bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibacterial activity of two canthin‐6‐one alkaloids from Allium neapolitanum
Authors: O'Donnell Gemma , Gibbons Simon
Published: April 2007

The emergence of multidrug‐resistant strains of many human pathogens has led to an urgent need for the discovery and development of new antimicrobial agents. As part of an ongoing investigation into the antibacterial properties of the Alliaceae, the isolation of 1 (canthin‐6‐one), 2 (8‐hydroxy‐canthin‐6‐one) and 3 (5(ζ)‐hydroxy‐octadeca‐6(E)‐8(Z)‐dienioc acid)) from A. neapolitanum, a perennial bulbous herb found in open pastures of the Mediterranean is reported. Compounds 1 and 2 were isolated by Sephadex LH‐20 from fractions exhibiting a positive reaction with Dragendorff's reagent on TLC, compound 3 was isolated after HPLC purification of Sephadex fractions. Structures were elucidated by extensive 1D and 2D NMR experiments and are in accordance with published data, however, the 13C NMR data for compound 2 and the 1H and 13C NMR data for compound 3 are reported here for the first time. Canthin‐6‐one alkaloids are well‐known constituents of the Simaroubaceae and Rutaceae, and display a wide range of biological activities. These metabolites are reported as constituents of the Alliaceae here for the first time, and displayed minimum inhibitory concentrations (MICs) in the range 8–32 µg/mL against a panel of fast‐growing Mycobacterium species and 8–64 µg/mL against multidrug‐resistant (MDR) and methicillin‐resistant (MRSA) strains of Staphylococcus aureus. Compound 3 displayed antimycobacterial activity in the range of 16–32 µg/mL. Copyright © 2007 John Wiley & Sons, Ltd.
Reproductive toxicity of lapachol in adult male Wistar rats submitted to short‐term treatment
Authors: de Cássia da Silveira e Sá Rita , de Oliveira Guerra Martha
Published: April 2007

Lapachol is a therapeutic naphthoquinone, but little is known about its general and reproductive toxicity. In female rats, a high incidence of resorptions and fetal mortality has been reported. This work analyses the effect of the short‐term administration of lapachol on vital and reproductive organs, and sperm production in Wistar rats. Adult animals were treated with 1 mL of lapachol hydroalcohol solution (100 mg/kg of body weight) for 5 days and killed 3 (T1) and 14 days (T2) after the end of treatment. Body and organ weights and sperm production were evaluated. The administration of lapachol significantly reduced the weight of the seminal vesicle (T1 animals). No significant alteration of gamete production, body weight and the weight of the other organs analysed were detected. The results suggest a reproductive toxicity effect of lapachol, indicating the seminal vesicle as a possible target organ. Copyright © 2007 John Wiley & Sons, Ltd.
Excess polarizabilities upon excitation from the ground state to the first dipole‐allowed excited state of diphenylpolyenes
Authors: Ye J. F. , Chen H. , Note R. , Mizuseki H. , Kawazoe Y.
Published: April 2007

This paper discusses the excess polarizabilities upon excitation from the ground state to the first dipole‐allowed excited state (S1) of diphenylpolyenes by using the time‐dependent density functional theory. Two hybrid exchange‐correlation (xc) potentials Becke‐3 Lee‐Yang‐Parr (B3LYP) and Perdew‐Burke‐Ernzerhof (PBE1PBE) were employed. Our calculations indicate that the magnitude of the excess polarizability will decrease while the molecule evolves from the unrelaxed S1 state to the relaxed S1 state. This decreasing trend is found to be independent of substituents, though substituents can change the value of the excess polarizability. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Quantum chemical study of penicillin: Reactions after acylation
Authors: Li Rui , Feng Dacheng , Zhu Feng
Published: April 2007

The density functional theory methods were used on the model molecules of penicillin to determine the possible reactions after their acylation on β‐lactamase, and the results were compared with sulbactam we have studied. The results show that, the acylated‐enzyme tetrahedral intermediate can evolves with opening of β‐lactam ring as well as the thiazole ring; the thiazole ring‐open products may be formed via β‐lactam ring‐open product or from tetrahedral intermediate directly. Those products, in imine or enamine form, can tautomerize via hydrogen migration. In virtue of the water‐assisted, their energy barriers are obviously reduced. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Bayesian and frequentist two‐stage treatment strategies based on sequential failure times subject to interval censoring
Authors: Thall Peter F. , Wooten Leiko H. , Logothetis Christopher J. , Millikan Randall E. , Tannir Nizar M.
Published: April 2007

For many diseases, therapy involves multiple stages, with the treatment in each stage chosen adaptively based on the patient's current disease status and history of previous treatments and clinical outcomes. Physicians routinely use such multi‐stage treatment strategies, also called dynamic treatment regimes or treatment policies. We present a Bayesian framework for a clinical trial comparing two‐stage strategies based on the time to overall failure, defined as either second disease worsening or discontinuation of therapy. Each patient is randomized among a set of treatments at enrollment, and if disease worsening occurs the patient is then re‐randomized among a set of treatments excluding the treatment received initially. The goal is to select the two‐stage strategy having the largest average overall failure time. A parametric model is formulated to account for non‐constant failure time hazards, regression of the second failure time on the patient's first worsening time, and the complications that the failure time in either stage may be interval censored and there may be a delay between first worsening and the start of the second stage of therapy. Four different criteria, two Bayesian and two frequentist, for selecting a best strategy are considered. The methods are applied to a trial comparing two‐stage strategies for treating metastatic renal cancer, and a simulation study in the context of this trial is presented. Advantages and disadvantages of this design compared to standard methods are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Can us locations compete with low‐cost Mexican labor? a location cost analysis of North Carolina and the Yucatan in the sewn bag and case industry
Authors: Sanford Douglas M. , Fink David
Published: April 2007

Several international investment theories hold that production costs in developing countries should be lower than in developed countries for facilities that utilize globally standardized production technology and semi‐skilled labor. This analysis tests this expectation by estimating the relative production costs in a North Carolina site and a Yucatan site of a sewn bag and case manufacturer. Interestingly, no overall location cost advantage is found for the Yucatan site. 1997 John Wiley & Sons, Inc.
A perspective of marketing in central and Eastern Europe
Authors: Czinkota Michael R. , Gaisbauer Helmut , Springer Reiner
Published: April 2007

The transition of Central and Eastern Europe toward a market economy affords new opportunities but also new risks to international marketers. Based on the work of the authors in the region, this article presents a perspective of the economic shifts which have taken place in these countries. A review of the available international marketing options is offered and a framework for the evaluation of market entry and marketing mix strategies which accommodate these shifts is developed. Emphasis is placed on the need for marketers to go beyond purely commercial criteria in their decision making, by considering the long‐term social and economic repercussions of their actions. 1997 John Wiley & Sons, Inc.
Fe2 Pairs as Structural Units in the Indides RE12Fe2In3 (RE = Ho, Er, Tm, Lu)
Authors: Dzevenko Mariya V. , Zaremba Roman I. , Hlukhyy Viktor H. , Rodewald Ute Ch. , Pöttgen Rainer , Kalychak Yaroslav M.
Published: April 2007

The indides RE12Fe2In3 (RE = Ho, Er, Tm, Lu) have been prepared by arc‐melting the elements and subsequent annealing. All compounds were characterized by X‐ray powder diffraction and the Er12Fe2In3 structure was refined from X‐ray single crystal data: I4/mmm, a = 958.8(1), c = 957.8(1) pm, wR2 = 0.0629, 412 F2 values and 22 variables. The 2a site shows In/Fe mixing, leading to the composition Er12Fe2.31In2.69 for the investigated crystal. The structure (new type) derives from a Cu3Au (≡ RE12In4) like arrangement RE12(T2)1In3, where one fourth of the indium sites is substituted by an Fe2 dumb‐bell at an Fe–Fe distance of 224 pm. The Er12Fe2In3 type is discussed in line with the structures of Er6Co2.19In0.81 (≡ RE12(T2)2In2) and Sm12Ni6In (≡ RE12(T2)3In), where two, respectively three indium sites are substituted by transition metal dumb‐bells.
1,3,2‐Diselenaphospholanes with an Anellated Dicarba‐closo‐dodecaborane(12) Unit
Authors: Wrackmeyer Bernd , García Hernández Zureima , Kempe Rhett , Herberhold Max
Published: April 2007

The reaction of the 1,2‐diselenido‐1,2‐dicarba‐closo‐dodecaborane dianion (1) with dichloro(phenyl)phosphane affords the 1,3,2‐diselenaphospholane (2) containing an anellated dicarba‐closo‐docecaborane(12) unit. The phospholane 2 was oxidised by reactions with the elements to the sulfide 3 and the selenide 4, and partial hydrolysis gave a selenophosphonic acid derivative 5 along with the bis(diselane) 6 and decomposition. The reaction of 2 with (ethene)bis(triphenylphosphane)platinum(0) displaces ethene and is accompanied by oxidative addition and rearrangement into the bis(triphenylphosphane)platinum(II) complex 9, in which the chelating unit is linked to platinum via Pt‐Se and Pt‐P(Se) bonds, a rare example of a metallophosphane selenide. The molecular structures of 2 and 3 were determined by X‐ray analysis. The solution‐state structures of the new compounds follow from consistent multinuclear magnetic resonance data (1H, 11B, 13C, 31P, 77Se, 195Pt NMR).
Stanna‐closo‐dodecaborate: The Crystal Structure of [Li(thf)3]2[SnB11H11], Vibrational Spectroscopy, Thermal Analysis and DFT Calculations
Authors: Gädt Torben , Wesemann Lars
Published: April 2007

The lithium salt of stanna‐closo‐dodecaborate was prepared and single‐crystalline material was obtained from tetrahydrofurane. The salt crystallizes as [Li(thf)3]2[SnB11H11] in the monoclinic space group P21/c (a = 15.0608(10) Å, b = 14.0778(8) Å, c = 18.3890(12) Å and β = 110.324(5)°) and both lithium ions are coordinated to triangular cluster faces via B–H–Li bonds. DFT calculations in combination with a natural population analysis reveal that the tin vertex exhibits a positive partial charge while all boron atoms of the stannaborate cluster carry a negative charge. The boron atoms of the first B5‐belt display the largest negative partial charges. Raman and IR spectra of the cesium salt of [SnB11H11]2− reveal that the cluster breathing modes which involve the tin vertex are found at around 250 cm−1. Furthermore, the thermal stability of the group‐14‐heteroborate is remarkably large with a decomposition temperature of above 900 °C as determined with TG/DTA measurements.
Lithium Isotope Separation by 12‐Metallacrown‐3 Complexes
Authors: Grote Zacharias , Wizemann Hans‐Dieter , Scopelliti Rosario , Severin Kay
Published: April 2007

The 12‐metallacrown‐3 complexes [(C6H5Me)Ru(C5H3NO2)]3 (3), [(C6H3iPr3)Ru(C5H3NO2)]3 (4) and [(C6Me6)Ru(C5H3NO2)]3 (5) were synthesizes by reaction of the corresponding [(arene)RuCl2]2 complex with 2,3‐dihydroxypyridine in the presence of base. Addition of LiCl in methanol gave the adducts 3×LiCl, 4×LiCl and 5×LiCl. The complexes 3, 3×LiCl and 4×LiCl were analyzed by single crystal X‐ray crystallography. The ability of the metallacrown complexes to differentiate between the isotopes 6Li+ and 7Li+ was investigated by isotope selective laser graphite furnace atomic absorption spectroscopy. It was found that the macrocycle 5 preferentially binds to the smaller isotope 7Li+.
Linkage Isomerism in Thiophene Cyclometallated Palladium(II) Complexes. Crystal and Molecular Structure of the Isomers [Pd{n‐SC4H2C(H)=NCy}(O2CMe‐O)(PPh3)] (n = 3, 4)
Authors: Adrio Luis A. , Antelo José M. , Fernández Alberto , Pereira Ma Teresa , Tato Mercedes , Vila José M.
Published: April 2007

Treatment of 2‐SC4H3C(H)=NCy, a, or 3‐SC4H3C(H)=NCy, b, with palladium(II) acetate in toluene gave the dinuclear cyclometallated complexes [Pd{n‐SC4H2C(H)=NCy}(O2CMe)]2 (n = 5, 1a; n = 3, 1b; n = 4, 1b′), the latter two as a 1:1 mixture of linkage isomers, whose subsequent reactions produced isomeric mixtures in all cases. Reaction of 1a and 1b, 1b′ with aqueous sodium chloride or bromide yielded the corresponding halide‐bridged complexes [Pd{n‐SC4H2C(H)=NCy}(X)]2 (n = 5: X = Cl, 2a; X = Br, 3a; n = 3,4: X = Cl, 2b, 2b′; X = Br, 3b, 3b′) after metathesis. Reactions of the dinuclear compounds with tertiary phosphines in the appropriate molar ratio gave the mononuclear [Pd{n‐SC4H2C(H)=NCy}(Cl)(PPh3)] (n = 5, 6a; n = 3, 4 4b, 4b′) and [Pd{5‐SC4H2C(H)=NCy}{(Ph2PCH2CH2)2PPh‐P,P,P}](Cl), (5a), and the dinuclear [{Pd[5‐SC4H2C(H)=NCy](O2CMe)}2{μ–Ph2P(CH2)nPPh2}] (n = 2, 7a; n = 3, 8a; n = 4, 9a) complexes. The X‐ray crystal structure of complex 4b, 4b′ is described, establishing the presence of two isomers in the crystal lattice.
Synthesis and Characterization of Lanthanide(III) Nitrate Complexes of an Hexaaza Macrocyclic Ligand
Authors: Fernández‐Fernández M. del C. , Bastida R. , Macías A. , Pérez‐Lourido P. , Valencia Laura
Published: April 2007

The [2+2] barium(II) templated cyclocondensation of 2,6‐diacetylpyridine and ethylendiamine followed by an in situ reduction led to an isomeric mixture of the corresponding saturated macrocycles. The 6S,9S,15R,18R‐meso form of the hexaaza macrocyclic ligand (L) has been obtained by the partial crystallization method. The assignment of the proton and carbon NMR signals was based upon standard COSY, DEPT‐135 and HMQC measurements. The structure of the protonated ligand [H2L](NO3)2·3H2O could be confirmed by X‐ray diffraction. A serie of nitrate lanthanide complexes with L have been prepared. The metal complexes, with general formula [ML](NO3)3·xH2O (M = Nd, Eu, Gd, Tb and Tm), were easily prepared in good yield by direct reaction between the hydrated nitrate metal salt and the macrocyclic ligand. The crystal structure of [NdL(NO3)2](NO3)·H2O has been determined by X‐ray diffraction and shows a mononuclear structure with the neodymium atom in 10‐coordinate with a N6O4 environment. The coordination around the neodymium ion can be described as distorted bicapped cube.
BaSr(NH4)Mg5F15, a Tetragonal Tungsten Bronze Structure with Ammonium Barium Disorder and its Solid Solutions BaxSr2−x(NH4)Mg5F15 (x = 1.8−0.6)
Authors: Kubel F. , Pantazi M.
Published: April 2007

The new fluoride BaSr(NH4)Mg5F15 precipitates as a nanocrystalline powder from aqueous solutions of the alkaline earth ions and ammonium fluoride. The compound crystallizes in the tetragonal tungsten bronze structure type with lattice parameters of a,b = 12.4492(14) Å and c = 3.9421(4) Å (space group P4/mbm [Nr. 127], structure refinement from powder data, RBragg = 4.0 %). Corner‐linked magnesium‐fluoride octahedra form a channel structure which contains one empty triangular channel, one channel filled with Sr2+ [CN = 8+4] and one channel with disordered Ba2+and NH4+ (ratio 1:1) with CN = 7+8. Solid solutions between the composition limits Ba(Ba0.8Sr0.2)(NH4)Mg5F15 and (Ba0.6Sr0.4)Sr(NH4)Mg5F15 were obtained. The crystallite size increases from 15 to 75 nm with increasing barium concentration. The thermal stability between 350 to 450 °C depends on the amount of absorbed (NH4)F. Heated samples show luminescence and phosphorescence.
On Oxohalogeno Niobates(V) M2[Nb3O5X7] (M = NH4, K, Rb, Cs; X = Cl, Br) – New Members of a Compound Family with a Layered Structure
Authors: Beck Johannes , Bordinhão Jairo , Kusterer Christian
Published: April 2007

The reaction of alkali chlorides MCl with NbOCl3 yields melts which on cooling solidify under crystallization. In the case of KCl / NbOCl3, the pink coloured regulus was investigated by powder‐XRD and shown to be biphasic, consisting of K[NbOCl4] (primitive orthorhombic lattice, a = 13.467(2); b = 7.9362(8); c = 14.041(2) Å) and K2[NbOCl5] (F centred cubic lattice, a = 9.8291(2) Å). To a small amount vapour phase transport occurs and colourless crystals of M2[Nb3O5Cl7] (M = K, Rb, Cs) are deposited in the colder parts of evacuated glass tubes containing molten mixtures of MCl and NbOCl3 or MCl, Nb2O5 and NbCl5 in a temperature gradient of 500 °C to 450 °C for some days. Green crystals of (NH4)2[Nb3O5Br7] are obtained as a by‐product in the reaction of NH4Br with NbOBr3 in sealed ampoules at temperatures of 300 °C. All compounds are isotypic and belong to the M2[Nb3O5X7] structure type of which (NH4)2[Nb3O5Cl7] was already known (Schweda, 1997) (monoclinic, C2/c, Z = 4, (NH4)2[Nb3O5Br7] a = 17.8488(6), b = 8.8581(3), c = 11.3376(4) Å, β = 110.572(2)°; K2[Nb3O5Cl7] a = 16.7346(3), b = 8.8558(2), c = 11.0623(3) Å, β = 112.661(1)°; Rb2[Nb3O5Cl7] a = 16.794(14), b = 8.873(5), c = 11.032(8) Å, β = 111.33(6)°; Cs2[Nb3O5Cl7] a = 17.233(6), b = 8.928(3), c = 11.092(3), β = 109.36(2)°). The structures consist of niobium‐centred NbO3Cl3 and NbO4Cl2 octahedra, which share common edges to form a two‐dimensional network of the composition ${\rm [(Nb_{3}O_{5}} X_{7})^{2-}]^{2}_{\infty}$ (X = Cl, Br). These anionic layers are stacked with the cations located between them. The monovalent cations are coordinated exclusively by halogen atoms and have the coordination number ten in form of “edshammar polyhedra”.
Electrochemical Synthesis and Characterization of Cobalt(II), Cobalt(III), and Nickel(II) Complexes with Pyrimidine‐2‐thionato Ligands
Authors: Rodríguez A. , García‐Vázquez José Arturo , Romero J. , Sousa‐Pedrares A. , Sousa A. , Castro J.
Published: April 2007

The electrochemical oxidation of anodic metal (cobalt and nickel) in acetonitrile solutions of the appropriate pyrimidine‐2‐thione derivatives (RpymSH, where R = 4‐CF3, 4,6‐CF3Me, 4,6‐MePh, 4,6‐CF3Ph, 4,6‐Ph2) afforded complexes of composition [M(RpymS)2], M = Co, Ni or [Co(RpymS)3]. When 2,2′‐bipyridine (bipy) or 1,10‐phenanthroline (phen) was added to the electrolytic cell, adducts of cobalt(II) and nickel(II) compounds with these coligands were obtained: [M(RpymS)2bipy] and [M(RpymS)2phen]. All of the compounds were characterized by microanalysis, electronic, vibrational spectroscopy and FAB mass spectrometry, and, in the cases of the compounds [Co(RpymS)3], by 1H and 13C, NMR spectroscopy. The compound [Co(4‐CF3pymS)3] was also characterized by X‐ray diffraction. The crystal structure consists of monomeric molecules in which the central CoS3N3 unit has a slightly distorted octahedral coordination with the ligands adopting a meridional disposition.
Metal‐mediated Ring Opening Reaction of Two Aziridines to give 1,2‐Aminoaziridinoethane Ligands
Authors: Krinninger C. , Ruiz J. C. G. , Nöth H. , Lorenz I.‐P.
Published: April 2007

The reaction of 2,2′‐dimethylaziridine with the carbonyl halogenido complexes [(CO)5MX] (M = Mn; X = Cl, I; M = Re: X = I) results in the formation of the 1,2‐aminoaziridinoethane complexes [(CO)3XM{NH2CMe2CH2N(C2H2Me2)}]. The bis(2,2′‐dimethylaziridine) complexes [(CO)3XM(NHCH2CMe2)2] may act as intermediates. The new asymmetric chelate ligand is the formal dimerization product of 2,2′‐dimethylaziridine, which is formed and stabilized in the coordination sphere of both transition metals. The new complexes have been characterized using elemental analysis, mass, IR and NMR spectra as well as by X‐ray structure analysis. The metal centers exhibit a distorted octahedral configuration with a facial (CO)3M‐arrangement, and the 5‐membered metallacycles show a twist conformation and lie in the trans‐positions with respect to the CO ligands in the equatorial plane. Whereas the Mn‐N bonds to the intact aziridine system are longer (213.3 and 213.8 pm) than those to the NH2 group (206.5 and 207.4 pm), the corresponding Re–N bonds show the opposite trend, whereby the Re–NH2 bonds are shorter (219.0 and 225.8 pm).
The Anions [B24H23]3− and [B36H34]4− from the Thermal Protolysis of [B12H12]2−
Authors: Paetzold Peter , Bettinger Holger F. , Volkov Oleg
Published: April 2007

The thermolysis of the hydrated free acids [H(H2O)m]2[BnHn] (n = 12, 11, 10) is described. The anion [B12H12]2− is transformed into [B24H23]3− at 80 °C and into [B36H34]4− at 90 °C, with [B12H11(OH)]2− as a side‐product. The novel anion [B36H34]4−, isolated after neutralization as a salt with the cation NMe4, is considered by NMR arguments to consist of two icosahedral B12H11 units connected to a central B12H10 unit by BHB bridges. According to an ab initio computation, the two or three icosahedral cages of [B24H23]3− and [B36H34]4−, respectively, are connected by bent BHB‐bridges in the ground‐state. Upon acidification, the anion B11H112− is transformed into nido‐[B11H13(OH)]−, which is completely degraded, when water is removed from the solution of the free acid. The anion [B10H10]2− is degraded into the arachno‐[B9H14]− anion, when the free acid is heated (100 °C) in the presence of oxalic acid.
The High‐Temperature Phases HT‐YPtSn, HT‐GdPtSn, and HT‐TbPtSn
Authors: Freerks Riecken Jan , Heymann Gunter , Huppertz Hubert , Pöttgen Rainer
Published: April 2007

The TiNiSi type high‐temperature (HT) modifications of YPtSn, GdPtSn, and TbPtSn were obtained by rapidly quenching arc‐melted samples. They were investigated by X‐ray diffraction on powders and single crystals: Pnma, a = 716.0(1), b = 453.53(9), c = 795.1(1) pm, wR2 = 0.0432, 419 F2 values for HT‐YPtSn, a = 721.1(6), b = 455.6(4), c = 789.6(8) pm, wR2 = 0.0598, 802 F2 values for HT‐GdPtSn, and a = 716.4(2), b = 453.7(2), c = 794.1(3) pm, wR2 = 0.0390, 629 F2 values for HT‐TbPtSn, with 20 variables per refinement. HT‐YPtSn, HT‐GdPtSn, and HT‐TbPtSn transform to the ZrNiAl type low‐temperature modifications (space group $P{\bar 6}{\rm 2}m$; reconstructive phase transition) by annealing for five days at 800 °C. In all three compounds, the platinum and tin atoms build up three‐dimensional [PtSn] networks (267–284 pm Pt‐Sn in HT‐YPtSn) in which the rare earth metal atoms occupy distorted hexagonal channels.
Electrochemical Synthesis: a Convenient Method for the Preparation of Neutral Metal Complexes with a Thiosemicarbazone Ligand
Authors: Bermejo Manuel R. , González‐Noya Ana M. , Martínez‐Calvo Miguel , Pedrido Rosa , Romero María J. , Fernández M. Isabel , Maneiro Marcelino
Published: April 2007

The interaction of the transition and post‐transition metals manganese, iron, cobalt, nickel, zinc, cadmium and lead, with the ligand 4‐N‐methylthiosemicarbazone‐2‐pyridinecarboxaldehyde (HL) through an electrochemical procedure has been investigated.

The novel complexes obtained via this synthetic route have the general formulae [M(L)2](H2O)n (n = 1‐3.5). The crystal and molecular structures have been determined for the mononuclear complexes [MnL2]·H2O (2), [CoL2] (5), [NiL2]·H2O (7) and [PbL2] (11). Complexes 2, 5 and 7 exhibit a distorted octahedral polyhedron around the metal atom, whilst the lead derivative shows a particular coordination polyhedron that may be regarded as a distorted bipyramidal pentagonal structure, with one apical position filled by the metal lone pair.

All these complexes have been fully characterized by elemental analysis, infrared spectroscopy, mass spectrometry, magnetic and conductivity measurements, and 1H, 113Cd and 207Pb NMR techniques.
Synthesis and Molecular Structure of trans‐[IrCl(coe)(tBu2PH)2] (coe = cis‐cyclooctene)
Authors: Böttcher Hans‐Christian , Graf Marion , Karaghiosoff Konstantin , Mayer Peter
Published: April 2007

The reaction of [{Ir(μ‐Cl)(coe)2}2] (1) (coe = cis‐cyclooctene) with the secondary phosphane tBu2PH afforded, under defined conditions, the novel complex trans‐[IrCl(coe)(tBu2PH)2] (2), which has been characterized by spectroscopic methods as well as by X‐ray diffraction. Compound 2 represents the first isolated and structurally characterized type of complex trans‐[IrCl(coe)L2] (L = phosphane). The compound is presumably isolable because of the convenient electronic effects of the chosen phosphane ligands.
Syntheses and Structures of Solvated Tetrasodiumtetrachalcogenostannates [Na4(en)4][SnE4] (en = 1,2‐diaminoethane; E = Te, Se), and their Reactions Toward Further Ternary or Quaternary Chalcogenometallates [Mn(en)3]2[Sn2Te6]·4H2O or [Na10(H2O)34][Mn4(μ4‐Se)(SnSe4)4]
Authors: Ruzin Eugen , Zimmermann Christian , Hillebrecht Pierre , Dehnen Stefanie
Published: April 2007

A fusion/extraction technique was applied for the syntheses of en solvated (en = 1,2‐diaminoethane) sodium salts of ortho‐chalcogenostannate anions, [Na4(en)4][SnE4] with E = Te (1) or Se (2), possessing homologue composition and similar crystal packing. However, further reactions of 1 and 2 with Mn(OAc)2·4H2O yielded different types of Mn/Sn/E compounds: whereas 1 is converted into an [Mn(en)3]2+ salt of dimeric [Sn2Te6]4− anions (3), the presence of selenium ligands in 2 enables the formation of a ternary anion [Mn4(μ4‐Se)(SnSe4)4]10− in 4, which is the first Na+ salt of this P1‐type anionic cluster. The reactions show both the influence of en ligands on the reaction behavior of ortho‐chalcogenostannate anions and enhance the knowledge of the complex influences onto molecular structures of supertetrahedral cluster anions. Compounds 1–4 were structurally determined by means of single crystal X‐ray diffractometry; lattice dimensions at 203 K: 1 (monoclinic space group P21/c): a: 7.5988(15) Å, b: 26.496(5) Å, c: 13.710(3) Å, β: 92.84(3)°, V: 2756.8(9) Å3; 2 (tetragonal space group P41212): a: 13.0900(19) Å, c: 14.548(3) Å, V: 2492.8(7) Å3; 3 (triclinic space group $P{\bar 1}$): a: 9.3109(19) Å, b: 9.4345(19) Å, c: 12.800(3) Å α: 108.36(3)° β: 98.43(3)° γ: 103.82(3)° V: 1005.8(4) Å3; 4 (triclinic space group P1): a: 14.903(3) Å, b: 15.189(3) Å, c: 15.339(3) Å, α: 90.47(3)°, β: 90.61(3)°, γ: 91.54(3)°, V: 3470.9(12) Å3.
Supranormal dietary folic acid supplementation: effects on methionine metabolism in weanling rats
Authors: Achón M. , Alonso-Aperte E. , Úbeda N. , Varela-Moreiras G.
Published: April 2007

There are nationwide folic acid (FA) fortification programmes of staple foods established or under consideration in order to prevent neural tube defects. Universal FA fortification still remains controversial because of the concern that additional FA in the diets of population groups (e.g. children and elderly) not initially targeted for fortification may suffer adverse effects. However, dietary surveys regarding folate generally deal with adults and little is known about the consumption and long-term effects of fortified food and supplements in growing individuals. Recent reports from our laboratory show several effects of high-dose folate supplementation in rats. In the present work, we studied the effect of FA on the methionine cycle in weanling (3-week-old) male rats after 4 weeks of supplementation with 40 mg FA/kg dietv.control (1 mg FA/kg diet). FA supplementation resulted in a reduction of homocysteine and creatinine concentrationsv.control group. FA supplementation did not alterS-adenosylmethionine/S-adenosylhomocysteine ratio, DNA methylation, enzymatic activities or concentrations of vitamins involved in the nutritional regulation of the methionine cycle, except for folate. FA supplementation of 40 mg/kg did not lead to hepatic or renal damage. In conclusion, there were no apparent adverse effects on one-carbon metabolism after FA supplementation in the studied conditions.
DENKYIRA IN THE MAKING OF ASANTE C. 1660–1720
Authors: McCASKIE T. C.
Published: April 2007

This article examines the complex and fluid relationship between Denkyira and Asante in the period c. 1660–1720 that saw the former supplanted by the latter as the leading power among the Twi-speaking Akan peoples of the central southern Gold Coast (Ghana). Dense oral traditions supplemented by a range of other materials are used to identify the site of the ancient Denkyira capital of Abankeseso, and to give an account of the settlements that served it and the gold resources that supported it. These same sources provide a detailed understanding of the reasons for defections from Denkyira to Asante, and how this process contributed to the first Asantehene Osei Tutu's epochal military victory over Denkyirahene Ntim Gyakari at Feyiase (1701). Asante policy towards defeated Denkyira is then discussed, and the legacy of the events described is considered. At a general level, this article makes a case for looking in detail and depth at the local conditions that gave rise to particular – and particularly complex – sociopolitical arrangements, and argues that studies of this kind can advance understanding of the formation and nature of polity and identity in precolonial Africa.
TANZANIA'S OPERATION VIJIJI AND LOCAL ECOLOGICAL CONSCIOUSNESS: THE CASE OF EASTERN IRAQWLAND, 1974–1976
Authors: LAWI YUSUFU QWARAY
Published: April 2007

Tanzania's Ujamaa villagization campaign of 1973–6 was one of the greatest social experiments in postcolonial Africa. Occurring during a time of continuing hope for a better future for the nation, the experiment aimed to improve the lives of the majority of rural Tanzanians. Despite this noble intention, the attempt at rural modernization failed miserably in many respects. Discussions of these failures have tended to give prominence to tangible explanations, ignoring more nuanced and qualitative issues, including environmental concerns based on local cosmologies. In an attempt to fill this gap, the present article uses a case study of eastern Iraqwland in northern Tanzania to explore local articulations of the compulsory villagization campaign and to interpret them in light of ecological perspectives that were prevalent at the time in Iraqw village communities.
SUMMARY: PAPERS PRESENTED AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 Challenges to international wheat improvement
Authors: REYNOLDS M. P. , HOBBS P. R. , BRAUN H. J.
Published: April 2007

Wheat is grown on 210 million ha throughout the world producing approximately 600 million tonnes of grain (10 year average; FAO 2005) and providing on average one fifth of the total calorific input of the world's population (FAO 2003). For some regions such as North Africa, Turkey and Central Asia, wheat provides half of total dietary energy intake. Of the cultivated wheat area, half is located in less developed countries where there have been steady increases in productivity since the green revolution, associated with genetic improvements in yield potential, resistance to diseases and adaptation to abiotic stresses (Reynolds & Borlaug 2006a, b) as well as better agronomic practices (Derpsch 2005). Nonetheless, challenges to wheat production are still considerable, especially in the developing world, not only because of increased demand but also because of the increased scarcity of water resources (Rosegrant 1997; WMO 1997), ever more unpredictable climates (Fischer et al. 2002), increased urbanization and loss of good quality land away from agriculture (Hobbs 2007), and decreased public sector investment in agriculture and rural affairs (Falcon & Naylor 2005). To meet demand in a sustainable way, more resources are required to breed a new generation of genetically improved cultivars as well as implement resource-conserving agronomic management practices.
PAPER ADAPTED FROM PRESENTATION AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 U-impact pathway for diagnosis and impact assessment of crop improvement
Authors: DIXON J. , HELLIN J. , ERENSTEIN O. , KOSINA P.
Published: April 2007

Agricultural research has contributed enormously to poverty reduction and increased food security worldwide. Wheat crop improvement is a good example of this contribution. Public investments in wheat research from the Green Revolution onwards led to significant productivity increases: following the widespread adoption of semi-dwarf varieties, annual yield growth rates peaked at 2·75% p.a. in the 1980s. Since then, public and private investments in crop (including wheat) research have been modest despite the potential of such research to contribute substantially to the first Millennium Development Goal (MDG) of halving hunger and poverty by 2015. Drawing on a wide spectrum of recent literature, the present paper broadens the usual frame of reference for diagnosing the adoption of improved technology and measuring impact. The adoption of improved varieties and management practices is influenced on the supply side by the nature and performance of the input delivery pathway from research to the farm (input value chains), and on the demand side by the characteristics of the farm household system and the marketing or value-adding chains from the farm to the consumer (output value chains). These three elements (input value chains, farm household system characteristics, and output value chains) can be viewed as a U-impact pathway. This pathway determines the rate and extent of adoption of improved varieties and practices, the magnitude of direct and indirect impacts, and the potential for feedback loops leading to improved functioning of the input and output value chains. The U-impact pathway provides a framework to identify an expanded set of beneficiaries from crop improvement which extend beyond the common focus on producers and final consumers; conventional surplus analysis can then be used to estimate the wider benefits to crop improvement. Additional metrics may be needed to estimate impact related to non-economic benefits, such as poverty, health and social capital. The implication of this fuller accounting of impacts is that the benefits accruing to agricultural research may be greater, and more widely distributed across the economy, than previously recognized by research managers and policy-makers. This strengthens the case for maintained or increased public and private sector investment in crop improvement.
Nasopharyngeal carcinoma presenting as carotidynia in an 18-year-old patient
Authors: Ellul D , Cutajar J , Borg xuereb H , Said M
Published: April 2007

Introduction:

Nasopharyngeal carcinoma can present with a variety of symptoms the most common being painless cervical lymph node metastases, epistaxis and conductive hearing loss.

Case report:

We report a case of an 18-year-old male patient presenting to the ENT department with left sided carotidynia – severe pain in the neck radiating up to his ear. He had a small, exquisitely tender lump just below the bifurcation of the left common carotid artery. After the appropriate investigations he was diagnosed with nasopharyngeal carcinoma.

Discussion:

In a literature search on Medline and Pubmed we found no reported cases of nasopharyngeal carcinoma presenting with carotidynia, nor was carotidynia ever found to be associated with nasopharyngeal carcinoma.

Conclusion:

We believe that this is the first reported case of such a presentation of nasopharyngeal carcinoma.
Role of otoacoustic emission in children with middle-ear effusion and grommets
Authors: Saleem Y , Ramachandran S , Ramamurthy L , Kay N J
Published: April 2007

Objective: To evaluate the role of otoacoustic emission in children with middle-ear effusion and grommets.

Materials and methods: A prospective study was carried out on a total of 90 ears. All children listed for grommet insertion had a pre-operative and post-operative (three to six months after grommet insertion) pure tone audiometry, tympanometry and otoacoustic emission recorded. A comparison was made between pure tone audiometry and otoacoustic emission both pre-operatively and post-operatively.

Results: Pre-operatively, 63 ears had an abnormal pure tone audiometry of which 59 had absent otoacoustic emission. Therefore the sensitivity of otoacoustic emission in detecting a conductive loss was 59/63 = 94 per cent (95 per cent confidence interval 85 to 98 per cent). All 27 ears with normal hearing pre-operatively had normal otoacoustic emission. The specificity of otoacoustic emission was 27/27 = 100 per cent, (95 per cent confidence interval, 88 to 100 per cent). The positive predictive value was 59/59 = 100 per cent (95 per cent confidence interval, 94 to 100 per cent). After three to six months all post-operative patients with grommets had a normal pure tone audiometry and otoacoustic emission. So both pure tone audiometry and otoacoustic emission were strongly related both in patients with middle-ear effusion and in patients with grommets.

Conclusion: As the demonstration of hearing in young and difficult-to-test children can be problematic and time-consuming, we suggest that otoacoustic emission can be used as an alternative to pure tone audiometry in patients with middle-ear effusion and grommets.
Sudden sensorineural hearing loss in a patient with primary antiphospholipid syndrome
Authors: Kang K-T , Young Y-H
Published: April 2007

Objective:

Despite multiple systemic manifestations, sudden sensorineural hearing loss in a patient with antiphospholipid syndrome is rarely reported.

Patient:

A 46-year-old man with primary antiphospholipid syndrome had a sudden onset of hearing loss and tinnitus in the right ear in December 2005, because he discontinued use of warfarin and acetylsalicylic acid for a few days.

Results:

Audiometry revealed saucer-type sensorineural hearing loss with a pure tone average of 73 dB in the right ear, and flat-type hearing loss with a pure tone average of 25 dB in the left ear. Electronystagmography displayed multiple central signs and bilateral canal paresis, while a vestibular evoked myogenic potential test revealed bilateral delayed responses. After admission, the patient was re-treated with warfarin and acetylsalicylic acid. Follow-up audiometry showed recovery of right-sided hearing, with a pure tone average of 12 dB, three days after presentation.

Conclusion:

Consensus exists on the effectiveness of anticoagulant agents in aiding a favourable outcome of sudden sensorineural hearing loss in patients with antiphospholipid syndrome.
Construction of a family of Moufang loops
Authors: CURTIS ROBERT T.
Published: April 2007

This paper is an excerpt from a Rayleigh essay submitted at the University of Cambridge in January 1970. We reproduce it now as it gives a general construction of a family of Moufang loops to which all bar one of the finite subloops of the Cayley algebra ${\mathbb O}$ belong. These subloops were classified up to isomorphism in the original essay, but are classified up to equivalence under the action of the group of symmetries of $\mathbb O$ in Boddington and Rumynin [1]. Explicitly, given a group G with an element a such that a2=1 in its centre, we construct a Moufang group $\hat G$ in which G has index 2. $\hat G$ will be non-associative unless G is abelian.
The growth of univalent functions with an initial gap II
Authors: AHARONOV DOV , HAYMAN WALTER K.
Published: April 2007

We consider the class Sp of functions

univalent in the unit disk Δ.

In [1] it was shown that if f∈Sp and p is large,
(0.1)
Here we show that there exists f in Sp for p=1,2,. . . such that

where C0 is a positive absolute constant.
A star-graph model via operator extension
Authors: PAVLOV B.
Published: April 2007

One usually assumes that the Schrödinger operator on a thin quantum network (“fattened graph”) can be simulated by the ordinary Schrödinger operator on the corresponding one-dimensional quantum graph. On the other hand, each quantum graph can be constructed of standard elements – star graphs. We prove that a thin star-shaped quantum network which consists of a compact domain and a few straight semi-infinite quantum wires, with a two-dimensional Schrödinger operator on it, can be simulated by the corresponding solvable model in form of a one-dimensional star graph: an outer space, with an ordinary Schrödinger operator on the leads, a resonance vertex supplied with an inner space and a finite matrix in it and an appropriate boundary condition connecting the inner and outer components of elements from the domain of the model. The model is (locally) quantitatively consistent: the scattering matrix of the model on a certain spectral interval serves an approximation of the scattering matrix of the network. The role of the constructed star-graph model as a “jump-start” in analytic perturbation procedure on continuous spectrum is discussed.
Schwarz–Christoffel mappings to unbounded multiply connected polygonal regions
Authors: CROWDY DARREN
Published: April 2007

A formula for the generalized Schwarz–Christoffel conformal mapping from a bounded multiply connected circular domain to an unbounded multiply connected polygonal domain is derived. The formula for the derivative of the mapping function is shown to contain a product of powers of Schottky–Klein prime functions associated with the circular preimage domain. Two analytical checks of the new formula are given. First, it is compared with a known formula in the doubly connected case. Second, a new slit mapping formula from a circular domain to the triply connected region exterior to three slits on the real axis is derived using separate arguments. The derivative of this independently-derived slit mapping formula is shown to correspond to a degenerate case of the new Schwarz–Christoffel mapping. The example of the mapping to the triply connected region exterior to three rectangles centred on the real axis is considered in detail.
Algebraicity of L-values for elliptic curves in a false Tate curve tower
Authors: BOUGANIS THANASIS , DOKCHITSER VLADIMIR
Published: April 2007

Let E be an elliptic curve over ${\mathbb Q}$, and τ an Artin representation over ${\mathbb Q}$ that factors through the non-abelian extension ${\mathbb Q}(\sqrt[p^n]{m},\mu_{p^n})/{\mathbb Q}$, where p is an odd prime and n, m are positive integers. We show that L(E,τ,1), the special value at s=1 of the L-function of the twist of E by τ, divided by the classical transcendental period Ω+d+|Ω−d−|ε(τ) is algebraic and Galois-equivariant, as predicted by Deligne's conjecture.
Strongly-cyclic branched coverings and the Alexander polynomial of knots in rational homology spheres
Authors: KODA YUYA
Published: April 2007

Let K be a knot in a rational homology sphere M. In this paper we correlate the Alexander polynomial of K with a g-word cyclic presentation for the fundamental group of the strongly-cyclic covering of M branched over K. We also give a formula for the order of the first homology group of the strongly-cyclic branched covering.
Geotechnical in situ characterization of subaquatic slopes: The role of pore pressure transients versus frictional strength in landslide initiation
Authors: Stegmann Sylvia , Strasser Michael , Anselmetti Flavio , Kopf Achim
Published: April 2007

Mineralogical composition and pore fluid pressure are the crucial controls for mechanical stability of water‐saturated sediments. Their in situ measurements were undertaken in earthquake‐triggered slope deposits in Lake Lucerne (Switzerland) in addition to geophysical characterization and laboratory index properties, shear and consolidation experiments on core. Two lithological units were identified: A weak, lightly underconsolidated section of postglacial silty clays overlies overconsolidated fine‐grained glacial deposits with coarser components and excess fluid pressure (ca. 2.5× higher than in the hanging wall clay). In the event of an earthquake, hydrofracturing in the overconsolidated section facilitates an upward pore pressure pulse to the base of the softer, less stable unit. Here, excess pore pressure initiates sliding along a failure plane at the lithological boundary, causing the entire postglacial sedimentary section to slip downslope. We propose that many submarine landslides at active and passive continental margins may follow this mechanism of pore pressure‐induced failure.
Ultrasonic properties of granular media saturated with DNAPL/water mixtures
Authors: Ajo‐Franklin J. B. , Geller J. T. , Harris J. M.
Published: April 2007

We present the results of four experiments investigating the ultrasonic properties of granular materials partially saturated with trichloroethylene (TCE), a dense non‐aqueous contaminant. P‐wave velocity measurements were made under in situ effective stress conditions using a pulse transmission cell at ≈250 kHz. Two synthetic samples and two natural aquifer cores were fully saturated with water and then subjected to an axial injection of TCE. The resulting measurements show reductions in P‐wave velocity of up to 15% due to contaminant saturation. A theoretical model combining Gassmann fluid substitution and Hill's equation was used to estimate the effects of DNAPL saturation; this model underpredicted observed reductions in velocity at high TCE saturations. A linear relationship, expressed in terms of volumetric contaminant fraction, provided an excellent empirical fit to the laboratory measurements.
Magnetic field visualization of magnetic minerals and grain boundary regions using magneto‐optical imaging
Authors: Bobyl Alexander V. , Podladchikov Yuri Y. , Austrheim Håkon , Jamtveit Bjørn , Johansen Tom H. , Shantsev Daniel V.
Published: April 2007

Magneto‐optical imaging based on the Faraday effect has been used to characterize magnetic minerals embedded in a nonmagnetic matrix. We have studied magnetite grains and magnetite‐magnetite grain boundary regions in samples of skarns and serpentinites. Distributions of the remanent magnetic field were measured across at the surface of polished thin sections kept at room temperature. The magneto‐optical images resolve directly magnetic structures on length scales ranging from millimeter down to micrometer, thereby revealing the shape and arrangement of the magnetite grains and allow determination of the grain magnetization. We find that (1) for the skarns the intergrain interactions do not affect the magnetic properties of magnetite grains within 0.6–60 μm of each other, while the saturation remanence decreases weakly with increasing grain size from 40 μm to 0.6 mm, and (2) for the serpentinites the magnetic properties of the stripes are size‐dependent due to variations in chemical composition.
Path‐averaged rainfall estimation using microwave links: Uncertainty due to spatial rainfall variability
Authors: Berne A. , Uijlenhoet R.
Published: April 2007

Microwave links can be used to estimate the path‐averaged rain rate along the link when precipitation occurs. They take advantage of the near proportionality between the specific attenuation affecting the link signal and the rain rate. This paper deals with the influence of the spatial variability of rainfall along the link on the accuracy of the rainfall estimates. We focus on single‐polarization single‐frequency links operating at frequencies ranging from 5 to 50 GHz and with path lengths ranging from 500 m to 30 km. A stochastic simulation framework is used to investigate the frequency at which the linearity occurs (found to be about 30 GHz) for intense Mediterranean precipitation. In addition, the error associated with path‐averaged rain rate estimates is being quantified. For instance, the bias is found to be in the order of −15% with an uncertainty of about 10% for microwave links described in the recent literature.