bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation, Geometric and Electronic Structures of [Bi2Cu4(SPh)8(PPh3)4] with a Bi2 Dumbbell, [Bi4Ag3(SePh)6Cl3(PPh3)3]2 and [Bi4Ag3(SePh)6X3(PPhiPr2)3]2 (X = Cl, Br) with a Bi4 Unit
Authors: Sommer Heino , Eichhöfer Andreas , Drebov Nedko , Ahlrichs Reinhart , Fenske Dieter 
Published: October 2008

AbstractBiBr3 and CuCl react with S(Ph)SiMe3 in thf solution in the presence of PPh3 to yield [BiCu2(SPh)3Br2(PPh3)3] (1). The reaction of 1 with 2 equiv. of NaSPh gives rise to [Bi2Cu4(SPh)8(PPh3)4] (2) containing a Bi2 dumbbell. In this paper we further report the synthesis and characterization of the new cluster complexes [Bi4Ag3(SePh)6Cl3(PPh3)3]2 (3) and[Bi4Ag3(SePh)6X3(PPhiPr2)3]2 [X = Cl (4), Br (5)]. In the surprisingly formed species 3–5 a formal charged Bi46+ unit is observed. Compounds 3–5 were prepared by the reaction of BiX3 (X = Cl, Br), AgStBu, Se(Ph)SiMe3 and phosphane (PPh3, PPhiPr2). The structures of the compounds were determined by single‐crystal X‐ray analysis. Additionally, theoretical investigations were preformed to rationalize the bonding situation in 2–5. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Organometallic Diiron Complex Chemistry Related to the [2Fe]H Subsite of [FeFe]H2ase (Eur. J. Inorg. Chem. 30/2008)
Authors: Capon Jean‐François , Gloaguen Frédéric , Pétillon François Y. , Schollhammer Philippe , Talarmin Jean 
Published: October 2008

AbstractThe cover picture shows a schematic view of the diiron active site of [FeFe] hydrogenases that catalyze the reversible H+/H2 conversion. Attempts to have a better understanding of the activity of this natural system and to design new organometallic electrocatalysts for the production of H2 have allowed new insight into the chemistry of sulfur‐rich diiron carbonyls. Details are presented in the Microreview by P. Schollhammer et al. on p. 4671 ff.
Synthesis, Derivatisation and Structural Characterisation of a New Macrobicyclic Phosphane Oxide Cryptand
Authors: Däbritz Frank , Jäger Anne , Bauer Ingmar 
Published: October 2008

AbstractFollowing a tripod‐coupling strategy a new phosphane oxide cage compound was synthesised in comparatively high yield. The X‐ray crystal structure obtained shows a large cavity and an out‐positioned P=O moiety in the solid state. A stable in‐isomer was not detected, either during synthesis or by isomerisation. We attribute this fact to homeomorphic isomerisation in solution at room temperature.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Electrochemical Oxidation of Methionine Mediated by a Fullerene‐C60 Modified Gold Electrode
Authors: Tan W. T. , Goh J. K. 
Published: October 2008

AbstractThe usefulness of a C60‐fullerene modified gold (Au) electrode in mediating the oxidation of methionine in the presence of potassium ions electrolyte has been demonstrated. During cyclic voltammetry, an oxidation peak of methionine appearing at +1.0 V vs. Ag/AgCl was observed. The oxidation current of methionine is enhanced by about 2 times using a C60 modified gold electrode. The current enhancement is significantly dependent on pH, temperature and C60 dosage. Calibration plot reveals linearity of up to 0.1 mM with a current sensitivity of close to 50 mA L mol−1 and detection limit of 8.2×10−6 M. The variation of scan rate study shows that the system undergoes diffusion‐controlled process. Diffusion coefficient and rate constant of methionine were determined using hydrodynamic method (rotating disk electrode) with values of 1.11×10−5 cm2 s−1 and 0.0026 cm s−1 respectively for unmodified electrode while the values of diffusion coefficient and rate constant of methionine using C60 modified Au electrode are 5.7×10−6 cm2 s−1 and 0.0021 cm s−1 respectively.
Direct Electrochemistry and Electrocatalysis of Hemoglobin in Lipid Film Incorporated with Room‐Temperature Ionic Liquid
Authors: Li Gaiping , Du Liangwei , Chen Hongjun , Zhang Lixue , Wang Erkang 
Published: October 2008

AbstractA facile phospholipid/room‐temperature ionic liquid (RTIL) composite material based on dimyristoylphosphatidylcholine (DMPC) and 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim]PF6) was exploited as a new matrix for immobilizing protein. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were adopted to characterize this composite film. Hemoglobin (Hb) was chosen as a model protein to investigate the composite system. UV‐vis absorbance spectra showed that Hb still maintained its heme crevice integrity in this composite film. By virtue of the Hb/DMPC/[bmim]PF6 composite film‐modified glassy carbon electrode (GCE), a pair of well‐defined redox peaks of Hb was obtained through the direct electron transfer between protein and underlying GCE. Moreover, the reduction of O2 and H2O2 at the Hb/DMPC/[bmim]PF6 composite film‐modified GCE was dramatically enhanced.
Screen‐Printed Contactless Conductivity Detector for Microchip Capillary Electrophoresis
Authors: Wang Joseph , Chen Gang , Chatrathi Madhu Prakash , Wang Mei , Rinehart Robert , Muck Alexander 
Published: October 2008

AbstractA new method for mass fabrication of silver ink conductivity detector electrodes for poly(methylmethacrylate) (PMMA) microchip electrophoretic systems has been developed based on screen‐printing technology. Printing of silver conductivity electrodes was performed through a patterned stencil on thin PMMA sheets. Following the electrode fabrication, the PMMA sheets are cut into cover sheets, and are aligned and sealed to the channel plate thus establishing a complete microchip separation device. The effects of the electrode width and spacing on the response and resolution have been investigated and the optimized electrode performance was compared to commonly used aluminum electrodes in the determination of ammonium, methyl ammonium, and sodium. The utility of the screen‐printed contactless conductivity detector (SPCCD) electrodes is further demonstrated for the separation and detection of organic acids with excellent reproducibility (RSD values of 3.7% and 4.1% for oxalate and tartrate, respectively). The thick‐film fabrication of the electrode material demonstrates the ability to mass‐fabricate detection devices with total process of device fabrication requiring less than 4 h (including the fabrication of channel plate, cover sheet with the electrodes, and subsequent bonding). The fabrication method described here is convenient and does not compromise the detector performance, hence offers great promise for producing single use field deployable analytical microsystems.
Surface Characterization and the Gas Response of a Mixed, Fe2O3Fe2(MoO4)3, Oxide to Low Concentrations of H2S in Air
Authors: Kersen Ülo , Holappa Lauri 
Published: October 2008

AbstractThe preparation and H2S sensing potential of thick‐films of a mixed oxide, Fe2O3Fe2(MoO4)3, were investigated. A Fourier‐transform infrared (FTIR) study confirmed the existence of sulfur species at the surface after the interaction of H2S gas with the mixed oxide. The starting material, β‐FeMoO4, was synthesized by a solvothermal method, followed by supercritical drying. Heat treatment of this material (oxidation) above 500 °C resulted in the formation of Fe2O3Fe2(MoO4)3 mixed oxide, where Fe2O3 was a by‐product. An increase in the conductivity of the films in the presence of H2S gas (concentration range 1–20 ppm in air) was observed with the simultaneous formation of water and sulfide ions at 225 °C. An improvement of the H2S sensing potential is obtained, using an intermediate short heat treatment at higher temperature (500 °C) in the beginning of recovery (desorption) phase. This intermediate high temperature, used before every expected exposure to H2S gas, may contribute the formation of an initial surface coverage of O2−.
Electrochemical Properties of Different Carbon‐Fiber Microelectrodes Using Fast‐Scan Cyclic Voltammetry
Authors: Huffman Megan L. , Venton B. Jill 
Published: October 2008

AbstractIn this study, fast‐scan cyclic voltammetry (FSCV) was used to compare responses to neurochemicals of various carbon fibers, with different conductivities and carbon precursors. Pitch‐based P‐25 and P‐55 fibers were compared to polyacrylonitrile‐based T‐650 and HM fibers. Highly conductive fibers such as P‐55s or HMs have larger background charging currents than lower conductivity fibers. Using a standard waveform, PAN‐based fibers and less conductive fibers experience faster kinetics. With a more positive switching potential, higher conductivity fibers show faster kinetics for catecholamines and larger oxidation peak currents for anions such as ascorbic acid and 3,4‐dihydroxyphenylacetic acid (DOPAC). Conductivity was found to have the greatest impact on fiber performance, but the nature of its effect depends on the waveform used and the analyte detected.
Partial oxidation and oxidative polymerization of metallothionein
Authors: Haase Hajo , Maret Wolfgang 
Published: October 2008

AbstractOne mechanism for regulation of metal binding to metallothionein (MT) involves the non‐enzymatic or enzymatic oxidation of its thiols to disulfides. Formation and speciation of oxidized MT have not been investigated in detail despite the biological significance of this redox biochemistry. While metal ion‐bound thiols in MT are rather resistant towards oxidation, free thiols are readily oxidized. MT can be partially oxidized to a state in which some of its thiols remain reduced and bound to metal ions. Analysis of the oxidation products with SDS‐PAGE and a thiol‐specific labeling technique, employing eosin‐5‐iodoacetamide, demonstrates higher‐order aggregates of MT with intermolecular disulfide linkages. The polymerization follows either non‐enzymatic or enzymatic oxidation, indicating that it is a general property of oxidized MT. Supramolecular assemblies of MT add new perspectives to the complex redox and metal equilibria of this protein.
Optimal separation times for electrical field flow fractionation with Couette flows
Authors: Pascal Jennifer , O'Hara Ryan , Oyanader Mario , Arce Pedro E. 
Published: October 2008

AbstractThe prediction of optimal times of separation as a function of the applied electrical field and cation valence have been studied for the case of field flow fractionation [Martin M., Giddings J. C., J. Phys. Chem. 1981, 85, 727] with charged solutes. These predictions can be very useful to a priori design or identify optimal operating conditions for a Couette‐based device for field flow fractionation when the orthogonal field is an electrical field. Mathematically friendly relationships are obtained by applying the method of spatial averaging to the solute species continuity equation; this is accomplished after the role of the capillary geometrical dimensions on the applied electrical field equations has been assessed [Oyanader M. A., Arce P., Electrophoresis 2005; 26, 2857]. Moreover, explicit analytical expressions are derived for the effective parameters, i.e. diffusivity and convective velocity as functions of the applied (orthogonal) electrical field. These effective transport parameters are used to study the effect of the cation valence of the solutes and of the magnitude of the applied orthogonal electrical field on the values of the optimal time of separation. These parameters play a significant role in controlling the optimal separation time, leading to a family of minimum values, for particular magnitudes of the applied orthogonal electrical field.
Fluorophore‐assisted carbohydrate electrophoresis for the determination of molecular mass of heparins and low‐molecular‐weight (LMW) heparins
Authors: Buzzega Dania , Maccari Francesca , Volpi Nicola 
Published: October 2008

AbstractWe report the use of fluorophore‐assisted carbohydrate electrophoresis (FACE) to determine the molecular mass (M) values of heparins (Heps) and low‐molecular‐weight (LMW)‐Hep derivatives. Hep are labeled with 8‐aminonaphthalene‐1,3,6‐trisulfonic acid and FACE is able to resolve each fraction as a discrete band depending on their M. After densitometric acquisition, the migration distance of each Hep standard is acquired and the third‐grade polynomial calibration standard curve is determined by plotting the logarithms of the M values as a function of migration ratio. Purified Hep samples having different properties, pharmaceutical Heps and various LMW‐Heps were analyzed by both FACE and conventional high‐performance size‐exclusion liquid chromatography (HPSEC) methods. The molecular weight value on the top of the chromatographic peak (Mp), the number‐average Mn, weight‐average Mw and polydispersity (Mw/Mn) were examined by both techniques and found to be similar. This approach offers certain advantages over the HPSEC method. The derivatization process with 8‐aminonaphthalene‐1,3,6‐trisulfonic acid is complete after 4 h so that many samples may be analyzed in a day also considering that multiple samples can be run simultaneously and in parallel and that a single FACE analysis requires approx. 15 min. Furthermore, FACE is a very sensitive method as it requires approx. 5–10 μg of Heps, about 10–100‐fold lower than samples and standards used in HPSEC evaluation. Finally, the utilization of mini‐gels allows the use of very low amounts of reagents with neither expensive equipment nor any complicated procedures having to be applied. This study demonstrates that FACE analysis is a sensitive method for the determination of the M values of Heps and LMW‐Heps with possible utilization in virtually any kind of research and development such as quality control laboratories due to its rapid, parallel analysis of multiple samples by means of common and simple largely used analytical laboratory equipment.
Quantitative particle size, microtextural and outline shape analyses of glacigenic sediment reworked by paraglacial debris flows
Authors: Curry A. M. , Porter P. R. , Irvine‐Fynn T. D. L. , Rees G. , Sands T. B. , Puttick J. 
Published: October 2008

AbstractParticle size analysis and scanning electron microscopy have been used with some success to differentiate sediments sampled from varying geomorphological environments. In the paraglacial environment, however, discrimination of paraglacially reworked deposits from in situ glacigenic deposits has proven to be problematic. We consider till sediments that have been reworked by paraglacial debris flows and in situ, unreworked parent material, and apply a series of quantitative techniques in an attempt to discriminate samples from each environment. Initial analysis of particle size suggests some eluviation of fines from the debris‐flow‐reworked deposits but is of insufficient significance to allow reliable differentiation of geomorphological environment. Similarly, although slight differences are identified in terms of quartz grain surface microtextures and quartz grain outline shape, subsequent PCA, cluster and Fourier analyses fail to reliably differentiate quartz grains from each geomorphological environment, owing to high levels of intra‐sample heterogeneity. This lack of apparent difference may arise from a lack of paraglacial process operation of significant magnitude or duration for a characteristic process imprint to emerge at this scale of observation. Accordingly, further assessment of particle‐size and microtextural characteristics of glacial and paraglacial sediments may be most fruitful where sediments have been reworked over long distances. Moreover, differentiating glacial from paraglacial deposits is likely to yield the most reliable results where rigorous statistical analyses are combined with a wide range of sedimentological and geomorphological techniques. Copyright © 2008 John Wiley and Sons, Ltd.
Robust chronologies for landform development
Authors: Chiverrell R. C. , Foster G. C. , Thomas G. S. P. , Marshall P. , Hamilton D. 
Published: October 2008

AbstractObtaining chronological control for geomorphological sequences can be problematic due to the fragmentary and non‐sequential nature of sediment and landform archives. The robust analysis of 14C ages is often critical for the interpretation of these complicated sequences. This paper demonstrates a robust methodology for the 14C dating of geomorphological sequences using a case study from the lower Ribble valley, northwest England. The approach adopted incorporates using greater numbers of ages, targeting plant macrofossils, obtaining replicate measurements from single horizons to assess the extent of reworking and the use of Bayesian approaches to test models of the relative order of events. The extent of reworking of organic materials and space‐time dynamics of fluvial change means that it is critical that chronological control is sufficiently resourced with 14C measurements. As a result Bayesian approaches are increasingly important for the evaluation of large data sets. Assessing the conformability of relative order models informed by interpretation of the geomorphology can identify contexts or materials that are out of sequence, and focuses attention on problem materials (reworking) and errors in interpretation (outlier ages). These relative order models provide a framework for the interrogation of sequences and a means for securing probability‐based age estimates for events that occur between dated contexts. This approach has potential value in constraining the sequence of geomorphological development at scales that vary from individual sites to a catchment or region, furthering understanding of forcing and change in geomorphological systems. Copyright © 2008 John Wiley & Sons, Ltd.
On a dynamic mixture GARCH model
Authors: Cheng Xixin , Yu Philip L. H. , Li W. K. 
Published: October 2008

AbstractThis paper proposes a new mixture GARCH model with a dynamic mixture proportion. The mixture Gaussian distribution of the error can vary from time to time. The Bayesian Information Criterion and the EM algorithm are used to estimate the number of parameters as well as the model parameters and their standard errors. The new model is applied to the S&P500 Index and Hang Seng Index and compared with GARCH models with Gaussian error and Student'sterror. The result shows that the IGARCH effect in these index returns could be the result of the mixture of one stationary volatility component with another non‐stationary volatility component. The VaR based on the new model performs better than traditional GARCH‐based VaRs, especially in unstable stock markets. Copyright © 2008 John Wiley & Sons, Ltd.
Stock market volatility and the forecasting performance of stock index futures
Authors: Wang Janchung 
Published: October 2008

AbstractThis study attempts to apply the general equilibrium model of stock index futures with both stochastic market volatility and stochastic interest rates to the TAIFEX and the SGX Taiwan stock index futures data, and compares the predictive power of the cost of carry and the general equilibrium models. This study also represents the first attempt to investigate which of the five volatility estimators can enhance the forecasting performance of the general equilibrium model. Additionally, the impact of the up‐tick rule and other various explanatory factors on mispricing is also tested using a regression framework. Overall, the general equilibrium model outperforms the cost of carry model in forecasting prices of the TAIFEX and the SGX futures. This finding indicates that in the higher volatility of the Taiwan stock market incorporating stochastic market volatility into the pricing model helps in predicting the prices of these two futures. Furthermore, the comparison results of different volatility estimators support the conclusion that the power EWMA and the GARCH(1,1) estimators can enhance the forecasting performance of the general equilibrium model compared to the other estimators. Additionally, the relaxation of the up‐tick rule helps reduce the degree of mispricing. Copyright © 2008 John Wiley & Sons, Ltd.
Estimation of temperature distribution in biological tissue by using solutions of bioheat transfer equation
Authors: Maruyama Shigenao , Okajima Junnosuke , Komiya Atsuki , Takeda Hiroki 
Published: October 2008

AbstractA living body has a system for maintaining its temperature. We have investigated the heat transfer characteristics common to each organ and therapy using heat transfer. The one‐dimensional bioheat transfer equation with bioheat generation was converted into a dimensionless form and solved by Laplace transformation on the assumption that biological tissue is homogeneous. A dimensionless steady‐state solution and transient solution were derived analytically. These solutions can represent the characteristics of the temperature distribution common to each organ. Comparison with numerical solutions has confirmed that these solutions can be applied to estimate the temperature distribution of inhomogeneous biological tissue. It is proved that the size of the region where temperature change occurs, the steady‐state thermal penetration depth, is decided by biological properties. Furthermore, the time needed to reach a steady state, or the time it takes for biological tissue to reach a steady state, is calculated by using these solutions. Additionally, a temperature chart was proposed for each organ or tissue. This chart can serve as a guideline for medical doctors in formulating thermal therapy. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(6): 374– 386, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20210
Melting of a vertical ice cylinder inside a rotating cylindrical cavity filled with binary aqueous solution
Authors: Komatsu Yoshimi , Sugawara Masahiro , Matsukawa Seiichi , Fujita Tadashi 
Published: October 2008

AbstractThe melting of a vertical ice cylinder into a homogeneous calcium chloride aqueous solution inside a rotating cylindrical cavity with several rotating speeds is considered experimentally. The melting mass and temperature are measured on four initial conditions of the solution and four rotating speeds of the cavity. The temperature of the liquid layer becomes uniform by the mixing effect resulting from cavity rotation and it enhances the melting rate of the ice cylinder. As the cavity‐rotating speed increases, the melting rate increases. The dimensionless melting mass is related to the Fourier number and the rotating Reynolds number in each initial condition, therefore an experimental equation that is able to quantitatively calculate the dimensionless melting mass is presented. It is seen that the melting Nusselt numbers increase again in the middle of the melting process. The ice cylinder continues to melt in spite of the small temperature difference between the ice cylinder and the solution. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(6): 359–373, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20211
Neural network volatility forecasts
Authors: Aragonés José R. , Blanco Carlos , Estévez Pablo García 
Published: October 2008

AbstractWe analyse whether the use of neural networks can improve ‘traditional’ volatility forecasts from time‐series models, as well as implied volatilities obtained from options on futures on the Spanish stock market index, the IBEX‐35. One of our main contributions is to explore the predictive ability of neural networks that incorporate both implied volatility information and historical time‐series information. Our results show that the general regression neural network forecasts improve the information content of implied volatilities and enhance the predictive ability of the models. Our analysis is also consistent with the results from prior research studies showing that implied volatility is an unbiased forecast of future volatility and that time‐series models have lower explanatory power than implied volatility. Copyright © 2008 John Wiley & Sons, Ltd.