bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly potent side‐chain to side‐chain cyclized enkephalin analogues containing a carbonyl bridge: synthesis, biology and conformation
Authors: Pawlak Danuta , Oleszczuk Marta , Wójcik Jacek , Pachulska Maria , Chung Nga N. , Schiller Peter W. , Izdebski Jan
Published: August 2002

Six novel cyclic enkephalin analogues have been synthesized. Cyclization of the linear peptides containing basic amino acid residues in position 2 and 5 was achieved by treatment with bis(4‐nitrophenyl)carbonate. It was found that some of the compounds exibit unusually high µ‐opioid activity in the guinea pig ileum (GPI) assay. The 18‐membered analogue cyclo(Nε,Nβ′‐carbonyl‐𝒹‐Lys2,Dap5)enkephalinamide turned out to be one of the most potent µ‐agonists reported so far. NMR spectra of the peptides were recorded and structural parameters were determined. The conformational space was exhaustively examined for each of them using the electrostatically driven Monte Carlo method. Each peptide was finally described as an ensemble of conformations. A model of the bioactive conformation of this class of opioid peptides was proposed. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Investigation of penetratin peptides Part 1. The environment dependent conformational properties of penetratin and two of its derivatives
Authors: Czajlik András , Meskó Eszter , Penke Botond , Perczel András
Published: August 2002

The homeodomain, the DNA‐binding domain of Antennapedia homeoprotein, is composed of three α‐helices and one β‐turn between helices II and III. Its third helix from the N‐terminal (helix III) can translocate through the cell membrane into the nucleus and can be used as an intracellular vehicle for the delivery of oligopeptides and oligonucleotides. To the best of our knowledge, this helix III, called penetratin, which consists of 16 amino acids, is internalized by cells in a specific, non‐receptor‐mediated manner. For a better understanding of the mechanism of the transfer, the structure of penetratin was examined in both extracellular matrix‐mimetic and membrane‐mimetic environments; 1H‐NMR and CD spectroscopic measurements were performed in mixtures of TFE/water with different ratios. The molecular conformations of two analogue peptides [(6,14‐Phe)‐penetratin and a 12 amino acid penetratin derivative (peptide 3)] were also studied. An atomic level comprehensive analysis of penetratin and its two analogues was performed. In a membrane‐mimetic solvent system (TFEd2/water = 9 : 1), on the basis of 553 distance restraints, the 4–12 region of penetratin exhibits a bent, irregular helical structure on NMR examination. Interactions between hydrophobic amino acid residues in conjunction with H‐bonds stabilize the secondary structure of the molecule. Thus, both derivatives adopt a helix‐like conformation. However, while (6,14‐Phe)‐penetratin displays both α‐helical and 310‐helical features, the structure of peptide 3 is predominantly a 310‐helix. Of the three peptides, surprisingly (6,14‐Phe)‐penetratin has the largest helical content. An increase in the polarity of the molecular environment gradually disintegrates these helix‐like secondary structures. In a highly aqueous molecular system (TFEd2/water = 1 : 9), the fast exchange of multiple conformers leads to too few distance restraints being extracted, therefore the NMR structures can no longer be determined. The NMR data show that only short‐range order can be traced in these peptides. Under these conditions, the molecules adopt nascent helix‐like structures. On the other hand, CD spectra could be recorded at any TFE/water ratio and the conformational interconversion could therefore be monitored as a function of the polarity of the molecular environment. The CD data were analysed comprehensively by the quantitative deconvolution method (CCA+). All three penetratin peptides display helical conformational features in a low dielectric medium, with significant differences as a function of their amino acid composition. However, these conformational features are gradually lost during the shift from an apolar to a polar molecular environment. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Determination of actions due to fire: recent developments in Bayesian risk assessment of structures under fire
Authors: Gulvanessian H. , Holický M.
Published: August 2002

It is well recognized that the probability of fire start and conditional probability of fire flashover, given fire starts, may be expected in a given building within a broad range, depending on the applied fire safety system. Within the fire safety system the scale of active fire protection can be used to determine the design fire load. Similarly the probability of structural failure and extent of possible injuries from a fire depend considerably on the system of structural protection and arrangement of escape routes. Thus, risk assessment of structures under fire should be based on probabilistic concepts, taking into account various conditional probabilities, for example the proportion of fully developed fires of all started fires, i.e. the conditional probability that of fire flashover, provided that fire has started.

It appears that Bayesian causal (belief) networks, supplemented by appropriate input data, may provide an effective tool to analyse the significance of various characteristics of a fire safety system in terms of the resulting probability of flash over and other unfavorable consequences. Moreover, Bayesian networks, supplemented by decision nodes and a number of utility nodes (influence diagram), make it possible to estimate the expected total risk for both the buildings and their occupants and the actions due to the fire.

This review paper indicates that application of Bayesian causal (belief) networks may improve assessment of expected total risk, taking into account significant fire safety measures, including structural protection and arrangements of escape routes.
Background to fatigue load models for Eurocode 1: Part 2 Traffic Loads
Authors: Croce Pietro
Published: August 2002

The paper deals with background studies on definition and calibration of fatigue traffic load models for road bridges in Eurocode 1: Part 2 Traffic Loads on Bridges. Starting from real traffic data measurements, the derivation of the load models is illustrated step by step, emphasizing the peculiarities of the calibration methods adopted in prenormative research. The basic assumptions as well as the main features, the accuracy and the philosophy of each load model are discussed, and important questions pertaining to vehicle interactions, not fully clarified in the Eurocode, are tackled and solved in a general way, in the framework of queueing theory.
Flavonoids—a new direction for the treatment of fluid retention?
Authors: Christie Samantha , Walker Ann F. , Lewith George T.
Published: August 2002

Flavonoid extracts are important for the health of the micro‐blood vessel network and are clinically exploited in this way by medical herbalists and physicians in mainland Europe. In the present review, we provide preliminary evidence that suggests that plant flavonoid extracts from dietary sources facilitate the repair of vessel damage responsible for ‘small blood vessel permeability’. Correction of this pathophysiological abnormality is known to lead to a reduction in symptoms of diffuse benign fluid retention including swollen limbs, fingers, breasts and the tissue surrounding the eye area. There is currently little orthodox treatment for this type of fluid retention except diuretics which are not without side effects and fail to address the underlying cause of the disorder. This paper marshals available data including some preliminary studies that suggest that detailed scientific study of this clinical area and its treatment through flavonoid intervention is warranted. Copyright © 2001 John Wiley & Sons, Ltd.
Chemical and biological investigations on Zizyphus spina‐christi L.
Authors: Shahat Abdelaaty A. , Pieters Luc , Apers Sandra , Nazeif Naglaa M. , Abdel‐Azim Nahla S. , Berghe Dirk Vanden , Vlietinck Arnold J.
Published: August 2002

Different extracts and fractions of the leaves, fruits and seeds of Zizyphus spina‐christi L. grown in Egypt were investigated in vitro for their antiviral, antifungal and antibacterial activities. The flavonoids quercetin, hyperoside, rutin and quercetin‐3‐O‐[β‐xylosyl‐(1–2)‐α‐rhamnoside] 4′‐O‐α‐ rhamnoside) were isolated. Copyright © 2001 John Wiley & Sons, Ltd.
Paperboard packages exposed to static loads–finite element modelling and ­experiments
Authors: Beldie Liliana , Sandberg Göran , Sandberg Lars
Published: August 2002

The aim of this study was to analyse the mechanical behaviour of paperboard packages subjected to static compressive loads. The study was divided in three parts and experiments and finite element analysis conducted for each part. First, a panel of paperboard was subjected to edge compressive loading as a means of checking the material model. Second, the package was cut into segments and each segment was subjected to compression in order to determine the contribution of the different parts to the overall behaviour of the package. Third, a whole package loaded in compression was studied. In the finite element simulations, the paperboard was modelled as an orthotropic, linear, elastic–plastic laminate. The study utilized a non‐linear finite element analysis, based on the plasticity of the material and large displacements. The results show that the middle segment of the package exhibits a higher stiffness than that of the upper and lower package segments and that of the whole package, which leads to the conclusion that the low initial stiffness of the package is a consequence of the low stiffness of the upper and lower corners, i.e. of the horizontal creases. Copyright © 2001 John Wiley & Sons, Ltd.
Standard operating procedures in clinical research: a beginner's guide
Authors: Hamrell Michael R. , Wagman Bruce
Published: August 2002

A consistent concern when implementing a quality system for clinical research is the level of standardization and organization to impose within each department. Standard operating procedures (SOPs) and operational guidelines (OGs), describing how each member of the clinical research team should conduct the various activities associated within their department, are the framework for any quality system. SOPs provide instructions and guidance to the user on what to do and what is expected of them. Standardized procedures are important not only to provide direct instruction but also to maintain consistency between various parts of an organization involved with the conduct and reporting of clinical trials. The increased use of multinational clinical trials requires the use of a standardized approach to maintain consistent quality and results in a drug development programme. In this article, an introduction to quality systems, SOPs and how they can help in the conduct of clinical trials, provides an overview for those persons new to clinical research and the role of SOPs. Copyright © 2001 John Wiley & Sons, Ltd.
Sizing fixed effects for computing power in experimental designs
Authors: Oehlert Gary W. , Whitcomb Pat
Published: August 2002

Power tells us the probability of rejecting the null hypothesis for an effect of a given size and helps us select an appropriate design prior to running the experiment. The key to computing power for an effect is determining the size of the effect. We describe a general approach for sizing effects that covers a wide variety of designs including factorials with categorical levels, response surfaces, mixtures and crossed designs. Copyright © 2001 John Wiley & Sons, Ltd.
Fundamental quantum QSAR (Q2SAR) equation: extensions, nonlinear terms, and generalizations within extended Hilbert–Sobolev spaces
Authors: Carbó‐Dorca Ramon , Besalú Emili
Published: August 2002

The fundamental quantum QSAR (Q2SAR) equation is analyzed from the point of view of the expectation value structure in extended Hilbert and Sobolev spaces. A new general Q2SAR picture emerges. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 88: 167–182, 2002
Variational Monte Carlo calculations for some cations and anions of the first‐row atoms using explicitly correlated wave functions
Authors: Gálvez F. J. , Buendía E. , Sarsa A.
Published: August 2002

The variational Monte Carlo method is applied to calculate ground‐state energies of some cations and anions of the first‐row atoms. Accurate values providing between 80 and 90% of the correlation energy are obtained. Explicitly correlated wave functions including up to 42 variational parameters are used. The nondynamic correlation due to the 2s − 2p near degeneracy effect is included by using a multideterminant wave function. The variational free parameters have been fixed by minimizing the energy that has shown to be a more convenient functional than the variance of the local energy, which is the most commonly employed method in variational Monte Carlo calculations. The energies obtained improve previous works using similar wave functions. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/qua.10125
Exact solution of the relativistic dynamics of a spin‐½ particle moving in a homogeneous magnetic field
Authors: Datta Sambhu N. , Misra Anirban
Published: August 2002

The relativistic dynamics of one spin‐½ particle moving in a uniform magnetic field is described by the Hamiltonian \documentclass{article}\pagestyle{empty}\begin{document}$\mathbf{h}^{0}_{D}(\pi)=c\alpha\cdot\pi+\beta mc^{2}$\end{document}. The discrete (and semidiscrete) eigenvalues and the corresponding eigenspinors are in principle known from the work of Dirac, Rabi, and Bloch. These are extensively reviewed here. Next, exact solutions are worked out for the recoil dynamics in relative coordinates, which involves the Hamiltonian \documentclass{article}\pagestyle{empty}\begin{document}$\mathbf{h}^{0}_{D}(-\mathbf{k})=-c\alpha\cdot\mathbf{k}+\beta mc^{2}$\end{document}. Exact solutions are also explicitly calculated in the case where the spin‐½ particle has an anomalous magnetic moment such that its Hamiltonian is given by \documentclass{article}\pagestyle{empty}\begin{document}$\mathbf{h}_{D}(\pi)=\mathbf{h}^{0}_{D}(\pi)-\beta\mu_{\mathrm{ano}}\sigma\cdot\mathbf{B}$\end{document}. Similar exact solutions are derived here when the recoiling particle has an anomalous magnetic moment, that is, the eigenvalues and eigenspinors of the Hamiltonian \documentclass{article}\pagestyle{empty}\begin{document}$\mathbf{h}_{D}(-\mathbf{k})=\mathbf{h}^{0}_{D}(-\mathbf{k})-\beta\mu_{\mathrm{ano}}\sigma\cdot\mathbf{B}$\end{document} are explicitly obtained. The diagonalized and separable form of the Hamiltonian hD(π), written as \documentclass{article}\pagestyle{empty}\begin{document}$\tilde{\mathbf{h}}_{D}(\pi)$\end{document}, has exceedingly simple forms of eigenspinors. Similarly, the diagonalized and separable form of the operator hD(−k), written as \documentclass{article}\pagestyle{empty}\begin{document}$\tilde{\mathbf{h}}_{D}(-\mathbf{k})$\end{document}, has very simple eigenspinors. The importance of these exact solutions is that the eigenspinors can be used as bases in a calculation involving many spin‐½ particles placed in a uniform magnetic field. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 209–217, 2001
Quadrupole coupling constants CQQ for 2H, 27Al, and 17O atoms calculated at the periodic Hartree–Fock level for understanding the geometry of H‐form aluminosilicates
Authors: Larin A. V. , Vercauteren D. P.
Published: August 2002

The coordinates of crystallographically different atomic types of Si–O(H)–Al Brönsted centers within five H‐form aluminosilicate frameworks—ABW, CAN, CHA, EDI, and NAT—were optimized using a full periodic ab initio Hartree–Fock scheme at the STO‐3G level. Single‐point calculations were then carried out at the ps‐21G* (Al, Si)/6‐21G*(O, H) and 6‐21G*(Al, Si)/6‐21G*(O, H) levels to obtain the 2H, 27Al, and 17O respective nuclear quadrupole coupling constants and electrostatic field gradient anisotropies. The latter are discussed and compared to the experimental values measured for different zeolites. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 182–192, 2001
Phenol O–H bond dissociation energy in water clusters
Authors: Cabral do Couto P. , Guedes R. C. , Costa Cabral B. J. , Martinho Simões J. A.
Published: August 2002

We are reporting ab initio and density functional theory (DFT) calculations for the phenol O–H bond dissociation energy in the gas phase and in phenol–water clusters. We have tested a series of recently proposed functionals and verified that DFT systematically underestimates the O–H bond dissociation energy of phenol. However, O–H bond dissociation energies in water clusters are in reasonable agreement with experimental data for phenol in solution. We have evaluated electronic difference densities in phenol–water, phenoxy–water, and water, and we are suggesting that the representation of this quantity gives an interesting picture of the electronic density rearrangement induced by hydrogen bond interactions in phenol–water clusters. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
On Uniform (1≤Ii≤3) n‐fold {∣IouterM(i1⋅⋅⋅in)〉} dual tensorial sets, spin irreps from SU(3≤m)×𝒮n⊃⋅⋅⋅⊃𝒮n weight sets: a direct role for 𝒩(λ⊢n)‐partitional catalogs of 𝒮n combinatorics in spin physics
Authors: Temme F. P.
Published: August 2002

A direct systematic approach is given to the derivation of outer M‐labeled ∣IM(⋅)〉 dual (spin) irreps for identical higher nuclear spin ensembles. This stresses the essential role of multipartite partitions in spin physics and the value of algorithmic tableau‐based decompositions of 𝒮n combinatorics. Additional purely 𝒮n projective modeling techniques for the numbers of independant ensemble scalar invariants are discussed briefly. Such uniform inner rank dual group basis sets (spin representations) are as central to NMR as they are to all isotopomer CNP aspects of spectral weighting. Three specific applications are presented: one involving \documentclass{article}\pagestyle{empty}\begin{document}$[A]_{6}^{(I_{i})}$\end{document} systems, whereas the others treat 2H‐cubane and the spin subensembles of the trans‐[2H11B]10(CH2)2 carborane isotopomer to illustrate recent algorithmic roles specifically for “sst” (𝒮n) encoding in (quantized) spin physics and quantum‐Liouville NMR spin dynamics. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002
Computational characterization of nucleotide bases: Molecular surface electrostatic potentials and local ionization energies, and local polarization energies
Authors: Murray Jane S. , Peralta‐Inga Zenaida , Politzer Peter , Ekanayake Kaushalya , LeBreton Pierre
Published: August 2002

Electrostatic potentials and local ionization energies have been computed at the HF/6‐31G* level on the molecular surfaces of the five nucleotide bases. The potentials are analyzed in terms of their most positive and negative values as well as several statistically defined quantities that reflect their patterns over the entire surface. Considerable charge separation and variability are found for all five molecules. The results are consistent with the base pairing that is known to occur. The observed reactive behavior toward electrophiles can be interpreted in terms of the complementary roles of the surface potential and the local electron lability. Local polarization energies, corresponding to a test charge being placed at specific points above the molecules, are also calculated (HF/6‐31+G*), and their relationship to the local ionization energies is examined. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 245–254, 2001
Toroidal and spherical fullerene‐like molecules with only pentagonal and heptagonal faces
Authors: László István , Rassat André
Published: August 2002

The stability of toroidal and spherical carbon cage structures, constructed from five‐ and seven‐membered rings, was studied using tight binding, Tersoff and Brenner potential based methods. A special tiling is presented for the torus of minimal strain energy. In order to make comparison between the results of various calculations we defined the σAB square root average bond distance difference between the methods A and B. By addition of six‐membered rings to the C40 torus we obtained a toroidal C60 carbon cage molecule. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 136–139, 2001
Dicoordinate boron and phosphorus. HBCN− and HPCN− case study
Authors: Liebman Joel F. , Černušák Ivan , Miková Andrea
Published: August 2002

Using ab initio calculations we predict anionic and neutral isomers of dicoordinate boron and phosphorus, HE(CN−), HE(CN), (E=B, P). Geometries [at the MBPT(2)/aug‐cc‐PVTZ level], electron affinities, singlet–triplet (ST) splittings, and PH/BH affinities of CN− (at coupled‐clusters level) are presented. For the HBCN− chain the triplet, while for the HPCN− chain the singlet is the ground state. The rather small HEB (or HEN) bonding angles in acyclic isomers are explained on the basis of the molecular orbital (MO) picture and 1,3 interactions between hydrogen and carbon/nitrogen. Both cyanoboryl anion and cyanoboryl radical form also the ring (

magnified image

‐ being aromatic with two π electrons) but for the cyanophosphide the corresponding ring does not constitute a minimum on the potential energy surface. It has four π electrons and therefore is antiaromatic. Our best electron affinity estimate for HPCN is 2.44 eV, for HBCN it is 0.15 eV, while the corresponding values for the ST splittings of anions are 2.80 and −0.04 eV, respectively. Huge effects of electron correlation on calculated properties of these molecules are discussed. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 140–148, 2001
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

N2 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

A 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

Proteins 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

The 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

Tetrathiofulvalene 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

The 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

Ion 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

The 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

A 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

Two 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

A 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

This 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

Bifunctionally 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

Cleaning 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

Pure 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

Continuity 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

A 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

This 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

Narrative 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.
Perioperative radiotherapy and concurrent radiochemotherapy in rectal cancer
Authors: Rödel Claus , Sauer Rolf
Published: August 2002

Combined modality treatment is the recommended standard adjuvant therapy for patients with locally advanced rectal cancer in the United States and Germany. During the last decade substantial progress has been made in treatment modalities, and surgical management currently includes a broad spectrum of operative procedures ranging from radical operations to innovative sphincter‐preserving techniques. Specialized groups have reported excellent local control rates with total mesorectal excision (TME) alone. New and improved radiation techniques (conformal and intraoperative radiotherapy) and innovative schedules (protracted intravenous and chronomodulated infusion) and combinations (oxaliplatin and irinotecan) of chemotherapy may have the potential to further increase the therapeutic benefit of adjuvant treatment. Moreover, the basic issue of timing (pre‐ or postoperative) within a multimodal regimen is currently being addressed in prospective trials. Evidently there is a need to question the current monolithic approaches, which were established by studies conducted more than a decade ago. It is also under discussion whether to apply the same schedule of postoperative radiochemotherapy to all patients with stage II/III rectal cancer, or to give preoperative intensive short‐course radiation according to the Swedish concept for all patients with resectable rectal cancer irrespective of tumor stage and treatment goal (e.g., sphincter preservation). This review discusses different irradiation settings in more recent and ongoing studies of perioperative radiotherapy for rectal cancer, and focuses on the issue of which patient should receive radiotherapy (if at all), and if so, how and when. Semin. Surg. Oncol. 20:3–12, 2001. © 2001 Wiley‐Liss, Inc.
1‐, 2‐, and 3‐dimensional polyphenylenes—from molecular wires to functionalised nanoparticles
Authors: Grimsdale Andrew C. , Müllen Klaus
Published: August 2002

Polyphenylenes, ranging from one‐dimensional wire‐like conjugated polymers to two‐dimensional disc‐shaped polyaromatic hydrocarbons and three‐dimensional sphere‐like dendrimers, have been prepared using methods that allow synthetic control of their molecular and supramolecular order in order to optimise their physical, especially optical and electrical, properties. 1D‐conjugated polymers can be used as emitting materials in LEDs, with their colours tuned so as to give emission across the whole visible spectrum. Their supramolecular order can be manipulated by attachment of bulky sidechains to suppress aggregation, and by formation of rod‐coil block copolymers. 2D polycyclic aromatic hydrocarbons form stable columnar mesophases with high charge carrier mobilities. Their size, shape, and substitution patterns can be altered so as to maximise their intra‐ and intercolumnar order. 3D polyphenylene dendrimers can be prepared in ways that enable control of their shape, and their surfaces can be selectively functionalised in ways that permit them to act as functionalised nanoparticles. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:243–257, 2001
The Caracol Time Travel Project
Authors: Hughes Charles E. , Michael Moshell J. , Reed Dean , Chase Diane Z. , Chase Arlen F.
Published: August 2002

Virtual drama is based on the use of a shareable virtual world as a stage setting, with avatars controlled by actors and audience members. The Caracol Time Travel Project was an experiment in the use of virtual drama for learning about archaeology. Eighteen undergraduate students at the University of Central Florida used a locally developed Java‐based system for sharing VRML worlds. They designed and constructed a virtual drama to teach basic concepts of Mesoamerican archaeology and the cultural history of the ancient Maya for middle schools. This paper presents their story design and details of the system we developed to support interaction in this shared virtual world. We then discuss performance issues, lessons learned and newer features that we did not have available at the time. Copyright © 2001 John Wiley & Sons, Ltd.