bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of elongational properties of polymer melts for film blowing and thermoforming
Authors: Münstedt Helmut , Kurzbeck Stefan , Stange Jens 
Published: July 2006

AbstractTwo polyethylene and two polypropylene melts were characterized in uniaxial elongational flow. They exhibit significant differences with respect to strain hardening. For the polypropylenes it was shown that the elongational behavior found in uniaxial elongation is qualitatively reflected in biaxial deformation too. From the polyethylenes, films were blown using laboratory equipment, and the polypropylenes were processed into beakers by thermoforming. For both materials it could be shown that strain hardening is of advantage for the geometrical uniformity of the processed items. POLYM. ENG. SCI., 46: 1190–1195, 2006. © 2006 Society of Plastics Engineers
Correlations and predictions of solvent effects on reactivity: some limitations of multi‐parameter equations and comparisons with similarity models based on one solvent parameter
Authors: Bentley T. William , Garley Michael S. 
Published: July 2006

AbstractThree recent publications on multi‐parameter correlations of solvent effects on solvolytic reactivity are re‐examined, by considering ‘similarity’ and/or ‘analogy’. Systematic errors due to compensation effects and to comparisons between dissimilar processes are found. Models for solvent nucleophilicity involving dissimilar spectroscopic processes (e.g. β or B parameters) give insensitive measures of low nucleophilicity. From qualitative considerations based on structural similarities, it is predicted that the sensitivities to changes to solvent polarity for solvolyses of chloroalkanes should be in the order: 1‐adamantyl (3) > 2‐methyl‐2‐adamantyl (1) > t‐butyl (2). The predictions are confirmed quantitatively by simple linear free‐energy relationships and similarity models, involving correlations with YCl (based on solvolyses of 1‐chloroadamantane) or ET(30) (based on solvatochromism). Multi‐parameter correlations, indicating that solvolyses of 1 show a low sensitivity to both solvent polarity and electrophilicity, and also a negative sensitivity to solvent nucleophilicity, are shown to be unreliable. Large errors are also evident in recent KOMPH2 calculations. Conclusions are supported by comparing several multi‐parameter treatments of solvolyses of 4‐methoxyneophyl tosylate, for which there is a reliable set of kinetic data and a generally accepted mechanism. Copyright © 2006 John Wiley & Sons, Ltd.
TiO2‐sensitised photo‐oxidation mechanism of indane and some of its hetero‐analogues in deaerated CH3CN
Authors: Bettoni Marta , Giacco Tiziana Del , Rol Cesare , Sebastiani Giovanni V. 
Published: July 2006

AbstractA mechanistic study, principally based on product analysis, relative to the TiO2‐photosensitized oxidation of indane and some of its hetero‐analogues, in deaerated CH3CN and in the presence of Ag2SO4, was performed. In particular: (i) 1‐acetamidoindan (principal product), indene, 1‐indanol and 1‐indanone were obtained from indan; (ii) 5‐methoxyindan gave 6‐methoxyindene (principal product) and 5‐methoxy‐1‐indanone; (iii) 2,3‐dihydrobenzofuran, 2,3‐dihydroindole and 2,3‐dihydrobenzothiophene produced benzofuran, indole and benzothiophen (the last one accompanied by minor amounts of 2,3‐dihydrobenzothiophene‐1‐oxide), respectively. Considering the previous studies on photo‐oxidation of analogous substrates as benzylic derivatives (arenes, alcohols and ethers) and from reaction product profiles, an electron‐transfer mechanism (from the substrate to the photogenerated hole) is suggested, where the radical cation intermediate should deprotonate to a benzylic radical. The carbocation obtained from the oxidation of this radical should competitively evolve to alkene, alcohol and acetamide. H218O labelling photo‐oxidation experiments suggest that the ketone, when present, should derive from the substrate, through the alcohol as intermediate. Copyright © 2006 John Wiley & Sons, Ltd.
A dibasic acid with reversed order of the stepwise ionization constants: 2,7‐dichlorofluorescein in the ternary solvent mixture benzene–ethanol–water
Authors: Mchedlov‐Petrossyan Nikolay O. , Salamanova Natalya V. , Vodolazkaya Natalya A. , Gurina Yuliya A. , Borodenko Valentina I. 
Published: July 2006

AbstractThe ionization constants of 2,7‐dichlorofluorescein were determined and the molecular structures of the equilibrium forms were established in the ternary solvent system benzene–ethanol–water (mass ratio 47:47:6) by using visible spectroscopy. In this solvent mixture with relative dielectric constant εr = 12.8 and normalized Reichardt's parameter
E = 0.587, an inversion of the stepwise ionization constants of the dye, Ka1 and Ka2, occurs. The Ka1/Ka2 ratio changes from 16 in water and 4.8 in 50 mass % aqueous ethanol to 0.1 in the ternary solvent system with ionic strength of 0.002 mol dm−3, where pKa1 = 9.23 ± 0.08 and pKa2 = 8.22 ± 0.08 (25 °C). Such an extraordinary interrelation between the Ka constants is in line with the molecular structure of ionic and nonionic species of 2,7‐dichlorofluorescein deduced from their vis absorption spectra, as well as with the expressed salt effects and the probable ion association. The dianion R2− (5 in Scheme 1) possesses a band with λmax = 512 nm and a molar absorptivity of E = 84.3 × 103 cm−1 mol−1 dm3. The tautomeric equilibrium of the neutral form, H2R, is strongly shifted toward the colorless lactone (2 in Scheme 1). The (very intensive) absorption band of the HR− species singled out from the vis spectra at different acidity, is red‐shifted by Δλ ≈ 20 nm against the band of the dianion R2−. Hence, the monoanion HR− is found to be completely converted into the ‘phenolate’ tautomer 4 with groups COOH and O−, while in aqueous solutions the ‘carboxylate’ tautomer 3 with groups COO− and OH predominates. In 50 mass % aqueous ethanol, the two tautomers 3 and 4 exist in commensurable concentrations. Emission and fluorescence excitation spectra and fluorescence quantum yield of the dianion R2− in the ternary solvent mixture were determined. Copyright © 2006 John Wiley & Sons, Ltd.
Conformational analysis, Part 41. A modelling and LIS/NMR investigation of the conformations of α,β‐unsaturated carbonyl compounds
Authors: Abraham Raymond J. , Mobli Mehdi , Ratti Joyce , Sancassan Fernando , Smith Timothy A. D. 
Published: July 2006

AbstractA novel Lanthanide Induced Shift Analysis (LISA) is presented. In this analysis both the paramagnetic and the diamagnetic lanthanide induced chemical shifts are normalised separately in contrast to previous techniques in which only the paramagnetic shifts were normalised. This procedure is used together with molecular mechanics (MMFF94) and ab initio (RHF/6‐31G, RHF/6‐311G** and B3LYP/6‐311G**) calculations to investigate s‐cis/s‐trans isomerism in some α,β‐unsaturated aldehydes, ketones and esters. In tiglic aldehyde 1 and trans‐cinnamaldehyde 4 the s‐trans conformer predominates with energy differences ΔE (s‐cis–s‐trans) of 1.64 and 1.76 kcal/mol. In methyl vinyl ketone 2 and trans‐cinnamyl methyl ketone 5 the populations of the s‐cis and s‐trans isomers are almost equal (ΔE 0.24 and 0.0 kcal/mol) and in methyl crotonate 3 and methyl trans‐cinnamate 6 the s‐cis conformer is more stable (ΔE −0.72 and −0.41 kcal/mol). These results are in agreement with both the MMFF94 and ab initio calculated energies for the compounds except tiglic aldehyde 1 in which all the calculated values are too large and cinnamyl ketone 5. In this compound the ab initio calculations predict the s‐cis form to be more stable than the s‐trans in contrast to both the MM calculations and the observed result which give both forms of equal energy. Also in both the MM and ab initio calculations phenyl substitution in the ketone (2 vs. 5) considerably stabilises the s‐cis form. This is not observed in practise. In phenyl acetate 7 the B3LYP calculations give two equally stable structures, one planar one non‐planar. The MMFF94 and MP2 calculations and the LIS analysis support the existence of only the non‐planar conformer in solution, which is also the conformation of phenyl acetate in the crystal. Copyright © 2006 John Wiley & Sons, Ltd.
Complex amphiphilic networks derived from diamine‐terminated poly(ethylene glycol) and benzylic chloride‐functionalized hyperbranched fluoropolymers
Authors: Powell Kenya T. , Cheng Chong , Wooley Karen L. , Singh Anuradha , Urban Marek W. 
Published: July 2006

AbstractAmphiphilic copolymer networks were prepared from hyperbranched fluoropolymer (HBFP*, Mn = 38 kDa, by atom transfer radical‐self condensing vinyl copolymerization) and linear diamine‐terminated poly(ethylene glycol) (DA‐PEG, Mn = 1,630 Da). Model studies found that the crosslinking mechanism occurred at ambient temperature as a result of reaction between DA‐PEG and the benzylic chlorides of HBFP*. These networks underwent covalent attachment to glass microscope slides derivatized with 3‐aminopropyltriethoxysilane, whereupon gel percent studies at various weight percentages of DA‐PEG to HBFP* found that curing could be achieved at lower temperatures and shortened time periods relative to the previously reported parent HBFP–PEG system. Thermogravimetric analysis revealed that the crosslinked materials gave no evident mass loss up to 250 °C. Differential scanning calorimetry of the complex amphiphilic networks showed a suppressed glass transition temperature, relative to that observed for neat HBFP*, and multiple melting DA‐PEG endotherm(s) near 30 °C. The films possessed a topographically‐complex surface with features that increased in tandem with an increase in the ratio of DA‐PEG to HBFP*, as detected by atomic force microscopy and quantified by increased rms roughness values. Internal reflection infrared imaging revealed a heterogeneous surface composition and confirmed that the domain sizes increased as the weight percent of DA‐PEG increased. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4782–4794, 2006
Synthesis and characterization of new blue‐light‐emitting polymers based on PPP and PPV having fluorene pendant at vinyl bridge
Authors: Kim Yun‐Hi , Jung Sang‐Yun , Jung Sung Ouk , Park Moon‐Hak , Kwon Soon‐Ki 
Published: July 2006

AbstractThe new poly(arylene vinylene) derivatives, which are composed of biphenylene vinylene phenylene vinylene, biphenylene vinylene m‐phenylene vinylene, terphenylene vinylene phenylene vinylene, and terphenylene vinylene m‐phenylene vinylene as backbone and bulky fluorene pendants at each vinyl bridge, were designed, synthesized, and characterized. The obtained polymers showed weight‐average molecular weights of 11,100–39,800 with polydispersity indexes ranging from 1.5 to 2.1. The resulting polymers were amorphous with high thermal stability and readily soluble in common organic solvents. The obtained polymers showed blue emission (λmax = 456–475 nm) in PL spectra, and polymer 4 containing terphenylene vinylene m‐phenylene vinylene showed the most blue shifted blue emission (λmax = 456 nm). The double layer light‐emitting diode devices fabricated by using obtained polymers as emitter emitted bright blue light. The device showed turn on voltage around 6.5 V and brightness of 70–250 cd/m2. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4923–4931, 2006
Curing reaction of glycidylthioether resins: Kinetic model study by near infrared spectroscopy and multivariate curve resolution
Authors: Garrido M. , Larrechi M. S. , Rius F. X. , Ronda J. C. , Cádiz V. 
Published: July 2006

AbstractThe reactivity of sulfur‐based epoxy monomers was studied by monitoring of a model system involving phenylglycidylthioether and aniline. The reaction was carried out under isothermal conditions and monitored in situ by near infrared spectroscopy. Using multivariate curve resolution‐alternating least squares made it possible to obtain the concentration and spectral profiles of each species throughout the reaction. To obtain the kinetic rate constants, the values of the recovered concentration profiles were fitted to a kinetic model proposed for the reaction. Reactivity was evaluated by comparing the concentration profiles and kinetic rate constants obtained with the same parameters obtained for phenylglycidylether/aniline as a reference system. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4846–4856, 2006
Synthesis and light‐emitting properties of platinum‐containing oligoynes and polyynes derived from oligo(fluorenyleneethynylenesilylene)s
Authors: Wong Wai‐Yeung , Poon Suk‐Yue , Shi Jian‐Xin , Cheah Kok‐Wai 
Published: July 2006

AbstractA series of blue‐light‐emitting oligo(fluorenyleneethynylenesilylene)s (OFESs) of the general formula HCCRCC(ECCRCC)mECCRCCH (E = SiPh2, SiMe2, or SiMe2SiMe2; m = 0–2; R = 9,9‐dihexylfluorene‐2,7‐diyl) and their phosphorescent platinum‐containing oligoynes and polyynes were synthesized and characterized. The solution properties and regiochemical structures of this new structural class of organosilicon‐based polyplatinayne polymers {trans‐[Pt(PBu3)2C CRCC(ECCRCC)mECCRCC]n} were studied with IR and NMR (1H, 13C, 29Si, and 31P) spectroscopy. The optical absorption and photoluminescence spectra of these metallopolymers were examined and compared with their discrete oligomeric model complexes. Our studies led to a novel approach of using the sp3‐silyl moiety as a conjugation interrupter to limit the effective conjugation length in metal polyynes, which could boost the phosphorescence decay rates essential for light‐energy harvesting from the triplet excited state. The influence of the heavy platinum atom and the group 14 silyl unit possessing different side‐group substituents on the thermal and phosphorescence properties was investigated in detail. We also established the goal of studying the evolution of the lowest singlet and triplet excited states with chain length m of OFESs and the nature of E in these metallopolymers. This work indicated that the phosphorescence emission efficiency harnessed through the heavy‐atom effect of platinum in the main chain did not change very much with oligomer chain length m but generally decreased with the E group in the order SiMe2 > SiMe2SiMe2 > SiPh2. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4804–4824, 2006
EORTC QLQ‐INFO26: a questionnaire to assess information given to cancer patients a preliminary analysis in eight countries
Authors: Arraras Juan Ignacio , Kuljanic‐Vlasic Karin , Bjordal Kristin , Yun Young Ho , Efficace Fabio , Holzner Bernhard , Mills Judith , Greimel Elfriede , Krauss Oliver , Velikova Galina 
Published: July 2006

AbstractInformation disclosure is a key factor in the support for cancer patients. The European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Group has developed a questionnaire to evaluate the level of information received by cancer patients at different stages of their disease and treatment: the EORTC QLQ‐INFO26. It can be used in clinical practice and research, including clinical trials. The questionnaire was developed following EORTC Quality of Life Group guidelines. The paper presents the data on 133 patients from eight countries. The resulting EORTC QLQ‐INFO26 questionnaire includes four sub‐scales on information regarding their cancer, medical tests, treatment and other services and several single items. Copyright © 2006 John Wiley & Sons, Ltd.
Variability in initial spray deposit in apple trees in space and time
Authors: Xu Xiangming , Wu Pihong , Thorbek Pernille , Hyder Kieran 
Published: July 2006

AbstractVariation in pesticide residues in space and time has not been investigated systematically in spite of the large variability found at single scales (e.g. between trees or orchards). Information on variability at different scales will support the development of sampling methods and more reliable prediction of residues. Experiments were conducted to quantify the spatiotemporal variability in initial spray deposit on apple leaves and fruit using a substitute tracer (zinc EDTA chelate). Five hierarchical spatial scales were defined as (1) between orchards, (2) between plots within an orchard, (3) between trees within a plot, (4) between zones within a tree and (5) between leaves/fruit within a zone. Similarly, two temporal scales were defined as (1) between applications within a single year and (2) between years. The initial zinc concentration was approximately log‐normally distributed; the variability in initial deposit concentration was greater on leaves than on fruit. The average initial zinc deposition was significantly greater in the top and outside zones than in the middle zones within individual trees. The most important scale for driving residue variability is the within‐zone unit‐to‐unit variation, contributing to 71 and 49% of the observed variability for leaf and fruit samples respectively. Variability at other scales was related to the variation in the tree architecture. The results indicated that stratified sampling on the basis of within‐tree zone structures, with the effort focused on within‐zone sampling, should be used for the determination of pesticide residues. Copyright © 2006 Society of Chemical Industry
Enhancement of fungicidal and insecticidal activity by reductive alkylation of chitosan
Authors: Rabea Entsar I , Badawy Mohamed EI , Rogge Tina M , Stevens Christian V , Steurbaut Walter , Höfte Monica , Smagghe Guy 
Published: July 2006

AbstractA series of N‐alkyl chitosan (NAC) derivatives were synthesized using a reductive alkylation reaction to examine their fungicidal and insecticidal activity. The chemical structures were characterized by IR and 1H NMR spectroscopy, and the degree of substitution (DS) ranged from 0.02 to 0.37. Their fungicidal activity was evaluated against the grey mould Botrytis cinerea Pers ex Fr (Leotiales: Sclerotiniaceae) and the rice leaf blast pathogen Pyricularia grisea Sacc [Teleomorph: Magnaporthe grisea (Hebert) Barr] by a radial growth bioassay. It was of interest that most of the NAC derivatives were more active against both fungi than chitosan itself. The most active derivative was N‐(2,2‐diphenylethyl)chitosan with EC50 values of 0.031 and 0.23 g L−1 against B. cinerea and P. grisea respectively. In addition, some derivatives, at higher concentrations up to 1.0 g L−1, inhibited the mycelial growth and spore formation of P. grisea. Bioassays against larvae of the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) with the NAC derivatives at a rate of 5.0 g kg−1 in artificial diet demonstrated that N‐(3‐phenylbutyl)chitosan was the most active compound. In addition, N‐propylchitosan, N‐undecanylchitosan and N‐(3‐phenylpropyl)chitosan derivatives strongly inhibited larval weight gain in S. littoralis, with respective reductions of 76, 66 and 65% after 4 days of feeding on treated diet. Copyright © 2006 Society of Chemical Industry
Modeling of the Inhibition Constant (Ki) of Some Cruzain Ketone‐Based Inhibitors Using 2D Spatial Autocorrelation Vectors and Data‐Diverse Ensembles of Bayesian‐Regularized Genetic Neural Networks
Authors: Caballero Julio , Tundidor‐Camba Alain , Fernández Michael 
Published: July 2006

AbstractThe inhibition constant (Ki) of a set of 46 ketone‐based cruzain inhibitors against cysteine protease cruzain was successfully modeled by means of data‐diverse ensembles of Bayesian‐regularized genetic neural networks. 2D spatial autocorrelation vectors were used for encoding structural information yielding a nonlinear model describing about 90 and 75% of ensemble training and test set variances, respectively. From the results of a ranking analysis of the neural network inputs, it was derived that atomic van der Waals volume distributions at topological lags 3, 5, and 6 in the 2D topological structure of the inhibitors have a high nonlinear influence on the inhibition constants. Furthermore, optimum subset of autocorrelation vectors well mapped the studied compounds according to their inhibition constant values in a Kohonen self‐organizing map.
Performance assessment for radiologists interpreting screening mammography
Authors: Woodard D. B. , Gelfand A. E. , Barlow W. E. , Elmore J. G. 
Published: July 2006

AbstractWhen interpreting screening mammograms radiologists decide whether suspicious abnormalities exist that warrant the recall of the patient for further testing. Previous work has found significant differences in interpretation among radiologists; their false‐positive and false‐negative rates have been shown to vary widely. Performance assessments of individual radiologists have been mandated by the U.S. government, but concern exists about the adequacy of current assessment techniques.We use hierarchical modelling techniques to infer about interpretive performance of individual radiologists in screening mammography. While doing this we account for differences due to patient mix and radiologist attributes (for instance, years of experience or interpretive volume). We model at the mammogram level, and then use these models to assess radiologist performance. Our approach is demonstrated with data from mammography registries and radiologist surveys. For each mammogram, the registries record whether or not the woman was found to have breast cancer within one year of the mammogram; this criterion is used to determine whether the recall decision was correct.We model the false‐positive rate and the false‐negative rate separately using logistic regression on patient risk factors and radiologist random effects. The radiologist random effects are, in turn, regressed on radiologist attributes such as the number of years in practice.Using these Bayesian hierarchical models we examine several radiologist performance metrics. The first is the difference between the false‐positive or false‐negative rate of a particular radiologist and that of a hypothetical ‘standard’ radiologist with the same attributes and the same patient mix. A second metric predicts the performance of each radiologist on hypothetical mammography exams with particular combinations of patient risk factors (which we characterize as ‘typical’, ‘high‐risk’, or ‘low‐risk’). The second metric can be used to compare one radiologist to another, while the first metric addresses how the radiologist is performing compared to an appropriate standard. Interval estimates are given for the metrics, thereby addressing uncertainty.The particular novelty in our contribution is to estimate multiple performance rates (sensitivity and specificity). One can even estimate a continuum of performance rates such as a performance curve or ROC curve using our models and we describe how this may be done. In addition to assessing radiologists in the original data set, we also show how to infer about the performance of a new radiologist with new case mix, new outcome data, and new attributes without having to refit the model. Copyright © 2006 John Wiley & Sons, Ltd.
Individualizing drug dosage by using a random intercept linear model
Authors: Diaz Francisco J. , Rivera Tulia E. , Josiassen Richard C. , Leon Jose de 
Published: July 2006

AbstractAn algorithm for drug dosage individualization is proposed. The algorithm assumes a random intercept linear model for the log of trough‐plasma‐concentration‐to‐dosage ratio of the drug at steady‐state, and aims at determining an optimum dosage for producing a trough steady‐state plasma concentration within a target concentration range. The minimum number of algorithm steps necessary to find the optimum dosage is computed. Computations are illustrated for clozapine, an antipsychotic drug used to treat patients with severe schizophrenia. Copyright © 2006 John Wiley & Sons, Ltd.