bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bio‐affinity characterization mass spectrometry
Authors: Bruce James E. , Anderson Gordon A. , Chen Ruidan , Cheng Xueheng , Gale David C. , Hofstadler Steven A. , Schwartz Brenda L. , Smith Richard D. 
Published: May 2005

AbstractA new approach, bio‐affinity characterization mass spectrometry (BACMS), aimed at providing a more rapid, sensitive and potentially more flexible alternative to techniques presently employed for the characterization of noncovalent interactions in mixtures, such as would be encountered in combinatorial chemistry, is presented. BACMS avoids some of the difficulties and potential artifacts associated with affinity chromatography since the noncovalent associations occur in solution; thus, BACMS avoids the requirement of solid support media and the development of non‐interfering linker species. This paper describes the conceptual basis for the methodology and its potential use in applications which include the screening of high affinity ligands in support of new drug development. BACMS exploits new Fourier‐transform ion cyclotron resonance (FTICR) mass spectrometry technologies which, when coupled to electrospray ionization (ESI), allow the investigation of specific noncovalent complexes formed in solution. BACMS utilizes the well‐known attributes of FTICR, such as the high resolution mass analysis and (MS)n (n ⩾ 2) capabilities; however, it is even more directly a result of recently developed techniques involving quadrupolar excitation, such as selected‐ion accumulation. These tools are demonstrated and the results illustrate the extraordinary sensitivity achievable (solution concentrations of 1 × 10−9 M without the use of separations prior to ESI). Thus, the new capabilities demonstrated here, in conjunction with ESI, will be useful for the investigation of very low relative concentration noncovalent association directly from solution, and promote a faster alternative for combinatorial mixture screening and analysis.
An electrostatic ion guide interface for combining electrospray with Fourier transform ion cyclotron resonance mass spectrometry
Authors: Tang Liang , Hettich Robert L. , Hurst Gregory B. , Buchanan Michelle V. 
Published: May 2005

AbstractA new interface for coupling electrospray (ES) ionization and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry has been developed based on an electrostatic ion guide (EIG). In these initial studies, the EIG interface has been demonstrated to be a simple but effective means of transmitting ES ions generated outside the magnetic field to the FTICR cell. In the current system, the pressures in the EIG region and front FTICR cell are 10−5 and 10−6 Torr, respectively. Under these conditions, ions may be accumulated with low trapping voltages (0.5–0.75 V) and without a high pressure pulse of buffer gas. ES‐FTICR spectra of picomole to femtomole quantities of several peptides, proteins, nucleotides and dinucleotides have been obtained. Modifications currently in progress should enhance performance with respect both to limits of detection and to mass resolution.
Mass spectra of dicarboxylic acid dianilides III. Furan‐based compounds
Authors: Karminski‐Zamola Grace , Fiš;er‐Jakić Lelja , Bajić Miroslav , Boykin David W. 
Published: May 2005

AbstractThe main fragmentation pathways in the mass spectra of five 3,4‐furan‐dicarboxylic acid dianilides are presented and discussed.
Gas‐phase basicities of some amino acid dimers
Authors: Vékey Károly , Czira Gábor 
Published: May 2005

AbstractThis paper gives the first demonstration that the kinetic method can be used to determine molecular pair thermochemical values. Fragmentation of proton‐bound trimers is used to determine the gas‐phase basicities (GB) of molecular dimers (the so‐called molecular‐pair gas‐phase basicities). The set of equations necessary for data evaluation, i.e. extension of the so‐called kinetic method, is discussed. Proton‐bound amino acid trimers have been studied as examples. The GB of glycine dimers (G2) is 190.1 kcal/mol at 970 K, 4.0kcal/mol higher than that of glycine (G). The GB of alanine (A) and valine (V) dimers have also been determined; these are 192.4 (A2) and 194.4 (V2) kcal/mol. The GB of mixed dimers is very close to the average of the respective homo dimers, 191.4 (GA); 192.0 (GV) and 193.2 (AV) kcal/mol. Experimental errors in the relative GB values of various dimers are estimated to be less than 0.3 kcal/mol.
Mass spectrometric study of some zirconocene and hafnocene diadamantanolates
Authors: Grafov Andrei V. , Koval Ludmila I. , Traldi Pietro , Catinella Silvia , Battiston Giovanni A. , Zanella Pierino 
Published: May 2005

AbstractThe electron ionization mass spectrometric behaviour of a new series of hafnocene and zirconocene diadamantanolates is discussed. They are also compared on the basis of mass‐analyzed ion kinetic energy spectrometry. Fragmentation patterns of the complexes in question give relevant information on their gas‐phase behaviour as MO2/MC (M = Zr, Hf) precursors for metal‐organic chemical vapour deposition.
A new hybrid mass spectrometer for the investigation of ion/molecule reactions
Authors: Flammang Robert , Van Haverbeke Yves , Braybrook Carl , Brown Jeff 
Published: May 2005

AbstractAn RF‐only quadrupole collision cell, fitted with retardation and acceleration lenses, has been installed in a field‐free region of a large‐scale tandem mass spectrometer. This new arrangement has allowed decelerated, mass‐selected ions (ca. 5 eV kinetic energy) to react with reagent gases and reaccelerated, mass‐selected products (ca. 8 keV) to be subsequently identified by collisional activation mass spectrometry. The system was tested by looking at ion/molecule reactions of cyclobutanone molecular ions, previously studied by FTICR mass spectrormetry.
The diagnostic value of the m/z 102 peak in the positive‐ion fast‐atom bombardment mass spectra of peptides
Authors: van Dongen W. D. , Heerma W. , Haverkamp J. , de Koster C. G. 
Published: May 2005

AbstractThe mass spectrometric characteristics of a number of different m/z 102 ions, which might occur in the fast‐atom bombardment mass spectra of peptides, appeared to be sufficiently different for an unequivocal structural assignment and they have successfully been applied in the structural analysis of an unknown. Special attention has been paid to the structure of m/z 102 ions from threonine‐containing compounds. Attempts to generate m/z 102 product ions from peptides containing threonine at the N‐terminus were not successful. From experiments with 18O‐labelled threonine it was concluded that the side‐chain hydroxyl group is exclusively involved in the water loss from protonated threonine. Based on ab initio calculations of feasible m/z 102 production structures, N‐protonated dehydroamino‐2‐butyric acid from protonated threonine and peptides containing threonine at the C‐terminus seems to be the most likely product‐ion structure. Although relative stability calculations revealed that the threonine B1‐type ion has the lowest heat of formation, it could also be concluded that a B1‐type ion from threonine should be considered as an electrostatically bound ion/molecule complex, which will immediately dissociate into a threonine immonium ion (A1) and a carbon monoxide molecule. The energy requirement for this fragmentation reaction (B1→A1 + CO) is less than 7 kJ/mol without an energy barrier, which makes B1‐type ions of threonine unlikely to exist in the gas phase.
The unimolecular chemistry of the enol of ionized methyl glycolate: Formation of the hydrogen‐bridged radical cation [CH3O(H)…︁H…︁OCH].+
Authors: Suh Dennis , Terlouw Johan K. , Burgers Peter C. 
Published: May 2005

AbstractDissociative ionization of methyl 2‐hydroxy‐isovalerate and dimethyl tartrate cleanly generate, via McLafferty rearrangements, the 1‐methoxy‐ethene‐1,2‐diol ion HOCHC(OH)OCH, 2. The unimolecular chemistry of 2, the enol form of ionized methyl glycolate, HOCH2C(O)OCH, 1, was investigated by a variety of tandem‐mass spectrometry‐based techniques using D‐ and 18O‐labelled precursor molecules. The enol ion undergoes four major dissociations viz. loss of CH, CO, CH3OH and C2HO. Loss of CH involves isomerization of 2, via a 1,4 H shift, into the distonic ion HC(O.)C(OH)O+(H)CH3, 4, followed by direct bond cleavage yielding the product ion HC(O)C(OH). A second 1,4 H shift yields the hydroxyketene/methanol ion–dipole complex which serves as the precursor for the losses of CH3OH and C2HO, yielding HO(H)CCO+· and CH3OH respectively. A further isomerization step leads to the loss of CO, yielding the O…︁H ⃛O bridged ion [CH3O(H) ⃛H…︁ OCH]+·, one of the most stable isomers on the C2H6O potential energy surface. Ionized methyl acetate, CH3C(O)OCH and related aliphatic esters, readily interconvert with their enol isomers prior to dissociation, but no such tautomerization occurs in 1. This is because the HOCH functionality opens up facile rearrangement/dissociation pathways in 1 and 2 whose energy requirements lie below the tautomerization barrier 1→2.
Procedures for detection of DNA by matrix‐assisted laser desorption/ionization mass spectrometry using a modified nafion film substrate
Authors: Bai Jian , Liu Yan‐Hui , Liang Xiaoli , Zhu Yongdong , Lubman David M. 
Published: May 2005

AbstractA Nafion film substrate modified with concentrated ammonia was shown to improve the detection of DNA using matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS), especially for DNA strands greater than 200 base pairs. Experimental procedures relating to the detection of DNA by MALDI‐MS using this modified Nafion substrate are described.
Charge separation reaction dynamics from pepipico using a position‐sensitive detector
Authors: Hsieh S. , Eland J. H. D. 
Published: May 2005

AbstractThe combination of a position‐sensitive detector with the photoelectron–photoion–photoion coincidence (PEPIPICO) technique allows complete determination of the laboratory momenta and angles of ions in coincidence. The technique yields angular distributions of fragment ions, high resolution kinetic energy distributions for two‐body reactions and Newton diagrams for three‐body dication dissociation. The reactions SF→F++SF+F2 and cyclo‐C4F→CF+C2F+CF are shown to follow sequential mechanisms as determined previously. The technique's potential for elucidating more complex reactions is illustrated for SO→O++S++O and CF3I2+→CF+I++F, which show variations in mechanism as a function of total kinetic energy release.
A Faraday cup detector for high‐mass ions in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Imrie D. C. , Pentney J. M. , Cottrell J. S. 
Published: May 2005

AbstractA detector has been developed, which collects and amplifies the electric charge of an incoming bunch of ions, for use in matrix‐assisted laser desorption/ionization (MALDI) time‐of‐flight (TOF) mass spectrometry. The detector has a time‐of‐flight resolution of about 50 ns and a noise level of 750 electrons rms. It has been tested in a Finnigan LaserMAT spectrometer with a number of samples which Were expected to give reliable results in MALDI time‐of‐flight mass spectrometry. Clear mass peaks have been observed from samples with masses above 300 kDa.
Electron impact mass spectra of some 1‐(2‐furyl)‐ and 1‐(2‐thienyl)‐2‐(2‐benzothiazolyl)ethenes
Authors: Karminski‐Zamola Grace , Tralić‐Kulenović Vesna , Fišer‐Jakić Lelja , Bajić Miroslav , Boykin David W. 
Published: May 2005

AbstractThe electron impact mass spectra of some 1‐(2‐furyl)‐ and 1‐(2‐thienyl)‐2‐(2‐benzothiazolyl) ethenes have been recorded and the identity of various ions in the mass spectra established. The compounds examined (1–10) exhibit two main fragmentation routes. On one hand, fragmentation of the furan and thiophene nuclei and the formation of cyclopropenylethyne cations with very significant abundance and on the other hand, fragmentation of the benzothiazole nuclei on characteristic pathways. Compounds 6–10 also show two additional fragmentation routes.
Investigation of crudes of synthesis of [Leu31, Pro34]‐neuropeptide Y by capillary zone electrophoresis/mass spectrometry
Authors: Zaramella Alessio , Curcuruto Ornella , Hamdan Mahmoud , Cabrele Chiara , Peggion Evaristo 
Published: May 2005

Abstract[Leu31, Pro34]‐Neuropeptide Y is a thirty‐six amino‐acid peptide which has a measured relative molecular mass of 4222. Solid‐phase synthesis of this peptide resulted in complex crudes of synthesis which were examined by capillary zone electrophoresis (CZE)/electrospray ionization mass spectrometry (ES‐MS). The separation efficiency of CZE combined with the mass specificity of mass spectrometry yielded rapid and reliable information on the target peptide and a number of associated side products, which were mainly acetylated peptide sequences having relative molecular masses in the range 2240–4101. Such incomplete or, as they are commonly called, difficult sequences are provoked by problems of swelling and aggregation of the growing peptide chains in the course of synthesis. The use of mass spectrometry is indispensable for obtaining reliable information on the inevitable side products. Initial tuning of the ion source and optimization of the coupling between the CZE system and the mass spectrometer were achieved by performing a number of measurements pertaining to artificially made mixtures of commercial neuropeptides.
Synthetic pyrethroid insecticides analysis by gas chromatography/mass spectrometry operated in negative‐ion chemical ionization mode in soil, moss and fish tissue
Authors: Yasin M. , Baugh P. J. , Hancock P. , Bonwick G. A. , Davies D. H. , Armitage R. 
Published: May 2005

AbstractA gas chromatographic/mass spectrometric method was developed for the simultaneous determination of five synthetic pyrethroid insecticides in soil, moss and fish tissue. These pyrethroids were extracted with hexane‐dichloromethane by ultrasonication and cleaned up on Florisil (soil and moss) and mixed acid/base alumina (fish) columns prior to determination by gas chromatography/negative‐ion chemical ionization mass spectrometry in selected ion monitoring mode. All the pyrethroids were analyzed simultaneously in a single run on a DB5‐MS 15 m capillary column. Recoveries of the pyrethroids from the three matrices at fortification levels of 10, 50 and 100 μg/kg ranged from 80 to 117%. Four determinations were made at each concentration level for each matrix. The practical determination limit of the method was in the range 0.5 to 5 μg/kg depending on the compound. This method was also applied to samples obtained from a contaminated ecosystem.
Combinatorial chemistry: Direct analysis of bead surface associated materials
Authors: Haskins Neville J. , Hunter David J. , Rahman Shahzad S. , Organ Andrew J. , Thom Catriona 
Published: May 2005

AbstractMatrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry has been used to analyse the results of solid‐phase combinatorial chemistry on a single bead. A single component from a five‐membered combinatorial library was positively identified using the method outlined in this paper.
A computer‐based method to increase the signal‐to‐noise ratio of negative‐ion currents in double‐charge‐transfer spectroscopy
Authors: Bayliss Mark A. , Harris Frank M. , Parry David E. , Evans Stephen 
Published: May 2005

AbstractDouble‐charge‐transfer spectroscopy is routinely used to measure double‐ionization energies of molecules to singlet and triplet electronic states of dications, but is experimentally difficult to apply because the yield of negative ions generated in the double‐electron‐capture reactions is low. The use of a data‐acquisition system and repetitive scanning of a spectrum can increase signal‐to‐noise ratios, but the number of scans that can be acquired is limited by drifting in the spectrum position, which results in spectral‐peak broadening. This limitation has been overcome in the present investigation by the application of a computer enhancement program that effectively superimposes successive spectra which are subject to slight drift. Spectra obtained for H+ projectile ions reacting with hexafluorobenzene (C6F6) molecules are presented; use of the program with such spectra reveals features in the computer‐enhanced spectrum which are not clearly evident in the individual spectra.
Surface transient effects in ultralow‐energy O2+ sputtering of silicon
Authors: Chanbasha A. R. , Wee A. T. S. 
Published: May 2005

AbstractIt is known that by lowering the impact energy the sputter rate and surface transient width in SIMS will be reduced. However, few studies have been done at ultralow energies over a wide range of impact angles. This study examines the dependence of sputter rate and transient width as a function of O2+ primary ion energy (Ep = 250 eV, 500 eV and 1 keV) and incidence angles of 0–70°. The instrument used is the Atomika 4500 SIMS depth profiler and the sample was Si with 10 delta‐layers of Si0.7Ge0.3. We observed that the lowest transient width of 0.7 nm is obtainable at normal and near‐normal incidence with Ep ∼ 250 eV and Ep ∼ 500 eV. There is no significant improvement in transient width going down in energy from Ep ∼ 500 to ∼250 eV. The onset of roughening is also not obvious at Ep ∼ 250 eV over the whole angular range studied. Although the sputter rate during the surface transient is normally different from that at steady state, only at Ep ∼ 250 eV was it observed that the sputter rate remained fairly independent of depth. We conclude that the best working ranges to achieve a narrow transient width and accurate depth calibration are at Ep ∼ 250 eV/0° < θ < 20°and 500 eV/0°< θ < 10°. Copyright © 2005 John Wiley & Sons, Ltd.
Characterization of etched glass surfaces by wave scattering
Authors: Jafari G. R. , Mahdavi S. M. , Iraji Zad A. , Kaghazchi P. 
Published: May 2005

AbstractThe roughness of glass surfaces after different stages of etching is investigated by reflection measurements with a spectrophotometer, light scattering, atomic force microscopy (AFM, on a small scale) and profilometry (on a large scale). The results suggest that there are three regimes during etching, according to their optical reflectivity and roughness. The first and the second regimes are studied by the Kirchhoff theory and the third one is studied by the optical geometric theory. Also, the roughness obtained by optical scattering is compared with the AFM results. Copyright © 2005 John Wiley & Sons, Ltd.
Topological properties for characterizing well‐formedness of process components
Authors: Thu Tran Dan , Nhi Tran Hanh , Bich Thuy Dong Thi , Coulette Bernard , Cregut Xavier 
Published: May 2005

AbstractRHODES is an environment for modelling software processes, in which software processes are described by using a Process Modelling Language called PBOOL+. In this environment, a software process is built from PBOOL+ process components that can be reused to construct other processes. To identify well‐formed process components, we study properties to be able to characterize topological structure of the components. These properties should relate intrinsically to cohesion of a component, and coupling between components. We will consider two classical properties that originated from graph theory, which are connection and transitive closure. These two properties are sometimes too strict to be applied, so we propose several weaker properties that are still useful for characterizing good components. The article aims to present these topological properties and their applications to reusable process components in context of the RHODES environment. Copyright © 2005 John Wiley & Sons, Ltd.
Four mechanisms for adaptable systems: a meta‐level approach to building a software product line
Authors: Fritsch Claudia , Renz Burkhardt 
Published: May 2005

AbstractMeta‐level architectures combined with domain‐specific languages serve as a powerful tool to build and maintain a software product line: Meta‐level architectures lead to adaptable software systems. Executable descriptions capture expert knowledge.We have developed a meta‐level architecture for a software product line of legal expert systems. Four meta‐level mechanisms support both variability and evolution of the product line. Domain analysis had shown that separation of expert knowledge from technical code was essential. Descriptions written in domain‐specific languages reside in the meta level, and serve as specification, code, and documentation. Technical code finds its place in interpreting machines in the base level.We discuss how meta‐level architectures influence the qualities of software product lines and how properties and patterns of the problem space can guide the design of domain‐specific languages. Copyright © 2005 John Wiley & Sons, Ltd.
An evaluation of CMMI process areas for small‐ to medium‐sized software development organisations
Authors: Wilkie F. G. , McFall D. , McCaffery F. 
Published: May 2005

AbstractIn this article, we describe the results of CMMI software process appraisal work with six small‐ to medium‐sized software development companies. Our analysis of six CMMI process areas appraised within each of these organisations is presented. Commonly practiced or not practiced elements of the model are identified, leading to the notion of perceived value associated with each specific CMMI practice. A finer‐grained framework, which encompasses the notion of perceived value within specific practices, is presented. We argue that such a framework provides incentive to small‐ to medium‐sized enterprises starting process improvement programmes. Copyright © 2005 John Wiley & Sons, Ltd.
Staged configuration through specialization and multilevel configuration of feature models
Authors: Czarnecki Krzysztof , Helsen Simon , Eisenecker Ulrich 
Published: May 2005

AbstractFeature modeling is a key technique for capturing commonalities and variabilities in system families and product lines. In this article, we propose a cardinality‐based notation for feature modeling, which integrates a number of existing extensions of previous approaches. We then introduce and motivate the novel concept of staged configuration. Staged configuration can be achieved by the stepwise specialization of feature models or by multilevel configuration, where the configuration choices available in each stage are defined by separate feature models. Staged configuration is important because, in a realistic development process, different groups and different people make product configuration choices in different stages. Finally, we also discuss how multilevel configuration avoids a breakdown between the different abstraction levels of individual features. This problem, sometimes referred to as 'analysis paralysis', easily occurs in feature modeling because features can denote entities at arbitrary levels of abstraction within a system family. Copyright © 2005 John Wiley & Sons, Ltd.
Löslichkeit von Mangandioxyd unter dem Einflusse von metallischem Quecksilber
Authors: Meyer Julius , Kanters Robert 
Published: May 2005

AbstractWährend sich weder Mangandioxyd noch metallisches Quecksilber in kalter verdünnter Schwefel‐oder Salpetersäure auflöst, geben beide zusammen infolge einer gekoppelten Reaktion

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leicht in Lösung. Die Versuchsbedingungen und der quantitative Verlauf dieser Umsetzung wurden untersucht und darauf hingewiesen, daß diese merkwürdige Auflösung sich vielleicht beim Lagern von Trockenelementen zerstörend bemerkbar machen kann.