bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and properties of poly(carbonate‐co‐ester)s obtained by cationic ring‐opening copolymerization of spiroorthocarbonate and ε‐caprolactone
Authors: Nagai Daisuke , Nishida Masaki , Ochiai Bungo , Endo Takeshi 
Published: March 2006

AbstractCationic ring‐opening copolymerization behavior of 1,5,7,11‐tetraoxaspiro[5.5]undecane (SOC1) and ε‐caprolactone (CL), and the thermal behavior of the obtained copolymers are described. When SOC1 and CL were cationically copolymerized under various feed ratios using BF3OEt2 as the initiator in CH2Cl2 at 25 °C, the corresponding copolymers were obtained in 77–99% yields. The 1H NMR spectroscopic analysis of the copolymers revealed that the copolymer compositions were almost identical to the feed ratios, and the diad ratios of SOC1–SOC1/SOC1–CL and CL–SOC1/CL–CL are 48.0/52.0 and 54.3/45.7. These observations proved the random structures of the copolymers without containing the long blocks of the homopolymer sequences. Differential scanning calorimetric (DSC) analysis revealed that the melting points and melting entharpies decreased with the increase of the SOC1 unit compositions, suggesting that the copolymers gain flexibility as the SOC1 unit increases. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2937–2942, 2006
Single electron transfer–degenerative chain transfer living radical polymerization of N‐butyl acrylate catalyzed by Na2S2O4 in water media
Authors: Coelho Jorge F. J. , Silva Ana M. F. P. , Popov Anatoliy V. , Percec Virgil , Abreu Mariana V. , Gonçalves Pedro M. O. F , Gil M. H. 
Published: March 2006

AbstractLiving radical polymerization of n‐butyl acrylate was achieved by single electron transfer/degenerative‐chain transfer mediated living radical polymerization in water catalyzed by sodium dithionate. The plots of number–average molecular weight versus conversion and ln[M]0/[M] versus time are linear, indicating a controlled polymerization. This methodology leads to the preparation of α,ω‐di(iodo) poly (butyl acrylate) (α,ω‐di(iodo)PBA) macroinitiators. The influence of polymerization degree ([monomer]/[initiator]), amount of catalyst, concentration of suspending agents and temperature were studied. The molecular weight distributions were determined using a combination of three detectors (TriSEC): right‐angle light scattering (RALLS), a differential viscometer (DV), and refractive index (RI). The methodology studied in this work represents a possible route to prepare well‐tailored macromolecules made of butyl acrylate in an environmental friendly reaction medium. Moreover, such materials can be subsequently functionalized leading to the formation of different block copolymers of composition ABA. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2809–2825, 2006
Interface optical phonons in spherical multilayer nanostructures
Authors: López I. , Kanyinda‐Malu C. , de la Cruz R. M. 
Published: March 2006

AbstractWithin the dielectric continuum model, we calculate the interface phonons in multilayered spherical nanostructures. The effect of the alloying in the shell material, together with the change in the embedding medium are also analyzed. In all investigated heterostructures, the interface characteristics experiment a constantlike tendency at critical geometrical parameter g c, whose values are sensitively determined by the ratio between dielectric constants of constitutive materials. We observe that the asymptotic limiting interface frequencies slightly depend on the embedding medium. For special cases, the high‐index phonon branches cross each other for specific values of geometrical parameter g . This crossing‐over critically depends on the core‐to‐shell dielectric constants ratio and on the type of host material. Also, we observe that the presence of Ga‐impurity in the shell material makes the highest shell‐like modes independent both on the geometrical parameter g and on the orbital index l . (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth studies, TEM and XRD investigations of iron‐filled carbon nanotubes
Authors: Müller C. , Golberg D. , Leonhardt A. , Hampel S. , Büchner B. 
Published: March 2006

AbstractThe formation mechanism of iron filled carbon nanotubes on oxidized silicon substrates precoated with thin metal layers (Fe, Co) has been studied. These filled structures were aligned perpendicular to the substrate surface. The nanotubes were produced by the thermal decomposition of ferrocene in an argon flow. We have studied the nanotube morphology and geometry (diameter, length) in detail. Transmission electron microscopy (TEM), X‐ray diffraction (XRD) and selected area electron diffraction (SAED) were used to analyze the iron nanorods inside the nanotubes. These investigations have revealed a majority fraction of α‐Fe and small amounts of γ‐Fe and Fe3C. Moreover only single crystalline iron was found. In summary we conclude that iron filled carbon nanotubes with this CVD route are formed via an open‐ended, base growth mechanism. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of MK‐0431 in human plasma using high turbulence liquid chromatography online extraction and tandem mass spectrometry
Authors: Zeng Wei , Musson Donald G. , Fisher Alison L. , Wang Amy Qiu 
Published: March 2006

AbstractA robust and sensitive method using high turbulence liquid chromatography (HTLC) online extraction with tandem mass spectrometry (MS/MS) for the determination of MK‐0431 in human plasma was developed and validated to support the clinical studies. This HTLC online extraction method eliminated the time‐consuming offline sample extraction procedures and significantly increased productivity. A narrow bore large particle size reversed‐phase column (Cyclone, 50 × 1.0 mm, 60 µm) and a BDS Hypersil C18 column (30 × 2.1 mm, 3 µm) were used as extraction and analytical columns, respectively. The linear dynamic range of the calibration curve was 0.5 to 1000 ng/mL. Intraday validation was conducted using five calibration curves prepared in five lots of human control plasma, and the intraday precision (RSD%) was from 2.4 to 9.0% and the accuracy was from 98.0 to 103% of the nominal value. The intraday precision (RSD%, n = 5) for plasma quality control (QC) samples varied from 2.0 to 5.3% and accuracy from 103 to 105% of the nominal value. The interday precision (RSD%) for 100 sets of plasma QC samples in 29 analytical runs varied from 6.3 to 9.0% and the accuracy from 98.8 to 104% of the nominal value. No significant difference was observed between the interday and intraday precision and accuracy of the QC samples. Copyright © 2006 John Wiley & Sons, Ltd.
Bilirubin degradation by uncoupled cytochrome P450. Comparison with a chemical oxidation system and characterization of the products by high‐performance liquid chromatography/electrospray ionization mass spectrometry
Authors: De Matteis Francesco , Lord Gwyn A. , Kee Lim Chang , Pons Nicoletta 
Published: March 2006

AbstractBilirubin is a protective antioxidant; however, when its conjugation and excretion are impaired, as in neonatal and hereditary jaundice, bilirubin accumulates and may cause severe neurotoxicity. Degradation of bilirubin takes place (a) on interaction with oxidative free radicals and (b) when cytochrome P450 (CYP) enzymes are uncoupled by polyhalogenated substrate analogues. The products of pathways (a) and (b) above have now been characterized by high‐performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI‐MS) and the mechanisms of fragmentation in part clarified. Oxidation of bilirubin by uncoupled CYP1A5 and by a Fe‐EDTA/H2O2 system produced both biliverdin and an identical profile of dipyrrolic fragments, as detected by positive ESI‐MS. A similar profile of oxidation products was found from mesobilirubin, all showing the expected increase in mass, thus providing direct evidence for fragmentation at the central methene bridge of the tetrapyrroles. Two degradation products, also detected by negative ESI‐MS, were characterized as dipyrroles retaining the central bridge carbon, with one or two oxygen atom(s) bound (probably as the aldehyde and hydroperoxide derivatives). Ions compatible with propentdyopents and bilifuscins were also detected, but here the assignment was less certain. It is concluded that the first step in the oxidation of bilirubin may be hydrogen abstraction at the central methene bridge. This is followed either by loss of another hydrogen to give biliverdin, or by oxygen binding and fragmentation. Fe‐EDTA/H2O2 and uncoupled CYP(FeO) may both initiate the reaction, the latter in an attempt to reduce the ferryl oxygen to water. These studies shed light on the CYP uncoupling mechanism and are of potential significance for the therapy of severe jaundice. Copyright © 2006 John Wiley & Sons, Ltd.
Matrix‐suppressed laser desorption/ionisation mass spectrometry and its suitability for metabolome analyses
Authors: Vaidyanathan Seetharaman , Gaskell Simon , Goodacre Royston 
Published: March 2006

AbstractMatrix‐assisted laser desorption/ionisation (MALDI) mass spectrometry was investigated for the simultaneous detection of several metabolites, as applicable to global metabolite analysis (metabolomics). The commonly employed organic matrices α‐cyano‐4‐hydroxycinnamic acid and 3,5‐dihydroxybenzoic acid, in both the crystalline and ionic liquid forms, were investigated. The employment of a low matrix‐to‐analyte molar ratio suppressed matrix peaks and was effective in detecting all the metabolites with a unique mass in a 30‐metabolite synthetic cocktail, albeit to varying degrees. These matrix‐suppressed laser desorption/ionisation (MSLDI) analyses were performed in the positive ion mode, and metabolites were detected as the protonated [M+H]+, sodiated [M+Na]+ or potassiated [M+K]+ species. The spectral signals were dominated by basic metabolites. It was possible to detect components of a synthetic cocktail when it was spiked quantitatively into a microbial extract, demonstrating the feasibility of using the technique for detecting metabolite signals in a complex biological matrix. However, analyte suppression effects were noted when the relative proportion of one analyte was allowed to increasingly dominate the others in a mixture. The implications of the findings with respect to applications in metabolomic investigations are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
A comparison of denominator degrees of freedom methods for multiple observer ROC analysis
Authors: Hillis Stephen L. 
Published: March 2006

AbstractThere are several methods available for analysing multireader ROC studies that generalize results to both the reader and case populations. Two of these methods—the Dorfman–Berbaum–Metz (DBM) method and the Obuchowki–Rockette (OR) method—appear to be quite different in their original formulations. However, recently it has been shown that the DBM and OR procedures yield the same test statistic when based on the same accuracy measure and covariance estimation method, but inferences can vary depending on which denominator degrees of freedom (ddf) method, DBM or OR, is used. I show in simulations that there are problems with both ddf methods: OR is ultraconservative with significance levels considerably below the nominal level, and DBM can result in extremely wide confidence intervals because the ddf can be close to zero. I propose a new ddf method that overcomes both of these problems and can be used with either the OR or DBM procedure. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of interval‐censored data from circular migrant and non‐migrant sexual partnerships using the EM algorithm
Authors: Zuma K. , Lurie M. , Jorgensen M. 
Published: March 2006

AbstractIn epidemiological studies where subjects are seen periodically on follow‐up visits, interval‐censored data occur naturally. The exact time the change of state (such as HIV seroconversion) occurs is not known exactly, only that it occurred sometime within a specific time interval. Methods of estimation for interval‐censored data are readily available when data are independent. However, methods for correlated interval‐censored data are not well developed. This paper considers an approach for estimating the parameters when data are interval‐censored and correlated within sexual partnerships. We consider the exact event times for interval‐censored observations as unobserved data, only known to be between two time points. Dependency induced by sexual partnerships is modelled as frailties assuming a gamma distribution for frailties and an exponential distribution on the time to infection. This formulation facilitates application of the expectation‐maximization (EM) algorithm. Maximization process maximizes the standard survival frailty model. Results show high degree of heterogeneity between sexual partnerships. Intervention strategies aimed at combating the spread of HIV and other sexually transmitted infections (STI)s should treat sexual partnerships as social units and fully incorporate the effects of migration in their strategies. Copyright © 2006 John Wiley & Sons, Ltd.
Monitoring the introduction of a surgical intervention with long‐term consequences
Authors: Gorst‐Rasmussen A. , Spiegelhalter D. J. , Bull C. 
Published: March 2006

AbstractSurgical innovations are often introduced for their expected long‐term benefits, but the decision to abandon the existing treatment must be based on the available short‐term data and rational judgment. We present a framework for monitoring the introduction of a surgical intervention with long‐term consequences and failure‐time endpoints. The framework is based on Bayesian methods, and formally combines study data, clinical opinion, and external evidence to construct a posterior survival function from which intuitive summary statistics can be extracted to aid decision making. It incorporates learning effects and is adaptable to a wide variety of settings. The methods are illustrated on survival data from a cohort of 325 consecutive neonates treated for simple transposition of the great arteries with either the Senning or the Switch operation during the period 1978–1998. Copyright © 2006 John Wiley & Sons, Ltd.
Log‐linear non‐uniform association models for agreement between two ratings on an ordinal scale
Authors: Valet Fabien , Guinot Christiane , Mary Jean Yves 
Published: March 2006

AbstractIn agreement studies, when objects are rated independently by two raters (or twice by the same rater), an association between their ratings on two categories arises, reflecting the distinguishability of these two categories for these raters. When ratings are performed on an ordinal scale, this association between ratings on two categories increases when the distance between these categories increases on the ordinal scale. Goodman's log‐linear models derived for the analysis of agreement between two raters on an ordinal scale assume that distinguishabilities between adjacent categories are either constant, ora priorifixed. Log‐non‐linear models that allow variations of the distinguishabilities between adjacent categories along the scale, may lead to difficulties in parameter estimation.This paper describes a new class of log‐linear non‐uniform association models. These models extend the log‐linear uniform association model by allowing variations of distinguishability between adjacent categories (along the scale). These new models are used to analyse ordinal agreement between dermatologists when assessing the severity of different cutaneous signs of ageing on women faces. Copyright © 2006 John Wiley & Sons, Ltd.
Acoustic diffraction by a pair of poroelastic cylinders
Authors: Hasheminejad S.M. , Avazmohammadi R. 
Published: March 2006

AbstractThis study treats the interaction of a plane compressional sound wave with a cluster of two fluid‐saturated porous elastic cylinders submerged in an unbounded acoustic medium. The novel features of Biot dynamic model for description of poroelastic material behaviour along with the appropriate wave field expansions, the pertinent boundary conditions, and the translational addition theorem for cylindrical wave functions are employed to develop a closed‐form solution in the form of infinite series. The theoretical model was extended to consider the case of sound diffraction by a pair of absorbing cylinders with locally reacting or extended reaction boundaries. The analytical results are illustrated with numerical examples in which two identical air‐saturated glass wool cylinders are insonified by a plane sound wave at end‐on/broadside incidence. The most fundamental acoustic field quantity, namely, the scattering form function amplitude is evaluated and discussed for representative values of the parameters characterizing the system. The effects of incident wave frequency, angle of incidence, and proximity of the two cylinders are examined. Particular attention has been focused on multiple scattering interactions as well as the surface reaction modelling effects. Numerical comparison is made with the case of acoustic diffraction by a pair of absorbing cylinders with locally reacting or extended reaction boundaries. Limiting cases involving two rigid cylinders and also a pair of penetrable (fluid) cylinders are considered and good agreements with well‐known solutions are established.
Variation in nature: its implications for zoo elephant management
Authors: Hutchins Michael 
Published: March 2006

AbstractDespite many advances in animal care and welfare over the past few decades, zoos have been criticized recently for the quality of their elephant management programs. More specifically, critics have argued that elephants live miserable lives in captivity and thus should not be kept in zoos. Poor health and reproductive success, they say, are the result of the combined impact of: a lack of exercise; exposure to cold temperatures and disease; and stress due to the use of “brutal” training techniques, chaining and inappropriate social environments. Everyone, including zoo professionals, seems to agree that improvements in zoo elephant management are necessary and appropriate. However, there is considerable disagreement on how to proceed and little information on which to base such decisions. One tactic that the critics have adopted in their efforts to promote change is their frequent reference to “nature” as a yardstick for gauging the adequacy of zoo animal management and care. An argument is made that direct zoo–wild comparisons are of questionable utility and may be invalid from a scientific perspective. Some critics talk about “nature” as if it represented a fixed set of rules by which captive managers must either abide by or risk diminishing the health and welfare of their charges. However, many aspects of elephant natural history vary greatly depending on prevailing environmental conditions and elephants may be much more flexible than many critics are giving them credit for. Thus, although zoo animal managers should look to nature for clues about how to best care for captive elephants, they should not feel constrained by them. This revelation is not intended as an excuse for poor elephant management or to support the status quo. On the contrary, a better approach is to develop realistic and biologically meaningful metrics that reflect the quality of elephant care and welfare and to use them to measure the success of evolving zoo elephant programs. Zoo Biol 25:161–171, 2006. © 2006 Wiley‐Liss, Inc.
Histidinaemia. Part II: Impact; a retrospective study
Authors: Rosenmann A. , Scriver C. R. , Clow C. L. , Levy H. L. 
Published: March 2006

AbstractForty‐two articles published between 1961 and 1977 describing 43 probands and 26 siblings with histidinaemia were used for the retrospective study. Our objective was to describe the apparent impact of the mutation on development and health in human histidinaemia. The findings were similar to those of an earlier survey (Popkinet al., 1974). Most probands (79 %) had a disadaptive CNS phenotype (mental retardation, impaired speech, seizures, aberrant behaviour, and/or learning disorder); half the histidinaemic siblings had a similar phenotype. The modal IQ score was 70; age at recognition of symptoms (CNS phenotype) varied from 1 month to 16 y (modal age 2½ y). There was no correlation between blood histidine (reported values) and occurrence of severity of CNS phenotype. Thirty per cent of histidinaemia subjects, for whom the perinatal history was described, had an abnormal experience. Reported cases with the CNS phenotype apparently represent a very small fraction (about 1 %) of all subjects with histidinaemia; this implies that the histidinaemia phenotype is not disadaptive in man.
Histidinaemia. Part III: Impact; a prospective study
Authors: Coulombe J. T. , Kammerer B. L. , Levy H. L. , Hirsch B. Z. , Scriver C. R. 
Published: March 2006

AbstractWe describe a prospective study of histidinaemia. Probands and siblings (n = 21) with typical histidinaemia in 16 families were ascertained by newborn screening; diagnosis was confirmed by appropriate investigations in each subject; none had been treated by low histidine diet. The median age of subjects with histidinaemia was 9.5 y (mean 10.0, SD 3.5, range 6‐18). Age‐matched sib‐pairs and their mothers were studied. IQ scores (Full Scale, Verbal and Performance Scores), Visual‐Motor Integration Performance (Bender Gestalt and Koppitz scores), Wide Range Achievement Test (Reading and Mathematics), school performance, and psychological history were evaluated, as well as the medical history (pregnancy, delivery, neonatal, post‐natal development). Findings were correlated with biochemical phenotype. CNS development in histidinaemic subjects (mean and distribution of scores) was normal; outlier values did not correlate with degree of histidinaemia. We can conclude that histidinaemia detected by newborn screening is a non‐disadaptive phenotype.
A clinical trial of fibroblast transplantation for the treatment of mucopolysaccharidoses
Authors: Gibbs D. A. , Spellacy E. , Tompkins R. , Watts R. W. E. , Mowbray J. F. 
Published: March 2006

AbstractThis paper reports the clinical and biochemical results in six patients with Hurler disease (Mucopolysaccharidosis IH; McKusick 25280), two patients with Hunter disease (Mucopolysaccharidosis II; McKusick 25285) and one patient with Sanfilippo B disease (Mucopolysaccharidosis IIIB; McKusick 25292) who were treated by fibroblast transplantation. Except for one patient who died for a coincidental reason, the patients have been studied for between 2.5 and 4.5 years. The clinical course of the disease was not materially altered. There was no evidence that the patients had developed immune responses against the transplanted fibroblasts. Transplantation did not produce measurable levels of either α‐l‐iduronidase (EC 3.2.1.76) in the leukocytes from patients with Hurler disease or ofN‐acetyl‐α‐d‐glucosaminidase (EC 3.2.1.50) in the plasma of the patient with Sanfilippo B disease. Under the conditions used for the assay, leukocytes from the patients with Hunter disease had detectable levels of residual α‐l‐idurono‐2‐sulphate sulphatase activity which were increased after the transplants, although these changes were of inconstant size and their time course was not consistently related to the transplantations. Cytogenetic studies in cases where the donor was of the opposite sex detected only cells of the recipient's sex among the fibroblasts grown from biopsies of the transplantation sites. The technique used would have detected a donor to recipient cell ratio of 1:100. We found no consistent long‐term trends in the excretion patterns of glycosaminoglycans and oligosaccharides from either a quantitative or qualitative point of view which could be specifically related to the transplantation. The combined administration of immunosuppressive doses of prednisolone and azathioprine was associated with an increased excretion of the lower molecular weight glycosaminoglycans. We conclude that fibroblast transplantation is not therapeutically useful in the diseases studied.