bluuebunny/crossref_metadata_2025_split huggingface dataset:
The H and H2 interaction with Pd3Cu, Pd4, and Cu4 fcc (111) clusters: A DFT comparative study
Authors: Bertin V. , Cruz A. , Del Angel G. , Castro M. , Poulain E. 
Published: January 2005

AbstractA comparative study of adsorption of H atoms and H2 molecules on Pd3Cu, Cu4, and Pd4 clusters has been performed through density functional calculations, using the hybrid B3LYP exchange‐correlation functional as implemented in the Gaussian98 program. For Pd atoms the relativistic small‐core effective core potential LANL and LANL2DZ basis set was used and for hydrogen a 6‐31G** basis set was used. The main emphasis is set in the reaction behavior of the different clusters with hydrogen atoms and molecules. We find that full geometry optimization does not appreciably change the metal cluster geometry either for certain reaction modes or the H and H2 capture parameters, but increases the number of reactive sites of the metal clusters. Also, we found that there is charge transfer competition between H and Cu atoms, which drastically diminishes H2 adsorption energy, related to the Pd cluster observed value. Edges and threefold sites are the principal hydrogen adsorption sites. Hydrogen has a great mobility over the metal clusters for different minima, especially when Cu is present; many initial pathways end in the same adsorption site. The observed hydrogen adsorption and binding energies are well reproduced by the calculations. Also, the adsorption mechanisms were determined. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A selective unsaturated hydrocarbon subtraction technique for stable carbon isotopic analysis of atmospheric methyl chloride, methyl bromide, and C2C5 saturated hydrocarbons using continuous‐flow isotope ratio mass spectrometry
Authors: Komatsu Daisuke D. , Tsunogai Urumu , Yamaguchi Junko , Nakagawa Fumiko 
Published: January 2005

AbstractUsing continuous‐flow isotope ratio mass spectrometry, we have developed a new analytical system which enables us to determine the stable carbon isotopic composition of CH3Cl, CH3Br, and C2C5 saturated hydrocarbons in gas samples even if they contain substantial amounts of unsaturated hydrocarbons, using an I2O5 reagent for their selective subtraction. The analytical precision of the δ13C determinations is better than 0.5‰ for >300 pmolC injections and better than 5‰ for 20 pmolC injections. Using the system, δ13C values for CH3Cl and CH3Br were found in burning exhaust that contain a substantial quantity of unsaturated hydrocarbons. CH3Cl and CH3Br measured in exhaust from burning rice plants exhibit highly 13C‐depleted values of −56.6 ± 1.3‰ and −48.6 ± 3.9‰, respectively, while saturated hydrocarbons exhibit δ13C values (−26.4 to −28.9‰) that are comparable with the total δ13C value of the parent material (rice plant; −28.0 ‰). Using the system, we can determine the δ13C values of methyl halides and hydrocarbons in many kinds of gas samples. Copyright © 2005 John Wiley & Sons, Ltd.
A rapid method to determine plasma homocysteine concentration and enrichment by gas chromatography/mass spectrometry
Authors: Valerio Anna , Baldo Goretta , Tessari Paolo 
Published: January 2005

AbstractHomocysteine is an independent risk factor for cardio‐ and/or cerebrovascular diseases. Many methods are used to measure plasma homocysteine levels in physiological fluids. Current gas chromatographic/mass spectrometric (GC/MS) methods allow determination not only of plasma homocysteine concentration, but also of its turnover. However, they have some methodological limitations due to the reduction of disulfide bonds between homocysteine and other thiols or proteins often requiring the use of several very toxic compounds or multi‐step procedures that are particularly time‐consuming, and/or utilize expensive instruments. Herein is described a rapid and precise GS/MS method to determine homocysteine turnover from a relatively low volume of plasma (200 μL). First disulfide bonds were reduced by 2‐mercaptoethanol, which allows the maintenance of the reduced status preventing the rebuilding of the disulfide bond. Then the sample was derivatized to form the bis‐tert‐butyldimethylsilyl derivative. A deuterated internal standard, DL‐[3,3,3′,3′,4,4,4′,4′‐2H8]‐homocystine, was employed to account for losses associated with each analytical step. To evaluate the ‘in vivo’ homocysteine metabolic turnover, [1‐13C]‐methionine was infused and the derived [1‐13C]‐homocysteine quantitated. So a standard curve of [1‐13C]‐homocysteine was prepared by the decomposition of the [1‐13C] methionine. The ions at m/z 325 and 326 were monitored, corresponding to the unlabeled [12C]‐homocysteine and to labeled [13C]‐homocysteine, respectively. The ion at m/z 325 ([M–114)]+) probably resulted from the loss of one derivatizing group to regenerate a free amino group. The intra‐assay coefficient of variation (CV‐intra%) was consistently less than 1.06%, the inter‐assay (CV‐inter%) less than 1.05%. The method described here seems to be simpler, more rapid, and less toxic than those published so far. In particular, its main strength appears to be the degree of precision obtained. We suggest applying this method to the measurement of the ‘in vivo’ rate of production of homocysteine (by the plasma 13C‐homocysteine enrichment) from its precursor (13C‐methionine). Copyright © 2005 John Wiley & Sons, Ltd.
Accurate mass measurement in nano‐electrospray ionization mass spectrometry by alternate switching of high voltage between sample and reference sprayers
Authors: Satomi Yoshinori , Kudo Yoichiro , Sasaki Kyoko , Hase Toshiharu , Takao Toshifumi 
Published: January 2005

AbstractAn electrospray dual sprayer, which generates separate sample and reference sprays by alternately switching the high voltage between the two sprayers, is described. The technique permits accurate mass measurements in nano‐electrospray ionization mass spectrometry (ESI‐MS) to be obtained using a quadrupole/orthogonal acceleration time‐of‐flight mass spectrometer (Q‐TOF). Similar to the method employed with a dual ESI source (Wolff JC et al., Anal. Chem. 2001; 73: 2605), the two sprays are orthogonal with respect to each other, but can be independently sampled without any baffle between these sprays. The reference sprayer is used in the original configuration of the ESI source and was optimized for a 1–2 μL/min flow, whereas the sample sprayer can be either a conventional glass capillary or a borosilicate tip of the type used for nano‐ESI. Both sprayers can be positioned close to the cone so as to give maximum ion currents. The sample and reference sprays are independently generated by raising the potentials on the sample and reference sprayers to 1.4 and 3.0 kV, respectively; the high voltages can be rapidly turned on and off in ca. 1 ms. A nano‐ESI‐MS or nano‐flow LC/ESI‐MS experiment using a Q‐TOF coupled with the above system gave mass accuracies within 3 ppm for measurements of ions up to m/z 1000 using subpicomole samples. Copyright © 2005 John Wiley & Sons, Ltd.
Tandem mass spectrometry of multiply phosphorylated forms of a ‘histidine‐tag’ derived from a recombinant protein kinase expressed in bacteria
Authors: Du Ping , Loulakis Pat , Xie Zhi , Simons Samuel P. , Geoghegan Kieran F. 
Published: January 2005

AbstractWhen a histidine‐tagged form of the protein kinase Aurora‐2 was expressed in Escherichia coli, the purified product carried four to nine phosphate groups, although many fewer were expected. The amino‐terminal tag had the sequence GSSHHHHHHSSGLVPRGSHMK‐. Tryptic digestion of the product followed by analysis by liquid chromatography/mass spectrometry (LC/MS) and tandem mass spectrometry (MS/MS) showed that phosphorylation could occur on the five serine residues of the tag. Mono‐, bis‐, tris‐, tetra‐ and pentaphosphorylated forms of the tag were detected, and their behavior in MS/MS was studied using a quadrupole/time‐of‐flight mass spectrometer. The MS/MS spectra were dominated by the products of neutral loss events (in 98 Da increments, each equivalent to loss of H3PO4), but sufficient b‐ and y‐type sequence ions were detected to allow the locations of the phosphates to be specified in some cases. The assignment of phosphorylation sites for incompletely phosphorylated forms of the tag peptide was challenging, but it appeared that Ser‐10 and Ser‐11 of the tag were more likely to be phosphorylated than Ser‐2 and Ser‐3. Copyright © 2005 John Wiley & Sons, Ltd.
Investigation of the metabolic fate of 2‐, 3‐ and 4‐bromobenzoic acids in bile‐duct‐cannulated rats by inductively coupled plasma mass spectrometry and high‐performance liquid chromatography/inductively coupled plasma mass spectrometry/electrospray mass spectrometry
Authors: Jensen Berit Packert , Smith Christopher J. , Bailey Christopher J. , Rodgers Colin , Wilson Ian D. , Nicholson Jeremy K. 
Published: January 2005

AbstractInductively coupled plasma mass spectrometry (ICPMS) has been used to determine the rate and routes of excretion of bromine following the intraperitoneal administration (50 mg kg−1) of 2‐, 3‐ and 4‐bromobenzoic acids to male bile‐duct‐cannulated rats. Analysis of urine and bile for 79/81Br using ICPMS showed that all three bromobenzoic acids were rapidly excreted (82–98%) within 48 h of dosing, primarily via the urine. High‐performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS) was then used to obtain metabolite profiles for bile and urine. These profiles revealed that extensive metabolism had taken place, with the unchanged bromobenzoic acids forming a minor part of the total of compound‐related material detected. Concomitant MS studies, supplemented by alkaline hydrolysis, enabled the identification of the major metabolite of all three of the bromobenzoic acids as a glycine conjugate. Ester glucuronide conjugates were also identified, but formed only a small proportion of total. Copyright © 2005 John Wiley & Sons, Ltd.
Comparison of primary monoatomic with primary polyatomic ions for the characterisation of polyesters with static secondary ion mass spectrometry
Authors: Van Royen Pieter , Taranu Anca , Van Vaeck Luc 
Published: January 2005

AbstractStatic secondary ion mass spectrometry (S‐SIMS) emerges as one of the most adequate methods for the surface characterisation of polymers with an information depth of essentially one monolayer. The continuing search for increased analytical sensitivity and specificity has led to exploring the use of polyatomic primary ions as an alternative to the traditionally applied monoatomic projectiles. As part of a systematic investigation on polyatomic bombardment of organic and inorganic solids, this paper focuses on selected polyesters. Mass spectra and ion yields are compared for layers deposited on silicon wafers by spincoating solutions with different concentrations of poly(ε‐caprolactone) (PCL), poly(butylene adipate) (PBA) and poly(ethylene adipate) (PEA). Accurate mass measurements have been used to support the assignment of the ions and link the composition of the detected ions to the analyte structure. Use of polyatomic projectiles increases the yield of structural ions with a factor of ±15, ±30 and ±10 for PCL, PBA and PEA, respectively, in comparison to bombardment with Ga+ primary ions, while the molecular specificity is improved by the detection of additional high m/z ions. Copyright © 2005 John Wiley & Sons, Ltd.
Management of the “skills inventory” in times of major change
Authors: Winch Graham W. 
Published: January 2005

AbstractTimes of major change can pose extra‐ordinary challenges to any organisation. Case studies investigating how companies had faced the challenges of a major change in the previous four or five years, and especially how they attempted to prepare their managers for their new roles, revealed that many were ill‐equipped to face the task. One particular result suggested that firms that had relied only on their existing management team and/or on internal promotions had not fared as well as those for whom circumstances permitted the recruitment of new managers to key posts. This observation seems to run counter to the management dictum that firms should always endeavour to hold onto their experienced staff. A simple system dynamics model of a firm's “skills inventory” sheds light on this apparent paradox. The model indicates that in times of stability or slow/incremental change, retaining existing staff is indeed very important. However, in times of major change, as the obsolescence rate of the firm's existing skill base increases rapidly, importing critical skills with new recruits may be the only realistic way of boosting the skill‐base to the necessary levels. This situation is likely to have important competitiveness consequences for firms with traditionally low staff attrition rates, where growth is not creating new post opportunities, or in areas where the external recruitment market offers only limited access to new appointees with advanced skills. Copyright © 2001 John Wiley & Sons, Ltd.
Rerum cognoscere causas: Part I — How do the ideas of system dynamics relate to traditional social theories and the voluntarism/determinism debate?
Authors: Lane David C. 
Published: January 2005

AbstractThis is the first half of a two‐part paper which deals with the social theoretic assumptions underlying system dynamics. The motivation is that clarification in this area can help mainstream social scientists to understand how our field relates to their literature, methods and concerns. Part I has two main sections. The aim of the first is to answer the question: How do the ideas of system dynamics relate to traditional social theories? The theoretic assumptions of the field are seldom explicit but rather are implicit in its practice. The range of system dynamics practice is therefore considered and related to a framework—widely used in both operational research (OR) and systems science—that organises the assumptions behind traditional social theoretic paradigms. Distinct and surprisingly varied groupings of practice are identified, making it difficult to place system dynamics in any one paradigm with any certainty. The difficulties of establishing a social theoretic home for system dynamics are exemplified in the second main section. This is done by considering the question: Is system dynamics deterministic? An analysis shows that attempts to relate system dynamics to strict notions of voluntarism or determinism quickly indicate that the field does not fit with either pole of this dichotomous, and strictly paradigmatic, view. Part I therefore concludes that definitively placing system dynamics with respect to traditional social theories is highly problematic. The scene is therefore set for Part II of the paper, which proposes an innovative and potentially fruitful resolution to this problem. Copyright © 2001 John Wiley & Sons, Ltd.
Experiences and reflections on the transition from classroom to practice
Authors: Haslett Tim 
Published: January 2005

AbstractTranslating university‐based learning to a real‐world context preoccupies many academics. For the systems modelling group at Monash University, the aim is to establish a community of system dynamics practitioners in business and government. System dynamics modelling has been taught at Masters level for the past five years, during which time various methods have been used to affect this translation. These involved varying formats for the major piece assessment, including individual organization‐based projects, case‐study projects and group organization‐based projects. The advantages and disadvantages of these approaches are discussed and some of the insights gained from student feedback and reflection by the teaching staff are presented. Copyright © 2001 John Wiley & Sons, Ltd.
Model‐based scenarios for the epidemiology of HIV/AIDS: the consequences of highly active antiretroviral therapy
Authors: Dangerfield Brian C. , Fang Yongxiang , Roberts Carole A. 
Published: January 2005

AbstractA system dynamics model of HIV/AIDS epidemiology is employed to simulate the effects of triple combination antiretroviral therapy in the treatment of HIV/AIDS. The epidemic data on homosexual men in the UK (1981‐‐1998) have been used to fit the baseline model. The new combination therapies, which supplanted antiviral mono and dual therapy in 1996, are proving to be the most effective prophylaxis yet for halting viral replication in vivo, but many uncertainties still surround their use. A range of model‐generated scenarios are created as a means of considering these uncertainties. Possible futures for the HIV/AIDS epidemic are constructed. Copyright © 2001 John Wiley & Sons, Ltd.
Anomalous strain effect on magnetic properties of La1−xBaxMnO3 epitaxial thin films
Authors: Zhang Jun , Tanaka Hidekazu , Kanki Teruo , Kawai Tomoji 
Published: January 2005

AbstractWe report an anomalous strain effect on magnetic properties in La1−xBaxMnO3 (LBMO) thin films. Epitaxial LBMO films grown on SrTiO3(100) (STO) single‐crystal substrate by pulsed laser deposition suffer strains due to the lattice mismatch between LBMO and STO. For films with x = 0.1 and x = 0.2, tensile strain enhances the ferromagnetic state, resulting in the ferromagnetic Curie temperature TC increasing significantly compared with the corresponding bulk materials. However, for x = 0.3 and x = 0.33, TC decreases in thin films. These results are very different from the previous reported strain effect in other colossal magnetoresistance manganite thin films, and can be interpreted by considering the strain‐induced modification of orbital eg stability. Copyright © 2001 John Wiley & Sons, Ltd.
On the anomalous SIMS transient of B in Si: the influence of surface conditions
Authors: Alkemade P. F. A. , Liu Z. X. 
Published: January 2005

AbstractThe SIMS 11B+ signal from a homogeneously boron‐doped silicon sample was measured with a 1 keV O2+ beam at 60° incidence without oxygen flooding. Stationary levels of boron secondary ions were reached only at a depth of ∼40 nm. In vacuo rotation of the analysed samples during interruption of the profiling revealed that there is no relation between the anomalous long boron transient and the formation of surface ripples by the ion beam. In contrast, removal of the native oxide by HF prior to the SIMS analysis resulted in a reduction of the boron transient to a normal value of ∼6 nm. This work shows that for accurate dynamic SIMS analysis the initial surface condition can be important. Copyright © 2001 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy studies of Ti–Al and Ti–Al–V alloys using Cr Kβ radiation
Authors: Diplas S. , Watts J. F. , Tsakiropoulos P. , Shao G. , Beamson G. , Matthew J. A. D. 
Published: January 2005

AbstractHigh‐energy and conventional x‐ray photoelectron spectroscopy (XPS) using Cr Kβ (hν = 5946.7 eV) and Al Kα (hν = 1486.6 eV) radiation, respectively, were employed to study the alloying behaviour of Ti with Al and V in Ti–Al (Al = 10, 20 and 30 at.%), V–50at.%Al, Ti–35at.%Al–15at.%V, Ti–40at.%Al–20at.%V, Ti–25at.%Al–25at.%V and Ti–50at.%V alloys. The differences of the initial and final state Auger parameters of the elements of interest between unalloyed and alloyed conditions were used to interpret possible charge transfer/redistribution between the elements and to explain subsequent electronic changes occurring upon alloying. The spectroscopic studies were related to thermodynamic predictions and the microstructures of the alloys. The large negative shift of the Al Auger parameter indicated that Al atoms are better screened in the pure metallic environment than in the alloy. This shift was attributed also to the ordering tendency in the Ti–Al and Ti–Al–V alloys, shown by thermodynamic modelling and microstructural studies. Variations of the initial state Auger parameter indicated that initial state effects are significant and may indicate charge transfer from the Al sites towards the transition metal sites. The Auger parameter variations of the transition metals were small, which is in agreement with previous studies. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization of Ge δ‐doped Si(111) with RBS channelling
Authors: Yuhara J. , Morita K. , Falta J. , Müller B. H. , Horn‐von Hoegen M. 
Published: January 2005

AbstractThe crystalline quality of the Si cap layer, the lattice location and the depth distribution of δ‐doped Ge layers in Si(111) crystals grown by molecular beam epitaxy at low and high temperatures have been studied by means of double‐grazing‐angle Rutherford backscattering spectrometry (RBS), RBS channelling and atomic force microscopy. The crystalline quality of the Si cap layer grown at high temperature is excellent, but there are some lattice defects in the interface or in the cap layer grown at low temperature. The RBS channelling measurements show that most of the Ge atoms occupy the Si substitutional sites. The full width at half‐maximum in the depth distribution of δ‐doped Ge in the Si(111) crystal is determined to be 13 ± 5 Å. Copyright © 2001 John Wiley & Sons, Ltd.
The chemical state vector: a new concept for the characterization of oxide interfaces
Authors: Barranco A. , Yubero F. , Espinós J. P. , González‐Elipe A. R. 
Published: January 2005

AbstractFor certain metal oxides deposited as a thin film on the surface of another oxide, changes may occur in the binding energy (BE) of the photoelectron peaks as well as in the kinetic energy (KE) of the Auger peaks of the deposited cation and consequently in its Auger parameter. These changes are illustrated here for the systems formed by SiO2 deposited onto TiO2 and Al2O3. Shifts by −1.3 and −1.0 eV in the Si 2p BE and by 2.3 and 0.7 eV in the KE of the Si KLL Auger peak are found for these two systems when comparing the values obtained for small amounts of SiO2 directly interacting with the support with those of a thick film of this material.The different values of these electronic parameters obtained for increasing amounts of SiO2 can be represented in a Wagner plot. The tendency and magnitude of the changes are similar to those found for Si in phyllosilicate or zeolite compounds with different Si/Al ratios.To systematize these changes in the electronic parameters of the deposited phase the new concept of ‘chemical state vector’ is proposed. It is defined as the vector that connects the two extreme points of a Wagner plot dot graph where the BE of photoelectron peaks is represented versus the KE of the Auger peaks for a cation M of a given MO/M′O interface. The possibilities and limitations of this concept are discussed with regard to the SiO2/TiO2 and SiO2/Al2O3 interface systems reported in this paper and the data for other MO/M′O systems taken from previous works. Copyright © 2001 John Wiley & Sons, Ltd.