bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of (S)‐cyano(3‐phenoxyphenyl)methyl (1R,3R)‐ 3‐[(1Z)‐2‐chloro‐3,3,3‐trifluoro‐1‐propenyl]‐2,2‐dimethylcyclopropanecarboxylate‐1‐14C
Authors: Johnson Peter L. 
Published: January 2007

Abstractγ‐Cyhalothrin (1a), (S)‐cyano(3‐phenoxyphenyl)methyl (1R,3R)‐3‐[(1Z)‐2‐chloro‐3,3,3‐trifluoro‐1‐propenyl]‐2,2‐dimethylcyclopropanecarboxylate, is a single‐isomer, synthetic pyrethroid insecticide marketed by Pytech Chemicals GmbH, a joint venture between Dow AgroSciences and Cheminova A/S. As a part of the registration process there was a need to incorporate a carbon‐14 label into the cyclopropyl ring of this molecule. A high yielding radiochemical synthesis of γ‐cyhalothrin was developed from readily available carbon‐14 labeled N‐t‐Boc protected glycine. This seven step synthesis, followed by a preparative normal phase HPLC separation of diastereomers, provided 21.8 mCi of γ‐cyhalothrin‐1‐14C (1b) with >98% radiochemical purity. Copyright © 2007 John Wiley & Sons, Ltd.
Improved method to quantify intracellular zidovudine mono‐ and triphosphate in peripheral blood mononuclear cells by liquid chromatography‐tandem mass spectrometry
Authors: Compain Séverine , Durand‐Gasselin Lucie , Grassi Jacques , Benech Henri 
Published: January 2007

AbstractThe determination of intracellular triphosphate metabolites of nucleoside analogs used in anti‐HIV therapy is very challenging. Despite the well‐known sensitivity and selectivity of LC‐MS/MS, the measurement of the triphosphate metabolite of zidovudine (AZT‐TP) remains difficult because of the interferences induced by endogenous nucleotides triphosphates.We describe a new approach that allows improved determination of AZT‐TP simultaneously with AZT‐monophosphate (MP). This was obtained, first, by monitoring a transition from the molecular ion of AZT‐TP to a minor but very specific product ion. Then, the spiking of samples with a constant amount of AZT‐TP allowed the signal to emerge from background, leading to increased sensitivity. Finally, the analytical run time was reduced to less than 10 min. The low limits of quantification were at 150 and 300 fmol per sample for AZT‐TP and AZT‐MP, respectively. Recoveries were higher than 85%. Inaccuracy and precision were lower than 10% and 15% (17% at the limit of quantification), respectively.The new method offers the possibility of determining simultaneously other nucleotide phosphates, as shown here for d4T‐TP (the triphosphate metabolite of another nucleoside analog, stavudine or d4T) and 2′‐deoxythymidine‐5′‐triphosphate or dTTP (the corresponding natural nucleotide triphosphate). Copyright © 2007 John Wiley & Sons, Ltd.
Inter‐individual variability in the expression of the mutated form of hPS1M146L determined the production of Aβ peptides in the PS1xAPP transgenic mice
Authors: Caballero Cristina , Jimenez Sebastian , Moreno‐Gonzalez Ines , Baglietto‐Vargas David , Sanchez‐Varo Raquel , Gavilan M. Paz , Ramos Blanca , del Rio Juan Carlos , Vizuete Marisa , Gutierrez Antonia , Ruano Diego , Vitorica Javier 
Published: January 2007

AbstractThe detection of the early phenotypic modifications of Alzheimer's disease (AD) models is fundamental to understand the progression and identify pharmacologic targets of this pathology. However, a large variability within different models and between age‐matched mice from the same model has been observed. This variability could be due to heterogeneity in the Aβ production. Present results showed the existence of a large variability in the Aβ deposition in both hippocampus and cortex in 6‐month‐old PS1xAPP mice. This variability was not due to the expression of hAPP751SL, however, linear relationship between hPS1M146L mRNA and Aβ production was identified. The Aβ content was related to the incorporation of the hPS1M146L into functional γ‐secretase complexes, detected by the presence of the corresponding human or endogenous PS1‐CTFs. Animals expressing low amount of hPS1M146L mRNA, displayed low hPS1‐CTF incorporation and produced a low amount of Aβ peptides. Conversely, mice with relatively high hPS1 mRNA expression displayed high hPS1‐CTF and high Aβ deposition. Furthermore, the Aβ total and Aβ1‐42 content was increased dramatically by the expression of hPS1M146L (as compared with transgenic APPsl littermates). Therefore, variations in the expression of transgenic form of hPS1M146L in this model, or even between different models, influenced strongly the incorporation of the mutated PS1 into functional γ‐secretase complexes, the production of Aβ peptides and, in consequence, the detrimental effects of Aβ peptides. These data might implicate an “apparent gain‐of‐function” of the γ‐secretase complex by the expression of the mutated PS1M146L. © 2007 Wiley‐Liss, Inc.
Seasonal sea‐level forecasts by canonical correlation analysis—an operational scheme for the U.S.‐affiliated Pacific Islands
Authors: Chowdhury MD. Rashed , Chu Pao‐Shin , Schroeder Thomas , Colasacco Nicole 
Published: January 2007

AbstractThe objective of this study is to develop an operational canonical correlation analysis (CCA) statistical model for sea‐level forecasts in the U. S.‐affiliated Pacific Islands (USAPI) with lead times of several months or longer. The El Niño‐Southern Oscillation (ENSO) climate cycle and the sea‐surface temperatures (SSTs) in the tropical Pacific Ocean are taken as the primary factors in modulating sea‐level variability on the seasonal time scales.Observations revealed that the sea‐level variations in the USAPI are sensitive to ENSO cycle with low sea level during El Niño and high sea level during La Niña events. The correlation between the sea‐level variability and the fluctuations of tropical Pacific SSTs has been found to be strong. The cross‐validated results indicated that the SST‐based CCA model is potentially useful in predicting seasonal sea‐level variations in the USAPI. For all target seasons at 1‐ and 2‐season lead times, the average correlation skill has been found to be 0.50 or better. Based on this operational CCA model, the real‐time forecasts for seasonal sea‐level variations (i.e. deviations with respect to climatology) are published at the official web site of Pacific ENSO Applications Center (PEAC) (http://lumahai.soest.hawaii.edu/Enso/peu/update.html) for planning and decision options regarding hazard management in the USAPI. Copyright © 2007 Royal Meteorological Society
Integration of biophysical and socio‐economic factors to assess soil erosion hazard in the Upper Kaligarang Watershed, Indonesia
Authors: Halim Rohlini , Clemente Roberto S. , Routray Jayant K. , Shrestha Rajendra P. 
Published: January 2007

AbstractSoil erosion is one form of land degradation, which is caused by the interacting effects of numerous factors such as biophysical characteristics and socio‐economic condition of a particular watershed. Previous erosion studies focused on the use of soil erosion models (e.g. USLE, EUROSEM, SLEMSA etc.), which have been developed under local conditions (e.g. United States, Europe, Africa, etc) and mostly use only biophysical factors as inputs to the models. In this study, a methodology that integrates both biophysical and socio‐economic aspects into a framework for soil erosion hazard assessment using principal component analysis (PCA) is described. The analysis is done at the land unit level. With the particular conditions of the study area that is characterized by Inceptisols and Alfisols soil types, nine different land uses with mixed vegetation and forest area dominant in the steep slope, high annual rainfall (>2500 mm), high population with mostly low income and low education, were considered. These were used in formulating a soil erosion hazard index (EHI) equation which relates a number of key factors consisting of biophysical and socio‐economic variables, namely soil texture, slope steepness, land cover, soil conservation practices, income and farmers' knowledge. Weighting and scoring of these key factors were used to develop the EHI equation and to calculate an index value of erosion hazard for every land unit. Results indicate that more than 60% of the area has erosion hazard ranging from moderate to very severe, and most of the land units with high erosion hazard were found at the mountain areas. It was also found that erosion hazard was severe in areas with high silt content, followed by high rainfall and steep slope, low crop cover without any soil conservation practices coupled with lack of awareness on soil erosion and low income. The key factors identified and level of erosion hazard obtained can be used to formulate conservation measures in critical areas which are prone to soil erosion. Copyright © 2007 John Wiley & Sons, Ltd.
Bienzymatic Supramolecular Complex of Catalase Modified with Cyclodextrin‐Branched Carboxymethylcellulose and Superoxide Dismutase: Stability and Anti‐Inflammatory Properties
Authors: Valdivia Aymara , Pérez Yunel , Cao Roberto , Baños Maysa , García Ariel , Villalonga Reynaldo 
Published: January 2007

AbstractA bienzymatic supramolecular assembly of CAT and SOD is reported. CAT was chemically glycosilated with CD branched CMC and then associated with SOD modified with 1‐adamantane carboxylic acid. SOD was remarkably resistant to inactivation by H2O2 and its anti‐inflammatory activity was 4.5‐fold increased after supramolecular association with the modified CAT form.magnified image
Thermoresponsive Self‐Assembly of Short Elastin‐Like Polypentapeptides and Their Poly(ethylene glycol) Derivatives
Authors: Pechar Michal , Brus Jiří , Kostka Libor , Koňák Čestmír , Urbanová Martina , Šlouf Miroslav 
Published: January 2007

AbstractShort polypeptides with four pentad repeats, (VPGVG)4 and (VPAVG)4, were synthesised by manual fluorenylmethoxycarbonyl/tert‐butyl (Fmoc/t‐Bu) solid phase peptide synthesis using a convergent approach. In the next step, the peptides were coupled via their N‐terminus with activated semi‐telechelic poly(ethylene glycol) O‐(N‐Fmoc‐2‐aminoethyl)‐O′‐(2‐carboxyethyl)undeca(ethylene glycol) (Fmoc–PEG–COOH) to yield monodisperse Fmoc‐PEG‐peptide diblock copolymer. Both the presence of the terminal hydrophobic Fmoc group and the hydrophilic PEG chain in the copolymers were shown to play a crucial role in their self‐associative behaviour, leading to reversible formation of supramolecular thermoresponsive assemblies. The peptides and their PEG derivatives were characterised by HPLC, NMR and MALDI‐TOF MS. The associative behaviour of the peptides and their PEG derivatives was studied by dynamic light scattering, MAS NMR and phase contrast microscopy.magnified image
Blue Emission of a Soluble Poly(p‐phenylene) with a Cross‐Conjugated Bisimidazole‐Based Chromophore
Authors: Dierschke Frank , Müllen Klaus 
Published: January 2007

AbstractA novel poly(p‐phenylene) (6) has been synthesized by a cruciform combination of a polyphenylene backbone with 2,2′‐(p‐phenylene)‐bis(4,5‐diphenylimidazole) (5) as an additional, orthogonal chromophore. Polymer 6 showed in solution and in the solid state, a blue‐green emission, which is obviously arising from the second bisimidazole‐based chromophore. UV‐Vis spectroscopy, and cyclic voltammetry revealed that the optical and electronic properties of 6 were fully determined by the incorporated 2,2′‐(1,4‐phenylene)bisimidazole structure. The bisimidazole unit led to high solubility and, despite the steric demand of the substituents, at the same time to the blue‐green emission of the poly(p‐phenylene) (6). In addition, the oxidation of 6 with potassium ferricyanide yielded a low bandgap polymer with a quinoid‐type structure and a bandgap of 1.6 eV.magnified image
Surfactant Chain Length and Tensile Properties of Calcium Carbonate‐Polyethylene Composites
Authors: Osman Maged A. , Atallah Ayman 
Published: January 2007

AbstractMicron‐sized CaCO3 particles free of milling additives were coated with a monolayer of aliphatic carboxylic acids of different chain length (C2, C4, C5, C10, and C18). CaCO3 was compounded with LDPE at different loading, and the tensile properties of the composites were measured and correlated to the length of the alkyl chains tethered to the particles' surface. SEM indicated that the particles are well dispersed (no agglomerates). The inclusions show little influence on the polymer crystallization, and the filler surface treatment leads to a slight decrease in polymer crystallinity that grows with increasing chain length of the fatty acid. The tensile modulus, yield stress, and maximum stress increase with increasing filler volume fraction ϕ, and the dependence is a function of the length of the alkyl chains tethered to the CaCO3 surface. It seems that the interphase thickness and properties depend on the alkyl chain length and strongly influence the modulus and stresses measured. With increasing chain length in the coated organic layer, the interfacial adhesion between the inclusions and the polymer matrix decreases, and the fibril formation increases. The tensile properties are the result of a superimposition of all these effects. The yield and ultimate strains are dominated by the interfacial slippage (increases with growing alkyl chain length) that leads to debonding at high deformations. Surface treatment of CaCO3 with valeric acid leads to the maximum possible tensile modulus, yield stress, and tensile strength combined with a relatively small loss in yield and ultimate strain.magnified image
Reaction Kinetics and Phase Transformations During Cure of a Thermoplastic‐Modified Epoxy Thermoset
Authors: Varley Russell J. 
Published: January 2007

AbstractA comprehensive thermal and rheological characterisation of a commercially important aerospace resin system modified with a thermoplastic toughener is presented here. The primary focus has been the understanding of how the cure kinetics and mechanism relate to other processes such as phase separation during cure. Differential scanning calorimetry has shown that thermoplastic modification does not affect the cure mechanism significantly and that the process was dominated by an autocatalytic process up to vitrification after which diffusion‐controlled processes dominate regardless of thermoplastic concentration. Thermoplastic addition at 10 wt.‐% PEI was found to increase the final cure conversion compared with the neat resin and inhibit the onset of diffusion control below a cure temperature of 160 °C. At 20 wt.‐% PEI concentration the final conversion and the onset of diffusion control were similar until 150 °C, after which they displayed lower values than the neat resin. Rheological analysis showed that the phase separation process could be followed conveniently through the changes in viscosity and exhibited effects consistent with expected variations in morphology. The 10 wt.‐% PEI system displayed abrupt increases in viscosities which were indicative of a dispersed particulate morphology, while the 20 wt.‐% PEI system displayed more complex behaviour consistent with a phase‐inverted or co‐continuous structure. The gelation process was shown to obey a power law model although the local environment or morphology of the reactive epoxide group at higher PEI concentrations was shown to affect the fit to the model.magnified image
Novel Nanosized Aluminium Carboxylates: Synthesis, Characterization and Use as Nanofillers for Protective Polymeric Coatings
Authors: Gläsel Hans‐Jürgen , Hartmann Eberhard , Wennrich Luise , Höche Thomas , Buchmeiser Michael R. 
Published: January 2007

AbstractA mixture of novel aluminium carboxylate nanoparticles and aluminium hydroxide ultrafine powder was prepared via precipitation reaction between Al(2‐PrO)3 and maleic acid. In this mixture both free primary particles occur (mean geometrical size around 40 nm) together with a secondary agglomerated particle fraction of sizes in the low micrometer region. However, centrifugation processes allowed for the removal of the latter and resulted in the formation of size stable nanopowders. Up to 30 wt.‐% of these particles were incorporated into acrylate matrices resulting in low‐viscosity formulations with [η] < 1 000 mPa · s, which allowed for roller application and even spray coating of these nanocomposites at room temperature. Radiation curing of such coatings was accomplished via UV irradiation. In comparison to the corresponding SiO2‐based nanocomposites and carboxylate alumoxane fillers, the cured coatings revealed significantly improved surface mechanical properties.magnified image
Fabrication of Highly Photoluminescent TiO2/PPV Hybrid Nanoparticle‐Polymer Fibers by Electrospinning
Authors: Wang Cheng , Yan Eryun , Huang Zonghao , Zhao Qiang , Xin Yi 
Published: January 2007

AbstractIn this study, we have synthesized highly photoluminescent TiO2/poly (phenylene vinylene) (PPV) hybrid nanoparticle‐polymer fibers by electrospinning a PPV precursor added to a TiO2 sol‐gel solution. The diameters of the hybrid fibers ranged from 100–300 nm and the average size of TiO2 nanoparticles within the fibers was 10–60 nm. FT‐IR analysis indicated that a new band around 1 632 cm−1 assigned to the TiOC vibration appeared, which resulted in the stronger luminance of the fluorescence of the TiO2/PPV hybrid fibers compared to free standing PPV nanofibers.magnified image
Direct Observation of α‐Chloro‐p‐quinodimethane as the Real Monomer in the Gilch Polymerization Leading to Poly(p‐phenylene vinylene)s
Authors: Wiesecke Jens , Rehahn Matthias 
Published: January 2007

AbstractIt is the general consensus that in Gilch polymerizations the 1,4‐bis(chloromethylene)benzene starting material first changes into p‐quinodimethane intermediates which then act as the real monomers. However, direct observation of these intermediates has not been possible so far. This is because usually the p‐quinodimethane auto‐initiates its rapid radical polymerization instantaneously, keeping its concentration extremely low throughout the whole process. Here it is shown that, when the reaction is carried out at very low temperatures, the formation of p‐quinodimethane still proceeds but chain growth is suppressed. Hence, the concentration of the active monomer reaches a level sufficient for NMR analysis.magnified image
Polyelectrolytes Revisited: Reliable Determination of Intrinsic Viscosities
Authors: Wolf Bernhard A. 
Published: January 2007

AbstractThe linear extrapolation of (η − η0)/(η0c) towards c → 0 constitutes the basis of traditional methods to determine intrinsic viscosities [η], where η is the viscosity of polymer solutions of concentration c and η0 is the viscosity of the pure solvent. With uncharged macromolecules this procedure works well; for polyelectrolytes it fails because of the pronounced non‐linearity of the above dependence at high dilution resulting from the increasing electrostatic interactions. This contribution presents a new method for the determination of [η]. It rests upon the application of the laws of phenomenological thermodynamics to the viscosity of polymer solutions and introduces a generalized intrinsic viscosity enabling a comparison of differently charged and uncharged polymers.magnified image
A Novel, One‐Pot Synthesis of Novel 3F, 5F, and 8F Aromatic Polymers
Authors: Diaz Adan M. , Zolotukhin Mikhail G. , Fomine Serguei , Salcedo Roberto , Manero Octavio , Cedillo Gerardo , Velasco Victor M. , Guzman Maria T. , Fritsch Detlev , Khalizov Alexei F. 
Published: January 2007

AbstractA series of novel, linear, soluble, high‐molecular‐weight, fluorinated aromatic polymers has been obtained for the first time using a superacid‐catalyzed polyhydroxyalkylation reaction of fluorinated carbonyl‐containing compounds: 1,1,1,‐trifluoroacetone (1), 2,2,2‐trifluoroacetophenone (2), 2,3,4,5,6,‐pentafluorobenzaldehyde (3), and octafluoroacetophenone (4) with aromatic hydrocarbons such as biphenyl (a), phenyl ether (b), terphenyl (c), and 4,4′‐diphenoxybenzophenone (d). These Friedel‐Crafts‐type aromatic electrophilic substitution reactions are performed at room temperature in trifluoromethane sulfonic acid or in its mixtures with dichloromethane. The polymers obtained are soluble in common organic solvents, and colorless transparent films could be cast from the solutions. 1H and 13C NMR analyses of the polymers synthesized reveal their linear, highly regular structure. The polymers also possess high thermostability.magnified image
Control of SWNT Dispersion by Block Copolymers with a Side‐Chain Polarity Modifier
Authors: Sung Jinwoo , Park Jae Man , Choi U‐Hyeok , Huh June , Jung Bumsuk , Min Byung Gil , Ahn Cheol Hee , Park Cheolmin 
Published: January 2007

AbstractThe dispersion of single‐walled carbon nanotubes (SWNTs) in a non‐polar solvent is controlled with a series of polystyrene‐block‐polybutadiene‐block‐polystyrene (PSBS) block copolymers that contain cholesteryl chloroformate (CC) in side‐chains. Esterification of CC with the partially hydroxylated polybutadiene (PB) blocks allows one to tune the polarity of the block copolymers, which decreases with the amount of CC attached. An excellent dispersion of weak polar SWNTs is observed with PSBS that contains a partially hydroxylated PB block. The dispersion is then significantly deteriorated when the amount of non‐polar CC moieties increases in the block copolymers. A good dispersion is achieved with a polymer that gives rise to strong SWNT–polymer interactions, which ensures contact of the polymer molecules with the nanotube surface, rather than a good solubility of the polymer dispersant in solvent. The stability of the SWNTs in solution arises from unique needle‐like nanowires of the block copolymer aligned perpendicular to the nanotube axis.magnified image
A Polydiacetylene Supramolecular System That Emits Red, Green, and Blue Fluorescence
Authors: Park Eun Young , Kim Jun Woo , Ahn Dong June , Kim Jong‐Man 
Published: January 2007

AbstractA polymer system based on polydiacetylene (PDA) supramolecules that emits red, green, and blue fluorescence has been constructed. The three‐color emitting system is comprised of red‐fluorescent PDA vesicles in which green‐fluorescent fluorescein molecules are encapsulated. Finally, the blue‐fluorescence component is introduced by reacting terminal amine groups on the PDA vesicle surfaces with fluorescamine. Thin PDA‐polymer‐containing poly(vinyl alcohol) films formed by using this strategy display red, green, and blue fluorescence upon excitation with light at specific wavelengths.magnified image
Theory of Multiple‐Detection Size‐Exclusion Chromatography of Complex Branched Polymers
Authors: Gaborieau Marianne , Gilbert Robert G. , Gray‐Weale Angus , Hernandez Javier M. , Castignolles Patrice 
Published: January 2007

AbstractSEC separates complex branched polymers by hydrodynamic volume, rather than by molecular weight or branching characteristics. Equations relating the response of different types of detectors are derived including band broadening, by defining a distribution function N′(M,Vh), the number of chains with molecular weight M and hydrodynamic volume Vh. While the true molecular weight distribution of complex polymers cannot be determined by SEC, irrespective of the detector used, the formalism enables multiple detection SEC data to be processed to both analyze the polymer sample and reveal mechanistic information about polymer synthesis. The formalism also shows how the true weight‐ and number‐average molecular weight, $\overline M _{\rm w}$ and $\overline M _{\rm n}$, can be obtained from correct processing of the hydrodynamic volume distributions.magnified image