bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure–biological activity relationships in triterpenic saponins: the relative activity of protobassic acid and its derivatives against plant pathogenic fungi
Authors: Saha Supradip , Walia Suresh , Kumar Jitendra , Parmar Balraj S
Published: March 2010

BACKGROUND: Triterpenic saponins from Sapindus mukorossi Gaertn. and Diploknema butyracea JF Gmelin were evaluated for in vitro antifungal activity against four phytopathogenic fungi. The study of the structure–antifungal activity relationships of protobassic acid saponins was widened by including semi‐synthetic derivatives.

RESULTS: Diploknema butyracea saponins exhibited significant antifungal activity against three fungi (ED50 230–455 µg mL−1), whereas S. mukorossi saponin was effective against two fungi (ED50 181–407 µg mL−1). The n‐butanol extract after preparative HPLC separation provided two saponins from D. butyracea saponin mixture: 3‐O‐[β‐D‐glucopyarnosyl‐β‐D‐glucopyranosyl]‐16‐α‐hydroxyprotobassic acid‐28‐O‐[arabinopyranosyl‐glucopyranosyl‐xylopyranosyl]‐arabinopyranoside (MI‐I), and 3‐O‐β‐D‐glucopyranosyl‐glucopyranosyl‐glucopyranosyl‐16‐α‐hydroxyprotobassic acid‐28‐O‐[arabinopyranosyl‐xylopyranosyl‐arabinopyranosyl]‐apiofuranoside (MI‐III). The single saponin extracted from S. mukorossi saponin mixture was identified as 3‐O‐[O‐acetyl‐β‐D‐xylopyranosyl‐β‐D‐arabinopyranosyl‐β‐D‐rhamnopyranosyl] hederagenin‐28‐O[β‐D‐glucopyranosyl‐β‐D‐glucopyranosyl‐β‐D‐rhamnopyranosyl] ester (SM‐I). Monodesmosides resulting from the partial degradation of hederagenin and hydroxyprotobassic acid bisdesmosides exhibited significant reduction in antifungal effect. Further removal of sugar moiety yielded complete loss in activity. The antifungal activity of the triterpenic saponins was associated with their aglycone moieties, and esterification of the hydroxyl group led to change in antifungal activity.

CONCLUSION: Sapindus mukorossi saponin, which is effective against Rhizoctonia bataticola (Taub.) Briton Jones and Sclerotium rolfsii Sacc., can be exploited for the development of a natural fungicide. A sugar moiety is a prerequisite for the antifungal activity of triterpenic saponin. Copyright © 2010 Society of Chemical Industry
Sensitivities to DMI fungicides in populations of Podosphaera fusca in south central Spain
Authors: López‐Ruiz Francisco J , Pérez‐García Alejandro , Fernández‐Ortuño Dolores , Romero Diego , García Emilio , de Vicente Antonio , Brown James KM , Torés Juan A
Published: March 2010

BACKGROUND: Cucurbit powdery mildew elicited by Podosphaera fusca (Fr.) U Braun & N Shishkoff limits crop production in Spain. Disease control is largely dependent on fungicides such as sterol demethylation inhibitors (DMIs). Fungicide resistance is an increasing problem in this pathogen. To overcome such risk, it is necessary to design rational control programmes based upon knowledge of field resistance. The aim of this study was to investigate the state of DMI sensitivity of Spanish P. fusca populations and provide tools for improved disease management.

RESULTS: Using a leaf‐disc assay, sensitivity to fenarimol, myclobutanil and triadimenol of 50 isolates of P. fusca was analysed to determine discriminatory concentrations between sensitive and resistant isolates. As no clearly different groups of isolates could be identified, discriminatory concentrations were established on the basis of maximum fungicide field application rate, 100 mg L−1 for the three fungicides tested. Subsequently, a survey of DMI resistance was carried out in different provinces located in the south central area of Spain during the cucurbit growing seasons in 2002, 2003 and 2004. Examination of a collection of 250 isolates revealed that 23% were resistant to fenarimol and 7% to triadimenol, the provinces of Almería, Badajoz and Murcia being the locations with the highest frequencies of resistance. By contrast, no resistance to myclobutanil was found.

CONCLUSION: Results show that fenarimol and, to a lesser extent, triadimenol have become less efficient for controlling cucurbit powdery mildew in Spain. These are important observations that should lead to reconsideration of the current disease management programmes. Copyright © 2010 Society of Chemical Industry
Atomic interactions and hydrogen‐induced γ* phase in fcc iron–nickel alloys
Authors: Movchan D. N. , Shyvanyuk V. N. , Shanina B. D. , Gavriljuk V. G.
Published: March 2010

Energy of metal–metal (Me–Me) and metal–hydrogen (Me–H) bonds in hydrogen‐free and hydrogen‐charged fcc iron, nickel, and iron–nickel alloys are ab initio calculated. It is shown that short‐range decomposition of Fe–Ni solid solution and difference in Fe–H and Ni–H bonds are responsible for splitting of γ reflections in the X‐ray diffraction patterns, which is at variance with the common interpretation in terms of a hydrogen‐caused γ* phase. X‐ray diffraction measurements confirm the absence of miscibility gap in the FeNi–H solid solution and its occurrence in Ni–H. Results of calculations are consistent with the absence of H–H pairs in pure nickel.
Inhomogeneities of InGaN/GaN MOVPE multi quantum wells grown with a two temperatures process studied by transmission electron microscopy
Authors: Kret S. , Ivaldi F. , Sobczak K. , Czernecki R. , Leszczyński M.
Published: March 2010

The structural investigation of InGaN/GaN:Si multiple quantum well (MQW) samples grown by low‐pressure metal‐organic vapor phase epitaxy (LP‐MOVPE) in a two temperatures (2T) process on high‐pressure GaN mono‐crystalline substrates is performed by transmission electron microscopy (TEM). A sample in which barriers and wells were grown at 780 °C is compared with another in which the barriers were deposited at 900 °C and the wells at 730 °C. For both samples the indium composition in the QWs reaches the level of about 20 at.%. The local indium composition was measured through strain measurements by digital processing from the lattice fringes images taken by TEM. Cross‐sectional investigations are performed in two zone axes – [$1\bar {1}00$] and [$11\bar {2}0$] – with the use of axial and off‐axis illumination. During TEM investigations the formation of “false indium clusters ” of the size of 2–4 nm was observed for both samples just after 2 min of LaB6 electron beam illumination at 200 kV. Large lateral fluctuations of indium content in the QWs of the length of 30–130 nm were detected in 2T sample. The plan view analysis was carried out to characterize the anisotropy of the indium fluctuation inside the QWs.
In‐vacancies in Si‐doped InN
Authors: Rauch C. , Reurings F. , Tuomisto F. , Veal T. D. , McConville C. F. , Lu H. , Schaff W. J. , Gallinat C. S. , Koblmüller G. , Speck J. S. , Egger W. , Löwe B. , Ravelli L. , Sojak S.
Published: March 2010

The introduction of vacancy type point defects by Si doping in InN grown by plasma‐assisted molecular beam epitaxy was studied using a monoenergetic positron beam. With the combination of positron lifetime and Doppler broadening measurements, compensating In‐vacancy (VIn) acceptors were identified in the material. For increasing Si doping an enhanced formation of VIn defects was observed, up to a concentration of $c_{\rm V} = 7 \times 10^{17} \,{\rm cm}^{ - 3} $ in the highest doped sample ($n_{\rm e} = 6.6 \times 10^{20} \,{\rm cm}^{ - 3} $). A strong inhomogeneity of the defect profile with a significant increase of the VIn concentration toward the layer/substrate interface could be detected. Additionally, larger vacancy clusters containing several VIn are formed in the proximity of the interface.
A study on oxygen reduction inhibition at pyridine‐terminated self assembled monolayer modified Au(111) electrodes
Authors: Muglali Mutlu Iskender , Bashir Asif , Rohwerder Michael
Published: March 2010

The electroreduction of oxygen on self‐assembled monolayers (SAMs) of various pyridinedisulfides and pyridinethiols on Au(111) surfaces has been investigated in alkaline solutions. Electrochemical experiments that were carried out in three‐electrode cell reveal a good correlation between the chain‐length of thiol molecules and the oxygen reduction inhibition of the resulting adlayer films. The effect of retarded diffusion of oxygen through the protective film has been investigated by forming additional layer of immobilized cytochrome c (cyt.c) metalloprotein on pyridine moiety during linear sweep voltammetry (LSV) scans. At sufficiently negative cathodic potentials the electrochemical reaction rate has been observed to increase together with the density of defects. Morphological changes at different levels of cathodic polarization were investigated by ex situ scanning tunneling microscopy (STM), indicating oxygen reduction reaction (ORR) induced structural defects at the metallorganic interface.
Theory of carrier and photon dynamics in quantum dot light emitters
Authors: Dachner Matthias‐René , Malic Ermin , Richter Marten , Carmele Alexander , Kabuss Julia , Wilms Alexander , Kim Jeong‐Eun , Hartmann Gregor , Wolters Janik , Bandelow Uwe , Knorr Andreas
Published: March 2010

We present a microscopic theory describing the charge carrier and light emission dynamics in quantum dot (QD) light emitters. The theory covers non‐classical light emission (fluorescence and Raman emission) in the low carrier injection limit as well as laser emission and pulse amplification in the high carrier injection limit. The theoretical approach is based on QD Bloch equations including microscopically calculated Coulomb and electron–phonon scattering rates between bound QD, continuous wetting layer (WL) and bulk states. In the low carrier density limit, multi‐phonon relaxation is the dominant process, while at high charge carrier densities, Coulomb scattering dominates the dynamics. Using an equation of motion approach, we address (i) time‐resolved fluorescence and Raman emission, (ii) electrical injection and charge carrier transfer from bulk into WL and QD states, (iii) single photon emission and (iv) gain dynamics of QD amplifiers and lasing dynamics in QD vertical‐cavity surface‐emitting lasers (VCSELs) at high injection currents.
Near‐field scanning optical microscopy of colloidal CdSe nanowires
Authors: Mintairov Alexander M. , Herzog Joseph , Kuno Masaru , Merz James L.
Published: March 2010

We have developed a nano‐optical technique using diffraction‐limited far‐field fluorescence monitoring of near‐field scanning optical microscopy (NSOM) experiments. The technique was combined with time‐resolved (TR) spectroscopy and was used to study the emission properties of single colloidal CdSe nanowires (NWs) with spatial resolution ∼100 nm. The use of this novel technique reveals a critical role of organic suspensions in optical experiments with single colloidal nanostructures. We observed that organic suspensions form a viscous shell which acts as a nano‐lens providing efficient coupling of excited and emitted photons to the NW. We demonstrate that physical distortion of the shell produced by the near‐field probe affects the emission dynamics of single NWs. Temperature dependent measurements show that the emission decay of a colloidal NW is dominated by size‐dependent non‐radiative recombination.
Self‐organized nucleation layer for the formation of ordered arrays of double‐walled TiO2 nanotubes with temperature controlled inner diameter
Authors: Enachi Mihai , Tiginyanu Ion , Sprincean Veaceslav , Ursaki Veaceslav
Published: March 2010

It is proposed to use the variation of the electrolyte temperature to fabricate titania nanotubes with variable inner diameter at a constant outer diameter and an invariable package density. The anodization of Ti sheets in an ethylene glycol and HF containing electrolyte is found to allow the preparation of nanotubes with the inner diameter controlled in the range from 10 nm to more than 250 nm through the change of the electrolyte temperature from –20 °C to +50 °C. The peculiarities of the anodization process performed at low electrolyte temperatures are discussed.

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(© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of phosphorus, arsenic or antimony ion implantation in silicon targets
Authors: Labbani R.
Published: March 2010

The aim of this work was to study the behaviors of P+, As+ and Sb+ ions implanted in silicon targets. The investigation was mainly performed by simulation using the SRIM2006 (stopping and range of ions in matter) program. Several quantities, such as the depth profiles of the ion concentration, stopping powers and radiation damage, were predicted. Besides, an experimental study was carried out particularly for the case of Sb+ ions. The antimony ion implantation was performed to a dose of 5 × 1015 Sb+ cm−2 at 120 keV energy into an Si(100) target. The samples were analyzed by means of Rutherford backscattering spectroscopy (RBS) using He+ particles. A discrepancy between the experimental and simulated antimony depth profiles was revealed. In the case of phosphorus and arsenic, the simulated projected ranges (Rps) were compared with literature values and good agreement has been obtained. Finally, it is necessary to note that the predictions of some effects related to ion implantation (annealing temperature, crystallographic orientation of the targets, multi‐implantations, etc.) are not possible via the SRIM code. Copyright © 2010 John Wiley & Sons, Ltd.
Observation of self‐assembled monolayers on diamond‐like carbon films: agglomeration of self‐assembled FDTS molecules
Authors: Choi Junho , Sakurai Kenichi , Kato Takahisa
Published: March 2010

Self‐assembled monolayers (SAMs) of 1H,1H,2H,2H‐perfluorodecyltrichlorosilane (FDTS) were prepared on hydrogen‐free diamond‐like carbon (DLC) films by immersing the DLC substrates into dilute solutions of FDTS in hydrofluoroether. The FDTS‐adsorbed DLC surfaces were observed using a tapping mode atomic force microscopy (AFM) with respect to the immersion time to investigate the monolayer formation process. The measurements of the water contact angles, X‐ray photoelectron spectroscopy (XPS) and the surface roughness were also conducted. The DLC films were deposited on silicon plates with an electron cyclotron resonance(ECR)‐type ion beam sputter using graphite as a sputter target. Initially, FDTS molecules form a liquid‐like disordered mass of molecules on the DLC surface, and then begin to form densely packed FDTS islands with the height of a monolayer. The FDTS monolayer islands grow laterally with the immersion time. After immersion for several hours, the agglomeration of FDTS molecules to a height of 3–5 nm is observed on the DLC surfaces. This is due to the presence of a large number of active sites on the hydrogen‐free DLC surface, preventing the surface diffusion of FDTS molecules. Also, the inhomogeneity of the DLC surface due to the adsorption of a large number of oxygen atoms from the air after DLC deposition is one of the reasons for the FDTS agglomeration. Copyright © 2010 John Wiley & Sons, Ltd.
Photoelectrochemical and photocatalytic properties of mesoporous TiO2 films modified with silver and gold nanoparticles
Authors: Smirnova N. , Vorobets V. , Linnik O. , Manuilov E. , Kolbasov G. , Eremenko A.
Published: March 2010

TiO2 and Zn2+/TiO2 functional coatings doped with Ag or Au nanoparticles were prepared by photo‐ or thermoreduction of metal ions introduced into bulk or adsorbed on the film surface. TiO2 and Zn2+/TiO2 films with the Ag or Au nanoparticles (MNPs) distributed in the matrix and on the surface were characterized by XRD, TEM and UV‐Vis spectroscopy. Direct photoelectrochemical investigations of the M/TiO2 and M/Zn2+/TiO2 heterojunctions showed the cathodic shift of the flatband potential position and the increase of photocurrent quantum yield in comparison with unmodified TiO2 electrodes. Photocatalytic activity of synthesized films estimated in the process of degradation of the antibiotic tetracycline hydrochloride coincides with photoelectrochemical data. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of pH variation in aqueous solutions on dissolution of copper oxide
Authors: Ko Cheon Kwang , Lee Won Gyu
Published: March 2010

Dissolution characteristics, such as the solubility of copper oxides and the complexation stability between copper ions and aqueous solutions, were analyzed under various pH values of citric acid or monoethanolamine (MEA) aqueous solution, which are known as complexing agents for copper. The dissolution characteristics of the aqueous solutions were measured in terms of the solubility of copper oxides and metallic copper. The citric acid solution had a good solvent property for copper oxides in the range of acidic conditions, whereas the MEA solution showed the same property in the basic region. The surface roughness of copper film treated with solutions having different pH values strongly depended on the solubility of copper oxides. The treatment of citric acid and MEA of different pH values has an influence on the oxidation status of copper surface, which is confirmed with X‐ray photoemission spectroscopy and electrochemical impedance. Copyright © 2010 John Wiley & Sons, Ltd.
Microstructural surface changes of electrodeposited Pb on gas diffusion electrode during electroreduction of gas‐phase CO2
Authors: Machunda Revocatus L. , Lee JongGyu , Lee Jaeyoung
Published: March 2010

We have applied zero‐gap cell for gas‐phase CO2 conversion to introduce better applicability at large scale. The cathodic reduction of CO2 has attracted considerable attention with the aim of generating useful fuels and chemicals. The CO2 gas is reduced on the surface of the electrodeposited Pb on gas diffusion electrode to give mainly formic acid, accompanied by morphological and crystalline changes of the catalyst. These changes are revealed by both scanning electron microscope and X‐ray diffraction analysis. The catalytic conversion of CO2 gas as a function of Pb microstructures in relation to formic acid production was also investigated and is presented. Copyright © 2010 John Wiley & Sons, Ltd.
Formation of multi‐layered inorganic film on polycarbonate surface modified by an atmospheric plasma discharge
Authors: Won Dong Su , Kim Tea Kyung , Lee Won Gyu
Published: March 2010

Surface modification of polymers has been widely studied because of the industrial interest in several applications involving adhesion, packaging and metallization, among others. Plasma treatment, particularly atmospheric pressure plasma, is one of the most versatile techniques in surface modification. In this work, atmospheric pressure plasma treatment was performed to modify a polycarbonate surface. The effects of the treatment were sensitive to both the plasma ambient and the time elapsed after treatment. Surface treatment with a dielectric barrier discharge plasma torch produced an increase in the wettability of polycarbonate through the creation of COH polar groups on its surface, together with surface roughness. These effects were more pronounced by the addition of oxygen in an Ar gas mixture and the surface treatment time. In general, the atmospheric plasma torch treatment helped to enhance the wettability of the aqueous solutions to form a multi‐layered inorganic film on the polycarbonate. Copyright © 2010 John Wiley & Sons, Ltd.
Temperature‐dependent profile of the surface states and series resistance in (Ni/Au)/ AlGaN/AlN/GaN heterostructures
Authors: Taşçıoǧlu İ. , Aydemir U. , Şafak Y. , Özbay E.
Published: March 2010

The profile of the interface state densities (Nss) and series resistances (Rs) effect on capacitance–voltage (C–V) and conductance‐voltage (G/ω–V) of (Ni/Au)/AlxGa1−xN/AlN/GaN heterostructures as a function of the temperature have been investigated at 1 MHz. The admittance method allows us to obtain the parameters characterizing the metal/semiconductor interface phenomena as well as the bulk phenomena. The method revealed that the density of interface states decreases with increasing temperature. Such a behavior of Nss can be attributed to reordering and restructure of surface charges. The value of series Rs decreases with decreasing temperature. This behavior of Rs is in obvious disagreement with that reported in the literature. It is found that the Nss and Rs of the structure are important parameters that strongly influence the electrical parameters of (Ni/Au)/AlxGa1−xN/AlN/GaN(x = 0.22) heterostructures. In addition, in the forward bias region a negative contribution to the capacitance C has been observed, that decreases with the increasing temperature. Copyright © 2010 John Wiley & Sons, Ltd.
A comparative X‐ray photoelectron spectroscopy and medium‐energy ion‐scattering study of ultra‐thin, Hf‐based high‐k films
Authors: Sygellou L. , Ladas S. , Reading M. A. , van den Berg J. A. , Conard T. , De Gendt S.
Published: March 2010

Ultra‐thin high‐k layers based on HfO2, or Hf‐silicates in combination with sub‐nanometer SiO2, show much promise in their use as Si‐compatible gate dielectrics. XPS has been applied on a range of HfO2/SiO2 and HfSiOx(60%Hf)/SiO2 films on Si(100), before and after decoupled plasma nitridation (DPN) at 1073 K. The treatment of the data was optimized in order to determine individual layer thicknesses of the multilayer stack taking into account the measured nitrogen content of the nitrided films. The procedure adhered to the prescriptions of ISO18118:2004(E) for the calculations of inelastic mean free paths (IMFP) and elastic corrections thereof, using film material properties, like densities and band gaps. Effective attenuation lengths (EAL) were taken throughout as 90% of the respective IMFP, whereas an appropriate set of empirical relative sensitivity factors (RSF) was used. The XPS‐derived thicknesses were compared with corresponding values obtained from medium‐energy ion scattering (MEIS) measurements on the same series of specimens in combination with energy spectrum simulation to provide quantitative layer information with sub‐nanometer resolution. The XPS and MEIS results exhibit very good agreement on the deduced layer structures within the respective experimental uncertainty, and both sets are consistent with the grown nominal layer parameters of the high‐k nanofilms. Copyright © 2010 John Wiley & Sons, Ltd.
XPS depth profiling of polystyrene etched by electrospray droplet impact
Authors: Sakai Yuji , Iijima Yoshitoki , Asakawa Daiki , Hiraoka Kenzo
Published: March 2010

The molecular‐level depth profiling of polystyrene (PS) has been performed by using a newly designed electrospray droplet impact (EDI) gun. The multiple charged water droplets with kinetic energy of ∼106 eV were irradiated to a bulk and a spin‐coated PS. When a PS target is etched by EDI, the ablation of the sample is suppressed to minimal, i.e. the shallow surface etching with nonrecognizable damage on the surface is realized. It was found that XPS spectra for PS were independent on the irradiation time by EDI. This indicates that EDI is a unique technique for the surface etching of synthetic polymer materials without resulting in any damage to the etched surface. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of different P/As ratio on the optical and structural properties of GaAs1−xPx/GaAs
Authors: Cetin Saime S. , Kinaci Baris , Asar Tarık , Kars Ilknur , Ozturk Mustafa K. , Mammadov Tofig S. , Ozcelik Suleyman
Published: March 2010

The GaAs1−xPx/GaAs ternary alloys were grown on n‐GaAs (100) substrate with different P/As flux ratio by solid source molecular beam epitaxy (MBE) system using GaP decomposition source. In order to obtain smooth interface and lattice mismatch structures we have used both continuous growth (CG) and graded growth (GG) methods. The range of lattice parameters in the graded epilayer and phosphorous composition in the samples were determined by the high‐resolution X‐ray diffraction (HRXRD) rocking curve simulation. The critical energy points of the interband transition edges of the structures were determined by line‐shape analyses on their dielectric functions (DF) using spectroscopic ellipsometry (SE) measurements at a room temperature in the 0.5–5 eV photon energy region. Also, surface and interface phenomenon of the structures were discussed by using ellipsometric data. Phosphorous compositions of the ternary alloys were also calculated by photoluminescence (PL) emission peak positions at room temperature and using the bowing parameter obtained by fitting to critical points. Copyright © 2010 John Wiley & Sons, Ltd.
Probing soft materials with energetic ions and molecules: from microscopic models to the real world
Authors: Delcorte A. , Bertrand P. , Garrison B. J. , Hamraoui K. , Mouhib T. , Restrepo O. A. , Santos C. N. , Yunus S.
Published: March 2010

After introducing a typical example of the performance of C60 clusters for the molecular depth‐profiling analysis of (bio‐)organic samples by secondary ion mass spectrometry (SIMS), this contribution reviews a few areas in which microscopic models using molecular dynamics (MD) simulations provide a better understanding and predictions in the field of organic sample sputtering. The topics considered discuss about structural effects in crystalline hydrocarbons, the sputtering of hybrid metal–organic surfaces and the influence of the cluster projectile size on molecular desorption and fragmentation. The next section of the article presents experimental studies using real‐world samples taken from technological applications in materials science to illustrate some of the strengths and weaknesses of molecular analysis and imaging of organic and biological samples by SIMS. Connections with the results of the simulations are pointed out when it is deemed appropriate. Copyright © 2010 John Wiley & Sons, Ltd.
Angular distribution of liquid droplets during the laser ablation of silicon target
Authors: Belaroussi Y. , Kerdja T. , Malek S.
Published: March 2010

Pulsed laser deposition of thin films involves an extremely complex process, and therefore, the study of the different aspects of the basic mechanism of laser ablation is still under investigation and development.

In this work, the initial stages of laser ablation process have been studied by considering the roughness of the deposited surfaces, their continuous morphological changes and the angular distribution of liquid droplets produced by laser irradiation.

Various experiments on silicon wafers, using a KrF excimer laser (248 nm) impinging at 45° with respect to the target were performed. Scanning electron microscopy technique was used to investigate the morphological changes of the silicon surface and the angular emission distribution of the liquid droplets. Copyright © 2010 John Wiley & Sons, Ltd.
Auger electron spectroscopy and X‐ray photoelectron spectroscopy study of the electron‐stimulated surface chemical reaction mechanism for phosphor degradation
Authors: Swart H. C. , Terblans J. J. , Coetsee E. , Kumar Vinay , Ntwaeaborwa O. M. , Dhlamini M. S. , Dolo J. J.
Published: March 2010

Phosphors normally lose brightness upon bombardment with electron, ion or photon beams. A combination of techniques such as X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and cathodoluminescence (CL) spectroscopy was used to show that the main reason for the degradation in luminescent intensity under electron bombardment is the formation of a non‐luminescent layer on the surface due to an electron‐stimulated surface chemical reaction (ESSCR). The decrease in luminance was found to be a result of the growth of the ‘dead layer’. Different phosphors which include sulfide‐based as well as oxide‐based phosphors reacted similarly under electron bombardment. The formation of an altered layer (oxide layer) on the surface of the different phosphors leads to the decrease of the luminescent intensity at that specific wavelength and in some cases to an increase of the intensity at another wavelength. The mechanisms of the degradation of several rare earth and transition metal phosphors are discussed in detail. Copyright © 2010 John Wiley & Sons, Ltd.
Investigating the surface properties of polymer‐coated clay by IGC
Authors: Topaloǧlu Yazıcı Demet
Published: March 2010

This paper deals with understanding the surface behaviors of calcined clay and the organic/inorganic system. The surface properties like the adsorption thermodynamic parameters and the dispersive component of the surface energy were determined by the adsorption of n‐alkanes on the solids that were the subject of interest, i.e. calcined sepiolite and polystyrene coated calcined sepiolite. Inverse gas chromatography (IGC) was used for this purpose. The dispersive component of the surface energy of system lies between the members of system. Additionally Diffuse Reflectance Infrared Fourier Transform (DRIFT) technique was used to record the functional groups of solids. Copyright © 2010 John Wiley & Sons, Ltd.
Non‐destructive investigation of fibronectin adsorption on titanium surfaces using PM‐RAIRS: effect of surface hydroxylation
Authors: Boudesocque Stéphanie , Dargaud Olivier , Stievano Lorenzo , Méthivier Christophe , Lambert Jean‐François , Coradin Thibaud , Pradier Claire‐Marie
Published: March 2010

Polarisation‐modulation reflection‐absorption infrared spectroscopy (PM‐RAIRS) is a useful non‐destructive technique to study semi‐quantitatively the adsorption of proteins on metal surfaces. In this work, we employed PM‐RAIRS to study the effect of the degree of hydroxylation of the surface of titanium metal sheets, obtained by specific acidic or basic treatments, on the adsorption of fibronectin, a model plasma adhesion protein. Our results seem to indicate that the degree of hydroxylation does not influence significantly the adhesion properties of fibronectin, which is one of the main steps in titanium osseointegration process. Copyright © 2010 John Wiley & Sons, Ltd.
Comparison of surface activation processes for protein immobilization on plasma‐polymerized acrylic acid films
Authors: Strola S. , Ceccone G. , Gilliand D. , Valsesia A. , Lisboa P. , Rossi F.
Published: March 2010

In this work, quartz crystal microbalance (QCM) crystal surfaces were analyzed in order to study the behavior of protein attachment on fouling substrates. In this context, covalent and noncovalent immobilization of different proteins [bovine serum albumin (BSA), collagen] has been investigated. For the noncovalent immobilization, silicon dioxide‐coated QCM crystals were used, while the covalent immobilization was obtained via plasma‐polymerized acrylic acid film (ppAA) deposited onto the QCM substrates. Two different activation processes, namely, reaction with trifluoroacetic anhydride (TFAA) and 1‐ethyl‐3,3‐dimethyl carbodiimide (EDC) and N‐hydroxysuccinimide (NHS), were studied.

After the QCM experiments, all samples were analyzed with X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry to gain information on the surface chemistry and composition. The results indicate that the protein adsorption process depends on protein concentration, whereas the complement activation effectiveness depends on protein type. In particular, for BSA, XPS and QCM data show a greater immobilization in the case of EDC/NHS activation compared to the TFAA, whereas in the case of collagen, only the EDC/NHS activation was able to yield covalent coupling. Copyright © 2010 John Wiley & Sons, Ltd.
First‐principle studies of dissociative adsorption of H2O on NiAl(110)‐(2 × 2) surface
Authors: Evecen M. , Çakmak M.
Published: March 2010

A theoretical study of the interaction of H2O with NiAl(110) surface has been carried out with density functional theory. We have studied that H2O molecule dissociates into OH and H on NiAl(110). We have assumed four possible locations for OH and H on the NiAl(110) surface. The minimum energy for OH molecule and H atom is at the 2AlNi site, but H atom towards a near by surface Ni atom, with the adsorption energy −0.79 eV. Bond length and bond angle of H2O molecule were found to be 0.99 Å and 103.9°, respectively, which are close to gas phase theoretical (exp.) values 0.97 Å (0.96 Å) and 104.8° (104.5° ). The calculated bond length between O and Al (H) is 1.97 Å (0.98 Å). Bond length between H and Ni is found to be 1.55 Å. We have also presented the reaction path for OHH on NiAl(110) surface. Copyright © 2010 John Wiley & Sons, Ltd.
The effect of temperature on interfacial characteristics of fiber cord/rubber composite in the pull‐out process
Authors: Fang Qing‐Hong , Wang Hui‐Bin , Huang Bao‐Zong
Published: March 2010

The test of fiber pullout from rubber was carried out under different conditions, at three temperatures. Based on the experiment and a nonlinear two‐dimensional finite element (2D FE) modeling, the single fiber cord pullout from the rubber matrix at different temperatures was analyzed. The changes of interfacial shear stresses and failure mode at every stage of interface cracking forthe fiber cord/rubber composite were also investigated. It is shown that the simulation results of the pullout are in good agreement with the experiment. It is concluded that the 2D FE modeling can effectively predict the thermal interface cracking process for an axisymmetric structure of the fiber cord/rubber composite. Copyright © 2010 John Wiley & Sons, Ltd.
Determination of atomic Ni interaction with TiO2 by XPS
Authors: Pan J. S. , Tao J. G. , Huan C. H. A. , Chiam S. Y. , Zhang Z. , Li D. T. H. , Sun Y. , Chai J. W. , Wang S. J. , Sun Chang Q.
Published: March 2010

It is impossible to directly measure the photoelectron spectrum of an atom using conventional XPS due to its low detection sensitivity. In this work, an indirect method has been developed to determine the binding energy (BE) of an atom. In this method, the BE of the atom can be obtained by extrapolation of the experimental BE curves with atomic deposition coverage to zero coverage. With this method, the Ni 2p3/2 BE's of atomic Ni on TiO2(001) and (110) surfaces are deduced to be 853.69 and 853.55 eV, respectively. Compared with atomic Ni in gas phase, relaxation shifts of 7.34 and 7.48 eV are obtained on TiO2(001) and (110) surfaces, respectively. These values are very close to the relaxation shift of 7.3 eV due to d electron screening, indicating d‐like screening effects from the TiO2 substrates after Ni 2p photoionization. This method is also used to determinate the Ni 2p3/2 BE's of atomic Ni on TiO2(001) with different surface stoichiometries. The difference of Ni 2p3/2 BE is due to different interfacial charge transfer. Copyright © 2010 John Wiley & Sons, Ltd.
A Bayesian approach to competing risks analysis with masked cause of death
Authors: Sen Ananda , Banerjee Mousumi , Li Yun , Noone Anne‐Michelle
Published: March 2010

Cause‐specific analyses under a competing risks framework have received considerable attention in the statistical literature. Such analyses are useful for comparing mortality patterns across racial and/or age groups. Earlier work in the statistical literature focused on the situation when the cause of death is known. A challenging twist to the problem arises when the cause of death is not known exactly, but can be narrowed down to a set of potential causes that do not necessarily act independently. This phenomenon, referred to asmasking, is often the result of incomplete or partial information on death certificates and/or lack of routine autopsy on every patient. In this article we propose a semiparametric Bayesian approach for analyzing competing risks survival data with masked cause of death. The models proposed do not assume independence among the causes, and are valid for an arbitrary number of causes. Further, the Bayesian approach is flexible in allowing a general pattern of missingness for the cause of death. We illustrate our methodology using breast cancer data from the Detroit Surveillance, Epidemiology, and End Results registry. Copyright © 2010 John Wiley & Sons, Ltd.
Approximate inference for disease mapping with sparse Gaussian processes
Authors: Vanhatalo Jarno , Pietiläinen Ville , Vehtari Aki
Published: March 2010

Gaussian process (GP) models are widely used in disease mapping as they provide a natural framework for modeling spatial correlations. Their challenges, however, lie in computational burden and memory requirements. In disease mapping models, the other difficulty is inference, which is analytically intractable due to the non‐Gaussian observation model. In this paper, we address both these challenges. We show how to efficiently build fully and partially independent conditional (FIC/PIC) sparse approximations for the GP in two‐dimensional surface, and how to conduct approximate inference using expectation propagation (EP) algorithm and Laplace approximation (LA). We also propose to combine FIC with a compactly supported covariance function to construct a computationally efficient additive model that can model long and short length‐scale spatial correlations simultaneously. The benefit of these approximations is computational. The sparse GPs speed up the computations and reduce the memory requirements. The posterior inference via EP and Laplace approximation is much faster and is practically as accurate as via Markov chain Monte Carlo. Copyright © 2010 John Wiley & Sons, Ltd.
Radiosynthesis of the candidate β‐amyloid radioligand [11C]AZD2184: Positron emission tomography examination and metabolite analysis in cynomolgus monkeys
Authors: Andersson Jan D. , Varnäs Katarina , Cselényi Zsolt , Gulyás Balázs , Wensbo David , Finnema Sjoerd J. , Swahn Britt‐Marie , Svensson Samuel , Nyberg Svante , Farde Lars , Halldin Christer
Published: March 2010

β‐Amyloid accumulation is associated with the pathogenesis of Alzheimer's disease (AD). AZD2184, a new radioligand for high‐contrast positron emission tomography (PET) imaging of Aβ‐deposits, has recently been developed and characterized in vitro and in rodents ex vivo. The objective of this study was to label AZD2184 with carbon‐11, to perform in vivo characterization of [11C]AZD2184 ([11C]5) in the cynomolgus monkey brain as well as whole‐body dosimetry, and to examine the metabolism of the labeled radioligand. [11C]5 was prepared by a two‐step radiosynthesis starting with the reaction of 5‐(6‐(tert‐butyldimethylsilyloxy)benzo[d]thiazol‐2‐yl)pyridin‐2‐amine with [11C]methyl iodide followed by deprotection using water. Four brain PET measurements in two cynomolgus monkeys and one whole‐body PET measurement were performed with [11C]5. There was a high and rapid brain uptake (2.2–3.4% of injected dose at 2 min). The distribution of brain radioactivity was fairly uniform, with early to late‐brain concentration ratios (peak vs. 60 min) higher for [11C]5 than ratios previously reported for [11C]PIB (8.2 and 4.6, respectively). Based on the whole‐body data, it was estimated that an effective dose in an adult male would be 6.2 μSv/MBq and thus would be safe from a radiation point of view for multiple scans within the same year. [11C]5 shows binding characteristics, suggesting low levels of white‐matter retention, and may thus provide improved contrast when compared with currently used PET radioligands for visualization of Aβ‐deposits. On the basis of the labeling chemistry and the results of the biological evaluation, we conclude that [11C]5 should be useful for routine clinical studies. Synapse 64:733–741, 2010. © 2010 Wiley‐Liss, Inc.
(+)‐Methamphetamine‐induced monoamine reductions and impaired egocentric learning in adrenalectomized rats is independent of hyperthermia
Authors: Herring Nicole R. , Gudelsky Gary A. , Vorhees Charles V. , Williams Michael T.
Published: March 2010

Methamphetamine (MA) is widely abused and implicated in residual cognitive deficits. In rats, increases in plasma corticosterone and egocentric learning deficits are observed after a 1‐day binge regimen of MA (10 mg/kg × 4 at 2‐h intervals). The purpose of this experiment was to determine if adrenal inactivation during and following MA exposure would attenuate the egocentric learning deficits in the Cincinnati water maze (CWM). In the first experiment, the effects of adrenalectomy (ADX) or sham surgery (SHAM) on MA‐induced neurotoxicity at 72 h were determined. SHAM‐MA animals showed typical patterns of hyperthermia, whereas ADX‐MA animals were normothermic. Both SHAM‐MA‐ and ADX‐MA‐treated animals showed increased neostriatal glial fibrillary acidic protein and decreased monoamines in the neostriatum, hippocampus, and entorhinal cortex. In the second experiment, SHAM‐MA‐ and ADX‐MA‐treated groups showed equivalently impaired CWM performance 2 weeks post‐treatment (increased latencies, errors, and start returns) compared to SHAM‐saline (SAL) and ADX‐SAL groups with no effects on novel object recognition, elevated zero maze, or acoustic startle/prepulse inhibition. Post‐testing, monoamine levels remained decreased in both MA‐treated groups in all three brain regions, but were not as large as those observed at 72‐h post‐treatment. The data demonstrate that MA‐induced learning deficits can be dissociated from drug‐induced increases in plasma corticosterone or hyperthermia, but co‐occur with dopamine and serotonin reductions. Synapse 64:773–785, 2010. © 2010 Wiley‐Liss, Inc.
Different chronic cocaine administration protocols induce changes on dentate gyrus plasticity and hippocampal dependent behavior
Authors: Perez M.F. , Gabach L.A. , Almiron R.S. , Carlini V.P. , De Barioglio S.R. , Ramirez O.A.
Published: March 2010

Hippocampus is a limbic structure that participates in learning and memory formation. Specifically the dentate gyrus has been described as a hippocampal subregion with high rates of plasticity and it is targeted by different psychoactive drugs modulating synaptic plasticity. Repeated cocaine administration induces sensitization to the locomotor effects and it is believed that sensitization involves the same mechanisms of drug seeking and relapse. Although, the mechanisms underlying sensitization is not fully understood. In this work we investigated the impact of repeated intraperitoneal administration of cocaine (15 or 20 mg/kg/day along 5 or 15 days respectively; and 15 mg/kg/day along 5 day followed by a challenge dose after three days of withdrawal) on the dentate gyrus synaptic plasticity, differentiating between sensitized and nonsensitized rats. Furthermore, we correlated changes on the hippocampal synaptic plasticity to memory retention. Our results revealed that the prevalence of cocaine sensitization (around 50%) was identical in all protocols used. The results found in the threshold to generate LTP were similar for all protocols used, being the threshold values cocaine‐treated groups (sensitized and nonsensitized) significantly reduced compared to controls, observing the highest reduction in the sensitized group. Moreover, we observed a facilitated retention of recent memory formation only in sensitized animals the nonsensitized subjects remained at the control levels. In conclusion, sensitization to cocaine generates a high efficiency of hippocampal synaptic plasticity that may underlie the aberrant engagement of learning processes occurred during drug addiction. Synapse 64:742–753, 2010. © 2010 Wiley‐Liss, Inc.
Hypogonadism: an underdiagnosed condition
Authors: Muneer Asif
Published: March 2010

Hypogonadism, or male testosterone deficiency, is an underdiagnosed syndrome that, with its links to age, obesity, type 2 diabetes and metabolic syndrome, is becoming increasingly relevant. The author outlines the presentation, diagnosis and treatment options. Copyright © 2010 Wiley Interface Ltd
Care pathways for patients with breast cancer
Authors: Pittathankal Antony , Davidson Tim
Published: March 2010

Although the incidence of breast cancer is increasing in the UK, mortality is decreasing thanks to significant achievements in the organisation and delivery of breast cancer care, with multidisciplinary working at its centre. Copyright © 2010 Wiley Interface Ltd
Stability analysis of the tip vortices of a wind turbine
Authors: Ivanell Stefan , Mikkelsen Robert , Sørensen Jens N. , Henningson Dan
Published: March 2010

The aim of the present paper is to obtain a better understanding of the stability properties of wakes generated by wind turbine rotors. To accomplish this, a numerical study on the stability of the tip vortices of the Tjaereborg wind turbine has been carried out. The numerical model is based on large eddy simulations of the Navier–Stokes equations using the actuator line method to generate the wake and the tip vortices. To determine critical frequencies, the flow is disturbed by inserting harmonic perturbations, giving rise to spatially developing instabilities. The results show that the instability is dispersive and that growth arises only for some specific frequencies and type of modes, in agreement with previous instability studies. The result indicates two types of modes; one where oscillations of neighboring vortex spirals are out of phase and one where oscillations in every vortex spiral in phase. The mode with spirals out of phase results in the largest growth with the main extension of the disturbance waves in radial and downstream directions. The out‐of‐phase disturbance leads to vortex pairing once the development leaves the linear stage. The study also provides evidence of a relationship between the turbulence intensity and the length of the near wake. The relationship, however, needs to be calibrated against measurements. Copyright © 2010 John Wiley & Sons, Ltd.
Transportable EDXRF analysis of environmental water samples using Amberlite IRC748 ion‐exchange preconcentration
Authors: Heiden E. S. , Gore D. B. , Stark S. C.
Published: March 2010

Transportable energy‐dispersive X‐ray fluorescence spectrometers allow on‐site assessment of metal‐contaminated soils, sediments and other solids. Multi‐element analysis of liquid samples, such as surface water, groundwater, acid leach and aqueous soil extracts, would enhance on‐site environmental assessments. However, transportable spectrometers typically have detection limits for metals in waters of approximately 1–10 mg l−1, whereas many toxic elements are regulated at concentrations of 1–100 µg l−1. If detection limits for this technique can be lowered, then only one analytical tool, a transportable XRF spectrometer, may be sufficient for remote areas, increasing program flexibility and reducing the amount of equipment that needs to be purchased, transported and operated. This research develops an in‐field preconcentration technique using Amberlite IRC748 cation‐exchange resin, followed by XRF analysis of Fe, Ni, Cu, Zn and Pb at µg l−1 concentrations in aqueous samples. The operational parameters tested to maximise analyte recovery included flow rate, and the mass and chemical form of the resin. The method was tested with extracts from landfill soils and surface waters from a derelict base metal mine. The method recovered Cu, Zn and Pb accurately, and Ni and Fe at concentrations satisfactory for screening purposes. Copyright © 2010 John Wiley & Sons, Ltd.
Comparison of three portable EDXRF spectrometers for pigment characterization
Authors: Bonizzoni Letizia , Caglio Simone , Galli Anna , Poldi Gianluca
Published: March 2010

In the field of cultural heritage analyses, energy dispersive X‐ray fluorescence is a well known nondestructive technique used—among other applications—to characterize pigments and inks in artifacts such as paintings, polychromous sculptures and illuminated manuscripts. In this paper, we report on the performance of three portable X‐ray fluorescence analyzers currently used for laboratory or in situ analyses. The three spectrometers have been tested in laboratory on paint layers prepared to simulate real ones, with the specific goal to determine advantages and disadvantages for each instrument in the detection of specific elements characterizing the pigment. Additionally, overall general advantages and limitations of each system in practical use are highlighted. Copyright © 2010 John Wiley & Sons, Ltd.