bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amperometric Detection of Morphine at Preheated Glassy Carbon Electrode Modified with Multiwall Carbon Nanotubes
Authors: Salimi Abdollah , Hallaj Rahman , Khayatian Gholam‐Reza 
Published: January 2005

AbstractA highly sensitive and fast responding sensor for the determination of morphine is described. The multiwall carbon nanotubes immobilize on preheated glassy carbon electrode (5 min at 50 °C) by gently rubbing of electrode surface on a filter paper supporting the carbon nanotubes.The results indicated that carbon nanotubes(CNTs) modified glassy carbon electrode exhibited efficiently electrocatalytic oxidation for morphine with relatively high sensitivity, stability and long life. Under conditions of cyclic voltammetry, the potential for oxidation of morphine is lowered by approximately 100 mV and the current is enhanced significantly (10 times) in comparison to the bare glassy carbon electrode at wide pH range (2–9). The electrocatalytic behavior is further exploited as a sensitive detection scheme for morphine determination by hydrodynamic amperometry. Under the optimized conditions the calibration plots are linear in the concentration range 0.5–150 μM with the calculated detection limit (S/N=3) of 0.2 μM and sensitivity of 10 nA/μM and a relative standard deviation (RSD) of 2.5% (n=10). The amperometric response is extremely stable, with no loss in sensitivity over a continual 30 min operation. Such attractive ability of multiwall carbon nanotubes (MWCNTs) modified GC electrode, suggests great promise for a morphine amperometric sensor. Finally the ability of the modified electrode was evaluated for simultaneous determination of morphine and codeine.
Adsorptive Stripping Voltammetric Determination of Amitrole at a Multi‐Wall Carbon Nanotubes Paste Electdrode
Authors: Chicharro M. , Bermejo E. , Moreno M. , Sánchez A. , Zapardiel A. , Rivas G. 
Published: January 2005

AbstractThis work reports the excellent electrocatalytic activity of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi‐wall carbon nanotubes (MWNT) within mineral oil toward the oxidation of 3‐amino‐1H‐1,2,4‐triazole (amitrole). The quantification is performed by adsorptive stripping voltammetry (AdSV). The influence of the paste composition and surface pretreatments as well as the amitrole accumulation conditions on the adsorption and further electrooxidation of this herbicide is described. After potentiodynamic pretreatment in 0.050 M phosphate buffer pH 7.4 the amitrole oxidation signal shifts 250 mV toward more negative potential and the sensitivity increases 29 fold, demonstrating that pretreated CNTPEs are extremely useful for a highly sensitive determination of amitrole down to the sub‐μM levels. The oxidation peak current is proportional to the amitrole concentration over the range from 0.8 to 7.0 μM (5 min accumulation), with a detection limit of 0.6 μM (48 μgL−1) and a precision of 4.3%, n=20. The proposed method was used for the determination of amitrole in spiked river water (Alberche River (Madrid, Spain)) and tap water samples (Madrid, Spain) at levels higher than 0.6 μM.
Improvement of Analytical Characteristic of Calcium Selective Electrode with Conducting Polymer Contact. The Role of Conducting Polymer Spontaneous Charge Transfer Processes and Their Galvanostatic Compensation
Authors: Michalska Agata 
Published: January 2005

AbstractIn this report processes affecting the analytical characteristic of all‐solid‐state, conducting polymer–polypyrrole based cation selective sensors are discussed on an example of a Ca‐electrode. It is shown that conditioning of the obtained electrode is coupled with transducer spontaneous discharge leading to accumulation of calcium cations in the polymer phase. As an ultimate result of this process, the sensor detection limit is close to 10−5 M, similarly as for traditional internal solution electrodes. The compensation of polypyrrole spontaneous charge transfer process over conditioning, by anodic galvanostatic polarization, prevents Ca2+ accumulation and results (in subsequent open circuit calibration) in linear responses within the activities range from 0.1 M to 10−10 M. In dilute solution, due to limited accessibility of cations in the solution and relatively high amount of cations present in the transducer phase, the spontaneous charging process of conducting polymer determines the accessible detection limit. It is also shown that in this case the linear range of responses can be extended to reach significantly lower activities under conditions of polarized electrode potentiometry, applying a cathodic current. The outstanding stability of the open circuit equilibrated all‐solid‐state sensor is attributed to accumulation of primary ions in the sensor transducer phase during conditioning.
Speciation of Inorganic Arsenic in Waters by Potentiometric Flow Analysis with On‐Line Preconcentration
Authors: Rodríguez J. A. , Barrado E. , Vega M. , Lima J. L. F. C. 
Published: January 2005

AbstractA potentiometric flow system has been developed for the direct determination of arsenic(V) in water samples after on‐line preconcentration in a minicolumn packed with a new adsorbent material selective to As(V). Iron oxyhydroxide embedded in silica gel was synthesized and used simultaneously as adsorbent material in the minicolumn and as selective component in a tubular potentiometric electrode. In the first step, the sample solution is mixed on‐line with phosphate buffer of pH 7 and pumped through the minicolumn to adsorb As(V). The insertion of the minicolumn in the mobile section of a homemade injector‐commutator allows to relocate the minicolumn to desorb the retained As(V) in the second step. The desorption is maximum in the presence of 0.1 M phosphate of pH 12. Maximum response of the tubular selective membrane is achieved in phosphate buffer of pH 7. On‐line oxidation of As(III) to As(V) by iodine (I3−) in the presence of phosphate buffer of pH 7 allows the determination of total As as As(V) and then the speciation of inorganic arsenic, since As(III) can be estimated as the difference between total As and As(V). In the optimized experimental conditions, a linear range of 40–500 μg L−1 for As(V), and detection limits of 30.6 and 38.6 μg L−1 for As(V) and total As, respectively, were obtained.The flow system has been successfully applied to the determination of inorganic arsenic species in groundwater samples collected in areas affected by arsenic contamination. Relative standard deviation of replicated determinations of As in groundwater samples was always below 5%.
Anion Selective Potentiometric Sensor Based on Gallium Nitride Crystalline Membrane
Authors: Alifragis Yiannis , Konstantinidis Giorgos , Georgakilas Alexander , Chaniotakis Nikos 
Published: January 2005

AbstractGallium nitride (GaN) (0001) grown on sapphire has been used as a sensor element for the development of a potentiometric sensor. The GaN‐based ion‐selective electrode has pH sensitivity which originates from the direct interaction of the gallium with the hydroxide ions. At the same time the sensor shows very good selectivity towards the very hydrophilic anion of orthophosphate, over the very lipophilic ClO4−. Potentiometry and impedance spectroscopy suggest that the observed potentiometric sensitivity originates from the direct interaction of anions in solution with the acidic gallium(III) on the surface of the GaN (0001) crystal. This is also supported by the fact that the gallium atoms are electron deficient due to the induced polarity of the Ga to the N bond, enhancing the electrostatic interaction between the Lewis basic anions. The semiconductor properties of the GaN allow for its application as an all solid‐state semiconductor‐based anion potentiometric sensor, or alternatively as the transducer in composite cation sensitive potentiometric sensors. The latter has been demonstrated with the deposition of a potassium selective liquid polymeric membrane on top of the GaN surface.
Enantioselective Detection of D‐ and L‐Phenylalanine Using Optically Active Polyaniline
Authors: Sheridan Edel M. , Breslin Carmel B. 
Published: January 2005

AbstractChiral conducting polyaniline, which was prepared electrochemically from (+) and (−) camphorsulfonic acid, was utilized for the enantiomeric detection of phenylalanine in neutral phosphate buffer solution. Following electropolymerization the polymer films were dedoped in aqueous ammonia and subsequently shown to maintain their chiral character. The electrochemical window for this polymer was determined to be between 0.2 V and 0.8 V (vs. SCE) and enantiomeric discrimination between L‐ and D‐phenylalanine was seen with the application of differential pulse voltammetry. The (+) chiral polymer is shown to behave as an enantiomeric detector for the D enantiomer producing a peak in the voltammogram at ca. 0.7 V (vs. SCE) while the inverse is true for the (−) polymer, which detects the L enantiomer.
Well‐balanced finite volume evolution Galerkin methods for the shallow water equations with source terms
Authors: Lukáčová‐Medvid'ová M. , Vlk Z. 
Published: January 2005

AbstractThe goal of this paper is to present a new well‐balanced genuinely multi‐dimensional high‐resolution finite volume evolution Galerkin method for systems of balance laws. The derivation of the method will be illustrated for the shallow water equation with geometrical source term modelling the bottom topography. The results can be generalized to more complex systems of balance laws. Copyright © 2005 John Wiley & Sons, Ltd.
On the performance of discrete adjoint CFD codes using automatic differentiation
Authors: Müller J.‐D. , Cusdin P. 
Published: January 2005

AbstractAdjoint methods are a computationally inexpensive way of deriving sensitivity information where there are fewer dependent (cost) variables than there are independent (input) variables. Automatic differentiation (AD) software makes it possible to create discrete adjoint codes with minimal human effort, an issue that had previously restricted acceptance of adjoint CFD codes. In terms of computational performance, automatic code is often assumed to be inferior to hand code. The structure of the underlying code is critical to the performance of the transformed code. This paper reviews the implementation of AD on Fortran CFD codes and gives details of how small rearrangements can be used to produce competitive tangent and adjoint code using source transformation AD. Copyright © 2005 John Wiley & Sons, Ltd.
Prediction of jet flows in the supersonic nozzle and diffuser
Authors: Liu Yi , Bellhouse Brain J. 
Published: January 2005

AbstractThe authors' recently‐developed code for a needle‐free powdered vaccine delivery device, the epidermal powdered inject system (EPI), is summarized in this paper. The behaviour of supersonic jet flows, which accelerate micron sized powdered vaccines to penetrate human skin or mucosal tissue, is therefore of great importance. A well‐established modified implicit flux vector splitting (MIFVS) solver for the Navier–Stokes equations is extended to study numerically the transient supersonic jet flows of interest. A low Reynolds number k–ε turbulence model, with the compressibility effect considered, is integrated into MIFVS solver to predict the turbulent structures and interactions with inherent shock systems. The results for the NASA validation case NPARC, Venturi and contoured shock tube (CST) of the EPI system are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Elimination AD applied to Jacobian assembly for an implicit compressible CFD solver
Authors: Tadjouddine Mohamed , Forth Shaun A. , Qin Ning 
Published: January 2005

AbstractIn CFD, Newton solvers have the attractive property of quadratic convergence but they require derivative information. An efficient way of computing derivatives is by algorithmic differentiation (AD) also known as automatic differentiation or computational differentiation. AD allows us to evaluate derivatives, usually at a cheap cost, without the truncation errors associated with finite‐differencing. Recently, efficient and reliable AD tools for evaluating derivatives have been published. In this paper, we use some of the best AD tools currently available to build up the system Jacobian involved in the solution of a finite‐volume parabolized Navier–Stokes (PNS) solver. Our aim is to direct scientists and engineers confronted with the calculation of derivatives to the use of AD and to highlight those AD tools that they should try. Moreover, we introduce an AD tool that produces Jacobian code that runs usually twice as fast as that from conventional AD tools. We further show that the use of AD increases the performance of a Newton‐like solver for the PNS equations. Copyright © 2005 John Wiley & Sons, Ltd.
Automated post‐hoc noise cancellation tool for audio recordings acquired in an MRI scanner
Authors: Cusack Rhodri , Cumming Nick , Bor Daniel , Norris Dennis , Lyzenga Johannes 
Published: January 2005

AbstractThere are several types of experiment in which it is useful to have subjects speak overtly in a magnetic resonance imaging (MRI) scanner, including those studying the articulatory apparatus and the neural basis of speech production, and fMRI experiments in which speech is used as a response modality. Although it is relatively easy to record sound from the bore, it can be difficult to hear the speech over the very loud acoustic noise from the scanner. This is particularly a problem during echo‐planar imaging, which is usually used for fMRI. We present a post‐hoc sound cancellation algorithm, and describe a Windows‐based tool that implements it. The tool is fast and operates with minimal user intervention. We evaluate cancellation performance in terms of the improvement in signal‐to‐noise ratio, and investigate the effect of the recording medium. A substantial improvement in audibility was obtained. Hum. Brain Mapping 24:299–304, 2005. © 2005 Crown Copyright
Brief breath holding may confound functional magnetic resonance imaging studies
Authors: Abbott David F. , Opdam Helen I. , Briellmann Regula S. , Jackson Graeme D. 
Published: January 2005

AbstractWe demonstrate that breath holding of short durations may confound functional magnetic resonance imaging (fMRI) studies. Some subjects may hold their breath for a short time during task performance, especially if the task is challenging. Breath holding may therefore need to be considered specifically when interpreting fMRI experiments. We studied the temporal and spatial characteristics of cerebral T2*‐weighted signal during short periods of breath holding by seven individuals in a 3‐tesla MR scanner. We demonstrate that breath‐holds as short as 3 s can result in regions of significant cerebral activation. More interestingly, we show that focal activation remains present when the data is analysed in a number of different ways, including analyses that correct for motion and model the task epoch as if it were 10 times longer than the actual breath‐hold length. These findings have potential relevance for many researchers carrying out fMRI studies. Hum. Brain Mapping 24:284–290, 2005. © 2005 Wiley‐Liss, Inc.
Visual evoked potentials may be recorded simultaneously with fMRI scanning: A validation study
Authors: Comi Eleonora , Annovazzi Pietro , Silva Ana Martins , Cursi Marco , Blasi Valeria , Cadioli Marcello , Inuggi Alberto , Falini Andrea , Comi Giancarlo , Leocani Letizia 
Published: January 2005

AbstractIntegrating electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data may help to optimize anatomical and temporal resolution in the investigation of cortical function. Successful removal of fMRI scanning artifacts from continuous EEG in simultaneous recordings has been reported. We assessed the feasibility of recording reliable visual evoked potentials (VEPs) during fMRI scanning using available artifact removing procedures. EEG during administration of visual stimuli was recorded using MRI‐compatible 32‐channel equipment in nine normal subjects (mean age, 23.9 ± 2.5 years), with and without fMRI acquisition. fMRI scanning and cardioballistographic artifacts were removed after subtraction of averaged artifact waveforms. Consistency between VEPs waveforms and of P1 and N1 peak latencies and amplitudes in the two conditions was assessed. Good correlation was found between VEP waveforms (Pearson's correlation coefficient: rP between 0.76–0.94 across subjects; P < 0.0001) and between latency or amplitude of P1 and N1 peaks (latencies: r = 0.7, P < 0.035; amplitudes: r > 0.65, P < 0.05; Spearman rank correlation coefficient) in the two recording conditions. No significant differences were found between P1 and N1 parameters in the two conditions (Wilcoxon signed rank test). Consistent VEP waveforms, latencies, and amplitudes with and without fMRI scanning indicate that reliable VEPs may be obtained simultaneously with fMRI recording. This possibility might be helpful by shortening recording times and reducing variability from learning, habituation, and fatigue phenomena from separate recordings for the integration of event‐related EEG and fMRI data. Hum. Brain Mapping 24:291–298, 2005. © 2005 Wiley‐Liss, Inc.
Difference in somatosensory evoked fields elicited by mechanical and electrical stimulations: Elucidation of the human homunculus by a noninvasive method
Authors: Inoue Ken , Shirai Takushi , Nakanishi Kazuyoshi , Hashizume Akira , Harada Toshihide , Mimori Yasuyo , Matsumoto Masayasu 
Published: January 2005

AbstractWe recently recorded somatosensory evoked fields (SEFs) elicited by compressing the glabrous skin of the finger and decompressing it by using a photosensor trigger. In that study, the equivalent current dipoles (ECDs) for these evoked fields appeared to be physiologically similar to the ECDs of P30m in median nerve stimulation. We sought to determine the relations of evoked fields elicited by mechanically stimulating the glabrous skin of the great toe and those of electrically produced P40m. We studied SEFs elicited by mechanical and electrical stimulations from the median and tibial nerves. The orientations of dipoles from the mechanical stimulations were from anterior‐to‐posterior, similar to the orientations of dipoles for P30m. The direction of the dipole around the peak of N20m from median nerve electrical stimulation was opposite to these directions. The orientations of dipoles around the peak of P40m by tibial nerve stimulation were transverse, whereas those by the compression and decompression stimulation of the toe were directed from anterior‐to‐posterior. The concordance of the orientations in ECDs for evoked fields elicited by mechanical and electrical stimulations suggests that the ECDs of P40m are physiologically similar to those of P30m but not to those of N20m. The discrepancy in orientations in ECDs for evoked field elicited by these stimulations in the lower extremity suggests that electrical and compression stimulations elicit evoked fields responding to fast surface rubbing stimuli and/or stimuli to the muscle and joint. Hum. Brain Mapping 24:274–283, 2005. © 2005 Wiley‐Liss, Inc.
Measuring the equilibrium effects of unemployment benefits dispersion
Authors: Vuuren Aico Van , Van Den Berg Gerard J. , Ridder Geert 
Published: January 2005

AbstractWe analyse the impact of unemployment benefits and minimum wages using an equilibrium search model which allows for dispersion of benefits and productivity levels, job‐to‐job transitions, and structural and frictional unemployment. The estimation method uses readily available aggregate data on marginal distributions of unemployment durations as well as wages and benefit levels. Different causes of structural and frictional unemployment are investigated. We investigate the efficiency of the imposition of a single benefit level for all household types and the introduction of a tax credit on earned income. Copyright © 2000 John Wiley & Sons, Ltd.
Formation of viscoelastic protein layers on polymeric surfaces relevant to platelet adhesion
Authors: Weber Norbert , Wendel Hans Peter , Kohn Joachim 
Published: January 2005

AbstractThe hemocompatibility of biomaterials is highly dependent on the adhesion and activation of platelets. Surface‐adsorbed fibrinogen has a dominant role in promoting platelet adhesion to artificial surfaces by binding glycoprotein IIb‐IIIa (GPIIb‐IIIa), the major platelet membrane receptor. Using quartz crystal microbalance with dissipation monitoring (QCM‐D), we have investigated the material‐dependent binding kinetics of purified GPIIb‐IIIa to polymer‐adsorbed fibrinogen. The following ranking of polymer‐adsorbed mass (fibrinogen and GPIIb‐IIIa) to test polymers could be established: poly[desaminotyrosyl‐tyrosine ethyl (DTE) carbonate]/poly(lactide‐co‐glycolide) > poly[DTE co‐5% poly(ethylene glycol) carbonate]. The QCM‐D fibrinogen adsorption data were confirmed using an immunofluorescence assay. A synthetic RGD‐containing peptide, but not a control peptide, inhibited GPIIb‐IIIa binding to polymer‐adsorbed fibrinogen, demonstrating the specificity of binding. Importantly, the binding efficiency of purified GPIIb‐IIIa to polymer‐adsorbed fibrinogen correlated with increased platelet adhesion in an in vitro model. Theoretical simulations using a Voight‐based model provided quantitative data on the thickness and viscoelastic properties of the polymer‐adsorbed protein layers. The precision of the modeling technique was limited with respect to the shear moduli values, leading to large variations. However, the other modeling parameters showed reproducible results. The thickness of both protein layers was polymer‐dependent and ranged from 5 to 35 nm and the viscosity from 0.001 to 0.005 kg/ms, whereas the protein layer densities showed little differences between the test polymers. These results suggest that material‐dependent changes in the thickness and viscoelastic properties of adsorbed fibrinogen‐GPIIb‐IIIa layers are crucial factors in the binding behavior of platelets to biomaterials. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 420–427, 2005
Nanoporous delivery system to treat osteomyelitis and regenerate bone: Gentamicin release kinetics and bactericidal effect
Authors: El‐Ghannam Ahmed , Ahmed Karima , Omran Maha 
Published: January 2005

AbstractConventional treatment of osteomyelitis involves the repeated surgical removal of dead bone tissue coupled with repeated irrigation of the wound and prolonged systemic administration of antibiotics. Therapy of bone infections could easily last the rest of the patient's life because of the poor accessibility of the infection site by common systemically administered antibiotics. The objective of the present study is to develop a novel bone bioactive resorbable nanocomposite that can serve as a delivery system for antibiotics. We synthesized three different samples of porous bioactive resorbable silica–calcium phosphate nanocomposite (C3S1, C1S1, and C1S3) that has the ability to provide a sustained release of effective dose of gentamicin for 28 days. Porosity measurements showed that the average pore diameter of C3S1, C1S1, and C1S3 samples is 44.8, 54.4, and 70.9 nm, respectively. Moreover, the silica‐rich composite (C1S3) is characterized by a significantly higher surface area (155.8 m2/g) than the silica‐poor samples (C3S1) (42.9 m2/g). For all samples, the release profile study showed initial burst release followed by a sustained release of gentamicin. The released gentamicin has a strong inhibitory effect on Staphylococcus aureus bacteria. In addition FTIR analysis showed the formation of a biological apatite layer on the material surface after 24 h of immersion in simulated body fluid. Results of the study suggest that the silica–calcium phosphate nanocomposite can serve as a delivery vehicle for gentamicin to treat osteomyelitis and regenerate bone. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater