bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron ionization induced fragmentation of some oxadiazole and thiadiazole derivatives
Authors: Pihlaja Kalevi , Agirbas Hikmet , Ovcharenko Vladimir , Valtamo Pauliina 
Published: March 2004

AbstractThe mass spectrometric behaviour under electron ionization of several 3,4‐(alkyl/aryl)‐disubstituted 1,2,4‐oxadiazole‐5(4H)‐ones (1–13) and 1,2,4‐thiadiazole‐5(4H)‐thiones (14–17), and that of 3‐aryl‐5‐alkyl‐ or arylthio‐1,2,4‐thiadiazoles (18–24), was studied. These five‐membered rings split similarly to the corresponding 1,2,4‐thiadiazole‐5(4H)‐ones, although substitution has also a clear effect on the routes of fragmentation and the magnitude of secondary processes. In particular, the fragmentation of 1,2,4‐oxadiazole‐5(4H)‐ones (1–6), which do not bear aromatic substituents, was, in addition to the ring ruptures, fairly complicated. The other compounds fragmented more systematically and relatively few unpredictable fragmentations occurred. Copyright © 2004 John Wiley & Sons, Ltd.
Sensitive determination of acidic drugs and triclosan in surface and wastewater by ion‐pair reverse‐phase liquid chromatography/tandem mass spectrometry
Authors: Quintana José Benito , Reemtsma Thorsten 
Published: March 2004

AbstractA new method is presented for the determination of 12 acidic pharmaceuticals (non‐steroidal anti‐inflammatory drugs and bezafibrate), including two metabolites from aqueous samples, together with triclosan as a personal care product. Ion‐pair liquid chromatography (IP‐LC) with electrospray ionisation tandem mass spectrometry (ESI‐MS) in the negative ion mode was employed. The ion‐pairing agent (tri‐n‐butylamine) increased the signal intensity for all acidic analytes and detection limits of 6–200 ng/L were obtained by multiple reaction monitoring. This allows analysis of wastewater samples by direct injection into the LC/MS system without the need for a preceding enrichment step. When combined with a solid‐phase extraction (SPE) step, limits of quantification between 0.15 and 11 ng/L were obtained from 100‐mL sample volumes, which is adequate for most applications. The occurrence of matrix effects was studied and standard addition was required for reliable quantification after SPE from wastewater. The method was finally applied to surface and wastewaters, with analyte concentrations ranging from below the detection limit up to 5.5 μg/L. Copyright © 2004 John Wiley & Sons, Ltd.
Novel experimental arrangement developed for direct fullerene analysis by electrospray time‐of‐flight mass spectrometry
Authors: Kozlovski V. , Brusov V. , Sulimenkov I. , Pikhtelev A. , Dodonov A. 
Published: March 2004

AbstractA novel electrospray setup was found effective for direct analysis of fullerene solutions by electrospray (ES) mass spectrometry. The electrospray capillary needle used for the analysis is equipped with a thin metal (copper, platinum or stainless steel) wire installed inside the capillary. The wire tip protrudes slightly from the capillary end. In this configuration the high electrical field formed by the wire tip stimulates a specific electrospray mode with a fine spray originating from the tip. The correlation of the acquired mass spectra with the magnified view of the spray at the capillary tip was investigated. The effective formation of fullerene ions in both negative and positive ion modes was observed in mass spectra only in the specific case of the electrospray originating from the wire tip. The fullerene di‐anions observed in the negative ES mass spectra provide evidence for the electrochemical nature of this process occurring at the ES capillary tip. Observation of fullerene ions in mass spectra obtained using the suggested electrospray arrangement is assumed to be a consequence of the fine spray originating from the sharp metal wire tip. In this case the liquid/metal interface is near the Taylor cone apex. Copyright © 2004 John Wiley & Sons, Ltd.
High‐throughput simultaneous determination of plasma water deuterium and 18‐oxygen enrichment using a high‐temperature conversion elemental analyzer with isotope ratio mass spectrometry
Authors: Richelle M. , Darimont C. , Piguet‐Welsch C. , Fay L. B. 
Published: March 2004

AbstractThis paper presents a high‐throughput method for the simultaneous determination of deuterium and oxygen‐18 (18O) enrichment of water samples isolated from blood. This analytical method enables rapid and simple determination of these enrichments of microgram quantities of water. Water is converted into hydrogen and carbon monoxide gases by the use of a high‐temperature conversion elemental analyzer (TC‐EA), that are then transferred on‐line into the isotope ratio mass spectrometer. Accuracy determined with the standard light Antartic precipitation (SLAP) and Greenland ice sheet precipitation (GISP) is reliable for deuterium and 18O enrichments. The range of linearity is from 0 up to 0.09 atom percent excess (APE, i.e. −78 up to 5725 delta per mil (dpm)) for deuterium enrichment and from 0 up to 0.17 APE (−11 up to 890 dpm) for 18O enrichment. Memory effects do exist but can be avoided by analyzing the biological samples in quintuplet. This method allows the determination of 1440 samples per week, i.e. 288 biological samples per week. Copyright © 2004 John Wiley & Sons, Ltd.
Anisole, a new dopant for atmospheric pressure photoionization mass spectrometry of low proton affinity, low ionization energy compounds
Authors: Kauppila Tiina J. , Kostiainen Risto , Bruins Andries P. 
Published: March 2004

AbstractAtmospheric pressure photoionization (APPI) is a novel method of ionization in liquid chromatography/mass spectrometry (LC/MS). It was originally developed in order to broaden the range of LC/MS ionizable compounds towards less polar compounds that cannot be analyzed by electrospray (ESI) and atmospheric pressure chemical ionization (APCI). Studies done thus far have shown that non‐polar compounds that earlier were not ionizable in LC/MS can indeed be ionized by the use of APPI. However, the best ionization efficiency for low polarity samples has been achieved with low proton affinity (PA) solvents that are not suitable in reversed‐phase LC (RP‐LC). Here it is demonstrated that the signals for analytes with low proton affinities in acetonitrile can be increased 100‐fold by using anisole as the dopant for APPI, which takes the sensitivity to the same level achieved in the analysis of high PA analytes. Copyright © 2004 John Wiley & Sons, Ltd.
Enhanced responses in matrix‐assisted laser desorption/ionization mass spectrometry of peptides derivatized with arginine via a C‐terminal oxazolone
Authors: Nakazawa Takashi , Yamaguchi Minoru , Nishida Kimiko , Kuyama Hiroki , Obama Takashi , Ando Eiji , Okamura Taka‐aki , Ueyama Norikazu , Tanaka Koichi , Norioka Shigemi 
Published: March 2004

AbstractWe have developed a novel method for enhancing the response of a peptide in matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) by activating the C‐terminal carboxyl group through an oxazolone with which is coupled an amine containing a functional group to help ionize the peptide. The reactions consist of dehydration with acetic anhydride to give an oxazolone, followed by aminolysis with an appropriate amino acid derivative such as arginine methyl ester. The MALDI signal of Ac‐Tyr‐Gly‐Gly‐Phe‐Leu‐Arg‐OMe, thus converted from leucine‐enkephalin, was detected while completely excluding the responses of arginine‐deficient peptides coexisting in the reaction mixture. Some less intense peaks corresponding to a few sequential degradation products, also terminated with the arginine derivative, were also observed. The side‐chain groups potentially that are reactive were conveniently protected by acetylation simultaneous with the C‐terminal activation, and those that remained unprotected were reduced to virtually negligible proportions when the reaction was conducted in a peptide solution of concentration less than 1 mM. The greatly increased responses of such arginine‐terminated peptides could possibly be exploited to discern the C‐terminal tryptic peptide of a protein that is otherwise almost insensitive to MALDI‐MS in general. The simplicity of the post‐source decay spectrum of enkephalin derivatized by arginine methyl ester characteristically accentuated z‐ and b‐type ions, and this should facilitate sequencing of such derivatized peptides. Remaining problems with practical applications of this approach are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Output feedback excitation control of synchronous generators
Authors: Maya‐Ortiz Paul , Espinosa‐Pérez Gerardo 
Published: March 2004

AbstractIn this paper a solution to the output feedback control problem, that improves the transient stability properties, of a single machine infinite bus power system is proposed by designing a nonlinear observer that asymptotically recovers the unmeasurable states of the system. The structure of the closed‐loop system is completed by considering an injection and damping assignment passivity‐based controller for which its stability properties are well established under a state feedback setting. It is shown, by using Lyapunov arguments and as a consequence of the asymptotic stability properties of the closed‐loop system, that the properties of the original state feedback controller are (also asymptotically) recovered. The output feedback design considers that both the load angle and the speed deviation of the machine are measurable and that the mechanical power delivered to the synchronous generator is constant and known, assumptions that allow to treat uncertainty on the operating (equilibrium) point of the system in a simple way. The theoretical results are illustrated via numerical simulations. Copyright © 2004 John Wiley & Sons, Ltd.
On the Validation of SPDM Task Verification Facility
Authors: Ma Ou , Wang Jiegao , Misra Sarthak , Liu Michael 
Published: March 2004

AbstractThis paper describes a methodology for validating a ground‐based, hardware‐in‐the‐loop, space‐robot simulation facility. This facility, called “SPDM task verification facility,” is being developed by the Canadian Space Agency for the purpose of verifying the contact dynamics performance of the special purpose dexterous manipulator (SPDM) performing various maintenance tasks on the International Space Station because the real SPDM cannot be physically tested for 3D operations on the ground due to the gravity. The facility uses a high‐fidelity SPDM mathematical model, known as the “truth model” of the space robot, to drive a hydraulic robot to mimic the space robot performing contact operations. In this research different techniques were studied for practically verifying that the complex simulation facility preserves the dynamics of the truth model of the space robot for space‐representative contact robotic tasks. Based upon the study and many years of experience in developing and verifying space robotic systems, a practical validation strategy including detailed test cases was developed along with a set of quantitative criteria for judging the validation test results. © 2004 Wiley Periodicals, Inc.
3D Cable‐Based Cartesian Metrology System
Authors: Williams Robert L. , Albus James S. , Bostelman Roger V. 
Published: March 2004

AbstractA novel cable‐based metrology system is presented wherein six cables are connected in parallel from ground‐mounted string pots to the moving object or tool of interest. Cartesian pose can be determined for feedback control and other purposes by reading the lengths of the six cables via the string pots and using closed‐form forward pose kinematics. This article focuses on a sculpting metrology tool, assisting a human artist in generating a piece from a computer model, but applications exist in manufacturing, rapid prototyping, robotics, and automated construction. We present experimental data to demonstrate the operation of our system, we study the absolute accuracy and also measurement resolution, and we discuss various error sources. The proposed real‐time cable‐based metrology system is less complex and more economical than existing commercial Cartesian metrology technologies. © 2004 Wiley Periodicals, Inc.
The Synthesis of Three‐Degree‐of‐Freedom Planar Parallel Mechanisms with Revolute Joints (3‐RRR) for an Optimal Singularity‐Free Workspace
Authors: Arsenault Marc , Boudreau Roger 
Published: March 2004

AbstractIn this paper, a method is presented for the synthesis of 3‐RRR planar parallel mechanisms. The method uses a genetic algorithm while considering three different design criteria: the optimization of the mechanism workspace to approach a prescribed workspace, the maximization of the mechanism's dexterity, and the avoidance of singularities inside the mechanism workspace. It is shown that, for a given mechanism, some working modes do not have any corresponding singularity curves located inside the mechanism workspace. Furthermore, a case is presented where, for a given orientation range of the mechanism's end‐effector, there are no parallel singularities located inside the workspace. Finally, two methods are described and compared to deal with the nonuniform units of the mechanism's Jacobian matrix during the dexterity computation. © 2004 Wiley Periodicals, Inc.
Scanning force microscopy and amplitude versus distance measurements on single‐crystal oxide surfaces
Authors: Datar Suwarna , Patil Shivprasad , Iyyer S. B. , Dharmadhikari C. V. 
Published: March 2004

AbstractDynamic mode imaging and investigations on amplitude versus distance measurements were carried out on surfaces of single‐crystal; SrTiO3, Al2O3 and LaAlO3. Experiments were performed to optimize the imaging parameters for surfaces having varying elastic properties. The dependence of the amplitude–distance curve on different materials and the amplitude of oscillation was investigated. For SrTiO3, a low‐drive amplitude provided the linear region necessary for imaging. A large amplitude of oscillation, however, created dips in the amplitude–distance curves, presumably due to complications in the tip dynamics such as bifurcation, period doubling, etc. In the case of Al2O3 and LaAlO3, amplitude–distance curves were characterized by oscillations for lower tip sample separations and step‐like discontinuities in the stiff region. The magnitude of the oscillations and discontinuities was found to decrease with amplitude and eventually could be eliminated. Thus, for these samples a large amplitude of the cantilever provided the linear region required for imaging. It was observed also that two different surfaces of Al2O3 (c‐cut and r‐cut) yield totally different amplitude–distance curves consistent with their standard differences. The results indicate the complex behaviour of amplitude–distance curves, which not only vary from one sample to another but from one surface to another for a given sample. Copyright © 2004 John Wiley & Sons, Ltd.
Report on the 34th IUVSTA workshop ‘XPS: From Spectra to Results—Towards an Expert System’
Authors: Castle J. E. , Powell C. J. 
Published: March 2004

AbstractA summary is given of the workshop entitled ‘XPS: From Spectra to Results–Towards an Expert System’ that was held in St. Malo, France, on 22–26 April 2002 under the sponsorship of the International Union of Vacuum Science, Technique and Applications (IUVSTA). This workshop was held to develop the structure and initial content of a possible future expert system for XPS. Following three plenary presentations, the participants met in six groups to discuss the following topics: instrument and specimen characterization; experimental objectives; wide‐scan interpretation–trial composition and structure; protocols for narrow scans, instrument set‐up and data acquisition; reduction of narrow‐scan data–chemical‐state and morphology analysis; and reduction of narrow‐scan data–quantification. These discussions led to many recommendations for elements of an expert system for XPS. Some of these recommendations are included in this summary but additional recommendations are included in the reports of the six groups available on the internet (http://www.iuvsta.org/W34.html). Copyright © 2004 John Wiley & Sons, Ltd.
Extremely low sputtering degradation of polytetrafluoroethylene by C60 ion beam applied in XPS analysis
Authors: Sanada N. , Yamamoto A. , Oiwa R. , Ohashi Y. 
Published: March 2004

AbstractWe have applied sputtering using a buckminsterfullerene (C60) ion beam for XPS analysis. A practical sputter rate of 2.4 nm min−1 for SiO2 was obtained for sputtering an area of 5 mm × 5 mm using a 5 kV C60 ion beam with an energy of 83 eV per carbon atom. Extremely low sputtering degradation of polytetrafluoroethylene was observed in these conditions. The results were compared with argon ion beam energies of 500 V and 5 kV. These are the first results utilizing a C60 ion beam for XPS analysis with limited sputtering damage. Copyright © 2004 John Wiley & Sons, Ltd.
Subnanometre depth resolution in sputter depth profiling of Si layers using grazing‐incident low‐energy O2+ and Ar+ ions
Authors: Lee Hyung‐Ik , Kim Hyun Kyong , Kim Kyung Joong , Moon Dae Won , Shon Hyun Kyung , Shin Hye Chung , Kang Hee Jae 
Published: March 2004

AbstractThe sputter damage profiles of Si(100) by low‐energy O2+ and Ar+ ion bombardment at various angles of incidence were measured using medium‐energy ion scattering spectroscopy. It was observed that the damaged Si surface layer can be minimized down to 0.5–0.6 nm with grazing‐incident 500 eV Ar+ and O2+ ions at 80°. To illustrate how the damaged layer thickness can be decreased down to 0.5 nm, molecular dynamics simulations were used. The SIMS depth resolution estimated with trailing‐edge decay length for a Ga delta‐layer in Si with grazing‐incident 650 eV O2+ was 0.9 nm, which is in good agreement with the measured damaged layer thickness. Copyright © 2004 John Wiley & Sons, Ltd.
Interpretation of static secondary ion spectra
Authors: Spool A. M. 
Published: March 2004

AbstractA model is presented in which electron impact (EI)/electronic excitation plays a pivotal role in the formation of secondary ions in the SIMS experiment, especially those originating from discrete molecular species. Positive ions are formed by electron loss whereas negative ions are formed by electron capture. Collisions of the new ions with the surface and with other species directly above the sample, along with metastable decay events, reduce the number of odd electron ions detected and produce the changes that make SIMS spectra so different from EI mass spectra. Primary support for this model is gathered from static SIMS spectra themselves, which can be rationalized to a large degree by assuming that the same rearrangement and fragmentation mechanisms that are invoked to explain EI mass spectra take place at the surface after kiloelectron‐volt ion impacts. The static secondary ion spectra of a variety of simple discrete molecular species, of simple hydrocarbons, of monofunctional organic species and of more complicated multifunctional organic species are analyzed in this way and the utility of this model is demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
An interactive method for extracting grammar from programs
Authors: Jain Rahul , Aggarwal Sanjeev Kumar , Jalote Pankaj , Biswas Shiladitya 
Published: March 2004

AbstractThe grammar of the language in which some given code is written is essential for developing automated tools for maintenance, reengineering, and program analysis. Frequently grammar is available for a language but not for its variants that are implemented by various vendors and in which the given code may be written. In this work we address the problem of obtaining the grammar from source code, which can then be used for generating tools for the programs. We propose an incremental method for obtaining grammar for a particular language variant, from a set of programs written in the language variant and an approximate grammar (presumably of the standard language) with some user interaction. We also present the design of a tool for implementing this approach and our experience in working with grammars of C, C++ and COBOL. Copyright © 2004 John Wiley & Sons, Ltd.
Microbenchmarks for determining branch predictor organization
Authors: Milenkovic Milena , Milenkovic Aleksandar , Kulick Jeffrey 
Published: March 2004

AbstractIn order to achieve an optimum performance of a given application on a given computer platform, a program developer or compiler must be aware of computer architecture parameters, including those related to branch predictors. Although dynamic branch predictors are designed with the aim of automatically adapting to changes in branch behavior during program execution, code optimizations based on the information about predictor structure can greatly increase overall program performance. Yet, exact predictor implementations are seldom made public, even though processor manuals provide valuable optimization tips.This paper presents an experimental flow with a series of microbenchmarks that determine the organization and size of a branch predictor using on‐chip performance monitoring registers. Such knowledge can be used either for manual code optimization or for design of new, more architecture‐aware compilers. Three examples illustrate how insight into exact branch predictor organization can be directly applied to code optimization. The proposed experimental flow is illustrated with microbenchmarks tuned for Intel Pentium III and Pentium 4 processors, although they can easily be adapted for other architectures. The described approach can also be used during processor design for performance evaluation of various branch predictor organizations and for testing and validation during implementation. Copyright © 2004 John Wiley & Sons, Ltd.
Agents in object‐oriented software engineering
Authors: Garcia Alessandro F. , de Lucena Carlos J. P. , Cowan Donald D. 
Published: March 2004

AbstractSoftware engineers of multi‐agent systems (MASs) are faced with different concerns such as autonomy, adaptation, interaction, collaboration, learning, and mobility, which are essentially different from classical concerns addressed in object‐oriented software engineering. MAS developers, however, have relied mostly on object‐oriented design techniques and programming languages, such as Java. This often leads to a poor separation of MAS concerns and in turn to the production of MASs that are difficult to maintain and reuse. This paper discusses software engineering approaches for MASs, and presents a new method for integrating agents into object‐oriented software engineering from an early stage of design. The proposed approach encourages the separate handling of MAS concerns, and provides a disciplined scheme for their composition. Our proposal explores the benefits of aspect‐oriented software development for the incorporation of agents into object‐oriented systems. We also illustrate our aspect‐oriented approach through the Portalware multi‐agent system, a Web‐based environment for the development of e‐commerce portals. Copyright © 2004 John Wiley & Sons, Ltd.