bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of polymer topology through late‐transition‐metal catalysis
Authors: Guan Zhibin 
Published: October 2003

AbstractAn Erratum has been published for this article in J Polym Sci Part A: Polym Chem (2004) 42 213In this article, recent examples are reviewed of late‐transition‐metal catalysis applied to polymer topology control. By the judicious selection or design of late‐transition‐metal catalysts, polymers with a broad range of topologies, including linear, short‐chain‐branched, hyperbranched, dendritic, and cyclic topologies, have been successfully synthesized. A distinctive advantage of the catalyst approach is that polymers with complex topologies can be prepared in one pot from simple commercial monomers. A fundamental difference of the catalyst approach with respect to other approaches is that the polymer topology is controlled by the catalysts instead of the monomer structure. In our own laboratory, we have successfully used two strategies to control the polymer topology with late‐transition‐metal catalysts. In the first strategy, hyperbranched polymers are prepared by the direct free‐radical polymerization of divinyl monomers through control of the competition between propagation and chain transfer with a cobalt chain‐transfer catalyst. In the second strategy, polyethylene topology is successfully controlled by the regulation of the competition between propagation and chain walking with the Brookhart PdII‐α‐bisimine catalyst. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3680–3692, 2003
Fuzzy TOPSIS approach for failure mode, effects and criticality analysis
Authors: Braglia Marcello , Frosolini Marco , Montanari Roberto 
Published: October 2003

AbstractIn this paper, an alternative multi‐attribute decision‐making approach for prioritizing failures in failure mode, effects and criticality analysis (FMECA) is presented. The technique is specifically intended to overcome some of the limitations concerning the use of the conventional US MIL‐STD‐1629A method. The approach is based on a fuzzy version of the ‘technique for order preference by similarity to ideal solution’ (TOPSIS).The use of fuzzy logic theory allows one to avoid the intrinsic difficulty encountered in assessing ‘crisp’ values in terms of the three FMECA parameters, namely chance of failure, chance of non‐detection, and severity. With the proposed approach, the definition of a knowledge base supported by several qualitative rule bases is no longer required. To solve the fundamental question of ranking the final fuzzy criticality value, a particular method of classification is adopted, allowing a fast and efficient sorting of the final outcome. An application to an important Italian domestic appliance manufacturer and a comparison with conventional FMECA are reported to demonstrate the characteristics of the proposed method. Finally, a sensitivity analysis of the fuzzy judgement weights has confirmed that the proposed approach gives a reasonable and robust final priority ranking of the different causes of failure. Copyright © 2003 John Wiley & Sons, Ltd.
Implementing Evaluation of the Measurement Process in an Automotive Manufacturer: a Case Study
Authors: Knowles Graeme , Vickers Gordon , Anthony Jiju 
Published: October 2003

AbstractReducing process variability is presently an area of much interest in manufacturing organizations. Programmes such as Six Sigma robustly link the financial performance of the organization to the degree of variability present in the processes and products of the organization. Data, and hence measurement processes, play an important part in driving such programmes and in making key manufacturing decisions. In many organizations, however, little thought is given to the quality of the data generated by such measurement processes. By using potentially flawed data in making fundamental manufacturing decisions, the quality of the decision‐making process is undermined and, potentially, significant costs are incurred. Research in this area is sparse and has concentrated on the technicalities of the methodologies available to assess measurement process capability. Little work has been done on how to operationalize such activities to give maximum benefit. From the perspective of one automotive company, this paper briefly reviews the approaches presently available to assess the quality of data and develops a practical approach, which is based on an existing technical methodology and incorporates simple continuous improvement tools within a framework which facilitates appropriate improvement actions for each process assessed. A case study demonstrates the framework and shows it to be sound, generalizable and highly supportive of continuous improvement goals. Copyright © 2003 John Wiley & Sons, Ltd.
Development of a FTA versus Parts Count Method Model: Comparative FTA
Authors: Arcidiacono G. 
Published: October 2003

AbstractThis study adopts a special Fault Tree Analysis (FTA) method called Comparative FTA to compare the reliability of an electronic braking system with its mechanical counterpart. To this end two Top Events, ‘Ineffective parking braking’ and ‘Wheels jamming during emergency braking’, were analysed. One of the limitations of classic FTA is that the setting up of the tree diagram requires the long‐term involvement—one to two months according to Fiat Auto—of specialists of the system being studied. For this reason, therefore, when dealing with relatively complex systems, classic FTA is only used when safety is involved. This paper introduces a simplified FTA model based on the same principle as the Parts Count Method, which limits its attention to the new branches, thereby avoiding the study of all the branches of the tree, in order to make FTA management easier and to encourage its use. The probability that a Top Event takes place is therefore evaluated by studying the different causes which diversify the solutions considered. This approach is a lean practice to minimize the resources and the time of the analysis. It has guaranteed very satisfactory results and, therefore, Fiat Auto has introduced the practice in their Corporate Instructions. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of plant sterols in hexaploid and tetraploid wheats using gas chromatography with mass spectrometry
Authors: Pelillo Marco , Iafelice Giovanna , Marconi Emanuele , Caboni Maria Fiorenza 
Published: October 2003

AbstractFree sterols from hexaploid and tetraploid free‐threshing wheats (Triticum aestivum L. and T. durum Desf.) and from their respective hulled wheats (T. spelta L. and T. dicoccon Schrank) were analysed by gas chromatography with mass spectrometry. The qualitative analysis of sterols showed a similar pattern either between hexaploid (T. aestivum, T. spelta) and tetraploid (T. durum, T. dicoccon) wheats or between free‐threshing (T. aestivum, T. durum) and hulled (T. spelta, T. dicoccon) wheats. However, quantitative differences were found between tetraploid and hexaploid wheats, in that free sterol amounts in tetraploid wheats were 40% higher than in hexaploid ones. The mass spectra of the sterols were classified into four groups, taking into account the structural features of rings A and B. Typical mass spectral fragmentations of the four classes, and additional evidence related to the side chain of each molecule, were investigated together with their chromatographic behaviour, allowing identification of all the detected sterols. Copyright © 2003 John Wiley & Sons, Ltd.
Analytical method for the quantitative determination of urinary ethylenethiourea by liquid chromatography/electrospray ionization tandem mass spectrometry
Authors: Sottani Cristina , Bettinelli Maurizio , Fiorentino Maria Lorena , Minoia Claudio 
Published: October 2003

AbstractA direct, rapid and selective method for the quantitative determination of the ethylenethiourea (ETU) in human urine has been validated and is reported in the present study. It allows the accurate quantification of ETU in this complex matrix without the use of any internal standard as the sample cleanup is effective enough for the removal of interferences that could lead to ion suppression in the electrospray ionization (ESI) source. This simple and rapid purification system, based on the use of a Fluorosil phase of a BondElut® column followed by a liquid‐liquid extraction procedure, achieves mean extracted recoveries, assessed at three different concentrations (2.5, 10.0, and 25.0 μg/L), always more than 85%. High‐performance liquid chromatography (HPLC) with positive ion tandem mass spectrometry, operating in selected multiple reaction monitoring (MRM) mode, is used to quantify ETU in human urine. The assay is linear over the range 0–50 μg/L, with a lower limit of quantification (LOQ) of 1.5 μg/L and a coefficient of variation (CV) of 8.9%. The lower limit of detection (LOD) is assessed at 0.5 μg/L. The overall precision and accuracy were determined on three different days. The values for within‐ and between‐day precision are ≤ 8.3 and 10.1%, respectively, and the accuracy is in the range 97–118%. The relative uncertainties for the LOQ and QC concentrations have been estimated to be 18 and 8%, respectively. The assay was applied to quantify ETU in human urine from growers that regularly handle ethylenebisdithiocarbamate pesticides in large crop plantations. The biological samples were collected at the start and end of the working day, and the ETU urine levels were found to vary between 1.9 and 8.2 μg/L. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of hydrolysis on the δ13C values of individual amino acids derived from polypeptides and proteins
Authors: Jim Susan , Jones Vicky , Copley Mark S. , Ambrose Stanley H. , Evershed Richard P. 
Published: October 2003

AbstractThis study investigates the effects of hydrolysis on the δ13C values of individual amino acids (IAAs) derived from polypeptide standards, and modern and ancient bone collagen. All IAAs were derivatised to their trifluoroacetyl/isopropyl (TFA/IP) esters for δ13C determination using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Firstly, authentic single poly amino acid standards (SPAAs; n = 5) were hydrolysed for 4, 10, 24 and 48 h. As expected, IAA yields increased as a function of hydrolysis time. Significantly, it was only after 24 h of hydrolysis that IAA δ13C values were statistically identical to bulk SPAA values for all five standards. The accuracy of IAA δ13C values was thus shown to be a function of yield; however, poly phenylalanine demonstrated accurate IAA δ13C values with yields of only 1.4 and 4.3%, after 24 and 48 h of hydrolysis time, respectively. Authentic mixed poly amino acid standards (MPAAs; n = 5) comprising two different amino acids were then hydrolysed for 24 h. Percentage recoveries ranged from 36–95%. Estimates of bulk MPAA δ13C values calculated from measured IAA δ13C values agreed within experimental error with measured bulk MPAA values for three out of the five standards. Finally, the experimental procedure was applied to modern rat (MBCs; n = 20) and ancient ovi‐caprine and bovine (ABCs; n = 27) bone collagen samples where the δ13C values of 12 out of its 18 constituent amino acids were determined. Estimated bulk MBC and ABC δ13C values were calculated from constituent amino acid δ13C values using mass balance. With the exclusion of three ABC samples, calculated bulk bone collagen δ13C values (δ13CBCcal) were shown to correlate extremely well with measured bone collagen values (δ13CBCmes) for both modern and ancient samples, where R2 = 0.91 and 0.84, respectively. Significantly, the variation between calculated and measured bone collagen values (Δ13CBCcal‐BCmes) exhibited similar ranges for both MBC (from −2.6 to +1.2‰) and ABC (from −2.7 to +2.2‰) samples, providing evidence for the preservation of intact collagen in the ancient samples. These results demonstrate that the experimental procedures employed in the acid hydrolytic cleavage of peptides or proteins to their constituent amino acids does not involve significant isotopic fractionation. Copyright © 2003 John Wiley & Sons, Ltd.
Induced in‐source fragmentation for the selective detection of organic bound iodine by liquid chromatography/electrospray mass spectrometry
Authors: Putschew Anke , Jekel Martin 
Published: October 2003

AbstractThe detection of unknown organic compounds, e.g., transformation products of known trace pollutants in environmental samples, is a difficult task which can be simplified if the compounds of interest are characterized by a functional group or a heteroatom which can selectively be detected. For the detection of iodinated benzene derivatives, used as X‐ray contrast media, we have studied whether such compounds can be selectively detected by negative ion (NI) electrospray ionization via iodide as a product ion of in‐source fragmentation, generated by applying a high cone voltage. It was found that selective detection of iodinated benzene derivatives is possible by liquid chromatography/negative ion electrospray ionization (LC/NI‐ESI) if the compounds are destroyed before entering the mass spectrometer. To our knowledge this is the first report of the use of NI in‐source fragmentation MS for analyses traditionally performed with inductively coupled plasma (ICP)‐MS. The novel application of NI in‐source fragmentation MS is a tool for those who do not possess the facilities to perform ICP‐MS. Furthermore, NI‐ESI at varying cone voltages provides both structural information and elemental detection, whereas ICP‐MS can only provide elemental detection. Copyright © 2003 John Wiley & Sons, Ltd.
Chromatographic and mass spectral studies of perfluorooctanesulfonate and three perfluorooctanesulfonamides
Authors: Kuehl D. W. , Rozynov B. 
Published: October 2003

AbstractThe chromatographic and mass spectral characteristics of perfluorooctanesulfonate (PFOS) and three nitrogen‐substituted perfluorooctanesulfonamides have been obtained. A methyl/phenyl mixed‐phase fused‐silica capillary column was used for gas chromatographic (GC) analyses, while a C18 reversed‐phase microbore column was used for liquid chromatographic (LC) analyses. Mass (MS) and tandem mass (MS/MS) spectra were generated using electron ionization (EI), argon CE, methane positive and negative ion CI, and ES ionization modes. EI spectra of the amides showed ions characteristic of both the fluorinated hydrocarbon and the sulfonamide portion of the molecules. The fragmentation pathway was studied using hydrogen/deuterium exchange, and was thought to involve a cyclic intermediate ion. Formation of molecular ions by CE and protonated molecule ions by CI to obtain molecular weight information was only partially successful. Negative ion ES‐MS spectra provided intense [M–H]− anions for the amides, and an [M–K]−anion for PFOS from which molecular weight information could be obtained, while ES‐MS/MS produced product ions that could be used to detect the presence of these compounds in biological or environmental samples. Published in 2003 by John Wiley & Sons, Ltd.
Phosphate buffers in capillary electrophoresis/mass spectrometry using atmospheric pressure photoionization and electrospray ionization
Authors: Nilsson S. L. , Andersson C. , Sjöberg P. J. R , Bylund D. , Petersson P. , Jörntén‐Karlsson M. , Markides K. E. 
Published: October 2003

AbstractCapillary electrophoresis (CE) has been combined with atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) for mass spectrometric (MS) detection. Separation conditions using potassium phosphate buffer and ammonium formate buffer have been compared for analysis of eleven pharmaceutical bases. The results showed improvements in separation efficiency and peak symmetry when phosphate buffer was used. The low flow in CE may enable utilization of these advances with MS detection. Compared with ESI, the APPI technique provided a cluster‐free background. The enhanced signal‐to‐noise ratio in the total ion current (TIC) and the reduced spectral background indicated that the APPI process is less affected by non‐volatile salts in the CE buffers. This results in a wider range of choice of CE buffers in CE/MS analysis when APPI is the ionization method. Copyright © 2003 John Wiley & Sons, Ltd.
Comparative study of matrix‐assisted laser desorption/ionization and gas chromatography for quantitative determination of cocoa butter and cocoa butter equivalent triacylglycerol composition
Authors: Guyon F. , Absalon Ch. , Eloy A. , Salagoity M. H. , Esclapez M. , Medina B. 
Published: October 2003

AbstractThe triacylglycerol (TAG) composition study of cocoa butter (CB) and cocoa butter equivalents (CBEs) has been performed by gas chromatography (GC) and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). These two techniques provided comparable results. The advantage of the MALDI technique was the detection of each compound comprising the triacylglycerol classes (Cn). Moreover, comparison of the data obtained by these two techniques indicated that TAG relative percentages could be obtained quantitatively with the MALDI technique. These techniques have been applied for the composition determination of CB + CBE mixtures. Encouraging results showed that it is possible to quantify an admixture containing as little as 4% of CBE. Copyright © 2003 John Wiley & Sons, Ltd.
Characteristic fragmentation behavior of phosphoamino acid conjugates with 3′‐azido‐3′‐deoxythymidine by electrospray ionization tandem mass spectrometry
Authors: Xiao Qiang , Ju Yong , Zhao Yufen , Cui Yuxin 
Published: October 2003

AbstractThe conjugates of phosphoamino acids with 3′‐azido‐3′‐deoxythymidine were synthesized and their structures were determined by various spectral methods. In positive and negative ion electrospray mass spectrometry (ESI‐MS), the fragmentation pathways were investigated in conjunction with tandem mass spectrometry (MS/MS). The results showed that there were very different characteristic fragment ions in the positive ion MS/MS spectra and the negative ion MS/MS spectra. Copyright © 2003 John Wiley & Sons, Ltd.
Linear quadrupoles with added octopole fields
Authors: Sudakov Michael , Douglas D. J. 
Published: October 2003

AbstractTwo methods of adding relatively small octopole fields to the main quadrupole field of quadrupoles and linear ion traps with cylindrical rods are investigated. The first, ‘stretching’ the quadrupole by moving two rods out from the axis, produces a combination of higher order fields with similar magnitudes in which the octopole field is not necessarily the greatest. The quadrupole field strength is changed significantly and a large potential appears on the axis. The second method uses rod pairs of different diameters. It adds octopole components of up to several percent while all other higher order fields remain small. An axis potential is also added, but it is only a few percent of the radio‐frequency (RF) voltage and approximately equal to the strength of the octopole field. The axis potential can be removed by moving the larger rod pair out from the axis or applying unbalanced RF to the electrodes. Copyright © 2003 John Wiley & Sons, Ltd.
Electrospray ion‐trap multistage mass spectrometry for characterisation of co‐monomer compositional distribution of bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) at the molecular level
Authors: Adamus Grażyna , Sikorska Wanda , Kowalczuk Marek , Noda Isao , Satkowski Michael M. 
Published: October 2003

AbstractWe report an electrospray ionisation multistage mass spectrometry (ESI‐MSn) method that utilises molecular mass information for determination of sequence distribution and chemical structure of mass‐selected macromolecules of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) biopolyester, PHBH. On the basis of ESI‐MSn studies of PHBH oligomers obtained by partial alkaline depolymerisation of natural PHBH containing 13–14 mol% of hydroxyhexanoate (HH) units, the microstructure of this bacterial copolyester was assessed up to the level of 28 repeat units. The subtle structural details of the PHBH were evaluated based on sequencing of individual macromolecular ions thus showing the utility of this technique for the analysis of biological copolyester macromolecules. It was confirmed that both HH and hydroxybutyrate (HB) units of the PHBH copolymer are randomly distributed. Copyright © 2003 John Wiley & Sons, Ltd.
Quantitative analysis of small pharmaceutical drugs using a high repetition rate laser matrix‐assisted laser/desorption ionization source
Authors: Hatsis Panos , Brombacher Stephan , Corr Jay , Kovarik Peter , Volmer Dietrich A. 
Published: October 2003

AbstractIn this work, a high repetition rate laser matrix‐assisted laser desorption/ionization (MALDI) source is studied on a quadrupole‐time‐of‐flight (QqTOF) and a triple quadrupole (QqQ) mass spectrometer for rapid quantification of small pharmaceutical drugs. The high repetition rate laser allows an up to 100‐fold higher pulse frequency as compared with regular MALDI lasers, resulting in much larger sample throughput and number of accumulated spectra. This increases the reproducibility of signal intensities considerably, with average values being around 5% relative standard deviation after taking into account the area ratio of the analyte to an internal standard. Experiments were conducted in MS/MS mode to circumvent the large chemical background due to MALDI matrix ions in the low mass range. The dynamic range of calibration curves on the QqTOF mass spectrometer extended over at least two orders of magnitude, whereas on the QqQ it extended over at least three orders of magnitude. Detection limits ranged from 60–400 pg/μL on the QqTOF and from 6–70 pg/μL on the QqQ for a series of benzodiazepines. The benzodiazepine content of commercial pill formulations was quantified, and less than 5% error was obtained between the present method and the manufacturer's certified values. Furthermore, a high sample throughput was achieved with this method, so that a single MALDI spot could be quantitatively scanned in as little as 15 s, and an entire 96‐well MALDI plate in 24 min. Copyright © 2003 John Wiley & Sons, Ltd.
Quantification of the ratio of positional isomer dilinoleoyl‐oleoyl glycerols in vegetable oils
Authors: Jakab A. , Jablonkai I. , Forgács E. 
Published: October 2003

AbstractThe distribution of fatty acids in a triacylglycerol is of great importance from nutritional, biochemical, quality and technological points of view. The ratio of triacylglycerol positional isomers containing two linoleic acid (18:2) and one oleic acid (18:1) moieties—namely, 1(3),2‐dilinoleoyl‐3(1)‐oleoyl glycerol (LLO) and 1,3‐dilinoleoyl‐2‐oleoyl glycerol (LOL)—were quantified in grape seed, olive, pumpkin seed, soybean, sunflower and wheat germ oils by high‐performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI‐MS) in selected ion monitoring (SIM) mode. Relative LOL contents (LOL/(LLO+LOL)) of the oils were calculated from the mass abundances of the [LL]+ and [LO]+ diacylglycerol fragment ions ([M+H–RCOOH]+) using a calibration curve. The calibration curve of the relative diacylglycerol mass abundances was measured in SIM mode. The relative LOL contents were found to be relatively consistent for each oil variety. The relative LOL content in grape seed, sunflower, pumpkin seed, soybean and wheat germ oils accounted for 44.2 ± 2.6, 26.8 ± 3.2, 16.7 ± 4.6, 15.9 ± 2.9 and 13.9 ± 4.3%, respectively. Only olive oils contained practically 100% of the LLO isomer. These results indicate that the unsaturated fatty acids such as linoleic and oleic acids have ‘non‐random’ distribution patterns in various oils. Copyright © 2003 John Wiley & Sons, Ltd.