched between two layers of poly(tetramethyl bisphenol A polycarbonate) (TMPC). The tests were designed to provide intimate contact between the surfaces while they were heated above the melting point of the PEO and cooled back to room temperature. A contact mechanics approach, based on the Johnson, Kendall, and Roberts theory, was used to determine values of the energy release rate describing the energetic driving force for crack propagation within the interfacial region. The ability to measure crack propagation at large values of the energy release rate was limited by rupture of the silicone elastomer that was used to provide a sufficiently compliant matrix for the adhesion experiment. By cycling the tensile stress at relatively low loading levels, we were able to measure fatigue crack propagation at values of the energy release rate that did not result in failure of the elastomer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3809–3821, 2004
Hydrophobic Recovery of Vacuum Ultraviolet Irradiated Polyolefin Surfaces
Authors: Truica‐Marasescu Florina , Jedrzejowski Pawel , Wertheimer Michael R.
Published: September 2004

Summary: Film samples of low‐density polyethylene (LDPE) and biaxially oriented poly(propylene) (BOPP) were surface modified by vacuum ultraviolet (VUV) irradiation using a Kr resonant lamp at λ = 123.6 nm in low‐pressure ammonia gas, and were then stored in air. The time‐dependence of the surface properties was monitored using several complementary surface‐sensitive techniques such as contact angle goniometry (CAG), X‐ray photoelectron spectroscopy (XPS), and time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS), which allows one to determine the surface energy, and chemical composition at different depths. The relative importance of four possible mechanisms involved in surface hydrophobic recovery is discussed, and we show that in our particular case the main mechanism is rotational and/or translational motion of polymer chains and chain segments. This restructuring determines the observed “loss” of functional groups, which occurs within the first few monolayers of the surface (∼1 nm), as shown by the ToF‐SIMS results, and which leads to the observed decrease in the surface energy. In the deeper surface regions (∼10 nm) long‐lived radicals react with oxygen and water vapor upon exposure to the atmosphere, leading to an increase in the concentration of bound oxygen, as observed by XPS. Finally, CAG measurements show that the hydrophobic recovery is reversible and can be significantly reduced by cross‐linking near the surface, as illustrated by depth sensing nano‐indentation measurements on BOPP surfaces.

Surface energy, γs, values as a function of storage time for VUV/NH3‐treated a) LDPE (Ed = 14.1 J · cm−2), and b) BOPP samples (Ed = 28.2 J · cm−2). Open symbols pertain to rinsed samples.

magnified image

Surface energy, γs, values as a function of storage time for VUV/NH3‐treated a) LDPE (Ed = 14.1 J · cm−2), and b) BOPP samples (Ed = 28.2 J · cm−2). Open symbols pertain to rinsed samples.
Surface Analysis of Plasma‐Deposited Polymer Films, 3
Authors: Oran Umut , Swaraj Sufal , Friedrich Jörg F. , Unger Wolfgang E. S.
Published: September 2004

Summary: Pulsed‐plasma‐deposited ethylene films were studied by time‐of‐flight static secondary ion mass spectrometry (ToF‐SSIMS) before and after exposure to ambient air. The influence of the external plasma parameters on the secondary ion mass spectra of plasma‐deposited ethylene films was investigated. From these data, information on the chemical character of the plasma‐deposited ethylene films was derived. The investigation of the effect of external plasma parameters on the chemical character of the plasma‐deposited ethylene films revealed that there were some drastic changes in the secondary ion mass spectra of the films. It was found that fragmentation and re‐arrangement of the monomer molecules in the plasma, which affects the chemical character of the deposited films, vary according to the external plasma parameters. When the plasma polymers are exposed to air, extensive oxygen incorporation occurs. The oxygen uptake is high at the beginning and then it levels of. Some indications for the formation and decay of peroxy radicals (COO•) and, subsequently, hydroperoxides (COOH) are found. It was observed that the oxygen uptake of the plasma deposited ethylene films increase when the plasma conditions become harder.

Intensity ratios [m/z 12−/14− (C−/CH)] for plasma‐deposited ethylene samples versus duty cycle. Note that the unsaturated character increases with increasing m/z 12−/14− (C−/CH) intensity ratios.

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Intensity ratios [m/z 12−/14− (C−/CH)] for plasma‐deposited ethylene samples versus duty cycle. Note that the unsaturated character increases with increasing m/z 12−/14− (C−/CH) intensity ratios.
Effects of volumetric ice content and strain rate on shear strength under triaxial conditions for frozen soil samples
Authors: Arenson Lukas U. , Johansen Martha M. , Springman Sarah M.
Published: September 2004

A set of triaxial constant strain rate and constant stress tests was performed on artificially frozen soil samples to study the effect of the volumetric ice fraction, strain rate and also confining stress on the mobilized shear strength. In general, the peak shear strength increased with decreasing volumetric ice content and increasing strain rate. Pure ice samples, however, showed a peak shear strength that was higher than that for those containing about 80% ice by volume for a similar strain rate, although the loss in strength after this maximum was usually much more pronounced, reaching a lower large strain strength than that for frozen sands. The influence of the ice in samples with low ice contents was primarily noticeable at low strains, whereas the large strain behaviour was very similar to that of the unfrozen material. The tests showed the dependency of the mechanical failure and deformation mode of frozen soils on the loading conditions. It could be demonstrated further that large strains have a significant influence on the strength of frozen geo‐materials and therefore efforts should be made to establish in situ strain states when analysing the stability of frozen slopes. Copyright © 2004 John Wiley & Sons, Ltd.
Temperatures in two boreholes at Flüela Pass, Eastern Swiss Alps: the effect of snow redistribution on permafrost distribution patterns in high mountain areas
Authors: Luetschg Martina , Stoeckli Veronika , Lehning Michael , Haeberli Wilfried , Ammann Walter
Published: September 2004

Snow cover distribution strongly affects soil temperatures and, thus, plays a decisive role in determining permafrost distribution patterns. Redistribution of snow by avalanches and snow drift significantly affects the snow‐melt pattern and soil temperatures in steep avalanche slopes of high mountain areas. At Flüela Pass, 2380 m a.s.l., eastern Swiss Alps, the presence and origin of permafrost that occurs at the base of an avalanche‐affected slope below the regional lower limit of discontinuous permafrost was studied by field investigations and numerical simulations. Local permafrost distribution has been determined in former studies by applying geophysical methods and this was confirmed with two boreholes drilled at the slope base and in the avalanche starting zone. Temperature measurements confirm the presence of a 10 m thick permafrost body with temperatures close to the freezing point at the slope base. Numerical simulations of different snow‐cover scenarios for 2002/03 demonstrate the particular effect on soil temperatures of high snow drift accompanying intense snow falls in early winter, controlling the duration of constant zero temperatures at the base of the snow pack at the beginning of the snow period. Copyright © 2004 John Wiley & Sons, Ltd.
Non‐Additivity of Attractive Potentials in Modeling of N2 and Ar Adsorption Isotherms on Graphitized Carbon Black and Porous Carbon by Means of Density Functional Theory
Authors: Ustinov Eugene A. , Do Duong D.
Published: September 2004

We present a new approach accounting for the non‐additivity of attractive parts of solid–fluid and fluid–fluid potentials to improve the quality of the description of nitrogen and argon adsorption isotherms on graphitized carbon black in the framework of non‐local density functional theory. We show that the strong solid–fluid interaction in the first monolayer decreases the fluid–fluid interaction, which prevents the two‐dimensional phase transition to occur. This results in smoother isotherm, which agrees much better with experimental data. In the region of multi‐layer coverage the conventional non‐local density functional theory and grand canonical Monte Carlo simulations are known to over‐predict the amount adsorbed against experimental isotherms. Accounting for the non‐additivity factor decreases the solid–fluid interaction with the increase of intermolecular interactions in the dense adsorbed fluid, preventing the over‐prediction of loading in the region of multi‐layer adsorption. Such an improvement of the non‐local density functional theory allows us to describe experimental nitrogen and argon isotherms on carbon black quite accurately with mean error of 2.5 to 5.8% instead of 17 to 26% in the conventional technique. With this approach, the local isotherms of model pores can be derived, and consequently a more reliable pore size distribution can be obtained. We illustrate this by applying our theory against nitrogen and argon isotherms on a number of activated carbons. The fitting between our model and the data is much better than the conventional NLDFT, suggesting the more reliable PSD obtained with our approach.
New Insights and Characterization Methods Through
Authors: Reichenauer Gudrun
Published: September 2004

Via a sol‐gel process highly porous solids can be synthesized that consist of two homogeneous, isotropically distributed phases, i.e. a pore and a gel backbone phase. This route allows for an independent tuning of the specific surface area and the porosity over a wide range and thus provides model materials for a systematic investigation of complex effects.
Transition of an androgen‐dependent human prostate cancer cell line into an androgen‐independent subline is associated with increased angiogenesis
Authors: Gustavsson Heléne , Welén Karin , Damber Jan‐Erik
Published: September 2004

Background

Androgen‐independent prostate cancer is today an incurable disease, but increased understanding of the mechanisms for the transition into an androgen‐independent state may increase the possibilities for more efficient strategies in the future.

Methods

An androgen‐independent subline, LNCaP‐19, to the androgen‐dependent prostate cancer cell line LNCaP was developed in vitro under standard culture conditions. The characteristics of LNCaP‐19 regarding androgen responsiveness, PSA, and VEGF secretion was studied in vitro. The growth in vivo and the microvessel density (MVD) of the tumors were studied after inoculation in nude mice.

Results

LNCaP‐19 grows equally well in dextran‐charcoal stripped FBS (DCC‐FBS) as in normal FBS, and rapidly gives rise to tumors in both intact and castrated mice, indicating a true androgen‐independent growth. The PSA secretion from LNCaP‐19 cells was lower than from LNCaP cells, while the VEGF level was comparable to the secretion from LNCaP cells without androgen stimulation. The MVD was increased in the LNCaP‐19 tumors, and the vessels also displayed a changed morphology with exclusively small microvessels without lumen.

Conclusions

LNCaP‐19 shows characteristics resembling those of androgen‐independent prostate cancer. An increased MVD and changed vessel morphology in the tumor, makes it an interesting model system for studies regarding angiogenesis in the context of the acquisition of androgen independence. © 2004 Wiley‐Liss, Inc.
Modelling of anti‐HSV activity of lactoferricin analogues using amino acid descriptors
Authors: Jenssen Håvard , Gutteberg Tore J. , Lejon Tore
Published: September 2004

Herpes simplex virus (HSV) causes a number of diseases and new therapies are being pursued vigorously. Earlier studies have shown that modified peptides based on lactoferricins reduce HSV‐1 and HSV‐2 infection, and structure–activity studies indicate that the anti‐viral activity correlates with the binding affinity for heparan sulphate and chondroitin sulphate. In this study it is shown that theoretically derived amino acid descriptors can be used to model the anti‐viral activity of peptides, as well as other peptide properties, even more accurately. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
Growth of bulk GaN on GaN/sapphire templates by a high N2 pressure method
Authors: Boćkowski M. , Grzegory I. , Łucznik B. , Krukowski S. , Wróblewski M. , Kwiatkowski P. , Jasik K. , Wawer W. , Borysiuk J. , Kamler G. , Porowski S.
Published: September 2004

The results of high‐pressure directional growth of GaN on GaN/sapphire templates are presented. The GaN growth rate as a function of the temperature gradient and time is determined. Changes of the growth rate with time are explained. The results of the crystallization process are briefly compared with those obtained for directional growth on pressure‐grown GaN crystals. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence from InGaN/GaN MQWs on sapphire and membranes fabricated by laser lift‐off
Authors: Yu Tongjun , Li Zilan , Qin Z. X. , Chen Z. Z. , Yang Z. J. , Hu X. D. , Zhang G. Y.
Published: September 2004

Photoluminescence and Raman scattering spectra of InGaN/GaN MQWs on sapphire and membranes free of substrate fabricated by laser lift‐off have been studied. It is observed that photoluminescence peak of 850 °C annealed sample red‐shifts from that of as grown sample, while in the case of membrane samples, the luminescence peak blue‐shifts when annealed at 700 °C. In Raman scattering spectra, InGaN/GaN MQWs film without sapphire substrate has a lower E2 mode frequency (569.3 cm–1) than that of the films with substrate (570.8 cm–1), which indicates that compressive stress in the films releases partially when the sapphire substrate is taken off. It is believed that the piezoelectric field decrease leads to the blue‐shift in luminescence spectra. Compared with the samples with sapphire substrate, the free‐standing membranes showed blue‐shift of luminescence peak after relatively low temperature annealing, because the piezoelectric field reduced more easily in the films without substrate. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of InGaN nanorods with indium mole fractions by hydride vapor phase epitaxy
Authors: Kim Hwa‐Mok , Lee Hosang , Kim Suk Il , Ryu Sung Ryong , Kang Tae Won , Chung Kwan Soo
Published: September 2004

This work demonstrates the formation of InGaN nanorod arrays with indium mole fractions by hydride vapor phase epitaxy. The nanorods grown on (0001) sapphire substrates are preferentially oriented in the c‐axis direction. We found that the In mole fractions in the nanorods were linearly increased at x < 0.1. However, In mole fractions were slightly increased at x ≥ 0.1 and then were gradually saturated at x = 0.2. CL spectra show strong emissions from 380 nm (x = 0.04, 3.26 eV) to 470 nm (x = 0.2, 2.64 eV) at room temperature. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MBE growth of Zn‐polar ZnO on MOCVD‐ZnO templates
Authors: Kato Hiroyuki , Sano Michihiro , Miyamoto Kazuhiro , Yao Takafumi , Zhang Bao‐Ping , Wakatsuki Katsuki , Segawa Yusaburo
Published: September 2004

High‐quality Zn‐polar ZnO films were grown on metal‐organic chemical‐vapor deposition (MOCVD) grown ZnO/a‐sapphire templates by plasma‐assisted molecular beam epitaxy (MBE). Annealing of the MOCVD‐ZnO layer in an O2 atmosphere improved the surface roughness and crystallinity of the template. Reflection high‐energy electron diffraction and atomic force microscopy observations revealed that MBE‐ZnO maintained its Zn‐polarity, which is the polarity of the underlying MOCVD‐ZnO, and that the optimized growth condition is the O‐rich flux regime. Structural and optical properties of the MBE‐ZnO films were significantly improved by growth under O‐rich flux condition and introducing a low‐temperature ZnO buffer. The line widths of (0002) and (10 $ \bar 1 $ 0) X‐ray ω‐rocking curves for MBE‐ZnO films were 533 and 582 arcsec, respectively. The ground and excited (n = 2) states of A‐exciton were clearly evident at 3.377 and 3.423 eV in low‐temperature (4.2 K) photoluminescence of the Zn‐polar ZnO film. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of aluminum composition of AlxGa1–xAs in distributed Bragg reflector on surface morphology
Authors: Kim B. , Yoon M. , Kim S. , Son J. , Kim B. , Jhin J. , Byun D.
Published: September 2004

Surface morphology of the AlGaAs/GaAs Vertical Cavity Surface Emitting Laser (VCSEL) grown by metalorganic vapor phase epitaxy (MOVPE) was investigated using atomic force microscopy. It is shown that the morphology of the structure strongly depends on the aluminum composition of the low Al content layer of distributed Bragg reflector (DBR) pairs and epi thickness. Whereas a high Al content layer in DBRs had little effect on the surface morphology, it was attributed that the influence of Al composition on the morphology of AlxGa1–xAs on GaAs was stronger in the range of 0 < x < 0.5 than 0.5 < x < 1. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatially resolved cathodoluminescence study on AlGaN layer fabricated by air‐bridged lateral epitaxial growth
Authors: Ishibashi Akihiko , Kawaguchi Yasutoshi , Sugahara Gaku , Shimamoto Toshitaka , Yokogawa Toshiya , Yamada Yoichi , Ueki Yusuke , Nakamura Kohzo , Taguchi Tsunemasa
Published: September 2004

Structural properties of AlGaN layer on the GaN seed layer fabricated by air‐bridged lateral epitaxial growth (ABLEG) have been studied by spatially resolved cathodoluminescence (CL) microscopy. The cross‐sectional spatially resolved CL images of the ABLEG‐AlGaN layer reveal that there are roughly three regions which have different main CL peaks. This result suggests that there are roughly three regions with the different Al contents. Before coalescence of the overgrown AlGaN wings, there are two regions of Al content, such as about 6.5, 10.6%. On the other hand, after coalescence of the wings, the Al content of the AlGaN layer becomes uniform (Al content = 8.9%). These results suggest that the facet growth of the overgrown AlGaN wings causes the modulation of Al content in the ABLEG‐AlGaN layer. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Emission properties and thermal annealing of InGaN/GaN multiple quantum wells with different protection layers
Authors: Cho H. K. , Park T. E. , Kim D. C. , Shin J. E. , Lee J. S.
Published: September 2004

We investigated the effect of two‐monolayer thick protection layers of GaN and AlGaN at the well growth temperature after the growth of InGaN well in InGaN/GaN MQW structures by MOCVD. The protection layers were very effective in inhibiting the re‐evaporation of indium atoms regardless of the growth of GaN barriers at high temperature from TEM and PL. In addition, the use of GaN barrier grown at high temperature using GaN protection layers improved the emission efficiency due to the growth of high quality GaN without indium desorption. From the thermal treatment of as‐grown samples, the redshift of emission was observed, which was ascribed to the increased quantum confined Stark effect by thermal stress, showing negligible indium gathering and atomic intermixing. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Built‐in electric field at cubic GaN/GaAs(001) heterointerfaces investigated by phase‐selected photoreflectance excitation
Authors: Katayama Ryuji , Onabe Kentaro , Shiraki Yasuhiro
Published: September 2004

The built‐in electric field applied at the cubic GaN/GaAs(001) heterointerfaces and its evolution during the growth process were evaluated using a phase‐selected photoreflectance technique in combination with a variable‐wavelength excitation light, to clarify the origin of the higher‐electric‐field signal observed in the previous photoreflectance study. The spectrum from LT‐GaN/GaAs after 900 °C annealing contains a extremely‐slow signal with a high electric‐field strength and this signal became dominant with decreasing the penetration depth of the modulating light. This confirms the presence of a triangular well just beneath the GaN/GaAs interface regarding the direction of the band‐bending investigated by the previous work, which can be attributed to the parallel‐conduction path ideal for the holes to drift through. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of the phonon‐induced electron transfer between semiconductor bulk and surface states
Authors: Zeiser Andreas , Bücking Norbert , Götte Jörg , Förstner Jens , Hahn Patrick , Schmidt Wolf Gero , Knorr Andreas
Published: September 2004

The coupling of surface and bulk states at semiconductor surfaces through electron–phonon interaction is discussed. The governing equations are derived from a microscopic theory in the framework of the density matrix theory. To gain a first insight, model wave functions are used to simulate the dynamics of nonequilibrium electron distributions in three‐ and two‐dimensional states, coupled by Fröhlich interaction. Typical time scales for the coupling are found to be in the order of few hundreds of femtoseconds. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐frequency vibrational modes of viruses used for nanoelectronic self‐assemblies
Authors: Fonoberov Vladimir A. , Balandin Alexander A.
Published: September 2004

Viruses of cylindrical shape have recently attracted attention as templates for assembly of nanostructured materials and as elements of nanoelectronic circuits. We have calculated the dispersion relations for the lowest vibrational frequencies of the tobacco mosaic virus (TMV) and M13 bacteriophage immersed in air or water. The radial breathing modes of TMV and M13 viruses in air (water) are 1.85 cm–1 and 6.42 cm–1 (2.10 cm–1 and 6.12 cm–1), respectively. Elastic vibrations of the two viruses in water are damped with the quality factor of 3.6 for the radial breathing modes. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Choice of alpha spending function and time points in clinical trials with one or two interim analyses
Authors: Selwyn Murray R. , Fish Susan M.
Published: September 2004

One characterization of group sequential methods uses alpha spending functions to allocate the false positive rate throughout a study. We consider and evaluate several such spending functions as well as the time points of the interim analyses at which they apply. In addition, we evaluate the double triangular test as an alternative procedure that allows for early termination of the trial not only due to efficacy differences between treatments, but also due to lack of such differences. We motivate and illustrate our work by reference to the analysis of survival data from a proposed oncology study.

Such group sequential procedures with one or two interim analyses are only slightly less powerful than fixed sample trials, but provide for the strong possibility of early stopping. Therefore, in all situations where they can practically be applied, we recommend their routine use in clinical trials. The double triangular test provides a suitable alternative to the group sequential procedures in that they do not provide for early stopping with acceptance of the null hypothesis. Again, there is only a modest loss in power relative to fixed sample tests. Copyright © 2004 John Wiley & Sons, Ltd.
The relationship between osteoporotic fracture risk and a surrogate: Apparent discrepancies between analyses based on individual patient data and summary statistics
Authors: Barton Ian
Published: September 2004

There is debate within the osteoporosis research community about the relationship between the risk of osteoporotic fracture and the surrogate measures of fracture risk. Meta‐regression analyses based on summary data have shown a linear relationship between fracture risk and surrogate measures, whereas analyses based on individual patient data (IPD) have shown a nonlinear relationship. We investigated the association between changes in a surrogate measure of fracture incidence, in this case a bone turnover marker for resorption assessed in the three risedronate phase III clinical programmes, and incident osteoporosis‐related fracture risk using regression models based on patient‐level and trial‐level information. The relationship between osteoporosis‐related fracture risk and changes in bone resorption was different when analysed on the basis of IPD than when analysed on the basis of a meta‐analytic approach (i.e., meta‐regression) using summary data (e.g., treatment effect based on treatment group estimates). This inconsistency in our findings was consistent with those in the published literature. Meta‐regression based on summary statistics at the trial level is not expected to reflect causal relationships between a clinical outcome and surrogate measures. Analyses based on IPD make possible a more comprehensive analysis since all relevant data on a patient level are available. Copyright © 2004 John Wiley & Sons Ltd.
Sample sizes for estimation in clinical research
Authors: Julious Steven A. , Patterson Scott D.
Published: September 2004

A sample size justification should be given for all clinical investigations. However, sometimes the objective of a trial is to estimate an effect with a view to planning a later definitive study. This paper describes the calculations for designing studies where one wishes to adopt an estimation approach through using confidence intervals around the overall response. Calculations are given for data anticipated to take a Normal form. Copyright © 2004 John Wiley & Sons, Ltd.
Thermal and Thermo‐mechanical Analysis for Design Evaluation of an Automotive Radar Module
Authors: Lindgren Mats , Belov Ilja , Leisner Peter
Published: September 2004

The influence of the substrate technology, assembly method, and housing material on the thermal, thermo‐mechanical and cost performance of a radar module for automotive applications has been studied to address the product reliability aspects during the design phase. Flip chip and wire bonding have been evaluated for Multi‐Chip Module—Laminate/Deposition (MCM‐L/D) and Multi‐Chip Module—Deposition (MCM‐D) substrate technologies used for electronic packaging solutions in a harsh environment. Solder ball and direct attachment have been investigated as second‐level assembly. As a result of thermal and thermo‐mechanical simulations and cost analysis, radar module designs combining MCM‐D and MCM‐L/D with wire bonding have been revealed, which are preferable for use in different temperature environments with respect to two performance criteria, the maximum junction temperature and the manufacturing cost. Simulation‐based guidelines have been developed for designing radar modules used in automotive applications while satisfying temperature and stress constraints provided for the module. Copyright © 2004 John Wiley & Sons, Ltd.
A theoretical study of the structure and properties of uric acid: A potent antioxidant
Authors: Allen Reeshemah N. , Shukla M. K. , Leszczynski Jerzy
Published: September 2004

A detailed study of tautomeric properties of uric acid, its different anions, and radical species was performed at the DFT level, employing B3LYP functional and the 6‐311++G(d,p) basis set. Single‐point energy calculations were also performed at the MP2 level using B3LYP/6‐311++G(d,p) optimized geometries and the cc‐pVTZ and 6‐311++G(d,p) basis sets. The effect of aqueous solvation on the relative stability of the neutral and anionic species was investigated using Tomasi's polarized continuum model. The keto form of the molecule was found to be the most stable in the gas phase and in aqueous medium. The proton transfer barrier height was also computed. The gas‐phase barrier height is high; however, the inclusion of a water molecule in the proton transfer reaction path reduces the barrier significantly. Among monoanions of uric acid, the species obtained by the deprotonation of the N3 site is the most stable, whereas among dianions, the anion obtained by deprotonation of both N3 and N9 sites is the most stable both in the gas phase and in aqueous medium. It appears that both forms of radicals UAN and UAN would exist. Among radical anions, the species obtained by the dehydrogenation of the N3 site of the N7 anion (the N7 anion was obtained by deprotonation of the N7 site of uric acid) is the most stable in the gas phase and in aqueous solution. The molecular electrostatic potential, ionization potential, and electron affinity are also reported. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Attosecond localization of electrons in molecules
Authors: Bandrauk André D. , Chelkowski Stephane , Nguyen Hong Shon
Published: September 2004

Numerical solutions of the time‐dependent Schrödinger equation for a 1D model non‐Born–Oppenheimer H are used to illustrate the nonlinear nonperturbative response of molecules to intense (I ≥ 1013 W/cm2), ultrashort (t < 10 fs) laser pulses. Molecular high‐order harmonic generation (MHOHG) is shown to be an example of such response and the resulting nonlinear photon emission spectrum is shown to lead to the synthesis of single attosecond (10−18 s) pulses. Application of such ultrashort pulses to the H system results in localized electron wavepackets whose motion can be detected by asymmetry in the photoelectron spectrum generated by a subsequent probe attosecond pulse, thus leading to measurement of electron motion in molecules on the attosecond time scale. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Spindle structure of the stress tensor of chemical bond
Authors: Tachibana Akitomo
Published: September 2004

Covalent bond describes electron pairing in between a pair of atoms and molecules. In the current paper, the space is partitioned in mutually disjoint regions by using new concept of the electronic drop region RD, atmosphere region RA, and the interface S [Tachibana, A. J Chem Phys 2001, 115, 3497]. The covalent bond formation is then characterized by a new concept of the spindle structure. The spindle structure is a geometrical object of a region where principal electronic stress is positive along a line of principal axis of the electronic stress that connects a pair of the RDs of atoms and molecules. Using virial theorem of the rigged quantum electrodynamics (QED), a new energy density partitioning scheme is obtained using the kinetic energy densities. In the current paper, a concise judgment condition to identify the given unknown locality as a spindle structure of a covalent bond is formulated in the frame of the nonrelativistic limit of QED. A physical interpretation of the local dynamics of the chosen spindle structure is also guaranteed at the same time as the judgment of the generalized chemical reactivity in terms of the physical quantum mechanical law that is hierarchic and localized. A general frame to elucidate a feature structure and the character of the classification concerning the expression of the internal symmetry of chemical reaction to the chosen spindle structure class is given in a unified way. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
The detection of piroxicam, tenoxicam and their metabolites in equine urine by electrospray ionisation ion trap mass spectrometry
Authors: McKinney Andrew R. , Suann Craig J. , Stenhouse Allen M.
Published: September 2004

An investigation has been conducted into the metabolism and urinary excretion of orally administered piroxicam and tenoxicam in the horse. The major component detected in urine after the administration of piroxicam was 5′‐hydroxypiroxicam, which was detectable up to 24 h post‐administration. Unchanged piroxicam was present only as a minor component. In contrast, unchanged tenoxicam was the major component observed after the administration of tenoxicam, being detectable for 72 h post‐administration, while 5′‐hydroxytenoxicam was a minor component. Phase II β‐glucuronide conjugation in each case was found to be negligible. The ion trap mass spectral characteristics of piroxicam, tenoxicam, 5′‐hydroxypiroxicam and 5′‐hydroxytenoxicam under electrospray ionisation conditions were examined in some detail. Copyright © 2004 John Wiley & Sons, Ltd.
Development of a methodology for XPS curve‐fitting of the Si 2p core level of siloxane materials
Authors: O'Hare Lesley‐Ann , Parbhoo Bhukan , Leadley Stuart R.
Published: September 2004

A procedure for obtaining reliable binding energies in XPS for the various chemical states of silicon has been described in the literature for some organosilicon compounds. This manuscript describes further development of this work by the analysis of siloxane compounds that model complex polysiloxane systems. The use of accurate and restrained binding energies will allow greater confidence in the curve‐fitting of the Si 2p core level of industrially relevant coatings, which are typically featureless. The binding energy of a siloxy unit is known to increase when an oxygen atom replaces an alkyl group attached to the silicon atom. However, whereas previous work had estimated the binding energy shift between the M [(CH3)3SiO1/2], D [(CH3)2SiO2/2], T [(CH3)SiO3/2] and Q [SiO4/2] environments of silicon to be equal, or decreasing, this work has demonstrated a non‐linear increase in binding energy with increasing oxygen substitution. Copyright © 2004 John Wiley & Sons, Ltd.
Connecting men to academic and student affairs programs and services
Authors: Davis Tracy , Laker Jason A.
Published: September 2004

This chapter identifies significant barriers to developing effective programs and services for men and offers a framework for addressing this growing problem.
GM Football – Eingangspavillon des Headquarters von General Motors in Detroit
Authors: Dinort Ralf , Lemke Stefan
Published: September 2004

Der Artikel beschreibt Konstruktion, Herstellung und Montageplanung eines gläsernen Pavillons über einem elliptischen d. h. footballförmigen Grundriß von 30 m Länge und 10 m Breite. Die punktgehaltene Verglasung wird dabei in den 14 m hohen Fassaden von einem Seilnetz gestützt, welches in vertikaler Richtung vom Rand des räumlichen fischbauchförmigen Hauptträgers zum Boden spannt. In horizontaler Richtung verlaufen die Seile zwischen den seilumspannten Stützen des Hauptträgers. Von besonderer Bedeutung war bei der Planung dieses biaxial gekrümmten Seiltragwerkes die Detaillierung nicht nur im Hinblick auf sthetik, sondern insbesondere auf Montierbarkeit und Toleranzausgleich, sowie die Entwicklung eines schlüssigen Montagekonzeptes und der dazugehörigen Berechnungen.
Stabwerke auf Freiformflächen
Authors: Stephan Sören , Sánchez‐Alvarez Jaime , Knebel Klaus
Published: September 2004

Bei einigen bekannten Bauwerken der letzten Jahre, beispielsweise bei der DG‐Bank in Berlin (Architekt: Frank Gehry), dem Arts Center in Singapur (Architekt: Vikas Gore), dem Britischen Museum in London (Architekt: Norman Foster) oder kürzlich den Glasdächern über der Zentralachse und dem Servicezentrum der Neuen Messe in Mailand (Architekt: Massimiliano Fuksas), sind Freiformflächen zunehmend für Gebäudehüllen eingesetzt worden. Der folgende Aufsatz befaßt sich mit den geometrischen Aspekten und den mit der praktischen Umsetzung dieser Bauarten verbundenen Problemen. Es werden insbesondere eine Vielzahl verschiedener Knotenkonstruktionen vorgestellt, ohne die Stabstrukturen für Freiformflächen nicht realisierbar wären.