bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basic concepts of quantum systems versus classical networks
Authors: Civalleri Pier Paolo , Gilli Marco , Bonnin Michele 
Published: September 2004

AbstractThe 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

AbstractNanoantennas 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

AbstractFundamental 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

AbstractA 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

AbstractCauliflower‐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

AbstractThin 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

AbstractNanostructured 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

AbstractWe 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

AbstractIt 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractReaction 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

AbstractThe 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

AbstractMethyl 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

AbstractWith 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

AbstractTransesterification 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.