bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Determination of Ascorbic Acid, Dopamine and Uric Acid at Pt Nanoparticles Decorated Multiwall Carbon Nanotubes Modified GCE
Authors: Dursun Zekerya , Gelmez Buket 
Published: March 2010

AbstractA modified electrode was fabricated by electrochemically deposition of Pt nanoparticles on the multiwall carbon nanotube covered glassy carbon electrode (Pt nanoparticles decorated MWCNT/GCE). A higher catalytic activity was obtained to electrocatalytic oxidation of ascorbic acid, dopamine, and uric acid due to the enhanced peak current and well‐defined peak separations compared with both, bare and MWCNT/GCE. The electrode surfaces were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). Individual and simultaneous determination of AA, DA, and UA were studied by differential pulse voltammetry. The detection limits were individually calculated for ascorbic acid, dopamine, and uric acid as being 1.9×10−5 M, 2.78×10−8 M, and 3.2×10−8 M, respectively. In simultaneous determination, LODs were calculated for AA, DA, and UA, as of 2×10−5 M, 4.83×10−8 M, and 3.5×10−7 M, respectively.
A Comparative Study of the Modification of Gold and Glassy Carbon Surfaces with Mixed Layers of In Situ Generated Aryl Diazonium Compounds
Authors: Liu Guozhen , Chockalingham Muthukumar , Khor Sook Mei , Gui Alicia L. , Gooding J. Justin 
Published: March 2010

AbstractIn situ generated aryl diazonium cations were synthesized in the electrochemical cell by reaction of the corresponding amines with NaNO2 in aqueous HCl. This paper reports a study of the formation of mixed layers from in situ generated aryl diazonium cations. Firstly, glassy carbon (GC) and gold electrode surfaces were modified with five single in situ generated aryl diazonium salts to obtain their corresponding reductive potential followed by the modification of GC and gold surfaces with eight binary mixed layers of in situ generated aryl diazonium salts. The difference between GC and gold surfaces in terms of in situ formation of two‐component aryl diazonium salt films was compared. The behavior of the mixed layers formed from in situ generated aryl diazonium salts relative to diazonium salts that were pre‐synthesized prior to surface modification was also investigated. Cyclic voltammetry and X‐ray photoelectron spectroscopy were used to characterize the resulting modified GC and gold surfaces. It is found that for some aryl diazonium salts the potential at which reductive adsorption is achieved on gold and GC surfaces is significantly different. For the eight sets of binary mixed layers, the species with more anodic potential are more difficult to attach to the both GC and gold surfaces. The behavior of the mixed layers formed from in situ generated aryl diazonium salts and the pre‐synthesized diazonium salts is similar; which emphasizes the advantage of the in situ approach without any apparent difference in behavior to the presynthesized diazonium salts.
Evaluating Enzyme Cascades for Methanol/Air Biofuel Cells Based on NAD+‐Dependent Enzymes
Authors: Addo Paul K. , Arechederra Robert L. , Minteer Shelley D. 
Published: March 2010

AbstractPrevious work by the group has entailed encapsulating enzymes in polymeric micelles at bioelectrode surfaces by utilizing hydrophobically modified Nafion membranes, which are modified in order to eliminate the harsh acidity of Nafion while tailoring the size of the polymer micelles to optimize for the encapsulation of an individual enzyme. This polymer encapsulation has been shown to provide high catalytic activity and enzyme stability. In this study, we employed this encapsulation technique in developing a methanol/air biofuel cell through the combined immobilization of NAD+‐dependent alcohol dehydrogenase (ADH), aldehyde dehydrogenase (AldDH) and formate dehydrogenase (FDH) within a tetrabutylammonium bromide (TBAB) modified Nafion to oxidize methanol to carbon dioxide with poly(methylene green) acting as the NADH electrocatalyst electropolymerized on the surface of the electrode. The methanol biofuel/air cell resulted in a maximum power density of 261±7.6 μW/cm2 and current density of 845±35.5 μA/cm2. This system was characterized for the effects of degree of oxidation, temperature, pH, and concentration of fuel and NAD.
Separation and quantification of double‐ and triple‐layered rotavirus‐like particles by CZE
Authors: Castro‐Acosta Ricardo M. , Revilla Alma L. , Ramírez Octavio T. , Palomares Laura A. 
Published: March 2010

AbstractVirus‐like particles have been successfully used as safe vaccines, as their structure is identical to their native counterparts but devoid of the viral genetic material. However, production of these complex structures is not easy, as recombinant proteins must assemble into virus‐like particles. Techniques to differentiate assembled and soluble proteins, as well as assembly intermediaries often present in a sample, are required. An example of complex virus‐like particles mixture occurs when rotavirus proteins are recombinantly expressed. Rotavirus‐like particles (RLP) can be single (sl), double (dl), or triple layered (tl). The use of RLP preparations as vaccines requires their complete characterization, including separation and quantification of each RLP in a sample. In this work, CZE was evaluated for the separation and quantification of dl and triple‐layered rotavirus‐like particles (tlRLP). A fused‐silica capillary with a deoxycholate running buffer efficiently separated dl and tlRLP in RLP preparations, as they migrated in two discrete peaks with electrophoretic mobilities of 1.24±0.04 and 2.95±0.03 Ti, respectively. Standard curves for dl and tlRLP were generated, and the response was linearly proportional to analyte concentration. The methodology developed was quantitative, specific, accurate, precise, and reproducible. CZE allowed the quantitative characterization of RLP preparations, which is required for evaluation of immunogens, for process development, and for quality control protocols.
Chemical and energetic characterization of species with a high‐biomass production: Fractionation of their components
Authors: Franscisco López , Juan Carlos García , Antonio Pérez , M. Javier Feria , Minerva A.M. Zamudio , Gil Garrote 
Published: March 2010

AbstractIn this work, we determined the properties of cellulose pulp and paper from six different lignocellulosic materials [Eucalyptus globulus, Arundo donax, Leucaena diversifolia, Paulownia fortunei, sunflower stalks, and Chamaecytisus proliferus (tagasaste)], as well as the heating value and chemical composition of their autohydrolysis liquor, with a view to assessing their potential for the obtainment of energy, sugars, and other chemical products. An integral fractionation method based on autohydrolysis and organosolv delignification was used for this purpose. L. diversifolia, P. fortunei, a Paulownia “trihybrid” consisting of elongata, tormentosa, and fortunei varieties; sunflower stalks; and C. proliferus exhibited holocellulose, glucan, xylan, and acetyl group contents similar to, or higher than, those of E. globulus, A. donax, and various other lignocellulosic materials. The amounts of oligomers extracted from C. proliferus, P. fortunei, L. diversifolia, and sunflower stalks at the highest temperatures studied exceeded those provided by eucalyptus. Sequential autohydroysis and organosolv delignification of L. diversifolia and C. proliferus provided cellulose pulp with an acceptable kappa number and paper sheets with good strength‐related properties. P. fortunei was the most interesting raw material among those tested; in fact, it provided ethanol pulp with a lignin content of 3.7− 15.3% and a kappa number of 40.5–74.1 after autohydrolysis at 190°C, and paper with a tensile index of 17.0–28.9 kN m/kg. These properties are similar to those of pulp and paper from eucalyptus wood. In addition, P. fortunei exhibited the highest heating value among the studied materials (4683.8 cal/g). © 2010 American Institute of Chemical Engineers Environ Prog, 2010
A dynamic temperature model of mine water‐fed raceways used for microalgae biofuel production
Authors: Shang H. , Scott J.A. , Ross G.M. , Shepherd S. 
Published: March 2010

AbstractThe mining industry is an extremely high consumer of energy, much of which is sourced from fossil fuels. The industry also generates outflows of “waste” energy in discharged gas, air, and water streams. Both the dependence on, and the environmental impacts of, fossil fuels could be reduced by on‐site energy recovery schemes that make use of both waste energy and the large tracts of the otherwise marginal or nonproductive land that mines sites create and occupy. One such possibility lies in the potential for on‐site use of the warm mine water from dewatering in raceways to support microalgae growth for biodiesel production. Mines are, however, often located in remote regions that can experience a significant range in seasonal ambient temperatures. In this article, a model that can be used to estimate the dynamic impact of a wide range of annual climatic conditions on the temperature of a specific volume of mine water flowing along a microalgae raceway is reported. © 2010 American Institute of Chemical Engineers Environ Prog, 2010
Experimental field assessment of suspended sediment pathways for characterizing hydraulic habitat
Authors: Harvey Gemma L. , Clifford Nicholas J. 
Published: March 2010

AbstractThe distribution of particulate matter within river channels, including sediments, nutrients and pollutants, is fundamental to the survival of aquatic organisms. However, the interactions between flow and sediment transport at the patch scale of river systems represents an under‐researched component of physical habitat studies, particularly those concerning the characterization of ‘physical biotopes’ (riffles, runs, pools, glides). This paper describes a field methodology for exploring the transfer of particulate matter at small scales within river channels, which may be used to aid hydraulic habitat characterization. The field protocol combines field measurement of high frequency flow properties, to characterize hydraulic habitat units, and deployment of spatial arrays of turbidity probes, to detect the passage of artificially‐induced sediment plumes through different biotope units. Sediment plumes recorded by the probes are analysed quantitatively in the manner of the flood hydrograph, and qualitative inferences are made on the dominant mixing processes operating within different parts of the channel. Relationships between the nature of spatio‐temporal hydraulic variations within glide, riffle and pool biotopes, and the character and mixing behaviour of sediment plumes within these habitat units are identified. Results from these preliminary experiments suggest that investigating and characterizing the transfer and storage of sediments, nutrients and pollutants within and between different biotopes is a viable avenue for further research, with potential to contribute to improved physical habitat characterization for river management and habitat restoration. The experiments are also an illustration of the value of neglected synergies between process geomorphology, ecology and river hydraulics. Copyright © 2010 John Wiley & Sons, Ltd.
New proposals for the quantification of qualitative survey data
Authors: Proietti Tommaso , Frale Cecilia 
Published: March 2010

AbstractIn this paper we propose and evaluate two new methods for the quantification of business surveys concerning the qualitative assessment of the state of the economy. The first is a nonparametric method based on the spectral envelope, originally proposed by Stoffer, Tyler and McDougall (Spectral analysis for categorical time series: scaling and the spectral envelope, Biometrika 80: 611–622) to the multivariate time series of the counts in each response category. Secondly, we fit by maximum likelihood a cumulative logit unobserved components models featuring a common cycle. The conditional mean of the cycle, which can be evaluated by importance sampling, offers the required quantification. We assess the validity of the two methods by comparing the results with a standard quantification based on the balance of opinions and with a quantitative economic indicator. Copyright ? 2010 John Wiley & Sons, Ltd.
Anterior cingulate activity and the self in disorders of consciousness
Authors: Qin Pengmin , Di Haibo , Liu Yijun , Yu Senming , Gong Qiyong , Duncan Niall , Weng Xuchu , Laureys Steven , Northoff Georg 
Published: March 2010

AbstractObjectives: The aim of this study was to investigate the relationship between medial cortical activation and the presence of self and consciousness in healthy subjects and patients with vegetative state and minimally conscious state using functional magnetic resonance imaging (fMRI). Experiment design: We first conducted two fMRI experiments in healthy subjects to identify brain regions specifically associated with self‐perception through the use of different auditory stimuli that had different grades of self‐relatedness. We then applied these regions as functional localizers to examine the relationship between neural activity changes during self‐relatedness and consciousness level in the patients with disorders of consciousness (DOC). Principal observations: We demonstrated recruitment of various anterior medial cortical regions including the anterior cingulate cortex (ACC) in healthy subjects during auditory perception of self‐related stimuli. We further showed that patients with DOC showed signal changes in the ACC during auditory perception of self‐related stimuli. Finally, it was shown that these signal changes correlate with the level of consciousness in the patients with DOC. Conclusion: The degree of consciousness in patients with DOC was correlated with neural activity in the ACC induced by self‐related stimuli. Our results not only shed light on the pathophysiology of DOC, but may also suggest a useful neural, and thus diagnostic, marker of the dysfunction of consciousness in vegetative patients. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.
Dehydration affects brain structure and function in healthy adolescents
Authors: Kempton Matthew J. , Ettinger Ulrich , Foster Russell , Williams Steven C.R. , Calvert Gemma A. , Hampshire Adam , Zelaya Fernando O. , O'Gorman Ruth L. , McMorris Terry , Owen Adrian M. , Smith Marcus S. 
Published: March 2010

AbstractIt was recently observed that dehydration causes shrinkage of brain tissue and an associated increase in ventricular volume. Negative effects of dehydration on cognitive performance have been shown in some but not all studies, and it has also been reported that an increased perceived effort may be required following dehydration. However, the effects of dehydration on brain function are unknown. We investigated this question using functional magnetic resonance imaging (fMRI) in 10 healthy adolescents (mean age = 16.8, five females). Each subject completed a thermal exercise protocol and nonthermal exercise control condition in a cross‐over repeated measures design. Subjects lost more weight via perspiration in the thermal exercise versus the control condition (P < 0.0001), and lateral ventricle enlargement correlated with the reduction in body mass (r = 0.77, P = 0.01). Dehydration following the thermal exercise protocol led to a significantly stronger increase in fronto‐parietal blood‐oxygen‐level‐dependent (BOLD) response during an executive function task (Tower of London) than the control condition, whereas cerebral perfusion during rest was not affected. The increase in BOLD response after dehydration was not paralleled by a change in cognitive performance, suggesting an inefficient use of brain metabolic activity following dehydration. This pattern indicates that participants exerted a higher level of neuronal activity in order to achieve the same performance level. Given the limited availability of brain metabolic resources, these findings suggest that prolonged states of reduced water intake may adversely impact executive functions such as planning and visuo‐spatial processing. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.
A phase synchrony measure for quantifying dynamic functional integration in the brain
Authors: Aviyente Selin , Bernat Edward M. , Evans Westley S. , Sponheim Scott R. 
Published: March 2010

AbstractThe temporal coordination of neural activity within structural networks of the brain has been posited as a basis for cognition. Changes in the frequency and similarity of oscillating electrical potentials emitted by neuronal populations may reflect the means by which networks of the brain carry out functions critical for adaptive behavior. A computation of the phase relationship between signals recorded from separable brain regions is a method for characterizing the temporal interactions of neuronal populations. Recently, different phase estimation methods for quantifying the time‐varying and frequency‐dependent nature of neural synchronization have been proposed. The most common method for measuring the synchronization of signals through phase computations uses complex wavelet transforms of neural signals to estimate their instantaneous phase difference and locking. In this article, we extend this idea by introducing a new time‐varying phase synchrony measure based on Cohen's class of time–frequency distributions. This index offers improvements over existing synchrony measures by characterizing the similarity of signals from separable brain regions with uniformly high resolution across time and frequency. The proposed measure is applied to both synthesized signals and electroencephalography data to test its effectiveness in estimating phase changes and quantifying neural synchrony in the brain. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.
Frontal and parietal contributions to arithmetic fact retrieval: A parametric analysis of the problem‐size effect
Authors: Jost Kerstin , Khader Patrick H. , Burke Michael , Bien Siegfried , Rösler Frank 
Published: March 2010

AbstractThe goal of the present study was to investigate the neuroanatomical basis of arithmetic fact retrieval. The rationale was that areas playing a crucial role in arithmetic fact retrieval should show a systematic increase of activation with increasing retrieval effort. To achieve this goal, we utilized the problem‐size effect as this is known to be systematically related to retrieval effort. In contrast to many previous studies, we here took a parametric approach to account for the continuous increase of retrieval effort with problem size. BOLD signals were modeled with problem size as parametric regressor and negative slow waves of the EEG were categorized into six levels of problem size. The fMRI data showed that activation in the angular gyrus and ACC/SMA increased parametrically with problem size. The ERP data showed a systematic amplitude increase with increasing problem size, especially at fronto‐central electrodes. Consistent with the fMRI data, source modeling localized this effect to the ACC. While these findings support previous notions about the crucial role of the angular gyrus during fact retrieval, they also provide evidence that the medial frontal cortex is involved when single‐digit multiplications are solved. Thus, both parietal and frontal structures seem to be integral parts of a system that enables and controls arithmetic fact retrieval. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.
Genetic variation in G72 correlates with brain activation in the right middle temporal gyrus in a verbal fluency task in healthy individuals
Authors: Krug Axel , Markov Valentin , Krach Sören , Jansen Andreas , Zerres Klaus , Eggermann Thomas , Stöcker Tony , Shah N Jon , Nöthen Markus M , Georgi Alexander , Strohmaier Jana , Rietschel Marcella , Kircher Tilo 
Published: March 2010

AbstractThe D‐amino acid oxidase activator gene (G72) has been found associated with several psychiatric disorders such as schizophrenia, major depression, and bipolar disorder. Impaired performance in verbal fluency tasks is an often replicated finding in the mentioned disorders. In functional neuroimaging studies, this dysfunction has been linked to signal changes in prefrontal and lateral temporal areas and could possibly constitute an endophenotype. Therefore, it is of interest whether genes associated with the disorders, such as G72, modulate verbal fluency performance and its neural correlates. Ninety‐six healthy individuals performed a semantic verbal fluency task while brain activation was measured with functional MRI. All subjects were genotyped for two single nucleotide polymorphisms (SNP) in the G72 gene, M23 (rs3918342) and M24 (rs1421292), that have previously shown association with the above‐mentioned disorders. The effect of genotype on brain activation was assessed with fMRI during a semantic verbal fluency task. Although there were no differences in performance, brain activation in the right middle temporal gyrus (BA 39) and the right precuneus (BA 7) was positively correlated with the number of M24 risk alleles in the G72 gene. G72 genotype does modulate brain activation during language production on a semantic level in key language areas. These findings are in line with structural and functional imaging studies in schizophrenia, which showed alterations in the right middle temporal gyrus. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.
A new tablet for writing and drawing during functional MRI
Authors: Tam Fred , Churchill Nathan W. , Strother Stephen C. , Graham Simon J. 
Published: March 2010

AbstractWriting and drawing are understudied with fMRI, partly for lack of a device that approximates these behaviors well while supporting task feedback and quantitative behavioral logging in the confines of the magnet. Consequently, we developed a tablet based on touchscreen technology that is accurate, reliable, relatively inexpensive, and fMRI compatible. After confirming fMRI compatibility, we conducted preliminary fMRI experiments examining the neural correlates of a widely used pen‐and‐paper neuropsychological assessment, the trail making test. In two subjects, we found left hemisphere frontal lobe activations similar to the major results of a previous group study, and we also noted individual differences mostly in the right hemisphere. These results demonstrate the utility of the new tablet for adaptations of pen‐and‐paper tests and suggest possible uses of the tablet for longitudinal, within‐subjects studies of disease or therapy. We also discuss using the tablet for several other types of tests requiring many, continuous, or two‐dimensional responses that were previously very difficult to perform during fMRI. Hum Brain Mapp, 2011. © 2010 Wiley‐Liss, Inc.