bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymptotic behaviour of curved rods by the unfolding method
Authors: Griso Georges
Published: August 2004

We consider in this work general curved rods with a circular cross‐section of radius δ. Our aim is to study the asymptotic behaviour of such rods as δ→0, in the framework of the linear elasticity according to the unfolding method. It consists in giving some decompositions of the displacements of such rods, and then in passing to the limit in a fixed domain.

A first decomposition concerns the elementary displacements of a curved rod which characterize its translations and rotations, and the residual displacements related to the deformation of the cross‐section. The second decomposition concerns the displacements of the middle‐line of the rod. We prove that such a displacement can be written as the sum of an inextensional displacement and of an extensional one. An extensional displacement will modify the length of the middle‐line, while an inextensional displacement will not change this length in a first approximation. We show that the H1‐norm of an inextensional displacement is of order 1, while that of an extensional displacement is in general, of order δ.

A priori estimates are established and convergence results as δ→0, are given for the displacements. We give their unfolded limits, as well as the unfolded limits of the strain and stress tensors. To prove the convergence of the strain tensor, the introduction of elementary and residual displacements appears as essential. By passing to the limit as δ→0 in the linearized system of the elasticity, we obtain on the one hand, a variational problem that is satisfied by the limit extensional displacement, and on the other hand, a variational problem coupling the limit of inextensional displacements and the limit of the angle of torsion. Copyright © 2004 John Wiley & Sons, Ltd.
Assessing weak intramolecular donor–acceptor interactions using 1H117Sn J‐HMQC spectroscopy
Authors: Biesemans Monique , Martins José C. , Jurkschat Klaus , Pieper Nicole , Seemeyer Stefan , Willem Rudolph
Published: August 2004

It is demonstrated that long‐range nJ(1H,117Sn) coupling constants down to 0.3 Hz, can be accurately quantified from non‐linear fitting of the sine modulation of the associated 1H117Sn correlation cross‐peak intensities sampled as a function of the heteronuclear antiphase coherence preparation time in the 1H117Sn J‐HMQC pulse sequence. The contribution of additional, undesired modulations is illustrated and assessed using the product operator formalism, and is traced back to contributions that arise from miss‐setting of the wandering 180° pulse angle in the constant time period. The power of the method and its use in the characterization of weak intramolecular donor–acceptor interactions are illustrated by the determination of long‐range nJ(1H,117Sn) coupling constants of bis[3‐(dimethylamino)propyl]tin derivatives, [Me2N(CH2)3]2SnR2 (2, R = Me; 3, R = Ph; 4, R = t‐Bu). By comparing these with the values found for the corresponding bis(4‐methylpentyl)tin derivatives, [Me2CH(CH2)3]2SnR2 (2′, R = Me; 3′, R = Ph), which lack such interactions, the use of long‐range coupling constants to detect intramolecular donor–acceptor interactions is evaluated. It is concluded that nJ(1H,117Sn) couplings up to six bonds through an organic carbon chain can be quantified, whether donor–acceptor interactions are present or not. Furthermore, evidence is presented that, when two scalar coupling pathways co‐exist, the pathway involving an intramolecular donor–acceptor interaction can have opposite sign, thus decreasing the overall coupling constant to a value smaller than that actually measured in the absence of a donor–acceptor interaction, where only one coupling pathway is active. There is nevertheless clear numerical value discrimination in the series of compounds investigated between long‐range couplings in derivatives without weak intramolecular donor–acceptor interactions and those where such interactions can exist. Copyright © 2004 John Wiley & Sons, Ltd.
NMR investigations of Co(III) coordination compounds oriented in a dilute lyotropic liquid crystal
Authors: Pellizer Giorgio , Asaro Fioretta , Pergolese Barbara
Published: August 2004

A swollen lamellar phase, based on sodium dodecyl sulfate, pentanol and NaBr brine, was examined by means of NMR spectroscopy of isotopes with quadrupolar characteristics, namely 2H, 17O, 23Na and 81Br, present at natural abundance. Such a dilute lyotropic liquid crystal was capable of inducing a preferential orientation of the cobalt coordination compounds [Co(en)3]3+ and Co(acac)3, the 59Co NMR signals of which displayed quadrupolar splittings. Moreover, it imparted alignment in the magnetic field to the organocobaloxime [ClCD2Co(Hdmg)2H2O], as shown by the quadrupolar splitting of the deuterium of the axial ligand. Copyright © 2004 John Wiley & Sons, Ltd.
A simple molecule with a complex crystal structure: interplay of 31P solid‐state NMR spectroscopy and single‐crystal x‐ray diffraction in the structure determination of a ruthenium diphosphine diamine complex
Authors: Eichele Klaus , Nachtigal Christiane , Jung Susanne , Mayer Hermann A. , Lindner Ekkehard , Ströbele Markus
Published: August 2004

A comprehensive 31P solid‐state NMR study of Ru(η1‐Ph2PCH2CH2OCH3)2(η2‐en)Cl2 (en = ethylenediamine) (1), by 1D (contact time variation, inversion–recovery, SPARTAN) and 2D techniques (homonuclear J‐resolved, SECSY) indicated that the crystal structure of 1 should be complex. The single‐crystal x‐ray structure determination confirmed the presence of eight independent molecules in the asymmetric unit, with 31P isotropic chemical shifts in the range 27.3–40.1 ppm, while the spans of the phosphorus chemical shift tensors are of the order of 170 ppm. Based on unique structural features and NMR data, one molecule has been tentatively assigned. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling of earth and water pressure development during diaphragm wall construction in soft clay
Authors: Schäfer R. , Triantafyllidis Th.
Published: August 2004

The influence of a diaphragm wall construction on the stress field in a soft clayey soil is investigated by the use of a three‐dimensional FE‐model of seven adjacent wall panels. The installation procedure comprises the excavation and the subsequent pouring of each panel taking into account the increasing stiffness of the placed fresh concrete. The soft clay deposit is described by a visco‐hypoplastic constitutive model considering the rheological properties and the small‐strain stiffness of the soil. The construction process considerably affects the effective earth and pore water pressures adjacent to the wall. Due to concreting, a high excess pore water pressure arises, which dissipates during the following construction steps. The earth pressure finally shows an oscillating, distinct three‐dimensional distribution along the retaining wall which depends on the installation sequence of the panels and the difference between the fresh concrete pressure and the total horizontal earth pressure at rest. In comparison to FE‐calculations adopting the earth pressure at rest as initial condition, greater wall deflections and surface ground settlements during the subsequent pit excavation can be expected, as the average stress level especially in the upper half of the wall is increased by the construction procedure of the retaining structure. Copyright © 2004 John Wiley & Sons, Ltd.
Medical event profiling of COPD patients
Authors: Hansell A. L. , Lam K. A. , Richardson S. , Visick G. , Soriano J. B.
Published: August 2004

Purpose

This analysis proposes appropriate descriptive and analytical statistical techniques to profile medical events requiring GP consultation using the example of chronic obstructive pulmonary disease (COPD).

Methods

Consultation patterns were examined for 1807 cases with a diagnosis compatible with COPD in 1998 and a group of controls matched by sex, age and practice from the General Practice Research Database, a nationally representative UK primary care database. Consulting patterns by Read code chapter and chapter subdivision were examined using cluster analysis, logistic regression and classification and regression trees (CART).

Results

CART and multivariate logistic regression analyses suggested that COPD patients were more likely to consult with pulmonary circulatory disease (multivariate OR: 7.46 (95% confidence intervals: 2.05, 20.01) ), non‐COPD respiratory diseases (2.77 (2.28, 3.37)), mycoses (2.0 (1.43, 2.71)), ‘symptoms or ill‐defined conditions’ (1.95 (1.68, 2.29)), or other forms of heart disease (1.84 (1.92, 2.64)), and less likely to consult with hypertensive diseases (0.73 (0.57, 0.96)). Regression also showed positive associations with digestive system diseases (OR: 1.31 (1.02, 1.68)) and negative associations with ‘other viral or chlamydial disease’ (0.16 (0.03, 0.88)). A borderline significance reduced risk for cancers was seen in univariate logistic regression analyses. Cluster analyses were not useful in discriminating between cases and controls.

Conclusions

These analyses provide information about the natural history of COPD and could be used to help interpret or detect adverse drug reactions if repeated before and after introduction of a treatment. COPD can be considered a multicomponent disease with more frequent comorbidities than age‐ and gender‐matched individuals without COPD. Copyright © 2004 John Wiley & Sons, Ltd.
The secretome of the plant pathogenic bacterium Erwinia chrysanthemi
Authors: Kazemi‐Pour Nasrin , Condemine Guy , Hugouvieux‐Cotte‐Pattat Nicole
Published: August 2004

Erwinia chrysanthemi causes soft‐rot diseases of many plants by secreting a battery of enzymes which degrade the plant cell walls. We initiated a proteomic analysis to create a reference map of the E. chrysanthemi secretome. Extracellular proteins were isolated from E. chrysanthemi culture supernatants and resolved by two‐dimensional electrophoresis. By analysis of mutants, Western blotting, and matrix‐assisted laser desorption/ionization‐time of flight (MALDI‐TOF) 55 spots representing 25 unique proteins were identified. In uninduced conditions, we identified spots corresponding to the cellulase Cel5, the proteases PrtA, PrtB, and PrtC, the flagellin FliC, and some intracellular proteins whose presence probably resulted from spontaneous cell lysis. We identified another secreted protein, AvrL, homologous to an avirulence protein of Xanthomonas campestris. After culture in conditions inducing pectinase production, i.e., in the presence of galacturonate and plant extract, we identified spots corresponding to the endopectate lyases PelA, PelB, PelC, PelD, PelE, PelI, PelL, and PelZ, the pectin acetylesterases PaeX and PaeY, the pectin methylesterase PemA, and the polygalacturonase PehX. In the presence of other inducing compounds, we detected the rhamnogalacturonate lyase RhiE and the esterase FaeD. Analysis of mutants, altered for one type of secretion system, was performed to determine the targets of each system. The type I system Prt was necessary for the secretion of three proteases. No proteins secreted by the type III Hrp system could be detected in E. chrysanthemi supernatants. In addition to the already known substrates (eleven pectinases and one cellulase), this analysis revealed that the type II Out system mediates secretion of the esterase FaeD and of the Avr‐like protein AvrL.
Lipid raft proteomics: Analysis of in‐solution digest of sodium dodecyl sulfate‐solubilized lipid raft proteins by liquid chromatography‐matrix‐assisted laser desorption/ionization tandem mass spectrometry
Authors: Li Nan , Shaw Andrew R. E. , Zhang Nan , Mak Allan , Li Liang
Published: August 2004

Lipid rafts are glycolipid‐ and cholesterol‐enriched membrane microdomains implicated in membrane signaling and trafficking. The highly hydrophobic nature of lipid raft proteins pose significant problems of solubilization and recovery that hinder analysis by mass spectrometry (MS) and may under‐report the composition of lipid rafts. In a previous investigation of the monocyte lipid raft in which proteins were digested with trypsin following polyacrylamide gel electrophoresis we identified 52 proteins. Here we report the development of a sodium dodecyl sulfate (SDS)‐aided approach in which proteins are digested in solution and examined by high‐performance liquid chromatography‐matrix‐assisted laser desorption/ionization‐tandem mass spectrometry (HPLC‐MALDI‐MS/MS) using a novel LC‐MALDI interface thereby circumventing the need to separate proteins on gels. Using this approach we identified 71 proteins in the lipid raft, 45 of which were not detected using in‐gel digestion. Among the new proteins are α‐ and β‐tubulin, tubulinspecific chaperone A, a folding protein involved in tubulin dimer assembly, and KIF13, a microtubule motor protein indicating that proteins involved in microtubule assembly and trafficking are more readily detected using an in‐solution approach. To investigate why tubulin was not identified by in‐gel digestion, we compared the distribution of α‐tubulin and the raft marker flotillin‐2 in buoyant density gradients before and after separation on SDS‐gels. Both proteins were present in the raft fractions, but tubulin was selectively lost following separation on SDS‐gels. Assemblies of cytoskeletal proteins with lipid rafts may therefore be resolved using in‐solution digestion that would be missed using gel‐based approaches.
(−)‐Sparteine: The compound that most significantly influenced my research
Authors: Okamoto Yoshio
Published: August 2004

A chiral diamine alkaloid, (−)‐sparteine (Sp), has been found to be very effective as a ligand for Grignard reagents when used for the enantiomer‐selective polymerization of racemic RS‐1‐phenylethyl methacrylate. The enantiomeric excess of the initially polymerized monomer is 93%, and at about a 60% conversion, nearly optically pure R‐monomer is recovered. This enantiomer selectivity is today the highest in polymer chemistry. Triphenylmethyl methacrylate (TrMA) is a unique monomer that gives a highly isotactic polymer even during radical polymerization. When TrMA is polymerized with the Sp complex with n‐butyllithium in toluene at −78 °C, an optically active, isotactic polymer [poly(triphenylmethyl methacrylate) (PTrMA)] with a one‐handed helical conformation is obtained. The helical structure is maintained even at room temperature in solution. Analogous helical polymethacrylates that show various conformational changes have also been found. One‐handed helical PTrMA exhibits high chiral recognition to a variety of racemates as a chiral stationary phase (CSP) for high‐performance liquid chromatography. This finding has led to the development of very powerful CSPs based on polysaccharides, such as cellulose and amylose. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4480–4491, 2004
Enantiomer‐selective radical cyclopolymerization of rac‐2,4‐pentanediyl dimethacrylate using a ruthenium‐mediated chiral atom transfer radical polymerization initiating system
Authors: Tsuji Masashi , Aoki Towako , Sakai Ryosuke , Satoh Toshifumi , Kaga Harumi , Kakuchi Toyoji
Published: August 2004

The enantiomer‐selective radical polymerization of rac‐2,4‐pentanediyl dimethacrylate, an equimolar mixture of (2S,4S)‐2,4‐pentanediyl dimethacrylate (SS‐1) and (2R,4R)‐2,4‐pentanediyl dimethacrylate (RR‐1), was carried out with a chiral atom transfer radical polymerization initiating system consisting of methyl 2‐bromoisobutyrate (3), dichlorotris(triphenylphosphine)ruthenium [RuCl2(PPh3)3], and a chiral additive in anisole at 60 °C. When (S)‐1,1′‐bi‐2‐naphthol (a‐3) was used as the chiral additive, the recovered monomer was enriched in SS‐1, and the enantiomeric excess was 16.9% at a 22.6% monomer conversion. The specific rotation ([α]435, c 0.3, CHCl3) of the resulting polymer was +40.3° at a 22.6% monomer conversion. For the copolymerization of SS‐1 and RR‐1 with 3/RuCl2(PPh3)3/a‐3 in anisole at 60 °C, the monomer reactivity ratio for RR‐1 (rR) was determined to be 4.94, and that for SS‐1 (rS) was 0.27. For the homopolymerizations of SS‐1 and RR‐1 with 3/RuCl2(PPh3)3/a‐3 in anisole at 60 °C, the polymerization rate of RR‐1 was considerably faster than that of SS‐1, and the rate constants for the homopolymerizations were determined to be kSS = 2.0 × 10−3 h−1 and kRR = 8.2 × 10−3 h−1, respectively. With the values of kSS, kRR, rR, and rS, the relative ratio kSS/kRR/kSR/kRS was determined to be 1.2:4.9:4.5:1, which indicated that both the growing end of SS‐1 and that of RR‐1 preferentially reacted with RR‐1. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4563–4569, 2004
Helicity induction on a poly(phenylacetylene) bearing a phosphonate residue by chiral dendrons
Authors: Kamikawa Yuko , Kato Takashi , Onouchi Hisanari , Kashiwagi Daisuke , Maeda Katsuhiro , Yashima Eiji
Published: August 2004

A series of optically active dendrons with a primary amino group at the terminal were prepared from L‐ or D‐glutamic acid, and their helicity induction abilities for a poly(phenylacetylene) bearing a phosphonate pendant were characterized with ultraviolet–visible and circular dichroism spectroscopy. The magnitude of the Cotton effects of the polymer induced by the dendrons significantly increased upon complexation with a higher generation dendron. The effect of the chirality of the glutamate residues (L and D) on the helicity induction was also studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4580–4586, 2004
X‐ray photoelectron spectroscopic study of surface modification of low‐k organic materials by plasma treatment
Authors: Uchida Y. , Fukuda T. , Yanazawa H.
Published: August 2004

The surface modification of SiLK™ resin (trademark of the Dow Chemical Company) by means of N2 or Ar plasma treatment was studied using XPS. This surface modification is supposed to improve the adhesion of tantalum. XPS spectra of the surface of plasma‐treated resin exhibited an oxygen peak, and also a nitrogen peak after N2 plasma treatment, in addition to a carbon peak. The plasma treatment was found to break some of the CC bonds and to cause the disappearance of components related to aromatic rings. In consequence, carbon components with low amounts of oxygen are produced which are probably from the atmosphere. In addition, the N2 plasma also nitrides the surface layer. The Ar plasma produces damage, such as unbonded carbon atoms, that can reach deeper into the resin films if the exposure time is long enough; while N2 plasma prevents the penetration of damage, probably because of the nitride layer on the surface. The plasma treatment produces phenomena like the restructuring of carbon bonds. Furthermore, the XPS analysis indicates that oxidation of the resin at the surface suppresses the reaction between the resin and Ta, resulting in a more metal‐like Ta layer. The reconstructed surface layer resulting from the bonding of unbonded carbon atoms with other atoms should provide better adhesion, thus allowing deposition of a Ta layer with a different chemical state. Copyright © 2004 John Wiley & Sons, Ltd.
EXELFS characterization of Mg vanadate
Authors: Márquez F.
Published: August 2004

In this paper we show the preliminary results obtained by EXELFS spectroscopy (in reflection mode) on polycrystalline magnesium orthovanadate. The oscillating features observed beyond the V L2, 3‐edge have been isolated and analysed following the EXAFS procedure. EXELFS revealed that by thermal treatment in air or vacuum, reversible structural variations occur around vanadium. Thus, by calcination in air at 573 K, vanadium appeared in the +5 state (orthovanadate) showing a VO distance of 0.183 nm. By thermal annealing at 823 K in vacuum, vanadium was partially reduced to V4+ and the VO distance decreased from 0.183 nm to 0.163 nm. Copyright © 2004 John Wiley & Sons, Ltd.
XPS investigations of Sn, SnPd and SnPd/Cu clusters produced by electroless deposition onto NiTi micronic particles formed by atomization
Authors: Silvain J. F. , Fouassier O.
Published: August 2004

XPS analysis of electroless deposition of successive SnPd and Cu films on a NiTi surface has been performed in order to explain the nucleation and growth. Chemical interaction of Sn with the NiTi surface is shown to be associated with the growth of Sn oxide and hydroxide that can be formed after the reaction of Sn atoms with TiO2 oxide. 3D growth of pure metallic palladium occurs, leading to the formation of nanometric metallic Pd clusters. The interaction of copper atoms with the palladium surface leads to the formation of interfacial PdCu intermetallic and consequently to strong interfacial adhesion. Copyright © 2004 John Wiley & Sons, Ltd.
Surface roughness and island formation effects in ARXPS quantification
Authors: Martín‐Concepción A. I. , Yubero F. , Espinós J. P. , Tougaard S.
Published: August 2004

Quantification of surface nano‐structures by angle‐resolved XPS (ARXPS) is straightforward and works quite reliably for perfectly flat surfaces of amorphous materials. For rough surfaces, the interpretation of ARXPS is, however, complicated because the angular variation of the XPS peak intensity depends on the surface roughness. Even for ideally flat substrates, ARXPS analysis of laterally inhomogeneous surface structures grown on the surface is quite complex. The reason is that neighboring nano‐clusters shadow the XPS peak intensity. The effect depends on cluster shape as well as the distribution of clusters on the surface. In addition the effects depend on the flatness of the underlying substrate. The interpretation of ARXPS then becomes quite complex. In the present paper, we have studied this problem by analyzing ZnO nano‐clusters grown on substrates of SiO2 and Al2O3. Thus we compared the results of quantification by the four techniques: ARXPS, XPS‐peak shape analysis, Rutherford backscattering spectroscopy and x‐ray fluorescence spectrometry. While the latter three techniques gave consistent results, the results of the ARXPS analysis were way off. This deviation is discussed in terms of the above‐mentioned shadowing effect of neighboring clusters as well as roughness of the underlying substrates. Different normalization methods in the ARXPS analysis procedure are compared and it is found that some of the observed problems for the substrate peaks (but not for the peaks from the overlayer film) can be reduced by applying reference samples with similar roughness for normalization of the data. In conclusion, the ARXPS technique is very much dependent on surface roughness as well as on the morphology of the thin films. Thus for reliable quantification with ARXPS it is necessary to have independent knowledge on surface roughness as well as the distribution of islands of the thin films. Copyright © 2004 John Wiley & Sons, Ltd.
Elastic electron backscattering from silicon surfaces: effect of charge‐carrier concentration
Authors: Zemek J. , Jiricek P. , Lesiak B. , Jablonski A.
Published: August 2004

Silicon wafers, p‐ and n‐doped with different free‐carrier charge concentrations, were selected as model materials to study a possible influence of charge‐carrier concentrations (or electrical conductivity) on measured elastic electron backscattering probabilities and electron inelastic mean free paths determined by elastic peak electron spectroscopy. This research is motivated by contrast changes frequently observed in scanning electron microscopy of semiconductor structures with different types of doping (p‐ and/or n‐) and/or different electrical conductivities. The results show that the measured elastic electron backscattering probabilities and the inelastic mean free paths differ only within experimental uncertainties. They are independent of the type (p‐ and/or n‐) of doping and the free‐carrier charge concentration. Copyright © 2004 John Wiley & Sons, Ltd.
Depth profiling of rolled aluminium alloys by means of GDOES
Authors: Kuypers S. , Buytaert G. , Terryn H.
Published: August 2004

Rolling of aluminium alloys is known to alter the surface properties. Radiofrequency glow discharge optical emission spectrometry (RF GDOES) was introduced to study the elemental composition of the surface and near‐surface regions of a commercial AA3005 hot‐rolled aluminium alloy, before and after annealing treatments for full (bulk) recrystallization. Qualitative GDOES depth profiles (signal intensity as a function of sputtering time) suggest enrichment of some and depletion of other alloying elements as well as the introduction of impurity elements within the disturbed surface layer of the alloy. The depth profiles are correlated with SEM/EDXA observations in the GDOES craters. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative evaluation of contributions to interface broadening in metal/silicon multilayers
Authors: Kovač Janez , Zalar Anton
Published: August 2004

Auger electron spectroscopy (AES) depth profiling is a widely used technique to study buried interfaces in thin‐film structures. It involves a sputtering process that may cause topographical and compositional changes in the surface region of the ion‐bombarded sample. In order to reveal the original in‐depth elemental distribution, it is important to know the influence of the sputtering process.

AES depth profiling of Si/Ti, Si/Ni, Si/Nb and Si/W layered structures was performed with 1 and 3 keV Ar+ ions at an incidence angle of 47°. The mixing–roughness–information depth (MRI) model was used to estimate different contributions to the interface broadening. A stronger broadening of the metal/Si interfaces than that of the Si/metal interfaces can be explained by ion bombardment induced roughening and mixing of metallic atoms with the silicon ones. Copyright © 2004 John Wiley & Sons, Ltd.
Structural investigations of ternary chalcogenide glasses
Authors: Petkova T. , Petkov P. , Vassilev S. , Nedeva Y.
Published: August 2004

Glasses from (GeSe5)1−xGax and (GeSe4)1−xGax (x = 5, 10, 15, 20 at.%) systems have been investigated. X‐ray diffraction and IR scattering measurements have been carried out in order to elucidate the structure of the glasses. From the x‐ray diffraction data radial distribution functions (RDF) have been obtained. The results show that the basic units are tetrahedral and the atoms are distributed according to the ‘chemically ordering’ model. The IR spectra reveal that the introduction of gallium to GexSe1−x glass thus causes only a small shift of maxima and some changes in the broadness of the vibration bands. The presence of a shoulder at 216 cm−1 and the increase of this shoulder is associated with the increase in gallium content. The effect of gallium incorporation in the binary GexSe1−x glassy system has been discussed in terms of the chemically ordered model and experimental data of both investigations. Copyright © 2004 John Wiley & Sons, Ltd.
Nb2O5 thin films obtained by chemical spray pyrolysis
Authors: Romero R. , Ramos‐Barrado J. R. , Martin F. , Leinen D.
Published: August 2004

Nb2O5 thin films have been prepared by chemical spray pyrolysis on fused silica and glass substrates from a 10−2 M NbCl5 precursor solution of 50% bidistilled water, 49% ethanol and 1% acetic acid. The films are of compact material with high surface roughness, that decrease with increasing substrate temperature (350 °C to 500 °C) while the deposition velocity decreases. All as‐deposited films are amorphous. Post‐annealing in air to temperatures higher than 500 °C leads to a distorted hexagonal crystal phase. With XPS and depth profiling, the stoichiometry and residuals from the precursor solution in these films have been investigated. In particular, the decomposition of the alcoholic component by post‐annealing could be followed with XPS. Copyright © 2004 John Wiley & Sons, Ltd.
Enhanced scanning ion microprobe image analysis for rough surface samples as an alternative to SIMS depth profiling
Authors: Seki S. , Tamura H. , Horita S. , Ito N.
Published: August 2004

The usefulness of scanning ion microprobe (SIM) image analysis by a gallium focused ion beam (FIB) on a bevelled sample surface is investigated. To improve the low secondary ionization yields of elements caused by the gallium bombardment, the oxygen ions for the positive ion detection and the caesium ions for the negative ion detection were in‐situ implanted with a dose of 1016–1017 atoms/cm2 prior to imaging analysis. A significant enhancement of ion image sensitivity in the ion‐implanted area compared with that in the non‐implanted area was observed. The enhanced SIM image analysis for the highly magnified bevel is especially useful for multilayered structures with rough surfaces. That is because the secondary ion mass spectrometry (SIMS) depth profiles for the rough surface samples do not give accurate depth information due to the significant distortion and degradation of the profiles caused by uneven etching. This technique can be an alternative to the SIMS depth profiling for rough surface samples. Copyright © 2004 John Wiley & Sons, Ltd.
Surface defects on collection coins of precious metals
Authors: Gusmano G. , Montanari R. , Kaciulis S. , Mezzi A. , Montesperelli G. , Rupprecht L.
Published: August 2004

The presence of various defects of different colours and sizes on precious collection coins is the cause not only of the rejection of defective coins but also of an increase in the production costs. In this work, the surface defects on the Austrian collection coins have been investigated by using the techniques of XPS, AES and SEM/EDS.

Multi‐technique surface analysis revealed the presence of silver and sulfur in the stains on the golden coins. Auger spectra and chemical images proved that both Ag and S are located in the coloured surface areas. From the XPS results, it was concluded that the coloured stains consist of Ag2S. XPS depth profiling revealed the difference in the thickness of the dark‐grey and red stains. In both cases, the topmost layer of silver sulfide has a thickness of a few nm, whereas the inner layer of silver is about 300 nm thick in the dark stains and only about 2–3 nm in the red ones. The origin of these stains has been attributed to foreign particles of silver embedded onto the coins.

The chemical composition of the visible stains on silver coins is quite different. AES results revealed that some defects contain chlorine, potassium and oxygen; the others include iron and oxygen. In all these cases, the surface contaminants were attributed to occasional problems that occurred during the manufacture of the coin. Copyright © 2004 John Wiley & Sons, Ltd.
XPS and atomic force microscopy analyses of thin Au and Cu films on Pd
Authors: Maluf S. S. , Gobbi A. L. , Paulin‐Filho P. I. , Nascente P. A. P.
Published: August 2004

The surface properties of bimetallic systems have been studied recently due to possible applications in different areas, such as electrochemistry, magnetism, and catalysis. Understanding of the atomic and electronic structures is crucial for designing metallic devices. In this work, thin films of gold and copper were grown on a polycrystalline palladium substrate by sputtering. For both films, the thickness was estimated to be 10 nm. The morphology of the films was investigated by atomic force microscopy (AFM). XPS was employed in order to verify the possibility of alloy formation. Oxide formation was observed for the Cu film, but not for the Au film. The copper oxide (CuO) was removed by argon ion sputtering. Alloying was not observed in the Au/Pd or Cu/Pd films. Copyright © 2004 John Wiley & Sons, Ltd.
SIMS investigation of the influence of Ge pre‐deposition on the interface quality between SiC and Si
Authors: Pezoldt J. , Zgheib Ch. , Masri P. , Averous M. , Morales F. M. , Kosiba R. , Ecke G. , Weih P. , Ambacher O.
Published: August 2004

SiC/Si(111) heterostructures formed by using an alternative method for stress relaxation were investigated by SIMS and AES. The applied stress reduction method is based on a theoretical approach, which predicts an improvement of the SiC layer quality if Group IV elements are incorporated into the interface between SiC and Si. Germanium was chosen to test this approach. The incorporation of Ge into the heterointerface was carried out by depositing different amounts of Ge prior to the SiC growth process and varying the Ge deposition temperature. SIMS investigations revealed that Ge remains near the SiC/Si interface independently of the pre‐deposited amount of Ge. In the case of two monolayers (ML) Ge coverage (with respect to the silicon surface) a surface segregation was observed. This indicates a limited transport of Ge to the SiC surface through the growing SiC layer due to grain boundary diffusion. At Ge coverages between 0.5 ML and 2 ML a sharper interface between the SiC and Si was observed. In this case the tail of the carbon distribution remains within the region occupied by the Ge distribution. The incorporation of Ge at the interface suppresses the out‐diffusion of Si from the substrate to the surface of the growing SiC layer and, therefore, impedes the formation of voids at the SiC/Si interface. Copyright © 2004 John Wiley & Sons, Ltd.
Opioids and central sensitisation: II. Induction and reversal of hyperalgesia
Authors: Ruscheweyh Ruth , Sandkühler Jürgen
Published: August 2004

Opioids are powerful analgesics when used to treat acute pain and some forms of chronic pain. In addition, opioids can pre‐empt some forms of central sensitization {Sandkühler and Ruscheweyh, Eur. J. Pain, in press, doi:10.1016/j.ejpain.2004.05.012}. Here we review evidence that opioids may also induce and perhaps reverse some forms of central sensitization.
Opioids and central sensitisation: I. Pre‐emptive analgesia
Authors: Sandkühler Jürgen , Ruscheweyh Ruth
Published: August 2004

Opioids are powerful analgesics when used to treat acute pain and some forms of chronic pain. A large body of literature has shown that opioids can, in addition, also prevent (this review) or induce and perhaps reverse {Ruscheweyh and Sandkühler, Eur. J. Pain, in press, doi:10.1016/j.ejpain.2004.05.011} some forms central sensitisation in in vitro and in vivo animal models of pain. However, the concept of central sensitisation is, at present, ambiguous and the usefulness of opioids as pre‐emptive analgesics in human pain patients is still not clear.
Aminoethyl benzenesulfonyl fluoride and its hexapeptide (Ac‐VFRSLK) conjugate are both in vitro inhibitors of subtilisin kexin isozyme‐1
Authors: Basak Sarmistha , Stewart Nicolas A. , Chrétien Michel , Basak Ajoy
Published: August 2004

Using a number of intramolecularly quenched fluorogenic (IQF) substrates encompassing the subtilisin kexin isozyme‐1 (SKI‐1)‐mediated cleavage sites of various viral glycoproteins, it is revealed that 4‐[2‐minothyl enzene] ulfonylluoride (AEBSF) can inhibit the proteolytic activity of SKI‐1 mostly in a competitive manner. The measured IC50 values range from 200 to 800 nM depending on the nature of the substrate used. This is the first in vitro demonstration of a non‐peptide inhibitor of SKI‐1. In an effort to enhance the selectivity and potency of SKI‐1 inhibition, a hexapeptidyl derivative containing SKI‐1 consensus sequence, Ac‐Val‐Phe‐Arg‐Ser‐Leu‐Lys‐AEBSF, was prepared. The peptide sequence was derived from the primary auto‐activation site of prodomain of SKI‐1 itself terminating at Leu‐Lys138 and contains the crucial P4‐basic and P2 alkyl side chain containing hydrophobic amino acids. Like AEBSF, the hexapeptidyl‐AEBSF analog blocked SKI‐1 cleavages of all IQF‐substrates tested but with enhanced efficiency.
Control of specific gene expression in mammalian cells by co‐expression of long complementary RNAs
Authors: Tran Nham , Raponi Mitch , Dawes Ian W. , Arndt Greg M.
Published: August 2004

The use of long double‐stranded RNA (dsRNA) for gene silencing in mammalian cells has generally been restricted to embryonic cell types and proposed to induce non‐specific effects on gene expression in differentiated cells. In this study, we report that foreign and endogenous gene expression can be regulated in immortalised human cell lines by co‐expression of long complementary RNAs with the potential to form dsRNA. The observed gene silencing effect was transferable to recipient control cells, occurred independently of cytoplasmic Dicer and produced an epi‐allelic series of clones suitable for gene function studies. This complementary RNA co‐expression approach permits the use of long complementary RNAs for regulating specific gene expression in mammalian cells.
Stimulators of AMP‐activated protein kinase inhibit the respiratory burst in human neutrophils
Authors: Alba Gonzalo , El Bekay Rajaa , Álvarez-Maqueda Moisés , Chacón Pedro , Vega Antonio , Monteseirı́n Javier , Santa Marı́a Consuelo , Pintado Elı́zabeth , Bedoya Francisco J. , Bartrons Ramon , Sobrino Francisco
Published: August 2004

In the present study, we have examined the potential ability of 5′‐AMP‐activated protein kinase (AMPK) to modulate NADPH oxidase activity in human neutrophils. AMPK activated with either 5′‐aminoimidazole‐4‐carboxamide ribonucleoside (AICAR) or with 5′‐AMP significantly attenuated both phorbol 12‐myristate 13‐acetate (PMA) and formyl methionyl leucyl phenylalanine‐stimulated superoxide anion (O2

−) release by human neutrophils, consistently with a reduced translocation to the cell membrane and phosphorylation of a cytosolic component of NADPH oxidase, namely p47phox. AMPK was found to be present in human neutrophils and to become phosphorylated in response to either AICAR or other stimulators of its enzyme activity. Furthermore, AICAR also strongly reduced PMA‐dependent H2O2 release, and induced the phosphorylation of c‐jun N‐terminal kinase 1 (p46), p38 mitogen‐activated protein kinase and extracellular signal‐regulated kinase. Present data demonstrate for the first time that the activation of AMPK, in states of low cellular energy charge (such as under high levels of 5′‐AMP) or other signals, could be a factor contributing to reduce the host defense mechanisms.
Aquaporin homologues in plants and mammals transport ammonia
Authors: Jahn Thomas P. , Møller Anders L.B. , Zeuthen Thomas , Holm Lars M. , Klærke Dan A. , Mohsin Brigitte , Kühlbrandt Werner , Schjoerring Jan K.
Published: August 2004

Using functional complementation and a yeast mutant deficient in ammonium (NH4
+) transport (Δmep1–3), three wheat (Triticum aestivum) TIP2 aquaporin homologues were isolated that restored the ability of the mutant to grow when 2 mM NH4
+ was supplied as the sole nitrogen source. When expressed in Xenopus oocytes, TaTIP2;1 increased the uptake of NH4
+ analogues methylammonium and formamide. Furthermore, expression of TaTIP2;1 increased acidification of the oocyte‐bathing medium containing NH4
+ in accordance with NH3 diffusion through the aquaporin. Homology modeling of TaTIP2;1 in combination with site directed mutagenesis suggested a new subgroup of NH3‐transporting aquaporins here called aquaammoniaporins. Mammalian AQP8 sharing the aquaammoniaporin signature also complemented NH4
+ transport deficiency in yeast.
A Comparative Analysis of the Biomechanical Behaviour of Five Flexor Tendon Core Sutures
Authors: VIINIKAINEN A. , GÖRANSSON H. , HUOVINEN K. , KELLOMÄKI M. , ROKKANEN P.
Published: August 2004

Five core suture techniques were compared by static tensile testing in vitro. Fifty porcine tendons were used. The core sutures were performed with 3-0 or 4-0 braided polyester suture (Ticron®) and the over-and-over running peripheral sutures with 6-0 monofilament polypropylene (Prolene®). The core sutures were: (1) Pennington modified Kessler (3-0), (2) Double Pennington modified Kessler (3-0), (3) 4-strand Savage (3-0), (4) 4-strand Savage (4-0), and (5) 6-strand Savage (4-0). Repairs were compared as paired in regard to one variable: the number of core suture strands, the suture calibre, or the suture configuration. Biomechanical differences between the repair groups started during the linear region, with the yield force and stiffness increasing along with the number of core suture strands. All three variables influenced the strain at the yield point. Thus, the strength of the intact repair can be improved by modifying the core suture. In all repairs gap formation started near the yield point after failure of the peripheral suture. The yield force represents the strength of the intact repair composite and should be considered the strength of the tendon repair.
Dorsal Dupuytren’s Disease Causing A Swan-Neck Deformity
Authors: BOYCE D. E. , TONKIN M. A.
Published: August 2004

A previously undescribed lesion of Dupuytren’s disease is presented. An oblique cord coursed parallel to the oblique retinacular ligament of Landsmeer, but inserted proximal to the proximal interphalangeal joint, tethering the central slip and radial lateral band across the intervening transverse retinacular ligament. Contraction of this cord caused a rigid swan-neck deformity. Excision of the cord resulted in complete resolution of the deformity and a full range of motion in the affected digit.
Direct UHV-TEM Observation of Palladium Clusters on a Silicon Surface
Authors: Takeguchi Masaki , Mitsuishi Kazutaka , Tanaka Miyoko , Furuya Kazuo
Published: August 2004

About 1 monolayer of palladium was deposited onto a silicon (111) 7 × 7 surface at a temperature of about 550 K inside an ultrahigh vacuum transmission electron microscope, resulting in formation of Pd2Si nanoislands and a 1 × 1 surface layer. Pd clusters created from an excess of Pd atoms on the 1 × 1 surface layer were directly observed byin situplan view high-resolution transmission electron microscopy. When an objective aperture was introduced so that electron diffractions less than 0.20 nm were filtered out, the lattice structure of the 1 × 1 surface with 0.33 nm spacing and the Pd clusters with a trimer shape were visualized. It was found that image contrast of the 1 × 1 lattice on the specific height terraces disappeared, and thereby an atomic structure of the Pd clusters was clearly observed. The appearance and disappearance of the 1 × 1 lattice was explained by the effect of the kinematical diffraction. It was identified that a Pd cluster was composed of three Pd atoms without a centered Si atom, which is consistent with the model proposed previously. The feature of the Pd clusters stuck at the surface step was also described.
Off-Axis STEM or TEM Holography Combined with Four-Dimensional Diffraction Imaging
Authors: Cowley J.M.
Published: August 2004

Ultrahigh-resolution imaging may be achieved using modifications of the off-axis holography scheme in a scanning transmission electron microscopy (STEM) instrument equipped with one or more electrostatic biprisms in the illuminating system. The resolution is governed by the diameter of a reference beam, reduced by channeling through a line of atoms in an atomic-focuser crystal. Alternatively, the off-axis holography may be combined with the Rodenburg method in which a four-dimensional data set is obtained by recording a nanodiffraction pattern from each point of the specimen as the incident beams are scanned. An ultrahigh-resolution image is derived by computer processing to give a particular two-dimensional section of this data set. The large amount of data recording and data processing involved with this method may be avoided if the two-dimensional section is derived by recording the hologram while the four beams produced by two perpendicular biprisms are scanned in opposing directions across the specimen by varying the voltages on the biprisms. An equivalent scheme for conventional TEM is also possible. In each case, the complex transmission function of the specimen may be derived and resolutions of about 0.05 nm may be expected.
Advanced Electron Microscopy Characterization of Nanostructured Heterogeneous Catalysts
Authors: Liu Jingyue
Published: August 2004

Heterogeneous catalysis is one of the oldest nanosciences. Although model catalysts can be designed, synthesized, and, to a certain degree, characterized, industrial heterogeneous catalysts are often chemically and physically complex systems that have been developed through many years of catalytic art, technology, and science. The preparation of commercial catalysts is generally not well controlled and is often based on accumulated experiences. Catalyst characterization is thus critical to developing new catalysts with better activity, selectivity, and/or stability. Advanced electron microscopy, among many characterization techniques, can provide useful information for the fundamental understanding of heterogeneous catalysis and for guiding the development of industrial catalysts. In this article, we discuss the recent developments in applying advanced electron microscopy techniques to characterizing model and industrial heterogeneous catalysts. The importance of understanding the catalyst nanostructure and the challenges and opportunities of advanced electron microscopy in developing nanostructured catalysts are also discussed.
Physical Limits on Atomic Resolution
Authors: Van Dyck D. , Van Aert S. , den Dekker A.J.
Published: August 2004

It is shown that the ultimate resolution is not limited by the bandwidth of the microscope but by the bandwidth (i.e., the scattering power) of the object. In the case of a crystal oriented along a zone axis, the scattering is enhanced by the channeling of the electrons. However, if the object is aperiodic along the beam direction, the bandwidth is much more reduced. A particular challenge are the amorphous objects. For amorphous materials, the natural bandwidth is that of the single atom and of the order of 1 Å−1, which can be reached with the present generation of medium voltage microscopes without aberration correctors. A clear distinction is made between resolving a structure and refining, that is, between resolution and precision. In the case of an amorphous structure, the natural bandwidth also puts a limit on the number of atom coordinates that can be refined quantitatively. As a consequence, amorphous structures cannot be determined from one projection, but only by using atomic resolution tomography. Finally a theory of experiment design is presented that can be used to predict the optimal experimental setting or the best instrumental improvement. Using this approach it is suggested that the study of amorphous objects should be done at low accelerating voltage with correction of both spherical and chromatic aberration.
Zinc Lozenges: Cold Cure or Candy? Solution Chemistry Determinations
Authors: Eby George A.
Published: August 2004

Common colds were shortened by 7 days in a 1984 clinical trial using zinc gluconate throat lozenges each 2 h. Between then and 2004, 10 other double-blind, placebo-controlled clinical trials showed widely varying results. This re-analysis of these trials presents solution chemistry methods to elucidate differences in efficacy. Statistically significant correlation was shown between total daily dosages of positively charged zinc species and reductions in median (p = 0.005) and mean duration (p < 0.02) of common colds in these trials.