bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of transient methods to probe the kinetics of the fischer‐tropsch synthesis on ruthenium part i: Methane transient
Authors: Mcgenity P. M. , Shang S. B. , Kenney C. N. , Patterson B. W. 
Published: January 2009

AbstractThe kinetics of methane formation during the Fischer‐Tropsch Synthesis (FTS) were investigated both experimentally and theoretically. The catalysts employed were ruthenium supported on oxide supports, i.e. Al2O3, SiO2, MgO, ZrO2 and TiO2. The experimental technique consisted of step changes between feed compositions. Four mechanistically based models were used to fit the transient experimental data. The results show that models based on direct dissociation of carbon monoxide perform better than those based on dissociation of carbon monoxide via a hydrogenated intermediate CHxO. It is concluded that the application of simplified elementary step modelling to transient responses in the Fischer‐Tropsch reaction provides a valuable tool in probing the kinetics of methane formation.
A new method for predicting thermal conductivity of pure organic liquids and their mixtures
Authors: Arikol Mahir , Gürbüz Hilal 
Published: January 2009

AbstractA new method based on Enskog's hard sphere theory for dense fluids and the principle of corresponding states is presented for predicting thermal conductivity of pure organic liquids and their mixtures. The thermal conductivities of alkanes, isoalkanes, aromatics, aldehydes, esters and ketones were calculated using this method which requires only critical properties and normal boiling point as input data. The predictions were compared with experimental data and other prediction methods over a wide range of temperatures (0.3 < Tr < 0.8) and highly satisfactory results were obtained. The method was also extended to mixtures employing simple mixing rules for calculating mixture properties.
Thermal stability of chloroform in the steam‐condensate cycle of CANDU‐PHW nuclear power plant
Authors: Lépine Louis , Gilbert Roland , Ouellet Lorenzo 
Published: January 2009

AbstractAnalysis of samples taken at the Gentilly 2 (Québec) CANDU‐PHW (CANadian Deuterium Uranium ‐ Pressurized Heavy Water) plant after chlorination and demineralization revealed the presence of all four trihalomethanes (THMs) (CHCl3, CHBrCl2, CHBr2Cl and CHBr3) and other unidentified halogenated volatile compounds. Among the THMs, chloroform was the major contaminant. A study of its thermal stability in water at different temperatures confirmed the degradation of the CHCl3 molecule according to the equation CHCl3 + H2O → CO + 3 HCl. The reaction follow a first order kinetics and has an activation energy of 100 kJ/mol. The estimated half‐life is six seconds at 260°C, the maximum temperature of the steam‐condensate cycle.
Effect of calcium chloride on vapor‐liquid equilibria of alcohol‐alcohol and alcohol‐water binary systems
Authors: Kumagae Yoshio , Mishima Kenji , Hongo Masaru , Kusunoki Mitsuhisa , Arai Yasuhiko 
Published: January 2009

AbstractThe vapor‐liquid equilibria of three alcohol‐alcohol binary mixtures (methanol‐ethanol, methanol‐1‐propanol and ethanol‐1‐propanol) and three alcohol‐water binary mixtures (methanol‐water, ethanol‐water and allyl alcohol‐water) containing calcium chloride were measured at 298.15 K using a flow‐type apparatus. The measured data of each ternary system were correlated by the use of a semi‐empirical model proposed by Hála. It was found that the model with the optimal value of the exponent β = 5.0 in the electrostatic interaction term, originally given as 3/2 by Hála, gives reasonable prediction to all the systems in this study.
Performance assessment measures for univariate feedback control
Authors: Desborough Lane , Harris Thomas 
Published: January 2009

AbstractA normalized performance index, η(b), is introduced to characterize the performance of feedback control schemes. η(b) is attractive because it provides a measure of the proximity of control to minimum variance control, which is the optimal feedback control provided that the process can be described by a linear transfer function with additive disturbance. Both time domain and spectral interpretations of this performance index are discussed. A fast, simple, on‐line method for estimating η(b) is given, along with some of the statistical properties of the estimator. Simulation and industrial examples demonstrate the utility of η(b/)
3‐D comparative behaviour of discrete transfer and imaginary planes methods for furnace modelling
Authors: Charette A. , Haidekker A. , Kocaefe Y. S. 
Published: January 2009

AbstractThe discrete transfer and imaginary planes methods are compared for accuracy and computation time in cartesian and cylindrical enclosures filled with grey gas. The reference solutions are given by the classical zone method. Comparisons are done for surface heat fluxes and gas radiative sources. A wide range of surface emissivities and gas absorption coefficients is analysed. In general, the discrete transfer method reveals superior for accuracy but consumes more computation time. The imaginary planes method loses accuracy when a high number of spatial divisions is used, however it is easy to apply.
Neural network based adaptive control via temporal pattern recognition
Authors: Megan Lawrence , Cooper Douglas J. 
Published: January 2009

AbstractThis paper presents a neural network approach to adaptive control through pattern recognition techniques. Two interconnected backpropagation networks are trained to translate error patterns resulting from sustained set point changes into predictions of mismatch between current internal model parameters, model gain and model time constant, and those which restore desired performance. The network predictions are then used to update a model based PI controller. The strategy is demonstrated on two simulations and a pilot scale process which are undergoing severe changes in model gain and time constant. The strategy compares favorably against a more traditional rule based pattern recognition approach.
Slow immiscible displacement flow in disordered porous media
Authors: Kiriakidis D.G. , Neale G.H. , Mitsoulis E. 
Published: January 2009

AbstractThe immiscible displacement of a wetting fluid by a non‐wetting fluid in a disordered porous medium is studied in the capillary region, i.e. when capillary forces are dominant, by using the invasion percolation model to describe the displacement mechanism. The porous medium is represented by a two‐dimensional network of interconnected capillaries whose radii follow a uniform size distribution. Disorder is assigned to the medium by considering the probabilities of occurrence of inaccessible pores, ps, and non‐conductive capillaries, pb. It is found that the dynamic behaviour of the displacing fluid and the fraction of invaded pores depend on the degree of disorder of the medium. The results can provide an interpretation of the effects of the dead‐end pore volume on the oil recovery and the displacement behaviour.
Synthesis, Chiral Resolution and Pharmacological Evaluation of a 2,3‐Benzodiazepine‐Derived Noncompetitive AMPA Receptor Antagonist
Authors: Calabrò Maria Luisa , Raneri Daniela , Ficarra Paola , Mennini Tiziana , Colleoni Simona , Grazioso Giovanni , Micale Nicola , Zappalà Maria , Grasso Silvana 
Published: January 2009

Abstract2,3‐Benzodiazepine derivatives: 1‐(4‐Aminophenyl)‐3,5‐dihydro‐3‐N‐ethylcarbamoyl‐5‐methyl‐7,8‐methylenedioxy‐4H‐2,3‐benzodiazepin‐4‐one was synthesized, and its enantiomers were separated by chiral HPLC. Pharmacological evaluation of each enantiomer showed that (S)‐(−)‐5 appears to be more potent than its optical antipode (R)‐(+)‐5 in an AMPA receptor binding assay.magnified imageThe resolution of 1‐(4‐aminophenyl)‐3,5‐dihydro‐3‐N‐ethylcarbamoyl‐5‐methyl‐7,8‐methylenedioxy‐4H‐2,3‐benzodiazepin‐4‐one (R,S)‐(±)‐5 by chiral HPLC and assignment of the absolute configuration of the two enantiomers was carried out. Compound (R,S)‐(±)‐5 and its enantiomers were tested in a binding assay to evaluate their affinity for AMPA receptors. Enantiomer (S)‐(−)‐5 appears to be more potent than its optical antipode (R)‐(+)‐5. In a primary culture of rat cerebellar granule cells, which express AMPA receptors, (R,S)‐(±)‐5 and (S)‐(−)‐5 inhibited kainate‐ induced [Ca2+]i increase, thus confirming the antagonism at the AMPA receptor.
Rapid measurements of diffusion using PFG: Developments and applications of the Difftrain pulse sequence
Authors: Mitchell Jonathan , Johns Michael L. 
Published: January 2009

AbstractPulsed‐field gradient (PFG) nuclear magnetic resonance (NMR) is one of the few experimental techniques that can determine directly mean square molecular displacements, allowing self‐diffusion coefficient of liquids to be derived. PFG measurements are used commonly for diffusion, flow, and microstructure characterization. However, these conventional PFG experiments are often time consuming, requiring the gradient strength or observation time to be incremented independently. Here we discuss how the rapid Difftrain pulse sequence has proved invaluable in the study of time sensitive systems by allowing multiple observation times to be probed in a single scan. Difftrain has been applied successfully to the study of emulsions, surfactant solutions, bead packs, and permeable rock cores. We discuss various implementations of the Difftrain pulse sequence, suggest suitable phase cycles, and review the applications to date. © 2009 Wiley Periodicals, Inc. Concepts Magn Reson Part A 34A: 1–15, 2009.
Compact magnets for magnetic resonance
Authors: Demas Vasiliki , Prado Pablo J. 
Published: January 2009

AbstractThis article provides an introduction to magnetic material properties and an overview of compact permanent magnet designs. The descriptions are focused on portable magnetic resonance instruments, including in‐magnet and open configurations. A few examples are presented for spectroscopy as well as for space‐resolved and relaxation measurements. © 2009 Wiley Periodicals, Inc. Concepts Magn Reson Part A 34A: 48–59, 2009.
The Molecular Cat
Authors: Pedio Maddalena , Chergui Majed 
Published: January 2009

AbstractA manifestation of electronic entanglement in core‐level spectroscopic measurements of diatomic molecules, reported recently by Schöffler and co‐workers, is discussed. The results are reminiscent of Schrödinger′s famous Gedanken experiment with the cat (see picture).magnified image
A Versatile Bisporphyrinoid Motif for Supramolecular Chirogenesis (Eur. J. Org. Chem. 2/2009)
Authors: Borovkov Victor , Inoue Yoshihisa 
Published: January 2009

AbstractThe cover picture shows a phenomenon of supramolecular chirogenesis in an achiral bisporphyrinoid host upon noncovalent interaction with chiral antipodal guests. This host–guest interaction results in the phenomenon of chirality transfer followed by the induction of circular dichroism in the porphyrin electronic transitions. Details are presented in the Microreview by V. Borovkov and Y. Inoue on p. 189 ff.
Amperometric Detection of Hydrogen Peroxide Using Glassy Carbon Electrodes Modified with Chromium Hexacyanoferrate/Single‐Walled Carbon Nanotube Nanocomposites
Authors: Zhang Wei , Wang Guangfeng , Zhang Xiaojun , Fang Bin 
Published: January 2009

AbstractChemical functionalization of single‐walled carbon nanotubes (SWNTs) has constructed plenty of new structures with useful properties. But the modification was often confined to organic molecules, either by covalence or noncovalence. In this report, SWNTs were successfully functionalized with one kind of electroactive inorganic compounds: chromium hexacyanoferrate (Cr hcf). The resulting Cr hcf/SWNTs nanocomposites were confirmed by Field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), UV‐vis absorption spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Cr hcf crystallites are observed to be finely attached to the SWNTs. The electrochemical properties of Cr hcf/SWNTs nanocomposites were also investigated. The nanocomposites modified glassy carbon (GC) electrode shows high electrocatalytic activity towards the reduction of H2O2 and the amperometric responses show a linear dependence on the concentration of H2O2 in a range of 0.5 μM to 10 mM (R=0.9989). In addition, the sensor has good stability and reproducibility.
Electrochemical Properties of Ordered Mesoporous Carbon Film Adsorbed onto a Self‐Assembled Alkanethiol Monolayer on Gold Electrode
Authors: Zheng Dan , Ye Jianshan , Zhou Liang , Zhang Yang , Yu Chengzhong 
Published: January 2009

AbstractA stable ordered mesoporous carbon (OMC) film electrode was successfully constructed by adsorbing OMC onto a self‐assembled monolayer (SAM) of C18H37SH chemisorbed on the Au electrode. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and electrochemical methods were used to characterize the properties of the OMC film electrode. The adsorbed OMC can restore the heterogeneous electron transfer almost totally blocked by the alkanethiol monolayer. Nyquist plots show a sharply decrease of the charge transfer resistance (Rct) of the Fe(CN)$\rm{ {_{6}^{3-/4-}}}$ couple at the OMC film electrode. Furthermore, the OMC film electrode is found to possess a significantly reduced interfacial capacitance and largely enhanced current response of hydrogen peroxide. This novel approach to the fabrication of stable OMC film electrode with excellent electrochemical properties is believed to be very attractive for electrochemical studies and electroanalytical applications.
Direct Electrochemistry of Hemoglobin Immobilized on Colloidal Gold‐Hydroxyapatite Nanocomposite for Electrocatalytic Detection of Hydrogen Peroxide
Authors: You Juan , Ding Weiping , Ding Shijia , Ju Huangxian 
Published: January 2009

AbstractA novel nanocomposite of colloidal gold (GNPs) and hydroxyapatite nanotubes (Hap) was prepared for immobilization of a redox protein, hemoglobin (Hb), on glassy carbon electrode. The immobilized Hb showed fast direct electron transfer and excellent electrocatalytic behavior toward reduction of hydrogen peroxide. A synergic effect between GNPs and Hap for accelerating the surface electron transfer of Hb was observed, which led to a pair of redox peaks with a formal potential of (−340±2) mV at pH 7.0, and a new biosensor for hydrogen peroxide with a linear range from 0.5 to 25 μM and a limit of detection of 0.2 μM at 3σ. Owing to the good biocompatibility of the nanocomposite, the biosensor exhibited good stability and acceptable reproducibility. The as‐prepared nanocomposite film provided a good matrix for protein immobilization and biosensor preparation.
New Electrocatalytic Reactions at a Mercury Electrode in the Presence of Homocysteine or Cysteine and Cobalt or Nickel Ions
Authors: Galík Michal , Bănică Florinel‐Gabriel , Bănică Ana , Švancara Ivan , Vytřas Karel 
Published: January 2009

AbstractHomocysteine (Hcy) and cysteine (Cys) mercury thiolate layers were prepared by anodic polarization of a mercury electrode in amino acid containing solutions and then investigated in the cathodic regime in the presence of Ni2+ or Co2+ ions. The sulfhydryl function in the mercury thiolate undergoes a slow disintegration resulting in surface‐attached mercury sulfide. During the cathodic scan, Hg2+ substitution by Ni2+ or Co2+ yields minute amounts of the relevant metal sulfide. Such a species catalyzes hydrogen evolution at −1.3 V vs. Ag|AgCl|KCl(3 M). Hcy experiences a faster decomposition and, consequently, displays a stronger catalytic effect. Each compound catalyzes the reduction of Ni2+ or Co2+, but only Cys (bound in metal complexes) induces typical catalytic hydrogen evolution processes such as the Brdička reaction (with Co2+; pH around 9), or the catalytic hydrogen prewave (CHP) (with Ni2+; pH near 7). On the other hand, Hcy catalyzes the hydrogen evolution in the presence of Co2+ at −1.5 V in the same way than sulfur derivatives with no amine function do. Metal sulfide formation does not interfere with CHP and Brdička processes. Correlations between the physical state of the metal sulfide (adsorbed molecule or aggregate form) and its catalytic properties are discussed and possible analytical applications suggested.
Toughening study of fire‐retardant high‐impact polystyrene
Authors: Wenguang Cui , Yanlei Gao , Fen Guo 
Published: January 2009

AbstractFire‐retardant high‐impact polystyrene (HIPS) was modified by melt blending with varying amounts of three types of tougheners. The effects of the tougheners on the properties of the fire‐retardant HIPS were studied by mechanical, combustion tests, and thermogravimetric analysis. The morphologies of fracture surfaces and char layers were characterized through scanning electron microscopy. The results show that the impact properties of styrene–butadiene–styrene (SBS)‐containing composites were better than those of ethylene–propylene–diene monomer (EPDM)‐containing or ethylene–vinyl acetate copolymer (EVA)‐containing composites. The tensile strength and flexural modulus of the fire‐retardant HIPS decreased evidently with the addition of tougheners. It is found that the compatibility between SBS copolymer and HIPS matrix was best among the three types of tougheners. The addition of SBS had little influence on the thermal property, residue, flammability, and morphology of char layer of the fire‐retardant HIPS, but the addition of EPDM rubber or EVA brought adverse influence on the residue, flammability, and morphology of char layer of the fire‐retardant HIPS, especially for EPDM. Copyright © 2009 John Wiley & Sons, Ltd.
Meshless Galerkin analysis of Stokes slip flow with boundary integral equations
Authors: Li Xiaolin , Zhu Jialin 
Published: January 2009

AbstractThis paper presents a novel meshless Galerkin scheme for modeling incompressible slip Stokes flows in 2D. The boundary value problem is reformulated as boundary integral equations of the first kind which is then converted into an equivalent variational problem with constraint. We introduce a Lagrangian multiplier to incorporate the constraint and apply the moving least‐squares approximations to generate trial and test functions. In this boundary‐type meshless method, boundary conditions can be implemented exactly and system matrices are symmetric. Unlike the domain‐type method, this Galerkin scheme requires only a nodal structure on the bounding surface of a body for approximation of boundary unknowns. The convergence and abstract error estimates of this new approach are given. Numerical examples are also presented to show the efficiency of the method. Copyright © 2009 John Wiley & Sons, Ltd.
Correlates of reward‐predictive value in learning‐related hippocampal neural activity
Authors: Okatan Murat 
Published: January 2009

AbstractTemporal difference learning (TD) is a popular algorithm in machine learning. Two learning signals that are derived from this algorithm, the predictive value and the prediction error, have been shown to explain changes in neural activity and behavior during learning across species. Here, the predictive value signal is used to explain the time course of learning‐related changes in the activity of hippocampal neurons in monkeys performing an associative learning task. The TD algorithm serves as the centerpiece of a joint probability model for the learning‐related neural activity and the behavioral responses recorded during the task. The neural component of the model consists of spiking neurons that compete and learn the reward‐predictive value of task‐relevant input signals. The predictive‐value signaled by these neurons influences the behavioral response generated by a stochastic decision stage, which constitutes the behavioral component of the model. It is shown that the time course of the changes in neural activity and behavioral performance generated by the model exhibits key features of the experimental data. The results suggest that information about correct associations may be expressed in the hippocampus before it is detected in the behavior of a subject. In this way, the hippocampus may be among the earliest brain areas to express learning and drive the behavioral changes associated with learning. Correlates of reward‐predictive value may be expressed in the hippocampus through rate remapping within spatial memory representations, they may represent reward‐related aspects of a declarative or explicit relational memory representation of task contingencies, or they may correspond to reward‐related components of episodic memory representations. These potential functions are discussed in connection with hippocampal cell assembly sequences and their reverse reactivation during the awake state. The results provide further support for the proposal that neural processes underlying learning may be implementing a temporal difference‐like algorithm. © 2009 Wiley‐Liss, Inc.
Does the cingulate cortex contribute to spatial conditional associative learning in the rat?
Authors: St‐Laurent Marie , Petrides Michael , Sziklas Viviane 
Published: January 2009

AbstractRats with lesions to the anterior or posterior (retrosplenial) region of the cingulate cortex and rats with lesions that included both the anterior and posterior cingulate cortex were tested on a visual–spatial conditional task in which they had to learn to approach one of the two objects depending on the spatial context within which they were embedded. Lesions restricted to either the anterior or the retrosplenial cingulate region did not impair learning of this task which is known to be very sensitive to the effects of hippocampal lesions. Complete lesions of the cingulate cortex gave rise to only a minor retardation in learning. In contrast, lesions to the retrosplenial cortex impaired performance on a spatial navigation task and the classic radial maze. These results suggest that the retrosplenial portion of the cingulate region forms part of a hippocampal circuit underlying learning about spatial responses. The dissociation between the effects of lesions of the cingulate region on different classes of behavior known to be associated with hippocampal function suggests that, although this neural structure does play a role in an extended hippocampal circuit underlying spatial learning, its role in such learning may be a selective one. © 2009 Wiley‐Liss, Inc.
Age‐dependent enhancement of inhibitory synaptic transmission in CA1 pyramidal neurons via GluR5 kainate receptors
Authors: Xu Changqing , Cui Changhai , Alkon Daniel L. 
Published: January 2009

AbstractChanges in hippocampal synaptic networks during aging may contribute to age‐dependent compromise of cognitive functions such as learning and memory. Previous studies have demonstrated that GABAergic synaptic transmission exhibits age‐dependent changes. To better understand such age‐dependent changes of GABAergic synaptic inhibition, we performed whole‐cell recordings from pyramidal cells in the CA1 area of acute hippocampal slices on aged (24–26 months old) and young (2–4 months old) Brown‐Norway rats. We found that the frequency and amplitude of spontaneous inhibitory postsynaptic current (IPSCs) were significantly increased in aged rats, but the frequency and amplitude of mIPSCs were decreased. Furthermore, the regulation of GABAergic synaptic transmission by GluR5 containing kainate receptors was enhanced in aged rats, which was revealed by using LY382884 (a GluR5 kainate receptor antagonist) and ATPA (a GluR5 kainate receptor agonist). Moreover, we demonstrated that vesicular glutamate transporters are involved in the kainate receptor dependent regulation of sIPSCs. Taken together, these results suggest that GABAergic synaptic transmission is potentiated in aged rats, and GluR5 containing kainate receptors regulate the inhibitory synaptic transmission through endogenous glutamate. These alterations of GABAergic input with aging could contribute to age‐dependent cognitive decline. © 2009 Wiley‐Liss, Inc.