bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of ABTS at a Polymer‐Modified Electrode
Authors: Thomas Jennifer H. , Drake J. Michael , Paddock Jean R. , Conklin Sean , Johnson Jay , Seliskar Carl J. , Halsall H. Brian , Heineman William R. 
Published: March 2004

AbstractABTS, 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonate), a colorless dianion that forms a colored radical upon oxidation, was characterized with electrochemistry and spectroscopy and demonstrated to be a detectable analyte in a polymer‐modified spectroelectrochemical sensor. Three positively charged polymers were incorporated into a thin film on an indium tin oxide (ITO) optically transparent electrode and used to concentrate ABTS at the electrode surface. Of the three films, poly(vinylbenzyl trimethyl ammonium chloride)‐poly(vinyl alcohol) (PVTAC‐PVA), poly(diallyldimethylammonium chloride)‐silica (PDMDAAC‐SiO2), and quaternized poly(4‐vinyl‐N‐methylpyridinium nitrate)‐silica (QPVP‐SiO2), PVTAC‐PVA demonstrated the best ability to absorb ABTS. Within 20 min, a change of 0.2 absorbance units at 417 nm and 13.6 μA/cm2 in anodic peak current density in cyclic voltammetry at a scan rate of 0.025 V/s were observed.
A Tubulin‐Based Quantitative Assay for Taxol (Paclitaxel) with Enzyme Channeling Sensing
Authors: Suye Shin‐ichiro , Nakamoto Daichi , Hori Teruo , Sugawara Fumio , Mulchandani Ashok 
Published: March 2004

AbstractWe report the development and characterization of a biosensor for sensitive and rapid determination of the anticancer agent Taxol (paclitaxel). The sensor is based on the interaction of Taxol with its receptor protein tubulin in conjunction with the separation‐free immunosensor technique of enzyme channeling. The sensor system consisted of a three electrode electrochemical cell containing a graphite carbon electrode modified with glucose oxidase and tubulin as working electrode poised at +40 mV (vs. Ag/AgCl). Addition of Taxol, horseradish peroxidase labeled Taxol, glucose and potassium iodide to the cell generated a cathodic current response that was proportional to the concentration of Taxol in the range of 10 to 1 000 pM.
Electroanalytical Determination of Zinc in Human Blood Facilitated by Acoustically Assisted Double Extraction
Authors: Kruusma Jaanus , Banks Craig E. , Lust Enn , Keis Heldur , Nei Lembit , Compton Richard G. 
Published: March 2004

AbstractThe electroanalytical determination of zinc in human blood via an acoustically assisted double extraction technique is reported. First zinc(II) is rapidly extracted from diluted blood via complexation with diphenylthiocarbazone in chloroform through acoustic emulsification of the two phases. After insonation the bulk phases reform and the metal is back extracted by emulsifying with electrochemically clean aqueous acid and the zinc quantified via anodic stripping voltammetry, giving close agreement to the blind independent AAS analysis. The double extraction method is effective since species that otherwise interfere with the direct ASV determination either remain in the initial aqueous phase, or are transferred to the organic phase, but are unlikely to be doubly transferred so producing a ‘clean’ final aqueous medium for ASV.
The Electrochemical Behavior and the Quantitative Determination of Nitrogen Dioxide at a Solid Polymer Electrolyte Supported Pt‐Au Electrode
Authors: Wang Kangli , Yan Heqing , Liu Jun , Sun Xiaoyan , Wang E'feng 
Published: March 2004

AbstractThe electrochemical behavior of NO2 at Au/Nafion, Pt/Nafion and Pt‐Au/Nafion electrodes was investigated by using electrochemical and SEM methods, respectively. It was found that the Pt‐Au/Nafion electrode showed higher electrocatalytic activity than Pt/Nafion and Au/Nafion electrodes. The net current density of Au/Nafion electrode decayed significantly during the reaction, though it showed high initial value. Pt/Nafion and Pt‐Au/Nafion electrodes, on the contrary, showed good stability. A quantitative determination of NO2 concentration was carried out at Pt‐Au/Nafion electrode and a satisfactory linear relationship was found for the NO2 concentration in the range of 0–100 ppm.
Ion‐Selective Electrodes for Thiocyanate Based on the Dinuclear Zinc(II) Complex of a Bis‐N,O‐bidentate Schiff Base
Authors: Bühlmann Philippe , Yahya Lisa , Enderes Rolly 
Published: March 2004

AbstractAn ion selective electrode based on the dinuclear complex formed by two zinc(II) ions and two molecules of the bis‐N,O‐bidentate Schiff base 2,2′‐[methylenebis(4,1‐phenylenenitrilomethylidyne)]bisphenol exhibits thiocyanate selectivity with a good discrimination of nitrite, nitrate, and azide. The selectivities of electrode membranes with various compositions indicate that this potentiometric selectivity is based on the formation of a 1 : 1 complex between the thiocyanate anion and the dinuclear ionophore. The 2 : 1 ratio of thiocyanate ions and the dinuclear ionophore that results from higher ratios of cationic sites and ionophore worsens the selectivity, suggesting that binding of a thiocyanate to both zinc(II) centers of the dinuclear ionophore is not favorable. Interestingly, the selectivity patterns of these electrodes differ radically from that of a highly sulfate selective electrode based on a compound reported previously to be the analogous mononuclear 1 : 1 complex of zinc(II) and the same Schiff base. It is suggested that the previously reported 1 : 1 complex with zinc(II) may indeed have been a polymer of the same elemental composition.
Development of an adaptive discontinuity‐capturing hyperbolic finite element model
Authors: Fang C. C. , Sheu Tony W. H. 
Published: March 2004

AbstractIn this paper we present a five‐parameter Taylor–Galerkin finite element model to simulate Euler equations in a domain of two dimensions. The introduced free parameters are theoretically determined by employing M‐matrix theory to obtain a physically correct and non‐oscillatory solution in regions containing a sharp solution profile. To improve the computational efficiency and solution accuracy, grids are adaptively added to obtain solutions with fewer mesh points. The discontinuity‐capturing finite element model has been validated against test cases, reproducing analytical solutions to the gas dynamic problems under the current investigation. Copyright © 2004 John Wiley & Sons, Ltd.
Interfacial dynamics‐based modelling of turbulent cavitating flows, Part‐1: Model development and steady‐state computations
Authors: Senocak Inanc , Shyy Wei 
Published: March 2004

AbstractThe merits of transport equation‐based models are investigated by adopting an enhanced pressure‐based method for turbulent cavitating flows. An analysis of the mass and normal‐momentum conservation at a liquid–vapour interface is conducted in the context of homogeneous equilibrium flow theory, resulting in a new interfacial dynamics‐based cavitation model. The model offers direct interpretation of the empirical parameters in the existing transport‐equation‐based models adopted in the literature. This and three existing cavitation models are evaluated for flows around an axisymmetric cylindrical body and a planar hydrofoil, and through a convergent–divergent nozzle. Although all models considered provide qualitatively comparable wall pressure distributions in agreement with the experimental data, quantitative differences are observed in the closure region of the cavity, due to different compressibility characteristics of each cavitation model. In particular, the baroclinic effect of the vorticity transport equation plays a noticeable role in the closure region of the cavity, and contributes to the highest level of turbulent kinetic energy there. Copyright © 2004 John Wiley & Sons, Ltd.
Column‐based model of electric field excitation of cerebral cortex
Authors: Fox Peter T. , Narayana Shalini , Tandon Nitin , Sandoval Hugo , Fox Sarabeth P. , Kochunov Peter , Lancaster Jack L. 
Published: March 2004

AbstractA model to explain the orientation selectivity of the neurophysiologic effects of electric‐field transients applied to cerebral cortex is proposed and supported with neuroimaging evidence. Although it is well known that transcranial magnetic stimulation (TMS) excites cerebral cortex in an orientation‐selective manner, a neurophysiologically compelling explanation of this phenomenon has been lacking. It is generally presumed that TMS‐induced excitation is mediated by horizontal fibers in the cortical surfaces nearest to the stimulating coil, i.e., at the gyral crowns. No evidence exists, however, that horizontal fibers are orientation selective either anatomically or physiologically. We used positron emission tomography to demonstrate that TMS‐induced cortical activation is selectively sulcal. This observation allows the well‐established columnar organization of cerebral cortex to be invoked to explain the observed orientation selectivity. In addition, Rushton's cosine principle can used to model stimulation efficacy for an electrical field applied at any cortical site at any intensity and in any orientation. Hum. Brain Mapp. 22:1–16, 2004. © 2004 Wiley‐Liss, Inc.
Enhancement of GABA‐related signalling is associated with increase of functional connectivity in human cortex
Authors: Fingelkurts Andrew A. , Fingelkurts Alexander A. , Kivisaari Reetta , Pekkonen Eero , Ilmoniemi Risto J. , Kähkönen Seppo 
Published: March 2004

AbstractStructural or operational synchrony analysis with EEG was conducted in order to detect functional interaction between cortical areas during an enhanced inhibition induced by the GABAergic agonist lorazepam in a double‐blind, randomized, placebo‐controlled, cross‐over study in eight healthy human subjects. Specifically, we investigated whether a neuronal inhibitory system in the brain mediates functional decoupling of cortical areas. Single‐dose lorazepam administration resulted in a widespread increase in the inter‐area functional connectivity and an increase in the strength of functional long‐range and interhemispheric connections. These results suggest that inhibition can be an efficient mechanism for synchronization of large neuronal populations. Hum. Brain Mapping 22:29–41, 2004. © 2004 Wiley‐Liss, Inc.
Scale‐free dynamics of global functional connectivity in the human brain
Authors: Stam Cornelis Jan , de Bruin Eveline Astrid 
Published: March 2004

AbstractHigher brain functions depend upon the rapid creation and dissolution of ever changing synchronous cell assemblies. We examine the hypothesis that the dynamics of this process displays scale‐free, self‐similar properties. EEGs (19 channels, average reference, sample frequency 500 Hz) of 15 healthy subjects (10 men; mean age 22.5 years) were analyzed during eyes‐closed and eyes‐open no‐task conditions. Mean level of synchronization as a function of time was estimated with the synchronization likelihood for five frequency bands (0.5–4, 4–8, 8–13, 13–30, and 30–48 Hz). Scaling in these time series was investigated with detrended fluctuation analysis (DFA). DFA analysis of global synchronization time series showed scale‐free characteristics, suggesting neuronal dynamics do not necessarily have a characteristic time constant. The scaling exponent as determined with DFA differed significantly for different frequency bands and conditions. The exponent was close to 1.5 for low frequencies (δ, θ, and α) and close to 1 for β and γ bands. Eye opening decreased the exponent, in particular in α and β bands. Fluctuations of EEG synchronization in δ, θ, α, β, and γ bands exhibit scale‐free dynamics in eyes‐closed as well as eyes‐open no‐task states. The decrease in the scaling exponent following eye opening reflects a relative preponderance of rapid fluctuations with respect to slow changes in the mean synchronization level. The existence of scaling suggests that the underlying dynamics may display self‐organized criticality, possibly representing a near‐optimal state for information processing. Hum. Brain Mapping 22:99–111, 2004. © 2004 Wiley‐Liss, Inc.
Fetal brain activity and hemodynamic response to a vibroacoustic stimulus
Authors: Fulford Jonathan , Vadeyar Shantala H. , Dodampahala Sanani H. , Ong Stephen , Moore Rachel J. , Baker Philip N. , James David K. , Gowland Penny 
Published: March 2004

AbstractPrevious studies have demonstrated the practicality of using functional magnetic resonance imaging (fMRI) techniques to assess fetal brain activity. The purpose of this study was to compare the fetal hemodynamic response to that of the adult. Seventeen pregnant subjects, all of whom were at more than 36 weeks gestation were scanned while the fetus was exposed to a vibroacoustic stimulus. Thirteen adult subjects were scanned with an equivalent acoustic stimulus. Of the fetal subjects, two could not be analyzed due to technical problems, eight did not show significant activation, and seven showed significant activation. In all cases, activation was localized within the temporal region. Measures of fetal hemodynamic responses revealed an average time to peak (ttp) of 7.36 ± 0.94 sec and an average percentage change of 2.67 ± 0.93%. In contrast, activation was detected in 5 of 13 adults with an average ttp of 6.54 ± 0.54 sec and an average percentage change of 1.02 ± 0.40%. The measurement of changes in the fetal hemodynamic response may be important in assessing compromised pregnancies. Hum. Brain Mapping 22:118–123, 2004. © 2004 Wiley‐Liss, Inc.
Synthesis of 2,3‐dihydro‐1,3,4‐thiadiazole, thiazole, and triazolo[4,3‐a]pyrimidine derivatives from ethyl benzoylacetate
Authors: Rateb Nora M. , Abdelhamid Abdou O. 
Published: March 2004

AbstractThiophene and thiazole derivatives can be obtained from potassium salt of ethyl 3‐oxo‐3‐phenyl‐2‐[(phenylamino)thioxomethyl]propanoate and ethyl chloroacetate in N,N‐dimethylformamide solution under different conditions. 2,3‐Dihydro‐1,3,4‐thiadiazoles and triazolo[4,3‐a]pyrimidine were obtained from reaction of hydrazonoyl halides with each of thioanilide and pyrimidine‐2‐thione, respectively. Structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthesis route whenever possible. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:107–113, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10222
Synthesis and structural studies of N‐(p‐toluenesulfonyl)‐amino acid 3,5‐di‐tert‐butyl‐2‐phenolamides
Authors: Tlahuextl Margarita , Aguilar‐Castro Liliana , Camacho‐Camacho Carlos , Contreras Rosalinda , Tapia‐Benavides Antonio R. 
Published: March 2004

AbstractThis paper describes the synthesis and structural studies of N‐(p‐toluenesulfonyl)‐amino acid 3,5‐di‐tert‐butyl‐2‐phenolamides by 1H, 13C, and 15N. The presence of intra‐ and intermolecular hydrogen bonds were studied by variable temperature NMR spectroscopy. The molecular structure of two amides in the solid state was determined by X‐ray diffraction experiments. The results show that tert‐butyl substituents in the phenolic ring have important effects in the nature of hydrogen bonds and conformation of these amides. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:114–120, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10223
An improved procedure for phenylselenoetherification of some Δ5‐alkenols using pyridine, Ag2O, and some Lewis acids as catalysts
Authors: Bugarčić Zorica M. , Mojsilović Biljana M. 
Published: March 2004

AbstractAn improved procedure for intramolecular cyclization of some Δ5‐alkenols, using PhSeX (X = Cl, Br) has been developed. We found that cyclization can be facilitated in the presence of pyridine, Ag2O, and some Lewis acids as catalysts. Thus catalytic amount of additives (pyridine and Ag2O) influences higher yields but equimolar amount achieves almost quantitative yield under extremely mild experimental conditions. In the presence of Lewis acids (ZnCl2 and FeCl3) high yields of cyclic ether products are obtained with catalytic amounts. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:146–149, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10227
Methylation of some cyclic triphosphenium ions
Authors: Dillon Keith B. , Olivey Richard J. 
Published: March 2004

AbstractSix cyclic triphosphenium ions, including examples of five‐, six‐, and seven‐membered ring systems, have been successfully methylated by excess methyl triflate to form the corresponding dications. This has been unequivocally established by means of 31P NMR spectroscopy; results are in good agreement with literature data for this type of compound. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:150–154, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10228
Reaction of an ammonium eneselenolate derived from a selenothioacetic acid S‐ester with electron‐deficient alkenes and alkynes
Authors: Murai Toshiaki , Kondo Taichi , Kato Shinzi 
Published: March 2004

AbstractAmmonium eneselenolate 2 derived from selenothioic acid S‐ester 1 was reacted with electron‐deficient alkenes 4 and alkynes 9. Ammonium eneselenolate 2 underwent Michael addition with 4 to give two types of Michael adducts, 5 and 6. Products 6 incorporated two molecules of 4. In contrast, the reaction of 2 with 9 took place at the selenium atom to give γ‐oxo divinyl selenides 10 with high Z‐stereoselectivity. During the further elaboration of the reactivity of the products derived from 2 and carbonyl compounds, unexpected reaction was found in the addition of vinylmagnesium bromide to Se‐vinyl ester 3. The spectroscopic data supported the formation of the enol form 12 of β‐oxo selenothioic acid S‐ester 13. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:187–192, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20003
Novel conversion of 6H‐1,3,5‐oxathiazine S‐oxides into 5‐membered heterocyclic compounds
Authors: Rafiqul Islam Md. , Shimada Kazuaki , Aoyagi Shigenobu , Takikawa Yuji , Kabuto Chizuko 
Published: March 2004

Abstract5H‐1,2,4‐oxathiazoles were efficiently synthesized from 6H‐1,3,5‐oxathiazine S‐oxides by thermal cycloreversion of the substrates and the products were effectively converted into 1,2,4‐thiadiazoles. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:175–186, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20004
The effect of a major cigarette price change on smoking behavior in california: a zero‐inflated negative binomial model
Authors: Sheu Mei‐ling , Hu Teh‐wei , Keeler Theodore E. , Ong Michael , Sung Hai‐Yen 
Published: March 2004

AbstractThe objective of this paper is to determine the price sensitivity of smokers in their consumption of cigarettes, using evidence from a major increase in California cigarette prices due to Proposition 10 and the Tobacco Settlement.The study sample consists of individual survey data from Behavioral Risk Factor Survey (BRFS) and price data from the Bureau of Labor Statistics between 1996 and 1999. A zero‐inflated negative binomial (ZINB) regression model was applied for the statistical analysis.The statistical model showed that price did not have an effect on reducing the estimated prevalence of smoking. However, it indicated that among smokers the price elasticity was at the level of −0.46 and statistically significant.Since smoking prevalence is significantly lower than it was a decade ago, price increases are becoming less effective as an inducement for hard‐core smokers to quit, although they may respond by decreasing consumption. For those who only smoke occasionally (many of them being young adults) price increases alone may not be an effective inducement to quit smoking. Additional underlying behavioral factors need to be identified so that more effective anti‐smoking strategies can be developed. Copyright © 2004 John Wiley & Sons, Ltd.
Determinants of access to physician services in Italy: a latent class seemingly unrelated probit approach
Authors: Atella Vincenzo , Brindisi Francesco , Deb Partha , Rosati Furio C. 
Published: March 2004

AbstractWe examine access to general practitioners and specialists who work in the public and private sectors in Italy using a seemingly unrelated system of probits. We use a latent class formulation that provides a rich and flexible functional form and can accommodate non‐normality of response probabilities. The empirical analysis shows that patient behavior can be clustered in two latent classes. We find that income strongly influences the mix of services. Richer individuals are less likely to seek care from GP's and more likely to seek care from specialists, and especially private specialists. Health status and societal vulnerability are the most important indicators of class membership. Copyright © 2004 John Wiley & Sons, Ltd.
Two New Insecticidal Amide Dimers from Fruits of Piper nigrum Linn.
Authors: Siddiqui Bina S. , Gulzar Tahsin , Begum Sabira , Afshan Farhana , Sattar Fouzia A. 
Published: March 2004

AbstractThe methanolic extract of dried ground seeds of Piper nigrum Linn. afforded fourteen compounds, of which thirteen were amides, including two new isomeric insecticidal amides, pipsaeedine (1) and pipbinine (2), along with eleven known amides and piptaline; (this is the first report of isolation of these compounds from this plant). The structures of 1 and 2 have been elucidated as (E,E)‐1‐[(E)‐5‐(7‐{6‐[5‐(piperidin‐1‐yl)‐5‐oxopent‐3‐enyl]‐1,3‐benzodioxol‐4‐yl}‐1,3‐benzodioxol‐5‐yl)‐1‐oxopenta‐2,4‐dienyl]piperidine and (E,E)‐1‐[(E)‐5‐(4‐{6‐[5(piperidin‐1‐yl)‐5‐oxopent‐3‐enyl]‐1,3‐benzodioxol‐4‐yl}‐1,3‐benzodioxol‐5‐yl)‐1‐oxopenta‐2,4‐dienyl]piperidine, respectively, through extensive 1D‐ and 2D‐NMR spectral studies, while the known constituents have been identified through comparison of their spectral data with those reported in the literature. Compounds 1 and 2 exhibited toxicities of 45.0 and 40.0 ppm, respectively, against fourth instar larvae of Aedes aegypti Liston.
Prognostic factors in children requiring admission to an intensive care unit after hematopoietic stem cell transplant
Authors: Cheuk Daniel Ka Leung , Ha Shau Yin , Lee So Lun , Chan Godfrey Chi Fung , Tsoi Nai Shun , Lau Yu Lung 
Published: March 2004

AbstractThe objectives of this study are to identify prognostic factors of survival to discharge in pediatric hematopoietic stem cell transplant (HSCT) recipients requiring intensive care unit (ICU) admission, and to determine the utility of the Oncological Pediatric Risk of Mortality (O‐PRISM) in predicting death of these patients. A retrospective cohort of 125 pediatric HSCT recipients from October 1992 to September 2002 was analysed to evaluate risk factors of mortality in those admitted to ICU after HSCT. Nineteen patients (median age 7.8 years, 14 boys) required 24 ICU admissions post‐HSCT. The most frequent underlying diseases were acute myeloid leukemia (n=5). The survival rate on discharge from ICU was 54%. In univariate analysis, risk factors of mortality included earlier requirement of ICU admission post‐HSCT (median 34 versus 166 days, p=0.002), a longer delay before ICU admission (median 12 versus 5 h, p=0.02), lack of neutrophil (p=0.011) or platelet engraftment (p=0.008), macroscopic hemorrhage (p<0.001), tachypnoea (p=0.033), hypoxemia (p=0.031), renal impairment (p=0.011), coagulopathy (p=0.012), mechanical ventilation (p<0.001), and an increasing number of organ failures (p=0.003). Macroscopic hemorrhage and mechanical ventilation remained significant in multivariate analysis. Both PRISM and O‐PRISM scores were significant composite prognosticators. It was concluded that mortality of post‐HSCT children requiring ICU admission is high, especially in those with poor prognosticators. Copyright © 2004 John Wiley & Sons, Ltd.