bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymetallated 4‐tert‐Butylcalix[4]arene Complexes of Sodium and Potassium Stabilized by Crown Ethers: Syntheses, Structures and Activation of Carbon Dioxide
Authors: Fischer Reinald , Görls Helmar , Walther Dirk
Published: March 2004

4‐tert‐Butylcalix[4]arene and 18‐crown‐6 react with NaH in THF to form the complex [(18‐crown‐6)(THF)Na4(4‐tert‐butylcalix[4]arene‐4H)]2·3THF (1). Analogously, the reaction with 4‐tert‐butyltetrathiacalix[4]arene in DMF results in the formation of [(18‐crown‐6)Na(dmf)1.5]2[(4‐tert‐butyltetrathiacalix[4]arene‐4H)2Na6(dmf)2] (2) The X‐ray analysis of 1 shows an Na6O6 skeleton consisting of two fused open heterocubanes. Two Na+ ions are encapsulated in the cavities of the calix[4]arene units. Additionally, two peripheral Na+ ions, each surrounded by a crown ether and one THF ligand, are connected to the central Na6O6 skeleton by one bridging oxygen of the calix[4]arene. In contrast, 2 contains the highly symmetrical anion [(4‐tert‐butyltetrathiacalix[4]arene‐4H)2Na6(dmf)2]2− and crown‐ether‐stabilized cations. While 1 shows a dynamic process in solution above 40 °C, the structure of the highly symmetrical compound 2 remains stable at higher temperatures. The solid‐state structure of the potassium complex [(dibenzo‐18‐crown‐6)K4(4‐tert‐butylcalix[4]arene‐4H)(THF)3]2·4THF (4) is similar to 1; however, the calix[4]arene units in the open heterocubane structure of 4 are shifted less than half a diameter to one another than in the sodium complex 1. According to the 1H NMR spectra complex 3a, containing 18‐crown‐6, has a very similar structure to the related complex 4. Both 1 and 4 absorb carbon dioxide in THF and are active CO2‐transfer reagents towards 2‐fluoropropiophenone; complex 2 is much less active. This clearly demonstrates the subtle influence of the structure of the alkali metal complexes on the CO2 reactivity in these types of compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis and Magnetic Properties of Single‐Crystals of MnFe2O4 Nanorods
Authors: Wang Jun , Chen Qianwang , Hou Binyang , Peng Zhenmeng
Published: March 2004

Single‐crystals of MnFe2O4 nanorods with an average diameter of 20 nm and length of 250 nm were synthesized by a hydrothermal process at 180 °C after 12 h. High‐resolution transmission electron microscopy (HRTEM) and electron diffraction (ED) analysis revealed that the nanorods grow along the [110] axis, which is one of the easy magnetization axes of the material MnFe2O4. It was found that the nanorods exhibited a saturation magnetization (Ms) of 68.02 emu/g, which is much higher than that of quasi‐spherical particles of MnFe2O4, prepared by other approaches such as solid‐state reaction methods (Ms = 36.7 emu/g), and coprecipitation processes followed by annealing in vacuo at 400 °C (Ms = 24.4 emu/g). The oriented growth along the easy magnetization axis of MnFe2O4 was suggested to be responsible for the improvement of magnetic properties of MnFe2O4 nanorods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Electronic Structure of (Diiminopyridine)cobalt(I) Complexes
Authors: Knijnenburg Quinten , Hetterscheid Dennis , Kooistra T. Martijn , Budzelaar Peter H. M.
Published: March 2004

DFT calculations show that square‐planar LCoIR complexes of a diiminopyridine ligand are best regarded as containing low‐spin CoII antiferromagnetically coupled to a ligand radical anion. The lowest triplet state, corresponding to a 3d⇄π* excitation, is calculated to be only a few kcal/mol above the ground state, and is thermally accessible. The anomalous 1H NMR chemical shifts of the LCoR complexes are suggested to be due to thermal population of the triplet state at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Alkali‐Metal‐Directed Hydrolytic Condensation of Trifunctional Phenylalkoxysilanes
Authors: Pozdniakova Yulia A. , Lyssenko Konstantin A. , Korlyukov Alexandr A. , Blagodatskikh Inessa V. , Auner Norbert , Katsoulis Dimitris , Shchegolikhina Olga I.
Published: March 2004

The alkali‐metal‐directed hydrolysis of phenyltrialkoxysilanes, PhSi(OR)3 (R = Me, Et, nBu), was performed under various reaction conditions. The alkali metal ions were used both as templating entities and as structural elements. The crystalline sodium and potassium phenylsiloxanolates (Na‐PhS and K‐PhS) were obtained in two different molecular compositions based on a cis‐tetraphenylcyclotetrasiloxanolate, cis‐[PhSi(O)O−]4, or on a cis‐triphenylcyclotrisiloxanolate, cis‐[PhSi(O)O−]3, anions assembled into a chain or double‐layer supramolecular structure through coordination with alkali cations and hydrogen‐bonding contacts. Conditions for selective preparation of crystalline Na‐PhS or K‐PhS of both structural types were identified. The molecular and crystal structures of [(Na+)3{PhSi(O)O−}3]·8H2O (2), [(Na+)3{PhSi(O)O−}3]·4H2O·1EtOH (3) and [(K+)3{PhSi(O)O−}3]2·7H2O·3MeOH (4) were determined by single‐crystal X‐ray analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
EuIII Luminescence in a Hygroscopic Ionic Liquid: Effect of Water and Evidence for a Complexation Process
Authors: Billard Isabelle , Mekki Soufiane , Gaillard Clotilde , Hesemann Peter , Moutiers Gilles , Mariet Clarisse , Labet Alexandre , Bünzli Jean‐Claude G.
Published: March 2004

The spectroscopic characteristics (excitation, emission and lifetime) of EuIII dissolved in 1‐methyl‐3‐butylimidazolium bis(trifluoromethanesulfon)imide (BumimTf2N) are reported. In a first series of experiments, the effect of the presence of water in BumimTf2N was examined. It appears that non‐degassed solutions are most probably inhomogeneous, displaying large water clusters leading to an intense diffusion of the red light of an He:Ne laser. In these samples, the Eu emission spectrum is close to that observed in slightly acidic aqueous solutions. In contrast, when the samples were degassed the solution appeared homogeneous and water can be considered as a competitive ligand for the first coordination sphere of Eu. In a subsequent series of experiments, tetrabutylammonium chloride (TBACl) was added to the solution and the resultant species investigated. The ensuing enhancement in the metal‐centered luminescence has been interpreted in terms of changes in the inner coordination sphere of the EuIII ion and possible structures are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Peripherally Metallated Porphyrins: the First Examples of meso‐η1‐Palladio(II) and ‐Platinio(II) Complexes with Chelating Diamine Ligands
Authors: Hartnell Regan D. , Arnold Dennis P.
Published: March 2004

The oxidative addition of bis(dibenzylideneacetone)platinum(0) to meso‐bromo‐5,15‐diarylporphyrins in the presence of PPh3 has been shown to be an effective way of synthesising η1‐organoplatinum porphyrins in high yields. This methodology has been extended to synthesise various palladio‐ and platinioporphyrins that utilise bidentate nitrogen donor ligands [N,N,N′,N′‐tetramethylethylenediamine (tmeda) and 2,2′‐bipyridyl (bpy)] in order to enforce a cis configuration at the metal centre. The products were characterised by multinuclear NMR and UV‐Vis spectroscopy as well as fast‐atom bombardment and high‐resolution electrospray ionisation mass spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Novel Layered Lead(II) Aminodiphosphonates with Carboxylate‐Sulfonate and 1,3,5‐Benzenetricarboxylate Ligands as Pendant Groups or Intercalated Species
Authors: Ying Shao‐Ming , Mao Jiang‐Gao
Published: March 2004

The hydrothermal reaction of lead(II) carbonate with 3‐sulfobenzoic acid, 3‐HO3S−C6H4−CO2H, and isopropylimino‐bis(methylenephosphonic acid), (CH3)2CHN(CH2PO3H2)2 (H4L1), gave a new layered lead(II) carboxylate‐phosphonate, Pb7(3‐O3S−C6H4−CO2)(L1)3(H2O)2·2H2O (1), whereas the hydrothermal reaction of lead(II) carbonate with 1, 3,5‐benzenetricarboxylic acid (H3BTC) and N‐cyclohexylimino‐bis(methylenephosphonic acid), C6H11N(CH2PO3H2)2 (H4L2), afforded a layered complex, Pb3(HL2)(H2L2)(H2BTC)(H2O)·H3BTC·H2O (2). The structure of complex 1 contains <010> lead(II) carboxylate‐phosphonate hybrid layers, with the sulfonate group of the carboxylate‐sulfonate ligand as the pendant group. In complex 2, the lead(II) ions are interconnected through bridging diphosphonate ligands, and results in the formation of a lead(II) diphosphonate slab, which are further interlinked via hydrogen bonds between non‐coordinated phosphonate oxygen atoms to form a <001> layer. The doubly protonated H2BTC anion is bidentately chelated to a lead(II) ion through a carboxylate group, whereas the neutral H3BTC ligand is intercalated between two layers, forming hydrogen bonds with the non‐coordinated carboxylate groups of the H2BTC anion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Aminomethyl and Aminoacetyl Complexes of Palladium(II), Platinum(II), Iron(II) and Rhenium(I) with N‐Phthaloyl as Amino Protecting Group and Mechanistic Studies on the Palladium‐Catalyzed Amidocarbonylation
Authors: Enzmann Armin , Eckert Markus , Ponikwar Walter , Polborn Kurt , Schneiderbauer Stefan , Beller Matthias , Beck Wolfgang
Published: March 2004

New aminomethyl and aminoacetyl complexes with N‐phthaloyl as the amino protecting group were synthesised by oxidative addition of N‐phthaloylmethyl or ‐acetyl halide to carbonylmetallates or to Pd(PPh3)4 or [Pt(C2H4)(PPh3)2] to give [Re{C(O)CH2N‐phthaloyl}(CO)5] (1), [FeCp(CH2N‐phthaloyl)(CO)2] (2), [FeCp{C(O)CH2N‐phthaloyl}(CO)2] (3), trans‐[PdBr(CH2N‐phthaloyl)(PPh3)2] (4) and trans‐[Pd{C(O)CH2N‐phthaloyl}(X)(PPh3)2] (X = Br, Cl; 5, 6). The bis(phosphane) complexes [Pd(CH2N‐phthaloyl)(X)(R2PCH2CH2PR2)] and [Pd{C(O)CH2N‐phthaloyl}(X)(R2PCH2CH2PR2)] (X = Cl, Br; R = Ph, C6H11) 8−13 were obtained by ligand exchange from 4, 5 or 6 with the corresponding bis(phosphanes). Halide abstraction from 4, 5, 6, 10, 11 or 12 gives the cationic complexes 14 and 15 with formation of a five‐membered chelate ring which includes one carbonyl atom of the phthaloyl group. The reaction of 6 with the tridentate ligand PhP(CH2CH2PPh2)2 affords the five‐coordinate complex 16 and from [Pt(C2H4)(PPh3)2] and organic halides the platinum(II) complexes trans‐[Pt(CH2N‐phthaloyl)(Cl)(PPh3)2] (17) and [PtC(O)CH(CH2Ph)N‐phthaloyl(Cl)(PPh3)2] (18) were isolated. The structures of 2, 11, 14, 15 and 16 were determined by single‐crystal X‐ray analysis. The mechanism of the palladium‐catalysed amidocarbonylation was studied using phthalimide, formaldehyde and CO as a model system which gives N‐phthaloylglycine in good yield. The proposed elementary steps in the palladium‐catalysed amidocarbonylation could be verified by use of the possible intermediates phthaloyl‐NCH2OH and phthaloyl‐NCH2Br as substrates, by oxidative addition of phthaloylmethyl bromide to Pd0, by insertion of CO into the palladium‐carbon‐bond of 4 and 8 with formation of 5 or 9, respectively, and by use of the isolated possible intermediates 4, 5 and 14 as catalysts. Thus, all crucial steps of the palladium‐catalysed amidocarbonylation with the model system phthalimide/formaldehyde/CO have been verified for the first time. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Quantum Chemical Studies of Neutral and Ionized DyX, DyX2, and DyX3 Species (X = F, Cl, Br, I) and the Implications for the Mass Spectra of Gaseous DyX3
Authors: Saloni Julia , Roszak Szczepan , Hilpert Klaus , Miller Mirosław , Leszczynski Jerzy
Published: March 2004

The mass spectrum pattern of DyF3(g) and the appearance potentials for identified ions were measured and compared with the respective data obtained previously for DyCl3, DyBr3, and DyI3. The structural parameters, total energies, and vibrational frequencies of DyX3, DyX2, and DyX (X = F, Cl, Br, I) neutral and single ionized species were determined by quantum‐chemical studies. The theoretical appearance potentials of different ions, calculated from energies of gaseous species, are in the good agreement with the experimental data. Fragmentation energies of the DyXn+ ion, where n = 1, 2, 3, were computed and compared with the mass spectra patterns of the respective vapour species. A theoretical electron population analysis indicates the involvement of the s and f valence electrons of Dy in the bond formation as well as in the ionization processes. The σ‐back donation from halogen atoms to the dysprosium center partially compensates the electron density loss. The ionization strengthens the bonding in the DyX and DyX2 molecules. The ionization of DyX3 destroys the C3v symmetrical structure due to the Jahn−Teller effect. Contrary to the other studied systems, the open shell character of DyX3+ arises not only from unpaired electrons of dysprosium but also from electron density on halogen atoms. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Solid‐State Lanthanoid‐Assisted Hydrolysis of the Solvolytically “Inert” [AsF6]− Ion
Authors: Ponikvar Maja , Sedej Borka , Liebman Joel F.
Published: March 2004

Results of elemental chemical analyses of the coordination compounds of the type LnFn(AsF6)3‐n (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) indicated unexpectedly low stability of the generally highly hydrolytically stable [AsF6]− ion. Experiments conducted on model compounds of the type NdFn(AsF6)3‐n have shown that hydrolysis proceeded instantaneously during the reaction of the solid compound with water. The ligand substitution catalysis of the compounds is explained in terms of the distortion of the [AsF6]− octahedra earlier shown by vibrational spectroscopy. The study contrasts formally related reactions on the solid−solvent interface as opposed to those in homogeneous solution. A new look at some long studied and well‐known inorganic species is offered. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Construction of P−O/P−N Ligands on Platinum and Palladium
Authors: Bergamini Paola , Bertolasi Valerio , Milani Federico
Published: March 2004

A variety of diphenyldiphosphinites have been prepared in a very stable form as PtII or PdII complexes by adding diols to a solution containing cis‐[MCl2(PPh2Cl)2] (M = Pt or Pd) preformed in situ from cis‐[MCl2(1,5‐COD)] (M = Pt; M = Pd) and PPh2Cl. This synthetic pathway can be used for diphosphinites derived from aliphatic 1,2 and 1,3 diols and also from the aromatic catechol. Besides the P−O bond, it is also shown here that the P−N bond can also be formed via nucleophilic attack of an amine group on coordinated PPh2Cl in the presence of a base resulting in some AMPP and BAMP complexes of PtII and PdII. The X‐ray crystal structures of the [cis‐1,2‐cyclohexanediyl bis(diphenylphosphinite)]platinum dichloride, of the AMPP palladium complex from (1R,2S)‐(−)‐norephedrine and of the BAMP palladium complex [P,P′‐diphenyl‐1,2‐cyclohexanediylbis(imino)bisphosphane]palladium dichloride have been determined. The chemical and optical stabilities of many complexes in solution have been monitored by 31P NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Configuration of Octahedral Metal Compounds − Equilibrium, Crystal and Molecular Structure of Nickel(II) Complexes of Linear N2O4, N4S2 or N6 Donors Set Atoms Ligands
Authors: Mohamadou Aminou , Jubert Caroline , Gruber Nathalie , Barbier Jean‐Pierre
Published: March 2004

Two new nickel(II) complexes of symmetric hexadentate mixed‐ligand N,O [1,12‐bis(2‐pyridyl)‐5,8‐dioxa‐2,11‐diazadodecane (pydado)] and N,S [1,12‐bis(2‐pyridyl)‐5,8‐dithia‐2,11‐diazadodecane (pydadt)] donor atoms have been synthesised as perchlorate salts and characterised by X‐ray crystallography and ligand‐field spectroscopy. In both complexes the Ni2+ ion is hexacoordinate. The cation [Ni(pydado)]2+ is pseudo‐octahedral with the two pyridyl groups in trans position; all Ni−N and Ni−O bond lengths are practically equivalent. In [Ni(pydadt)]2+ complex, however, the size of the thioether sulfur atoms imposes a C2v symmetry; the pyridyl groups and the sulfur atoms are in trans positions and all Ni−N bond lengths are equivalent. The comparison of these structures with those of octahedral cobalt, copper and zinc complexes with the same ligands shows that their configurations depend not only on the nature of the two central donor atoms of the ligand, but also on the nature of the metallic ion. In aqueous solution, the stability constants of the NiII chelates with these two ligands, determined by potentiometry, show the formation of [Ni(LH)]3+ and [NiL]2+ species in all cases. The chelating power of the pydadt ligand is slightly greater than that of pydado. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Long Range Metal‐Metal Interactions Along Fe−NC−Ru−CN−Fe Chains
Authors: Sheng Tianlu , Vahrenkamp Heinrich
Published: March 2004

Trinuclear complexes with linear FeII−NC−RuII−CN−FeII arrays were obtained by attachment of FeCp(dppe) units to the cyanoruthenium complexes trans‐[Ru(CN)2(Py)4] (Py = pyridine, 4‐methylpyridine, 4‐ethylpyridine) . From their cyclic voltammograms it can be concluded that there are long‐range metal−metal interactions between their external iron centers. Partial oxidation led to the isolation of the corresponding mixed‐valent FeII−NC−RuII−CN−FeIII complexes. For these the long range metal−metal interactions are evident from a broad MMCT band in the NIR spectra. The MMCT properties were quantified by an analysis using the Hush formalism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
(μ‐Methylene)bis(methylzirconocene): Preparation, Molecular Structure, and Thermal Disproportionation
Authors: Hogenbirk Marijke , Schat Gerrit , Akkerman Otto S. , Bickelhaupt Friedrich , Schottek Jörg , Albrecht Markus , Fröhlich Roland , Kehr Gerald , Erker Gerhard , Kooijman Huub , Spek Anthony L.
Published: March 2004

The title compound [(μ‐CH2)(ZrCp2Me)2] (4) was prepared by the reaction of [Cp2Zr(Cl)Me] (6) with CH2(MgBr)2 (5) or (CH2Mg)n (7). It had been expected that the carbon atom bridging the two zirconium atoms of 4 might be a candidate for a planar tetracoordinate carbon atom, but the X‐ray crystal structures of two different modifications (crystals 1 and 2) showed it to be non‐planar; however, the widened Zr−C−Zr angle of 132.7(1) and 134.0(3)°, respectively, and an unsymmetrical coordination of the central μ‐CH2 group (average: Zr1−CH2 2.225 Å, Zr2−CH2 2.242 Å) indicates a tendency towards planarity. While 4 is relatively stable in THF solution, it disproportionates in toluene solution to give the 1,3‐dizirconacyclobutane (Cp2ZrCH2)2 (8) and [Cp2ZrMe2] (9), especially in the presence of magnesium salts; a tentative mechanism is presented. Reaction of 4 with B(C6F5)3 yielded the methyl‐bridged cationic complex 17, which, on treatment with trityl chloride, was transformed into the corresponding chloro complex 18; the latter was characterized by an X‐ray crystal structure determination. With THF and tetrahydrothiophene, 17 formed the unsymmetrical adducts 19a and 19b, respectively; NMR spectroscopic data revealed dynamic symmetrization due to methyl‐group exchange at 280 and 213 K, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Towards 3‐D Spherical Self‐Assembly by Ternary Surfactant Combinations: The Case of Magnetite Nanoparticles
Authors: Hou Yanglong , Gao Song , Ohta Toshiaki , Kondoh Hiroshi
Published: March 2004

Here we report on a facile one‐step route to assemble magnetite nanoparticles into 3D‐spherical aggregates with an average diameter of 100 nm. The self‐assembly approach was achieved in a solvothermal reduction reaction with a ternary surfactant combination comprising trioctylphosphane oxide (TOPO), polyvinylpyrrolidone (PVP), and oleic acid as the “mortar”. Transmission electron microscopy (TEM) investigations indicated that the spherical aggregates were composed of magnetite nanoparticles. The mean size of the individual magnetite particles was estimated to be 6 nm, calculated by the Scherrer equation with the powder X‐ray diffraction (XRD) data. The formation mechanism of magnetite spheres can be attributed to the cooperation of the ternary surfactants described above. Magnetic measurements performed by a Quantum Design SQUID magnetometer on the nanoparticles exhibited superparamagnetic behavior above liquid‐nitrogen temperatures. Fourier‐transform infrared spectroscopy (FTIR), inductively coupled plasma‐atomic emission spectrometer (ICP‐AE) and X‐ray photoelectron spectroscopy (XPS) were also used in the characterization of the assembled magnetite spheres. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Supramolecular Host‐Guest Systems in Zeolites Prepared by Ship‐in‐a‐Bottle Synthesis
Authors: Corma Avelino , Garcia Hermenegildo
Published: March 2004

Zeolites have a microporous system defining large cavities interconnected by smaller windows. These cages can accommodate large molecules whose size, however, can be too big to cross the windows. The most important examples of these tridirectional zeolites are faujasites X and Y, but examples of other suitable zeolites are Beta, EMT and MCM‐22. The inclusion of large guests inside the cavities starts from smaller precursors that can diffuse through the zeolite pores and then react inside the cavities to form the target guest. This microreview discusses the special characterisation techniques necessary to study these systems, differentiating those that serve to assess the identity and purity of the guests from those that address the internal vs. external location of the guests with respect to the zeolite host. It is organized by grouping the examples of ship‐in‐a‐bottle synthesis according to the potential application of the system as catalysts, photocatalysts, sensors, in molecular machines, etc. Although proper credit is given to the pioneering reports on ship‐in‐a‐bottle synthesis, the emphasis is placed on the most recent examples of the literature covering up to mid 2003. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Supramolecular Host‐Guest Systems in Zeolites Prepared by Ship‐in‐a‐Bottle Synthesis (Eur. J. Inorg. Chem. 6/2004)
Authors: Corma Avelino , Garcia Hermenegildo
Published: March 2004

The cover picture shows the results of modelling the diffusion of phthalodinitrile through the zeolite pores. Once inside, phthalodinitrile reacts to form a large phthalocyanine guest that remains entrapped inside the zeolite cavity. The resultingzeolite−guest chemistry resembles at molecular level a ship in a bottle that is a typical souvenir in many harbour cities. The zeolite‐encapsulated guest shows many promising applications as discussed in the Microreview by A. Corma and H. Garcia on p. 1143 ff.
Bioactive constituents, flavors and aromas of virgin oils obtained by processing olives with a natural enzyme extract
Authors: Ranalli Alfonso , Lucera Lucia , Contento Stefania , Simone Nicola , Del Re Paolo
Published: March 2004

To enhance both virgin olive oil quality and yields, a natural enzyme extract (Bioliva) was used during processing of four Italian olive cultivars (Leccino, Caroleo, Dritta and Coratina) carried out with a percolation‐centrifugation extraction system. This biological formulation is essentially made up of natural enzyme species capable of degrading the major constituents of the vegetal cell membrane, such as pectin and cellulose. The oils of the second extraction (centrifuged oils), considered in this work, were fully characterized. The enzyme effects resulted in an enhanced incorporation of minor components (phenols, tocopherols, volatiles, carotenes, xanthophylls and chlorophylls) into the oil phase with consequent significant improvement of the analytical parameters related to typicality, flavor and shelflife. No significant modifications concerning triacylglycerols, fatty acids, and non‐glycerol compounds mainly related to genuineness were observed. A significant improvement of the oil outputs and the features of by‐products was also achieved. Another important outcome to be highlighted is the lower values concerning the emulsified fat, suspended solids, dry matter and COD (chemical oxygen demand) characterising the liquid effluent (olive juice).
Influence of oil conditioning on the permeate flux and cake properties during microfiltration of lampante olive oil
Authors: Hafidi Abdellatif , Pioch Daniel , Teyssier Marie‐Laure , Ajana Hamid
Published: March 2004

This work studies the deacidification of lampante virgin olive oil (acidity ranging from 2.15–4.65%) by microfiltration through alumina membrane. The effects of (i) the amount of absorbed water during the neutralization of the free fatty acids with various NaOH concentrations, and (ii) the acid pre‐treatment with phosphoric acid on permeate fluxes during microfiltration were studied. Physical properties of the cake (specific resistance and compressibility) were also investigated. The soap molecules are known to self assemble and form multilamellar vesicles with hundreds of bilayers entrapping water molecules between the polar groups. Swelling and deformability of such structures must be influenced by the amount of solubilized water. Our results show for all tested oils that a dilute NaOH solution (20%) allows the highest flux through the membrane, i.e. about 3‐fold the flux resulting from 40%‐NaOH treatment. The improvement of the initial fluxes reached approximately 300% in comparison with those obtained with more concentrated NaOH solutions, whereas the use of a more diluted solution (10% NaOH) caused a loss of separation efficiency. The addition of 0.1% (wt/wt) of phosphoric acid prior to neutralization results in further flux improvement especially at the beginning of filtration. The initial fluxes doubled when passing from 0–0.05% H3PO4 and then, in case of 20% NaOH to 0.1%. The average cake‐specific resistance was the highest in the case of neutralization with 30% NaOH and the lowest when coupling 0.1% H3PO4 pre‐treatment with 20% NaOH neutralization. In the latter case the cake showed a highly compressible behavior.
Oil extraction from almond, apricot and rice bran by three‐phase partitioning after ultrasonication
Authors: Sharma Aparna , Gupta Munishwar Nath
Published: March 2004

Three‐phase partitioning has been evaluated for extraction of oil from 3 different plant sources, namely almond, apricot and rice bran. After treatment of the slurries for 2, 4 and 6 min by ultrasonication followed by three‐phase partitioning, 87, 77 and 88% (wt/wt) oil was extracted within 1 h. The process required simultaneous addition of t‐butanol and ammonium sulphate to the slurries.
Effects of fish oil type, lipid antioxidants and presence of rapeseed oil on oxidative flavour stability of fish oil enriched milk
Authors: Let Mette B. , Jacobsen Charlotte , Meyer Anne S.
Published: March 2004

As a part of our ongoing experiments on optimization of the oxidative stability of fish oils in genuine food systems, this study investigated the oxidative deterioration of fish oil enriched milk emulsions during cold storage. The experimental data showed that addition of rapeseed oil to fish oil (1:1) prior to emulsification into milk significantly protected the emulsions against oxidative deterioration. Addition of propyl gallate and a citric acid ester to the fish oil prior to emulsification also protected the fish oil enriched milk during storage. Emulsions containing a rapeseed:fish oil mixture were oxidatively stable during 11 d at 2 °C. Thus, no additional inhibitory effect of the added antioxidants was observed. The peroxide value and concentrations of five selected volatiles derived from n‐3 PUFA degradation in rapeseed:fish oil mixture emulsions were not significantly different from the corresponding levels in neither the emulsion containing only rapeseed oil nor the milk. It is proposed that the tocopherols in rapeseed oil may be the protective factor. Three‐way chemometric exploratory data analysis was implemented in form of a parallel factor analysis (PARAFAC). The PARAFAC model provided an overview of the obtained data with significantly enhanced interpretability, and revealed information about groupings and correlations in our data.
Improving solvent‐free extraction of policosanol from rice bran by high‐intensity ultrasound treatment
Authors: Cravotto Giancarlo , Binello Arianna , Merizzi Gianfranco , Avogadro Milvio
Published: March 2004

Rice bran, a rich source of nutrients and pharmacologically active compounds, is currently discarded or used as livestock feed, only small amounts being earmarked for oil production. Oil extraction can be efficiently performed in 30 min under high‐intensity ultrasound either with hexane or without any organic solvent, using a basic aqueous solution instead. Under sonochemical conditions bran wax can also be hydrolyzed yielding policosanol (common name for a mixture of C24‐C34 linear saturated fatty alcohols). We suggest that wax, a waste of rice oil manufacture, should be exploited to recover its alcoholic moiety that is very rich in policosanol. Quantitative data on extraction and purification of policosanol are presented. Both the first bran fraction from rice polishing and the discarded wax from the manufacture of rice oil are convenient and profitable starting materials for the production of policosanol.
Determination of the oxidative stability of vegetable oils by Differential Scanning Calorimetry and Rancimat measurements
Authors: Kowalski Bolesław , Ratusz Katarzyna , Kowalska Dorota , Bekas Witold
Published: March 2004

Samples of vegetable oils were oxidized at isothermal conditions in the cell of a Pressure Differential Scanning Calorimeter (PDSC) and in the Methrom Rancimat apparatus. The PDSC and Rancimat experiments were carried out at a temperature in the range of 90–160 °C. From resulting PDSC exotherms their times to reach the peak maximum (τPDSC) were determined and used for the assessment of the oxidative stability of the samples. Similarly the measured Rancimat induction times (τRancimat) were used. As PDSC and Rancimat results were obtained at different temperatures the equations for temperature extrapolations of the τPDSC and τRancimat values have been proposed. Using the Arrhenius type correlation between induction times and temperature and activated complex theory the reaction rate constants, activation energies, activation enthalpies and activation entropies for oils oxidation have been calculated.
The effect of bidirectional flow on tidal channel planforms
Authors: Fagherazzi Sergio , Gabet Emmanuel J. , Furbish David Jon
Published: March 2004

Salt marsh tidal channels are highly sinuous. For this project, ﬁeld surveys and aerial photographs were used to characterize the planform of tidal channels at China Camp Marsh in the San Francisco Bay, California. To model the planform evolution, we assume that the topographic curvature of the channel centreline is a key element driving meander migration. Extraction of curvature data from a planimetric survey, however, presents certain problems because simple calculations based on equally distanced points on the channel axis produce numerical noise that pollutes the ﬁnal curvature data. We found that a spline interpolation and a polynomial ﬁt to the survey data provided us with a robust means of calculating channel curvature. The curvature calculations, combined with data from numerous cross‐sections along the tidal channel, were used to parameterize a computer model. With this model, based on recent theoretical work, the relationship between planform shape and meander migration as well as the consequences of bidirectional ﬂow on planform evolution have been investigated. Bank failure in vegetated salt marsh channels is characterized by slump blocks that persist in the channel for several years. It is therefore possible to identify reaches of active bank erosion and test model predictions. Our results suggest that the geometry and evolution of meanders at China Camp Marsh, California, reﬂect the ebb‐dominated regime. Copyright © 2004 John Wiley & Sons, Ltd.
Reconstructing the development of a gully in the Upper Kalaus basin, Stavropol region (southern Russia)
Authors: Belyaev V.R. , Wallbrink P.J. , Golosov V.N. , Murray A.S. , Sidorchuk A.Yu.
Published: March 2004

The Stavropol region of southern Russia is severely affected by human‐induced gully erosion. A lack of detailed information on the different stages of gully formation resulting from major agricultural expansion c. 100 years ago, is an obstacle for management and containment of these systems. In this study we combine measurements of particle‐bound radionuclides (137Cs, 210Pbex, 226Ra, 232Th and 40K) and classical geomorphology to investigate and reconstruct the different phases of development of a gully during the last c. 100 years. We believe the ﬁrst phase (1) involved an initial incision into the bottom of a small valley (catchment area c. 1 km2) about 100 years ago. A short period of rapid growth was followed by a longer stage of gully stabilization. Subsequent phases were: (2) the period 1954–1960 – re‐incision in the lower gully reach was initiated by a high‐magnitude rainfall event, and a substantial amount of sediment was delivered to the gully fan; (3) c. 1960–1986 – the knickpoint retreated slowly, sediment was redeposited nearby, and the fan surface became stable; (4) 1986–1987 – a dam was built in the gully mouth and breached shortly after construction following 2 days of high rainfall, and substantial sediment accumulated in the gully above the dam and below the spillway channel on the fan surface; (5) 1987–1993 – the knickpoint retreat continued and the lower fan surface was stable until 1993 when the last signiﬁcant runoff event overlayed it with c. 10 cm of fresh sediment. These detailed reconstructions of gully development stages allow the contribution of high‐magnitude events to gully growth and regional sediment delivery to be assessed. They further guide management actions to prevent such dam failures in the future. Copyright © 2004 John Wiley & Sons, Ltd.
Experimental investigation of the velocity of a sand cloud blowing over a sandy surface
Authors: Dong Zhibao , Liu Xiaoping , Wang Xunming , Li Fang , Zhao Aiguo
Published: March 2004

The velocity of a wind‐blown sand cloud is important for studying its kinetic energy, related erosion, and control measures. PDA (particle dynamics analyser) measurement technology is used in a wind tunnel to study the probability distribution of particle velocity, variations with height of the mean velocity and particle turbulence in a sand cloud blowing over a sandy surface. The results suggest that the probability distribution of the particle velocity in a blowing sand cloud is stochastic. The probability distribution of the downwind velocity complies with a Gaussian function, while that of the vertical velocity is greatly complicated by grain impact with the bed and particle–particle collisions in the air. The probability distribution of the vertical velocity of ﬁne particles (0·1–0·3 mm sands) can be expressed as a Lorentzian function while that of coarse particles (0·3–0·6 mm sands) cannot be expressed by a simple distribution function. The mean downwind velocity is generally one or two orders greater than the mean vertical velocity, but the particle turbulence in the vertical direction is at least two orders greater than that in the downwind direction. In general, the mean downwind velocity increases with height and free‐stream wind velocity, but decreases with grain size. The variation with height of the mean downwind velocity can be expressed by a power function. The particle turbulence of a blowing sand cloud in the downwind direction decreases with height. The variations with height of the mean velocity and particle turbulence in the vertical direction are very complex. It can be concluded that the velocity of a sand cloud blowing over a sandy surface is mainly inﬂuenced by wind velocity, grain impact with the bed and particle–particle collisions in the air. Wind velocity is the primary factor inﬂuencing the downwind velocity of a blowing sand cloud, while the grain impact with the bed and particle–particle collisions in the air are the primary factors responsible for the vertical velocity. Copyright © 2004 John Wiley & Sons, Ltd.
A hybrid method for size characterization of coarse subsurface fluvial sediments
Authors: Rice Stephen P. , Haschenburger Judith K.
Published: March 2004

This paper introduces and evaluates a novel method for ascertaining the grain‐size distribution of subsurface sediments that involves profoundly less sampling effort than standard methods. It is based on hybrid sampling principles previously applied to the construction of synthetic surface grain‐size distributions. The method is developed from an empirical demonstration of the approximate similarity of surface and subsurface grain‐size distributions when compared over a common range of sizes. Subsurface hybrid models are found to provide good facsimiles of grain‐size distributions deﬁned using standard criteria and to yield distribution percentiles with millimetre accuracy. The technique is presented as an expedient alternative to standard methods for large, perennial gravel‐bed rivers. As this is a new technique, prudent application is advised in lieu of further investigation. Copyright © 2004 John Wiley & Sons, Ltd.
Do designated market makers improve liquidity in open‐outcry futures markets?
Authors: Tse Yiuman , Zabotina Tatyana
Published: March 2004

On February 1, 2002, the Chicago Board of Trade appointed a designated market maker to enhance liquidity in
its 10‐year interest rate swap futures contract. This market‐making program is the first of its
kind in the open‐outcry futures industry. We find that introduction of the market maker has increased
volume and reduced transaction costs. The market maker has also enhanced the speed and the efficiency of price
discovery. Overall, the results suggest that the market‐making program is successful in improving
liquidity. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:479–502, 2004
Rational expectations and market efficiency in the U.S. live cattle futures market: The role of proprietary information
Authors: Schaefer Matthew P. , Myers Robert J. , Koontz Stephen R.
Published: March 2004

The role of proprietary information in forecasting and market efficiency in the U.S. live cattle futures
market is investigated. Using a unique proprietary data source collected by a private firm, we test whether the
initial estimates in the USDA Cattle on Feed Report and the Knight‐Ridder
pre‐release forecasts are unbiased and efficient forecasts of final revised USDA Cattle on Feed
Report numbers. We then use these results to test whether futures price movements are predictable based
on information in the proprietary data. We also test whether the initial estimates from the Cattle on
Feed Report have new information that moves prices once the information contained in the proprietary
data source has been taken into account. Results suggest that the information contained in the proprietary data
source does have statistically significant explanatory power for forecasting final revised Cattle on Feed
Report numbers and for predicting short‐term price movements of futures contracts. The results
are inconsistent with strong‐form market efficiency in the live cattle futures market. We also find that
the initial estimates in the Cattle on Feed Report still have new information that moves prices
even after accounting for the unique information in both the Knight‐Ridder pre‐release forecasts
and the proprietary data. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:429–451, 2004
Clustering in the futures market: Evidence from S&P 500 futures contracts
Authors: Schwartz Adam L. , Van Ness Bonnie F. , Van Ness Robert A.
Published: March 2004

We document trade price clustering in the futures markets. We find clustering at prices of x.00 and x.50 for
S&P 500 futures contracts. While trade price clustering is evident throughout time to maturity of these
contracts, there is a dramatic change when the S&P 500 futures contract is designated a front‐month
contract (decrease in clustering) and a back‐month contract (increase in clustering).
We find that trade price clustering is a positive function of volatility and a negative function of volume or open
interest. In addition, we find a high degree of clustering in the daily opening and closing prices, but a lower
degree of clustering in the settlement prices. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:413–428,
2004
A note on price futures versus revenue futures contracts
Authors: Lien Donald , Hennessy David A.
Published: March 2004

Here we consider the hedging roles of a price futures contract versus a revenue futures contract. In the
absence of idiosyncratic output risk, the revenue contract almost always dominates the price contract.
Idiosyncratic output risk provides conditions under which the price contract should dominate. When production
risk
is largely idiosyncratic, a producer with an anticipated long actuals position might combine a long revenue
futures position with a short price futures position. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark
24:503–512, 2004
An examination of the impact of macroeconomic news on the spot and futures treasuries markets
Authors: Simpson Marc W. , Ramchander Sanjay
Published: March 2004

In this study we analyze the reaction of daily cash and futures prices for several Treasury securities to the
release of U.S. macroeconomic news. Some important results are reported. First, consistent with the notion of
market integration, the futures market is found to be cointegrated with the corresponding cash market. Second, of
the 23 types of periodic macroeconomic announcements, 19 of them have a significant influence on either the cash or
futures prices. Most notably, surprises in nonfarm payroll and Treasury budget significantly influence the cash and
futures market across the entire maturity spectrum. Third, consistent with the Fisher and real activity hypotheses,
macroeconomic news that conveys higher inflation and/or economic growth has a negative influence on cash and
futures prices. Finally, hedging with Treasury futures appears to offer investors protection from
inflation‐related fluctuations in interest rates, but not against fluctuations arising due to variations in
real output. Some important policy implications of the results are offered. © 2004 Wiley Periodicals, Inc. Jrl
Fut Mark 24:453–478, 2004
Power of non‐parametric linkage analysis in mapping genes contributing to human longevity in long‐lived sib‐pairs
Authors: Tan Qihua , Zhao J. H. , Iachine I. , Hjelmborg J. , Vach W. , Vaupel J. W. , Christensen K. , Kruse T.A.
Published: March 2004

This report investigates the power issue in applying the non‐parametric linkage analysis of affected sib‐pairs (ASP) [Kruglyak and Lander, 1995: Am J Hum Genet 57:439–454] to localize genes that contribute to human longevity using long‐lived sib‐pairs. Data were simulated by introducing a recently developed statistical model for measuring marker‐longevity associations [Yashin et al., 1999: Am J Hum Genet 65:1178–1193], enabling direct power comparison between linkage and association approaches. The non‐parametric linkage (NPL) scores estimated in the region harboring the causal allele are evaluated to assess the statistical power for different genetic (allele frequency and risk) and heterogeneity parameters under various sampling schemes (age‐cut and sample size). Based on the genotype‐specific survival function, we derived a heritability calculation as an overall measurement for the effect of causal genes with different parameter settings so that the power can be compared for different modes (dominant, recessive) of inheritance. Our results show that the ASP approach is a powerful tool in mapping very strong effect genes, both dominant and recessive. To map a rare dominant genetic variation that reduces hazard of death by half, a large sample (above 600 pairs) with at least one extremely long‐lived (over age 99) sib in each pair is needed. Again, with large sample size and high age cut‐off, the method is able to localize recessive genes with relatively small effects, but the power is very limited in case of a dominant effect. Although the power issue may depend heavily on the true genetic nature in maintaining survival, our study suggests that results from small‐scale sib‐pair investigations should be referred with caution, given the complexity of human longevity. © 2004 Wiley‐Liss, Inc.
Properties of case/pseudocontrol analysis for genetic association studies: Effects of recombination, ascertainment, and multiple affected offspring
Authors: Cordell Heather J.
Published: March 2004

The case/pseudocontrol approach is a general framework for family‐based association analysis, incorporating several previously proposed methods such as the transmission/disequilibrium test and log‐linear modelling of parent‐of‐origin effects. In this report, I examine the properties of methods based on a case/pseudocontrol approach when applied to a linked marker rather than (or in addition to) the true disease locus or loci, and when applied to sibships that have been ascertained on, or that may simply contain, multiple affected sibs. Through simulations and analytical calculations, I show that the expected values of the observed relative risk parameters (estimating quantities such as effects due to a child's own genotype, maternal genotype, and parent‐of‐origin) depend crucially on the ascertainment scheme used, as well as on whether there is non‐negligible recombination between the true disease locus and the locus under study. In the presence of either recombination or ascertainment on multiple affected offspring, methods based on conditioning on parental genotypes are shown to give unbiased genotype relative risk estimates at the true disease locus (or loci) but biased estimates of population genotype relative risks at a linked marker, suggesting that the resulting estimates may be misleading when used to predict the power of future studies. Methods that allow for exchangeability of parental genotypes are shown (in the presence of either recombination or ascertainment on multiple affected offspring) to produce false‐positive evidence of maternal genotype effects when there are true parent‐of‐origin or mother‐child interaction effects, even when analyzing the true locus. These results suggest that care should be taken in both the interpretation and application of parameter estimates obtained from family‐based genetic association studies. © 2004 Wiley‐Liss, Inc.