bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth, structure, and superconducting properties of Bi2Sr2Ca2Cu3O10 and (Bi,Pb)2Sr2Ca2Cu3O10‐y crystals
Authors: Giannini E. , Garnier V. , Clayton N. , Musolino N. , Gladyshevskii R. , Flükiger R.
Published: September 2004

Large and high‐quality single crystals of both Pb‐free and Pb‐doped high temperature superconducting compounds (Bi1‐xPbx)2Sr2Ca2Cu3O10‐y (x = 0 and 0.3) were grown by means of a newly developed “Vapour‐Assisted Travelling Floating Zone” technique (VA‐TSFZ). This modified zone‐melting technique was realised in an image furnace and allowed for the first time to grow Pb‐doped crystals by compensating for the Pb losses occurring at high temperature. Crystals up to 3×2×0.1 mm3 were successfully grown. Post‐annealing under high pressure of O2 (up to 10 MPa at T = 500°C) was undertaken to enhance Tc and improve the homogeneity of the crystals. Structural characterisation was performed by single‐crystal X‐ray diffraction (XRD) and the structure of the 3‐layer Bi‐based superconducting compound was refined for the first time. Structure refinement showed an incommensurate superlattice in the Pb‐free crystals. The space group is orthorhombic, A2aa, with cell parameters a = 27.105(4) Å, b = 5.4133(6) Å and c = 37.009(7) Å. Superconducting studies were carried out by A.C. and D.C. magnetic measurements. Very sharp superconducting transitions were obtained in both kinds of crystals (ΔTc ≤ 1 K). In optimally doped Pb‐free crystals, critical temperatures up to 111 K were measured. Magnetic critical current densities of 2�105 A/cm2 were measured at T = 30 K and μ0H = 0 T. A weak second peak in the magnetisation loops was observed in the temperature range 40‐50 K above which the vortex lattice becomes entangled. We have measured a portion of the irreversibility line (0.1‐5 Tesla) and fitted the expression for the melting of a vortex glass in a 2D fluctuation regime to the experimental data. Measurements of the lower critical field allowed to obtain the dependence of the penetration depth on temperature: the linear dependence of λ(T) for T < 30 K is consistent with d‐wave superconductivity in Bi‐2223. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of Er incorporation on GaSb substrates by diffusion
Authors: Ruiz C. M. , Plaza J. L. , Bermúdez V. , Diéguez E.
Published: September 2004

On this work, two different ways of introducing Er ions to GaSb crystals, one bulk doped and the other Er diffused are compared in order to obtain Er luminescence on GaSb matrix. For this objetive, photoluminescence measurements indicate that there is Er luminescence on the diffused sample, while on the bulk doped, not only there is no Er activation, but crystal quality decreases severally. Surface analysis of diffused sample shows the presence of holes all over the surface. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanoelectronic single‐electron transistor circuits and architectures
Authors: Gerousis C. P. , Goodnick S. M. , Porod W.
Published: September 2004

Single‐electron tunneling (SET) devices have been proposed as one promising candidate for future nanoelectronic integrated circuits. SETs have appealing properties for implementing ultra‐dense and complex signal and image processing systems. The potential for very dense arrays of SET transistors makes them attractive for the realization of cellular non‐linear network (CNN) circuits, where locally‐connected cells may alleviate the interconnect problem facing conventional architectures as they scale.

Herein, we investigate the use of nanoelectronic structures in CMOS‐type digital circuits and in analog CNN architectures for potential application in future high‐density and low‐power CMOS‐nanodevice hybrid circuits. We first present an overview of the operation of the SET transistor and simulation of SET circuits. We then discuss a programmable CMOS‐type SET logic circuit based on a summing‐node‐inverter structure, followed by simple linear and 2‐d SET‐CNN architectures using the SET inverter topology as the basis for the non‐linear transfer characteristics required of individual CNN elements. The simple SET‐CNN cell acts as a summing node that is capacitively coupled to the inputs and outputs of nearest neighbour cells. Monte Carlo simulation results are then used to show CNN‐like behaviour in attempting to realize different functionality such as shadowing, pattern forming, and horizontal‐line detection. Within the context of these simple architectures, we discuss the speed and signal delay in SET non‐linear circuits, and calculate the approximate power dissipation in a SET network. Copyright © 2004 John Wiley & Sons, Ltd.
Surface plasmon waves in nanoelectronic circuits
Authors: Csurgay Árpád I. , Porod Wolfgang
Published: September 2004

Plasma dynamics in nanoscale metal‐dielectric structures is reviewed, and circuit models for potential plasma wave nanodevices and circuits are developed. Circuit representations for surface‐plasmon waveguides, nanoantennas, and for surface plasmon generators based on attenuated total reflection (ATR), are presented. In metal–insulator–metal (MIM) structures tunnelling also excites surface plasmon waves, and the equivalent circuit introduced in this paper helps the design of circuits exploiting surface plasmon waves. These nanoelectronic circuits might have an impact on the future of terahertz and infrared electronics. Copyright © 2004 John Wiley & Sons, Ltd.
Basic concepts of quantum systems versus classical networks
Authors: Civalleri Pier Paolo , Gilli Marco , Bonnin Michele
Published: September 2004

The paper is intended to establish a conceptual bridge between Classical Network Theory and Quantum Mechanics. The concept of time‐reversal symmetry is extended from Quantum Mechanics to Network Theory (in the state equations description), while concepts of passivity and losslessness are extended from Network Theory to Quantum Mechanics. Copyright © 2004 John Wiley & Sons, Ltd.
Nanoantennas for uncooled, double‐band, CMOS compatible, high‐speed infrared sensors
Authors: Matyi Gábor
Published: September 2004

Nanoantennas for double‐band uncooled sensors are proposed for infrared focal plane arrays (FPA). Metal‐oxide‐metal tunnel diodes integrated with the nanoantennas are square‐law detectors for currents induced in the antennas by incident infrared radiation. The sensors that operate in the long‐wave infrared band are CMOS compatible and facilitate high‐speed processing exceeding 1000 frames per second. Double‐band sensors are proposed for each pixel of the FPA. The double‐band character of the sensor's responsivity is insured by the design of the antenna geometry. The frequency dependence of the insulator material is taken into account. Simulations of the proposed design are promising. Copyright © 2004 John Wiley & Sons, Ltd.
Pulsed dc Magnetron Discharges and their Utilization in Plasma Surface Engineering
Authors: Vlček J. , Pajdarová A. D. , Musil J.
Published: September 2004

Fundamental aspects of magnetron operation in two types of practically interesting discharges, i.e. in highpower unipolar pulsed dc magnetron discharges for ionized high‐rate sputtering and in asymmetric bipolar pulsed dc magnetron discharges for reactive sputtering, were investigated on the basis of time‐resolved plasma diagnostics. We present the results obtained using time‐resolved optical emission spectroscopy and time‐ and energy‐resolved mass spectroscopy in high‐power unipolar pulsed dc magnetron discharges at a repetition frequency of 1 kHz, an argon pressure of 1 Pa and an average target power loading in a pulse up to 500 W/cm2. The main aim was to study complex ionization mechanisms of sputtered Cu atoms and working gas (Ar) atoms, and to characterize energy distributions of Cu+ and Ar+ ions and their fractions in ion fluxes to a substrate during pulses. Some results achieved with a grooved target at the frequencies up to 50 kHz are discussed. We report also on the results obtained using energy‐resolved mass spectroscopy and time‐resolved Langmuir probe measurements in asymmetric bipolar pulsed dc magnetron discharges at repetition frequencies of 100 kHz and 350 kHz, an argon pressure of 0.53 Pa and a mean discharge power of 300W. They explain a complex correlation between the pulsed plasma dynamics and the enhanced ion bombardment of growing films in these discharges. Some new development trends in the field of the dual pulsed dc magnetron sputtering are outlined. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atomic Layer Deposition of ZrO2 Thin Films Using Dichlorobis[bis‐(trimethylsilyl)amido]zirconium and Water
Authors: Nam W.‐H. , Rhee S.‐W.
Published: September 2004

A new zirconium precursor, (ZrCl2[N(SiMe3)2]2), and H2O oxidant were used to deposit ZrO2 films on a Si substrate, for alternative gate dielectrics, via atomic layer deposition (ALD) in the temperature range 150–350 °C. The film growth showed the self‐limiting characteristic of ALD, with a maximum growth rate of 1.6 Å per cycle at 175 °C. The compositions of as‐deposited films were analyzed by Rutherford backscattering spectroscopy (RBS), X‐ray photoelectron spectroscopy (XPS), and secondary ion mass spectroscopy (SIMS), and it was found that the amount of silicon in ZrO2 films was uniformly distributed throughout the film in the range of 1.1 at.‐% to 5.4 at.‐% as the deposition temperature was increased. After rapid thermal annealing in an Ar atmosphere at 700–900 °C, the amorphous as‐deposited film was crystallized mainly in the cubic phase, and no significant change in surface morphology was observed.
A Simple Index to Restrain Abnormal Protrusions in Films Fabricated Using CVD under Diffusion‐Limited Conditions
Authors: Kajikawa Y. , Noda S. , Komiyama H.
Published: September 2004

Cauliflower‐like protrusions formed in CVD processes under diffusion‐limited conditions have been studied both experimentally and theoretically. Both approaches indicate that the difference in diffusion fluxes to the film and to the protrusions controls the growth of such protrusions. However, direct comparisons of these two approaches have never been done, probably due to the complexity of the theoretical models. To simplify model protrusion growth, we developed a one‐dimensional (1D) analytical model by hypothesizing the diffusion of growth species in the boundary layer above a growing film. Based on this model, we propose a non‐dimensional quantity, ksf/D, as an index of protrusion growth (D is the diffusion coefficient of the growth species, ks is the surface reaction‐rate coefficient, and f is film thickness). This index represents more directly the protrusion growth than does the previously proposed index, the Damköhler number, Da = ksδ/D, where δ is boundary layer thickness. To obtain smooth, protrusion‐free films, D/ks should be kept larger than the desired film thickness. By controlling the process conditions to satisfy this index, we successfully fabricated protrusion‐free films with SiC deposition from dichlorodimethylsilane (DDS).
Facile Synthesis and Characterization of New β‐Diketonate Silver Complexes. Single‐Crystal Structures of (1,1,1,5,5,5‐Hexafluoro‐2,4‐pentadionato)(2,2′‐bipyridine)silver(I) and (1,1,1,5,5,5‐Hexafluoro‐2,4‐pentadionato)(N,N,N′,N′‐tetramethylethylenediamine)silver(I) and Their Use as MOCVD Precursors for Silver Films
Authors: Zanotto L. , Benetollo F. , Natali M. , Rossetto G. , Zanella P. , Kaciulis S. , Mezzi A.
Published: September 2004

Thin film depositions of metallic silver were performed using metal–organic (MO) CVD on glass substrates using, as precursors, the two new compounds (1,1,1,5,5,5‐hexafluoro‐2,4‐pentanedionato)(2,2′‐bipyridine)silver(I), [Ag(hfac)(bipy)] (1), and (1,1,1,5,5,5‐hexafluoro‐2,4‐pentanedionato)(N,N,N′,N′‐tetramethylethylenediamine)silver(I), [Ag(hfac)(tmeda)] (2). Both silver compounds were characterized by single‐crystal X‐ray diffraction (XRD) measurements, indicating that 1 exists as a dimeric species, and 2 as polymeric chains. The films were analyzed by XRD, X‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM), revealing a high crystallinity and fairly good quality with little carbon and oxygen contamination when using the tetramethylethylenediamine derivative.
CVD of Nanophasic (Zn, Cd)S Thin Films: From Multi‐Layers to Solid Solutions
Authors: Barreca D. , Gasparotto A. , Maragno C. , Tondello E. , Sada C.
Published: September 2004

Nanostructured ZnxCd1 – xS (0 ≤ x ≤ 1) thin films were synthesized by CVD on SiO2 substrates using M(O‐iPrXan)2 (M = Zn,Cd; O‐iPrXan = S2COCH(CH3)2) as precursor compounds. The method of preparation used consisted in the sequential deposition of single‐phase MS coatings (M = Zn,Cd) at 300 °C in a N2 flow, followed by ex‐situ annealing in an inert atmosphere at various temperatures in the range 400–700 °C. The obtained specimens were thoroughly characterized before and after thermal treatments, paying particular attention to their structure, composition, morphology, and optical properties. Annealing in N2 at 600 °C for 3 h resulted in the formation of a homogeneous ZnxCd1 – xS solid solution. Lower temperatures did not produce a uniform sample composition, while more severe annealing conditions induced CdS sublimation. Moreover, a compositional control of the ZnxCd1 – xS ternary phase could be achieved by varying the ZnS overlayer deposition time.

Irrespective of the annealing conditions, all the obtained films were contaminant‐free and nanophasic (∅︁ ≈25 nm), and possessed a hexagonal crystal structure the lattice parameters of which decreased linearly with increasing zinc molar fraction. A parallel evolution of optical absorption spectra was also observed. In the present paper, the interrelations between film properties and processing conditions are investigated, focusing particularly on the (Zn,Cd)S evolution to ZnxCd1 – xS solid solutions.
Early language development in children with a genetic risk of dyslexia
Authors: van Alphen Petra , de Bree Elise , Gerrits Ellen , de Jong Jan , Wilsenach Carien , Wijnen Frank
Published: September 2004

We report on a prospective longitudinal research programme exploring the connection between language acquisition deficits and dyslexia. The language development profile of children at‐risk for dyslexia is compared to that of age‐matched controls as well as of children who have been diagnosed with specific language impairment (SLI). The experiments described concern the perception and production of grammatical morphology, categorical perception of speech sounds, phonological processing (non‐word repetition), mispronunciation detection, and rhyme detection. The results of each of these indicate that the at‐risk children as a group underperform in comparison to the controls, and that, in most cases, they approach the SLI group. It can be concluded that dyslexia most likely has precursors in language development, also in domains other than those traditionally considered conditional for the acquisition of literacy skills. The dyslexia‐SLI connection awaits further, particularly qualitative, analyses. Copyright © 2004 John Wiley & Sons, Ltd.
Prevalence of persistent primary reflexes and motor problems in children with reading difficulties
Authors: McPhillips M. , Sheehy N.
Published: September 2004

It has been shown that some children with reading difficulties have underlying developmental delay and that this may be related to the persistence of primary reflexes. This study investigated the prevalence of persistent primary reflexes in the ordinary primary school population and how this related to other cognitive and social factors. Three groups of 41 children were drawn from a representative, cross‐sectional sample of 409 children (aged 9–10 years) attending 11 ordinary primary schools in N. Ireland. The three groups represented the bottom, middle and top 10% respectively of readers from the total sample population. The relative persistence (on a scale of 0 to 4) of the Asymmetrical Tonic Neck Reflex (ATNR) and the prevalence of motor difficulties were assessed for these 3 groups. The rôle of 5 predictor variables (verbal IQ, social deprivation, sex, month of birth and religious affiliation) in determining the reading level of the total sample was also investigated. It was found that the lowest reading group had a significantly higher mean level of ATNR (1.56 [95% CI 1.22–1.90]) compared with the middle reading group (0.56 [0.22–0.90]) and the top reading group (0.59 [0.25–0.92]). 17% of children in the lowest reading group had extremely high levels of the ATNR while 24% showed no presence of ATNR. This contrasted with 0% and 66%, respectively for both middle and top reading groups. It was also found that there was a significant difference between the lowest reading group and the top reading group on a standardised test of motor ability. Furthermore, there was evidence that ATNR persistence but not motor ability was associated with the sex of the child with boys, in particular, at risk. There was no evidence that ATNR persistence or motor ability was significantly associated with social deprivation. It was also found that there were no significant differences between dyslexic and non‐dyslexic children with reading difficulties in motor (including balance) performance. This study highlights the high levels of primary reflex persistence in children with reading difficulties and it provides further evidence of the association between reading difficulties and movement difficulties in young children. However, while the implications for intervention are discussed, it is stressed that the persistence of primary reflexes cannot be used as a causal model for reading difficulties, including dyslexia. Copyright © 2004 John Wiley & Sons, Ltd.
Coordination Chemistry and Asymmetric Catalysis with a Chiral Diphosphonite
Authors: van der Vlugt Jarl Ivar , Paulusse Jos M. J. , Zijp Eric J. , Tijmensen Jason A. , Mills Allison M. , Spek Anthony L. , Claver Carmen , Vogt Dieter
Published: September 2004

The improved synthesis of the chiral diphosphonite, XantBino (1), based on a xanthene backbone and bearing chiral binaphthyl groups on both P‐atoms is described together with its PdII and RhI complexes. The 31P NMR spectra of both complexes point out that the two phosphorus atoms are chemically inequivalent. The complex cis‐[PdCl2(1)] (2) is structurally characterized by NMR spectroscopy and X‐ray crystallography. The molecular structure reveals an unusually small bite angle for this member of the xantphos family of only 100°. The rhodium‐catalyzed asymmetric hydroformylation of styrene and vinyl acetate as well as the asymmetric hydrogenation of methyl (Z)‐2‐acetamidocinnamate, applying this chiral diphosphonite 1, are described. Low enantiomeric excesses are obtained in the asymmetric hydroformylation, while use of the catalyst precursor [Rh(cod)(1)]BF4 (3) results in a promising enantiomeric excess in the Rh‐catalyzed asymmetric hydrogenation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Palladium Complexes with Chiral Diphospholane Ligands: Comparative Catalytic Properties and Analysis of (η3‐Allyl)palladium Species
Authors: Malaisé Grégory , Ramdeehul Shailesh , Osborn John A. , Barloy Laurent , Kyritsakas Nathalie , Graff Roland
Published: September 2004

The chiral diphospholane ligands Duphos (1) and Duxantphos (2), which can be differentiated by their bite angle, were applied to palladium‐catalysed asymmetric reactions, essentially allylic alkylations with symmetrically (3a−d) or unsymmetrically (5a,b) substituted allylic acetates as substrates. The most interesting results were found with the first series of substrates in which 2 was more reactive and/or selective than 1. The model complexes of the catalytic intermediates [Pd{(S,S)‐1}(η3‐cyclohexenyl)](BF4) (10) and exo‐[Pd{(R,R)‐2}(η3‐cyclohexenyl)](SbF6) (11) could be characterised by X‐ray crystallography. 1H and 31P NMR spectroscopic analyses of [Pd{(R,R)‐2}(η3‐diphenylallyl)](SbF6) (12) and [Pd{(R,R)‐2}(η3‐allyl)](SbF6) (13) revealed the presence of exchanging isomers in solution. Structural data provided by these techniques combined with the preferential rotation model led to a satisfactory interpretation of the catalytic allylic alkylation results. It appears that the bite angle plays a crucial role in the positioning of the proximal methyl groups, which determines the distribution of allyl isomeric intermediates and the balance between clockwise and anticlockwise rotations in the enantioselective step. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Cα‐Deprotonated Iminophosphorane Ph2P(CH2Py)(NSiMe3) as an N,N‐Chelating Ligand for Iron and Zinc
Authors: Murso Alexander , Stalke Dietmar
Published: September 2004

The iminophosphorane Ph2P(CH2Py)(NSiMe3) (Py = NC5H4) is deprotonated at the Cα‐position in a reaction with [M{N(SiMe3)2}2] (M = Fe2+, Zn2+) to give metallaspirocycles in which the metal cations are N,N‐chelated by the ring‐ and imino‐nitrogen atoms of both monoanionic ligands. The molecular structures of [M{Ph2P(CHPy)(NSiMe3)}2] [M = Fe (1), Zn (2)] are discussed and general trends in the bonding of the [Ph2P(CHPy)(NSiMe3)]− anion on metal coordination are deduced. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis, Structures and Reactivity of Mono‐ and Diborylacetylenes
Authors: Goswami Avijit , Pritzkow Hans , Rominger Frank , Siebert Walter
Published: September 2004

The reaction of [bis(diisopropylamino)boryl]acetylene with 2 equiv. of HCl and 1 equiv. of dithiocatechol or 2‐hydroxythiophenol yields the corresponding monoborylacetylenes 1 and 2, respectively. Diborylacetylenes 3 and 4 are obtained from the reactions of bis(trimethylstannyl)acetylene with 2 equiv. of bromoboranes. Treatment of chlorobis(diisopropylamino)borane with LiC≡C−EMe3 (E = C, Si) leads to the corresponding element‐substituted [bis(diisopropylamino)boryl]acetylenes 5a,b. The syntheses of monoborylacetylenes 6a,b−8a,b are achieved by the reaction of 5a,b with 2 equiv. of HCl and 1 equiv. of catechol, dithiocatechol or 2‐hydroxythiophenol, respectively. Stoichiometric amounts of [CpCo(CO)2] react with 1−4 in refluxing toluene to give the corresponding (η4‐cyclobutadiene)cobalt complexes 9−12. Analogous isomeric mixtures of (η4‐cyclobutadiene)cobalt complexes 13a/13a′−15a/15a′ are obtained from 1‐tert‐butyl‐2‐borylacetylenes 6a−8a and [CpCo(C2H4)2], whereas isomeric mixtures of (η4‐cyclohexatriene)(η5‐cyclopentadienyl)cobalt complexes 13b/13b′−15b/15b′ are formed with 1‐boryl‐2‐silylacetylenes 6b−8b under similar conditions. Hydrolysis of 13a−15a yields the (η4‐1,3‐di‐tert‐butylcyclobutadiene)cobalt complex 16. Catalytic trimerizations of mono‐ (1, 2) and diborylacetylenes (3, 4) with Co2(CO)8 lead to isomeric mixtures of triboryl‐ (17/17′, 18/18′) and hexaborylbenzene derivatives (19, 20), respectively. The new compounds are characterized by NMR spectroscopy and mass spectrometry as well as by X‐ray structure analyses for 1b, 5b, 6b, 14a, 15a and 16. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Isolation of an Intermediate during the Decomposition of a Tetragold‐Phosphane Complex
Authors: Biricik Nermin , Fei Zhaofu , Scopelliti Rosario , Dyson Paul J.
Published: September 2004

Reaction of the diphosphanylamine 2,6‐{(Ph2P)2N}2C5H3N with four equivalents of Au(tht)Cl (tht = tetrahydrothiophene) affords the tetragold complex 2,6‐{(ClAuPh2P)2N}2C5H3N in high yield. Decomposition of the tetragold compound results in the formation of the digold complex 2,6‐{(ClAuPh2P)HN}2C5H3N and colloidal gold. A trigold intermediate, which contains a Au−Au interaction [2.9886(5) Å] has been isolated, and while ultimately unstable, it is thought to be partially stabilised by virtue of the aurophilic nature of gold. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Nonbridging and Monodentate Carboxylate Coordination of Calcium(2+) Through the Use of Intramolecular Hydrogen Bonding in a New Sterically Hindered Carboxylate Ligand
Authors: Crane Jonathan D. , Moreton David J. , Rogerson Eleanor
Published: September 2004

The sterically hindered carboxylate ligand 2,6‐bis(2,2‐dimethylpropionylamino)benzoic acid (HL) has been prepared. The two intramolecular hydrogen bonds in HL are exploited to restrict the corresponding carboxylate anion (L−) to nonbridging coordination and to preorganise its sterically bulky substituents proximal to the first and second coordination sphere of the bound metal ion. The crystal structures of the ligand anion as the ammonium salt [NH4][L] and the distorted octahedral calcium complex CaL2(H2O)2, in which L− binds to the calcium(2+) ion in a monodentate, nonbridging mode, are described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis, Crystal Structure and Biological Characterization of a Novel Palladium(II) Complex with a Coumarin‐Derived Ligand
Authors: Budzisz Elzbieta , Keppler Bernhard K. , Giester Gerald , Wozniczka Magdalena , Kufelnicki Aleksander , Nawrot Barbara
Published: September 2004

Methyl 2‐methyl‐4‐oxo‐4H‐chromene‐3‐carboxylate (1) was treated with 25% aqueous ammonia to give 3‐(1‐aminoethylidene)‐2H‐chromene‐2,4(3H)‐dione (2). Compound 2 was used as a ligand for the formation of a palladium(II) complex. The structures of the ligand and its palladium complex 3 were determined by IR and 1H NMR spectroscopy, FAB mass spectrometry and elemental analysis. The single‐crystal X‐ray structure of 3 was also solved. Ligand 2 in 20% dioxane solution shows two protonation constants — log β11 = 4.28 ± 0.01 and log β12 = 7.66 ± 0.03. In complex 3 two ligand molecules chelate to the Pd ion through their N and O donors, giving a four‐coordinate PdII center with a cis‐N2O2 donor set. The coordination geometry at PdII is square‐planar with typical values for the distances from the Pd atom to the coordinated atoms. The cytotoxicity of compound 3 was determined on three cancer cell lines. IC50 values of 9.7, 7.8 and 7.8 nM were found for A546, HeLa and K562 cells, respectively, which is notably lower than carboplatin, which shows corresponding IC50 values of 105.98, 73.49 and 60.92 μM. Double‐stranded DNA treated with 3 shows a significant increase in the Δϵ value in the CD spectra, as well as a lower electrophoretic mobility than parent DNA. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Influence of water content of the pulp on the extraction and the physicochemical properties of Canarium schweinfurthii oil
Authors: Tchiégang Clergé , Leudeu Bertille Carine Tchankou , Kapseu César , Fomethe Anaclete , Parmentier Michel
Published: September 2004

With the aim of contributing to the valorization of the Canarium schweinfurthii Engl. fruit pulp, through the extraction of its oil, we have studied the influence of the Canarium pulp's water content after drying at 45 °C on the yield of extraction using hexane. Furthermore we studied the physicochemical properties of the oil. It was observed that the oil's extraction yield is significantly influenced (p <0.01) by water content of the pulp. Maximum extraction yield (30.6 g fat/100 g) is obtained at a moisture content of 6.3%. The acid, saponification and peroxide values of the oils obtained were significantly influenced (p <0.05) by the humidity. The maximum acid values of 8.88 corresponded to a moisture content of 17.5%. Likewise, the saponification value showed a maximum of 154.1 for humidity content of 43.3% at the beginning of the drying step. The pulp oil's peroxide value initially at 3.7 meqO2/kg increased progressively until attaining 51.0 O2/kg at the end of drying. The iodine value was not influenced by humidity. A moisture content of 7.7% has been determined as the optimal value for optimizing both oil extraction yield and physicochemical property of the oil obtained.
Modelling lipase‐catalysed transesterification of fats containing n‐3 fatty acids monitored by their solid fat content
Authors: Nascimento Ana C. , Tecelão Carla S. R. , Gusmão José H. , da Fonseca M. Manuela R. , Ferreira‐Dias Suzana
Published: September 2004

Transesterification of fat blends rich in n‐3 polyunsaturated fatty acids (n‐3 PUFA), catalysed by a commercial immobilised thermostable lipase from Thermomyces lanuginosa, was carried out batch‐wise. Experiments were performed, following central composite rotatable designs (CCRDs) as a function of reaction time, temperature and media formulation. Mixtures of palm stearin, palm kernel oil and a commercial concentrate of triacylglycerols rich in n‐3 PUFA (“EPAX 2050TG” in CCRD‐1 and “EPAX 4510TG” in CCRD‐2) were used. The time‐course of transesterification was indirectly followed by the solid fat content (SFC) values of the blend at 10 °C, 20 °C, 30 °C and 35 °C.

A decrease in all SFC values of the blends at 10 °C, 20 °C, 30 °C and 35°C was observed upon transesterification. The SFC10 °C and SFC20 °C of transesterified blends varied between 18 and 48 and SFC35 °C between 6 and 24. These values fulfil the technological requirements for the production of margarines.

Under our conditions, lipid oxidation may be neglected. However, the accumulation up to 8.3% free fatty acids in reaction media is a problem to overcome.

The development of response surface models, describing both the final SFC value and the SFC decrease, will allow predicting results for novel proportions of fats and oils and/or a novel combination time‐temperature.
New dimensions in edible oil and fat analysis
Authors: Janssen Hans Gerd
Published: September 2004

No abstracts.
Lithiation of 2‐Aryl‐2‐(chloroaryl)‐1,3‐dioxolanes and Its Application in the Synthesis of New ortho‐Functionalized Benzophenone Derivatives
Authors: Lukács Gyula , Porcs‐Makkay Márta , Simig Gyula
Published: September 2004

2‐Aryl‐2‐(chloroaryl)‐1,3‐dioxolanes 4 were lithiated ortho to the ketal group of the chloroaryl ring by treatment with butyllithium in THF between −78 and 0 °C. The site selectivity of some of the deprotonation reactions was rationalized by the long‐range effect of the 4‐chloro substituent. The lithio species thus generated were treated with various electrophiles to give ortho‐functionalized benzophenone derivatives. Intramolecular competition between the aryl rings was observed in the lithiation of 2‐(4‐chlorophenyl)‐2‐(4‐fluorophenyl)‐1,3‐dioxolane (4s). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Titanium Carbide Thin‐Film Electrodes: Characterization and Evaluation as Working Electrodes
Authors: Lupu Alina , Compagnone Dario , Orlanducci Silvia , Terranova Maria Letizia , Magearu Vasile , Palleschi Giuseppe
Published: September 2004

Titanium carbide (TiC) polycrystalline thin films, obtained by a hybrid chemical vapor deposition/powder flowing technique, were characterized and used to assemble working electrodes. The potential window and the electrochemistry of standard redox couples ([Ru(NH3)6]3+, [Fe(CN)6]3−) have been investigated in cyclic voltammetry, demonstrating a behavior similar to glassy carbon electrodes. The quinone (Q)/hydroquinone(H2Q) redox couple presented an interesting quasireversible behavior(Ep=0.07 mV) , confirmed also for other quinones.
Selective Detection of Dopamine and Its Metabolite, DOPAC, in the Presence of Ascorbic Acid Using Diamond Electrode Modified by the Polymer Film
Authors: Roy Protiva Rani , Saha Madhu Sudan , Okajima Takeyoshi , Park Soo‐Gil , Fujishima Akira , Ohsaka Takeo
Published: September 2004

The surface of boron‐doped diamond (BDD) electrode is modified by the polymer film for the first time. The cationic polymer film of N,N‐dimethylaniline (DMA) is electrochemically deposited on BDD electrode surface. This polymer (PDMA) film‐coated BDD electrode is used as a sensor which selectively detect dopamine (DA) in the presence of ascorbic acid (AA). This electrode also can detect both DA and its metabolite, 3,4‐dihydroxy phenyl acetic acid (DOPAC) in the presence of AA in the range of the physiological concentrations of these species. Favorable ionic interaction (i.e., electrostatic attraction) between the PDMA film and AA or DOPAC lowers their oxidation potentials and enhances the current response for AA and DOPAC compared to that at the bare electrode. The PDMA film also shows a hydrophobic interaction with DA and DOPAC. In cyclic voltammetric measurements, the PDMA film‐coated electrode can successfully separate the oxidation potentials for AA and DA coexisting in the same solution and the separation is about 200 mV. AA oxidizes at more negative potential than DA. In square‐wave voltammetry, the sensitivity of the PDMA film‐coated BDD electrode for DA in the presence of higher concentration of AA is higher than that of the PDMA film‐coated glassy carbon electrode. The hydrodynamic amperometric experiments confirm that the oxidation of AA is not affected by the oxidized product of DA and vice versa. So, unlike the bare electrode the catalytic oxidation of AA by the oxidized DA is eliminated at the PDMA film‐coated BDD electrode. The sensitivities of the modified electrode for AA, DA and DOPAC, which are present in the same solution with their physiological concentration ratios, are calculated to be 0.070, 0.363 and 0.084 μA μM−1, respectively. The modified electrode exhibits a stable and sensitive response to DA.
Biomimetic Electroreduction of O2 by Hemoglobin in a Surfactant Film: Preliminary Electrochemical Impedance Spectroscopy Insight
Authors: Mimica Danica , Ringuedé Armelle , Agurto Claudio , Bedioui Fethi , Zagal José
Published: September 2004

We report in this study on the direct electron transfer for hemoglobin (Hb) entrapped in cationic didodecyldimethylammonium bromide (DDAB) surfactant films cast on vitreous‐carbon electrodes, in neutral aqueous solution. This was achieved by using for the first time the electrochemical impedance spectroscopy (EIS) measurements. This allows providing further insights in the electrical properties of these biofilms. The electroassisted catalytic reduction of molecular oxygen by the entrapped Hb, in neutral aqueous solution was also investigated. A catalytic current was observed close to the Fe(III)/Fe(II) redox potential of the immobilized Hb, and the intensity of the voltammetric cathodic peak (measured by cyclic voltammetry) is directly proportional to oxygen partial pressure. The influence of oxygen partial pressure on the impedance response of the films was also analyzed. The obtained results emphasizes the fact that the total charge transfer resistance of the modified electrode decreases with increasing oxygen partial pressure. A preliminary explanation of such an observation is discussed.
Gold Nanoparticle‐Catalyzed Silver Electrodeposition on an Indium Tin Oxide Electrode and Its Application in DNA Hybridization Transduction
Authors: Lee Thomas Ming‐Hung , Cai Hong , Hsing I‐Ming
Published: September 2004

In this work, we report a simple, rapid and sensitive approach for the electrochemical gold nanoparticle‐based DNA detection with an electrocatalytic silver deposition process. The catalytic and preferential silver electrodeposition on gold nanoparticle surfaces using an indium tin oxide (ITO) electrode at certain potentials, without any chemical pretreatments of the electrode, is demonstrated. More importantly, the application of this methodology for hybridization transduction is explored. The ITO electrode surface is first coated with an electroconductive polymer, poly(2‐aminobenzoic acid), to enable the chemical attachment of avidin molecules for the subsequent probe immobilization. The hybridization of the target with the probe in turn permits the binding of the gold nanoparticle labels to the transducer surface via biotin‐streptavidin interaction. The amount of bound gold labels, which is proportional to the amount of the target, is determined by the electrocatalytic silver deposition process. A significant improvement of the signal‐to‐background ratio is achieved with this scheme compared to the conventional chemical hydroquinone‐based silver deposition process.
Organic Phase Cyclopentadienylnickelthiolate Sensor System for Electrochemical Determination of Sulfur Dioxide
Authors: Morrin Aoife , Moutloali Richard M. , Killard Anthony J. , Smyth Malcolm R. , Darkwa James , Iwuoha Emmanuel I.
Published: September 2004

A series of cyclopentadienylnickelthiolate complexes, [Ni(PBu3)(η5‐C5H5)(SC6H4X‐4)] (X=F, Cl, Br, NH2), were shown to express stable reversible electrochemical properties even after formation of SO2 adducts in organic phase consisting of argon purged CH2Cl2/0.1 M [n‐Bu4N][BF4]. The formal potentials (E°′) values of the compounds ranged from 265 to 431 mV/Ag‐AgCl depending on the para substituent of the benzene thiolate ligand. Electrochemical, UV‐vis and 1H NMR spectroscopic analyses show that the formation of SO2 adducts causes the perturbation of the electronic density of the nickel metal center, indicated by shifts in the E°′ values of the NiII/III redox couple that is dependent on SO2 concentration. The detection limits of the resulting organic phase electrochemical gas sensor system was as low as 0.56 ppm SO2 for the fluoro complex, while the linear range was as high as 700–2000 ppm SO2 for the amino complex.
Tracking sediment redistribution in a small watershed: implications for agro‐landscape evolution
Authors: Polyakov V. O. , Nearing M. A. , Shipitalo M. J.
Published: September 2004

A new, multi‐tracer method is used to track erosion, translocation, and redeposition of sediment in a small watershed, thus allowing for the ﬁrst time a complete, spatially distributed, sediment balance to be made as a function of landscape position. A 0·68 ha watershed near Coshocton, Ohio, USA was divided into six morphological units, each tagged with one of six rare earth element oxides. Sediment translocation was evaluated by collecting run‐off and by spatially sampling the soil surface. Average measured erosion rate was 6·1 t ha−1, but varied between 40·4 t ha−1 loss from the lower channels to 24·1 t ha−1 gain on the toeslope. With this technique it was possible for the ﬁrst time to itemize the sediment budget for landscape elements into three components: (1) the soil from the element that left the watershed with run‐off; (2) soil from the element that was redeposited on lower positions, with the spatial distribution of that deposition; and (3) soil originating from the upper positions and deposited on the element, with quantiﬁcation of relative source areas. The results are incongruous with the current morphology of the watershed, suggesting that diffusion‐type erosion must also play a major role in deﬁning the evolution of this landscape. Copyright © 2004 John Wiley & Sons, Ltd.
Soil creep and convex‐upward velocity profiles: theoretical and experimental investigation of disturbance‐driven sediment transport on hillslopes
Authors: Roering Joshua J.
Published: September 2004

The movement of unconsolidated materials near the Earth's surface is often driven by disturbances that occur at a range of spatial and temporal scales. The nature of these disturbances ranges from highly variable, such as tree turnover, to periodic and predictable, such as frost heave or creep. To explore the effect of probabilistic disturbances on surface processes, we formulated a granular creep model with analogy to rate process theory (RPT) used for chemical reactions. According to the theory, individual particles must be energized to a height greater than adjacent particles in order for grain dilation and transport to occur. The height of neighbouring particles (which is akin to activation energy in chemical reactions) varies with slope angle such that energy barriers get smaller in the downslope direction as slopes steepen. When slopes approach the friction‐limited angle of repose, the height of energy barriers approaches zero and grains ﬂow in the absence of disturbance. An exponential function is used to describe the probability distribution of particle excitation height although alternative distributions are possible. We tested model predictions of granular dynamics in an experimental sandpile. In the sandpile, acoustic energy serves as the disturbance agent such that grains dilate and shear in response. Particle velocities are controlled by the frequency of energy pulses that result in grain displacement. Using tracer particles, we observed a convex‐upward velocity proﬁle near the surface of the sandpile, consistent with predictions of our RPT‐based velocity model. In addition, we depth‐integrated the velocity model to predict how ﬂux rates vary with inclination of the sandpile and observed non‐linear ﬂux–gradient curves consistent with model predictions. By varying the acoustic energy level in the experimental sandpile, we documented changes in the rate of grain movement; similar changes in modelled velocities were achieved by varying the exponent of the particle excitation probability distribution. The general agreement between observed and modelled granular behaviour in our simple laboratory sandpile supports the utility of RPT‐based methods for modelling transport processes (e.g. soil creep, frost heave, and till deformation), thus enabling us to account for the probabilistic nature of disturbances that liberate sediment in natural landscapes. Copyright © 2004 John Wiley & Sons, Ltd.
Godunov‐type adaptive grid model of wave–current interaction at cuspate beaches
Authors: Rogers Benedict D. , Borthwick Alistair G. L. , Taylor Paul H.
Published: September 2004

This paper presents a second‐order accurate Godunov‐type numerical scheme for depth‐ and period‐averaged wave–current interaction. A flux Jacobian is derived for the wave conservation equations and its eigensystem determined, enabling Roe's approximate Riemann solver to be used to evaluate convective fluxes. Dynamically adaptive quadtree grids are used to focus on local hydrodynamic features, where sharp gradients occur in the flow variables. Adaptation criteria based on depth‐averaged vorticity, wave‐height gradient, wave steepness and the magnitude of velocity gradients are found to produce accurate solutions for nearshore circulation at a half‐sinusoidal beach. However, the simultaneous combination of two or more separate criteria produces numerical instability and interference unless all criteria are satisfied for mesh depletion. Simulations of wave–current interaction at a multi‐cusped beach match laboratory data from the United Kingdom Coastal Research Facility (UKCRF). A parameter study demonstrates the sensitivity of nearshore flow patterns to changes in relative cusp height, angle of wave incidence, bed roughness, offshore wave height and assumed turbulent eddy viscosity. Only a small deviation from normal wave incidence is required to initiate a meandering longshore current. Nearshore circulation patterns are highly dependent on the offshore wave height. Reduction of the assumed eddy viscosity parameter causes the primary circulation cells for normally incident waves to increase in strength whilst producing rip‐like currents cutting diagonally across the surf zone. Copyright © 2004 John Wiley & Sons, Ltd.
Transient free‐surface flow of a viscoelastic fluid in a narrow channel
Authors: Khayat Roger E. , Pan Runling
Published: September 2004

The interplay between inertia and elasticity is examined for transient free‐surface flow inside a narrow channel. The lubrication theory is extended for the flow of viscoelastic fluids of the Oldroyd‐B type (consisting of a Newtonian solvent and a polymeric solute). While the general formulation accounts for non‐linearities stemming from inertia effects in the momentum conservation equation, and the upper‐convected terms in the constitutive equation, only the front movement contributes to non‐linear coupling for a flow inside a straight channel. In this case, it is possible to implement a spectral representation in the depthwise direction for the velocity and stress. The evolution of the flow field is obtained locally, but the front movement is captured only in the mean sense. The influence of inertia, elasticity and viscosity ratio is examined for pressure‐induced flow. The front appears to progress monotonically with time. However, the velocity and stress exhibit typically a strong overshoot upon inception, accompanied by a plug‐flow behaviour in the channel core. The flow intensity eventually diminishes with time, tending asymptotically to Poiseuille conditions. For highly elastic liquids the front movement becomes oscillatory, experiencing strong deceleration periodically. A multiple‐scale solution is obtained for fluids with no inertia and small elasticity. Comparison with the exact (numerical) solution indicates a wide range of validity for the analytical result. Copyright © 2004 John Wiley & Sons, Ltd.
Application of combined immunofluorescence and fluorescence in situ hybridization on paraffin‐embedded sections to characterize T‐cell lymphoma with EBV‐infected B‐cell blasts
Authors: Temple Genevieve K. , Sales Mark , Kernohan Neil , Scott Fiona , Meiklejohn David , Pratt Norman
Published: September 2004

Combined immunofluorescence (IF) and fluorescence in situ hybridization (FISH) on formalin‐fixed, paraffin‐embedded tissue sections were used to examine lymph node tissue from two patients diagnosed with T‐cell lymphoma with Epstein–Barr virus (EBV)–infected B‐cell blasts. The majority of cells within the samples comprised T‐cells staining positively for CD3. In addition, both patients had a population of large pleiomorphic cells that were positive for the B‐cell marker CD20 and for EBV LMP‐1. Standard PCR clonality testing of the nodes revealed both immunoglobulin heavy chain (IGH) and T‐cell receptor (TCR) clonal rearrangements in one patient, although in the other case monoclonality was demonstrated only for TCRG. Cytogenetics of cultured lymphocytes from nodal tissue revealed two apparently unrelated abnormal clones in both patients. Combined IF and FISH revealed that these phenomena reflected two abnormal populations of B‐ and T‐cells rather than reactive B‐cell hyperplasia or biphenotypic evolution from a common ancestral lymphoma. True B‐cell malignancy probably emerged within a preexisting but unrelated T‐cell lymphoma. This is the first study to relate the phenotype of the abnormal cells in such cases to specific clonal populations of cells, and it demonstrates a method that may easily be introduced into a diagnostic cytogenetics laboratory with access to standard pathology laboratory resources. © 2004 Wiley‐Liss, Inc.
Generation of a conditional allele of the CBP gene in mouse
Authors: Zhang Zuwen , Hofmann Clementine , Casanova Emilio , Schütz Günther , Lutz Beat
Published: September 2004

CREB‐binding protein (CBP) is an important transcriptional cofactor for various intracellular signaling pathways, including Ca2+‐ and cAMP‐mediated gene activation. The loss of one CBP allele causes the human Rubinstein‐Taybi syndrome, which is characterized by mental retardation and other severe developmental defects. Deletion of both CBP alleles in the mouse leads to early embryonic lethality. To address the function of CBP in late embryogenesis and in adult physiology, a floxed CBP allele (CBPfl) was generated. Using the Cre/loxP recombination system, CBP function was disrupted in principal forebrain neurons by breeding with a transgenic CaMKIIα‐Cre mouse line to obtain CBPfl/fl;CaMKIIαCre mice. These mice contain CBPstop523 alleles specifically in principal forebrain neurons, presumably resulting in the production of a truncated CBP protein unable to interact with a number of transcription factors, including phosphorylated CREB. genesis 40:82–89, 2004. © 2004 Wiley‐Liss, Inc.