bluuebunny/crossref_metadata_2025 huggingface dataset:
Syntheses, Structures and Near‐IR Luminescent Studies on Ternary Lanthanide (ErIII, HoIII, YbIII, NdIII) Complexes Containing 4,4,5,5,6,6,6‐Heptafluoro‐1‐(2‐thienyl)hexane‐1,3‐dionate
Authors: Sun Li‐Ning , Yu Jiang‐Bo , Zheng Guo‐Li , Zhang Hong‐Jie , Meng Qing‐Guo , Peng Chun‐Yun , Fu Lian‐She , Liu Feng‐Yi , Yu Ying‐Ning
Published: August 2006

The ligand Hhfth [4,4,5,5,6,6,6‐heptafluoro‐1‐(2‐thienyl)hexane‐1,3‐dione], which contains a heptafluoropropyl group, has been used to synthesize several new ternary lanthanide complexes (Ln = Er, Ho, Yb, Nd) in which the synergistic ligand is 1,10‐phenanthroline (phen) or 2,2′‐bipyridine (bipy). The two series of complexes are [Ln(hfth)3phen] [abbreviated as (Ln)1, where Ln = Er, Ho, Yb] and [Ln(hfth)3bipy] [abbreviated as (Ln)2, where Ln = Er, Ho, Yb, Nd]. Members of the two series have been structurally characterized. The growth morphology, diffuse reflectance (DR) spectra, thermogravimetric analyses, and photophysical studies of these complexes are described in detail. After ligand‐mediated excitation of the complexes, they all show the characteristic near‐infrared (NIR) luminescence of the corresponding Ln3+ ions (Ln = Er, Ho, Yb, Nd). This is attributed to efficient energy transfer from the ligands to the central Ln3+ ions, i.e. an antenna effect. The heptafluorinated substituent in the main hfth sensitizer serves to reduce the degree of vibrational quenching. With these NIR‐luminescent lanthanide complexes, the luminescent spectral region from 1300 to 1600 nm, which is of particular interest for telecommunication applications, can be covered completely. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Tuned Helical Array of RhIII/IrIII Cp* Complexes with Polypyridyl Ligands
Authors: Singh Sanjay K. , Chandra Manish , Dubey Santosh K. , Pandey Daya S.
Published: August 2006

Reactions of the chloro‐bridged dimeric complexes [{(η5‐C5Me5)M(μ‐Cl)Cl}2] (M = Rh, Ir) with the polypyridyl ligands 2,3‐di(2‐pyridyl)pyrazine (dpp) and 2,4,6‐tri(2‐pyridyl)‐1,3,5‐triazine (tptz) in the presence of ammonium tetrafluoroborate gave the mononuclear complexes [(η5‐C5Me5)MCl(κ2‐dpp)]BF4 [M = Rh (1), Ir (2)] and [(η5‐C5Me5)MCl(κ2‐tptz)]BF4 [M = Rh (3), Ir (4)]. The complexes have been characterised by elemental analysis, FAB‐MS, ESMS, IR, NMR, electronic and emission spectroscopic studies and the molecular structures of 1, 2 and 3 have been crystallographically determined. Structural studies on the complexes revealed the presence of helical superstructures resulting from C–H···X (X = N, F, Cl and π) interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Organoethynylxenon(II) Tetrafluoroborates, [RC≡CXe][BF4] – The First Examples of Isolated Alkynylxenonium Salts: Preparation and Multi‐NMR Characterisation
Authors: Frohn Hermann‐Josef , Bardin Vadim V.
Published: August 2006

The perfluorinated organoethynylxenon(II) salts, [RC≡CXe][BF4] [R = CF3, C3F7, (CF3)2CF, cis‐, trans‐CF3CF=CF, C6F5], were prepared by the reaction of XeF2 with the corresponding perfluoroorganoethynyldifluoroboranes, RC≡CBF2, in 1,1,1,3,3‐pentafluoropropane (PFP) or CH2Cl2 at –60 to –40 °C and isolated in 30–98 % yield. Similarly, the non‐fluorinated organoethynylxenon(II) salts [C4H9C≡CXe][BF4] and [(CH3)3CC≡CXe][BF4] were obtained in 20 to 40 % yield. All [RC≡CXe][BF4] salts are soluble in anhydrous HF (aHF) and the salts with R = C4H9 or R = (CH3)3C display sufficient solubility in the weakly coordinating solvents CH2Cl2 and PFP. The xenonium salts [RC≡CXe][BF4] were unambiguously characterised by their 1H‐, 11B‐, 13C‐, 19F‐, and 129Xe NMR spectra in solution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Phosphavinylidene(oxo)phosphorane Mes*P(O)=C=PMes*: A Diphosphaallene Featuring λ5σ3‐ and λ3σ2‐Phosphorus Atoms
Authors: Septelean Raluca , Ranaivonjatovo Henri , Nemes Gabriela , Escudié Jean , Silaghi‐Dumitrescu Ioan , Gornitzka Heinz , Silaghi‐Dumitrescu Luminita , Massou Stéphane
Published: August 2006

Bis(2,4,6‐tri‐tert‐butylphenyl)phosphavinylidene(oxo)phosphorane (1) (Mes* = 2,4,6‐tri‐tert‐butylphenyl), the first 1λ5σ3,3λ3σ2‐diphosphaallene, has been synthesised by addition of the phosphaalkenyllithium Mes*P=C(Li)Cl to dichlorophosphane oxide Mes*P(O)Cl2. Compound 1 is stable in the solid‐state but undergoes a slow intramolecular cyclisation in solution by addition of a C–H bond of an ortho‐tert‐butyl group to the σ3‐P=C double bond. Water adds chemoselectively and regioselectively to the λ5σ3‐P=C bond, which appears to be more reactive than the λ3σ2‐P=C bond. This leads to the hydrolysis compound 8 which has been structurally characterised. The new bis(phosphane oxide)methylene 9 formed from the successive cyclisation of anortho‐tert‐butyl group to the λ5σ3‐P=C bond and addition of water to the λ3σ2‐P=C bond has also been structurally characterised. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Interactions of Insulin‐Mimetic Vanadium Complexes with the Cell Constituents ATP and Glutathione
Authors: Dörnyei Ágnes , Marcão Susana , Costa Pessoa João , Jakusch Tamás , Kiss Tamás
Published: August 2006

In order to assess the molecular form of vanadium insulin‐mimetic complexes in cells, the interactions of VIVO–maltolate and VIVO–dipicolinate systems with adenosine 5′‐triphosphate (ATP) and glutathione (GSH) in aqueous solution were studied by employing pH potentiometry, and EPR, CD and UV/Vis spectroscopy. The stoichiometries and stability constants of the complexes formed were determined at 25 °C with an ionic strength of I = 0.2 mol dm–3 (KCl). The most probable binding mode of the complexes formed in solution was determined by means of various spectral methods. The results suggest that from among the important cell constituents, GSH mostly takes part in the reduction of VV to VIV and helps keep VIV in this oxidation state. ATP, which is a strong VIVO binder, chelates the metal ion, forming binary and/or ternary complexes. The results of this work strongly suggest that ATP binds relevant VIVO species under cellular conditions and thus might somehow be involved in the insulin‐mimetic action of VIVO compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
First Example of a Gold(I) N‐Heterocyclic‐Carbene‐Based Initiator for the Bulk Ring‐Opening Polymerization of L‐Lactide
Authors: Ray Lipika , Katiyar Vimal , Raihan Mustafa J. , Nanavati Hemant , Shaikh Mobin M. , Ghosh Prasenjit
Published: August 2006

Synthesis, structure, and catalysis studies of two Au‐ and Ag‐based initiators, namely, [3‐(N‐tert‐butylacetamido)‐1‐(2‐hydroxycyclohexyl)imidazol‐2‐ylidene]AuCl (1c) and [3‐(N‐tert‐butylacetamido)‐1‐(2‐hydroxycyclohexyl)imidazol‐2‐ylidene]AgCl (1b), for the bulk ring‐opening polymerization of L‐lactide are reported. Specifically, gold complex 1c was obtained from silver complex 1b by the transmetalation reaction with (SMe2)AuCl. Silver complex 1b was synthesized by the treatment of 3‐(N‐tert‐butylacetamido)‐1‐(2‐hydroxycyclohexyl)imidazolium chloride (1a) with Ag2O. Compound 1a was synthesized directly from the reaction of N‐tert‐butyl‐2‐chloroacetamide, cyclohexene oxide, and imidazole. The molecular structures of 1a, 1b, and 1c have been determined by X‐ray diffraction studies. The formation of neutral monomeric complexes with linear geometries at the metal centers was observed for both 1b and 1c. The Au and Ag complexes 1c and 1b successfully catalyzed the bulk ring‐opening polymerization of L‐lactide at elevated temperatures under solvent‐free melt conditions to produce moderate to low molecular weight polylactide polymers with narrow molecular weight distributions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Comparative Study of the Optical and Electroluminescent Properties of EuIII Complexes with TTA and 2‐(2′‐Pyridyl)azoles: The Crystal Structure of [Eu(TTA)3(PBO)]
Authors: Gao Li‐Hua , Guan Min , Wang Ke‐Zhi , Jin Lin‐Pei , Huang Chun‐Hui
Published: August 2006

Two EuIII mixed‐ligand complexes, namely [Eu(TTA)3(PBO)]and [Eu(TTA)3(PBT)] [TTA = 1,1,1‐trifluoro‐3‐(2‐thenoyl)acetonato, PBO = 2‐(2′‐pyridyl)‐1,3‐benzoxazole, and PBT = 2‐(2′‐pyridyl)‐1,3‐benzothiazole], have been synthesized. [Eu(TTA)3(PBO)] has been structurally characterized by single‐crystal X‐ray diffraction analysis. The complex crystallizes in the monoclinic space group C2/c. The lattice parameters are a = 41.346(4), b = 10.0538(8), c = 20.3793(16) Å, β = 110.922(2)°, Z = 8. The EuIII ion is eight‐coordinate, with three bidentate TTA– anions and one bidentate N,O‐chelated PBO molecule. A comparative study by UV and emission spectroscopy was carried out and electroluminescent properties of the related complexes [Eu(TTA)3(PBO)] and [Eu(TTA)3(PBT)] are reported as well. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Luminescent Cyclometalated Iridium(III) Polypyridine Complexes Containing a Thiourea Moiety: Synthesis, Characterization, Photophysics, Electrochemistry and Anion‐Binding Properties
Authors: Lo Kenneth Kam‐Wing , Lau Jason Shing‐Yip , Lo David Ka‐Kit , Lo Larry Tso‐Lun
Published: August 2006

A series of new luminescent cyclometalated iridium(III) polypyridine thiourea complexes [Ir(N‐C)2(N‐N)](PF6) [HN‐C =2‐phenylpyridine (Hppy), N‐N = N‐ethyl‐N′‐1,10‐phenanthrolin‐5‐yl thiourea (phen‐TU‐Et) (1a), N‐phenyl‐N′‐1,10‐phenanthrolin‐5‐yl thiourea (phen‐TU‐Ph) (1b), N‐(1‐adamantanemethyl)‐N′‐1,10‐phenanthrolin‐5‐yl thiourea (phen‐TU‐MeA) (1c); HN‐C = 7,8‐benzoquinoline (Hbzq), N‐N = phen‐TU‐Et (2a), phen‐TU‐Ph (2b), phen‐TU‐MeA (2c); HN‐C = 2‐phenylquinoline (Hpq), N‐N = phen‐TU‐Et (3a), phen‐TU‐Ph (3b), phen‐TU‐MeA (3c)] have been synthesized and characterized. The photophysical and electrochemical properties of these complexes have been investigated. On the basis of the photophysical and electrochemical data, the nature of the emissive states has been assigned. The thiourea moieties of the complexes allow them to act as receptors for anions; the binding of OAc–, F–, and H2PO4– to the complexes has been investigated by emission titrations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis and Reactivity of New Mono‐ and Dinuclear Hydridoirida‐β‐diketones – The Formation and Characterization of a Dinuclear Tris‐μ‐acyliridium(III) Complex
Authors: Acha Francisco , Garralda María A. , Hernández Ricardo , Ibarlucea Lourdes , Pinilla Elena , Torres M. Rosario , Zarandona Malkoa
Published: August 2006

The hydridoirida‐β‐diketone [IrH{[PPh2(o‐C6H4CO)]2H}Cl] (1) reacts with silver salts of potentially coordinating anions such as tosylate (–OTs) or triflate (–OTf) to afford the mononuclear neutral derivatives [IrH{[PPh2(o‐C6H4CO)]2H}(X)] [X = OTs (2), OTf (3)]. In acetone solution the triflate anion in 3 is displaced by the solvent to afford the cationic complex [IrH{[PPh2(o‐C6H4CO)]2H}(acetone)]OTf (4), which is stable only in acetone solution. The reaction of 1 with halide scavengers containing less coordinating anions such as PF6– or BF4– results in the formation of cationic compounds [{IrH[{PPh2(o‐C6H4CO)}2H]}2(μ‐Cl)]A [A = BF4 (5), PF6 (6)] containing a dinuclear species with a single chlorine atom bridging two hydridoirida‐β‐diketone fragments. Both fragments are magnetically non‐equivalent and the acylphosphane groups in each hydridoirida‐β‐diketone fragment are chemically equivalent. This species undergoes a fluxional process in solution, with ΔH‡ = 7.8 ± 0.4 kcal mol–1 and ΔS‡ = –10.9 ± 0.5 eu. A combination of rotation around the Ir–Cl bonds and variation of the Ir–Cl–Ir angle is suggested to be responsible for the fluxionality. Complex 5 reacts further with AgBF4 to undergo chloride abstraction along with hydrogen loss and deprotonation to give the cationic dinuclear complex [Ir2H{PPh2(o‐C6H4CO)}{μ‐PPh2(o‐C6H4CO)}3]BF4 (7), which contains an acylphosphane chelate along with three acylphosphane bridging ligands and a single hydrido ligand. Bubbling of HCl through an MeOH solution of 7 gives 1, thus making the loss of hydride, enolic protons and chloride from complex 1 a reversible process. All the complexes were fully characterized spectroscopically. Single‐crystal X‐ray diffraction analysis was performed on complexes 5 and 7. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Identification of the Dinuclear and Tetranuclear Air‐Oxidized Products Derived from Labile Phenolate‐Bridged Dimanganese(II) Pyridyl‐Chelate Compounds
Authors: Larsen Frank Bartnik , Boisen Astrid , Berry Kevin J. , Moubaraki Boujemaa , Murray Keith S. , McKee Vickie , Scarrow Robert C. , McKenzie Christine J.
Published: August 2006

Dioxygen‐sensitive dinuclear manganese complexes of the phenoxo‐hinged dinucleating ligand 2,6‐bis{[N,N′‐bis(2‐picolyl)amino]methyl}‐4‐tert‐butylphenolato (bpbp–) containing exogenous labile THF, water and perchlorato ligands are described. The manganese(II) complexes [Mn2(bpbp)(ClO4)2(THF)]+ (1) and [Mn2(bpbp)(ClO4)(H2O)2]2+ (2) have been isolated as the salts 1·ClO4·THF·3H2O, 1·B(C6H5)4·4THF and 2·(ClO4)2·H2O. Complexes 1 and 2 are spontaneously oxidised in air in solution and the solid state. The reaction products of the air oxidation in THF, water and methanol solutions are labile dinuclear MnII–MnIII, MnIII2 and MnIII–MnIV complexes containing water‐ and methanol‐derived exogenous ligands. In addition, a Mn4 complex has been isolated. Magnetic susceptibility data confirm the MnII–MnIII oxidation state assignment with an S = 2/S = 5/2 model with weak antiferromagnetic coupling (J = –3.7 cm–1) in [Mn2(bpbp)(CH3O)2(H2O)2](ClO4)2 [3·(ClO4)2]. A tetranuclear complex, [Mn4(O)4–n(OH)n(bpbp)2](ClO4)4 [n = 1 or 2; 7·(ClO4)4], recovered from THF shows a Mn4O6 adamantane‐type core with the O bridges furnished by the two phenolato groups and four hydroxide/oxide bridges. We have arrived at two feasible formulations for the core metal oxidation states and oxo‐bridge protonation states, namely [MnIII4(O)2(OH)2(bpbp)2]4+ and [MnIII3MnIV(O)3(OH)(bpbp)2]4+, for 7, on the basis of a bond valence sum analysis of the crystal structure, elemental analysis and XANES. Thus, complex 7 is at least two oxidation state levels lower than known complexes with the Mn4O6 adamantane core structure. The magnetism of 7 was fitted well to an MnIII4 three‐J model. Complex cations related to 3 by homology, and to 7 by hydration/solvation, have been identified by ESI mass spectrometry. The [Mn2(bpbp)(OH)2(H2O)2]2+ ion (4) present in aqueous solutions on dissolution of 1·ClO4·THF·3H2O in air or by simple dissolution of 3 in water‐containing solvent is isoelectronic to 3. In the presence of significant amounts of water the MnII–MnIII complexes 3 and 4 are susceptible to further metal oxidation and concomitant aquo ligand deprotonation to give ions assignable to [MnIII/IV2(bpbp)O(OCH3)2(H2O)]2+ (5) and [MnIII2(bpbp)(OH)3(H2O)]2+ (6). ESI mass spectra of water or methanol solutions of 1, 2, 3 and 7 show predominantly an ion assignable to the oxide [Mn2(bpbp)(O)]2+ (8). Cation 8 is most likely not present in solution. Using mild source conditions and MS‐MS techniques, the gas‐phase fragmentation pathways to generate 8 have been mapped. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Pressure Effect Investigations on the Spin Crossover Systems{Fe[H2B(pz)2]2(bipy)} and {Fe[H2B(pz)2]2(phen)}
Authors: Galet Ana , Gaspar Ana Belén , Agusti Gloria , Muñoz M. Carmen , Levchenko Georgii , Real José Antonio
Published: August 2006

Pressure effect studies on the spin crossover behaviour of the mononuclear compounds {Fe[H2B(pz)2]2(bipy)}(1) and {Fe[H2B(pz)2]2(phen)}(2) have been performed in the range of 105 Pa–1.02 GPa at variable temperatures (100–310 K). Continuous spin transitions and displacement of its characteristic temperature has been observed for 1 with increasing pressure. Meanwhile the response of 2 under applied pressures is quite unexpected, and can only be understood in terms of a crystallographic phase transition or change in the bulk modulus of the compound. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Studies on the Interaction of Vanadia with Modified Silica Supports and Catalytic Activity for Oxidative Dehydrogenation of Propane: Effect of Support Modification by Al3+, Zr4+ or Y3+
Authors: Sasikala Rajamma , Sudarsan Vasanth , Kulshreshtha Shailendra K.
Published: August 2006

Detailed structural studies of vanadia supported on SiO2 and modified SiO2 (Si0.8M0.2O2±δ where M = Al3+, Zr4+ and Y3+) were carried out using different techniques such as powder XRD, IR spectroscopy and 29Si, 27Al and 51V MAS NMR spectroscopy. All samples except vanadia impregnated on Zr4+ or Y3+ modified SiO2 existed as amorphous phases. A crystalline phase of ZrO2 was seen in Zr4+ modified SiO2 and YVO4 was seen in Y3+ modified SiO2 after vanadia impregnation. Based on 29Si MAS NMR and IR spectroscopic studies it was concluded that substitution of Si4+ by M results in the breakage of the Si–O–Si network and formation of silicon structural units with Si–O–M type linkages. Unlike all other modified SiO2, the silicon structural units remained unaffected in Al3+ modified SiO2 before and after vanadia impregnation. A profound change in the interaction of vanadia with the support was observed when the SiO2 support was modified with different cations and in all cases the V5+ preferentially interacted with the substituted cations. Two types of vanadia species, viz. the octahedral and tetrahedral V5+, were present in vanadia impregnated silica and Al3+ modified silica but the amount of tetrahedral V5+ was more in the latter. In Zr4+ modified silica, V5+ was present in a crystalline environment which is the V5+ dissolved in the ZrO2 phase. Vanadia impregnated on Y3+ modified silica exhibited very little chemical shift anisotropy indicating a symmetric environment around V5+ in YVO4. The catalytic activity for the selective oxidation of propane to propene was tested on these supported catalysts. Vanadia supported on Zr4+ modified silica showed maximum selectivity whereas vanadia on silica and Al3+ modified silica showed comparable selectivity for propene formation. Vanadia on Y3+ modified silica did not show the formation of propene at all. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Testing Phosphanes in the Palladium Catalysed Allylation of Secondary and Primary Amines
Authors: Thoumazet Claire , Grützmacher Hansjörg , Deschamps Bernard , Ricard Louis , le Floch Pascal
Published: August 2006

The electronic nature of the ligand plays a crucial role in the palladium‐catalysed allylation of amines with allylic alcohols. The better the ligand is as a π acceptor, the more active the catalyst. Experiments with a series with mono‐ and bidentate ligands featuring phosphanes and phospholes applied in the catalytic allylation of aniline clearly demonstrate this. Bolstered by DFT calculations, we have devised a new efficient catalyst for this process which carries the strong π acceptor 1,2,5‐triphenylphosphole as a ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Claisen Rearrangement of Carbohydrate‐Derived Precursors Towards Highly Functionalized Cyclooctenones with L‐xylo, D‐arabino and L‐lyxo Configuration and Their Diastereoselective Transformations
Authors: Jürs Stefan , Werschkun Barbara , Thiem Joachim
Published: August 2006

D‐Glucose and D‐mannose have been transformed into precursors incorporating allyl vinyl ether substructures. Both thermally and catalytically, these cyclic allyl vinyl ethers could be converted into the corresponding Claisen rearrangement products. The conformations of these enantiopure 5‐cyclooctenones were studied by NMR spectroscopy and X‐ray crystallography. They proved to be versatile substrates for highly stereo‐ and regioselective modifications. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis of Conformationally Locked Carbocyclic Nucleosides Built on a Thiabicyclo[3.1.0]hexane System as a Pseudosugar Surrogate
Authors: Elhalem Eleonora , Comin María J. , Rodriguez Juan B.
Published: August 2006

The synthesis of prototype models of purine and pyrimidine carbanucleosides built on a 6‐thiabicyclo[3.1.0]hexane system as pseudosugar moiety has been investigated. These pyrimidine carbanucleosides proved to be very stable compounds, in contrast to the parent epoxy analogs, which experienced epoxide ring‐opening due to intramolecular enol base attack. In addition, as the synthesis of a thiirane moiety fused to a five‐membered ring is not a trivial synthetic task, validation and optimization of the existing methods for episulfide preparation were required to access the committed synthetic precursor of the title compounds: (±)‐(1RS,2RS,5SR)‐6‐thiabicyclo[3.1.0]hexan‐2‐ol, compound 28. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
On extrinsic information of good binary codes operating over Gaussian channels
Authors: Peleg M. , Sanderovich A. , Shamai (Shitz) S.
Published: August 2006

We show that the extrinsic information about the coded bits of any good (capacity achieving) binary code operating over a Gaussian channel is zero when the channel capacity is lower than the code rate and unity when capacity exceeds the code rate, that is, the extrinsic information transfer (EXIT) chart is a step function of the signal to noise ratio and independent of the code. It follows that, for a common class of iterative receivers where the error correcting decoder must operate at first iteration at rate above capacity (such as in turbo equalization, iterative channel estimation, parallel and serial concatenated coding and the like), classical good codes which achieve capacity over the Additive White Gaussian Noise Channel are not effective and should be replaced by different new ones. Copyright © 2006 AEIT.
Performance of collaborative codes in CSMA/CD environment
Authors: Gebali F. , Al‐Sammak A. J.
Published: August 2006

A new medium access control scheme is proposed for implementing collaborative codes in a system using carrier sense multiple access with collision detection protocol (CC‐CSMA/CD). We also propose a new backoff algorithm which is simple to implement and to analyse. A discrete‐time Markov chain analytical model is developed for CC‐CSMA/CD. The resulting model describes the regular CSMA/CD as a special case. Protocol performance measures were studied such as throughput, packet acceptance probability, average packet delay and channel utilisation. It is found that CC‐CSMA/CD offers improvements over a system that uses CSMA/CD in terms of throughput, packet acceptance probability, delay and channel utilisation. Copyright © 2006 AEIT.
Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives
Authors: Zhonghe Zhou
Published: August 2006

The Jehol Biota, preserved in the lacustrine sediments of Liaoning Province, northeast China, has provided a new window for understanding Early Cretaceous terrestrial ecosystems. Based on recent geochronological and biostratigraphic studies of the fossil‐bearing deposits, a preliminary temporal framework has been established and suggests that the Jehol Biota had lasted for at least 11 Ma during the late Early Cretaceous (131–120 Ma). The development of the Jehol Biota can be divided into three major phases, with the most significant biological radiations occurring in the second phase between the Barremian and Aptian (approximately 125 Ma). Thanks to a diverse forest environment, major vertebrate groups, i.e. pterosaurs, dinosaurs, birds and mammals, in the Jehol Biota are characterized by a remarkably high percentage of arboreal and herbivorous forms. In addition to strong phylogenetic and morphological differentiation and high taxonomic diversity, the Jehol Biota is also characterized by significant dietary differentiation and biological interactions, i.e. competition and co‐evolution between various animal groups, in an environment shaped by tectonic activities and palaeoclimatic changes both at a global and local scale. Copyright © 2006 John Wiley & Sons, Ltd.
Distinguishing anomalocaridids from arthropods and priapulids
Authors: Xianguang Hou , Bergström Jan , Jie Yang
Published: August 2006

The Chengjiang fossil lagerstätte has yielded four described species of dinocaridids. These have been interpreted either as arthropods or as arthropod progenitors, occasionally with the anomalocaridid Parapeytoia yunnanensis serving as a link. This view is rejected both because anomalocaridids have a number of derived characters absent from early arthropods, and also because a shared origin gives a more parsimonious picture. Sclerites thought to belong to the mouth of P. yunnanensis differ fundamentally from those of its holotype and from those of other dinocaridids. It appears that they belong to a new large priapulid, described here as Omnidens amplus gen. et sp. nov. Copyright © 2006 John Wiley & Sons, Ltd.
Use of tight belts and risk of esophageal adenocarcinoma
Authors: Lagergren Jesper , Jansson Catarina
Published: August 2006

It has recently been hypothesized that the general shift in use from suspenders to belts among men might be a factor that could promote reflux, particularly among overweight men, and thereby contribute to the alarmingly increasing incidence of esophageal and cardia adenocarcinoma. We addressed this hypothesis in a nationwide Swedish population‐based case–control study, conducted in 1995–1997. Included were 189 patients with esophageal adenocarcinoma and 262 patients with cardia adenocarcinoma, who were compared with 167 patients with esophageal squamous cell carcinoma and 820 population‐based control participants. Data were collected at structured face‐to‐face interviews with all study participants. Tumor classification was uniform and thorough. Odds ratios (OR) with 95% confidence intervals (CI), adjusted for potential confounders, were estimated in multivariable logistic regression models. Daily use of tight belts 20 years earlier did not entail an increased risk of adenocarcinoma of the esophagus (OR 1.1, 95% CI 0.7–1.8) or cardia (OR 0.8, 95% CI 0.5–1.3) compared to never use. Adjustment for reflux symptoms, body mass and other potentially relevant covariates did not influence the results. Similarly, in analyses restricted to overweight men, no associations were identified. No association with esophageal squamous cell carcinoma was found. In conclusion, this study provided no support for the hypothesis that use of tight belts is associated with an increased risk of developing esophageal or cardia adenocarcinoma. © 2006 Wiley‐Liss, Inc.
Prospective study of vegetable consumption and liver cancer in Japan
Authors: Pham Truong‐Minh , Fujino Yoshihisa , Ide Reiko , Kubo Tatsuhiko , Shirane Kiyoyumi , Tokui Noritaka , Mizoue Tetsuya , Ogimoto Itsuro , Matsuda Shinya , Yoshimura Takesumi
Published: August 2006

We examined the relationship between vegetable consumption and the risk of death from liver cancer in a cohort study in Japan. This analysis is based on data from 6,049 subjects aged 40 to 79 years enrolled in a cohort study conducted in Fukuoka Prefecture, Japan. The follow‐up period was from 1986 to 1999. All liver cancer deaths were recorded. The vegetable consumption was classified into 3 groups: “once per week or less,” “2–4 times per week” and “daily intake.” The Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence interval (95% CI). A total of 51 male and 22 female liver cancer deaths were recorded during 62,343 person‐years of follow‐up. The “once per week or less” group was considered the referent group. In males, the multivariate HRs of liver cancer deaths were 0.61 (95% CI: 0.33–1.14) and 0.25 (95% CI: 0.11–0.59) in the “2–4 times per week” and “daily intake” groups, respectively. In females, the multivariate HRs were 0.44 (95% CI: 0.13–1.51) and 0.51 (95% CI: 0.16–1.69), respectively. The multivariate HRs were also reported by history of hepatitis and cirrhosis. In those without a history of these conditions, the multivariate HRs were 0.54 (95% CI: 0.27–1.09) and 0.36 (95% CI: 0.16–0.83). In those with a history of these conditions, the multivariate HRs were 0.58 (95% CI: 0.22–1.56) and 0.37 (95% CI: 0.13–1.06), respectively. Our study reveals an inverse association between vegetable consumption and the risk of death from liver cancer. These results provide further evidence of the protective effect of vegetables against liver cancer. © 2006 Wiley‐Liss, Inc.
Physical activity and lung cancer risk in the European Prospective Investigation into Cancer and Nutrition Cohort
Authors: Steindorf Karen , Friedenreich Christine , Linseisen Jakob , Rohrmann Sabine , Rundle Andrew , Veglia Fabrizio , Vineis Paolo , Johnsen Nina Fønns , Tjønneland Anne , Overvad Kim , Raaschou‐Nielsen Ole , Clavel‐Chapelon Françoise , Boutron‐Ruault Marie‐Christine , Schulz Mandy , Boeing Heiner , Trichopoulou Antonia , Kalapothaki Victoria , Koliva Maria , Krogh Vittorio , Palli Domenico , Tumino Rosario , Panico Salvatore , Monninkhof Evelyn , Peeters Petra H. , Boshuizen Hendriek C. , Bueno‐de‐Mesquita H. Bas , Chirlaque Maria‐Dolores , Agudo Antonio , Larrañaga Nerea , Quirós José R. , Martínez Carmen , Barricarte Aurelio , Janzon Lars , Berglund Göran , Bingham Sheila , Khaw Kay‐Tee , Key Timothy J. , Norat Teresa , Jenab Mazda , Cust Anne , Riboli Elio
Published: August 2006

Research conducted predominantly in male populations on physical activity and lung cancer has yielded inconsistent results. We examined this relationship among 416,277 men and women from the European Prospective Investigation into Cancer and Nutrition (EPIC). Detailed information on recent recreational, household and occupational physical activity, smoking habits and diet was assessed at baseline between 1992 and 2000. Relative risks (RR) were estimated using Cox regression. During 6.3 years of follow‐up we identified 607 men and 476 women with incident lung cancer. We did not observe an inverse association between recent occupational, recreational or household physical activity and lung cancer risk in either males or females. However, we found some reduction in lung cancer risk associated with sports in males (adjusted RR = 0.71; 95% confidence interval 0.50–0.98; highest tertile vs. inactive group), cycling (RR = 0.73; 0.54–0.99) in females and non‐occupational vigorous physical activity. For occupational physical activity, lung cancer risk was increased for unemployed men (adjusted RR = 1.57; 1.20–2.05) and men with standing occupations (RR = 1.35; 1.02–1.79) compared with sitting professions. There was no evidence of heterogeneity of physical activity associations across countries, or across any of the considered cofactors. For some histologic subtypes suggestive sex‐specific reductions, limited by subgroup sizes, were observed, especially with vigorous physical activity. In total, our study shows no consistent protective associations of physical activity with lung cancer risk. It can be assumed that the elevated risks found for occupational physical activity are not produced mechanistically by physical activity itself but rather reflect exposure to occupation‐related lung cancer risk factors. © 2006 Wiley‐Liss, Inc.
Raf kinases: Oncogenesis and drug discovery
Authors: Schreck Ralf , Rapp Ulf R.
Published: August 2006

Raf kinase signaling has been thoroughly investigated over the last 20 years. A‐Raf, B‐Raf and C‐Raf, the 3 mammalian members of the Raf family, are involved in a variety of cellular processes such as growth, proliferation, survival, differentiation and transformation. The detection of B‐RAF mutations in a wide variety of human cancers, the description of wildtype and mutant B‐RAF as tumor antigens in melanoma and the promising outcome of clinical trials evaluating the Raf inhibitor Nexavar® (Sorafenib, BAY 43‐9006) have sparked a broad interest in the scientific community. After a short historical detour and an introduction into Raf kinase signaling, we are going to discuss here recent outcomes of Raf kinase research with respect to tumor formation and give an overview on current efforts to develop anticancer therapies interfering with aberrant Raf kinase signaling. © 2006 Wiley‐Liss, Inc.
Aurora‐A induces cell survival and chemoresistance by activation of Akt through a p53‐dependent manner in ovarian cancer cells
Authors: Yang Hua , He Lili , Kruk Patricia , Nicosia Santo V. , Cheng Jin Q.
Published: August 2006

Aurora‐A is frequently altered in epithelial malignancies. Overexpressing Aurora‐A induces centrosome amplification and G2/M cell cycle progression. We have previously shown elevated level of Aurora‐A in ovarian cancer and activation of telomerase by Aurora‐A in human mammary and ovarian epithelia. Here we report that Aurora‐A protects ovarian cancer cells from apoptosis induced by chemotherapeutic agent and activates Akt pathway in a p53‐dependent manner. Ectopic expression of Aurora‐A renders cells resistant to cisplatin (CDDP), etoposide and paclitaxel‐induced apoptosis and stimulates Akt1 and Akt2 activity in wild‐type p53 but not p53‐null ovarian cancer cells. Aurora‐A inhibits cytochrome C release and Bax conformational change induced by CDDP. Knockdown of Aurora‐A by RNAi sensitizes cells to CDDP‐induced apoptosis and decreases phospho‐Akt level in wild‐type p53 cells. Reintroduction of p53 decreases Akt1 and Akt2 activation and restores CDDP sensitivity in p53‐null but not p53‐null‐Aurora‐A cells. Inhibition of Akt by small molecule inhibitor, API‐2, overcomes the effects of Aurora‐A‐on cell survival and Bax mitochondrial translocation. Taken collectively, these data indicate that Aurora‐A activates Akt and induces chemoresistance in a p53‐dependent manner and that inhibition of Akt may be an effective means of overcoming Aurora‐A‐associated chemoresistance in ovarian cancer cells expressing wild‐type p53. © 2006 Wiley‐Liss, Inc.
Tobacco smoke and bladder cancer—in the European prospective investigation into cancer and nutrition
Authors: Bjerregaard Bine Kjøller , Raaschou‐Nielsen Ole , Sørensen Mette , Frederiksen Kirsten , Christensen Jane , Tjønneland Anne , Overvad Kim , Chapelon Francoise Clavel , Nagel Gabriele , Chang‐Claude Jenny , Bergmann Manuela M. , Boeing Heiner , Trichopoulos Dimitrios , Trichopoulou Antonia , Oikonomou Eleni , Berrino Franco , Palli Domenico , Tumino Rosario , Vineis Paolo , Panico Salvatore , Peeters Petra HM , Bueno‐de‐Mesquita H. Bas , Kiemeney Lambertus , Gram Inger Torhild , Braaten Tonje , Lund Eiliv , Gonzalez Carlos A. , Berglund Göran , Allen Naomi , Roddam Andrew , Bingham Sheila , Riboli Elio
Published: August 2006

The purpose of the present study was to investigate the association between smoking and the development of bladder cancer. The study population consisted of 429,906 persons participating in the European Prospective Investigation into Cancer and Nutrition (EPIC), 633 of whom developed bladder cancer during the follow‐up period. An increased risk of bladder cancer was found for both current‐ (incidence rate ratio 3.96, 95% confidence interval: 3.07–5.09) and ex‐ (2.25, 1.74–2.91) smokers, compared to never‐smokers. A positive association with intensity (per 5 cigarettes) was found among current‐smokers (1.18, 1.09–1.28). Associations (per 5 years) were observed for duration (1.14, 1.08–1.21), later age at start (0.75, 0.66–0.85) and longer time since quitting (0.92, 0.86–0.98). Exposure to environmental tobacco smoke (ETS) during childhood increased the risk of bladder cancer (1.38, 1.00–1.90), whereas for ETS exposure as adult no effect was detected. The present study confirms the strong association between smoking and bladder cancer. The indication of a higher risk of bladder cancer for those who start smoking at a young age and for those exposed to ETS during childhood adds to the body of evidence suggesting that children are more sensitive to carcinogens than adults. © 2006 Wiley‐Liss, Inc.
Reproductive factors, exogenous hormone use and bladder cancer risk in a prospective study
Authors: Cantwell Marie M. , Lacey James V. , Schairer Catherine , Schatzkin Arthur , Michaud Dominique S.
Published: August 2006

Sex is a consistent predictor of bladder cancer: men experience 2–4‐fold higher age‐adjusted rates than women in the U.S. and Europe. The objective of this study was to examine whether hormone‐related factors are associated with bladder cancer in women. We examined parity, age at menarche, age at first birth, age at menopause, oral contraceptive use and menopausal hormone therapy (HT) use and bladder cancer risk in the Breast Cancer Detection Demonstration Project Follow‐Up Study. Endpoint and exposure information was collected on 54,308 women, using annual telephone interviews (1980–86) and 3 mailed, self‐administered questionnaires (1987–98). During an average follow‐up time of 15.3 years, 167 cases of bladder cancer were identified. Univariate and adjusted rate ratios (RRs) were estimated using Poisson regression. Parity, age at menarche, age at first birth, age at menopause, and oral contraceptive use were not associated with bladder cancer risk. The majority of menopausal women who took HT used estrogen therapy (ET). Postmenopausal women with less than 4 years, 4–9 years, 10–19 years and 20 or more years of ET use had RRs of 1.55 (95% CI = 0.96–2.51), 1.00 (95% CI = 0.49–2.04), 1.23 (95% CI = 0.62–2.43) and 0.57 (95% CI = 0.14–2.34), respectively, compared with nonusers (p = 0.50). Findings from this study are not consistent with the hypothesis that hormone‐related factors in women are associated with bladder cancer. © 2006 Wiley‐Liss, Inc.
Serum concentrations of estrogens, sex hormone‐binding globulin, and androgens and risk of breast cancer in postmenopausal women
Authors: Adly Laila , Hill Deirdre , Sherman Mark E. , Sturgeon Susan R. , Fears Thomas , Mies Carolyn , Ziegler Regina G. , Hoover Robert N. , Schairer Catherine
Published: August 2006

We assessed the relationship between serum concentrations of estrogens, androgens, and sex hormone‐binding globulin and risk of breast cancer among postmenopausal women. Study participants provided serum prior to breast biopsy or mastectomy in 3 hospitals in Grand Rapids, Michigan between 1977 and 1987. A total of 179 subjects with localized breast cancer were compared to 152 subjects with nonproliferative breast changes that have not been associated with elevated breast cancer risk. Increasing serum concentrations of estrone and estrone sulfate were associated with increases in breast cancer risk; the odds ratios (ORs) in the fourth quartiles compared to the first were 2.3 (95% confidence interval (CI) 1.1–4.6) for both (p‐trend = 0.02 and 0.03, respectively). Estradiol and bioavailable estradiol concentrations were associated with nonstatistically significant increases in risk. Androstenediol levels were associated with risk (p‐trend = 0.01); the OR in the fourth compared to the first quartile was 2.2 (95% CI 1.0–4.6). Testosterone, dehydroepiandrosterone and androstenedione levels were not associated with increased risk. Sex hormone‐binding globulin was associated with a nonsignificant decrease in risk. Associations with estrone and estrone sulfate persisted after adjustment for androstenediol (ORs for fourth compared to first quartiles were 2.0 (95% CI 0.9–4.5) and 2.2 (95% CI 1.0–4.6), respectively (p‐trend = 0.16 for both). The association with androstenediol was attenuated after adjustment for estrone (OR for fourth compared to first quartile was 1.6 (95% CI 0.7–3.6); p‐trend = 0.13). Higher serum concentrations of estrogens were associated with increased breast cancer risk in postmenopausal women. Androgen levels were not independently associated with substantially increased risk. © 2006 Wiley‐Liss, Inc.
Working in partnership: Skills transfer in developing a cross‐cultural research team
Authors: Guthrie Jill , Dance Phyll , Cubillo Carmen , McDonald David , Tongs Julie , Brideson Tom , Bammer Gabriele
Published: August 2006

As part of a broader study on Indigenous illegal drug use, the authors undertook skills training to increase cross‐cultural mutual understanding of the often different approaches and methodologies between research and practice, as well as Aboriginal and non‐Aboriginal understandings of these approaches. The study and the skills transfer training were part of a longerterm partnership between Winnunga Nimmityjah Aboriginal Health Service and the National Centre for Epidemiology and Population Health at The Australian National University, Canberra, Australia. The authors describe the skills transfer process involving specific training in the ethical issues relating to research generally and this particular study, research funding processes, basic epidemiological and biostatistical concepts, and aspects of interviewing and questionnaire design. They use five vignettes to illustrate how the skills transfer process fulfilled their broader aim related to the ethical conduct of research with Aboriginal and Torres Strait Islander communities. © 2006 Wiley Periodicals, Inc.
Burnout among volunteers in the social services: The impact of gender and employment status
Authors: Kulik Liat
Published: August 2006

This study examines whether gender and employment status affect burnout, motives for volunteering, and difficulties associated with volunteer activity in social and community services in Israel. The sample included 375 men and women aged 16 through 80. Participants were divided into four groups by employment status: high school students, employed persons, retirees, and unemployed persons. The findings revealed that employment status had a more significant impact on the research variables than did gender. Burnout correlated positively with difficulty in relations with beneficiaries among men, and with difficulty in relations with the provider organization among women. Female students and unemployed men were found to be particularly vulnerable to burnout. © 2006 Wiley Periodicals, Inc.
Young Jamaicans' attitudes toward mental illness: Experimental and demographic factors associated with social distance and stigmatizing opinions
Authors: Jackson Dahra , Heatherington Laurie
Published: August 2006

Two large‐scale studies assessed the nature and correlates of young Jamaicans' attitudes toward mental illness. In study 1, students viewed a videotaped job interview for a teacher whose history was manipulated to include a history of mental illness, or not. Students desired significantly less social distance (i.e., more contact) with the “normal” confederate, followed by those with a mental illness history. The putative cause of the mental illness (biomedical vs. psychosocial) made no difference. Study 2, a survey study, revealed the presence of negative attitudes toward people with mental illness and several demographic (age, gender, social class, and rural vs. urban location) differences. Implications of the results for community public health, education, and stigma‐reduction programs, as well as a comparison with research on stigma and attitudes toward mental illness in American culture, are discussed. © 2006 Wiley Periodicals, Inc.
Stress among black women in a South African township: The protective role of religion
Authors: Copeland‐Linder Nikeea
Published: August 2006

Communities that have been exposed to high levels of stress and where religiosity is salient are ideal contexts in which to examine the role of religion in stress processes. The present study examines the protective function of religiosity among Black women in a South African township. The women ( N = 172) were interviewed about sources of stress, religiosity, depressive symptomatology, and physical health problems. The results revealed that engagement in formal religion buffered the aggregate effects of multiple stressors (cumulative stress), as well as the effects of work stress and experiencing racism on physical health. Prayer also buffered the effects of work stress on physical health and reduced the deleterious effects of work stress and experiencing racism on depressive symptomatology. © 2006 Wiley Periodicals, Inc.
The effects of prospective naturalistic contact on the stigma of mental illness
Authors: Couture Shannon M. , Penn David L.
Published: August 2006

The primary aim of this study was to determine whether naturalistic, interpersonal contact with persons with a severe mental illness (SMI) could reduce stigma. Participants from the agency Compeer (which pairs volunteers with people with SMI) were compared to volunteers from a control agency and to nonvolunteer participants from the community on stigma measures over a 6‐month period. The quality of the relationship between the Compeer volunteer and consumer and its association with changes in stigmatizing attitudes was also assessed. The results provide preliminary evidence that naturalistic contact can reduce negative affective responses to individuals with SMI. Furthermore, changes in affective response were related to the quality of the contact between the Compeer volunteer and consumer. Implications for future research are discussed. © 2006 Wiley Periodicals, Inc.
Lipopolysaccharide accelerates caspase‐independent but cathepsin B‐dependent death of human lung epithelial cells
Authors: Tang Peter S. , Tsang Melanie E. , Lodyga Monika , Bai Xiao‐Hui , Miller Abigale , Han Bing , Liu Mingyao
Published: August 2006

Caspase‐independent cell death has drawn increasing attention. In the present study, we found that lipopolysaccharide (LPS) accelerated spontaneous death of human lung epithelial A549 cells in a serum‐ and cell density‐dependent manner: while serum starvation has been demonstrated to induce apoptosis in the same cell line, LPS‐induced cell death was only observed in the presence of serum; in addition, the cell death was not observed when the cells were seeded at 10‐ or 100‐fold lower density. The apoptotic features were demonstrated by TUNEL assay, DNA laddering and Annexin V staining. However, treatment of cells with two commonly used pan‐caspase inhibitors, zVAD.fmk or BOC‐D.fmk, failed to block cell death. In contrast, two cathepsin B inhibitors, Ca074‐Me or N‐1845, reduced cell death significantly. A time‐dependent activation of cathepsin B, but not caspase 3, was observed in both control and LPS‐treated cells. Although LPS did not further activate cathepsin B or its release, it increased expression and translocation of apoptosis inducing factor from mitochondria to the nucleus, and increased release of cytochrome c from mitochondria. LPS‐induced cell death was significantly attenuated by either N‐acetyl‐L‐cysteine or pyrrolidine‐dithiocarbamate, both free radical scavengers. Disruption of lipid raft formation with filipin or methyl‐β‐cyclodextrin also reduced apoptosis significantly, suggesting that lipid raft‐dependent signaling is essential. These data imply that confluent cells undergo spontaneous cell death mediated by cathepsin B; LPS may accelerate this caspase‐independent cell death through release of mitochondrial contents and reactive oxygen species. J. Cell. Physiol. 209: 457–467, 2006. © 2006 Wiley‐Liss, Inc.
Policy preferences in fiscal response studies
Authors: Feeny Simon
Published: August 2006

This paper contributes to the fiscal response literature. By appropriately incorporating asymmetric policy preferences, it derives a model that the literature has long been searching for. It proceeds by discussing the implications regarding the results from previous studies. Copyright © 2006 John Wiley & Sons, Ltd.