bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrenes as intermediates in the thermal decomposition of aliphatic azides
Authors: Arenas J. F. , Marcos J. I. , Otero J. C. , Tocón I. L. , Soto J. 
Published: August 2002

AbstractN2 extrusion from hydrazoic acid, methyl azide, and ethyl azide to yield the corresponding nitrene has been studied with high‐level ab initio calculations. Geometry optimizations of stationary points and surfaces crossing seams were carried out with the complete active space self‐consistent field (CASSCF) method, and their energies were reevaluated with the second‐order multireference perturbation (CASPT2) theory and corrected by the zero‐point energy (ZPE). The analytic harmonic frequencies calculated at the CASSCF level have been used in the ZPE corrections. The decomposition reaction is a competitive mechanism between a spin‐allowed and a spin‐forbidden channel, giving the nitrene either in the singlet or triplet states. The energy barrier height for XNN2 bond fission is approximately the same in both channels for each azide, respectively. The spin‐orbit (HSO) interactions were determined at the minimum energy point on the seam of crossing between the singlet and triplet surfaces, the value ranges from 43.9 cm−1 in hydrazoic acid to 43.3 cm−1 in ethyl azide. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 241–248, 2001
On prolate spheroidal wave functions for signal processing
Authors: Larsson B. , Levitina T. , Brändas E. J. 
Published: August 2002

AbstractA spectral window, ideal from the energy concentration viewpoint, is known to be a prolate spheroidal wave functionS0l(c,η). These functions exhibit unique properties that are of special importance in signal processing. However, in the literature they are often being reported as functions too difficult to handle numerically and they are therefore in practice used much less than they should be. On the other hand, powerful and efficient numerical techniques have been devised to compute the full set of prolate spheroidal wave functions and they have successfully been applied to various scattering problems in acoustics and electrodynamics. These techniques should be useful to problems in signal processing both in multiple applications of conventional spheroidal functions and, appropriately modified, to compute so‐called generalized spheroidal wave functions, in treating signals depending on several variables. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Two‐dimensional gel electrophoresis/matrix‐assisted laser desorption/ionisation mass spectrometry of commercial bovine milk
Authors: Galvani Marina , Hamdan Mahmoud , Righetti Pier Giorgio 
Published: August 2002

AbstractProteins in commercial bovine milk have been separated by two‐dimensional gel electrophoresis and examined by matrix‐assisted laser desorption/ionisation mass spectrometry. Gel separation was conducted in two different pH gradients, 3–10 and 6–11; the latter range resulted in a higher spot resolution and favoured the basic proteins. We have limited the time‐of‐flight mass spectrometry analysis to the linear mode to examine the capability of reliable relative molecular masses of the intact proteins in their characterisation. The present study draws attention to the difficulty of identifying basic proteins with low molecular masses (below 12000 Da) that are commonly encountered in milk samples. Copyright © 2001 John Wiley & Sons, Ltd.
High surface area membrane introduction mass spectrometry for analysis of volatile and semi‐volatile organic compounds in air
Authors: Riter Leah S. , Takáts Zoltán , Charles Laurence , Cooks R. Graham 
Published: August 2002

AbstractThe construction, optimization, and testing of a novel geometry for a semi‐permeable polydimethylsiloxane membrane introduction mass spectrometry (MIMS) system is described. A long poly(dimethylsiloxane) capillary membrane (0.30 mm i.d., 0.64 mm o.d., 60 cm long) was positioned coaxially inside polytetrafluoroethylene tubing (0.80 mm i.d. and 1.60 mm o.d.), allowing for a large surface area membrane of relatively small thickness. Helium, flowing counter‐current on the vacuum side of the membrane, swept the permeate into the mass spectrometer. This optimized geometry for permeation MIMS air analysis allows on‐line detection of volatile and semi‐volatile organic compounds of environmental interest, with limits of detection in the ppt range and a linear response over 3 to 4 orders of magnitude. The system is characterized by short rise and fall times, 10 and 48 s, respectively, for toluene. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization of tetrathiofulvalene compounds using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Xiong Shaoxiang , Pu Dan , Xin Bin , Wang Guanghui 
Published: August 2002

AbstractTetrathiofulvalene compounds are important components of charge‐transfer complexes, which may be applied in various fields of scientific research and practical applications. Some of these compounds cannot be characterized by mass spectrometry. Here, matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry was used for the characterization of tetrathiofulvalenes. The samples could be easily desorbed and ionized to form singly charged ions, and mass spectra with isotopic resolution readily obtained. The mass spectrometric results for 26 compounds have shown that MALDI‐TOF is more effective and convenient than other mass spectrometry methods, and resolves the problem of mass spectrometric characterization of tetrathiofulvalene compounds. Copyright © 2001 John Wiley & Sons, Ltd.
Negative‐ion electrospray ionization tandem mass spectrometry of N‐phosphoryl amino acids and dipeptides
Authors: Chen Zhong‐Zhou , Chen Shui‐Bing , Chen Yi , Li Yan‐Mei , Chen Jing , Zhao Yu‐Fen 
Published: August 2002

AbstractThe negative‐ions of N‐phosphoryl amino acids were studied by electrospray ionization tandem mass spectrometry (ESI‐MS/MS). The negative‐ion ESI‐MS/MS of N‐phosphoryl amino acids showed characteristic fragmentation patterns different from those observed in the corresponding positive‐ion ESI‐MS/MS and negative‐ion fast‐atom bombardment mass spectra. For negative‐ion ESI‐MS/MS, a unique fragmentation from the N‐terminal of N‐phosphoryl amino acids or peptides containing a free β‐OH or CO2H group was observed to yield the characteristic fragment ion (RO)2P(O)O−. The ease of the rearrangement depended on the position of the hydroxyl group in amino acids or peptides, and the N → O rearrangement mechanism was proposed to involve the participation of the hydroxyl group. From previous solution‐phase experiments and theoretical calculations, it was found that the β‐OH group was more active than γ‐OH, and the corresponding difference in negative‐ion ESI‐MS/MS was consistent with those previous findings. Copyright © 2002 John Wiley & Sons, Ltd.
Ion trap mass spectrometry in the structural analysis of haemoglobin peptides modified by epichlorohydrin and diepoxybutane
Authors: Miraglia Nadia , Basile Adriana , Pieri Maria , Acampora Antonio , Malorni Livia , Giulio Beatrice De , Sannolo Nicola 
Published: August 2002

AbstractIon trap mass spectrometry has been shown to be particularly suitable for the structural analysis of high molecular weight peptides directly fragmented in the mass analyser without needing further sub‐digestion reactions. Here we report the advantages of using multi‐stage ion trap mass spectrometry in the structural characterisation of haemoglobin alkylated with epichlorohydrin and diepoxybutane. Alkylated globins were digested with trypsin and the peptide mixtures were analysed by MS3. This technique allows the sequential fragmentation of peptides under analysis, giving rise to MS3 product ion spectra with additional information with respect to MS2 mass spectra. The results obtained complete the previously reported structural characterisation of alkylated haemoglobin, demonstrating the potential of ion trap mass spectrometry. Copyright © 2002 John Wiley & Sons, Ltd.
Structural characterization of steroidal saponins by electrospray ionization and fast‐atom bombardment tandem mass spectrometry
Authors: Liang Feng , Li Li‐jun , Abliz Zeper , Yang Yun‐chong , Shi Jian‐gong 
Published: August 2002

AbstractThe structural characterization of four steroidal saponin compounds involving two and three sugar groups, namely spirostanol saponins and furostanol saponins, were investigated by positive ion fast‐atom bombardment (FAB), electrospray ionization mass spectrometry (ESI‐MS) and tandem mass spectrometry (MS/MS) techniques. Important structural information was obtained from collision‐induced dissociation (CID) and FAB‐MS spectra with different liquid matrices. It was found that a characteristic fragmentation involving the loss of 144 Da arising from the cleavage of the E‐ring was observed when there was no sugar chain at the C‐26 position. When a glucoside group was substituted at the C‐26 position, this C‐26 sugar moiety was preferentially eliminated. All of these compounds produced a major product ion with a stable skeleton structure at m/z 255. The results of this paper can assist structural analysis of mixtures of steroidal saponins. Copyright © 2002 John Wiley & Sons, Ltd.
High gain observer based on a triangular structure
Authors: Hammouri Hassan , Targui Boubekeur , Armanet Frederic 
Published: August 2002

AbstractA high gain observer based on a triangular structure of nonlinear systems is proposed. An algorithm capable of calculating a gain of the observer is given. This observer synthesis is then extended to a class of multi‐output nonlinear systems which contains the model of binary distillation columns. Finally, we illustrate the performance of the estimator using numerical simulations of a methanol–ethanol distillation column. Copyright © 2002 John Wiley & Sons, Ltd.
Links between the parameter space and frequency domain methods of robust control
Authors: Güvenç Levent , Ackermann Jürgen 
Published: August 2002

AbstractTwo main approaches to robust control are the parametric and frequency domain approaches. The aim of this paper which starts with tutorial sections on both approaches is to compare and establish links between the parameter space method of the parametric approach and frequency domain methods, with special emphasis on the structured singular value (SSV) method. In an effort to combine the useful properties of both approaches, two SSV minimization based design techniques in controller parameter space are presented here. A simple interpretation of real SSV in plant parameter space and its further implications for analysis and design are also presented. Copyright © 2001 John Wiley & Sons, Ltd.
Random maps, coalescing saddles, singularity analysis, and Airy phenomena
Authors: Banderier Cyril , Flajolet Philippe , Schaeffer Gilles , Soria Michèle 
Published: August 2002

AbstractA considerable number of asymptotic distributions arising in random combinatorics and analysis of algorithms are of the exponential‐quadratic type, that is, Gaussian. We exhibit a class of “universal” phenomena that are of the exponential‐cubic type, corresponding to distributions that involve the Airy function. In this article, such Airy phenomena are related to the coalescence of saddle points and the confluence of singularities of generating functions. For about a dozen types of random planar maps, a common Airy distribution (equivalently, a stable law of exponent \documentclass{article}\pagestyle{empty}\begin{document}$\frac{3}{2}$\end{document}) describes the sizes of cores and of largest (multi)connected components. Consequences include the analysis and fine optimization of random generation algorithms for a multiple connected planar graphs. Based on an extension of the singularity analysis framework suggested by the Airy case, the article also presents a general classification of compositional schemas in analytic combinatorics. © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 19: 194–246, 2001
Scientific literacy for citizenship: Tools for dealing with the science dimension of controversial socioscientific issues
Authors: Kolstø Stein D. 
Published: August 2002

AbstractThis article offers a general framework for examining the science dimension of controversial socioscientific issues. Eight specific content‐transcending topics to be emphasized in science education are proposed. The topics are grouped under the headings science as a social process, limitations of science, values in science, and critical attitude. Each topic is explored, and it is argued that knowledge of the topics can serve as tools for students' examination of science‐related claims in controversial socioscientific issues. The underlying perspective here is empowerment and the needs of students as lay people. The need of society as a whole for decisions to be made on a broad and firm basis is nevertheless also included. The main reason for suggesting the eight content‐transcending topics is to provide focal points for the future development of teaching models aimed at science education for citizenship. © 2001 John Wiley & Sons, Inc. Sci Ed 85:291–310, 2001.
Biomesogenic (pre)ordering phenomena and matrix reactions of nucleosides on polyuridylic acid templates studied by scanning force microscopy
Authors: Meister Walter‐Veselý , Hauser Anton L. , Lindau Sabine , Birch‐Hirschfeld Eckhard , Reinhardt Jürgen , Friese Klaus , Bohley Christian , Gromann Ulrich , Hoffmann Siegfried 
Published: August 2002

AbstractBifunctionally reactive nucleoside and distant nucleoside analogues— adenosine (Ado), S‐[(adenine‐9‐yl)methoxyethyl]‐L‐cysteine sodium salt (cysA) and 9‐vinyladenine (vA)— assemble on complementary polyuridylic acid templates to form complex lyomesophases. Mesophase‐derived scanning force microscopy (SFM) elucidations reveal geometries ranging from rod‐ and toroid‐like (cysA) to prevailing toroid‐like spheric arrangements (Ado, vA). The dynamics of (U)n·n(vA) self‐organizations in hybridization, de‐ and renaturation are followed up by SFM. The biomesogenic preordering behaviour suggests decisive roles in matrix‐directed polycondensations and polymerizations of nucleic acid monomer constituents on assembling polynucleotide templates. Orientating γ‐polymerizations yield (U)n matrix‐informed 2(U)n·(vA)n arrangements that link the formerly almost discrete toroids into more chromosomal‐like patterns. The SFM investigations are assisted by polarizing microscopy and molecular modelling. Copyright © 2002 John Wiley & Sons, Ltd.
Surface cleaning and characterization of yttria‐stabilized zirconia
Authors: de Ridder M. , van Welzenis R. G. , Brongersma H. H. 
Published: August 2002

AbstractCleaning substrate surfaces and checking the effectiveness of the cleaning method are two very important aspects of reliable surface analysis. The absence of a cleaning process leading to an yttria‐stabilized zirconia (YSZ) surface that is free of contaminants and of unchanged structure has inspired us to investigate a new surface cleaning method based on a combination of high vacuum annealing at 300°C and oxidation with atomic oxygen. The efficiency of the cleaning procedure is examined by studying the surface composition after each stage of the process with low‐energy ion scattering (LEIS or ISS) and x‐ray photoelectron spectroscopy (XPS). The cleaning method results in complete removal of contaminants adsorbed from the ambient atmosphere, such as water and hydrocarbons. No segregation or sputtering effects due to the cleaning procedure are observed. The process also is compared with more conventional methods such as thermal oxidation and plasma etching. Although this study focuses on cleaning polycrystalline YSZ, which is inherently difficult to clean, other oxides and several metals also are investigated. For all the oxides studied, the newly proposed cleaning strategy removes up to ∼90% more contamination than the commonly used method of thermal oxidation. In the case of metals, the surface carbon is replaced by oxygen, which can be removed much easier. Additional segregation of bulk carbon is avoided. Copyright © 2002 John Wiley & Sons, Ltd.
Influences of intergranular precipitates on the structure and chemistry of interface in silicon nitride materials
Authors: Xu Fang‐Fang , Wang Chang‐Meng , Bando Yoshio , Mitomo Mamoru 
Published: August 2002

AbstractPure β‐Si3N4 is used in the present work as the starting powder to synthesize α‐sialon (α′) ceramics; 5 wt.% α′‐seeds are added to promote nucleation of α‐sialon. Transmission electron microscopy (TEM) observations reveal an inhomogeneous microstructure in which intergranular precipitates are produced in some regions where the structure and the chemistry of the interfaces vary significantly. The surfaces of the sialon grains adjacent to the precipitates are always rounded and corrugated, and the interfacial thickness increases. An internal band structure is usually discovered in these grains. Chemical analyses find that a small number of Y ions have been incorporated into the surface lattice. A possible formation mechanism of the corrugated surface is proposed and suggests a redissolution process of sialon grains during the crystallization of intergranular precipitates and an enhanced growth during cooling that is governed by interface‐controlled kinetics. The increased number of growth sites eventually gives rise to a corrugated surface. Copyright © 2001 John Wiley & Sons, Ltd.
A measure of continuity of care based on the multiplicative intensity model
Authors: Hussein A. , Carrière K. C. 
Published: August 2002

AbstractContinuity of care is a concept that is frequently used to measure patient satisfaction and other benefits provided by the health care system. Although several measures of continuity of care are used, most are built on unrealistic assumptions about random visits to providers and do not utilize all available information. In this paper we advocate stochastic processes to model continuity of care, and we propose a new measure of provider continuity based on the multiplicative intensity model. Using data on hypertensive patients in the province of Alberta, Canada, we demonstrate the utility of our method that incorporates ways to accommodate covariate information. Compared to the currently popular method, the proposed method in this paper is shown to assess both concentration of care aspects and other visit‐based characteristics of the care being provided. Copyright © 2002 John Wiley & Sons, Ltd.
A GEE approach to estimating sensitivity and specificity and coverage properties of the confidence intervals
Authors: Sternberg Maya R. , Hadgu Alula 
Published: August 2002

AbstractA generalized estimating equation (GEE) approach is used to estimate the sensitivity and specificity of five non‐culture screening tests for detecting Chlamydia trachomatis in endocervical specimens from women attending family planning clinics. Since the estimates of these parameters can be very close to the upper limit of one, confidence interval construction based on the traditional approaches, such as the delta method or a back‐transformation approach, may not have the stated coverage. We compare different approaches to calculating confidence intervals for the sensitivity and specificity from the results of the GEE approach. These methods include the delta method, a back‐transformation approach, and a bootstrap approach. In addition, we use simulations to investigate the estimated coverage rates of the delta method and the back‐transformation approach. Published in 2001 by John Wiley & Sons, Ltd.
Using structural equation models to evaluate the magnitude of measurement error in blood pressure
Authors: Batista‐Foguet J. M. , Coenders G. , Artés Ferragud M. 
Published: August 2002

AbstractThis article aims to compare alternative methods for estimating the quality of blood pressure measurements. Traditional within‐subject variance estimates in mixed analysis of variance models are compared to multiple‐group multitrait‐multimethod models, which are a particular case of mean‐and‐covariance‐structure confirmatory factor analysis models. Confirmatory factor analysis models belong to the family of structural equation models and were specifically developed to analyse psychosociological traits measured by tests or surveys, but they have also proved suitable for evaluating the quality of blood pressure measurements. Confirmatory factor analysis models are less restrictive and provide more detailed information than traditional approaches, enable researchers to compute weighted averages of individual measures with optimal measurement quality, make it easier to correct the biasing effects of measurement error on the results of substantive studies, and make the use of equivalent replicated measures unnecessary under certain conditions. Copyright © 2001 John Wiley & Sons, Ltd.
Narrative inquiry: designing the processes, pathways and patterns of changea
Authors: Gill Peggy B. 
Published: August 2002

AbstractNarrative inquiry, as a component of systems design, provides a method of exploring systemic change and the design of educational systems from the perspectives of the facilitator of the change process, the invested participant in the change process, and the resistive participant in the change process. Systems design furnishes the construct within which to consider change, while narrative inquiry facilitates the design conversations that develop the processes, pathways and patterns that lead to the unfolding idealized school as a socially constructed reality of the participants.Rather than deal with discrete events individually, the personal stories that evolve in narrative inquiry allow people to build larger frames of reference and examine underlying assumptions and beliefs that guide our actions. Stories recreate experience in ways that allow the personal, cultural, and historical ground to remain present. As a relationship method, it emphasizes the human connections consistent with the interrelatedness found within members of a school. Using a three‐dimensional change model and narrative inquiry, this paper addresses the question: How can the stories embedded in the history context and culture of a school inform the change process? How can narrative inquiry mediate the process of moving across boundaries to the educational future? How can narrative inquiry identify symbolic boundaries that exist within an educational organization? Copyright © 2001 John Wiley & Sons, Ltd.