bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical and Experimental Investigations of the Suitability of Low‐Current Z‐Pinch Plasma as an Absorption Medium for Laser Radiation
Authors: Brückner S. , Wieneke S. , Viöl W.
Published: October 2008

In this study the electron density of z‐pinch plasmas driven at relatively low currents (ca. 2‐5 kA) was determined using only emission spectroscopy. The suitability of a hollow‐cathode‐triggered z‐pinch plasma as an absorption medium for laser radiation was investigated. The temporal and spatial behaviors of electron temperature and density profiles were estimated using magnetohydrodynamic (MHD) simulations to evaluate the experimental results. Temperature measurements were performed according to the Boltzmann plot method in the visible spectrum range, using the fact that, in low‐current z‐pinch plasma, a local thermodynamic equilibrium prevails for states at high principal quantum numbers (partial local thermodynamic equilibrium). In this case, the Saha equation can be used to determine the electron density. The results demonstrate that this method of determining the electron temperature and density of z‐pinch plasmas is only applicable during the pinching phase. However, in this case the experimentally determined values are in fairly good agreement with the values determined using the MHD model. A user‐oriented 1‐D radiation MHD code was used to simulate the dynamic evolution of the plasma. The experimentally determined maximum electron temperature of approximately 12 eV is in fairly good agreement with the simulated value. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cre recombinase activity specific to postnatal, premeiotic male germ cells in transgenic mice
Authors: Sadate‐Ngatchou Patricia I. , Payne Christopher J. , Dearth Andrea T. , Braun Robert E.
Published: October 2008

We have generated a transgenic mouse line,Tg(Stra8‐cre)1Reb (Stra8‐cre), which expresses improved Cre recombinase under the control of a 1.4 Kb promoter region of the germ cell‐specific stimulated by retinoic acid gene 8 (Stra8). cre is expressed only in males beginning at postnatal day (P)3 in early‐stage spermatogonia and is detected through preleptotene‐stage spermatocytes. To further define when cre becomes active, we crossed Stra8‐cre males with Tg(ACTB‐Bgeo/GFP)21Lbe (Z/EG) reporter females and compared the expression of enhanced green fluorescent protein (EGFP) with the protein encoded by the zinc finger and BTB domain containing 16 (Zbtb16) gene, PLZF—a marker for undifferentiated spermatogonia. Co‐expression of EGFP is observed in the majority of PLZF+ cells. We also tested recombination efficiency by mating Stra8‐cre;Z/EG males and females with wild‐type mice and examining EGFP expression in the offspring. Recombination is detected in >95% of Z/EG+ pups born to Stra8‐cre;Z/EG fathers but in none of the offspring born to transgenic mothers, a verification that cre is not functional in females. The postnatal, premeiotic, male germ cell‐specific activity of Stra8‐cre makes this mouse line a unique resource to study testicular germ cell development. genesis 46:738–742, 2008. © 2008 Wiley‐Liss, Inc.
Precipitation control over inorganic nitrogen import–export budgets across watersheds: a synthesis of long‐term ecological research
Authors: Kane E. S. , Betts E. F. , Burgin A. J. , Clilverd H. M. , Crenshaw C. L. , Fellman J. B. , Myers‐Smith I. H. , O'Donnell J. A. , Sobota D. J. , Van Verseveld W. J. , Jones J. B.
Published: October 2008

We investigated long‐term and seasonal patterns of N imports and exports, as well as patterns following climate perturbations, across biomes using data from 15 watersheds from nine Long‐Term Ecological Research (LTER) sites in North America. Mean dissolved inorganic nitrogen (DIN) import–export budgets (N import via precipitation–N export via stream flow) for common years across all watersheds was highly variable, ranging from a net loss of − 0·17 ± 0·09 kg N ha−1mo−1 to net retention of 0·68 ± 0·08 kg N ha−1mo−1. The net retention of DIN decreased (smaller import–export budget) with increasing precipitation, as well as with increasing variation in precipitation during the winter, spring, and fall. Averaged across all seasons, net DIN retention decreased as the coefficient of variation (CV) in precipitation increased across all sites (r2 = 0·48, p = 0·005). This trend was made stronger when the disturbed watersheds were withheld from the analysis (r2 = 0·80, p < 0·001, n = 11). Thus, DIN exports were either similar to or exceeded imports in the tropical, boreal, and wet coniferous watersheds, whereas imports exceeded exports in temperate deciduous watersheds. In general, forest harvesting, hurricanes, or floods corresponded with periods of increased DIN exports relative to imports. Periods when water throughput within a watershed was likely to be lower (i.e. low snow pack or El Niño years) corresponded with decreased DIN exports relative to imports. These data provide a basis for ranking diverse sites in terms of their ability to retain DIN in the context of changing precipitation regimes likely to occur in the future. Copyright © 2008 John Wiley & Sons, Ltd.
Wolves, trophic cascades, and rivers in the Olympic National Park, USA
Authors: Beschta Robert L. , Ripple William J.
Published: October 2008

Gray wolves (Canis lupus) were extirpated in the early 1900s from the Olympic Peninsula of northwestern Washington. Thus, we studied potential cascading effects of wolf removal by undertaking a retrospective study of Roosevelt elk (Cervus elaphus) populations, riparian forests, and river channel morphology. For three riparian sites within the western portion of Olympic National Park, the age structure of black cottonwood and bigleaf maple indicated a pattern of significantly decreased recruitment (growth of seedlings/sprouts into tall saplings and trees) associated with intensive elk browsing in the decades following the loss of wolves. At a riparian site outside the park, which represented a refugium from elk browsing, cottonwood recruitment has been ongoing during the 20th century, indicating that climate and flow regimes, in the absence of intensive herbivory, have not limited the establishment and growth of this deciduous woody species. Using 1994 orthophotos, we also measured channel dimensions and planform morphology of 8‐km‐long river reaches at each vegetation sampling site and an additional reach outside the park. Channels inside the park versus those outside the park had greater percent braiding (37 vs 2%) and larger ratios of active channel width/wetted width (3·0 vs 1·5 m/m). Results for western Olympic National Park were consistent with a truncated trophic cascade hypothesis whereby ungulate browsing following the extirpation of wolves caused significant long‐term impacts to riparian plant communities which, in turn, allowed increased riverbank erosion and channel widening to occur. Copyright © 2008 John Wiley & Sons, Ltd.
Hydroecological responses of the Athabasca Delta, Canada, to changes in river flow and climate during the 20th century
Authors: Wolfe Brent B. , Hall Roland I. , Edwards Thomas W. D. , Vardy Sheila R. , Falcone Matthew D. , Sjunneskog Charlotte , Sylvestre Florence , McGowan Suzanne , Leavitt Peter R. , van Driel Peter
Published: October 2008

We employ water‐isotope tracers and multi‐proxy paleolimnological records to characterize contemporary controls on water balances of floodplain lakes in the Athabasca Delta, Canada, within the context of its hydroecological evolution over the 20th century. The insight gained from these approaches is necessary to gauge the hydroecological resiliency of the Athabasca Delta to past and future changes in Athabasca River flow regime. Results obtained from three lakes located in different regions of the Athabasca Delta indicate that hydroecological conditions were strongly affected by an engineered meander cut‐off on the Athabasca River in 1972, intended to maintain flow in the river main stem, and a natural bifurcation of one of the major distributaries (Embarras River) in 1982, in response to progressive overextension of the delta to the east. Climate warming and naturally declining river discharge have also contributed to directional change. Recent drying trends reconstructed from sediment cores at two of the three lakes are likely representative of rapidly evolving hydroecological conditions in the south‐eastern sector, based on mapping of a recent high‐magnitude ice‐jam flood that failed to recharge this portion of the delta, while wetting in the region of the third lake due to increased frequency of river flooding reflects increasing diversion of Athabasca River flow northward. Our findings highlight the hydroecological sensitivity of the Athabasca Delta to changes in the magnitude and timing of discharge in the Athabasca River and heighten the need for informed management strategies to safeguard the integrity of this unique wetland ecosystem. Copyright © 2008 John Wiley & Sons, Ltd.
Ecosystem impacts of disturbance in a dry tropical forest in southern India
Authors: Mehta Vishal K. , Sullivan Patrick J. , Walter M. Todd , Krishnaswamy Jagdish , DeGloria Stephen D.
Published: October 2008

Indian forests provide a multitude of services to vast populations. Common human activities including livestock grazing, fuelwood extraction and burning have the potential to impact forest ecosystem structure and function. The effects of these activities on vegetation, ecology and soil properties were investigated in Bandipur National Park (BNP) in southern India. Data were collected from 200 sites in four watersheds within the park. Sample sites spanned a degradation gradient measured by a field disturbance index (FDI). This paper focusses on the impacts on vegetation structure, diversity and composition, and integrates impacts on soil. Shrub and tree species were inventoried and evaluated in plots 10‐m in diameter. The tree layer was dominated by Anogeissus–Emblica–Tectona species. The understory was dominated by invasives Chromolaena odorata and Lantana camara, and native Gymnosporia emarginata. Vegetation plot heights, canopy cover and tree diameters were negatively correlated with field disturbance resulting in stunted forest stature in degraded sites. Vegetation composition in degraded watersheds was dominated by small woody tree species and a greater diversity of shrub species. Ordination analysis was used to integrate soil data with vegetation and disturbance, revealing that deciduous forest in the park is degrading to scrub forest along with negative impacts on soil characteristics. Consequences of services currently enjoyed by local populations are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Impacts of disturbance on soil properties in a dry tropical forest in Southern India
Authors: Mehta Vishal K. , Sullivan Patrick J. , Walter M. Todd , Krishnaswamy Jagdish , DeGloria Stephen D.
Published: October 2008

Grazing, fuelwood extraction and burning are common human activities in Indian forests. These activities can represent forest disturbances that drive the degradation of natural deciduous forest cover to scrub forest, with concurrent impacts on soils. The effects of human forest use on ecosystem functions were investigated inBandipur National Park (BNP)in Peninsular India. This paper reports the impacts on surface soils. Soils were sampled from 200 locations covering four watersheds within the Park. These samples spanned a degradation gradient measured by a field disturbance index (FDI). Soil physical, nutrient and hydraulic properties were measured. Cation exchange capacity (CEC) and saturated hydraulic conductivity (Ks) were analyzed as key response variables describing nutrient availability and infiltration respectively. Effects of cattle and jeep trails on infiltration and bulk density were evaluated by sampling on‐and‐off trails. Trail density in research watersheds was estimated with satellite imagery. Soil nutrient availability is negatively impacted by disturbance, resulting from negative impacts on soil organic carbon (SOC) and clay content. Available water capacity (AWC) and saturated moisture content (SMC) were significantly higher in protected watersheds, attributed to reduced clay content in degraded watersheds. Off trails, high spatial variability in infiltration overwhelmed any meaningful trends with disturbance. However, infiltration was substantially reduced on trails as a result of significant increase in bulk density. The density of trails was considerably higher in degraded watersheds compared to protected watersheds. These results provide ground‐based and remotely sensed evidence that forest disturbance within the Park has negative impacts on soil organic matter, nutrient availability and hydraulic characteristics. These have consequences for related ecological, nutrient cycling and hydrological processes, and the continuation of the services currently enjoyed by local human populations. Copyright © 2008 John Wiley & Sons, Ltd.
Design of a naturalized flow regime—an example from the Lower Missouri River, USA
Authors: Jacobson Robert B. , Galat David L.
Published: October 2008

A group of river managers, stakeholders, and scientists met during summer 2005 to design a more naturalized flow regime for the Lower Missouri River (LMOR). The objective was to comply with requirements under the U.S. Endangered Species Act to support reproduction and survival of threatened and endangered species, with emphasis on the endangered pallid sturgeon (Scaphirhynchus albus), while minimizing negative effects to existing social and economic benefits of prevailing river management. Specific hydrograph requirements for pallid sturgeon reproduction are unknown, hence much of the design process was based on features of the natural flow regime. Environmental flow components (EFCs) extracted from the reference natural flow regime were used to design and assess performance of alternative flow regimes.

The design process incorporated a primary stage in which conceptual hydrographs were developed and assessed for their general ecological and social‐economic performance. The second stage accounted for hydroclimatic variation by coding the conceptual hydrographs into reservoir release rules, adding constraints for downstream flooding and low‐storage precludes, and running the rules through 100 years of hydroclimatic simulation. The output flow regimes were then evaluated for presumed ecological benefits based on how closely they resembled EFCs in the reference natural flow regime. Flow regimes also were assessed for social‐economic cost indicators, including days of flooding of low‐lying agricultural land, days over flood stage, and storage levels in system reservoirs.

Our experience with flow‐regime design on the LMOR underscored the lack of confidence the stakeholders place in the value of the natural flow regime as a measure of ecosystem benefit in the absence of fundamental scientific documentation. Stakeholders desired proof of ecological benefits commensurate with the certainty of economic losses. We also gained insight into the processes of integrating science into a collaborative management exercise. Although the 2005 collaborative effort failed to reach a consensus among stakeholders on a naturalized flow regime, the process was successful in pilot‐testing a design approach; it helped focus scienctific efforts on key knowledge gaps; and it demonstrated the potential for collaborations among scientists, stakeholders, and managers in river management decision making. Copyright © 2008 John Wiley & Sons, Ltd.
Manganese(II) Trimeric Systems Derived from Pyridyldioximato Ligands: Synthesis, Crystal Structure, and Magnetic Characterization
Authors: Escuer Albert , Cordero Beatriz , Solans Xavier , Font‐Bardia Mercé , Calvet Teresa
Published: October 2008

Three new manganese compounds have been obtained by reaction of the 2,6‐diacetylpyridine dioxime (dapdoH2) ligand with several MnII salts. By using a variety of manganese(II) carboxylates, three MnII derivatives with general formula [Mn3(RCOO)6(dapdoH2)2], where RCOO– = formate (1), acetate (2), and benzoate (3), were obtained. Structural analysis reveals chains of trinuclear units for 1 and isolated trinuclear molecules for 2. Compound 1 provides an example of a new topology for the [Mn3(RCOO)6(L)2] general formula. Magnetic susceptibility studies reveal topological ferrimagnetism for 1 and conventional antiferromagnetic response for 2 and 3, with coupling constants of –3.1, –3.2, and –1.4 cm–1 inside the trimeric units of 1, 2, and 3, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Functionalized Sugars as Ligands towards Water‐Soluble [Fe‐only] Hydrogenase Models
Authors: Apfel Ulf‐Peter , Halpin Yvonne , Gottschaldt Michael , Görls Helmar , Vos Johannes G. , Weigand Wolfgang
Published: October 2008

Only a small number of water‐soluble iron carbonyl type model compounds for the active centre in [Fe‐only] hydrogenase are known, and these models are mainly prepared by substitution of one of the CO ligands. In this publication we present new water‐soluble models for [Fe‐only] hydrogenase that contain a peripherally bound sugar residue. Compounds were prepared in which the 1,3‐disulfanyl‐2‐propyltetra‐O‐acetyl‐β‐D‐glucopyranoside unit is coordinated to the iron carbonyl core through either a sulfur or a selenium bridgehead atom. Electrochemical results for both types of compounds reveal hydrogen gas evolution from acetic acid and water. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Hydrogen Bonding in Crystalline Alcohol Solvates of the Platinum(II) Sulfido Complex [Pt2(μ‐S)2(PPh3)4]
Authors: Henderson William , Thwaite Simon , Nicholson Brian K. , Hor T. S. Andy
Published: October 2008

Suspension of [Pt2(μ‐S)2(PPh3)4] in lower alcohols results in recrystallisation, forming yellow to yellow‐orange microcrystals of the solvates [Pt2(μ‐S)2(PPh3)4]·nROH (R = Me, Et, nBu). The di‐ethanol solvate was characterised by means of a single‐crystal X‐ray diffraction study and 1H NMR spectroscopy. The structure consists of an ethanol molecule hydrogen‐bonded in an asymmetric bifurcated fashion to the {Pt2S2} group, with the second, disordered ethanol molecule involved in a cooperative hydrogen‐bonding interaction with the oxygen of the first ethanol. Thermogravimetric analysis shows that the alcohol is relatively easily lost, regenerating orange, unsolvated [Pt2(μ‐S)2(PPh3)4]. [Pt2(μ‐S)2(PPh3)4] readily dissolves in hexafluoro‐2‐propanol, yielding yellow crystals of [Pt2(μ‐S)2(PPh3)4]·6(CF3)2CHOH on evaporation. Characterisation by X‐ray diffraction shows that the structure contains a [Pt2(μ‐S)2(PPh3)4] hydrogen‐bonded to a single(CF3)2CHOH molecule, with the additional (CF3)2CHOH molecules forming a discrete hydrogen‐bonded pentameric cluster in the crystal.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
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

BiBr3 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

The 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

Following 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

The 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

A 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

A 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

The 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

In 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

One 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

The 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

We 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

Particle 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

Obtaining 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

This 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

This 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

A 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

The 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

We 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.
Effect of daily water treatment on hatchling sex ratios in a turtle with temperature‐dependent sex determination
Authors: LeBlanc Anne Marie , Wibbels Thane
Published: October 2008

Some previous studies indicate that the local hydric environment may influence sex determination in turtles with temperature‐dependent sex determination. In this study, the effect of a daily application of 0.77 mL of ddH20 per egg using an incubation temperature of 29.1°C was examined during the temperature‐sensitive period for two consecutive nesting seasons. This regimen yielded sex ratios of 11.8 and 11.1% male in control groups not receiving water supplementation, whereas daily water treatments resulted in sex ratios of 86.7 and 45.7% male during the 2006 and 2007 nesting seasons, respectively. The results indicate that daily water treatments significantly influenced sex ratios (P<0.001). In addition to providing insight on the physiology of sex determination, these results could have implications for studies predicting sex ratios from nests on natural nesting beaches that are periodically exposed to rain. J. Exp. Zool. 311A:68–72, 2009. © 2008 Wiley‐Liss, Inc.
Japanese medaka Hox paralog group 2: insights into the evolution of Hox PG2 gene composition and expression in the Osteichthyes
Authors: Davis Adam , Scemama Jean‐Luc , Stellwag Edmund J.
Published: October 2008

Hox paralog group 2 (PG2) genes function to specify the development of the hindbrain and pharyngeal arch‐derived structures in the Osteichthyes. In this article, we describe the cDNA cloning and embryonic expression analysis of Japanese medaka (Oryzias latipes) Hox PG2 genes. We show that there are only two functional canonical Hox genes, hoxa2a and b2a, and that a previously identified hoxa2b gene is a transcribed pseudogene, ψhoxa2b. The functional genes, hoxa2a and b2a, were expressed in developing rhombomeres and pharyngeal arches in a manner that was relatively well conserved compared with zebrafish (Danio rerio) but differed significantly from orthologous striped bass (Morone saxatilis) and Nile tilapia (Oreochromis niloticus) genes, which, we suggest, may be owing to effects of post‐genome duplication loss of a Hox PG2 gene in the medaka and zebrafish lineages. ψhoxa2b was expressed at readily detectable levels in several noncanonical Hox expression domains, including the ventral aspect of the neural tube, the pectoral fin buds and caudal‐most region of the embryonic trunk, indicative that regulatory control elements needed for spatio‐temporal expression have diverged from their ancestral counterparts. Comparative expression analyses showed medaka hoxa2a and b2a expression in the 2nd pharyngeal arch (PA2) beyond the onset of chondrogenesis, which, according to previous hypotheses, suggests these genes function redundantly as selector genes of PA2 identity. We conclude that Hox PG2 gene composition and expression have diverged significantly during osteichthyan evolution and that this divergence in teleosts may be related to lineage‐dependent differential gene loss following an actinopterygian‐specific whole genome duplication. J. Exp. Zool. (Mol. Dev. Evol.) 310B:623–641, 2008. © 2008 Wiley‐Liss, Inc.
Possible solar control on primary production along the Indian west coast on decadal to centennial timescale
Authors: Kurian Siby , Agnihotri Rajesh , Borole D. V. , Naqvi S. Wajih A. , Ferreira Ana M. , Vale Carlos
Published: October 2008

Using multiple geochemical proxies including specific biomarkers (dinosterol, phytol, stigmasterol and β‐sitosterol) measured in a high‐sedimentation rate core collected from the inner shelf (depth ∼45 m) off Goa (India), we reconstruct surface productivity, which is mainly controlled by the monsoon upwelling in this region, during the last ca. 700 a. Surface productivity appears to have varied in tandem with the Konkan–Goa rainfall and sunspot activity during the instrumental period (last 250 a). The productivity proxies also covary with the total solar irradiance reconstructed for the period beyond the instrumental era, within the considerable uncertainty of the age model. This suggests that solar forcing may control coastal upwelling intensity and biological productivity in the eastern Arabian Sea on decadal to centennial timescales. During the late Anthropocene (last ca. 50 a), steep increases in all four biomarkers indicate greatly enhanced productivity in response to high solar irradiance as well as anthropogenic inputs of nutrients. Copyright © 2008 John Wiley & Sons, Ltd.
Size‐dependent SERS enhancement of colloidal silver nanoplates: the case of 2‐amino‐5‐nitropyridine
Authors: Sant'Ana A. C. , Rocha T. C. R. , Santos P. S. , Zanchet D. , Temperini M. L. A.
Published: October 2008

Surface‐enhanced Raman scattering (SERS) spectra of 2‐amino‐5‐nitropyridine (ANP) adsorbed on colloidal silver triangular nanoplates were obtained using samples with different mean sizes and surface plasmon frequencies. The relative SERS enhancement factor for each sample was determined by the analysis of the normalized SERS excitation profiles of ANP vibrational modes for nanoplates in suspension, without aggregation. The SERS profiles are blue‐shifted in relation to the localized surface plasmon peak. The detailed characterization of both morphology and concentration of the samples in addition to a rigorous normalization of the SERS spectra allowed a quantitative correlation between the SERS profiles and the mean size of the nanoplates. This correlation indicated the existence of an optimum size of the nanoplates for maximum Raman enhancement. Copyright © 2008 John Wiley & Sons, Ltd.