bluuebunny/crossref_metadata_2025_split huggingface dataset:
Addition theorems as three‐dimensional Taylor expansions. II.Bfunctions and other exponentially decaying functions
Authors: Weniger Ernst Joachim 
Published: October 2002

AbstractAddition theorems can be constructed by doing three‐dimensional Taylor expansions according tof(r+r′)=exp (r′⋅∇)f(r). Since, however, one is normally interested in addition theorems of irreducible spherical tensors, the application of the translation operator in its Cartesian form exp (x′∂/∂x)exp (y′∂/∂y)exp (z′∂/∂z) would lead to enormous technical problems. A better alternative consists in using a series expansion for the translation operator exp (r′⋅∇) involving powers of the Laplacian ∇2and spherical tensor gradient operators\documentclass{article}\pagestyle{empty}\begin{document}$\mathcal{Y}^{m}_{\ell}(\nabla)$\end{document}, which are irreducible spherical tensors of ranks zero and ℓ, respectively (Santos, F. D. Nucl Phys A 1973, 212, 341). In this way, it is indeed possible to derive addition theorems by doing three‐dimensional Taylor expansions (Weniger, E. J. Int J Quantum Chem 2000, 76, 280). The application of the translation operator in its spherical form is particularly simple in the case ofBfunctions and leads to an addition theorem with a comparatively compact structure. Since other exponentially decaying functions like Slater‐type functions, bound‐state hydrogenic eigenfunctions, and other functions based on generalized Laguerre polynomials can be expressed by simple finite sums ofBfunctions, the addition theorems for these functions can be written down immediately. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Does digermane exhibit free rotation? A test of barrier theory
Authors: Goodman Lionel , Pophristic Vojislava , Wang Windy 
Published: October 2002

AbstractHartree–Fock/6‐311G(3df,2p) analysis of the digermane internal rotation barrier shows that at 300 K digermane is in large amplitude (∼40°) oscillation about the staggered equilibrium structure. Quantum superposition (hyperconjugation between the germanyl groups) is predicted to contribute less than half of the 0.8 kcal/mol barrier energy, but it is key to sufficiently rigidize the molecule to prevent free rotation. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Hermitian Fock matrix in the chemical Hamiltonian approach: Fulfilling Löwdin's prediction*
Authors: Mayer I. 
Published: October 2002

AbstractFollowing a remark of Löwdin, a technique is developed permitting one to formulate the BSSE‐fee SCF equations of the chemical Hamiltonian approach (CHA) by using a Hermitian Fock matrix. Contrary to the usual CHA practice, the energy is also calculated with the means of the same Fock matrix. This scheme reproduces exactly the CHA–SCF results usually obtained by using a non‐Hermitian Fock matrix for computing the orbitals and a conventional Hermitian one for computing the energy. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002
Methoxyphenols—antioxidant principles in food plants and spices: Pulse radiolysis, EPR spectroscopy, and density functional theory calculations*
Authors: Bors Wolf , Kazazic Snjezana P. , Michel Christa , Kortenska Vessela D. , Stettmaier Kurt , Klasinc Leo 
Published: October 2002

AbstractThe phenoxyl radicals of several phenols and phenolic acids with o‐methoxy groups were generated by pulse‐radiolytic oxidation with azide radicals and their buildup and decay evaluated with kinetic spectroscopy. Structures of the phenoxyl radicals were obtained with EPR spectroscopy and the experimental isotropic coupling constants confirmed by hybrid density‐functional calculations with Becke's three parameter hybrid functional using the Lee, Yang, and Parr functional theory and a variety of basis sets, and with consideration of the solvent. While the calculations resulted in reasonable correlations with the experimental data, the apparent distinction in the stability of the various radicals seems to be primarily due to kinetic rather than electronic effects. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Molecular dynamics study on liquid 1‐octanol. Part 2. Water‐saturated 1‐octanol solution*
Authors: Fernandes de Oliveira César Augusto , Guimarães Cristiano Ruch Werneck , Bicca de Alencastro Ricardo 
Published: October 2002

AbstractIn medicinal chemistry, partition coefficients are extremely important thermodynamic properties as they may be related to drug transfer across biological membranes. We are currently interested in obtaining octanol/water relative partition coefficients (Δlog Po/w) by using the free‐energy perturbation (FEP) technique within the Discover program (version 2.9.7) of MSI. In this program, however, FEP calculations can only be performed if the all‐atom consistent‐valence force field (CVFF) is used. As a consequence, we have recently derived new parameters for the 1‐octanol nonbonded terms of CVFF, which reproduce relevant physicochemical properties of its liquid state [Oliveira, C. A. F.; Guimarães, C. R. W.; Bicca de Alencastro, R. Int J Quantum Chem 2000, 80, 999–1006]. Nevertheless, the experimental measurements of the octanol/water partition coefficients are always conducted using 1‐octanol that has first been saturated with water. Therefore, in this work, we are verifying if the combination of the CVFF water model with the new CVFF parameters, derived for liquid 1‐octanol, describes the solvent mixture adequately. The good agreement observed between our calculated physicochemical properties, using molecular dynamics simulations, and experimental values and other theoretical results gives support to our model. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002
Reactivity of the NS2/3(907–1206)ASK4protein with β‐mercaptoethanol studied by electrospray ion trap mass spectrometry
Authors: Orsatti Laura , Pallaoro Michele , Steinküler Christian , Orru' Stefania , Bonelli Fabio 
Published: October 2002

AbstractThe present work reports a mass spectrometric investigation of the NS2/3 protein, a protease from hepatitis C virus (HCV). During routine protein manipulation, in the presence of 100 mM β‐mercaptoethanol and under denatured conditions, the protein was unexpectedly modified at its cysteine residues, and the increased molecular weight corresponded to one molecule of β‐mercaptoethanol bound. The modified protein, once refolded, was found to be less active than the unmodified one. The aim of this work was to investigate whether the reactivity of cysteines with β‐mercaptoethanol involves one specific, highly reactive residue of the sequence, or if the modification is a random process. Liquid chromatography (LC) coupled on‐line with an electrospray ion trap mass spectrometer was used to identify the modification sites. It was found that five cysteines out of nine had reacted with β‐mercaptoethanol, none of them showing a significantly higher reactivity than the others. 95% of sequence coverage was obtained. Copyright © 2002 John Wiley & Sons, Ltd.
ART in‐well air stripping—An innovative technology succeeds where other technologies have failed
Authors: Odah Mohamed 
Published: October 2002

AbstractAccelerated Remediation Technologies LLC (ART) developed a proprietary
(patent‐pending) effective remediation technology that is based on verified and established
concepts. The ART technology combines in‐situ air stripping, air sparging, soil vapor extraction, enhanced
bioremediation/oxidation, and Dynamic Subsurface CirculationTM in an innovative wellhead system.
The system is designed to accommodate a 4‐inch well and is cost‐effective when compared with other
remediation technologies. The air‐sparging component results in lifting the water table. This lifting of
the water in the well causes a net reduction in head at the well location. Vacuum pressure (the
vapor‐extraction component) is applied on top of the well point to extract vapor from the subsurface.
The negative pressure from the vacuum extraction results in water suction that creates additional water lifting
(mounding). A submersible pump is placed at the bottom of the well to recirculate water to the top for
downward discharge through a spray head. The water cascades down the interior of the well similar to what occurs
in an air‐stripping tower. Enhanced stripping via air sparging near the bottom of the well occurs
simultaneously. In essence, the well acts as a subsurface air‐stripping tower. The
pumped‐and‐stripped, highly oxygenated water flows down well annulus and over the
“mounded” water back in to the aquifer, which creates a circulation zone around the well to further
enhance cleanup.The ART technology has been implemented at several sites nationwide, including industrial laundry facilities,
manufacturing plants, and service stations, and has achieved significant reductions in contaminant
concentrations. Specifically, a concentration of tetrachloroethene (PCE) decreased from 2,700 to 240
μg/l, in 13 days. In less than three months, the concentrations dropped further to 79 μg/l, which
is within the range of background levels. Other sites utilizing the technology have exhibited similar reduction
trends in complex subsurface environments. © 2002 Wiley Periodicals, Inc.
High‐temperature‐aging‐promoted Rh oxides on supported automotive exhaust catalysts
Authors: Suhonen S. , Hietikko M. , Polvinen R. , Valden M. , Laitinen R. , Kallinen K. , Härkönen M. 
Published: October 2002

AbstractThermal decomposition of noble metal oxide phases formed during aging in air on industrially manufactured γ‐Al2O3‐supported Rh catalysts was investigated. Some of the catalyst washcoats were modified by various stabilizers, promoters and oxygen storage components, such as La2O3, CeO2 and Ce–Zr mixed oxide. In order to investigate the effect of aging, stabilizers and manufacturing method on the thermal stability of the noble metal oxide phases formed, a stepwise thermal decomposition in high vacuum (pressure <10−7 Torr) was performed. X‐ray photoelectron spectroscopy (XPS) was used to observe the changes in chemical state after each annealing cycle. Our results show marked differences in the rate of reduction between different Rh catalysts. Disposition of the Rh oxides towards reduction was also investigated by exposing the catalysts to 400 mbar of H2 at 300°C for 30 min. After 3 h of aging in air at 1000°C an irreducible rhodium oxide, which was identified to be either Rh2O3 diffused into alumina or RhO2 in intimate contact with the alumina surface, was formed regardless of the Ce–Zr mixed‐oxide additive and manufacturing method of the catalyst. Copyright © 2002 John Wiley & Sons, Ltd.
Environmental application of surface reactivity analysis
Authors: Lamari Darkrim F. , Levesque D. 
Published: October 2002

AbstractIn order to use hydrogen gas as an energy vector, several possibilities are under investigation and any new systems of gas storage should be secure, light, efficient and not expensive. Three technologies involving hydrogen gas energy have already been proposed: gas liquefaction at low temperature, gas compression at high pressure and the formation of metallic hydrides. Another technology corresponding to a variant of gas compression concerns gas adsorption under pressure.Considerable activity has been devoted to the experimental and numerical studies of nanoscale‐dimension material adsorptive properties in order to store hydrogen gas by adsorption. Thus, within the framework of studying hydrogen storage for future clean vehicles, we performed hydrogen adsorption on both current active carbons and promising new adsorbents. We carried out analysis of the gas/solid interface reactivity by numerical simulations. More specifically, we studied the potential of hydrogen adsorption by new graphitic materials, for which recent works have demonstrated that these adsorbents may have high adsorptive capacities owing to their surface reactivity in relation to their nanometric dimensions. These adsorbents present structures that are favourable to the adsorption phenomenon because of the attractive interaction range between gas molecules and adsorbent atoms. In this work, we studied the gas/solid interface reactivity in order to discuss the potential influence of carbon nanofibre dimensions on hydrogen adsorption. We performed Monte‐Carlo numerical simulations of gas adsorption on materials that could represent these adsorbents in reality. We computed these simulations in order to analyse interface reactivity and to obtain interface information and predictions of gas adsorption, with the aim of optimizing adsorbent structures for hydrogen adsorption. Moreover, we realized experimental studies of gas adsorption in microporous material in order to validate our numerical predictions and to obtain other information on the reactivity of the gas/solid interface. Copyright © 2002 John Wiley & Sons, Ltd.
Structure and composition of electrochemically prepared oxide layers on Co in alkaline solutions studied by XPS
Authors: Foelske Annette , Strehblow Hans‐Henning 
Published: October 2002

AbstractPassive layers on cobalt were prepared in 0.1 N NaOH (pH 13) under potentiostatic control with systematic variation of the relevant parameters, such as time and potential, and examined by x‐ray photoelectron spectroscopy (XPS). The electrochemical preparation of the sputter‐cleaned samples and their transfer to the ultrahigh vacuum was performed in a closed system under protection of purified argon. Evaluation of the XPS signals occurs on the basis of well‐characterized standards. The results are compared with those obtained in borate buffer (pH 9.3), which have been published previously in this journal.Depending on the potential, cobalt forms two different passive layers. In 0.1 N NaOH (pH 13) the potential range of primary passivity goes from −0.4 to 0.3 VSHE. The passive layer consists of a pure Co(OH)2 film that grows from 10 nm after 5 min of passivation up to 37 nm within 90 min. The layer forms most probably according to a dissolution precipitation mechanism. For E > 0.0 VSHE a thinner layer of only 4 nm (E = 0.2 VSHE for 5 min) is formed. In the range of secondary passivity at E = 0.3–0.8 VSHE Co(III) dominates the layer composition with contributions of Co3O4, CoOOH and Co2O3. After 5 min of passivation the layer thickness in this potential range increases slightly with increasing potential from 4 up to 7 nm. After 90 min the thickness reaches 9 nm, independent of the potential. Copyright © 2002 John Wiley & Sons, Ltd.
Adsorption of released ions from dental amalgams on titanium
Authors: Asami K. , Takada Y. , Okuno O. 
Published: October 2002

AbstractEffects of titanium plate in contact with amalgams of ‘Hi Atomic M’ (HA) and ‘Lumi Alloy’ (LM) on the release of metal ions from those amalgams into 0.9% NaCl solution were investigated using inductively coupled plasma atomic emission spectroscopy, electron probe microanalysis and XPS. Except for Hg, the release of ions increased about ten times on Ti contact, whereas that of Hg was diminished several‐fold. No measurable amounts of Ti ions were found in solution. Where the Ti is in contact with the amalgam, every element was deposited almost proportionally to the solution composition. Tin oxide containing several percent of In2O3 covered the top surface of Ti connected to the conventional HA amalgam. However, the dominant species on Ti connected to the high‐copper LM amalgam were Cu and Sn oxides. On the Ti connected to the amalgams, the concentrations of other elements were very low. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative AES depth profiling of iron and chromium oxides in solid solution, (Cr1−xFex)2O3
Authors: Asteman H. , Norling R. , Svensson J.‐E. , Nylund A. , Nyborg L. 
Published: October 2002

AbstractThis paper presents AES concentration‐dependent sensitivity factors and a method to determine the atomic concentrations of O, Fe and Cr in (Cr1−xFex)2O3 solid solutions. In addition, a solution to the problem of the overlap between the O KVV and Cr LMV peaks is presented. The new approach to evaluate solid solutions of (Cr1−xFex)2O3 then has been used to evaluate the oxide formed on 304L stainless steel oxidized at 600°C in 0.9 bar O2 + 0.1 bar H2O for 168 h. The result shows great improvement in comparison to the conventional quantitative analysis of Auger results. Copyright © 2002 John Wiley & Sons, Ltd.
Auger Si LVV lineshape analysis of porous p‐type silicon electroplated with Fe–Co alloys
Authors: Hamadache F. , Bertrand P. 
Published: October 2002

AbstractDifferent electrochemically produced porous p‐type silicon layers filled with Fe–Co alloys are investigated through AES depth profiling. In this study, we analysed the lineshape changes of the Auger Si LVV transition with the sputter depth and alloy composition. Application of factor analysis to this line, together with Fe and Co LVV transitions, enabled us to identify the dominant chemical state of Si atoms at the pore walls. The structure of the Si LVV lineshape of the metallized porous p‐type silicon compared with that of oxidized porous p‐type silicon suggests that Si atoms are slightly bonded to oxygen. Room‐temperature formation of interfacial Si–Fe–Co compounds is likely to occur upon pore filling with the alloy. This is supported by the change of this lineshape with Fe–Co composition and by the appearance of plasmon loss peaks in the Fe and Co LVV lineshapes. Copyright © 2002 John Wiley & Sons, Ltd.
Factor analysis applied to the study of valence band resonant photoemission spectra in transition‐metal compounds
Authors: Sánchez‐Agudo M. , Soriano L. , Trigo J. F. , Quirós C. , Fuentes G. G. , Morant C. , Elizalde E. , Sanz J. M. 
Published: October 2002

AbstractWe have applied factor analysis to the study of the valence band resonant photoemission spectra of a TiO2 thin film. Classical analysis of the photoemission spectra as a function of the photon energy through the Ti 2p → 3d absorption edge does not give a clear understanding of the resonant process, because the resonance phenomenon is present along the valence band and the only differences on the resonance are related to the distribution of cationic d‐states. However, factor analysis of the spectra allows a more quantitative analysis of the resonance phenomena. Using theoretical partial Ti 3d and O 2p density of states as starting bases in principal component analysis, it is shown that only the hybridized Ti 3d states at the valence band resonate. The Ti 3d constant initial state (CIS) curve maps the Ti 2p x‐ray absorption spectrum. Experimental relative photoemission cross‐sections of the Ti 3d states at the absorption edge (455–470 eV) have been obtained. It is shown that resonant photoemission gives a sixfold enhancement of the Ti 3d cross‐section at 463 eV with respect to the values at energies off‐resonance. Copyright © 2002 John Wiley & Sons, Ltd.
Instrumental effects in the principal component structure of a set of spectra
Authors: Balcerowska G. , Cyrankiewicz M. , Siuda R. , Engelhard H. , Buergener M. , Goldmann A. 
Published: October 2002

AbstractPrincipal components analysis (PCA) is a mathematical technique widely used for the diagnosis of structure in a set of spectra, followed by factor analysis for decomposition of the spectra into physically meaningful constituents. Among the effects that can influence the principal component structure for a set of spectra, one can distinguish effects that come from the imperfect operation of particular devices that constitute the spectrometer. When one wants to apply PCA to detect subtle effects (e.g. very small shifts between spectral lines), then instrumental imperfections disturbing the data cannot be neglected, even if they are not very distinct. This paper reviews, classifies and presents the influence of instrumental effects on the principal component structure of recorded spectra. Copyright © 2002 John Wiley & Sons, Ltd.
XPS and SIMS depth profiling of chlorine in high‐temperature oxynitrides
Authors: Vanzetti L. , Bersani M. , Sbetti M. , Iacob E. , Giubertoni D. , Barozzi M. , Zonca R. , Crivelli B. , Carpanese C. , Zanderigo F. 
Published: October 2002

AbstractThin oxides deposited by low‐pressure chemical vapour deposition (LPCVD) at high temperature are being widely investigated in VLSI technology to be used as possible substitutes for the usual thermal oxides. High‐temperature oxide deposition involves reactions between N2O and dichlorosilane or silane. Considering possible active dielectric applications, the effect of further nitridation and annealing of deposited films has to be considered. Evaluation of the nitrogen content and the distribution profile of these dielectrics then becomes a relevant analytical issue. Moreover, it is also crucial to monitor the amount of possible contaminant species, such as chlorine, introduced by the precursor gases during the deposition. In this work we present the development of an analytical methodology for quantitative depth profiling of chlorine in thin oxides using SIMS and XPS. In addition, the evolution of chlorine distribution in an appropriate set of high‐temperature oxide films submitted to nitridation and further thermal processes will be shown. Copyright © 2002 John Wiley & Sons, Ltd.
The fractured, polished and Ar+‐sputtered surfaces of natural enargite: an XPS study
Authors: Velásquez P. , Ramos‐Barrado J. R. , Leinen D. 
Published: October 2002

AbstractThe natural mineral enargite (Cu3AsS4) has been studied by XPS combined with 4 keV Ar+ depth profiling. The fracture surface, the mechanically polished surface and the 4 keV Ar+‐bombarded enargite surface has been studied by XPS. The fracture surface reveals a stoichiometry in accordance with Cu3AsS4, whereas the polished and the ion‐bombarded surface show strong deviations. In the polished surface a loss of As and Cu leads to polysulphide formation at the sample surface. Enargite subjected to 4 keV Ar+ bombardment reveals a preferential loss of As and, to a lesser extent, sulphur atoms from the sample surface, yielding a steady‐state composition near to chalcocite (Cu2S). The compositional change in the ion‐bombardment‐altered layer is discussed in terms of the thermal spike model, taking into account the volatility of the constituent atoms or possible compounds in the altered layer. Copyright © 2002 John Wiley & Sons, Ltd.
Composition and temperature dependence of Y–Ba–Cu–O high‐temperature superconductor electronic structure
Authors: Shabanova I. N. , Naimushina Ye. A. , Terebova N. S. 
Published: October 2002

AbstractThe electronic structure of YBa2Cu3O7−· was studied by x‐ray electron spectroscopy with variation of the oxygen content and temperature. The use of an x‐ray electron magnetic spectrometer in this research allowed spectra to be obtained in the temperature range from room temperature to the temperature of liquid nitrogen; mechanical cleaning of sample surfaces was performed while taking the XPS spectra. The XPS spectra are compared with the results of the band structure calculations carried out by the full‐potential method of linear muffin‐tin orbitals (FP‐LMTO).It is shown that with an increase in the oxygen content the intensity of the Cu2+ component spectrum increases, which correlates with an increase in the temperature Tc. The increase in intensity of the additional maxima appearing in the O 1s, Ba 3d, Ba 4d spectra is observed in the superconductive state. Copyright © 2002 John Wiley & Sons, Ltd.