bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trimodal random‐field distribution of a mixed spin Ising model
Authors: Liang Ya‐Qiu , Wei Guo‐Zhu , Song Guo‐Li 
Published: June 2004

AbstractA mixed spin Ising system consisting of spin‐1/2 and spin‐3/2 with a random field is studied theoretically by the use of effective field theory with correlations (EFT). The phase diagrams and thermal behaviors of magnetization are investigated numerically for a square lattice (z = 4) when the random field is bimodally and trimodally distributed. The results show that tricritical points exist when the external random fields H and the values of p are not too large. Re‐entrant phenomena can be seen for appropriate ranges of p and random fields H. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extending Wertheim's perturbation theory to high‐density molecular solids
Authors: Singh V. K. , Khanna K. N. 
Published: June 2004

AbstractWe report a theoretical study of a two‐dimensional hard homonuclear dumbbell‐shaped molecular system with a high anisotropy parameter d* = 0.924 employing Wertheim's first‐order perturbation theory. The thermodynamic state of the molecular solid known as HB‐crystalline phase is discussed. The equation of state, free energy and fluid‐solid phase transition are reported. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The ferro–paraelectric phase transition of Pb0.6Ba0.4Nb2O6 investigated by Raman scattering
Authors: Lima‐Silva J. J. , Garcia D. , Mendes Filho J. , Eiras J. A. , Ayala A. P. 
Published: June 2004

AbstractThe temperature dependence of the vibrational modes of lead barium niobate (PbxBa1–xNb2O6), which belongs to the tungsten‐bronze family of oxygen octahedra ferroelectrics, were investigated for the first time using the Raman scattering technique. The investigated sample (x = 0.60) exhibits a ferro–paraelectric phase transition in the measured temperature range. Clear evidence of the structural transformation was observed in the temperature dependence of the phonon energy as well as in the linewidth and the integrated intensity of the Raman bands. The Raman bands assignment was discussed in terms of the vibrational modes of the oxygen octahedron. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface passivation in CdSe nanocrystal–polymer films revealed by ultrafast excitation relaxation dynamics
Authors: Kovalevskij V. , Gulbinas V. , Piskarskas A. , Hines M. A. , Scholes G. D. 
Published: June 2004

AbstractThe photoluminescence efficiencies and excitation relaxation dynamics in CdSe nanocrystals (NC) passivated with tri‐n‐octylphosphine oxide and embedded in two different polymer matrixes, poly(styrene) (PS) and poly(butylmethacrylate) (PBMA), are compared. Femtosecond pump‐probe absorption spectroscopy is used to clarify the influence of various transparent polymer matrixes on the electronic properties and excitation relaxation dynamics of quantum confined CdSe semiconductor nanocrystals of 5.0 nm diameter. The fluorescence intensity is reported to be ∼10 times higher for the NC‐PS sample compared to the NC‐PBMA film. This striking difference in fluorescence yield is shown to be related to markedly different rates of nonradiative excitation relaxation in the two samples, and is attributed directly to a role played by the polymer host. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modified two‐sided normal tolerance intervals for batch acceptance of dose uniformity
Authors: Hauck Walter W. , Shaikh Reshama 
Published: June 2004

AbstractWe consider modified tolerance intervals for assessing content (dose) uniformity from one‐ and two‐stage designs. This work was motivated by a proposal from the International Pharmaceutical Aerosol Consortium on Regulation and Science (IPAC‐RS) to modify tolerance intervals to reduce their known conservatism away from the centre of the acceptance interval. IPAC‐RS's original proposal suffers from anti‐conservatism, but we find this is due to the choice of constants, not the form of the acceptance rule. We propose an alternative basis for choosing the constants in the acceptance rules and compare attained levels to those of other choices, including revised constants proposed by IPAC‐RS. These alternate choices of the constants lead to modified tolerance intervals that are either conservative at the sample sizes for which they were chosen or may have slight anti‐conservatism, within the limits of the simulations. Copyright © 2004 John Wiley & Sons, Ltd.
Carry‐over in cross‐over trials in bioequivalence: theoretical concerns and empirical evidence
Authors: Senn Stephen , D'Angelo Giuseppina , Potvin Diane 
Published: June 2004

AbstractThere is now general agreement that pre‐testing for carry‐over in the AB/BA design is harmful and that efficient analysis of this design must proceed on the assumption that carry‐over has not affected the results to any appreciable degree. A general consensus has not been achieved in the case of higher‐order designs. Since particular forms of carry‐over can be estimated on a within‐patient basis and unbiased within‐patient treatment estimators are possible, some statisticians favour pre‐testing and some favour automatic adjustment for carry‐over. We present theoretical arguments that show that, just as in the AB/BA case, the strategy of pre‐testing is biased as a whole and also that the loss in terms of efficiency in adjusting is not negligible. We also present data from two large series of bioequivalence studies to provide empirical evidence that in this context carry‐over is either absent or rare. We conclude that adjusting or testing for carry‐over in bioequivalence studies is at worst harmful and at best pointless, and that this may also apply to other kinds of study. Copyright © 2004 John Wiley & Sons, Ltd.
The influence of orientation and strength of external magnetic field on the time dependences of populations of atomic levels for Lamda systems
Authors: Karagodova Tamara Ya. 
Published: June 2004

AbstractThe theory of interaction of intense laser fields with multilevel atoms in external constant magnetic fields is applied to analysis of the dependences of the populations on time, on detuning of laser frequency, on magnetic field orientation, and strength for spontaneous decay on the levels of thermostat. Solving the Schrödinger equation for the “atom in magnetic field + radiation field” system in resonant approximation we have obtained the probability of the population of common level for a generalized Λ system (e.g., 6P1/2‐7S1/2‐6P3/2 levels of Tl atoms). The results of computer simulations permit the investigation of the peculiarities of coherent population trapping in such system. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Nature of O2, CO, and CN binding to hemoprotein models
Authors: Torrens F. 
Published: June 2004

AbstractParametrization of a molecular‐mechanics program to include terms specific for five‐ and six‐coordinate transition metal complexes results in computer‐simulated structures of hemo complexes. The principal new feature peculiar to five‐ and six‐coordination is a term that measures the effect of electron‐pair repulsion modified by the ligand electronegativity and takes into account the different structural possibilities. The work consists in the modification of program molecular mechanics for penta and hexacoordination. The model system takes into account the structural differences of the fixing center in the hemoglobin subunits. The customary proximal histidine is added. The macrocycle hemo IX is wholly considered in our model. The calculations show clearly that certain conformations are much more favorable that others for fixing O2. From the O2 binding in hemoglobin and myoglobin and in simple Fe porphyrin models, it is concluded that the bent O2 ligand is best viewed as bound superoxide, O. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Electrospray ionization mass spectrometric characterization and quantitation of xanthine derivatives using isotopically labelled analogues: an application for equine doping control analysis
Authors: Thevis Mario , Opfermann Georg , Krug Oliver , Schänzer Wilhelm 
Published: June 2004

AbstractIsotope‐dilution mass spectrometry has been employed successfully in numerous fields of analytical chemistry enabling the establishment of fast and reliable procedures. In equine sports, xanthine derivatives such as caffeine and theobromine are prohibited, and doping control laboratories analyze horse urine specimens regarding these illicit performance‐enhancing drugs. Theobromine has to exceed a threshold level of 2 μg/mL, hence a robust and reliable quantitation is required. Stably deuterated theobromine and caffeine were synthesized by the reaction of xanthine or theobromine with iodomethane‐d3 in the presence of N‐methyl‐N‐trimethylsilyltrifluoroacetamide or potassium carbonate in acetonitrile, respectively. Both compounds were characterized by nuclear magnetic resonance spectroscopy and electrospray ionization tandem mass spectrometry, and a robust and fast assay for the qualitative and quantitative analysis of theobromine in equine urine samples was validated. Urine specimens were extracted by means of solid‐phase extraction cartridges, and concentrated extracts were analyzed by liquid chromatography interfaced to a triple‐quadrupole mass spectrometer. In addition, the dissociation behavior of deuterated analogues to caffeine and theobromine allowed proposals for fragmentation routes of xanthine derivatives after atmospheric pressure ionization and collisionally activated dissociation. Copyright © 2004 John Wiley & Sons, Ltd.
Influence of flooding on δ15N, δ18O,1δ15N and2δ15N signatures of N2O released from estuarine soils—a laboratory experiment using tidal flooding chambers
Authors: Bol R. , Röckmann T. , Blackwell M. , Yamulki S. 
Published: June 2004

AbstractThe influence of flooding on N2O fluxes, denitrification rates, dual isotope (δ18O andδ15N) and isotopomer (1δ15N and2δ15N) ratios of emitted N2O from estuarine intertidal zones was examined in a laboratory study using tidal flooding incubation chambers. Five replicate soil cores were collected from two differently managed intertidal zones in the estuary of the River Torridge (North Devon, UK): (1) a natural salt marsh fringing the estuary, and (2) a managed retreat site, previous agricultural land to which flooding was restored in summer 2001. Gas samples from the incubated soil cores were collected from the tidal chamber headspaces over a range of flooding conditions, and analysed for theδ18O,δ15N,1δ15N and2δ15N values of the emitted N2O. Isotope signals did not differ between the two sites, and nitrate addition to the flooding water did not change the isotopic content of emitted N2O. Under non‐flooded conditions, the isotopic composition of the emitted N2O displayed a moderate variability inδ18O and2δ15N delta values that was expected for microbial activity associated with denitrification. However, under flooded conditions, half of the samples showed strong and simultaneous depletions in1δ15N andδ18O values, but not in2δ15N. Such an isotope signal has not been reported in the literature, and it could point towards an unidentified N2O production pathway. Its signature differed from denitrification, which was generally the N2O production pathway in the salt marsh and the managed retreat site. Copyright © 2004 John Wiley & Sons, Ltd.
Mass spectrometric analysis of ceramide perturbations in brain and fibroblasts of mice and human patients with peroxisomal disorders
Authors: Pettus Benjamin J. , Baes Myriam , Busman Mark , Hannun Yusuf A. , Van Veldhoven Paul P. 
Published: June 2004

AbstractIn this study, the levels and composition of ceramides in brains of newborn mice lacking peroxisomes (Pex5−/−, Zellweger mice) were analyzed using normal‐phase high‐performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI‐MS). Total ceramide compositions were found to be comparable to that of control animals. However, a minor ceramide species, containing hexacosanoic/hexacosenoic acid as the amide fatty acid, was 9‐fold increased. Also, in the sphingomyelin‐derived ceramides this species was elevated. Subsequent analysis of extracts from fibroblasts of Pex5−/− mice and mice with a defective peroxisomal β‐oxidation (lacking D‐specific multifunctional protein 2 (MFP2)), revealed, again, a similar rise in this particular ceramide. Further, this ceramide was elevated in human X‐ALD fibroblasts as well. Whether C26:1/0‐ceramide is linked to some of the pathology seen in Zellweger syndrome remains to be investigated. However, an increase in this sphingolipid can be considered as a diagnostic criterion for diseases caused by defects in peroxisome biogenesis or peroxisomal β‐oxidation. Copyright © 2004 John Wiley & Sons, Ltd.
Identification of variant forms of the neuroendocrine peptide galanin
Authors: Norberg Åke , Griffiths William J. , Hjelmqvist Lars , Jörnvall Hans , Rökaeus Åke 
Published: June 2004

AbstractGalanin is a neuroendocrine peptide widely distributed in the central and peripheral nervous systems and in endocrine tissues. Using radioimmunoassays, chromatographic separations, and tandem mass spectrometry, we have identified a series of five variant forms of galanin purified from porcine upper intestine. The modified variants include three β‐aspartyl‐shifted forms, an oxidized form containing Trp monooxide, and an N‐terminally truncated form. All were found to be C‐terminally amidated. At least the β‐aspartyl‐shifted forms could be of native occurrence. Mechanistic explanations of the mass spectrometric fragmentation patterns of the different forms are suggested. Copyright © 2004 John Wiley & Sons, Ltd.
Validation of a real‐time monitoring method for aniline in freshwater by high‐performance liquid chromatography on porous graphitic carbon/electrospray ionization tandem mass spectrometry
Authors: Delépée Raphaël , Chaimbault Patrick , Antignac Jean‐Philippe , Lafosse Michel 
Published: June 2004

AbstractAniline is an anthropogenic organic compound widely used in polymer, rubber, pharmaceutical and dye industries but also used in biodegradability assays of chemical compounds as a positive biodegradation standard. By the two approaches, the rapid determination of aniline is necessary because of the high toxicity of aniline on hemoglobin. A high‐performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method for the determination of aniline in water is described here. This method, using benzylamine as internal standard, was validated. No time‐consuming sample preparation was needed. A rapid separation (7 min between two chromatographic runs) of aniline and benzylamine was performed on a Hypercarb porous graphitic carbon column using a gradient of methanol and 100 mM formic acid. The obtained limits of detection and quantification were 10 and 1 ng/mL, respectively. The response for aniline was quadratic. We show that this problem could be circumvented by showing that the [calculated concentration = f(introduced concentration)] function was linear. The linearity range was 10–1000 ng/mL. An example of an application consisting of an aniline 42‐day degradation kinetic in water was demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
Correlations between air levels of hexahydrophthalic anhydride (HHPA) and HHPA‐adducted albumin tryptic peptides in nasal lavage fluid from experimentally exposed volunteers
Authors: Kristiansson Monica H. , Lindh Christian H. , Jönsson Bo A. G. 
Published: June 2004

AbstractOrganic acid anhydrides (OAAs) are low molecular weight, reactive compounds extensively used in industry. Exposure to these compounds may lead to allergic symptoms such as rhinitis and asthma. It is important to develop better and more informative methods for assessment of exposure to OAAs. The aim of this study was to develop a method for analysis of specific hexahydrophthalic anhydride (HHPA)‐adducted tryptic peptides of human serum albumin (HSA) in nasal lavage (NAL). Furthermore, these peptides were evaluated as biomarkers of exposure. The proteins in the NAL samples were reduced, alkylated and digested with trypsin and the obtained peptides were analyzed using liquid chromatography/tandem mass spectrometry. The total amount of hydrolyzable HHPA in an HHPA‐HSA conjugate was used for calibration. A deuterium‐labeled HHPA‐HSA conjugate was used as internal standard. Five volunteers were exposed to 10, 40 and 80 μg/m3 of HHPA in an exposure chamber and NAL samples were collected before and after exposure. Acceptable precisions of the assay at 13–14% were found for three adducted peptides. The mean levels of these three peptides for the five subjects ranged between 5–22, 15–75 and 33–125 pmol/mL NAL for the exposures at 10, 40 and 80 μg/m3, respectively. High correlations between air levels and the measured peptides were found on an individual basis but there were large inter‐individual differences ranging between 63 and 110% for the three peptides. The large differences remained after protein adjustments. It was possible to detect exposures below 10 μg/m3 with the method. Thus, these adducted peptides may be used as biomarkers of exposure, which may better estimate the risk than previous biomarkers developed for OAAs. Copyright © 2004 John Wiley & Sons, Ltd.
Flexible XML‐based configuration of physical simulations
Authors: Sunderland R. M. , Damper R. I. , Crowder R. M. 
Published: June 2004

AbstractThe extensible markup language XML can be used to support the integration of several component programming environments to create a flexible physical simulation system. Data exchange via open‐standard‐based plain text files allows system components to be loosely‐coupled, rather than combined into an integrated development environment, so that the most appropriate tools can be used for each component and the system can be extended with minimal disruption. This paper details an example application using this technology to configure a simulation of robotic manipulation. Those parts of the system that require real‐time data exchange use simple UNIX socket‐based interactions, which are configured using shared XML setup files. The approach provides a reusable template for other, similar projects. Copyright © 2004 John Wiley & Sons, Ltd.
Object‐oriented processing of Java source code
Authors: Eichelberger Holger , Wolff von Gudenberg Jürgen 
Published: June 2004

AbstractCode transformation and analysis tools provide support for software engineering tasks such as style checking, testing, calculating software metrics as well as reverse‐ and re‐engineering. In this paper we describe the architecture and the applications of JTransform, a general Java source code processing and transformation framework. It consists of a Java parser generating a configurable parse tree and various visitors (transformers, tree evaluators) which produce different kinds of outputs. While our framework is written in Java, the paper further opens an opportunity for a new generation of XML‐based source code tools. Copyright © 2004 John Wiley & Sons, Ltd.
Eight maxims for software inspectors
Authors: Kelly Diane , Shepard Terry 
Published: June 2004

AbstractSoftware inspections are an intensely people‐centric activity. Even though this is routinely recognized in industry, much of the research focuses on inspection mechanics. During three years of inspection experiments, even though the main purpose of the experiments was to investigate the effectiveness of a particular technique, the inspectors involved provided broad comments on many other aspects of inspections. Their comments were collected and organized into themes. These themes are presented here as a set of maxims that cover all the topics that the inspectors felt were important as they endeavoured to do good inspections. Copyright © 2004 John Wiley & Sons, Ltd.
Anion Controlled Supramolecular Self‐Assembly of Tetraprotonated Tris[2‐(benzylamino)ethyl]amine
Authors: Antonioli Bianca , Gloe Kerstin , Gloe Karsten , Goretzki Gudrun , Grotjahn Manuela , Heßke Holger , Langer Matthias , Lindoy Leonard F. , Mills Allison M. , Söhnel Tilo 
Published: June 2004

AbstractThe novel supramolecular assembly of composition [{(bz3tren)H4}4+ · (ReO4)— · 3(Cl)—] resulted from the self‐organization of a mixture of tris[2‐(benzylamino)ethyl]amine (bz3tren), HCl and NH4ReO4 at a molar ratio of 1:4.7:1 in methanol. The crystal architecture is characterized by stacks of repeating sandwich‐type building blocks that contain charge‐assisted N—H···O(Re) hydrogen bonds [N···O 2.81‐2.86Å] and weaker C—H···O(Re) interactions [C···O 3.11Å]. The stacks are further linked by N—H···Cl [N···Cl 3.03Å] and weaker C—H···Cl [C···Cl 3.47‐3.74Å] interactions into two‐dimensional layers bordered by the benzyl groups of the [(bz3tren)H4]4+ cations. Edge‐to‐face C—H···π interactions involving the aromatic rings occur within and between the layers. The protonation constants of bz3tren in methanol were determined by potentiometric titration. The corresponding structures of the ligand in its different protonation states were calculated at the DFT‐level.
Octafluor‐1, 2‐dimethylencyclobutan, ein perfluorierter Dien‐Komplexligand — Carbonyl(η5‐cyclopentadienyl)(η4‐octafluor‐1, 2‐dimethylencyclobutan)mangan
Authors: Lentz Dieter , Patzschke Mona 
Published: June 2004

AbstractOctafluoro‐1, 2‐dimethylenecyclobutane, a Perfluorinated Diene Ligand — Carbonyl(η5‐cyclopentadienyl)(η4‐octafluoro‐1, 2‐dimethylenecyclobutane)manganeseThe [2+2]‐cycloaddition product of tetrafluoroallene (1), octafluoro‐1, 2‐dimethylenecyclobutane (2) reacts with tricarbonyl(η5‐cyclopentadienyl)manganese (4) replacing two carbonyl ligands to give carbonyl(η5‐cyclopentadienyl)(η4‐octafluoro‐1, 2‐dimethylenecyclobutane)manganese (5). According to the IR spectrum of 5, the ligand 2 is a strong π acceptor. Among the less volatile by‐products of the dimerizationof 1, the hydrolysis product of its trimer could be structurally characterized by X‐ray diffraction as the spirocyclic compound decafluoro‐5‐methylene‐spiro[3.3]heptane‐2‐carboxylic acid (3). The structure of 5 was also determined by an X‐ray crystal structure determination.
Electron Beam Induced Transformation of MoO3 to MoO2 and a New Phase MoO
Authors: Wang D. , Su D. S. , Schlögl R. 
Published: June 2004

AbstractThe transformation of MoO3 induced by electron beam irradiation was studied by electron energy‐loss spectroscopy (EELS) in combination with electron diffraction and high‐resolution transmission electron microscopy (HRTEM) techniques. The routes of structure transformation were dependent on the applied electron current density. In case of low current density, MoO2 was obtained. In case of high current density, MoO with a rock‐salt structure is suggested to be the final phase. The change in oxidation states of the Mo oxides was deduced from the features in energy‐loss near edge structure (ELNES) of the O K‐edge. Quantitative analysis was successfully employed on Mo M3‐edge and O K‐edge to obtain the O/Mo ratio of the reduced phases. The mechanisms of different structure transformation behaviors were suggested in the frame of radiolysis enhanced diffusion.