bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Science Contribution to the BEN Control on Si(100) and 3C‐SiC(100): Towards Ultrathin Nanocrystalline Diamond Films
Authors: Arnault Jean‐Charles , Saada Samuel , Delclos Sophie , Rocha Licinio , Intiso Luciana , Polini Riccardo , Hoffman Alon , Michaelson Shaul , Bergonzo Philippe 
Published: August 2008

AbstractDeposition of thin and smooth nanocrystalline diamond films requires a high degree of control of the nucleation stage. The nature of the interface between diamond film and substrate is also important for some applications. The successive steps of the bias‐enhanced nucleation (BEN) process are studied in‐situ on Si(100) and 3C‐SiC(100) using electron spectroscopies. Thin nanodiamond films (80–900 nm) have been achieved on Si(100). The formation of a thin covering SiC layer (2–3 nm) during the plasma exposure for parameters stabilization (PEPS) step leads us to study the plasma/surface interactions on 3C‐SiC(100) surfaces. The C‐terminated 3C‐SiC(100) demonstrates a large inertia under microwave plasma (MP)CVD conditions. An enhancement of diamond nucleation on this surface is observed. Moreover, surface analysis reveals very little damage after BEN on 3C‐SiC surfaces.
A Theoretical Study of Nitrogen‐Induced Effects on Initial Steps of Diamond CVD Growth
Authors: Van Regemorter Tanguy , Larsson Karin 
Published: August 2008

AbstractAn investigation based on an ultra‐soft, pseudo‐potential, density functional theory (DFT) method, using a generalized gradient approximation (GGA) under periodic boundary conditions, is performed in order to investigate the effect of substitutional nitrogen on the CH3 adsorption and the H abstraction from the adsorbed CH3 species. Both (111) and (100)‐2x1 surface are considered with 4 and 6 substitutional N positions, respectively. For the two surface orientations, no strong effect of N is generally observed when positioning it within the first C layer (i.e., surface layer). The only exception is for N in one of three investigated first layer positions within the (100) surface, for which a spontaneous β‐scission occurs as a result of the H abstraction reaction. For N in the second carbon layer, the CH3 adsorption reaction is calculated to be strongly disfavored, whilst the H abstraction reaction is markedly improved.
Modelling the Influence of the Nucleation Density on Ultra Nano Crystalline Diamond Growth Morphology: Preliminary Results
Authors: Sternschulte Hadwig , Rabl Helga E. , Steinmüller‐Nethl Doris , Tilg Bernhard 
Published: August 2008

AbstractThe morphology of ultra nanocrystalline diamond (UNCD) films is modeled by a pure geometrical approach. Diamond spheres with a fixed radius are added randomly spread on a smooth substrate surface covered with diamond seeds in varied primary nucleation density. The secondary nucleation rate and the nucleation density on the bare substrate define the distribution of diamond spheres during each cycle. In preliminary results, this simple geometrical model leads to good comparison with published experimental data; low primary nucleation densities yield to the growth of separated diamond islands with a rough surface, the smoothest films are obtained with the highest primary nucleation densities.
First Total Synthesis of the Potent Anticancer Natural Product Dideoxypetrosynol A: Preparation of the “Skipped” (Z)‐Enediyne Moiety by Oxidative Coupling of Homopropargylphosphonium Ylide
Authors: Gung Benjamin W. , Omollo Ann O. 
Published: August 2008

AbstractDideoxypetrosynol A is a C30 polyacetylenic alcohol with C2 symmetry. The first total synthesis of both enantiomers of the potent anti‐cancer natural product (+)‐ and (–)‐dideoxypetrosynol A is reported. The key step is an oxidative coupling of a homopropargylphosphonium ylide to prepare the “skipped” (Z)‐enediyne moiety. The natural dideoxypetrosynol A was isolated as a racemic mixture as shown in structure 1. The absolute configurations of the chiral centers are established for the (+)‐ and (–)‐enantiomers using Burgess' enzymatic resolution procedure with Pseudomonas AK lipase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Simultaneous determination of nandrolone, testosterone, and methyltestosterone by multi‐immunoaffinity column and capillary electrophoresis
Authors: Qi Xiao‐Hua , Zhang Li‐Wei , Zhang Xin‐Xiang 
Published: August 2008

AbstractA multitarget antibody immunoaffinity column was proposed for the purification and enrichment of nandrolone, testosterone, and methyltestosterone from urine. Nandrolone‐3‐site substituted antigen was designed and synthesized and the polyclonal antibody was prepared with immunizing rabbits. The stationary phase of the immunoaffinity column was synthesized by covalently bonding the antibodies specific to nandrolone, testosterone, and methyltestosterone onto CNBr‐actived Sepharose 4B. The analytes of interest were extracted with a methanol/water mixture in one step. The immunoaffinity column showed high affinity and high selectivity to a class of structurally related compounds. The elution was then transferred to a micellar electrokinetic CE system with a running buffer of sodium borate and sodium cholate for separation and determination. Recoveries of the three steroids from complex matrix were 88–94% with RSD values less than 5.2%. Optimization of the immunoaffinity column purification was achieved and the feasibility of the technique for the analysis of steroid hormone was discussed. The results indicated that the combination of multi‐immunoaffinity column and CE was an effective technique, which was rapid, simple, and sensitive for the assay of steroids.
Bilayer disk capillary electrophoresis: A novel method to study drug partitioning into membranes
Authors: Boija Elisabet , Lundquist Anna , Nilsson Mikael , Edwards Katarina , Isaksson Roland , Johansson Gunnar 
Published: August 2008

AbstractCE in the presence of lipid bilayer disks was introduced as a new approach in membrane partitioning studies. The disks were used as a pseudostationary phase in the partial‐filling mode of CE and the partitioning of cationic drugs was determined. The migration times of the analytes increased linearly with the lipid amount in the system. An appropriate algorithm for the calculation of a partition coefficient is presented. In the disk‐shaped bilayers, which have excellent stability and shelf life, all of the lipids are readily available for interaction and the disks can be used as realistic cell membrane models.
Use of chemometric methodology in optimizing conditions for competitive binding partial filling affinity capillary electrophoresis
Authors: Montes Ruth E. , Hanrahan Grady , Gomez Frank A. 
Published: August 2008

AbstractThis work expands the knowledge of the use of chemometric response surface methodology (RSM) in optimizing conditions for competitive binding partial filling ACE (PFACE). Specifically, RSM in the form of a Box–Behnken design was implemented in flow‐through PFACE (FTPFACE) to effectively predict the significance of injection time, voltage, and neutral ligand (neutral arylsulfonamide) concentration, [Lo], on protein–neutral ligand binding. Statistical analysis results were used to create a model for response surface prediction via contour and surface plots at a given maximum response (ΔRMTR) to reach a targeted Kb = 2.50×106 M−1. The adequacy of the model was then validated by experimental runs at the optimal predicted solution (injection time = 2.3 min, voltage = 11.6 kV, [Lo] = 1.4 μM). The achieved results greatly extend the usefulness of chemometrics in ACE and provide a valuable statistical tool for the study of other receptor–ligand combinations.
Poly(methyl methacrylate) microchip affinity capillary gel electrophoresis of aptamer–protein complexes for the analysis of thrombin in plasma
Authors: Obubuafo Anne , Balamurugan Subramanian , Shadpour Hamed , Spivak David , McCarley Robin L. , Soper Steven A. 
Published: August 2008

AbstractThrombin generation in blood serves as an important marker for various hemostasis‐related diseases and conditions. Analytical techniques currently utilized for determining the thrombin potential of patients rely primarily on the enzymatic activity of thrombin. Microfluidic‐based ACE using fluorescently labeled aptamers as affinity probes could provide a simple and efficient technique for the real‐time analysis of thrombin levels in plasma. In this study, aptamers were used for the analysis of thrombin by affinity microchip CGE. The CGE used a poly(methyl methacrylate) (PMMA) microfluidic device for the sorting of the affinity complexes with a linear polyacrylamide (LPA) serving as the sieving matrix. Due to the fact that the assay was run under nonequilibrium electrophoresis conditions, the presence of the sieving gel was found to stabilize the affinity complex, providing improved electrophoretic performance compared to free‐solution electrophoresis. Two fluorescently labeled aptamer affinity probes, HD1 and HD22, which bind to exosites I and II, respectively, of thrombin were investigated. With an electric field strength of 300 V/cm, two well‐resolved peaks corresponding to free aptamer and the thrombin–aptamer complex were obtained in less than 1 min of separation time with a run‐to‐run and chip‐to‐chip reproducibility (RSD) of migration times <10% using both aptamers. HD22 affinity assays of thrombin produced baseline‐resolved peaks with favorable efficiency due to its higher binding affinity, whereas HD1 assays showed poorer resolution of the free aptamer and complex peaks. HD22 was used in determining the level of thrombin in human plasma. Assays were performed directly on plasma that was diluted to 10% v/v. Thrombin was successfully analyzed by microchip CGE at a concentration level of 543.5 nM for the human plasma sample.
Evaluation of on‐line solid phase extraction‐capillary electrophoresis‐electrospray‐mass spectrometry for the analysis of neuropeptides in human plasma
Authors: Hernández Elena , Benavente Fernando , Sanz‐Nebot Victoria , Barbosa José 
Published: August 2008

AbstractIn this study, the suitability of SPE coupled on‐line to CE‐electrospray‐MS (SPE‐CE‐ESI‐MS) was evaluated for the analysis of neuropeptides in human plasma. First, CE‐ESI‐MS was investigated and a sample pretreatment based on precipitation with ACN was used for cleanup of plasma samples. The main quality parameters were determined and were consistent with those previously obtained for the analysis of standard mixtures, e.g., the LODs were of around 1 μg/mL. SPE‐CE‐ESI‐MS employing microcartridges containing a C18 stationary phase was explored in order to decrease the LODs. A double‐step sample cleanup pretreatment consisting of precipitation with ACN and ultrafiltration through 3000 Da MW cut‐off membranes was needed to prevent the microcartridge saturation. Repeatability, reproducibility, linearity, and LODs of the SPE‐CE‐ESI‐MS method and the durability of the microcartridges were studied. The LODs were markedly improved, ranging between 10 and 0.1 ng/mL depending on the peptide.
Multiplexed detection and applications for separations on parallel microchips
Authors: Dishinger John F. , Kennedy Robert T. 
Published: August 2008

AbstractMuch work has been performed since the development of the lab‐on‐a‐chip concept that has brought microfabricated systems to the forefront of bioanalytical research. The success of using these microchips for performing complicated biological assays faster and cheaper than conventional methods has facilitated their emerging popularity among researchers. A recently exploited advantage of microfabricated technology has led to the creation of single wafers with multiple channel manifolds for high‐throughput experiments. Efforts toward parallel microchip development have yielded fascinating new devices for chemical separations showing the potential for replacing conventional multiplexing techniques. This review will focus on recent work toward multiplexed separations on microdevices and complementary detection instrumentation.
Behavior of interacting species in vacancy affinity capillary electrophoresis described by mass balance equation
Authors: Sun Ying , Fang Ning , Chen David D. Y. 
Published: August 2008

AbstractVacancy ACE (VACE) is one of the ACE methods, and has been used to study binding interactions between different biomolecules. Thermodynamic binding constants can be estimated with nonlinear regression methods. With a highly efficient computer simulation program (SimDCCE), it is possible to demonstrate the detailed behaviors of each species during the interaction process under different conditions. In this work, thirteen scenarios in four different combinations of migration orders of the free protein, free drug, and complex formed are studied. The detailed interaction process between protein and ligand is discussed and illustrated based on the mass balance equation, also called mass transfer equation. By properly setting the parameters in the simulation model, the influence of different factors during the interaction process can be well understood.
Clinically relevant advances in on‐chip affinity‐based electrophoresis and electrochromatography
Authors: Hou Chenlu , Herr Amy E. 
Published: August 2008

AbstractClinical and point‐of‐care disease diagnostics promise to play an important role in personalized medicine, new approaches to global health, and health monitoring. Emerging instrument platforms based on lab‐on‐a‐chip technology can confer perfomance advantages successfully exploited in electrophoresis and electrochromatography to affinity‐based electrokinetic separations. This review surveys lab‐on‐a‐chip diagnostic developments in affinity‐based electokinetic separations for quantitation of proteins, integration of preparatory functions needed for subsequent analysis of diverse biological samples, and initial forays into multiplexed analyses. The technologies detailed here underpin new clinical and point‐of‐care diagnostic strategies. The techniques and devices promise to advance translation of until now laborabory‐based sample preparation and analytical assays to near‐patient settings.
Micro‐structured Devices for Chemical Sensing of Flavor and Fragrance
Authors: Schimmelpfennig M. , Dornbusch K. , Bannert M. , Feller K.‐H. 
Published: August 2008

AbstractThe aim of this study was to design, develop and test an integrated micro‐analytical system. Of special interest are micro‐fluidic and micro‐sensor applications in the field of chemical analysis, such as the optical detection of parameter changes, optical recognition of component profiles and technological micro‐reaction applications. For this purpose, a modular system was developed, which enables the realization of various application cases in an uncomplicated manner, and to execute (via serial or parallel combination of components) usually not compatible tasks. Software components were developed to control the measuring procedure as well as to execute the data interpretation up to a chemometrical discriminant analysis. Application is directed to the production and product control in life sciences mainly for food, natural products, cosmetics and pharmaceutics.
Solar photocatalytic removal of metal ions from industrial wastewater
Authors: Kabra Kavita , Chaudhary Rubina , Sawhney R.L. 
Published: August 2008

AbstractThis article describes the photocatalytic reduction and deposition of four metal ions Cr(VI), Ni(II), Zn(II), and Cu(II) present in the wastewater from a chrome plating industry using solar energy irradiated TiO2. A parabolic trough reactor was used to carry out the reaction. Experiments were carried out to find an optimum dose of hole scavenger used (citric acid). The adsorption and reduction of the metal ions at different pH values was also investigated.It was observed that the solar photocatalytic process was effective in removing most of the metal ions in specific reaction conditions. Alkaline pH was found to be more suitable for removal of nickel and zinc. However, Cr(VI) reduced completely even at catalyst concentrations as low as 0.5 mg/L at pH 2. Maximum reaction was completed in the first 4 h of solar exposure. © 2008 American Institute of Chemical Engineers Environ Prog, 2008
Catalytic and photocatalytic degradation of ozone via utilization of controllable nano‐Ag modified on TiO2
Authors: Lin Yu‐chih , Lin Chia‐hsin 
Published: August 2008

AbstractTo resolve increasing ozone pollution, nano‐silver‐anchored titanium dioxide (nano‐Ag/TiO2), with a controllable diameter, synthesized by a photoreduction method, for ozone degradation is presented in this study.In the presence of ultraviolet (UV) irradiation, the nano‐Ag/TiO2 catalyst exhibited high efficiency for ozone degradation, at ∼98–99% for all experiments. However, the efficiency of pure TiO2 for ozone degradation rapidly dropped and became inefficient after 160 min. This is because ozone oxidized the surface of TiO2 and formed an oxidative layer on the TiO2 surface; then the photocatalytic ability of the re‐oxidized TiO2 for ozone degradation was greatly reduced. The results also indicated that ozone was effectively degraded via the nano‐Ag/TiO2 catalyst even without UV irradiation. The catalytic performance of nano‐Ag/TiO2 for ozone degradation was enhanced by reducing the diameters and by effectively dispersing the Ag nanoparticles. In addition, the photocatalytic ozone degradation via nano‐Ag/TiO2 revealed no decay at a relative humidity of 70% during the experimental period, and maintained excellent performance compared with that of pure TiO2. © 2008 American Institute of Chemical Engineers Environ Prog, 2008
Dynamics of cortical responses to tone pairs in relation to task difficulty: A MEG study
Authors: Nahum Mor , Renvall Hanna , Ahissar Merav 
Published: August 2008

AbstractWe investigated the effect of task difficulty on the dynamics of auditory cortical responses. Whole‐scalp magnetoencephalographic (MEG) signals were recorded while subjects performed a same/different frequency discrimination task on equiprobable tone pairs applied in blocks of five, which were separated by a 10 s intertrial interval. Task difficulty was manipulated by the interpair frequency difference. The manipulation of task difficulty affected the amplitude of the N100m response to the first tone and the latency of the N100m response to the second tone in each pair. The N100m responses were smaller and peaked significantly later in the difficult than in the easy condition. The later processing field (PF) responses were longer in duration in the difficult condition. In both conditions, the duration of the PF response was negatively correlated with the subject's performance in the task, and was longer in the less successful subjects. The PF response may thus reflect the subjects' effort to resolve the task. The N100m and the PF responses did not differ between the tone pairs along the five‐pair trial as a function of task difficulty, suggesting that changes in response along the five‐pair trial are not easily affected by high‐level manipulations. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Attentional load modifies early activity in human primary visual cortex
Authors: Rauss Karsten S. , Pourtois Gilles , Vuilleumier Patrik , Schwartz Sophie 
Published: August 2008

AbstractRecent theories of selective attention assume that the more attention is required by a task, the earlier are irrelevant stimuli filtered during perceptual processing. Previous functional MRI studies have demonstrated that primary visual cortex (V1) activation by peripheral distractors is reduced by higher task difficulty at fixation, but it remains unknown whether such changes affect initial processing in V1 or subsequent feedback. Here we manipulated attentional load at fixation while recording peripheral visual responses with high‐density EEG in 28 healthy volunteers, which allowed us to track the exact time course of attention‐related effects on V1. Our results show a modulation of the earliest component of the visual evoked potential (C1) as a function of attentional load. Additional topographic and source localization analyses corroborated this finding, with significant load‐related differences observed throughout the first 100 ms post‐stimulus. However, this effect was observed only when stimuli were presented in the upper visual field (VF), but not for symmetrical positions in the lower VF. Our findings demonstrate early filtering of irrelevant information under increased attentional demands, thus supporting models that assume a flexible mechanism of attentional selection, but reveal important functional asymmetries across the VF. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Audiovisual integration during speech comprehension: An fMRI study comparing ROI‐based and whole brain analyses
Authors: Szycik Gregor R. , Jansma Henk , Münte Thomas F. 
Published: August 2008

AbstractVisual information (lip movements) significantly contributes to speech comprehension raising the question for the neural implementation of audiovisual (AV) integration during speech processing. To replicate and extend earlier neuroimaging findings, we compared two different analysis approaches in a slow event‐related fMRI study of healthy native speakers of German who were exposed to AV speech stimuli (disyllabic nouns) with audio and visual signals being either congruent or incongruent. First, data was subjected to whole brain general linear model analysis after transformation of all individual data sets into standard space. Second, a region of interest (ROI) approach based on individual anatomy was used with ROI defined in areas identified previously as being important for AV processing. Standard space analysis revealed a widespread cortical network including the posterior part of the left superior temporal sulcus, Broca's region and its right hemispheric counterpart showing increased activity for incongruent stimuli. The ROI approach allowed to identify differences in activity between Brodmann areas 44 and 45, within Broca's area for incongruent stimulation, and also allowed to study activity of subdivisions of superior temporal regions. The complementary strengths and weaknesses of the two analysis approaches are discussed. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
Stability of tactile‐ and pain‐related fMRI brain activations: An examination of threshold‐dependent and threshold‐independent methods
Authors: Taylor Keri S. , Davis Karen D. 
Published: August 2008

AbstractFunctional MRI can be used to assess brain plasticity over time. To confidently attribute changes in activation patterns to cortical plasticity, it is important to establish the stability of cortical activation patterns. Because little is known concerning the stability of somatosensory‐evoked brain responses, we assessed the reproducibility of within‐subject responses in key somatosensory regions [thalamus, primary and secondary cortex (S1, S2)] to tactile and painful stimuli using threshold‐dependent and threshold‐independent analyses. Six subjects underwent four biweekly scanning sessions during which tactile and painful stimuli were applied to the hand. Standard thresholding and voxel counting techniques were compared with a novel threshold‐independent method utilizing percent signal change within the regions of interest. Contralateral S1 and S2 were qualitatively reproducible during tactile stimulation, with overlapping activations >85% of the time. S2 was also highly reproducible during painful stimulation (88%), whereas S1 was less reproducible (44%). However, activation in the thalamus to both tactile and painful stimulation was highly variable. Ipsilateral activation was consistent within S2 but sparse within S1 and thalamus. Deactivations within ipsilateral S1 occurred 48% of the time with tactile stimuli, and 90% of the time with painful stimuli. Within contralaterally activated regions intraclass correlations (ICCs) were very high using the unthresholded method regardless of the type of stimulation, whereas much lower ICCs arose from the thresholded analyses. These data indicate that a threshold‐independent analysis can produce more reproducible outcomes than a standard threshold‐dependent analysis. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.