bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of food additive azo dyes at an HMDE with adsorptive stripping voltammetry
Authors: Castrillejo Yolanda , Pardo Rafael , Barrado Enrique , Batanero Pedro Sánchez 
Published: February 2006

AbstractControlled adsorptive accumulation of the food additives (azo dyes) ponceau 4R, Allura Red, and carmoisine at a hanging mercury drop electrode (HMDE) provided the basis for their determination by stripping voltammetry at nanomolar concentration levels. The adsorptive stripping response was evaluated with respect to experimental parameters such as accumulation potential, preconcentration time, pH, and bulk concentration. Best results were obtained using an ammonia buffer as the supporting electrolyte; depending on the dye, detection limits of 0.071, 0.076, and 0.043 nM were, respectively, achieved in pure dye solutions. The simultaneous determination was carried out by means of the generalized standard addition method.
Amperometric flow‐injection analysis of L‐glutamate using an immobilized enzyme reactor: Amplification by substrate recycling
Authors: Yao Toshio , Kobayashi Naokazu , Wasa Tamotsu 
Published: February 2006

AbstractAn amperometric flow injection system with an immobilized enzyme reactor that gives responses amplified by substrate recycling was employed for the highly sensitive determination of L‐glutamate. An L‐glutamate oxidase/glutamic‐pyruvic transaminase coimmobilized reactor was incorporated at fixed positions in a flow system. In the presence of sufficient amounts of L‐alanine and oxygen in the carrier solution, L‐glutamate was repeatedly converted to 2‐oxoglutarate by L‐glutamate oxidase, and the 2‐oxoglutarate produced was subsequently converted back to L‐glutamate by glutamic‐pyruvic transaminase during the passage through the enzyme reactor. As a result of this recycling reaction, a large amount of hydrogen peroxide was produced in the reactor and could be detected amperometrically at a downstream platinum detector. L‐Glutamate was determined with a 20‐ to 30‐fold increase in sensitivity compared to the unamplified responses. The detection limit was 1 pmol of L‐glutamate.
Charge transfer across a conducting polypyrrole membrane separated by two electrolyte solutions
Authors: Wang Erkang , Liu Yuqing , Samec Z. , Dvořák C. 
Published: February 2006

AbstractThis article describes anion transfer across a conducting polypyrrole membrane (PPM) using cyclic voltammetry with a four‐electrode system. The transfer process of both chloride and nitrate anions across the polypyrrole membrane used to separate two pools of electrolyte solutions has been studied. A wide potential window beyond 3 V was obtained, and well‐developed voltammograms for the transfer of nitrate and chloride anions appeared within this window. The transfer process depends on the ion size, the ion charge, and the surface characteristics of the polypyrrole membrane. The one‐way transfer phenomenon observed in different potential‐bias directions can be explained by the asymmetrical ion channel model of the polypyrrole membrane.
Climate and pre‐Columbian settlement at Anse à la Gourde, Guadeloupe, Northeastern Caribbean
Authors: Beets C.J. , Troelstra S.R. , Grootes P.M. , Nadeau M.‐J. , Borg K. van der , Jong A.F.M. de , Hofman C.L. , Hoogland M.L.P. 
Published: February 2006

AbstractThe authors present a reconstruction of precipitation, seasonality, and vegetation cover over the period from 200 cal yr B.C. to 1600 cal yr A.D. for the archaeological site of Anse à la Gourde, Guadeloupe, based on the oxygen and carbon isotope composition of accelerator mass spectrometry (AMS) 14C‐dated aragonitic shells of the landsnail Bulimulus guadaloupensis. The results show that the Late Cedrosan Saladoid population (˜400–800 cal yr A.D.) disappeared at the beginning of a dry and stormy period lasting from 800 to 1000 cal yr A.D. The Mamoran Troumassoid started to populate the site around 1000 cal yr A.D. when the climate became wetter, and remained until ˜1300 cal yr A.D. The snail‐shell carbon isotope values changed significantly around the period that the Late Cedrosan Saladoid occupation started. This indicates a vegetational response either to the wetter conditions, or because of the replacement of existing C4 plant vegetation by introduced C3 crops. © 2006 Wiley Periodicals, Inc.
Extracellular matrix deposition by fibroblasts is necessary to promote capillary‐like tube formation in vitro
Authors: Berthod François , Germain Lucie , Tremblay Nathalie , Auger François A. 
Published: February 2006

AbstractThe contribution of the cellular and fibrillar microenvironment to angiogenesis still remains unclear. Our purpose was to evaluate the effect of the extracellular matrix deposited by fibroblasts on the capacity of human endothelial cells to form capillaries in vitro. We have drastically decreased the amount of extracellular matrix surrounding fibroblasts in our model of endothelialized‐reconstructed connective tissue (ERCT) by culturing it without ascorbate. Under these conditions, the number of capillary‐like tubes (CLT) formed by endothelial cells was reduced by up to 10‐fold after 31 days of culture compared to controls. This decrease was due neither to a variation of MMP‐2 and MMP‐9 secretion, nor to a reduction in the number of fibroblasts and/or endothelial cells, or a diminution of fibroblast growth factor 2 (FGF2) synthesis. The secretion of vascular endothelial growth factor (VEGF) by fibroblasts accounted for 25–70% of the capillary‐like tube formation when tissues were cultured in the presence or absence of ascorbate, as demonstrated by VEGF‐blocking studies. The culture of endothelial cells on a similar extracellular matrix but in the absence of living fibroblasts did not promote the formation of CLT, even when tissues were fed with fibroblast‐conditioned medium. Thus, the deposition of a rich extracellular matrix by living fibroblasts appeared necessary, but not sufficient to promote capillary‐like formation. Fibroblasts seem to induce endothelial cells to spontaneously form CLT by secreting and organizing an abundant extracellular matrix, which creates a microenvironment around cells that could in turn trap growth factors produced by fibroblasts and promote three‐dimensional cell organization. J. Cell. Physiol. 207: 491–498, 2006. © 2006 Wiley‐Liss, Inc.
RepairNET: A bioinformatics toolbox for functional exploration of DNA damage response
Authors: Li Wei , Wen Liting , Feng Jin‐an 
Published: February 2006

AbstractDNA damage response is one of the essential cellular mechanisms to maintaining the genomic integrity of the cell. Aberrations in the mechanism of DNA damage response often result in cancer. We describe here RepairNET, a protein–protein interaction network associated with the DNA damage response. RepairNET is assembled from the published literature by using a protocol that involved computational data mining of the MEDLINE and manual curation. This network represents the current knowledge on the intrinsic signaling pathways related to the DNA damage response process. RepairNET currently contains more than 1,200 proteins with over 2,300 functional interactions. A number of web‐interface tools have been implemented to facilitate a user‐friendly environment. The users can navigate through the cellular network associated with the DNA damage response via a Java‐based interactive graphical interface. In order to help users explore the functional relationships between the interacting proteins, we have assigned functional domains to the proteins in RepairNET based on their sequences. A total of 365 unique functional domains are assigned. RepairNET is available online at http://guanyin.chem.temple.edu/RepairNET.html. It could become an essential resource center for cancer research, providing clues to understanding the functional relationship between proteins in the network, and to building scientific models for the mechanism of DNA damage response and cancer proliferation. J. Cell. Physiol. 207: 293–299, 2006. © 2006 Wiley‐Liss, Inc.
Weak organic acids induce taurine release through an osmotic‐sensitive process in in vivo rat hippocampus
Authors: Solis J. M. , Herranz A. S. , Herreras O. , Menéndez N. , del Rio R. Martin 
Published: February 2006

AbstractIsotonic media containing sodium salts from weak organic acids induce cell swelling in several experimental preparations (Grinstein et al., 1984; Jakubovicz et al., 1987). In vivo perfusion of rat dentate gyrus, using a microdialysis probe, with modified Krebs‐Ringer bicarbonate solutions in which 50 mM NaCl was isotonically substituted by the sodium salts from organic acids with a pKa value of >2 (acetate, propionate, or pyruvate), induced a reversible increase in the extracellular taurine concentration. By contrast, similar NaCl substitutions with sodium salts from the stronger organic acids isethionate and methanesulfonate did not change extracellular taurine levels. Extracellular taurine increases evoked by acetate, propionate, or pyruvate were almost completely abolished when the perfusion liquid was made hypertonic by adding sucrose (50 mM). A 30% reduction of the acetate‐induced extracellular taurine increase was observed both when amiloride was present or when the [Na+]0 was lowered. Both conditions are known to inhibit Na+/H+ exchange. These results are compatible with the hypothesis that acid load‐induced taurine release is stimulated by an osmotic sensitive mechanism, part of which is dependent on activation of the Na+/H+ exchange.
Brain regional distribution of physostigmine and its relation to cerebral blood flow following intravenous administration in rats
Authors: Scremin O. U. , Scremin A. M. E. , Somani S. M. , Giacobini E. 
Published: February 2006

Abstract3H‐labeled physostigmine (50 μg·kg−1) was administered intravenously to rats, and its concentration in brain tissue and spinal cord was assessed by quantitative autoradiography. Regional cerebral blood flow (rCBF) was measured with iodo‐14C‐antipyrine auto‐radiography in control rats and in animals injected i.v. with a dose of physostigmine similar to that used for the distribution studies. Tissue concentration of 3H‐physostigmine was correlated with rCBF for 37 brain regions. A high degree of correlation was found at 0.5 min after drug injection, r (correlation coefficient) = 0.87. This association decreased at later times (5 min r = 0.73, 12 min r = 0.24). Structures with high cholinesterase activity (caudate‐putamen, amygdala, hippocampus) showed greater retention of physostigmine over time. The highest initial physostigmine concentrations were found in regions lacking a blood‐brain barrier (pineal gland, median eminence, choroid plexus) (range = 10.4–23.8 nCi/mg) and the lowest in white matter (corpus callosum, internal capsule, hippocampus commisure, spinal cord dorsal column) (range = 1.2–2.6 nCi/mg). Initial concentrations of the drug in the areas in which physostigmine induced vasodilatation (motor, sensory, temporal and occipital cortex, claustrum, and superior collicullus) were not different from concentrations in areas of comparable basal rCBF in which no such effect was observed. Variations in drug access to brain regions, then, do not explain the topographical variations of the cerebrovascular action of physostigmine.
Greffage d'acides aminés possédant une troisième fonction sur un polymère, 2. Fixation de tyrosine et de lysine sur un polymère α‐monofonctionnel. Model de réaction
Authors: Gueniffey Henri , Garnier Raymonde , Pinazzi Christian 
Published: February 2006

AbstractLa tyrosine et la lysine, sous forme de complexe cuivrique (1 et 5) ont été fixées respectivement par leur fonction phénol et amine sur des alcools primaires dont la chaine comprend 2, 8 et 16 atomes de carbone.
Stabilisation et caractérisation des polybutadiènes‐1,2 liquides cyanométhylés par réaction couplée à l'hydroboration
Authors: Pinazzi C. , Vassort J. , Jean F. , Reyx D. 
Published: February 2006

AbstractL'existence de structures trialkylboranes résiduelles dans les polydiènes modifiés par réaction couplée à l'hydroboration confère aux produits obtenus une instabilité résultant de la réactivité de ces structures à l'air. Pour les polydiènes cyanométhylés par cette voie, une méthode d'élimination des structures trialkylboranes par une réaction sélective, spécifique et quantitative a été recherchée: l'optimisation de la réaction de cyanométhylation n'a pas permis une élimination quantitative; l'acétolyse est, selon les conditions, non quantitative ou non spécifique tandis que la réaction d'oxydation alcaline s'est révélée spécifique et quantitative mais non totalement sélective: elle provoque simultanément et à de faibles taux l'hydrolyse parasite des structures cyanométhylées. La caractérisation des produits obtenus par cette dernière methode a été réalisée par analyse spectrographique (IR et NMR) des produits eux‐měmes, de leurs dérivés acétylés et de leurs dérivés réduits.
Telechele Oligomere, 3. Oligoäthylene durch radikalische Polymerisation mit Diacylperoxiden als Initiator
Authors: Guth Werner , Heitz Walter 
Published: February 2006

AbstractDie Möglichkeit der Bildung von telechelen Oligoäthylenen wurde durch die Analyse der Reaktionsprodukte von Dihexanoylperoxid und Äthylen studiert. Bei hohen Temperaturen (>200°C) erhält man vor allem unverzweigte Paraffine mit gerader C‐Atomanzahl (Kombinationsprodukt). Eine Reaktionstemperatur von 95°C führt dagegen fast ausschließlich zu Paraffinen mit ungerader C‐Atomzahl. Die Ursache dafür ist ein durch wachsende Alkylradikale ausgelöster, induzierter Zerfall des Dihexanoylperoxids, der unter H‐Abstraktion in β‐Position zur Carbonylgruppe erfolgt. Dieser induzierte Zerfall wird auch beim Zerfall von Dihexanoylperoxid in Abwesenheit von Äthylen beobachtet.
Studies on the copolymerization of acrylonitrile with butyl acrylate, vinylidene dichloride, and styrene
Authors: Tomescu Margareta , Simionescu Cristofor 
Published: February 2006

AbstractCopolymer composition studies are reported, for different mole fractions of acrylonitrile (AN), butyl acrylate (BA), vinylidene dichloride (CV), and styrene (S) in the initial monomer mixture. A partial azeotropy of acrylonitrile was found.
Stereochemistry of copolymerization of optically active 3‐phenyl‐1,2‐epoxypropane with carbon dioxide
Authors: Hirano Takashi , Inoue Shohei , Tsuruta Teiji 
Published: February 2006

AbstractThe stereochemistry of alternating copolymerization of carbon dioxide with S‐(–)‐3‐phenyl‐1,2‐epoxypropane (5) using a diethylzinc/water system as catalyst was investigated. The optically active copolymer, poly[(oxycarbonyloxy)‐1‐benzylethylene] (6), was hydrolyzed and the epoxide unit was transformed into the form of 1,2‐bis(trimethylsilyloxy)‐3‐phenylpropane (8). From the determination of optical activity of this ether, it is concluded that the ring opening of 5 in the copolymerization takes place predominantly at the methylene‐oxygen linkage. The substituent effect on the ring opening mode of oxiranes is also discussed.
Comparative reactivities of electrogenerated radical cations in cationic polymerization
Authors: Glasel Arnold , Murray Kenneth , Funt B. Lionel 
Published: February 2006

AbstractPersistent radical cations were produced electrochemically from the parent hydrocarbons 9,10‐diphenylanthracene (DPA), 9‐phenylanthracene (9‐PA), 9,10‐dimethylanthracene (DMA), rubrene (Ru), triphenylene (TP), 1,3,6,8‐tetraphenylpyrene (TPP), and perylene (P). The stabilities of these cations in the absence of monomer were

equation image

The rates of decay of increased with the dielectric constant of the solvent and were 4 to 5 times greater in CH3CN than in CH2Cl2 or C6H5NO2.The kinetics of the reaction of the radical cation with monomer were investigated for styrene and isobutyl vinyl ether. For styrene and or a first order dependence on the radical cation concentration was found. However, decay was unaffected by the addition of styrene and polymerization was not initiated. With and isobutyl vinyl ether a first order dependence on cation was observed and polymers were obtained.Electropolymerizations were also conducted with the generation of radical cations in situ and the rates of monomer consumption and polymer production were measured. The passage of the same electric charge in Faradays (1 Faraday=96496 coulomb) resulted in the polymerization of different amounts of the monomer and generally paralleled the reactivities found for the various radical cations.
Gelation kinetics in aqueous solutions of syndiotactic‐rich poly(vinyl alcohol)
Authors: Ogasawara Kenji , Yuasa Kouji , Matsuzawa Shuji 
Published: February 2006

AbstractAqueous solutions of Syndiotactic‐rich poly(vinyl alcohol) (PVA) form thermally reversible gels. The volume of the solution decreases with gelling time on standing at isothermal condition. Assuming that the gelation is due to the crystallization of PVA, the kinetics of isothermal crystallization from 5 wt.‐% aqueous solutions of PVAs having 64,3 mol‐% syndiotactic diads was investigated as a function of temperature (45–90°C), using dilatometry. The maximum in the overall rate of crystallization appeared at 60°C, regardless of the degree of polymerization of PVA. Since the values of n in the Avrami equation vary from about 1 to 2, it was apparent that the crystallization from aqueous solution of the polymer proceeded in the fashion of one‐dimensional growth and heterogeneous, diffusion controlled nucleation. The phase diagram revealed that the syneresis of the gel was caused by the crystalline phase separation which supports the gelation accompanying crystallization.
Pair distribution function and pair potential of lattice model chains under theta conditions, 1. Numerical evaluation
Authors: Olaj Oskar Friedrich , Pelinka Kurt Heinz 
Published: February 2006

AbstractEnsembles of unbranched non‐selfintersecting 4‐way cubic lattice chains consisting of 100 chains each occupying 50 lattice points have been developed for Θ‐conditions by a Metropolis‐Rosenbluth‐Monte‐Carlo technique using a kind of square well potential to describe the segment‐segment interaction. For these equilibrated ensembles the pair distribution function G(R) and the average pair potential U(R) have been estimated by calculating the intermolecular energy for all isolated pairs, which can be depicted from the ensemble, as a function of the distance of the centers of gravity R of the two chains. The resulting G(R) being less than one for small R and exceeding one for large R does not correspond to that of an ideal gas. This means that for thermodynamic reasons alone there can be no free interpenetration of chains at the Θ‐point. U(R) can be split into a repulsive and an attractive part both being approximately Gaussian in type. Thus, U(R) at the Θ‐point can be represented by the general expression.

with A>A′ and a>a′.
Product attributes for business markets: Implications for selling and sales management
Authors: Lichtenthal J. David , Goodwin Stephen A. 
Published: February 2006

AbstractThis article offers a conceptual framework for classifying attributes of offerings in a business‐marketing context. Typologies on the nature of product‐related attributes and classification of industrial products are synthesized for viewing levels of product meaning. Repertory grid procedures first developed in clinical psychology and recently adapted for use in business settings are presented as an approach for eliciting salient/determinant attributes. Enhanced effectiveness of the classic industrial selling process is demonstrated along with implications for managing the sales force. © 2006 Wiley Periodicals, Inc.
The capillary contact angle, II: The inclined plane
Authors: Finn Robert , Shinbrot Marvin 
Published: February 2006

AbstractIn an earlier paper an hypothesis on the nature of the forces resisting motion of a liquid drop on a support surface II was introduced and tested in the (rotationally symmetric) case for which ll is a horizontal plane. In the present work II is chosen as an inclined plane, so that rotational symmetry fails. The hypothesis leads to a formal series development; in a restricted case the result is verified by a perturbation analysis, which yields the identical series.The series predictions are compared with results of computer calculations. A consequence of the analysis is an estimate for a Bohd number B0, such that a further increase in B would result in the fluid penetrating the support surface; thus an absolute upper bound B0, for stability of the envisaged configuration is obtained.
A non‐linearly stable implicit finite element algorithm for hypersonic aerodynamics
Authors: Iannelli G. S. , Baker A. J. 
Published: February 2006

AbstractA generalized curvilinear co‐ordinate Taylor weak statement implicit finite element algorithm is developed for the two‐dimensional and axisymmetric compressible Navier‐Stokes equations for ideal and reacting gases. For accurate hypersonic simulation, air is modelled as a mixture of five perfect gases, i.e. molecular and atomic oxygen and nirogen as well as nitric oxide. The associated pressure is then determined via Newton solution of the classical chemical equilibrium equation system. The directional semi‐discretization is achieved using an optimal metric data Galerkin finite element weak statement, on a developed ‘companion conservation law system’, permitting classical test and trial space definitions. Utilizing an implicit Runge‐Kutta scheme, the terminal algorithm is then non‐linearly stable, and second‐order accurate in space and time on arbitrary curvilinear co‐ordinates. Subsequently, a matrix tensor product factorization procedure permits an efficient numerical linear algebra handling for large Courant numbers. For ideal‐ and real‐gas hypersonic flows, the algorithm generates essentially non‐oscillatory numerical solutions in the presence of strong detached shocks and boundary layer inviscid flow interactions.
Navier‐Stokes simulation of flow through a highly contoured subsonic diffuser
Authors: Chyu W. J. , Bencze D. P. 
Published: February 2006

AbstractThe flow through a highly offset subsonic diffuser with cross‐sectional profiles that varied from rectangular at the duct entrance to circular a t the engine face was numerically simulated. A multizonal approach combined with a two‐grid topology was used to represent both the internal and external flow fields, and an implicit, approximately‐factored, partially flux‐split finite‐difference algorithm was used to solve the three‐dimensional thin‐layer Navier‐Stokes equations. The computed static pressures along the inlet wall and total pressures on the engine face were compared with experimental data. In addition, the overall flow field within the duct was examined in detail. Good agreement is shown between experiment and computations, with the limiting factor being the lack of a reliable turbulence model for internal flow problems.
A staggered mesh finite difference scheme for the computation of compressible flows
Authors: Sanders Richard 
Published: February 2006

AbstractA simple high resolution finite difference technique is presented to approximate weak solutions to hyperbolic systems of conservation laws. The method does not rely on Riemann problem solvers and is therefore easy to extend to a wide variety of problems. The overall performance (resolution and CPU requirements) is competitive with other state‐of‐the‐art techniques offering sharp non‐oscillatory shocks and contacts. Theoretical results confirm the reliability of the approach for linear systems and non‐linear scalar equations.