bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification and characterization of Fenton oxidation products of surfactants by electrospray mass spectrometry and solid phase microextraction gas chromatography/mass spectrometry. 3. Polyethoxylated fatty alcohols and nonylphenols
Authors: Cuzzola Angela , Raffaelli Andrea , Saba Alessandro , Salvadori Piero 
Published: August 2002

AbstractThe Fenton reaction for the degradation of surfactants has been investigated and partial degradation products have been identified and characterized by mass spectrometry for the case of polyethoxylated nonylphenols and fatty alcohols with an average ethoxylation number of 7. The polar water‐soluble products were investigated by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI), and the volatile products leaving the mixture during the reaction were trapped by means of solid phase microextraction (SPME) and investigated by gas chromatography/mass spectrometry (GC/MS) with EI and CI ionization. The reaction leads to the shortening of the ethoxylic chain and to the oxidation of the terminal part. The formation of volatile aldehydes is also observed, corresponding to fragmentation between the hydrophobic part and the polar head. The extent of mineralization is dependent on peroxide and iron(II) concentrations. Copyright © 2001 John Wiley & Sons, Ltd.
Screening combinatorial libraries for optimal enzyme substrates by mass spectrometry
Authors: Wang Peng , Snavley Donald F. , Freitas Michael A. , Pei Dehua 
Published: August 2002

AbstractA method has been developed for the rapid identification of optimal enzyme substrates from combinatorial libraries. This methodology was validated by screening a 361‐member N‐terminally formylated tripeptide library, f‐XXR (X = 19 different amino acids), for optimal substrates of Escherichia coli peptide deformylase (PDF). The library was synthesized on a solid phase via the split‐pool synthesis method. The N‐terminal formyl group was added by treating the resin with a 1:1 (mol/mol) mixture of HCO2H and DCO2D in the presence of dicyclohexylcarbodiimide. In a mass spectrum, each member of the library produced a doublet peak (separated by 1.0063 Da). Limited treatment of this library with E. coli PDF resulted in the deformylation of those peptides that are the most efficient substrates of the enzyme. The deformylated products, due to loss of the mass‐degenerate formyl group, each generated a singlet peak in the mass spectrum. Thus, the PDF product peaks were readily identified and sequenced via tandem mass spectrometry. The results showed that PDF strongly prefers a norleucine and, to a lesser extent, a phenylalanine as the N‐terminal residue, whereas it has little selectivity at the penultimate position. This result is in excellent agreement with the literature data and therefore demonstrates the methodology as an effective approach to the identification of optimal enzyme substrates. This method should be generally applicable to other enzymes as well as synthetic catalysts. Copyright © 2001 John Wiley & Sons, Ltd.
Time‐of‐flight mass spectrometric analysis of ion formation in hypervelocity impact of organic polymer microspheres: comparison with secondary ion mass spectrometry, 252Cf mass spectrometry and laser mass spectrometry
Authors: Kissel Jochen , Krueger Franz R. 
Published: August 2002

AbstractUnisized 1.6‐µm polystyrene microspheres coated with PEDOT (polyethylene‐dioxythiophene) were accelerated to speeds of 6–16 km/s and shot onto a silver target. Either positive or negative ions, both instantaneously formed by the impact process, have been analyzed by time‐of‐flight mass spectrometry (TOF). Apparently, the processes that control the formation of ions of either polarity depend on the impact velocity. Comparing the results with those of secondary ion mass spectrometry with primary ion energy in both the elastic and the inelastic (252Cf‐MS) energy loss regimes, some reaction mechanisms of the polymer ions for different energy densities could be elucidated. Some aspects of ion formation are also related to those found in pulsed laser ion generation from these microspheres. This investigation was performed in order to further improve the method of analyzing the organic fraction of interstellar, interplanetary, and cometary dust particles impinging on the targets of the ‘CIDA’ time‐of‐flight (TOF) mass spectrometers on‐board the NASA comet missions ‘STARDUST’ and ‘CONTOUR’. Copyright © 2001 John Wiley & Sons, Ltd.
Friction analysis based on integral quadratic constraints
Authors: Rantzer A. 
Published: August 2002

AbstractPassivity arguments have long been used in the analysis of systems with friction. This paper proves a new set of integral quadratic constraints, which reduces the conservatism of such methods. The result is used to derive a quantitative bound on the amount of integrator leakage that is needed to remove stiction‐induced oscillations in a servo system.Finally, an incremental version of the circle criterion is used to study the existence of subharmonics due to friction in a system subject to externally forced oscillations. Copyright © 2001 John Wiley & Sons, Ltd.
Quantification from overlapping Auger peak‐to‐peak heights
Authors: Asante J. K. O. , Roos W. D. , Maritz M. F. 
Published: August 2002

AbstractAuger peak‐to‐ peak‐heights (APPHs) in the derivative Auger spectra can be used during quantification to determine the fractions contributing to the Auger yield. The calculated APPH is stored during sampling, whereas the spectra are sometimes discarded. When peaks overlap, only the APPH of the combined spectrum is stored. In such cases, where the original spectra are no longer available, it is impossible to extract the contribution of each of the species from a single APPH. However, if APPHs have been sampled in two separate energy regions, both with overlapping peaks of the same species, it is possible again to extract the individual contributions provided that standards of both species (taken under similar conditions) are available. Because the APPH of the sum of two spectra is not the sum of the APPHs of the contributing spectra, the procedure involves simultaneous solution of two non‐linear equations. Copyright © 2001 John Wiley & Sons, Ltd.
Detachment of alumina films from aluminium by 100 keV H+ ions
Authors: Liu Y. , Alexander M. , Koroleva E. , Skeldon P. , Thompson G. E. , Bailey P. , Noakes T. C. Q. , Shimizu K. , Habazaki H. 
Published: August 2002

AbstractIrradiation of aluminium covered by anodic oxide films 3–14 nm thick using 100 keV H+ ions is shown to result in detachment of the oxide film. A dose of 6.6 × 1016 H+ ions cm−2 on a 6.5 nm thick film causes the removal of large pieces of oxide with dimensions at least 15 µm. Atomic force microscopy analysis shows that the location of the failure is within ∼1 nm of the metal/oxide interface. The large aspect ratio (width to thickness) of the detached pieces is thus ∼2000 : 1 and indicates that there is a disruption of the oxide bonding over large areas. The bombardment also results in the formation of blisters with diameters up to several hundred nanometres in the oxide, accompanied by shallow depressions, ∼5 nm deep in the underlying metal. The detachment is suggested to be associated with either condensation of vacancies generated in the metal by the H+ ions or accumulation of hydrogen atoms deposited in the metal by the ion beam in the region of the metal/oxide interface. Although the beam energy and dose were expected to cause some disruption in the implanted material, the complete detachment of large areas of oxide was not anticipated. In fact, this appears to be the first time such gross detachment of an anodic film by H+ ion irradiation has been reported. Copyright © 2002 John Wiley & Sons, Ltd.
Estimating cancer prevalence using mixture models for cancer survival
Authors: Phillips Norman , Coldman Andrew , McBride Mary L. 
Published: August 2002

AbstractKnowledge of cancer prevalence is useful for estimating the ongoing level of resources utilized in the treatment of disease and is of some public health interest. Cancer prevalence is estimated first as the proportion of persons previously diagnosed (PD) with cancer that are still alive; and second as the proportion of individuals in the population who were previously diagnosed with cancer and who have not been cured (NC). The proportion of cases that are cured is estimated by assuming that the cured and uncured cases have distinct survival patterns. The hazard for cured cases is assumed to be a multiple of the hazard from causes other than cancer in the general population. The hazard for uncured cases is assumed to have two independent components: one corresponding to the disease‐specific hazard, and the other a multiple of the population hazard from ‘other causes’. Future prevalence estimates are obtained by projecting the survival of current prevalent cases as well as the survival of future incident cases. Copyright © 2002 John Wiley & Sons, Ltd.
Use of a density equalizing map projection in analysing childhood cancer in four California counties
Authors: Merrill Deane W. 
Published: August 2002

AbstractIn this study, 401 cases of childhood cancer in four California counties in 1980–1988 were analysed with the innovative methodology of density equalizing map projections. The data were originally collected and analysed by the California State Department of Health Services (DHS). In addition to the new analytic technique, the present analysis used population data more detailed and more accurate than those in the DHS analysis. The geographic boundaries of the 259 census tracts in the study area were adjusted according to population at risk so as to make population density everywhere constant; then the 401 case locations were plotted on the density equalized map. If risk is everywhere equal, the resulting distribution of cases should be uniform except for statistical variation. The metric used was a measure of the variability of the density of cases on the density equalized map. The same metric was calculated for independent samples of artificial cases, generated under the null hypothesis of equal risk. The slight geographic non‐uniformity observed among the real cases is well within the limits of variation observed in the samples of artificial cases. In agreement with results published by DHS, we conclude that there is no evidence for geographic variation of risk among the cases studied. Subsets of the data, selected by age, sex, race, time period and cancer site, yielded similar negative results. Copyright © 2001 John Wiley & Sons, Ltd.
A generalized concordance correlation coefficient for continuous and categorical data
Authors: King Tonya S. , Chinchilli Vernon M. 
Published: August 2002

AbstractThis paper discusses a generalized version of the concordance correlation coefficient for agreement data. The concordance correlation coefficient evaluates the accuracy and precision between two measures, and is based on the expected value of the squared function of distance. We have generalized this coefficient by applying alternative functions of distance to produce more robust versions of the concordance correlation coefficient. In this paper we extend the application of this class of estimators to categorical data as well, and demonstrate similarities to the kappa and weighted kappa statistics. We also introduce a stratified concordance correlation coefficient which adjusts for explanatory factors, and an extended concordance correlation coefficient which measures agreement among more than two responses. With these extensions, the generalized concordance correlation coefficient provides a unifying approach to assessing agreement among two or more measures that are either continuous or categorical in scale. Copyright © 2001 John Wiley & Sons, Ltd.
Automated analysis, verification and testing
Authors: Tracey Nigel , Penix John , Visser Willem 
Published: August 2002

AbstractIn Software Testing, Verification and Reliability, NIGEL TRACEY, JOHN PENIX and WILLEM VISSER present a special issue for researchers and developers interested in automated verification, analysis and testing of software, exploring new collaborations and aiming to increase the level of co‐operation between communities. Copyright © 2001 John Wiley & Sons, Ltd.
Expression and acquisition of the conditioned place preference response to cocaine in rats is blocked by selective inhibitors of the enzyme N‐acetylated‐α‐linked‐acidic dipeptidase (NAALADASE)
Authors: Slusher Barbara S. , Thomas Ajit , Paul Mousumi , Schad Christina A. , Ashby Charles R. 
Published: August 2002

AbstractIn this study we examined the effect of 2‐(phosphonomethyl)pentanedioic acid (2‐PMPA) and GPI 5693, selective inhibitors of the enzyme N‐Acetylated‐α‐Linked‐Acidic Dipeptidase (NAALADase; glutamate carboxypeptidase II; EC no. 3.4.17.21), which cleaves glutamate from the dipeptide N‐acetyl‐aspartyl‐glutamate (NAAG), on the conditioned place preference (CPP) response to cocaine in male rats. The i.p. administration of 15 mg/kg of cocaine produced a significant CPP response. The acquisition and expression of the CPP response to cocaine was blocked by the i.p. administration of 100 mg/kg of 2‐PMPA and the p.o. administration of 30 mg/kg of GPI 5693. In contrast, neither 2‐PMPA nor GPI 5693 produced a CPP or conditioned place aversion response when administered alone. Furthermore, neither 2‐PMPA or GPI 5693 altered the expression of the CPP response to food. These results indicate that NAALADase inhibitors block the incentive motivational value of cocaine, suggesting that such agents may be of use in treating cue‐induced craving in cocaine addicts. Synapse 41:22–28, 2001. © 2001 Wiley‐Liss, Inc.
Drift design of steel‐frame shear‐wall systems for tall buildings
Authors: Park Hyo Seon , Hong Kappyo , Seo Ji Hyun 
Published: August 2002

AbstractDrift design methods based on resizing algorithms are presented to control lateral displacements of steel‐frame shear‐wall systems for tall buildings. Three algorithms for resizing of structural members of the steel‐frame shear‐wall systems are derived by formulating the drift design process into an optimization problem that minimizes lateral displacement of the system without changing the weight of a structure. During the drift design process, cost‐effective displacement participation factors obtained by the energy method are used to determine the amount of material to be modified instead of calculating sensitivity coefficients. The overall structural design model with the drift design method for the steel‐frame shear‐wall systems is proposed and applied to the structural design of three examples. As demonstrated in the examples, the lateral displacement and interstorey drift of a frame shear‐wall system can be effectively designed by the drift design method without the time‐consuming trial‐and‐error process. Copyright © 2002 John Wiley & Sons, Ltd.
Teaching science problem solving: An overview of experimental work
Authors: Taconis R. , Ferguson‐Hessler M.G.M. , Broekkamp H. 
Published: August 2002

AbstractThe traditional approach to teaching science problem solving is having the students work individually on a large number of problems. This approach has long been overtaken by research suggesting and testing other methods, which are expected to be more effective. To get an overview of the characteristics of good and innovative problem‐solving teaching strategies, we performed an analysis of a number of articles published between 1985 and 1995 in high‐standard international journals, describing experimental research into the effectiveness of a wide variety of teaching strategies for science problem solving. To characterize the teaching strategies found, we used a model of the capacities needed for effective science problem solving, composed of a knowledge base and a skills base. The relations between the cognitive capacities required by the experimental or control treatments and those of the model were specified and used as independent variables. Other independent variables were learning conditions such as feedback and group work. As a dependent variable we used standardized learning effects. We identified 22 articles describing 40 experiments that met the standards we deemed necessary for a meta‐analysis. These experiments were analyzed both with quantitative (correlational) methods and with a systematic qualitative method. A few of the independent variables were found to characterize effective strategies for teaching science problem solving. Effective treatments all gave attention to the structure and function (the schemata) of the knowledge base, whereas attention to knowledge of strategy and the practice of problem solving turned out to have little effect. As for learning conditions, both providing the learners with guidelines and criteria they can use in judging their own problem‐solving process and products, and providing immediate feedback to them were found to be important prerequisites for the acquisition of problem‐solving skills. Group work did not lead to positive effects unless combined with other variables, such as guidelines and feedback. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 442–468, 2001
Further evidence for the role of free radicals in the limb teratogenicity of L‐NAME
Authors: Fantel Alan G. , Person Richard E. 
Published: August 2002

AbstractBackgroundL‐NAME (NG‐nitro‐L‐arginine methyl ester), a nitric oxide synthase inhibitor, causes severe limb reduction malformations when gravid rats are treated intraperitoneally on gd‐17. Hemorrhages, appearing within hours of L‐NAME administration, and defects at term can be significantly reduced by co‐treatment with PBN (α‐phenyl‐N‐t‐butylnitrone), a spin trap antioxidant. We have proposed that limb defects result from ischemia‐reperfusion injury. We examine the role of xanthine oxidase and ROS formation in the limb effects of L‐NAME.MethodsGravidas were treated with L‐NAME (50 mg/kg) in the presence or absence of allopurinol, a xanthine oxidase inhibitor. Spatial patterns of limb hemorrhage were determined promptly and at term as was digit length at the latter interval. Xanthine oxidase activities were assayed in control and treated limbs with and without allopurinol co‐treatment.ResultsAllopurinol significantly reduced hemorrhage severity in a dose‐responsive fashion when fetuses were examined at term. Higher doses of allopurinol significantly preserved digit length. Xanthine oxidase activities in fetal limb were significantly increased by L‐NAME treatment whereas co‐treatment with allopurinol restored activities to near‐control levels.ConclusionsThese findings support the role of excess reactive oxygen species (ROS) formation in L‐NAME‐induced limb reduction. We propose that nitric oxide (NO) depletion by L‐NAME interferes with vascular integrity, and causes vasoconstriction. Resultant hypoxia stimulates superoxide formation and nitric oxide formation catalyzed by the inducible isoform of nitric oxide synthase. The reduction products of superoxide or the products of its reaction with nitric oxide oxidize or nitrate endothelial components resulting in limb reduction defects. Teratology 66:24–32, 2002. © 2002 Wiley‐Liss, Inc.
E‐business model design, classification, and measurements
Authors: Dubosson‐Torbay Magali , Osterwalder Alexander , Pigneur Yves 
Published: August 2002

Abstract“Business model” is one of the latest buzzwords in the Internet and electronic business world.
This article has the ambition to give this term a more rigorous content. The objective is threefold. The first
objective is to propose a theoretical e‐business model framework for doing business in the Internet era.
The second is to propose a multidimensional classification‐scheme for e‐Business Models, as opposed
to the actual tendency in academic literature to use two‐dimensional classifications. The final objective
is to define critical success factors, based on a field study in order to find out and compare the performance
indicators used by e‐business firms that are competing with similar business models. © 2002 John
Wiley & Sons, Inc.
Toxicology of a Microcystis ichthyoblabe waterbloom from Lake Oued Mellah (Morocco)
Authors: Sabour Brahim , Loudiki Mohammed , Oudra Brahim , Vasconcelos Vitor , Martins Rosario , Oubraim Said , Fawzi Brahim 
Published: August 2002

AbstractIn the Lake Oued Mellah cyanobacteria waterblooms occur periodically in late spring and summer with Microcystis ichthyoblabe as the main bloom‐forming species. In 1999, a heavy waterbloom of M. ichthyoblabe occurred during May June with a maximal biomass of 298 mg/l. During this period, several bloom samples were collected. The toxicity assessment was done by mouse and brine shrimp (Artemia) bioassays. Apart from the sample collected on 15/06/1999, all the other samples were toxic by mouse bioassay. The LD50 determined by intraperitoneal injection to mice during active cyanobacterial growth and decline phases were 518 and 1924 mgDW/kg respectively. Using Artemia bioassay, the 24hLC50 varied from 6.0 to 40.6 mg/ml and the 48hLC50 ranged from 2.8 to 18.2 mg/ml. The separation and identification of microcystin variants was performed by high performance liquid chromatography–photodiode array detection. Eleven toxins were separated and preliminarily identified as microcystin variants as they exhibit a typical UV spectra like the microcystin‐LR standard. The quantification of total microcystins determined by enzyme‐linked immunosorbent assay showed that the contents were varied between 0.1 and 0.76 μg/g DW. © 2002 by Wiley Periodicals, Inc. Environ Toxicol 17: 24–31, 2002
Inhibition of sulfate‐reducing bacteria by metal sulfide formation in bioremediation of acid mine drainage
Authors: Utgikar Vivek P. , Harmon Stephen M. , Chaudhary Navendu , Tabak Henry H. , Govind Rakesh , Haines John R. 
Published: August 2002

AbstractAcid mine drainage (AMD) containing high concentrations of sulfate and heavy metal ions can be treated by biological sulfate reduction. It has been reported that the effect of heavy metals on sulfate‐reducing bacteria (SRB) can be stimulatory at lower concentrations and toxic/inhibitory at higher concentrations. The quantification of the toxic/inhibitory effect of dissolved heavy metals is critical for the design and operation of an effective AMD bioremediation process. Serum bottle and batch reactor studies on metal toxicity to SRB indicate that insoluble metal sulfides can inhibit the SRB activity as well. The mechanism of inhibition is postulated to be external to the bacterial cell. The experimental data indicate that the metal sulfides formed due to the reaction between the dissolved metal and biogenic sulfide act as barriers preventing the access of the reactants (sulfate, organic matter) to the necessary enzymes. Scanning electron micrographs of the SRB cultures exposed to copper and zinc provide supporting evidence for this hypothesis. The SRB cultures retained their ability to effect sulfate reduction indicating that the metal sulfides were not lethally toxic to the SRB. This phenomenon of metal sulfide inhibition of the SRB has to be taken into account while designing a sulfate‐reducing bioreator, and subsequently an efficient biotreatment strategy for AMD. Any metal sulfide formed in the bioreactor needs to be removed immediately from the system to maintain the efficiency of the process of sulfate reduction. © 2002 by Wiley Periodicals, Inc. Environ Toxicol 17: 40–48, 2002