bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the basicity of substituted dimethylamines in different solvents by theoretical descriptors
Authors: Headley Allan D. , Nam Jaewook
Published: October 2002

By using theoretically determined descriptors in quantitative structure–property relationships, quick and good a priori predictions of molecular properties can be accomplished. In this study, theoretical linear solvation energy relationship descriptors are used to analyze structural effects that contribute to the basicity variation of substituted dimethylamines in different solvents. A multilinear regression (MLR) analysis approach is used to generate equations and, owing to the goodness of the ‘fit’ of the different MLR equations, the descriptors used account very well for the structural effects that determine the relative basicity of dimethylamines. Good agreement is obtained between the basicity values predicted by this method and the experimental basicity values of 14 substituted dimethylamines in eight solvents and the gas phase. The Lewis basicity ϵB and the polarizability/dipolarity πi are the important factors that contribute to basicity variation. For the basicity of NCCH2N(CH3)2, a good prediction was not achieved and a discussion is presented. Copyright © 2001 John Wiley & Sons, Ltd.
Reactive intermediates via Fourier transform mass spectrometry
Authors: Kass Steven R. , Broadus Katherine M.
Published: October 2002

A new method for the selective preparation of radical anions in the gas phase is described. Dicarboxylate anions are generated in a Fourier transform mass spectrometer via electrospray ionization, and both carboxylates and an electron are removed to afford odd‐electron anions via sequential fragmentations. Energetic measurements on these species enable the heats of formation of neutral compounds to be determined. The heats of hydrogenation of benzocyclobutadiene and acenaphthyne are used to illustrate this methodology and the antiaromaticity and/or strain energy of these molecules are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Historical perspectives on living anionic polymerization
Authors: Smid Johannes
Published: October 2002

A brief overview of the role that Dr. Michael Szwarc has played in unraveling the mechanism of living anionic polymerization is presented. Emphasis is placed on the different ionic species that control the propagation reaction in ether‐type solvents. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2101–2107, 2002
Synthesis of block copolymers by the transformation of cationic polymerization into reversible atom transfer radical polymerization
Authors: Cianga Ioan , Hepuzer Yesim , Serhatli Ersin , Yagci Yusuf
Published: October 2002

Azo‐containing polytetrahydrofuran (PTHF) obtained by cationic polymerization was used as a macroinitiator in the reverse atom transfer radical polymerization (RATRP) of styrene and methyl acrylate in conjunction with CuCl2/2,2′‐bipyridine as a catalyst. Diblock PTHF–polystyrene and PTHF–poly(methyl acrylate) were obtained after a two‐step process. In the first step of the reaction, stable chlorine‐end‐capped PTHF was formed with the thermolysis of azo‐linked PTHF at 65–70 °C in the presence of the catalyst. Heating the system at temperatures of 100–110 °C started the polymerization of the second monomer, which resulted in the formation of block copolymers. The decomposition behavior of the azo‐linked PTHF and the structure of the block copolymers were determined by 1H NMR and gel permeation chromatography (GPC). Kinetic studies and GPC analyses further confirmed the controlled/living nature of the RATRP initiated by the polymeric radicals. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2199–2208, 2002
Synthesis of comb‐branched polyacrylamide with cationic poly[(2‐dimethylamino)ethyl methacrylate dimethylsulfate] quat
Authors: Zeng Faquan , Shen Youqing , Zhu Shiping
Published: October 2002

Comb‐branched polyelectrolytes with polyacrylamide backbones and poly[(2‐dimethylamino)ethyl methacrylate methylsulfate] (polyDMAEMA‐DMS) side chains were prepared by free‐radical macromonomer polymerization. PolyDMAEMA‐DMS macromonomers bearing terminal styrenic moieties were synthesized by living anionic polymerization with lithium 4‐vinylbenzylamide (LiVBA) and lithium N‐isopropyl‐4‐vinylbenzylamide (LiPVBA) as initiators. In the presence of LiCl, LiPVBA initiated a living polymerization of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and produced polymers with well‐controlled molecular weights and low polydispersities. LiVBA could not directly initiate DMAEMA polymerization. After being capped with two units of dimethylacrylamide, DMAEMA polymerized with an initiator efficiency of 63%. The quaternization of the poly[(2‐dimethylamino)ethyl methacrylate] macromonomer with dimethyl sulfate yielded the cationic polyDMAEMA‐DMS macromonomer. The polyDMAEMA‐DMS macromonomer had a much higher reactivity than acrylamide in free‐radical polymerization. This might have been due to the formation of polyDMAEMA‐DMS micelles in the polymerization system. The high macromonomer reactivity caused composition drift in a batch process. A semibatch method with a constant polyDMAEMA‐DMS feed rate was used to control the copolymer composition. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2394–2405, 2002
Synthesis and characterization of polystyrene‐b‐poly (1,2‐isoprene‐ran‐3,4‐isoprene) block copolymers with azobenzene side groups
Authors: Hayakawa Teruaki , Horiuchi Shin , Shimizu Hiroshi , Kawazoe Tadashi , Ohtsu Motoichi
Published: October 2002

Polystyrene‐b‐poly(1,2‐isoprene‐ran‐3,4‐isoprene) block copolymers with azobenzene side groups were synthesized by the esterification of azobenzene acid chloride with polystyrene‐b‐hydroxylated poly(1,2‐isoprene‐ran‐3,4‐isopenre) block copolymers for creating new photochromic materials. The resulting block copolymers with azobenzene side groups were characterized for structural, thermal, and morphological properties. IR and NMR spectroscopies confirmed that the polymers obtained had the expected structures. Differential scanning calorimetric measurements by heating runs clearly showed the glass transitions of polystyrene and polyisoprene main chains and two distinct first‐order transitions at temperatures of azobenzene side groups around 48 and 83 °C. The microstructure of these block copolymer films was investigated using both transmission electron microscopy (TEM) and near‐field optical microscopy (NOM). TEM images revealed typical microphase‐separated morphologies such as sphere, cylinder, and lamellar structures. The domain spacing of microphase‐separated cylindrical morphology in the NOM image agreed with that of the TEM results. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2406–2414, 2002
Synthesis of new fluorinated allyl ethers for the surface modification of thiol–ene ultraviolet‐curable formulations
Authors: Sangermano M. , Bongiovanni R. , Malucelli G. , Priola A. , Harden A. , Rehnberg N.
Published: October 2002

Thiol–ene photocurable systems based on a trifunctional thiol [trimethylolpropane tris‐(3‐mercaptopropanoate)] and two different multifunctional allyl ethers (trimethylolpropane triallyl ether and Boltorn U2, an allyl functional dendritic polyester) were examined. To these systems, small amounts (<1 wt %) of fluorinated allyl ethers were added for the modification of their surface properties. Two new fluorinated allyl ethers, 1H,1H‐perfluoro‐1‐heptylallyl ether and 1H,1H‐perfluoro‐1‐decylallyl ether, were synthesized for this purpose by allylation of the corresponding 1H,1H‐perfluoro alcohols. The fluorinated monomers, despite their very low concentrations, caused sharp changes in the surface properties of the films and in the solvent resistance without any changes in the curing conditions and bulk properties. Completely hydrophobic surfaces were obtained (as a result of the selective enrichment of the fluorinated monomers on the film surfaces) that depended on the monomer structure and its concentration. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2583–2590, 2002
Synthesis and characterization of halogen‐containing poly(ether ketone ketone)s
Authors: García Carolina , Lozano Ángel E. , de la Campa José G. , de Abajo J.
Published: October 2002

A series of novel poly(ether ketone ketone)s (PEKKs) were synthesized from diphenyl ether and isophthaloyl chloride derivatives such as 5‐halo‐ and 5‐tert‐butyl‐isophthaloyl chloride. The aromatic electrophilic substitution route to polyketones was a convenient route for the preparation of the polymers in high yields via precipitation polycondensation at a low temperature with aluminum trichloride as a catalyst. High molecular weight PEKKs were achieved with number‐average molecular weights of 15,000–100,000 g/mol for polymers that showed good solubility in organic solvents. The presence of substituents greatly modified the spectroscopic features in comparison with those of unsubstituted isophthaloyl poly(ether ketone ketone)s, particularly for the series containing halogens, for which significant variations of the chemical shifts in both 1H and 13C NMR spectra were observed; these shifts could be related to the nature of the halogen. Thermal properties were also affected by the presence of pendent substituents, with clear enhancements of the glass‐transition temperatures, which could be ascribed to the nature and bulkiness of the substituents. Thermogravimetric analyses showed that the new polymers had good thermal resistance, although an important drop in thermal resistance was observed for polymers bearing large halogen atoms, such as bromine and iodine. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2601–2608, 2002
Synthesis and characterization of luminescent polyethers with 2,5‐distyrylthiophene and aromatic oxadiazole chromophores
Authors: Chen Yun , Huang Yu‐Yi , Wu Tzi‐Yi
Published: October 2002

Two new luminescent copolyethers (P1 and P2) with isolated 2,5‐distyrylthiophene‐emitting segments and electron‐transporting 2,5‐diphenyl‐1,3,4‐oxadiazole chromophores were successfully synthesized by the Horner–Wadworth–Emmons reaction. The solubility, optical, and electrochemical properties of the polymers were investigated and correlated with nonlinear thiophene and 1,3,4‐oxadiazole groups. P2 with pendant 1,3,4‐oxadiazole was soluble in common organic solvents such as chloroform, tetrahydrofuran, and C2H2Cl4. Thermogravimetric analysis and differential scanning calorimetry showed that the copolyethers were thermally stable below 345 °C, with glass‐transition temperatures higher than 110 °C. They were yellow‐greenish emitting materials with a band gap of 2.57–2.58 eV estimated from the onset absorption. Incorporating the thiophene moiety narrowed the band gaps of the copolyethers. The photophysical and electronic properties of the polymer and the preliminary electroluminescent device made from the polymer demonstrate that the polymer may be a potential candidate material for the fabrication of polymeric light‐emitting devices. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2927–2936, 2002
Application of ketenes to well‐defined polyester synthesis (4): End‐capping reactions in living anionic polymerization of ethylphenylketene
Authors: Sudo Atsushi , Endo Takeshi
Published: October 2002

End‐capping reactions of a living polyester, obtained by anionic polymerization of ethylphenylketene (EPK), were carried out. As end‐capping reagents, electrophiles such as alkyl halide and acyl halide were successfully used. Reactivity of the terminal enolate and the resulting terminal structures were elucidated by model reactions, using lithium enolates having low molecular weights, obtained by an equimolar reaction of EPK with butyllithium. Polymerization of EPK by lithium alkoxide and the subsequent end‐capping reaction afforded the corresponding polyester having functional groups at both chain ends and a narrow molecular weight distribution. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3103–3111, 2002
Novel spherical Ziegler–Natta catalyst for polymerization and copolymerization. I. Spherical MgCl2 support
Authors: Ye Zhao‐Yang , Wang Li , Feng Lian‐Fang , Gu Xue‐Ping , Chen Hai‐Hua , Zhang Pu‐Yu , Pan Jie , Jiang Shan , Feng Lin‐Xian
Published: October 2002

Spherical MgCl2 adducts used as supports for a Ziegler–Natta catalyst for olefin polymerization were prepared by the general precipitation method. The influence of MgCl2/EtOH (mol/mol) and the dispersion speeds on the particle size (PS) and particle size distribution (PSD) were investigated. It was found that the former played a trivial role in controlling the PS and PSD, and the latter was the key factor. In particular, the influence of ethanol on the crystal structure was further examined, with consideration given to the performance of the supported Ziegler–Natta catalyst. It was believed that the reactions between MgCl2 and ethanol had a controlling effect on the destruction of the original anhydrous MgCl2, which was the key point in the preparation of suitable supports for the latest generation Ziegler–Natta catalyst. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3112–3119, 2002
Morphology and orientation during the deformation of segmented elastomers studied with small‐angle X‐ray scattering and atomic force microscopy
Authors: Sauer Bryan B. , McLean R. Scott , Brill Donald J. , Londono David J.
Published: October 2002

Small‐angle X‐ray scattering (SAXS), atomic force microscopy (AFM), and other techniques were combined in a study of segmented thermoplastic elastomers (Pebax) containing poly(tetramethylene oxide) soft segments and hard blocks of nylon‐12. AFM was used to provide real‐space resolution of the morphology during tensile elongation and after subsequent relaxation. Nanofibril formation, starting at strains of about 1.5×, was characterized in detail, showing the evolution of the number, orientation, and size of these highly stressed load‐bearing fibrils that dominated the mechanical properties. AFM results were combined with two‐dimensional SAXS data to develop a model considering the breakup of the original ribbonlike nylon‐12 lamellae in combination with progressive reformation and orientation of highly stressed fibrils. The complex changes in the two‐dimensional SAXS images included a distorted arc pattern due to increased spacing of the lamellae in the stretch direction at low strains, with an evolution to completely different patterns dominated mainly by intrafibrillar and interfibrillar scattering contributions. Between stretch ratios of 1.5 and 2.3× original lamellae were progressively broken up, and by 3.2×, all lamellae independent of the initial orientation were broken into smaller crystals with low aspect ratios. The results were combined with differential scanning calorimetry and birefringence data taken on films under strain to obtain insight into the microscopic basis for strain softening and plastic deformation in Pebax and related segmented polymers. Birefringence cycling with strain provided a consistent picture with the other techniques for understanding the redistribution of stress on a nanoscopic scale during deformation and relaxation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1727–1740, 2002
Structural and rheological properties of hydrophobically modified alkali‐soluble emulsion solutions
Authors: Knaebel A. , Skouri R. , Munch J. P. , Candau S. J.
Published: October 2002

Scattering and rheological experiments were carried out on hydrophobically modified alkali‐soluble emulsion solutions at pH ∼ 7.3 as a function of the polymer concentration. The light scattering experiments revealed the existence of a liquidlike order for concentrations below approximately 0.1 × 10−2g cm−3corresponding approximately to the close packing of microgels particles. Above this concentration, the zero‐shear viscosity rose sharply, whereas the ordering disappeared progressively. The results are discussed within the framework of gelation models of associating polymers. Diffusing wave spectroscopy experiments provided estimates of the high‐frequency modulus. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1985–1994, 2002
Influence of gel composition on the solubility parameter of poly(2‐hydroxyethyl methacrylate‐itaconic acid) hydrogels
Authors: Çaykara Tuncer , Özyürek Cengiz , Kantoğlu Ömer , Güven Olgun
Published: October 2002

The solubility parameters of pure poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(2‐hydroxyethyl methacrylate/itaconic acid) [P(HEMA/IA)] hydrogels were determined by 20 solvents with various solubility parameters in swelling experiments. The solubility parameter of pure PHEMA was 26.93 ± 0.46 (MPa)1/2. The effect of mole percentages of itaconic acid (IA) in P(HEMA/IA) hydrogels on the solubility parameter was investigated. The measured values were compared to literature and solubility values theoretically determined by group contribution values of van Krevelen and Hoy. The incorporation of IA into the hydrogel system slightly increased the solubility parameter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1995–2003, 2002
Effect of chemical activity jumps on the viscoelastic behavior of an epoxy resin: Physical aging response in carbon dioxide pressure jumps
Authors: Alcoutlabi Mataz , Briatico‐Vangosa Francesco , McKenna Gregory B.
Published: October 2002

We report the results from tensile creep tests performed on an epoxy resin in the presence of carbon dioxide at different pressures (Pco2) and at a constant temperature below the glass‐transition temperature. Time‐Pco2 superposition was applied to the data to account for the plasticization effect because of the interaction between the carbon dioxide molecules and the polymer. In addition, physical aging of the epoxy films was investigated with sequential creep tests after carbon dioxide pressure down‐jumps at constant temperature and after temperature down‐jumps at constant carbon dioxide pressure. The isothermal pressure down‐jump experiments showed physical aging responses similar to the isobaric temperature down‐jump experiments. However, the aging rate for the CO2 jump was slightly lower than that for the temperature‐jump (T‐jump) experiments, and the retardation time for the Pco2‐jump experiments was up to 6.3 times longer than for the T‐jump conditions. The results are discussed in terms of classical physical aging and structural recovery frameworks, and speculation about the differences in the energy landscape resulting from the Pco2‐jump and T‐jump experiments is also made. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2050–2064, 2002
Ultimate tensile behavior of linear polyethylene solids
Authors: Nitta Koh‐Hei , Ishiburo Takashi
Published: October 2002

The influence of the elongation rate and temperature on the ultimate tensile properties of melt‐crystallized linear polyethylene solids was investigated, with a double‐edge‐notched specimen to avoid necking, in which uniform deformation could be assumed throughout the experiment. The data on ultimate properties such as the tensile strength and elongation at break for different temperatures could be superimposed, by shifts along the elongation rate axis, to give a master curve as a function of the time to rupture. The shift factors obtained from the superpositioning of both the tensile strength and ultimate strain took the form of the Williams–Landel–Ferry equation. As a result, the ultimate data provided a failure envelope curve that made it possible to predict rupture times when the tensile tests were conducted under any experimental conditions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2018–2026, 2002
Hypoglycemia due to adrenal suppression secondary to high‐dose nebulized corticosteroid
Authors: Dunlop K.A. , Carson D.J. , Shields M.D.
Published: October 2002

High‐dose inhaled corticosteroids, greater than 400 mcg per day of beclomethasone dipropionate or equivalent, can cause adrenal insufficiency, but a hypoglycemic crisis has not been reported with the use of nebulized corticosteroids. We describe a 21‐month‐old asthmatic boy who had a hypoglycemic seizure during a proven acute adrenal crisis secondary to high‐dose nebulized budesonide treatment. Pediatr Pulmonol. 2002; 34:85–86. © 2002 Wiley‐Liss, Inc.
Optimally informative backbone structural propensities in proteins
Authors: Solis Armando D. , Rackovsky S.
Published: October 2002

We use basic ideas from information theory to extract the maximum amount of structural information available in protein sequence data. From a non‐redundant set of protein X‐ray structures, we construct local‐sequence‐dependent [ϕ,ψ] distributions that summarize the influence of local sequence on backbone conformation. These distributions, approximations of actual backbone propensities in the folded protein, have the following properties: (1) They compensate for the problem of scarce data by an optimized combination of local‐sequence‐dependent and single‐residue specific distributions; (2) They use multi‐residue information; (3) They exploit similarities in the local coding properties of amino acids by collapsing the amino acid alphabet to streamline local sequence description; (4) They are designed to contain the maximum amount of local structural information the data set allows. Our methodology is able to extract around 30 cnats of information from the protein data set out of a total 387 cnats of initial uncertainty or entropy in a finely discretized [ϕ,ψ] dihedral angle space (18 × 18 structural states), or about 7.8%. This was achieved at the hexamer length scale; shorter as well as longer fragments produce reduced information gains. The automatic clustering of amino acids into groups, a component of the optimization procedure, reveals patterns consistent with their local coding properties. While the overall information gain from local sequence is small, there are some local sequences that have significantly narrower structural distributions than others. Distribution width varies from at least 20% less than the average overall entropy to at least 14% above. This spread is an expression of the influence of local sequence on the conformational propensities of the backbone chain. The optimal ensemble of local‐sequence‐specific backbone distributions produced is useful as a guide to structural predictions from sequence, as well as a tool for further explorations of the nature of the local protein code. Proteins 2002;48:463–486. © 2002 Wiley‐Liss, Inc.
Understanding protein structure‐function relationships in Family 47 α‐1,2‐mannosidases through computational docking of ligands
Authors: Mulakala Chandrika , Reilly Peter J.
Published: October 2002

Family 47 α‐1,2‐mannosidases are crucial enzymes involved in N‐glycan maturation in the endoplasmic reticula and Golgi apparati of eukaryotic cells. High‐resolution crystal structures of the human and yeast endoplasmic reticulum α‐1,2‐mannosidases have been recently determined, the former complexed with the inhibitors 1‐deoxymannojirimycin and kifunensine, both of which bind in its active site in the unusual 1C4 conformation. However, unambiguous identification of the catalytic proton donor and nucleophile involved in glycoside bond hydrolysis was not possible from this structural information. In this work, α‐D‐galactose, α‐D‐glucose, and α‐D‐mannose were computationally docked in the active site in the energetically stable 4C1 conformation as well as in the 1C4 conformation to compare their interaction energetics. From these docked structures, a model for substrate and conformer selectivity based on the dimensions of the active site was proposed. α‐D‐Galactopyranosyl‐(1→2)‐α‐D‐mannopyranose, α‐D‐glucopyranosyl‐(1→2)‐α‐D‐mannopyranose, and α‐D‐mannopyranosyl‐(1→2)‐α‐D‐mannopyranose were also docked into the active site with their nonreducing‐end residues in the 1C4 and E4 (representing the transition state) conformations. Based on the docked structure of α‐D‐mannopyranosyl‐E4‐(1→2)‐α‐D‐mannopyranose, the catalytic acid and base are Glu132 and Glu435, respectively. Proteins 2002;49:125–134. © 2002 Wiley‐Liss, Inc.
Existence of strictly diabatic basis sets for the two‐state problem
Authors: Kryachko Eugene S. , Varandas António J. C.
Published: October 2002

Some new properties of the nonadiabatic coupling elements are derived, in particular the orthogonality and gauge invariance of their longitudinal and transverse components. A method for constructing a strictly diabatic basis set that makes both the transverse and longitudinal components of the nonadiabatic coupling elements of the two‐state problem vanish identically and is based on introducing overlap between the electronic states in the vicinity of the crossing seam is proposed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Complexes of C60 fullerene with simple donor molecules: Theoretical study
Authors: Fomina Lioudmila , Reyes Abraham , Fomine Serguei
Published: October 2002

The complex formation between fullerene C60 and simple donor molecules such as dimethyl ether, dimethylamine, dimethylsulfide, furan, pyrrole, and thiophene has been studied applying the hybrid MP2/6‐31G(d′):PM3 ONIOM approach for geometry optimization. Local implementation of Møller–Plesset perturbation theory in combination with 6‐31G(d) and 6‐311G(d,p) basis sets was used for binding energies estimation of fullerene complexes. Two factors were found to contribute most to the complex stability: the polarizability and molecular volume of donor molecule. As follows from positive stabilization energies at the Hartree–Fock level, the stabilization of fullerene complexes is entirely due to dispersion interactions in accordance with available experimental data. The calculations show that for donors of similar molecular volume the binding energy of molecular complex increases with polarizability of donor molecules. Similarly, for such complexes the partial charges on molecules increase with decreasing of ionization potentials of donor molecules. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Mass spectrometric determination of the dissociation energy of Mn2F6(g)
Authors: Ciccioli Andrea , Rau Julietta V. , Balducci Giovanni , Brutti Sergio , Chilingarov Norbert N. , Gigli Guido , Cesaro Stella Nunziante
Published: October 2002

The gaseous Mn2F6 molecule has been identified for the first time in the vapor produced by MnF3 vaporization and the MnF3(g) dimerization equilibrium studied by the Knudsen cell mass spectrometry technique in the 884–1015 K temperature range. The experimental vapor pressure data were treated by the second‐ and third‐law procedures, and the enthalpy of Mn2F6(g) dissociation has been determined as: $\font\mathbfit=cmmib10\def\bfit#1{\hbox{\mathbfit #1}} {\bf \Delta {\bfit H}_{0}^{o} [Mn_{2}F_{6}(g)] = 210.9 \pm 2.5 kJ/mol}$. Thermodynamic functions of gaseous MnF3 were calculated from geometrical and vibrational parameters taken from the literature. For gaseous Mn2F6, they were evaluated by comparison with molecular parameters of Co2F6(g). Copyright © 2002 John Wiley & Sons, Ltd.
A combined ion source for fast switching between electrospray and matrix‐assisted laser desorption/ionization in Fourier transform ion cyclotron resonance mass spectrometry
Authors: Baykut Gökhan , Fuchser Jens , Witt Matthias , Weiss Gerhard , Gosteli Christoph
Published: October 2002

A new ion source has been developed for Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) that enables quick changes between matrix‐assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) modes. When operating as an ESI source, the sample solution is sprayed through an angled nebulizer. The generated ions pass through a glass capillary followed by a skimmer and three sequential hexapole ion guides. Ions can be accumulated in the third hexapole (storage hexapole) before they are injected into the ICR trap. The second hexapole is mounted on a movable platform which also carries the MALDI sample plate. During the switch from ESI to MALDI, this platform moves the second hexapole out of the hexapole series and locates a MALDI sample plate with 384 sample positions into the area directly in front of the storage hexapole. The storage hexapole is in a medium pressure chamber (MPC) which has windows both for the incoming laser beam and for the observation optics, as well as a gas tube for pulsing collision gas into the chamber. During the MALDI operation the focused laser beam enters the MPC, passes between the hexapole rods and irradiates a MALDI sample on the target plate. The sample molecules are desorbed/ionized into the storage hexapole and simultaneously cooled by collisions with the pulsed gas. Ions desorbed from multiple laser shots can be accumulated in this hexapole before they are transferred to the ICR trap. With the combined ion source a computer‐controlled switch between MALDI and ESI modes is possible in less than a minute, depending on the position of the MALDI target on the 384‐spot plate. Immediate acquisition of mass spectra is possible after mode switching without the need for tuning or re‐calibration. Copyright © 2002 John Wiley & Sons, Ltd.
New results on matrix‐assisted laser desorption/ionization mass spectrometry of widely polydisperse hydrosoluble polymers
Authors: Malvagna Paola , Impallomeni Giuseppe , Cozzolino Rosaria , Spina Emanuela , Garozzo Domenico
Published: October 2002

Polyvinylpyrrolidone (PVP) of molecular weight (Mw) 40 000 and 160 000 and polydispersity of 1.8–2.2 was shown to yield matrix‐assisted laser desorption/ionization (MALDI) mass spectra with the correct molar mass distribution of the polymer. This is a unique behavior among widely polydisperse samples and was ascribed to the capacity of PVP to complex the MALDI matrix. This result prompted us to test a new sample preparation technique consisting of flash‐freezing followed by freeze‐drying of the solution of the polymer with the matrix. In this paper we describe our preliminary results on MALDI‐MS of polydisperse polymers obtained by this technique. This sample preparation method allowed us to obtain, for the first time, spectra yielding the true molecular weight distribution of polydisperse samples such as dextran, lichenan, nigeran, and poly(ethylene oxide). Copyright © 2002 John Wiley & Sons, Ltd.
Some properties of ion trajectories in the radial plane of an axially symmetric ion trap
Authors: Sheretov Ernst P. , Philippov Igor V. , Karnav Tatiana B. , Ivanov Vladimir W.
Published: October 2002

In this article we analyse the trajectories of externally generated ions injected in the radial plane into the ion trap. The shape of the envelope curves for two‐dimensional (2D) ion trajectories is determined. Conditions under which these envelope curves can be transformed into circles are found. We show that the amplitude of ion oscillations is a minimum in this case and that this mode corresponds to optimised ion trapping conditions. Also we discuss a ring‐shaped ion trap mass spectrometer electrode system which consists of two ring electrodes, and which utilises ion trajectories with circular envelope curves. Copyright © 2002 John Wiley & Sons, Ltd.
Automatic sleep stage scoring based on waveform recognition method and decision‐tree learning
Authors: Hanaoka Masaaki , Kobayashi Masaki , Yamazaki Haruaki
Published: October 2002

There have been many trials in which the waveform recognition method, which is intended to replace expert observation by computer processing, has been used to extract the features of biological signals during sleep, and to automatically score sleep stages based on feature parameters. This paper proposes a waveform recognition method which extracts the feature parameters based on the characteristics of the biological signal during sleep, and a method of automatic sleep stage scoring by decision‐tree learning, which is currently considered to be one of the most successful machine learning methods in practice. As the first step in the method, the features corresponding to the state of the EEG, the EOG, and the EMG during sleep are compared to the features of characteristic waves such as the α‐wave, δ‐wave, sleep spindle, K‐complex, and REM, and the feature parameters needed in order to judge the sleep stage are extracted. Using canonical discriminant analysis and discretization method RWS based on the random walk, the feature parameters are converted to a small number of discrete variables. Based on training instances, obtained by the bootstrap method, a set of multiple small decision trees (a committee) is formed, and the sleep stage is scored by majority decision in the classification results. The method is applied to the PSG chart digital data provided by the Japan Sleep Society, and the performance of the system is evaluated experimentally. It is verified that the proposed method is promising as a method of automatic sleep stage scoring with high accuracy, requiring little expenditure of time in learning and classification. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(11): 1–13, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10248
Reflectometry studies of the oxidation kinetics of thin copper films
Authors: Njeh Anouar , Wieder Thomas , Fuess Hartmut
Published: October 2002

Oxide formation on magnetron‐sputtered thin copper films (35 nm thickness) was studied by x‐ray reflectometry and grazing incidence x‐ray diffraction. The films were oxidized in air at temperatures of 175° C, 200° C, 225° C and 250° C. The reflectometry and the diffractometry data indicate the formation of Cu2O. A power‐law dependence of the oxide layer thickness was found. The activation energy obtained is weakly time dependent. Copyright © 2002 John Wiley & Sons, Ltd.
How to develop and to reuse the UniPDM framework
Authors: Kim Jeong Ah
Published: October 2002

Reuse through frameworks promises improved productivity and reduced learning curves across the enterprise. Although many enterprise framework projects have commenced, few real enterprise frameworks have achieved noteworthy success. Our research with enterprise frameworks focuses on product data management. In this paper we focus on the current state and the findings of our project. Through our efforts we believe we have identified some important lessons for teams involved in enterprise framework development. Our discussion will concentrate on the following: (1) the phases of developing our framework; (2) applying the design pattern; (3) supporting environments for customizing the framework; (4) the problems in developing a framework. Copyright © 2002 John Wiley & Sons, Ltd.
Enterprise frameworks for workflow management systems
Authors: Gimenes Itana M. S. , Barroca Leonor
Published: October 2002

This paper proposes an enterprise framework for workflow management (WFM) systems based on the Workflow Management Coalition generic architecture. In addition, it presents one smaller object‐oriented framework for task scheduling. This framework is obtained by refining one of the packages of the overall framework. The task scheduling framework was designed following the concept of model framework as in Catalysis. This sort of framework can be used as a template to generate code components within an application domain. According to this approach we can develop WFM components that can interoperate within a well‐defined enterprise framework. This paper also presents the process of developing interoperable code components from model frameworks. Copyright © 2002 John Wiley & Sons, Ltd.
Using execution trace data to improve distributed systems
Authors: Moe Johan , Carr David A.
Published: October 2002

One of the most challenging problems facing today's software engineer is to understand and modify distributed systems. One reason is that in actual use systems frequently behave differently than the developer intended. In order to cope with this challenge, we have developed a three‐step method to study the run‐time behavior of a distributed system. First, remote procedure calls are traced using CORBA interceptors. Next, the trace data is parsed to construct RPC call‐return sequences, and summary statistics are generated. Finally, a visualization tool is used to study the statistics and look for anomalous behavior. We have been using this method on a large distributed system (more than 500000 lines of code) with data collected during both system testing and operation at a customer's site. Despite the fact that the distributed system had been in operation for over three years, the method has uncovered system configuration and efficiency problems. Using these discoveries, the system support group has been able to improve product performance and their own product maintenance procedures. Copyright © 2002 John Wiley & Sons, Ltd.
Life planning: Preparing for transitions and retirement
Authors: Nuss Elizabeth , Schroeder Charles
Published: October 2002

Long‐range career planning is difficult in the student affairs profession because of the lack of clearly defined career tracks and inherent job insecurities. The authors present and discuss strategies for planning for retirement and other late career options.
Effect of SA4503 on the electrically evoked release of 3H‐acetylcholine from striatal and hippocampal rat brain slices
Authors: Horan Bryan , Gifford Andrew N. , Matsuno Kiyoshi , Mita Shiro , Ashby Charles R.
Published: October 2002

Recent microdialysis data has shown that the systemic administration of the selective σ1 receptor agonist SA4503 increases the extracellular levels of acetylcholine (ACh) in the hippocampus, but not the striatum, of freely moving rats. In the present study, we examined the effect of SA4503 on the electrically evoked release of 3H‐ACh in rat brain slices isolated from the hippocampus and striatum. At 100 and 300 nM concentrations of SA4503, the electrically evoked release of 3H‐ACh was increased in hippocampal but not striatal slices. Concentrations below 100 nM did not alter the electrically evoked release of 3H‐ACh in either brain area. These results tentatively suggest that the increase in extracellular ACh levels observed in the hippocampus after the systemic administration of SA4503 could in part be related to its interaction with σ1 receptors in the hippocampus. Synapse 46:1–3, 2002. © 2002 Wiley‐Liss, Inc.
Teacher communication behavior and its association with students' cognitive and attitudinal outcomes in science in Taiwan
Authors: She Hsiao‐Ching , Fisher Darrell
Published: October 2002

In the study described in this article a questionnaire was employed that can be used to assess students' and teachers' perceptions of science teachers' interpersonal communication behaviors in their classroom learning environments. The Teacher Communication Behavior Questionnaire (TCBQ) has five scales: Challenging, Encouragement and Praise, Non‐Verbal Support, Understanding and Friendly, and Controlling. The TCBQ was used with a large sample of secondary science students in Taiwan, which provided additional validation data for the TCBQ for use in Taiwan and cross‐validation data for its use in English‐speaking countries. Girls perceived their teachers as more understanding and friendly than did boys, and teachers in biological science classrooms exhibited more favorable behavior toward their students than did those in physical science classrooms. Differences were also noted between the perceptions of the students and their teachers. Positive relationships were found between students' perceptions of their teachers' communication behaviors and their attitudes toward science. Students' cognitive achievement scores were higher when students perceived their teacher as using more challenging questions, as giving more nonverbal support, and as being more understanding and friendly. The development of both teacher and student versions of the TCBQ enhances the possibility of the use of the instrument by teachers. © 2002 John Wiley & Sons, Inc. J Res Sci Teach 39: 63–78, 2002
Developing effective intercultural relationships: The importance of communication strategies
Authors: Harvey Michael G. , Griffith David A.
Published: October 2002

As global competition intensifies, it is becoming necessary for organizations to establish strong intercultural

relationships with a culturally diverse set of employees, interorganizational partners as well as customers. In

order to manage these relationships effectively, organizations need a means to understand and improve global

intercultural communications. The complexity of intercultural communications requires management to understand the

nature of domains of global relationships and the level of complexity when attempting to communicate with multiple

partners having unique national and organizational cultures. In this article, a decision process for developing

effective intercultural communication strategies is developed, illustrating the steps necessary for managing a

myriad of intercultural relationships. © 2002 Wiley Periodicals, Inc.
Toxicity assessment of cyanobacterial toxin mixtures
Authors: Wolf Hans Uwe , Frank Christian
Published: October 2002

A method is presented for the toxicity assessment of mixtures of cyanobacterial toxins with hepatotoxic, neurotoxic, and carcinogenic effects. The method is based on the derivation of toxicity equivalent factors obtained from toxicological data presented for cyanobacterial toxins in the literature and on the use of toxicity equivalents in analogy with the method used for polychlorinated dibenzo[p]dioxins and dibenzofurans. Because the method easily can include all toxicological data for cyanobacterial toxins at any time, the quality of the toxicity assessment of these toxins can be increased continuously depending on data availability. Generally, all toxicologically relevant cyanobacterial toxins for which data are available should be included in this assessment. The method is considered useful in the toxicity assessment of cyanobacterial toxin mixtures in surface water bodies and in drinking water. When using the total sum of the toxicity equivalents, the approach proposed here seems to lead to a more realistic toxicity assessment of cyanobacterial toxin mixtures than does the worst‐case approach. However, the availability of data about acute and, especially, chronic toxicity must be increased significantly in the future in order to establish toxicologically validated exposure limit values for cyanobacterial toxins, especially those with hepatotoxic, neurotoxic, and carcinogenic effects. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 395–399, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10066
Examination of compound formation at interface of tin–bismuth–silver solder and copper substrate by using electron probe micro analysis
Authors: Tanabe T. , Harada S.
Published: October 2002

The wettability of tin–bismuth–silver solders on copper was studied by using energy‐dispersive x‐ray spectrometry (EDXRS) for elemental analysis. Four kinds of fluxes were used. The wettability of conventional eutectic tin–lead solder was much higher than that of solders based on tin–bismuth systems. The poor wettability of tin–bismuth solders may be caused by the growth of dendritic copper–tin compounds at the copper/solder interface, in contrast to the case of tin–lead solder. The wettability was improved by addition of silver to the solder. In the tin–bismuth–silver system, EDXRS mapping of elements revealed that silver was abnormally concentrated at the copper/solder interface even in the initial stage of their contact. When using FR‐type fluxes, the solder exhibited maximum wettability in the range from 1–4 mass% Ag addition. The layer thickness of the Cu–Sn compound formed on Cu was smallest with a 2% Ag addition. This may correspond to the improvement of the solder wettability. Copyright © 2002 John Wiley & Sons, Ltd.
Fiber digestibility and nitrogen requirements of blue duikers (Cephalophus monticola)
Authors: Shipley Lisa A. , Felicetti Laura
Published: October 2002

We examined the energy and protein requirements, and the fiber and protein digestive capacity, of a small African ruminant, the blue duiker (Cephalophus monticola), by conducting a series of complete balance digestion trials with three captive male blue duikers feeding on fruits, leaves, forbs, grass, and pelleted diets ranging from 9.4% to 49% neutral detergent fiber (NDF), and 2.5% to 30% crude protein. The diets also varied in tannin levels. On these diets, for which indigestible acid detergent lignin (ADL) comprised 5–20% of NDF, blue duikers digested NDF as well as did larger ruminants. With a metabolic fecal nitrogen (MFN) of 2.6 g N/kg dry matter consumed and endogenous urinary N (EUN) of 194 mg/kg0.75/d, the duikers required 643.3 mg N/kg0.75/d. Therefore, if food intake is unrestricted, duikers require a minimum protein content in their diet of about 4%. MFN and N requirements were lower than those of many other ruminants. The protein‐precipitating capacity of tannins found in forages used in this study did not reduce the digestibility of the neutral detergent solubles (NDS) and NDF, but significantly reduced protein digestion. However, this reduction appears to be less than that experienced by larger ruminants. Small ruminants, such as the blue duiker, seem to be able to handle lower‐quality diets than expected for their size. Zoo Biol 21:123–134, 2002. © 2002 Wiley‐Liss, Inc.
Hemolytic function of opsonizing proteins of earthworm's coelomic fluid
Authors: Šinkora Marek , Bilej Martin , Tučková Ludmila , Romanovský Alexej
Published: October 2002

Synthetic 2‐hydroxyethylmethacrylate copolymer particles (HEMA) can be opsonized in the coelomic fluid of Eisenia foetida earthworms. The incomplete coelomic fluid (i.e. the coelomic fluid after incubation with HEMA particles) exerts a lower level of hemolytic activity compared to complete coelomic fluid. The decreased hemolysis can be compensated by the addition of isolated opsonins. On the other hand, isolated opsonins do not possess direct hemolytic capacity. It can be suggested that at least one of the isolated opsonins is involved in the hemolytic process. These results support the hypothesized cooperation of humoral and cellular mechanisms in earthworm defence.
Imaging calcium dynamics in living plant cells and tissues
Authors: Read N. D. , Shacklock P. S. , Knight M. R. , Trewavas A. J.
Published: October 2002

The central role of Ca2+ signalling in plants is now well established. Much of our recent research has been based on the premise that the direct demonstration of signal‐response coupling via Ca2+ requires the imaging or measurement of cytosolic free Ca2+ in living cells. Methods (confocal microscopy, fluorescence ratio imaging and photon counting imaging) which we use for imaging Ca2+ with fluorescent dyes or recombinant aequorin, are described. Approaches for using dyes are now routine for many plant cells. However, the imaging Ca2+ in whole tissues of plants genetically transformed with the aequorin gene is a very new development. We predict that this method, first employed in our laboratory, will bring about a revolution in our understanding of Ca2+ signalling at the multicellular level.
Multiple pathways to apoptosis.
Authors: Evans Vivian G.
Published: October 2002

Evidence from studies dealing with various aspects of the interdigitating network of proliferative signals supports the concept of multiple signalling pathways. Analogous to these, the concept of multiple pathways to apoptosis is introduced and discussed. Some of these pathways might not necessarily be under genetic control. They might be elicited by a perturbation at any point in the proliferative signalling network, for example by an imbalance in any of the substances involved directly or as second messengers. Diverse findings from recent reports on the induction of apoptosis by various means and in a variety of cell lines imply the presence of such multiple pathways, only one of which should accurately be described as genetic.