bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Quantification of Heavy Metals Using a Solid State Potentiometric Sensor Array
Authors: Gismera Ma Jesús , Arias Sandra , Sevilla Ma Teresa , Procopio Jesús R. 
Published: February 2009

AbstractA potentiometric sensor array of four nonspecific electrodes with solid‐state membranes is developed and tested for simultaneous analysis of copper(II), mercury(II), and silver(I) ions. The cross‐sensitivity responses of the sensors for these ions are evaluated. The array potentiometric signals are processed by partial least‐squares regression (PLS) and back propagation artificial neural networks (ANN) to determinate analyte concentrations. The ANN configuration is optimized and two different training algorithms of the ANN are also evaluated. Best results are obtained when the potentiometric sensors are activated and the data are processed using ANN and the gradient descent adaptive algorithm. The system is used to quantify these heavy metals in synthetic samples and in dental amalgams with successful results.
Thionicotinamide SAM on Gold: Adsorption Studies and Electroactivity
Authors: de Freitas Paulo Tércio , de Oliveira Pinheiro Solange , Da Silva Maria Aparecida S. , de França Lopes Luiz Gonzaga , Pinheiro Lucidalva S. , Aquino Gil F. A. , Temperini Márcia Laudelina Arruda , de Lima Neto Pedro , Diógenes Izaura Cirino Nogueira 
Published: February 2009

AbstractSTM and impedance results of the self‐assembled monolayer (SAM) formed with thionicotinamide (TNA) on gold indicate the presence of defects that increase with the immersion time of the electrode in the TNA solution affecting the SAM electroactivity toward the electron transfer reaction of the cytochrome c metalloprotein and [Fe(CN)6]4− and [Ru(NH3)6]3+ complexes. It was observed that this electroactivity was also affected by the pH of the electrolyte solution. SERS and STM data indicate sulfur coordination to the surface with contribution of the NH2 group. From the dependence of the TNA surface coverage on the temperature and concentration in solution, thermodynamic parameters of adsorption were determined.
Green Approaches to Field Nitrate Analysis: An Electroanalytical Perspective
Authors: Desai Radha , Marti Villalba Maria , Lawrence Nathan S. , Davis James 
Published: February 2009

AbstractThe different approaches that have been taken in the development of analytical methods for the determination of nitrate within the field are reviewed. The emphasis has been placed on providing a critical appraisal of the chemistry that underpins current commercial systems and the need to remove the dependence on heavy metal and concentrated acid components. The search for more environmentally acceptable and user friendly systems has long been pursued and the present communication seeks to explore the recent development in portable testing technologies and how they might evolve in the future. In particular, the role of electrochemical techniques in the latter are investigated and their potential application compared and contrasted with the more traditional wet chemical detection strategies.
Localized Deposition of Chitosan as Matrix for Enzyme Immobilization
Authors: Chen Po‐Chung , Chen Richie L. C. , Cheng Tzong‐Jih , Wittstock G. 
Published: February 2009

AbstractA local electrodeposition method was developed for chitosan by exploiting a pH gradient between a macroscopic electrode (the support) and a much smaller counter electrode. The deposition was confined either by using the direct mode of scanning electrochemical microscopy (SECM) or by performing the deposition in channels of a microfluidic network. The roughness was characterized by noncontact scanning force microscopy. The availability of amino groups at the surface of the microstructures was visualized after labeling by confocal laser scanning microscopy. The enzyme glucose oxidase could be entrapped during the electrochemical deposition and showed activity as seen by SECM images.
Single‐nucleotide polymorphism typing based on pyrosequencing chemistry and acryl‐modified glass chip
Authors: Huang Huan , Wu Haiping , Xiao Pengfeng , Zhou Guohua 
Published: February 2009

AbstractA new method (termed as “chip‐BAMPER” (bioluminometric assay coupled with modified primer extension reactions)) for single‐nucleotide polymorphism (SNPs) genotyping was developed by pyrosequencing chemistry coupled with hydrogel chip immobilized with single‐stranded target DNAs. The method is based on allele‐specific extension reaction, which is switched by the base type in the 3′ end of allele‐specific primers. A genotype is determined by comparing the light intensity from a pair of gel pads, and the specificity is improved by introducing an artificially mismatched base at the third position upstream from the 3′ end of the allele‐specific primer. The big problem of chip‐BAMPER is the ultra‐high background of the detection mixture because apyrase could not be used. Here, we successfully prepared and used beaded apyrase, which can be removed from the detection mixture before sample typing, to decrease the high background due to adenosine 5′‐triphosphate and inorganic pyrophosphate or sodium pyrophosphate decahydrate contamination. Unlike gel‐based pyrosequencing, chip‐BAMPER is highly sensitive because many bases are extended at a time in one extension reaction. Usually, less than 0.25 μL of PCR products can give a successful genotyping. To evaluate the method, four SNPs, OLR1‐C15577T, OLR1‐C14417G, PPARG‐Pro12Ala, and PPARG‐C2821T, were detected. To avoid the crosstalk between two adjacent spots in a gel‐chip, mineral oil was dispensed to coat the gel‐chip for physically separating two spots. It is shown that this new strategy of SNP typing based on the acryl‐modified glass chip is highly sensitive, simple, inexpensive, and easy to be automated. It can be used for various applications of DNA analysis at a relative high‐throughput.
Development and evaluation of a model for soil–air fluidized bed rheological behavior
Authors: Fox David M. , Lee Joon Sang 
Published: February 2009

AbstractThe ground vehicle mine blast mitigation problem represents a research topic that has recently been generating a very high level of interest and activity. Many aspects of the physics of the problem have been extensively researched. One area that has been neglected, however, is that aspect of the blast threat that relates to the rheology and flow, subsequent to ignition of the explosive, of the relatively energetic mixture of air and soil, sometimes referred to as ejecta.Methods developed for the study of fluidized beds that are used in, e.g. the chemical and power generation process industries, were adapted in order to more clearly define the rheology of air–glass bead mixtures and also of air–soil mixtures that comprise the ejecta. Continuity and momentum balance equations developed for fluidized beds were adapted, using physical properties of glass beads and soils, into a form relates to the properties of mine blast ejecta.These equations were then discretized and solved, for a relatively simple geometry, in order to validate the model and gain a general sense of the flow behavior of particle–air blends. Parametric studies were performed to estimate the variation of the rheology of the air–particle mixtures as a function of the particle diameter and the sphericity of the particles. Finally, the flow properties of a couple of real soils were investigated via application of the two‐phase flow model. Copyright © 2009 John Wiley & Sons, Ltd.
Moving mesh methods for Boussinesq equation
Authors: Wan‐Lung Lee , Tan Zhijun 
Published: February 2009

AbstractThe Boussinesq equation is a challenging problem both analytically and numerically. Owing to the complex dynamic development of small scales and the rapid loss of solution regularity, the Boussinesq equation pushes any numerical strategy to the limit. With uniform meshes, the amount of computational time is too large to enable us to obtain useful numerical approximations. Therefore, developing effective and robust moving mesh methods for these problems becomes necessary. In this work, we develop an efficient moving mesh algorithm for solving the two‐dimensional Boussinesq equation. Our moving mesh algorithm is an extension of Tang and Tang (SIAM J. Numer. Anal. 2003; 41:487–515) for hyperbolic conservation laws and Zhang and Tang (Commun. Pure Appl. Anal. 2002; 1:57–73) for convection‐dominated equations. Several numerical fluxes (Riemann Solvers and Numerical Methods for Fluid Dynamics: A Practical Introduction (2nd edn). Springer: Berlin, 1999; WASCOM 99”: 10th Conference on Waves and Stability in Continuous Media, Porto Ercole, Italy, 1999; 257–264; High‐order Methods for Computational Physics. Springer: Berlin, 1999; 439–582; J. Sci. Comput. 1990; 5:127–149; SIAM J. Numer. Anal. 2003; 41:487–515; Commun. Pure Appl. Anal. 2002; 1:57–73) are also discussed. Numerical results demonstrate the advantage of our moving mesh method in resolving the small structures. Copyright © 2009 John Wiley & Sons, Ltd.
Flow division at a channel crossing with subcritical or supercritical flow
Authors: Li C. W. , Zeng C. 
Published: February 2009

AbstractThe passage of an extreme storm over an urban area can lead to the flooding of the streets if the rainfall intensity exceeds the design value and/or the drainage system is not functional. The study of flow distribution in street networks thus is important for the design of flood protection measures. The flow distribution is affected by the junction flow characteristics, inflow discharges and downstream water depths. To reduce the degree of empiricism, a 3D Reynolds‐averaged Navier–Stokes equations model has been implemented in this study to investigate the flow phenomena in a cross junction. The Spalart–Allmaras model is used for turbulence closure. The numerical model utilizes the split‐operator approach, in which the advection, diffusion and pressure propagations are solved separately. The numerical model predicts accurately the flow distribution in a channel crossing under different subcritical flow conditions, for which experimental data are available. Recirculation zones exist at both the downstream channels and the associated contraction coefficient varies linearly with the ratio of the discharges at the two inlets. Secondary currents are apparent for the flow with strong asymmetric outlet conditions. Under supercritical inflow conditions, the model reproduces the hydraulic jump and hydraulic drop phenomena and predicts accurately the relationship between the input power ratio and the outflow discharge ratio of the street crossing. Copyright © 2009 John Wiley & Sons, Ltd.
Increase in gene dosage is a mechanism of HIF‐1α constitutive expression in head and neck squamous cell carcinomas
Authors: Secades Pablo , Rodrigo Juan Pablo , Hermsen Mario , Alvarez Cesar , Suarez Carlos , Chiara María‐Dolores 
Published: February 2009

AbstractThe HIF‐1α protein plays a key role in the cellular response to hypoxia via transcriptional regulation of genes involved in erythropoiesis, angiogenesis, and metabolism. Overexpression of HIF‐1α is commonly found in solid tumors in significant association with increased patient mortality and resistance to therapy. The predominant mode of HIF‐1α regulation by hypoxia occurs at the level of protein stability. In addition to hypoxia, HIF‐1α protein stability and synthesis is regulated by nonhypoxic signals such as inactivation of tumor suppressors and activation of oncogenes. Here, we show that an increase in gene dosage may contribute to HIF‐1α mRNA and protein overexpression in a nonhypoxic environment in head and neck squamous cell carcinomas (HNSCC). Increased HIF‐1α gene dosage was found in one out of five HNSCC‐derived cell lines and three out of 27 HNSCC primary tumors. Significantly, increased gene dosage in those samples was associated with high HIF‐1α mRNA and protein levels. Normoxic overexpression of HIF‐1α protein in HNSCC‐derived cell lines was also paralleled by higher expression levels of HIF‐1α target genes. Array CGH analysis confirmed the copy number increase of HIF‐1α gene and revealed that the gene is contained within a region of amplification at 14q23‐q24.2 both in the cell line and primary tumors. In addition, FISH analysis revealed the presence of 11–13 copies on a tetraploid background in SCC2 cells. These data suggest that increased HIF‐1α gene dosage is a mechanism of HIF‐1α protein overexpression in HNSCC that possibly prepares the cells for a higher activity in an intratumoral hypoxic environment. © 2009 Wiley‐Liss, Inc.
Genomic imbalances in rhabdomyosarcoma cell lines affect expression of genes frequently altered in primary tumors: An approach to identify candidate genes involved in tumor development
Authors: Missiaglia Edoardo , Selfe Joanna , Hamdi Mohamed , Williamson Daniel , Schaaf Gerben , Fang Cheng , Koster Jan , Summersgill Brenda , Messahel Boo , Versteeg Rogier , Pritchard‐Jones Kathy , Kool Marcel , Shipley Janet 
Published: February 2009

AbstractRhabdomyosarcomas (RMS) are the most common pediatric soft tissue sarcomas. They resemble developing skeletal muscle and are histologically divided into two main subtypes; alveolar and embryonal RMS. Characteristic genomic aberrations, including the PAX3‐ and PAX7‐FOXO1 fusion genes in alveolar cases, have led to increased understanding of their molecular biology. Here, we determined the effect of genomic copy number on gene expression levels through array comparative genomic hybridization (CGH) analysis of 13 RMS cell lines, confirmed by multiplex ligation‐dependent probe amplification copy number analyses, combined with their corresponding expression profiles. Genes altered at the transcriptional level by genomic imbalances were identified and the effect on expression was proportional to the level of genomic imbalance. Extrapolating to a public expression profiling dataset for 132 primary RMS identified features common to the cell lines and primary samples and associations with subtypes and fusion gene status. Genes identified such as CDK4 and MYCN are known to be amplified, overexpressed, and involved in RMS tumorigenesis. Of the many genes identified, those with likely functional relevance included CENPF, DTL, MYC, EYA2, and FGFR1. Copy number and expression of FGFR1 was validated in additional primary material and found amplified in 6 out of 196 cases and overexpressed relative to skeletal muscle and myoblasts, with significantly higher expression levels in the embryonal compared with alveolar subtypes. This illustrates the ability to identify genes of potential significance in tumor development through combining genomic and transcriptomic profiles from representative cell lines with publicly available expression profiling data from primary tumors. © 2009 Wiley‐Liss, Inc.
Association analysis of the COMT/MTHFR genes and geriatric depression: An MRI study of the putamen
Authors: Pan Chih‐Chuan , McQuoid Douglas R. , Taylor Warren D. , Payne Martha E. , Ashley‐Koch Allison , Steffens David C. 
Published: February 2009

AbstractObjectiveCatechol‐O‐Methyltransferase (COMT) and Methylenetetrahydrofolate reductase (MTHFR) had been reported to relate to depression but with inconsistent results. The basal ganglia are also important in the pathophysiology of affective disorder via connections with limbic system and prefrontal cortex. The authors examined the relationship between an interaction of COMT/MTHFR polymorphisms and volumes of putamen in depressed and nondepressed elders.MethodsParticipants included 170 depressed and 83 nondepressed subjects aged 60 years or older. Subjects completed cross‐sectional assessments, including clinical evaluation, brain magnetic resonance imaging (MRI) scan, and COMT Val158Met and MTHFR C677T genotyping. Putamen volumes were measured using 1.5‐Tesla whole‐body MRI system. Statistical models examined the relationship between COMT/MTHFR genotype, proportional volumes of putamen and depression while controlling for age and sex.ResultsAfter controlling for covariates, among depressed subjects with MTHFR C/C, both the right and left putamen had smaller volumes as the number of COMT 158Val increased. The left putamen volumes of depressed subjects with COMT Met/Met were smaller as the number of MTHFR 677T increased compared to nondepressed subjects.ConclusionsOur findings do not support a major role for COMT or MTHFR alone. However, an epigenetic interaction of COMT Val158Met and MTHFR C677T polymorphisms may contribute to putamen volumes differences between depressed and nondepressed subjects. Further studies with a larger sample size are necessary to support a genetically based role for basal ganglia structures in the etiopathogenesis of depression. Copyright © 2009 John Wiley & Sons, Ltd.
Investigation of dopamine receptors in susceptibility to behavioural and psychological symptoms in Alzheimer's disease
Authors: Pritchard Antonia L. , Ratcliffe Laura , Sorour Eman , Haque Sayeed , Holder Roger , Bentham Peter , Lendon Corinne L. 
Published: February 2009

AbstractObjectiveAlzheimer's disease (AD) patients commonly suffer from behavioural and psychological symptoms of dementia (BPSD). A genetic component to the development of BPSD in AD has been supported. Polymorphisms within dopamine receptors DRD1, DRD2, DRD3 and DRD4 have previously been investigated in a few interesting studies that are reviewed here and extended using our patient cohort.MethodsOur large cohort of 395 probable AD patients had longitudinal information on the BPSD (Neuropsychiatric Inventory), which was used to dichotomise patients into whether they had ever suffered from a given symptom within the study period, or not. These measures were related to the DRD1 (A‐48G), DRD2 (ser311cys; C‐ins/del), DRD3 (ser9gly) and DRD4 (VNTR) genotype and allele frequencies.ResultsAssociations were revealed between DRD3 and elation, and between DRD4 with agitation/aggression and with depression; however, these findings do not remain significant after correction for multiple testing. No associations were found with the other genetic variants and these symptoms and no associations were observed between any of the polymorphic variants examined and delusions, hallucinations, psychosis and aberrant motor behaviour.ConclusionOur data, in combination with a review of the literature, reveal a potential role for the VNTR variant of DRD4 in the development of depression in AD patients. The findings presented here need to be replicated in large, well characterised longitudinal cohorts. Copyright © 2009 John Wiley & Sons, Ltd.
Functionally linked resting‐state networks reflect the underlying structural connectivity architecture of the human brain
Authors: van den Heuvel Martijn P. , Mandl René C.W. , Kahn René S. , Hulshoff Pol Hilleke E. 
Published: February 2009

AbstractDuring rest, multiple cortical brain regions are functionally linked forming resting‐state networks. This high level of functional connectivity within resting‐state networks suggests the existence of direct neuroanatomical connections between these functionally linked brain regions to facilitate the ongoing interregional neuronal communication. White matter tracts are the structural highways of our brain, enabling information to travel quickly from one brain region to another region. In this study, we examined both the functional and structural connections of the human brain in a group of 26 healthy subjects, combining 3 Tesla resting‐state functional magnetic resonance imaging time‐series with diffusion tensor imaging scans. Nine consistently found functionally linked resting‐state networks were retrieved from the resting‐state data. The diffusion tensor imaging scans were used to reconstruct the white matter pathways between the functionally linked brain areas of these resting‐state networks. Our results show that well‐known anatomical white matter tracts interconnect at least eight of the nine commonly found resting‐state networks, including the default mode network, the core network, primary motor and visual network, and two lateralized parietal‐frontal networks. Our results suggest that the functionally linked resting‐state networks reflect the underlying structural connectivity architecture of the human brain. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.
Empathic neural responses to others' pain are modulated by emotional contexts
Authors: Han Shihui , Fan Yan , Xu Xiaojing , Qin Jungang , Wu Bing , Wang Xiaoying , Aglioti Salvatore M. , Mao Lihua 
Published: February 2009

AbstractRecent brain imaging studies indicate that empathy for pain relies upon both the affective and/or the sensorimotor nodes of the pain matrix, and empathic neural responses are modulated by stimulus reality, personal experience, and affective link with others. The current work investigated whether and how empathic neural responses are modulated by emotional contexts in which painful stimulations are perceived. Using functional magnetic resonance imaging (fMRI), we first showed that perceiving a painful stimulation (needle penetration) applied to a face with neutral expression induced activation in the anterior cingulate cortex (ACC) relative to nonpainful stimulation (Q‐tip touch). However, when observation of the painful stimuli delivered to a neutral face was intermixed with observation of painful or happy faces, the ACC activity decreased while the activity in the face area of the secondary somatosensory cortex increased to the painful stimulation. Moreover, the secondary somatosensory activity associated with the painful stimulation decreased when the painful stimulation was applied to faces with happy and painful expressions. The findings suggest that observing painful stimuli in an emotional context weakens affective responses but increases sensory responses to perceived pain and implies possible interactions between the affective and sensory components of the pain matrix during empathy for pain. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.
Source connectivity analysis with MEG and EEG
Authors: Schoffelen Jan‐Mathijs , Gross Joachim 
Published: February 2009

AbstractInteractions between functionally specialized brain regions are crucial for normal brain function. Magnetoencephalography (MEG) and electroencephalography (EEG) are techniques suited to capture these interactions, because they provide whole head measurements of brain activity in the millisecond range. More than one sensor picks up the activity of an underlying source. This field spread severely limits the utility of connectivity measures computed directly between sensor recordings. Consequentially, neuronal interactions should be studied on the level of the reconstructed sources. This article reviews several methods that have been applied to investigate interactions between brain regions in source space. We will mainly focus on the different measures used to quantify connectivity, and on the different strategies adopted to identify regions of interest. Despite various successful accounts of MEG and EEG source connectivity, caution with respect to the interpretation of the results is still warranted. This is due to the fact that effects of field spread can never be completely abolished in source space. However, in this very exciting and developing field of research this cautionary note should not discourage researchers from further investigation into the connectivity between neuronal sources. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.