bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prenatal diagnosis of two rare de novo structural aberrations of the Y chromosome: cytogenetic and molecular analysis
Authors: Velissariou Voula , Antoniadi Thalia , Patsalis Philippos , Christopoulou Stavroula , Hatzipouliou Athina , Donoghue Jackie , Bakou Katerina , Kaminopetros Petros , Athanassiou Vassilis , Petersen Michael B. 
Published: September 2002

AbstractTwo rare de novo structural aberrations of the Y chromosome were detected during routine prenatal diagnosis: a satellited non‐fluorescent Y chromosome (Yqs), the first de novo Yqs to be reported in a fetus, and a terminal deletion of the Y chromosome long arm del(Y)(q11). In both cases detailed cytogenetic and molecular analyses were undertaken. In the case of the Yqs it was demonstrated by fluorescence in situ hybridization (FISH) that the satellites were derived from chromosome 15. In the case of the del(Yq), it was shown with molecular analysis by polymerase chain reaction (PCR) amplification of sequence‐tagged sites (STS‐PCR) that the deleted portion of the long arm of chromosome Y included the azoospermia factor loci, AZFb and AZFc. The clinical significance of these findings is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and properties of polydimethylsiloxane‐containing block copolymers via living radical polymerization
Authors: Huan Kim , Bes Laurence , Haddleton David M. , Khoshdel Ezat 
Published: September 2002

AbstractPolydimethylsiloxane (PDMS) block copolymers were synthesized by using PDMS macroinitiators with copper‐mediated living radical polymerization. Diamino PDMS led to initiators that gave ABA block copolymers, but there was low initiator efficiency and molecular weights are somewhat uncontrolled. The use of mono‐ and difunctional carbinol–hydroxyl functional initiators led to AB and ABA block copolymers with narrow polydispersity indices (PDIs) and controlled number‐average molecular weights (Mn's). Polymerization with methyl methacrylate (MMA) and 2‐dimethylaminoethyl methacrylate (DMAEMA) was discovered with a range of molecular weights produced. Polymerizations proceeded with excellent first‐order kinetics indicative of living polymerization. ABA block copolymers with MMA were prepared with between 28 and 84 wt % poly(methyl methacrylate) with Mn's between 7.6 and 35 K (PDI <1.30), which show thermal transitions characteristic of block copolymers. ABA block copolymers with DMAEMA led to amphiphilic block copolymers with Mn's between 9.5 and 45.7 K (PDIs of 1.25–1.70), which formed aggregates in solution with a critical micelle concentration of 0.1 g dm−3 as determined by pyrene fluorimetry experiments. Monocarbinol functional PDMS gave AB block copolymers with both MMA and DMAEMA. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1833–1842, 2001
Syntheses of amphiphilic block copolymers by living cationic polymerization of vinyl ethers and their selective solvent‐induced physical gelation
Authors: Sugihara Shinji , Matsuzono Shin‐Ichiro , Sakai Hideki , Abe Masahiko , Aoshima Sadahito 
Published: September 2002

AbstractAmphiphilic diblock copolymers were prepared by the living cationic polymerization of vinyl ethers in the presence of added bases, and their selective solvent‐induced physical gelation behavior was investigated. The block copolymerization of 2‐phenoxyethyl vinyl ether (PhOVE) and 2‐methoxyethyl vinyl ether (MOVE) was carried out in the presence of ethyl acetate with Et1.5AlCl1.5 in toluene at 0 °C. Despite the rate difference, diblock copolymers with a very narrow molecular weight distribution were obtained, quantitatively. By adding the selective solvent, water, to the acetone solution of the diblock copolymer, PhOVE200‐b‐MOVE400, physical gelation occurred suddenly and the system ceased to flow, maintaining transparency. Viscoelastic measurements and transmission electron microscopic observations were performed to examine the characteristic gelation behavior and structure of the obtained gels. Various gelation conditions and physical gelation by other amphiphilic block copolymers were also designed on the basis of the solubility of each block segment. Further, new forms of physical gelation, accompanied by the solubilization of immiscible organic compounds, were achieved using similar diblock copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3190–3197, 2001
Online monitoring of birefringence development in heat‐setting polymer films with a fast dual‐wavelength optical technique. I. Uniaxially oriented poly(ethylene naphthalate)
Authors: Galay J. , Cakmak M. 
Published: September 2002

AbstractThe purpose of this article is to study the fast structural changes that take place during the deformation and heat setting of uniaxially preoriented poly(ethylene 2,6‐naphthalate) films. For this purpose, an online birefringence measurement system coupled with a heat‐setting oven was used. In the online birefringence system, whose details were reported previously (H. Venkatesvaran and M. Cakmak, SPE ANTEC Tech Pap 1993, 39, 257; H. Venkatesvaran and M. Cakmak, Polym Eng Sci 2001, 41, 341), a green and red laser is passed through the films being annealed in a heat‐setting chamber; the resulting data are analyzed for the details of structural mechanisms that take place during this process. This technique is shown to be capable of detecting reversals in birefringence development; as a result, complex sequences of structural evolution can be tracked. The design of this system allows one to observe not only the increase or decrease in birefringence during the course of the heat‐setting process but also the rate dependencies on processing variables. In this study, we establish that the rate of structural rearrangement, as detected by birefringence, depends strongly on the state of the pre‐existing chain orientation and the level of crystallinity. Increased levels of preorientation in the films results in decreases in the rate of birefringence change during heat setting. This is primarily attributed to the increased levels of steric hindrance developed with the increase in orientation and crystallinity in the preoriented samples. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1107–1121, 2001
Steel plated structures
Authors: Johansson Bernt , Veljkovic Milan 
Published: September 2002

AbstractSteel plated structures are important because they are used in large structures of vital importance for society. For the steel construction industry they are however of less importance as they are a small part of the turnover. Since the big disasters with box girder bridges more than thirty years ago very little money, public or private, has been spent on development of plated structures and hence progress has been fairly slow. Fortunately, the scientific interest in buckling problems is still high and this has led to some important steps forward. The European project of harmonizing design standards has brought plated structures onto the agenda again in connection with the conversion of Eurocode 3 to EN. There are several open questions, some of which are discussed in the context of new experimental and theoretical results.
Seismic monitoring and early damage assessment systems in Japan
Authors: Yamazaki Fumio 
Published: September 2002

AbstractRecent developments of seismic monitoring systems and early damage assessment systems in Japan are reviewed. National and local governments in Japan have deployed numerous seismic instruments for the purpose of disaster management, mostly after the 1995 Kobe earthquake. Utility companies and highway authorities have also established seismic networks in order to use earthquake information for supply or traffic control just after the occurrence of an earthquake. Based on the collected seismic information and the GIS‐based inventory data, held on computer, early damage assessments are conducted and the results are used for emergency management at the stage when actual damage information is scarce. In this paper, typical seismic networks and early damage assessment systems recently developed in Japan are presented and their roles in disaster management and future directions are discussed.
Migration of protons in a chain of tyrosine residues
Authors: Stefanov V. E. , Tulub A. A. 
Published: September 2002

AbstractThis article deals with the proton migration in a tyrosine stack, which models the proton channels existing in a number of proteins, including tubulin. The magnesium ion Mg2+ within the complex with guanosine triphosphate facilitates dissociation of a water molecule through initiating a shift of protons along the chain composed of relatively distant tyrosine residues. The process is thermodynamically stable (ΔG298<0). The energy barrier for the protein shift does not exceed 3.15 kJ/mole. A relatively weak electrostatic field mimicking electret properties of proteins facilitates long‐distance proton migration. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 409–415, 2001
Multiresolution analysis of density operators, electron density, and energy functionals
Authors: Nagy Szilvia , Pipek János 
Published: September 2002

AbstractNumerical calculations show that, in extended electronic systems, complex one‐particle states appear with different shape characteristics at different length scales. New results in the theory of wavelets are applied in this contribution for a consistent description of densities and density operators with a continuous kernel at various length scales. It is proved here that, for real physical systems, according to physical intuition, neither arbitrarily fine nor arbitrarily rough details of the wave function and density operators can exist. It is also shown that the calculation of both kinetic energy and interaction energy expectation values can be reduced to the determination of some universal functions defined on integer‐valued arguments. © 2001 John Wiley & Sons, Inc. Int J Quant Chem, 2001
Conformational study of a new SGTx1 neurotoxin from the spider Scodra griseipes using mass spectrometry
Authors: Marvin Laure , Lange Catherine 
Published: September 2002

AbstractSGTx1 is a new neurotoxin from the venom of Scodra griseipes. Because of the small quantity of this natural peptide available, mass spectrometry was used to obtain information on its higher‐order structure. The kinetics of reduction by 1,4‐dithiothreitol (DTT) was monitored by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS), and showed that one of the three disulfide bridges was appreciably more accessible to the DTT. Studies based on the charge state distribution (CSD) and H/D exchange of the non‐reduced peptide, under neutral and acidic conditions, were performed using electrospray mass spectrometry (ES‐MS). In neutral solution, SGTx1 showed a maximum charge state of four compared with seven potentially protonated basic residues, and all labile hydrogens were exchanged. However, under acidic conditions, a maximum charge state of only five was observed, and four of the labile hydrogens could not be deuterated. These observations are interpreted in terms of a rigid structure maintained by the disulfide bridges, which can be temporarily relaxed by disulfide bridge scrambling only at higher pH values. Copyright © 2001 John Wiley & Sons, Ltd.
On‐line measurement of the absolute humidity of air, breath and liquid headspace samples by selected ion flow tube mass spectrometry
Authors: S̆panĕl Patrik , Smith David 
Published: September 2002

AbstractWe describe how selected ion flow tube mass spectrometry (SIFT‐MS) can be used to determine the absolute humidity of air, breath and liquid headspace samples. This involves the determination of the relative count rates of the H3O+ ions and those H3O+.(H2O)1,2,3 hydrate ions that inevitably form in the helium carrier gas when humid samples are being analysed by SIFT‐MS using H3O+ precursor ions. This requires an understanding of the kinetics of hydrated hydronium ion formation, the involvement of mass discrimination in the analytical quadrupole mass spectrometer and the decreased diffusive loss of the heavier hydrates along the flow tube. Thus, we show that the humidity of breath and liquid headspace samples, typically at the few percent level, can be directly obtained on‐line to the SIFT‐MS instrument along with the concentrations of trace gases, which are present at much lower levels. We emphasise the value of parallel humidity measurements in ensuring good real‐time sampling of breath and liquid headspace and the value of such measurements to trace gas analysis using SIFT‐MS. Copyright © 2001 John Wiley & Sons, Ltd.
Reactivity of anomeric 1α‐ and 1β‐pentofuranosyl azide derivatives in ammonia chemical ionization
Authors: Kralj Bogdan , Kocjan Darko , Kobe Jože 
Published: September 2002

AbstractElectron impact (EI), fast atom bombardment (FAB) and ammonia chemical ionization [CI(NH3)] mass spectrometry were applied with the aim of differentiating between the anomeric 1α‐ and 1β‐azidopentofuranosyl derivatives. Calculated ammonium affinities [AA(M)] and proton affinities [PA(M)] show that β‐anomers have higher affinities for H+ and NH4+ ions than α‐azides. Protonated molecules, obtained by CI(NH3) of azidofuranosyl derivatives, lose HN3 giving abundant furanosyl (S+) ions. Ammonia solvation of MH+ ions competes with the previous reaction producing the [SNHN2NH3]+ ion, a competitive product to the ammonium‐attached [SN3NH4]+ ion. The fragmentation pathways of the stable and metastable [MNH4]+, MH+ ions, and several other important fragment ions, were determined using mass analyzed ion kinetic energy spectrometry (MIKES). The abundance of the [SN3NH4]+ and/or [SNHN2NH3]+ ions was found to correlate inversely with the exothermicity of ammonia solvation of the MH+ ion. The abundance of the fragment ions [SNHNH3]+, [SNH3]+ and SNH+ in some examples correlates with the exothermicity of the corresponding [MNH4]+ and MH+ parent ion formation. The fragment ions SNH3+ and SNHNH3+ can be formed, at least in part, in the ammonia solvation reaction of the S+ and SNH+ ions taking place within the high‐pressure region of the CI ion source. Copyright © 2001 John Wiley & Sons, Ltd.
Practical and theoretical considerations in the gas chromatography/combustion/isotope ratio mass spectrometry δ13C analysis of small polyfunctional compounds
Authors: Docherty Gordon , Jones Vicky , Evershed Richard P. 
Published: September 2002

AbstractCarbohydrates and proteins are among the most abundant naturally occurring biomolecules and so suitable methods for their reliable stable isotope analysis by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) are required. Due to the non‐volatile nature of these compounds they require hydrolytic cleavage to their lower molecular weight subunits and derivatisation prior to GC/C/IRMS analysis. The addition of carbon to the molecules and any kinetic isotopic fractionation associated with derivatisation must be accounted for in order to provide meaningful stable isotope values and estimates of propagated errors. To illustrate these points amino acid trifluoroacetate/isopropyl esters and alditol acetates were prepared from authentic amino acids and monosaccharides, respectively. As predicted from the derivatisation reaction mechanisms, a kinetic isotope effect was observed which precludes direct calculation of δ13C values of the amino acids and monosaccharides by simple mass balance equations. This study shows that the kinetic isotope effect associated with derivatisation is both reproducible and robust, thereby allowing the use of correction factors. We show how correction factors can be determined and accurately account for the addition of derivative carbon. As a consequence of the addition of a molar excess of carbon and the existence of a kinetic isotope effect during derivatisation, errors associated with determined δ13C values must be assessed. We illustrate how such errors can be quantified (for monosaccharides ±1.3‰ and for amino acids between ±0.8‰ and ±1.4‰). With the magnitude of the errors for a given δ13C value of a monosaccharide or amino acid quantified, it is possible to make reliable interpretations of δ13C values, thereby validating the determination of δ13C values of amino acids as TFA/IP esters and monosaccharides as alditol acetates. Copyright © 2001 John Wiley & Sons, Ltd.
Quantitative determination of noncovalently bound acridinium in protein conjugates by liquid chromatography/electrospray ion trap mass spectrometry
Authors: Adamczyk Maciej , Gebler John C. , Shreder Kevin , Wu Jiang 
Published: September 2002

AbstractA sensitive and robust liquid chromatography/electrospray ion trap mass spectrometry (LC/MS/MS) method has been developed for the quantitative determination of noncovalently bound acridinium free acid in protein‐acridinium conjugates. The lower level of quantitation (LOQ) for acridinium free acid was determined to be 0.6 ng. The assay was validated with a linear concentration range of 0.6–60 ng. The method requires minimum sample handling and is specific, reproducible, and provides a new aspect for protein‐acridinium conjugate characterization. Copyright © 2001 John Wiley & Sons, Ltd.
Hydrogen isotope analysis of natural abundance and deuterium‐enriched waters by reduction over chromium on‐line to a dynamic dual inlet isotope‐ratio mass spectrometer
Authors: Donnelly Terry , Waldron Susan , Tait Andrew , Dougans Julie , Bearhop Stuart 
Published: September 2002

AbstractThis paper describes the application of a simple chromium reduction furnace which can be interfaced with a dual inlet isotope‐ratio mass spectrometer thus providing the capacity for cheap, fast, accurate and precise measurement of δDV−SMOW by dynamic mass spectrometry. Measurements are precise to the order of ≤0.5‰. Mean 95% confidence intervals for the Vienna Standard Mean Ocean Water (V‐SMOW) to Standard Light Antarctic Precipitation (SLAP) range are in the order of 2.5‰ and the system is linear over the range −428 to 23,000‰. Memory effects do exist, but are small for natural abundance samples and can be minimised by careful planning of the analytical load. Copyright © 2001 John Wiley & Sons, Ltd.
Study on application of CMA to land mobile LEO satellite communication systems based on a deterministic channel model
Authors: Xu Chang Qing , Law Choi Look , Yoshida Susumu 
Published: September 2002

AbstractThis paper studies the application of the constant modulus algorithm (CMA) in land mobile low earth orbit (LEO) satellite communication systems. Two propagation phenomena prevail in narrow band land mobile LEO satellite channel, namely, adjacent channel interference (ACI) and frequency‐non‐selective fading. The performance of CMA for ACI cancellation and the behaviours of CMA in frequency‐non‐selective fading channels are evaluated using a digital beamforming (DBF) array antenna simulation scheme. All these evaluations are based on a simple but efficient channel model which provides a good and fast simulation method for land mobile LEO satellite channels. The restricted Jakes Doppler power spectral density (psd) function is incorporated into the model to ensure that it will be appropriate for the evaluation of a DBF antenna. Our results reveal that CMA can reject ACI and work well in frequency‐non‐selective fading channels. Copyright © 2002 John Wiley & Sons, Ltd.
Oscillatory adsorption: a first‐principles linear kinetic model
Authors: Quinton J. S. , Dastoor P. C. 
Published: September 2002

AbstractThe kinetics of propyltrimethoxysilane (PTMS) films exhibit oscillatory adsorption when grown upon aluminium and iron oxide surfaces. This phenomenon is identified by the presence of non‐linear oscillations in adsorbate surface coverage, measured by X‐ray photoelectron spectroscopy (XPS), as a function of exposure time and solution concentration. In this paper, a mathematical model based upon the chemistry of the adsorption system is presented to describe the time‐dependent behaviour. The oscillatory nature of organosilane adsorption can be modelled by the evolution of three unique adsorbate species whose presence at the surface is dominated by displacement processes. The model presented here quantitatively describes the rate, non‐linearity and influence of experimental deposition parameters on PTMS adsorption. From the mathematical construct, a model of the physical origins of the oscillatory adsorption phenomenon is presented. Copyright © 2001 John Wiley & Sons, Ltd.
Surface and structure analysis of ultrathin multilayer structures for copper diffusion studies
Authors: Sun Y.‐M. , Lee S. Y. , Lemonds A. , Lozano J. , Zhou J.‐P. , Ekerdt J. G. , White J. M. , Imesh I. 
Published: September 2002

AbstractThe development of ultrathin multilayer structures suitable for copper diffusion studies was investigated. The structures were examined by x‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS). Copper/barrier/SiO2/Si(100) and barrier/Cu/SiO2/Si(100) structures were fabricated on thermally grown SiO2 by physical vapor deposition. Both tantalum and tungsten were chosen as the copper diffusion barrier and their thickness was held at <10 nm. For 2 nm of Cu on 10 nm of Ta, XPS showed steadily increasing Ta 4f and decreasing Cu 2p signals with annealing time at 400 °C, with changes occurring rapidly over the first 60 min and then much slower for the remaining time (up to 8 h). Cross‐sectional TEM indicated copper island formation on the tantalum surface. Copper islands were also found on tungsten films. For the reverse structure, W(5 nm)/Cu(700 nm)/SiO2/Si(100), no island formation was found after the thermal treatment. X‐ray photoelectron spectroscopy did detect a very weak Cu 2p signal after annealing for 8 h at 400 °C, which is equivalent to ∼0.2% copper bulk concentration in the tungsten barrier. Copyright © 2001 John Wiley & Sons, Ltd.
Distribution of the composition and micromechanical properties of Be/316L stainless steel following diffusion bonding
Authors: Zhang Peng‐cheng , Bai Bin , Shen Liang , Zhou Jue‐sheng 
Published: September 2002

AbstractJoining of beryllium and 316L stainless steel by hot isostatic pressing (HIP) with and without an interlayer was investigated. Metallurgical observation, scanning Auger microscopy (SAM) and nanoindentation were performed for basic characterization of bonded joints. It is shown that the diffusion depth of Be into 316L stainless steel is much greater than that of Cr, Ni or Fe into beryllium, and it is ∼400 µm. The nanohardness of the diffusion zone on the beryllium side increases sharply due to intermetallic compounds, and the tensile strength of the Be/316L joint is <10 MPa. For a Be/Cu/316L joint, a Cu interlayer blocks the diffusion of Fe into Be, but Ni is gathered at the Cu/316L interface and a crack is formed at this stress field. For a Be/Cu/Ni/316L joint, the diffusion depth increases further. Change of composition, mechanical property with distance in diffusion zone is smooth, and the tensile strength increases to ∼50 MPa. Copyright © 2001 John Wiley & Sons, Ltd.