bluuebunny/crossref_metadata_2025 huggingface dataset:
Reductive Activation of tripod Metal Compounds: Identification of Intermediates and Preparative Application
Authors: Mautz Jürgen , Heinze Katja , Wadepohl Hubert , Huttner Gottfried
Published: February 2008

[tripodCoCl2] {tripod = CH3C(CH2PPh2)3} when treated with KC8 in THF solution under an argon atmosphere produces a reactive species [“tripodCo0”] (A) which undergoes oxidative additions with stannanes, [tripodCo(H)2(SnBu3)] (4), formed, for example, by addition of Bu3SnH. Silanes, R3SiH, undergo the same type of reaction producing [tripodCo(H)2(SiR3)] (R = Et: 5a; R = Ph: 5b). The solid‐state structures of all the compounds [tripodCo(H)2(ER3)] (E = Si, R = Ph; E = Sn, R = Ph, Bu) are rather similar. While they contain six‐coordinate cobalt with the formal oxidation state of cobalt being +III the coordination geometry is not octahedral: the heteroelement E deviates from the position which it would have in octahedral coordination by around 40° while the other five ligands, three phosphorus and two hydrogen, have the expected interligand angles of around 90° and 180°, respectively. The deviation of the heteroelement E is such that it approaches the metal bonded hydrogen atoms leading to short H···E contacts of only about 190 pm (E = Si) and 230 pm (E = Sn), respectively. The generation of a reactive species [“tripodCo0”] (A) was transferred to the synthesis of a reactive tripodnickel(0) species by treating a THF solution of [(DME)NiBr2] with KC8 in the presence of tripod. This species reacts with two electron donor ligands L to produce the pseudo tetrahedral compounds [tripodNi(L)] {L = PPh3 (6), AsPh3 (7), cHexNC (8), tBuNC (9), C2H4 (10)}. The identity of the reactive nickel(0) species as unequivocally deduced from NMR experiments is [tripod4Ni3] (12). All compounds were characterised by the usual analytic techniques including X‐ray analysis where applicable.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Reductive Activation oftripodMetal Compounds: Preparative Application
Authors: Mautz Jürgen , Huttner Gottfried
Published: February 2008

Thetripodnickel(0) species [tripod4Ni3] (1) {tripod= CH3C(CH2PPPh2)3} is shown to undergo oxidative addition with disulfides or diselenides REER (E = S, Se, R =tBu, Ph) to produce [tripodNi(ER)] (2). Compounds2show pseudo tetrahedral coordination. They are paramagnetic with one unpaired electron per molecule. Their magnetic behaviour is almost that of an ideal Curie‐type magnet down to temperatures of 2 K. They undergo reversible one electron oxidation to the 16 valence electron species [tripodNi(ER)]+. The isoelectronic pseudo tetrahedral 16 valence electron cobalt species [tripodCo(ER)] (3) are obtained by reduction of CoCl2with KC8in the presence oftripodand subsequent reaction with REER (E = S, Se; R =tBu, Ph). They are paramagnetic with two unpaired electrons per molecule. They can be reversibly oxidised to the 15 valence electron compounds [tripodCo(ER)]+while their reduction to the 17 valence electron species [tripodCo(ER)]–, which would be isoelectronic to the stable compounds2, is not observed. Under appropriate conditions the reactions with REER do not result in the formation of3but yield [tripodCoECotripod] (4) by extrusion of sulfur and selenium from the substrate. Compounds4show a linear Co–E–Co framework with very short Co–E bonds (E = S: 205 pm; E = Se: 216 pm). They are members of a family of dimetallaheterocumulenic compounds [LnMEMLn] (E = main group element of groups III to VI) with a valence electron count of 36 electrons. Quantum chemistry predicts that the HOMO of such compounds should be a degenerated pair of mainly metal centred orbitals. Electrochemistry of4a, [tripodCoSCotripod], shows three quasi‐reversible oxidation steps in the range of –700 mV vs. SCE to 570 mV vs. SCE, which can be understood as metal centred oxidations. Three different types of crystals have been obtained for different types of pseudopolymorphs4a. The geometric parameters of the coordination compounds are almost equal in these pseudopolymorphic crystals. The real difference is the content of solvent molecules and, hence, the packing of the molecules. In the crystals of4acontaining no solvent the coordination compounds form close packed layers stacked on each other in an oblique way. In the crystals containing4a·DME a layer of solvent molecules separates each pair of layers of close packed molecules. In the crystal of4a·3DME a cuboctahedral cage of solvent molecules embedding each coordination compound separates the complex molecules from each other. The different types of crystals observed underpin the globular shape of4and the effective shielding power of thetripodligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis, Structure, and Optical Properties of a Contorted <110>‐Oriented Layered Hybrid Perovskite: C3H11SN3PbBr4
Authors: Li Yinyan , Zheng Guoli , Lin Jun
Published: February 2008

The <110>‐oriented perovskite is very rare in the hybrid perovskites family. In this work, an unusual layered <110>‐oriented hybrid perovskite, which is stabilized by a special organic ligand, 2‐(aminoethyl)isothiourea, has been obtained. This ligand combines a primary amine and a formamidine on the two ends of one molecule. Introduction of the special ligand brings about contorted inorganic sheets in the hybrid perovskite structure. The optical properties of the new <110>‐oriented perovskite were studied.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
New Germanium Complexes Containing Ligands Based on 4,6‐Di‐tert‐butyl‐N‐(2,6‐diisopropylphenyl)‐o‐iminobenzoquinone in Different Redox States
Authors: Piskunov Alexandr V. , Aivaz'yan Igor A. , Poddel'sky Andrey I. , Fukin Georgii K. , Baranov Evgenii V. , Cherkasov Vladimir K. , Abakumov Gleb A.
Published: February 2008

The exchange reaction of lithium o‐amidophenolate, (AP)Li2, derived from the reaction of 4,6‐di‐tert‐butyl‐N‐(2,6‐diisopropylphenyl)‐o‐iminobenzoquinone (imQ) with GeCl4 in hexane or thf leads to (AP)2Ge (1) (AP is a dianion of imQ). The latter was also obtained by the interaction of GeCl2·dioxane and (ISQ)Li in toluene (ISQ is a radical anion of imQ). The reaction of (AP)Li2 with GeCl2·dioxane in thf results in the formation of germylene 2, [(AP)Ge (2)], which reduces neutral imQ to give compound 1. The exposure of 1 in thf to anhydrous HCl in a 1:1 molar ratio leads to its o‐aminophenolato derivative, (AP)(APH)GeCl (3). Free imQ inserts into the Ge–H bond of (C6F5)3GeH in thf to give (C6F5)3Ge(APH) (4). It is another way of obtaining complexes with protonated ligands such as APH. Compound 3 can be easily oxidized by air to form the stable paramagnetic complex (AP)(ISQ)GeCl (5). Complexes 1 and 3–5 were structurally investigated by using single‐crystal X‐ray diffraction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Gas‐Phase Generation and Electronic Structure Investigation of Oxidovanadium Triisocyanate, OV(NCO)3
Authors: Ge Maofa , Wang Weigang , Yin Shi , Della Védova Carlos O.
Published: February 2008

Oxidovanadium triisocyanate was generated from the heterogeneous reaction of gaseous vanadium trichloride oxide with silver cyanate and studied for the first time in the gas phase. The reaction processes were studied in situ by ultraviolet photoionization mass spectrometry combined with quantum chemical calculations and ultraviolet photoelectron spectrometry. The geometric and electronic structures were characterized and discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Coordination and Supramolecular Chemistry of New Bis‐bidentate Schiff‐Base Ligands
Authors: Isola Mauro , Balzano Federica , Liuzzo Vincenzo , Marchetti Fabio , Raffaelli Andrea , Uccello Barretta Gloria
Published: February 2008

The coordination chemistry of a series of bis‐bidentate Schiff‐base ligands with NiII and CuII has been investigated. The ligands contain two N,O‐bidentate chelating salicylaldiminato units attached to polymethylene or α,α′‐ortho‐xylidene central spacers, through ether linkages at the 3‐position of the salicyl moieties. In this paper we present a series of seven new complexes displaying several novel structural types, three of which are crystallographically characterized. Among others, the double‐stranded helicates with the metal ions in the trans‐square‐planar geometry are of particular interest. The ortho‐xylidene ligand H2L8, like the analogue H2L7 previously reported by us, forms dinuclear double‐stranded helicates stable both in the solid state and in solution; in the case of the ligands H2L1–6, the nuclearity and the structural motif of the related complexes depend on the number (n) of methylene units in the bridge. When n = 3, 4, thermodynamically stable products from their reaction with NiII and CuII are oligomeric or polymeric species, while under kinetic control novel supramolecular architectures become accessible. The NiII complexes of the ligands with n = 5, 6, 8 exist as dinuclear double‐stranded helicates in the solid state, while in solution they exhibit a monomer–dimer interconversion process, which has been studied using Diffusion Ordered Spectroscopy (DOSY). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Hydrogen Bonding and Lewis Acid–Base Interactions in the System Bis(pentafluorophenyl)borinic Acid / Methanol
Authors: Donghi Daniela , Maggioni Daniela , Beringhelli Tiziana , D'Alfonso Giuseppe , Mercandelli Pierluigi , Sironi Angelo
Published: February 2008

Methanol does not significantly affect the position and the rate of the equilibrium between the monomeric (1m) and cyclic trimeric (1t) forms of bis(pentafluorophenyl)borinic acid, Ar2BOH (1, Ar = C6F5), in CD2Cl2 solution. This contrasts with what was previously observed in the presence of thf and is mainly due to the stabilization of the 1m·MeOH covalent adduct through the formation of the hydrogen‐bonded dimer [Ar2B(OH)(MeOH)]2 (7), characterized in solution and by single‐crystal X‐ray analysis. This dimer can be viewed as the intermediate in the conversion of 1 into its methyl ester 6 by fast proton transfer along the hydrogen bond, which transforms the 1m·MeOH adduct into the 6·H2O adduct. Extrusion of H2O by water scavengers drives the equilibrium toward ester 6. X‐ray analysis showed that, at variance with 1, ester 6 in the solid state is a monomer. Hindered rotation [ΔH# = 38(1) kJ mol–1, ΔS# = –35(6) J mol–1] around the B–OMe bond, due to O‐to‐B π‐donation, has been observed. This π‐donation lowers the Lewis acidity of 6, as shown by the thermal instability of its adducts with MeOH and thf. Water addition to 6 affords the dimeric adduct 7, in fast equilibrium with both 1m and 6, even at 183 K, as revealed by 2D EXSY analysis. Borinic acid itself can act as a water scavenger at low temperature, so that 6 is formed also in the early stages of the titration of 1 with MeOH. The other main initial product was the adduct [Ar2B(OH)]3·MeOH (3) containing a MeOH molecule bound within an octaatomic –B–O(H)–B–O(Me)–H···O(H)–B–O(H)– ring. Fast proton transfer along the strong hydrogen bond was revealed by 2D EXSY analysis. At variance with thf, the adduct containing MeOH exocyclically hydrogen‐bonded to 1t could be obtained in high concentration at 183 K only when due allowance for the kinetic requirements of the slow trimerization equilibrium was made.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Oxidative Addition of B–Br Bonds to Pd0: Synthesis and Structure of trans‐Bromo(boryl)palladium Complexes
Authors: Braunschweig Holger , Gruss Katrin , Radacki Krzysztof , Uttinger Katharina
Published: February 2008

The oxidative addition of several bromoboranes to the Pd0 species [Pd(PCy3)2] yielded the novel palladium boryl complexes trans‐[(Cy3P)2Pd(Br)(BCat)] (1) (Cat = 1,2‐dioxophenylene), trans‐[(Cy3P)2Pd(Br)(BCat′)] (2) (Cat′ = Cat‐4‐tBu) and trans‐[(Cy3P)2Pd(Br){B(X)X′}] {X = Br, X′ = NMe2 (3), Pip (4) (Pip = NC5H10), Mes (5) [Mes = 2,4,6‐(CH3)3C6H2]}. Compounds 1–5 were characterized by multinuclear NMR spectroscopy in solution; single crystals for X‐ray analyses were acquired from 2 and 3, which thus allowed comparison of the structural data. The few palladium boryl complexes published so far were obtained by σ‐bond metathesis; the oxidative addition of the corresponding bromoboranes to Pd0 has not yet been reported.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Supramolecular Isomerism in Coordination Polymers of Isophthalato‐Bridged MnII Complexes Using 4,4′‐Dipyridyl N,N′‐Dioxide
Authors: Manna Subal Chandra , Zangrando Ennio , Ribas Joan , Ray Chaudhuri Nirmalendu
Published: February 2008

A one‐pot reaction of three components [MnII, isophthalate dianion (isop) and 4,4′‐dipyridyl N,N′‐dioxide (dpyo)] in water/methanol (1:1) causes self‐assembly resulting in two 3D supramolecular isomers of the same stoichiometry, {[Mn(isop)(H2O)2]·(dpyo)·(H2O)}n (colorless) (1) and {[Mn(isop)(H2O)(dpyo)0.5]·(dpyo)0.5·(H2O)2}n (pink) (2). Both isomers crystallize in the same crystal system (triclinic) and space group (P$\bar {1}$). The structural determination of 1 reveals an isophthalato‐bridged 1D coordination polymer, {[Mn(isop)(H2O)2]n, having 16‐ and 8‐membered rings where isophthalate acts simultaneously as chelating and bridging ligand connected to three metal centers. In isomer 2 the 1D chains transform to a 2D arrangement through bridging dpyo that replaces a water molecule at metal axial position. Both the crystal structures result in a 3D supramolecular network achieved through H‐bonding among the 1D (in 1) or 2D (in 2) coordination polymers with lattice water and dpyo molecules and also by means of π‐π interactions in 1. Low‐temperature magnetic measurement indicates antiferromagnetic interaction in both the isomers and the best fits are given by the exchange parameters J = –0.56 ± 0.02 cm–1, g = 2.01 ± 0.01 and R = 3.1 × 10–5 for 1 and J = –1.06 ± 0.03 cm–1, g = 2.01 ± 0.01 and R = 2.8 × 10–5 for 2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Guanosine Analog with Respect to Z‐DNA Stabilization: Nucleotide with Combined C8‐Bromo and C2′‐Ethynyl Modifications
Authors: Nadler André , Diederichsen Ulf
Published: February 2008

The stabilization of left‐handed Z‐DNA double strands by chemical modifications is especially of interest regarding investigations of its biological role. Incorporation of modified nucleotide building blocks in DNA allows recognition studies under physiological conditions without the need for a Z‐DNA inducing environment. Approaches to enforce the Z‐DNA double helix using guanosine derivatives are the introduction of sterically demanding groups at guanine C8 or of 2′‐ribosyl substitutions determining the ribosyl conformation. 8‐Bromo‐2′‐ethynyl‐arabino‐deoxyguanosine was synthesized as phosphoramidite building block. Incorporated in suitable oligonucleotides the potential to induce the Z‐form DNA was investigated by CD spectroscopy. With a nucleotide containing the 8‐bromo and the 2′‐ethynyl group a synergistic effect of the two modifications was expected to provide stronger stabilization of Z‐DNA. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Design, Synthesis, and Spectral Luminescent Properties of a Novel Polycarbocyanine Series Based on the 2,2‐Difluoro‐1,3,2‐dioxaborine Nucleus
Authors: Zyabrev Konstantin , Doroshenko Andrey , Mikitenko Elena , Slominskii Yurii , Tolmachev Alexei
Published: February 2008

The natures of the chromophores in symmetric polymethine dyes derived from 2,2‐difluoro‐1,3,2‐dioxaborine have been investigated. Ab initio quantum chemical calculations demonstrated that the presence of dioxaborine end residues stabilizes the frontier levels of the corresponding polymethine dye and makes electron‐density distribution over the oxygen atoms in the chelate ring more even than in the analogous dye structure with boron‐free acyclic end groups. A series of novel symmetric polycarbocyanines and a tricarbocyanine series with variously bridged polymethine chromophores have been synthesized from hitherto unknown pyrimidino‐annelated dioxaborines. The absorption, fluorescence and 13C NMR spectroscopic data point to the polymethinic type of electron‐density distribution in the 2,2‐difluoro‐1,3,2‐dioxaborine polymethine dye molecules. The fundamental options for controlling the spectral properties of these dyes by modification of their polymethine chains have been evaluated. One of the new compounds synthesized is remarkable among the known open‐chain polymethine dyes for its record high fluorescence quantum yield. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
(E,E,E)‐4,4′‐Distyrylstilbenes – Synthesis, Photophysics, Photochemistry and Phase Behavior
Authors: Meier Herbert , Lifka Thorsten , Stalmach Ulf , Oehlhof Annette , Prehl Sabine
Published: February 2008

The fluorescence quantum yields F(n) of oligo[2,5‐bis(propyloxy)‐1,4‐phenylenevinylene]s (1b) reach for the trimer (n = 3) in solution a maximum of 86 %, which is almost twice as high as for the monomer (n = 1) and the octamer or undecamer (n = 8, 11). The latter represent the convergence limit of 46 %. 4‐Mono‐, 3,4‐di‐ or 3,4,5‐trisubstituted terminal phenyl rings in the trimers 6a–f do not lead to calamitic or phasmidic liquid crystals; however, 2,3,4‐trisubstitution with hexyloxy groups (6h) and even with OCH3 groups (6g) effects LC formation. Irradiation with energy‐rich UV light provokes a crosslinking of the originally conjugated chains. In the case of 6c, a chemo‐ and stereoselective [2π + 2π] photocycloaddition could be established as well.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Stereoselective Access to Substituted [(E)‐ or (Z)‐1‐(Trifluoromethyl)allyl]amines
Authors: Magueur Guillaume , Crousse Benoit , Bonnet‐Delpon Danièle
Published: February 2008

Hydrometallation reactions, for example, hydroboration and hydroalumination, on [1‐(trifluoromethyl)propargyl]amines lead stereoselectively to the corresponding [(Z)‐ and (E)‐1‐(trifluoromethyl)allyl]amines in good yields; (Z)‐ and (E)‐allylamines with a free amino group can be obtained in good yields and excellent enantioselectivities from the chiral propargylamines.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Non‐Natural Aromatic α‐Amino Acids by a Heck Reaction
Authors: Suhartono Marcel , Weidlich Markus , Stein Torsten , Karas Michael , Dürner Gerd , Göbel Michael W.
Published: February 2008

Alkene 3, a TBS‐ and Cbz‐protected derivative of vinylglycinol, safely available from methionine, undergoes efficient Heck coupling reactions in high yields. The resulting products can be converted into enantiopure α‐amino acids with aromatic and heteroaromatic side‐chains. Compound 6a, a brightly fluorescent Fmoc‐protected pyrene amino acid is of special interest. Tripeptide 8a, composed of this building block and two arginines, binds to TAR, an RNA element regulating transcriptional efficiency in HIV, with a Kd value of 50 nM. This compound also inhibits a coupled cell‐free transcription‐translation assay (IC50 = 40 μM) and shows pronounced antibacterial activity against B. subtilis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A bivariate stochastic Gompertz diffusion model: statistical aspects and application to the joint modeling of the Gross Domestic Product and CO2 emissions in Spain
Authors: Gutiérrez R. , Gutiérrez‐Sánchez R. , Nafidi A.
Published: February 2008

In this paper we propose a bivariate stochastic Gompertz diffusion model as the solution for a system of two Itô stochastic differential equations (SDE) that are similar as regards the drift and diffusion coefficients to those considered in the univariate Gompertz diffusion model, which has been the object of much study in recent years. We establish the probabilistic characteristics of this model, such as the bivariate transition density, the bidimensional moment functions, the conditioned trend functions and in particular, the correlation function between each of the components of the model. We then go on to study the maximum likelihood estimation of the bidimensional drift and the diffusion matrix of the diffusion in question, proposing a computational statistical methodology for this purpose based on discrete observations over time, for both components of the model. By these means we are able to achieve the maximum likelihood estimation of the trend and correlation functions and thus establish a method for trend analysis, which we apply to the real case of two dependent variables, Gross Domestic Product (GDP) and CO2 emission in Spain, the joint dynamic evolution of which is modeled by the proposed Gompertz bidimensional model. This implementation is carried out on the basis of annual observations of the variables over the period 1986–2003. The application is a new methodology in environmental and climate change studies, and provides an alternative to other approaches of a more econometric nature, or those corresponding to the methodology of secular trends in Time Series. Copyright © 2008 John Wiley & Sons, Ltd.
Smoothing and bootstrapping the PROMETHEUS fire growth model
Authors: Garcia Tanya , Braun John , Bryce Robert , Tymstra Cordy
Published: February 2008

The PROMETHEUS model is a spatially explicit, deterministic fire growth model, praised for being beneficial in various aspects of fire management. Our goal is to build on this success, applying statistical smoothing to alleviate some computational difficulties and to increase accuracy; a pleasant by‐product is the opportunity to introduce stochasticity to the model using a residual‐based block bootstrap. Copyright © 2008 John Wiley & Sons, Ltd.
Structural composition and sediment transfer in a composite cirque glacier: Glacier de St. Sorlin, France
Authors: Roberson Sam
Published: February 2008

This paper considers the links between structure, sediment transport and sediment delivery at Glacier de St. Sorlin, France. Sediment transported by the glacier is concentrated at flow‐unit boundaries as medial moraines, controlled by the position of bedrock outcrops in the accumulation area. Rockfall entrained within primary stratification is tightly folded at flow‐unit boundaries under high cumulative strains and laterally compressive stress. High cumulative strains and laterally compressive stresses lead to the development of longitudinal foliation from primary stratification. Folding elevates subglacial sediments into foliation‐parallel debris ridges, which are exposed in the ablation area. Crevasses and shear planes within the glacier have little control on sediment transport. Debris stripes in the proglacial area are morphologically similar to foliation‐parallel debris ridges; however, they are not structurally controlled, but formed by fluvial erosion. The conclusion of this study is that at Glacier de St. Sorlin proglacial sediment‐landform associations are subjected to intense syn‐ and post‐depositional modification by high melt‐water discharges, hence their composition does not reflect that of sediments melting out at the terminus. The action of melt water limits the potential of the sedimentary record to be used to constrain numerical models of past glacier dynamics in debris‐poor glacierized Alpine catchments. Copyright © 2008 John Wiley & Sons, Ltd.
A mass balance approach to quantifying Pb storage and fluxes in an upland catchment of the Peak District, north‐central England
Authors: Shotbolt L. A. , Rothwell J. J. , Lawlor A. J.
Published: February 2008

A mass balance model of the main Pb stores and fluxes for a typical organic‐rich upland catchment in the Peak District, UK, has been produced. The model, based on the Howden reservoir catchment, reveals that the majority of Pb in the catchment is stored within the soil (approximately 8·63 t km−2). Soil Pb levels are extremely high and can only be explained as the result of centuries of atmospheric Pb deposition from surrounding urban–industrial conurbations, and mining and smelting activity within the Peak District National Park. The atmospheric Pb flux onto the Howden catchment is approximately 107 kg a−1. The aquatic Pb flux is estimated at between 29·9 and 71·7 kg a−1; thus, at present, catchment soils are acting as a sink for Pb pollution. The Howden reservoir acts as a secondary store for Pb eroded and leached from catchment soils, with approximately 80% re‐deposited in its sediments. It is estimated that 2·3% of the catchment soil Pb pool has been retained in the reservoir sediments over its 91 year lifespan.

Although the catchment is currently acting as a Pb sink, the rate of change in the soil Pb pool is very small. Future change in climate or deposition chemistry could, however, transform catchment soils into a significant source of Pb to the aquatic environment and water supply. Copyright © 2008 John Wiley & Sons, Ltd.
Price discovery in the options markets: An application of put‐call parity
Authors: Hsieh Wen‐Liang G. , Lee Chin‐Shen , Yuan Shu‐Fang
Published: February 2008

This study investigates the relative rate of price discovery in Taiwan between index futures and index options, proposing a put‐call parity (PCP) approach to recover the spot index embedded in the options premiums. The PCP approach offers the benefits of reducing model risk and alleviating the burden of volatility estimation. Consistent with the trading‐cost hypothesis, a dominant tendency is found for futures and a subordinate but non‐trivial price discovery from options. The relative weight of options price discovery is sensitive to the methodology employed as the means of inferring the option‐implicit spot price. The empirical evidence suggests that the information contained in the PCP‐implied spot encompasses that provided by the Black‐Scholes‐implied spot. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28:354– 375, 2008
Efficiency of the IBEX spot–futures basis: The impact of the mini‐futures
Authors: McMillan David G. , Garcia Raquel Quiroga
Published: February 2008

This paper considers whether the introduction of the mini‐futures contract for the Spanish Ibex index affects overall market efficiency. Using linear, non‐linear, and fractional integration modeling techniques for the basis term, results of this study suggest the following salient points. First, the equilibrium speed of adjustment is reduced after the introduction of the mini‐futures contract. This effect is particularly pronounced in the mini‐futures second year when its contracts are more heavily traded. Second, fractional integration tests support longer memory in the basis term after the contract introduction, again particularly in the second year. Third, the relationship between the full‐size and mini‐futures contracts appears highly efficient, with a quick speed of adjustment and short memory. Finally, an examination of the volatility dynamics suggests that in the second year of the mini‐futures contract shocks to spot return volatility exhibit longer memory. The results reported here suggest that the increased use of the mini‐futures contract after its introduction has had a detrimental impact on price discovery. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28: 398–415, 2008
Intraday volatility in the bond, foreign exchange, and stock index futures markets
Authors: Martinez Valeria , Tse Yiuman
Published: February 2008

Intraday volatility for the Eurodollar, the Euro/dollar foreign exchange rate, and the E‐mini S&P 500 futures contracts traded on a continuous 23‐hour schedule on the Chicago Mercantile Exchange Globex electronic platform is studied. Volatility transmission in a single market across different regions is mainly explained by intraregion volatility (heat waves); interregion volatility (meteor showers) plays a secondary role. The joint impact of liquidity variables such as volume and open interest on volatility is also analyzed. Volume tends to increase volatility, but open interest does not affect it. The results are explained by the type of trading venue. Unlike floor‐based trading systems, in electronic markets open interest does not seem to provide additional information on market liquidity and its relation to volatility beyond any information contributed by volume. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28:313– 334, 2008
Raman and FTIR microscopic imaging of colon tissue: a comparative study
Authors: Krafft Christoph , Codrich Daniela , Pelizzo Gloria , Sergo Valter
Published: February 2008

Colon tissue constitutes a valid model for the comparative analysis of soft tissue by Raman and Fourier transform infrared (FTIR) imaging because it contains four major tissue types such as muscle tissue, connective tissue, epithelium and nerve cells. Raman microscopic images were recorded in the mapping mode using 785 nm laser excitation and a step size of 10 μm from three regions within a thin section that encompassed mucus, mucosa, submucosa, and longitudinal and circular muscle layers. FTIR microscopic images that were composed of 4, 8 and 9 individual images of 4096 spectra each were recorded from the same regions using a FTIR spectrometer coupled to a microscope with a focal plane array detector. Furthermore, Raman microscopic images were recorded at a step size of 2.5 μm from three ganglia that belong to the myenteric plexus. The results are discussed with respect to lateral resolution, spectral resolution, acquisition time and sensitivity of both modalities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fluorescent proteins for single‐molecule fluorescence applications
Authors: Seefeldt Britta , Kasper Robert , Seidel Thorsten , Tinnefeld Philip , Dietz Karl‐Josef , Heilemann Mike , Sauer Markus
Published: February 2008

We present single‐molecule fluorescence data of fluorescent proteins GFP, YFP, DsRed, and mCherry, a new derivative of DsRed. Ensemble and single‐molecule fluorescence experiments proved mCherry as an ideally suited fluorophore for single‐molecule applications, demonstrated by high photostability and rare fluorescence‐intensity fluctuations. Although mCherry exhibits the lowest fluorescence quantum yield among the fluorescent proteins investigated, its superior photophysical characteristics suggest mCherry as an ideal alternative in single‐molecule fluorescence experiments. Due to its spectral characteristics and short fluorescence lifetime of 1.46 ns, mCherry complements other existing fluorescent proteins and is recommended for tracking and localization of target molecules with high accuracy, fluorescence resonance energy transfer (FRET), fluorescence lifetime imaging microscopy (FLIM), or multicolor applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A subcelluar proteomic investigation into vincristine‐resistant gastric cancer cell line
Authors: Yang Yi‐Xuan , Chen Zhu‐Chu , Zhang Gui‐Ying , Yi Hong , Xiao Zhi‐Qiang
Published: February 2008

Multidrug resistance (MDR) is a major obstacle to successful cancer treatment. To understand the mechanism of MDR better, a subcelluar proteomics approach was used to compare the protein profile between vincristine‐resistant human gastric cancer cell line SGC7901/VCR and its parental cell line SGC7901. After differential solubilization, the subfractionation proteins were separate by two‐dimensional gel electrophoresis (2‐DE), and the differential protein spots were identified by both MALDI‐TOF‐MS and ESI‐Q‐TOF‐MS. Then the differential expressional levels of partial identified proteins were determined by Western blot analysis. Furthermore, one of the highly expressed proteins in SGC7901/VCR, Sorcin, associated with MDR was analyzed. In this study, the well‐resolved, reproducible 2‐DE patterns of subfractionation proteins from SGC7901/VCR and SGC7901 were established, and 30 differential proteins between the two cell lines were identified. The functional validation showed that the elevated sorcin expression could contribute considerably to the vincristine resistance in SGC7901/VCR. The 30 differentially expressed proteins could be divided into six groups based on their functions: calcium binding proteins, chaperones, metabolic enzymes, proteins relative to signal transduction, proteins involved in transcription and translation, and transportation proteins, and most of them might be new MDR associated proteins, which have not been detected previously. These data will be valuable for further to study the mechanisms of MDR in human gastric cancer. J. Cell. Biochem. 104: 1010–1021, 2008. © 2008 Wiley‐Liss, Inc.
NF‐κB and epithelial to mesenchymal transition of cancer
Authors: Min Chengyin , Eddy Sean F. , Sherr David H. , Sonenshein Gail E.
Published: February 2008

During progression of an in situ to an invasive cancer, epithelial cells lose expression of proteins that promote cell–cell contact, and acquire mesenchymal markers, which promote cell migration and invasion. These events bear extensive similarities to the process of epithelial to mesenchymal transition (EMT), which has been recognized for several decades as critical feature of embryogenesis. The NF‐κB family of transcription factors plays pivotal roles in both promoting and maintaining an invasive phenotype. After briefly describing the NF‐κB family and its role in cancer, in this review we will first describe studies elucidating the functions of NF‐κB in transcription of master regulator genes that repress an epithelial phenotype. In the second half, we discuss the roles of NF‐κB in control of mesenchymal genes critical for promoting and maintaining an invasive phenotype. Overall, NF‐κB is identified as a key target in prevention and in the treatment of invasive carcinomas. J. Cell. Biochem. 104: 733–744, 2008. © 2008 Wiley‐Liss, Inc.
Effects of basic fibroblast growth factor on endothelial cells under conditions of simulated microgravity
Authors: Ulbrich Claudia , Westphal Kriss , Baatout Sarah , Wehland Markus , Bauer Johann , Flick Burkhard , Infanger Manfred , Kreutz Reinhold , Vadrucci Sonia , Egli Marcel , Cogoli Augusto , Derradji Hanane , Pietsch Jessica , Paul Martin , Grimm Daniela
Published: February 2008

Fibroblast growth factors interact with appropriate endothelial cell (EC) surface receptors and initiate intracellular signal cascades, which participate in modulating blood vessel growth. EC, upon exposure to basic fibroblast growth factors (bFGFs) undergo profound functional alterations, which depend on their actual sensitivity and involve gene expression and de novo protein synthesis. We investigated the effects of bFGF on signaling pathways of EA.hy926 cells in different environments. EC were cultured under normal gravity (1 g) and simulated microgravity (µg) using a three‐dimensional (3D) clinostat. Microgravity induced early and late apoptosis, extracellular matrix proteins, endothelin‐1 (ET‐1) and TGF‐β1 expression. Microgravity reduced eNOS mRNA within 24 h. Moreover, a six‐ to eightfold higher amount of IL‐6 and IL‐8 was secreted within 24 h µg. In addition, microgravity induced a duplication of NF‐kappaB p50, while p65 was quadrupled. At 1 g, bFGF application (4 h) reduced ET‐1, TGF‐β1 and eNOS gene expression. After 24 h, bFGF enhanced fibronectin, VEGF, Flk‐1, Flt‐1, the release of IL‐6, IL‐8, and TGF‐β1. Furthermore, bFGF promoted apoptosis, reduced NFkB p50, but enhanced NFkB p65. After 4 h µg, bFGF decreased TGF‐β1, eNOS, and ET‐1 gene expression. After 24 h µg, bFGF elevated fibronectin, Flk‐1 and Flt‐1 protein, and reduced IL‐6 and IL‐8 compared with vehicle treated µg cultures. In µg, bFGF enhanced NF‐KappaB p50 by 50%, Bax by 25% and attenuated p65, activation of caspase‐3 and annexin V‐positive cells. bFGF differently changes intracellular signals in ECs depending whether it is applied under microgravity or normal gravity conditions. In microgravity, bFGF contributes to protect the EC from apoptosis. J. Cell. Biochem. 104: 1324–1341, 2008. © 2008 Wiley‐Liss, Inc.
Hydrolysis of Tifton 85 bermudagrass in a pressurized batch hot water reactor
Authors: Brandon Sarah K , Eiteman Mark A , Patel Krishna , Richbourg Michele M , Miller David J , Anderson William F , Doran Peterson Joy
Published: February 2008

BACKGROUND: Ethanol production from grass is desirable due to the large amount of biomass it produces. However, a pretreatment is necessary before fermentation to increase ethanol yield. Tifton 85 bermudagrass was treated with a newly designed pressurized batch hot water reactor. Multiple temperatures, pressures, and reaction times were evaluated, and reducing sugars liberated during enzymatic hydrolysis were determined.

RESULTS: Pressure had a negligible effect on digestibility of the grass, and a reaction temperature of 230 °C for 2 min was the most effective in releasing reducing sugars. Fermentations were conducted with untreated grass and with grass treated for 2 min at 200 °C or 230 °C to confirm that the increase in reducing sugar concentration resulted in an increased ethanol yield. Following hydrolysis with 2 filter paper units (FPU) of a mixed cellulase enzyme cocktail per gram dry weight of grass, fermentations were performed with engineered Escherichia coli strain LY01. Grass treated at 230 °C produced 14.7 g L−1 of ethanol, which was significantly higher than 200 °C treated grass (11.0 g L−1) and untreated grass (9.0 g L−1). Ferulic and para‐coumaric acids were also released during the fermentations.

CONCLUSION: Pressurized batch hot water reactor pretreatment is effective in increasing ethanol yield of grass in fermentations. Copyright © 2008 Society of Chemical Industry
Long‐term performance of co‐metabolic degradation of trichloroethylene in a fluidized bed reactor fed with benzene, toluene and xylene
Authors: Wu Wei‐Min , Shi Jing , Hickey Robert F
Published: February 2008

BACKGROUND: Trichloroethylene (TCE) can be degraded under aerobic condition with toluene and other aromatic compounds. Inhibition by primary substrates and toxicity of TCE oxidation influence TCE degradation.

RESULTS: Long‐term co‐metabolic degradation of TCE was evaluated using a laboratory‐scale fluidized bed reactor (12 L) with granular activated carbon (1.57 kg) as media and activated sludge as inoculum. The reactor was fed with TCE and a mixture of benzene, toluene and xylene (BTX) and operated with one‐pass (hydraulic retention time (HRT) of 5–6 min) for 6 months and then with recirculation (HRT of 20–30 min) for 18 months. BTX/TCE‐degrading biofilm was developed within 1 month. TCE was effectively degraded with influent TCE concentrations from 48 to 280 µg L−1. BTX inhibited TCE degradation. Recirculation (or long HRT) increased TCE removal efficiency from 30% with one‐pass to 90%. BTX/TCE load ratio influenced TCE removal efficiency and TCE/BTX removal ratio. TCE degradation fitted first‐order kinetics. The biomass grown in the reactor also degraded cis‐1,2‐dichloroethylene (DCE), trans‐1,2‐DCE and vinyl chloride efficiently except for 1,1‐DCE.

CONCLUSION: Co‐metabolic degradation of TCE by BTX‐degrading biomass from activated sludge is sustainable in the long term. BTX/TCE load ratio is a key parameter for TCE removal performance. Copyright © 2008 Society of Chemical Industry
Enantioseparation with D‐Phe‐ and L‐Phe‐imprinted PAN‐based membranes by ultrafiltration
Authors: Ul‐Haq Noaman , Khan Taous , Park Joong Kon
Published: February 2008

BACKGROUND: Solute rejection by a molecularly imprinted membrane was observed for the first time. Enantioselective poly[(acrylonitrile)‐co‐(acrylic acid)] membranes were prepared by a wet‐phase inversion method using D‐phenylalanine (D‐Phe) and L‐phenylalanine (L‐Phe) as templates, separately, in order to compare the imprinting effects of these isomers using an ultrafiltration experiment.

RESULTS: Recognition sites were successfully created in the prepared membranes, which had a nanoporous structure. The rejection selectivities of 0.13 and 0.28, adsorption selectivities of 2.25 and 2.40 and permselectivities of 1.94 and 2.08 were achieved for the D‐ and L‐Phe‐imprinted membranes, respectively, after 16 mL (34 min) of ultrafiltration.

CONCLUSION: Solute rejection by a molecularly imprinted membrane was selective. The performance characteristics of both the D‐ and L‐Phe‐imprinted membranes were different. Thus, the selection of an appropriate stereoisomer as a template plays an important role in the imprinting of membranes with regard to chiral resolution by ultrafiltration. Copyright © 2008 Society of Chemical Industry
Integrated xylitol production by fermentation of hardwood wastes
Authors: Ko Chun‐Han , Chiang Po‐Neng , Chiu Pei‐Chun , Liu Chia‐Chen , Yang Chin‐Lin , Shiau Ing‐Luen
Published: February 2008

BACKGROUND: In an effort to obtain higher‐value‐added derivatives, a process, starting with acid hydrolysis pretreatment of waste wood followed by fermentation and ultrafiltration, for production of xylitol from pulp mill hardwood wastes was developed and is reported here.

RESULTS: Sequential removals of furfural, 5‐hydroxymethylfurfural, total phenols and acetic acid were performed with powdered activated carbon and cationic ion exchange columns for the neutralized hydrolysate. Batch fermentations with yeast extract and detoxified and concentrated hydrolysates were conducted using Candida tropicalis (BCRC 20520), Candida boidinii (BCRC 21432), Candida guilliermondii (BCRC 21549), Candida utilis (BCRC 20334) and Pichia anomala (BCRC 21359). Among the yeast strains, C. tropicalis exhibited the highest volumetric rates of product generation (QP, 0.73 g L−1 h−1) and substrate consumption (QS, 1.35 g L−1 h−1) over 44 h. Additional C. tropicalis fermentation runs achieved product yield (YP/S) values of 0.70 and 0.45 g g−1 after 96 h with urea and soybean meal respectively. Between 9.59 and 25.51 g L−1 of ethanol was also produced in these systems. Pretreatment with 2 mg L−1 polydiallyldimethylammonium chloride on the membrane surface increased protein rejection from 85 to 96% for fermentation broth in a 2 h span.

CONCLUSION: The present study demonstrates that xylitol, a value‐added derivative, can be effectively obtained from hardwood wastes using low‐cost fermentation media. Copyright © 2008 Society of Chemical Industry
Extraction of components of composite materials: ionic liquids in the extraction of flame retardants from plastics
Authors: Lateef Huma , Grimes Susan M , Morton Roger , Mehta Lina
Published: February 2008

BACKGROUND: The presence of certain polybrominated flame retardants in electrical and electronic equipment plastics can make recycling of the raw materials difficult. We have investigated the use of ionic liquids to selectively remove these harmful components and a series of imidazolium‐ and pyridinium‐based ionic liquids have been prepared in a microwave reactor. Microwave synthesis is rapid and the products obtained are identical to those obtained by conventional synthetic methods.

RESULTS: The solubilities of the flame retardants decabromodiphenyl ether (deca‐BDE), antimony trioxide and high‐impact polystyrene (HIPS) in the ionic liquids, identified 1‐hexylpyridinium bromide as the most suitable for solid–liquid and liquid–liquid extraction, for the selective recovery of materials from the plastic composite. Optimum extraction of deca‐BDE and antimony trioxide was achieved by liquid–liquid extraction from an 8% solution of HIPS in ethyl acetate, with a reaction time of 10 min at 77 °C. The percentages of deca‐BDE and Sb2O3 extracted are 92.7% and 99.9%, respectively. The chain length of the polymer is not degraded by the extraction process, giving a residue that can be recycled.

CONCLUSIONS The results show that ionic liquids can be designed to achieve selective material recovery from composites. Copyright © 2008 Society of Chemical Industry
Preparation of Ag‐doped TiO2nanoparticles for photocatalytic degradation of acetamiprid in water
Authors: Cao Yongsong , Tan Huihua , Shi Tianyu , Tang Tao , Li Jianqiang
Published: February 2008

BACKGROUND:Surface modification by doping with metal ions and organic polymers has been proven to be an efficient route to improve the photocatalytic activity of TiO2. Pesticide photocatalysis has been conducted with fine TiO2particles suspended in an aqueous phase.

RESULTS:It has been found that the Ag dopant accelerates TiO2anatase to rutile transformation. At relatively low Ag concentrations (2–6%), anatase grain sizes decreased and specific surface areas of the TiO2powders increased. The presence of Ag in crystalline TiO2was found to increase the photocatalytic activity of TiO2in the photocatalytic degradation of acetamiprid at 25 °C.

CONCLUSION:All photocatalytic degradations of acetamiprid followed pseudo‐first‐order degradation kinetics (Ct=C0e−kt) and parameters like the concentration of doped Ag appeared to play an important role affecting the reaction rate. The photocatalytic degradation velocity constant (k) was found to increase quickly with the Ag content, increasing fromn= 0.02 to 0.06, and decreased slowly fromn= 0.08 to 0.12. The half‐lives of degradation (t1/2) were 18.8, 11.3, 16.2, 10.0, 6.9, 8.4 and 14.7 min atn= 0, 0.02, 0.04, 0.06, 0.08 and 0.12, respectively. The optimal mole percentage of Ag in TiO2should be between 4% and 8%. Copyright © 2008 Society of Chemical Industry
Integrated system for the biological solubilization and precipitation of heavy metals for the remediation of contaminated media
Authors: Cabrera Gema , Gómez Jose M , Cantero Domingo
Published: February 2008

BACKGROUND The work described here concerns a laboratory‐scale investigation into the remediation of sand artificially contaminated with a mixture of heavy metals using a two‐step process: the first step involved solubilization of the sand contaminants with sulfur‐oxidizing bacteria and the second step consisted of the precipitation of heavy metals from solution with sulfate‐reducing bacteria. Initially it was necessary to study the immobilization of sulfur‐oxidizing bacteria (Acidithiobacillus ferrooxidans and At. thiooxidans) on polyurethane foam. A support colonized by At. thiooxidans was selected and was added to a reactor for the continuous system. The acidic medium generated in this reactor was added to a column along with 50 g of artificially contaminated sand (85 mg Cr(III), 20 mg Ni(II) and 200 mg Zn(II)). The effluent from this step was collected in a reservoir tank and H2S, which was biologically generated by sulfate‐reducing bacteria (Desulfovibrio sp.), was added in order to carry out the precipitation of metals.

RESULTS: When 2.4 L of acid medium was passed through the column, it was observed that 14.6% of Cr(III), 26.7% of Ni(II) and 90.5% of Zn(II) were solubilized. The leachate (2.4 L) was treated with 2.2 L of reducing medium and 2.2% Cr(III), 54% Ni(II) and 28% Zn(II) of metals present in leachate were precipitated.

CONCLUSION: The proposed process is therefore suitable for the extraction and deposition of heavy metals from contaminated media and several design changes are currently being made in order to improve and optimize this remediation system. Copyright © 2008 Society of Chemical Industry
Biosorption potential of dried Penicillium restrictum for Reactive Orange 122: isotherm, kinetic and thermodynamic studies
Authors: Ilhan Semra , Iscen Cansu Filik , Caner Necmettin , Kiran Ismail
Published: February 2008

BACKGROUND: This paper evaluates the biosorption of Reactive Orange 122 dye (RO 122) by dried Penicillium restrictum cells. The aim was to determine the pH, contact time, temperature and dye concentration for the applicability of biomass as an alternative biosorbent for the removal of RO 122.

RESULTS: Optimum initial pH and equilibrium time for RO 122 were determined as 1.0 and 75 min at 25 °C, respectively. The maximum biosorption capacity (qmax) of biomass obtained from the Langmuir fit was 180.7, 190.1 and 219.8 mg g−1 biomass at 25, 40 and 50 °C, respectively. Both Langmuir and Freundlich isotherm models were fitted to the experimental data at constant temperatures of 25, 40 and 50 °C. The biosorption process was found to obey a pseudo‐second‐order kinetic model and was favourable at high temperatures.

CONCLUSIONS: The biomass could be an alternative biosorbent to RO 122 dye removal because of having advantages of being easily cultivable, its low cost, high biosorption capacity with low biomass dosage (0.4 g dm−3) and reasonably rapid biosorption rate. Copyright © 2008 Society of Chemical Industry