bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: Functional Supramolecular Systems with Highly Cooperative and Responding Properties
Authors: Nabeshima Tatsuya , Akine Shigehisa
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Aminophosphines: Their Chemistry and Role as Ligands and Synthons
Authors: Gopalakrishnan Janarthanan
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Hydrogenation of CO2‐Expanded Liquid Terpenes: Phase Equilibrium Controlled Kinetics
Authors: Bogel‐Lukasik Ewa , Serbanovic Ana , Bogel‐Lukasik Rafal , Banet‐Osuna Anna , Najdanovic‐Visak Vesna , Nunes da Ponte Manuel
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Noncovalently Anchored Catalysts Based on Chiral P‐Ligands
Authors: Masters Antony F. , Ward Antony J. , Maschmeyer Thomas
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Tropos Phosphorus Ligands and Corresponding Chiral Metal Catalysts
Authors: Otero Iran , Boerner Armin
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Atropisomeric Partially Hydrogenated 1,1′‐Binaphthyl Diphosphines
Authors: Li Yue‐Ming , Yan Ming , Chan Albert S. C.
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Catalysts with Chiral Self‐Assembling P‐Ligands
Authors: Seiche Wolfgang , Breit Bernhard
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Chiral Diazaphospholidine Ligands
Authors: Buono Gerard , Toselli Nicolas , Martin David
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: New Synthetic Strategies for Medium‐Sized and Macrocyclic Compounds by Palladium‐Catalyzed Cyclization
Authors: Majumdar K. C. , Chattopadhyay Buddhadeb
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Eight‐Membered and Larger Rings
Authors: Newkome George R.
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Six‐Membered Ring Systems — Pyridine and Benzo Derivatives
Authors: Hopper Darrin W. , Kutterer Kristina M. K. , Crombie Aimee L. , Clemens Jeremy J.
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Five‐Membered Ring Systems with O and S (Se, Te) Atoms
Authors: Aitken R. Alan , Power Lynn A.
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Five‐Membered Ring Systems with More than One N Atom
Authors: Yet Larry
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Syntheses and Transformations of 2‐Methyleneaziridines and 2‐Methyleneazetidines
Authors: Tehrani Kourosch Abbaspour , De Kimpe Norbert
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Five‐Membered Ring Systems: Thiophenes and Se (Te) Analogues
Authors: Janosik Tomasz , Bergman Jan
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Bioinformatic Perspectives on NRPS/PKS Megasynthases: Advances and Challenges
Authors: Jenke‐Kodama Holger , Dittmann Elke
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Blue Flower Color Development by Anthocyanins: From Chemical Structure to Cell Physiology
Authors: Yoshida Kumi , Mori Mihoko , Kondo Tadao
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Chemistry and Biology of Nontetramic γ‐Hydroxy‐γ‐lactams and γ‐Alkylidene‐γ‐lactams from Natural Sources
Authors: Nay Bastien , Riache Nassima , Evanno Laurent
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Biosolids Composting
Authors: Shammas Nazih K. , Wang Lawrence K.
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Quantum Monte Carlo for Atoms, Molecules and Solids
Authors: Lester William A. , Mitas Lubos , Hammond Brian
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Structural Insights into Nonribosomal Peptide Enzymatic Assembly Lines
Authors: Koglin Alexander , Walsh Christopher T.
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Layer‐by‐Layer Liquid‐Phase Epitaxy of Crystalline Coordination Polymers at Surfaces
Authors: Fischer Roland A. , Woell Christof
Published: October 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Insulin – Protein mit langer Geschichte. Der Schlüssel zur Diabetes‐Therapie
Authors: Meichsner Beate , Wirth Uwe
Published: October 2009

Das Hormon Insulin ist seit langem sowohl von wissenschaftlichem als auch von industriellem Interesse. So stand es zweimal im direkten Zusammenhang mit dem Nobelpreis. 1923 wurden Frederick Banting und John James Richard Macleod für die Entdeckung des Insulins mit dem Nobelpreis für Medizin geehrt und 1958 erhielt Frederik Sanger den Nobelpreis für Chemie für die Strukturaufklärung des Hormons. Insulin war das erste Protein, dessen chemische und räumliche Struktur aufgeklärt werden konnte und es war das erste mit Hilfe von gentechnisch modifizierten Mikroorganismen hergestellte Arzneimittel. Das aufwändige biotechnologische Verfahren macht seit den 1980er Jahren die Insulinherstellung unabhängig von tierischen Pankreaten, die für die weltweit wachsende Zahl an Diabetikern nicht in ausreichendem Umfang zur Verfügung gestanden hätten.
Unverzichtbar gegen Bakterien: Antibiotika. 80 Jahre Verwendung von Antibiotika in der Medizin
Authors: Meinert Sabine , John Ernst
Published: October 2009

Auch 80 Jahre nach der Entdeckung von Penicillin ist die Forschung nach neuen Antibiotika noch nicht abgeschlossen. Zunehmendes Auftreten von Resistenzen gegenüber den verwendeten Antibiotika erfordern einen verantwortungsvollen Einsatz bekannter Anibiotika und die Entwicklung verbesserter Medikamente. Mittlerweile existieren 8000 antibiotisch wirksame Substanzen, von denen ca. 100 in der Medizin angewandt werden. Trotzdem gibt es zahlreiche Infektionen, die nicht ausreichend behandelt werden können.

Antibiotika werden in der Human‐ und Veterinärmedizin eingesetzt. Der bedenkliche Einsatz als Ergotropika, um die Infektionsraten von Masttieren zu vermindern und die Futterverwertung der Tiere zu steigern, konnte in den letzten Jahren zurückgedrängt werden.

Die teils unsachgemäße Anwendung erzeugt einen selektiven Druck, der Resistenzen bei den Erregern hervorruft. Ihr bedrohlicher Einfluss auf die Therapie vor allem gramnegativer Bakterien könnten manche Teile der Welt in eine präantibiotische Ära zurückversetzen, da sich adäquate Therapiemöglichkeiten zunehmend verringern. Dies unterstreicht wiederum die Wichtigkeit neue Antibiotika bzw. neue Therapieansätze zu entwickeln. Ideen dazu gibt es genug.
Kegelschnecken als Fundgrube neuer Wirkstoffe. Medizin aus dem Meer
Authors: Terlau Heinrich
Published: October 2009

Ein wichtiger Schritt bei der Entwicklung neuer Medikamente ist die Identifizierung von Substanzen mit neuen, krankheitsrelevanten Wirkmechanismen. Diese Substanzen können dann als Leitstrukturen Ausgangspunkt für die Weiterentwicklung dieser Substanzgruppe zum eigentlichen Medikament sein. Eine der Strategien, neue Substanzen mit bisher unbekannten Wirkmechanismen zu finden, ist, in der Natur nach biologisch aktiven Verbindungen zu suchen und den Mechanismus dieser Wirkungen zu untersuchen. Ein Beispiel für dieses “Lernen aus der Natur” ist die Analyse der Wirkungsweise der Gifte von den räuberisch im Meer lebenden Kegelschnecken.

Die Gifte der Kegelschnecken bestehen aus einer außerordentlichen Vielzahl von Peptiden, den Conopeptiden, von denen die einzelnen Peptide als absolute Spezialisten hochspezifisch mit verschiedenen Ionenkanälen und Rezeptoren interagieren. Ionenkanäle und Rezeptoren sind membrangebundene Proteine, die praktisch in allen Zellen vorkommen und an den verschiedensten physiologischen Prozessen beteiligt sind. Aufgrund ihrer Bedeutung für die elektrische Erregbarkeit von Zellen sind Ionenkanäle häufig Zielmoleküle von Giften. Verschiedene Conopeptide befinden sich bereits in der klinischen Erprobung und das analgetisch wirkende Peptid ω‐Conotoxin MVIIA (Ziconotide; Prialt®) ist eines der ersten zugelassenen Medikamente aus einem marinen Naturstoff.
Neues vom Malaria‐Erreger
Authors: Harrer Roswitha
Published: October 2009

Die jüngst in Kambodscha entdeckte Resistenz des Malaria‐Erregers Plasmodium falciparum gegen Artemisinin‐Derivate lässt Mediziner Alarm schlagen. Zu Artemisinin gibt es nämlich keine Alternative.
Adiabatic shock capturing in perfect gas hypersonic flows
Authors: Kirk Benjamin S.
Published: October 2009

This paper considers the streamline‐upwind Petrov/Galerkin (SUPG) method applied to the compressible Euler and Navier–Stokes equations in conservation‐variable form. The spatial discretization, including a modified approach for interpolating the inviscid flux terms in the SUPG finite element formulation, is briefly reviewed. Of particular interest is the behavior of the shock‐capturing operator, which is required to regularize the scheme in the presence of strong, shock‐induced gradients. A standard shock‐capturing operator that has been widely used in previous studies by several authors is presented and discussed. Specific modifications are then made to this standard operator that is designed to produce a more physically consistent discretization in the presence of strong shock waves. The actual implementation of the term in a finite‐dimensional approximation is also discussed. The behavior of the standard and modified scheme is then compared for several supersonic/hypersonic flows. The modified shock‐capturing operator is found to preserve enthalpy in the inviscid portion of the flowfield substantially better than the standard operator. Published in 2009 by John Wiley & Sons, Ltd.
Saffron yellow: characterization of carotenoids by high performance liquid chromatography with electrospray mass spectrometric detection
Authors: Lech Katarzyna , Witowska‐Jarosz Janina , Jarosz Maciej
Published: October 2009

Saffron is one of the oldest natural dyestuffs and is obtained from the dried stigmata of Crocus sativus L. Nowadays, saffron is considered as an invaluable spice of golden‐yellow hue, a precious ingredient in the Eastern and Mediterranean cuisines. It is characterized by a bitter taste that is caused by the chemical properties of its constituents. The yellowness of saffron results from the presence of crocins (glycosyl esters of crocetin), its main color compounds, which are examined in the present study in the crude methanol extracts by high performance liquid chromatography (HPLC) coupled with spectrophotometric and electrospray mass spectrometric detection (HPLC–UV‐Vis–ESI MS). This technique allowed the separation and identification of trans‐ and cis‐isomers of crocins. Their mass spectra registered in the negative ion mode comprised the quasi‐molecular and fragment ions, as well as a range of other ions. Doubly charged ions were found for trans‐isomers only, due to the high symmetry of their molecules. Modification of the eluent allowed the identification of several signals corresponding to adduct ions of crocins with the used additives. Copyright © 2009 John Wiley & Sons, Ltd.
Chemical and nutritional quality of silage made from raw or cooked lizard fish (Saurida undosquamis) and blue crab (Portunus pelagicus)
Authors: Mach Diep TN , Nortvedt Ragnar
Published: October 2009

Twelve silages were prepared from uncooked or cooked lizard fish (Saurida undosquamis) and blue crab (Portunus pelagicus) and stored at ambient temperature (30 ± 2 °C) for 60 days. The antioxidative effect of adding ethoxyquin was also investigated. Generally, the nutritional quality of all the silages was stable for up to 60 days of storage and the composition of raw materials was reflected in the composition of the silages. Crab had a lower level of crude protein than fish (85 versus 162 mg kg−1), but a higher level of ash (96 versus 36 g kg−1); moreover, there were significant differences in nutritional composition between uncooked and cooked materials. High level of ash in crab required addition of high levels of formic acid in crab‐related silages. At the end of the experiment cooked silages showed a tendency for spoilage; in particular, maggots were observed in cooked crab silages on the last few days of the experiment. Comparison of treatments with or without ethoxyquin showed that only rancidity of fish silage groups was higher without addition of ethoxyquin. Uncooked materials are more suitable for prolonged storage than cooked materials, and it is probably not necessary to add antioxidants to silages made from material with low lipid content. Copyright © 2009 Society of Chemical Industry
Scaling of transient wave–soil interaction problems
Authors: Xiao Heng , Young Yin Lu , Prévost Jean H.
Published: October 2009

Within the framework of compressible multi‐phase flow through deformable porous media, wave–soil interactions in the near‐shore region during wave runup and drawdown are modeled. Critical non‐dimensional parameters governing the interaction processes are identified. Within the context of wave basin and centrifuge wave tank facilities, we propose scaling relations for the experimental investigations of the transient and steady‐state responses of wave–soil systems. Numerical simulations are conducted to illustrate and confirm the theoretical and scaling analyses. Based on the simulations results, the implications on the design of experiments and interpretation of results are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Sensitivity analyses of FORM‐based and DRM‐based performance measure approach (PMA) for reliability‐based design optimization (RBDO)
Authors: Lee Ikjin , Choi K. K. , Gorsich David
Published: October 2009

In gradient‐based design optimization, the sensitivities of the constraint with respect to the design variables are required. In reliability‐based design optimization (RBDO), the probabilistic constraint is evaluated at the most probable point (MPP), and thus the sensitivities of the probabilistic constraints at MPP are required. This paper presents the rigorous analytic derivation of the sensitivities of the probabilistic constraint at MPP for both first‐order reliability method (FORM)‐based performance measure approach (PMA) and dimension reduction method (DRM)‐based PMA. Numerical examples are used to demonstrate that the analytic sensitivities agree very well with the sensitivities obtained from the finite difference method (FDM). However, as the sensitivity calculation at the true DRM‐based MPP requires the second‐order derivatives and additional MPP search, the sensitivity derivation at the approximated DRM‐based MPP, which does not require the second‐order derivatives and additional MPP search to find the DRM‐based MPP, is proposed in this paper. A convergence study illustrates that the sensitivity at the approximated DRM‐based MPP converges to the sensitivity at the true DRM‐based MPP as the design approaches the optimum design. Hence, the sensitivity at the approximated DRM‐based MPP is proposed to be used for the DRM‐based RBDO to enhance the efficiency of the optimization. Copyright © 2009 John Wiley & Sons, Ltd.
Non‐linear dynamic analyses by meshless local Petrov–Galerkin formulations
Authors: Soares D. , Sladek J. , Sladek V.
Published: October 2009

In this work, meshless methods based on the local Petrov–Galerkin approach are proposed for the solution of dynamic problems considering elastic and elastoplastic materials. Formulations adopting the Heaviside step function and the Gaussian weight function as the test functions in the local weak form are considered. The moving least‐square method is used for the approximation of physical quantities in the local integral equations. After spatial discretization is carried out, a non‐linear system of ordinary differential equations of second order is obtained. This system is solved by Newmark/Newton–Raphson techniques. At the end of the paper numerical results are presented, illustrating the potentialities of the proposed methodologies. Copyright © 2009 John Wiley & Sons, Ltd.
One‐step separation and purification of rupestonic acid and chrysosptertin B from Artemisia rupestris L. by high‐speed counter‐current chromatography
Authors: Yang Yi , Gu Dongyu , Yili Abulimiti , Zhao Yongxin , He Dajun , Aisa Haji Akber
Published: October 2009

Introduction – Artemisia rupestris L. is a well‐known traditional Chinese medicinal plant in Xinjiang. Rupestonic acid is the main active ingredient of A. rupestris L., and has been chosen as a ‘marker compound’ for the chemical evaluation or quality control of A. rupestris L. and its products. Although HSCCC separation method was developed before, the separation was performed with two steps using the same solvent system, which were time‐consuming and waste of the solvents.

Objective – To develop a simple HSCCC method for the separation and purification of rupestonic acid in a single run.

Methodology – The measurement of partition coefficient (K) was introduced to select the two‐phase solvent system. The simple HSCCC method was established according to the selected solvent system for separation and purification of rupestonic acid. The purity of target compound was test by HPLC and the structure was identified by MS, 1H NMR and 13C NMR.

Results – A total of 72.3 mg of rupestonic acid and 53.5 mg of chrysosptertin B with over 95% purity were yielded from 500 mg extracts of Artemisia rupestris L. in one‐step separation.

Conclusion – The rupestonic acid was separated in a single run by HSCCC. Copyright © 2009 John Wiley & Sons, Ltd.
Optoelectronic performance of poly(p‐phenylenevinylene)‐based heterostructures evaluated by scanning probe techniques
Authors: Čermák Jan , Rezek Bohuslav , Cimrová Věra , Výprachtický Drahomír , Hörhold Hans‐Heinrich , Ledinský Martin , Fejfar Antonín
Published: October 2009

Thin polymer blend films made of donor and acceptor poly(p‐phenylenevinylene) (PPV)‐based polymers were prepared. Diverse scanning probe techniques (atomic force microscopy (AFM), Kelvin force microscopy (KFM), current‐sensing AFM (CS‐AFM), and micro‐Raman mapping) are used to characterize morphologic, electronic as well as optoelectronic properties of the heterostructures. Morphologies of the heterostructures are correlated with microscopic and macroscopic electronic response to a broad‐band visible illumination. The data are discussed with respect to photovoltaic applications.
Temperature modification of oxidized multiwall carbon nanotubes studied by electron spectroscopy methods
Authors: Lesiak Beata , Zemek Josef , Jiricek Petr , Stobinski Leszek
Published: October 2009

Carbon nanotubes (CNTs) offer interesting applications in nanotechnology, biochemistry, biomedicine, catalysis, electronics, optoelectronics, electrochemistry, and sensor technologies. They could also be used as a filler for metallic nanoparticle composites prepared at elevated temperatures by sintering. In the present work the oxidized multiwall carbon nanotubes (ox‐MWCNTs) are investigated. The aim is their characterization after oxidation reaction, investigation of their temperature stability and the influence of temperature modification on the structural and chemical changes in the atomic bonding state during annealing. The ox‐MWCNTs are studied in the temperature range from RT (25 °C) to 150 °C by X‐ray photoelectron spectroscopy (XPS), X‐ray induced Auger electron spectroscopy (XAES), elastic peak electron spectroscopy (EPES), quadrupole mass spectroscopy (QMS), transmission electron microscopy (TEM), Fourier transform infra‐red spectroscopy (FTIR) methods. The FTIR and XPS results indicate the presence of water, carboxyl, hydroxyl, carbonyl, ester, and acid anhydride groups in the bulk and at the surface. Annealing decreases the oxygen content (from 12.4 to 9.8 at.%), accompanied by increasing amount of C sp2 groups (from 63 to 74%), indicating the reconstruction of C bonds. For the applied temperature range increasing content of water is observed, whereas decreasing content of other carbon–oxygen groups, i.e., carbonyl, carboxyl, hydroxyl, ester, and acid anhydride. This decrease undergoes with different rate. The QMS at 150 °C showing the largest contribution of CO2, indicates major desorption of oxygen groups from the edges of ox‐MWCNTs, whereas desorption of oxygen from the bridges visible as CO is minor. The surface structural changes in EPES spectra at the temperature of 150 °C confirm increasing surface imperfection. The proposed method of chemical oxidation also results in significant elimination of amorphous carbon and metallic residues from as prepared MWCNTs.

magnified image

The TEM image of ox‐MWCNTs.
Investigations of N@C60 and N@C70 stability under high pressure and high temperature conditions
Authors: Iwasiewicz‐Wabnig Agnieszka , Porfyrakis Kyriakos , Briggs G. Andrew D. , Sundqvist Bertil
Published: October 2009

Endohedral fullerenes encapsulating single nitrogen atoms (N@C60 and N@C70) are spin active, due to the presence of unpaired nitrogen electron spins. High reactivity of nitrogen leads to a poor stability of these molecules at elevated temperatures, drastically restricting possibilities of their chemical treatment. In this study, N@C60 and N@C70 in toluene solutions were subjected to high pressure (HP) up to 0.8 GPa and annealed for 1, 2, 10 or 24 h, at either room or elevated temperatures. In each case the number of surviving molecules was evaluated based on the relative spin counts of ex situ EPR spectra obtained before and after the treatment. The enhanced thermal stability of N@C60 and N@C70 under HP conditions is attributed to inhibited formation of azabridges, which under normal pressure facilitate the escape of nitrogen from the fullerene cage.
Spectroscopy of single‐walled carbon nanotubes in aqueous surfactant dispersion
Authors: Movia Dania , Del Canto Elisa , Giordani Silvia
Published: October 2009

Optical studies of single‐walled carbon nanotubes (SWNTs) dispersed in aqueous surfactant suspensions have made significant progress since the discovery of their bright band‐gap fluorescence in the near‐infrared region [M. J. O'Connell et al., Science 297, 593–596 (2002)]. In this article we report the systematic investigation of the effect of chemical purification and oxidation on the spectroscopic properties of SWNTs. The SWNTs samples we prepared differ for the percentage of impurities present, the amount of defects introduced in their graphitic structure and/or the functional groups expressed on their surface. The generation of carboxylic groups on the nanotubes surface by oxidative treatment was validated by means of thermal gravimetric analysis and ATR/Fourier transform IR spectroscopies, as well as Raman spectroscopy. We have solubilized pristine, purified SWNTs (p‐SWNTs) and oxidized SWNTs (o‐SWNTS) in Milli‐Q water using sodium dodecylbenzene sulphonate (SDBS). While our Vis‐NIR Absorption spectra of p‐SWNTs and o‐SWNTS dispersions in aqueous SDBS solution show the loss of the resolution of the characteristic van Hove singularities, NIR Photoluminescence spectra are characterized by structured emission peaks.
Characterization of dye molecules and carbon nanostructures by tip‐enhanced Raman spectroscopy
Authors: Peica Niculina , Röhrig Serge , Rüdiger Andreas , Brose Katharina , Thomsen Christian , Maultzsch Janina
Published: October 2009

Tip‐enhanced Raman spectroscopy (TERS) is a high sensitivity and high spatial resolution analytical technique based on the strong field enhancement provided by a sharp metallic tip. Using a commercial atomic force microscope (AFM) combined with a confocal optical setup in reflection geometry, we are targeting samples on non‐transparent electrodes. The resulting design challenges with respect to quantum efficiency, optical accessibility of the tip and the optics themselves, were balanced and taken into consideration for the presented ultra‐high vacuum–TERS setup. Second, we describe the development of a TERS setup at normal pressure in air, and we present the confocal Raman and TERS spectra of dye molecules and other nanostructures.
Development of graphene layers by reduction of graphite fluoride C2F surface
Authors: Okotrub A. V. , Asanov I. P. , Yudanov N. F. , Babin K. S , Gusel'nikov A. V. , Nedoseikina T. I. , Gevko P. N. , Bulusheva L. G. , Osváth Z. , Biró L. P.
Published: October 2009

We studied a possibility of reduction of the surface of graphite fluoride obtained by fluorination of highly oriented pyrolytic graphite (HOPG) by a gaseous mixture of BrF3 and Br2. X‐ray diffraction (XRD) revealed a layered structure of the fluorinated product being a second‐stage intercalate due to a presence of bromine molecules between the fluorinated graphite layers. Scanning tunneling microscopy and spectroscopy showed that the “old” surface of graphite fluoride (exposed to the ambient air) has the graphite‐like structure, while the fresh cleaved surface is non‐conductive. Therefore, the outer layers of graphite fluoride can be reduced by water present in the laboratory atmosphere. The sample was treated by H2O vapor to confirm that. The reduction was controlled by Raman spectroscopy using intensity of the 1360 and 1580 cm−1 bands. The energy dependent photoelectron spectroscopy was used for estimation of thickness of the reduction layer, which was found, does not exceed 2–3 graphite layers. The obtained results indicate the possibility of synthesis of graphene layers on dielectric fluorinated graphite matrix.
Microstructural study of He‐implanted Fe‐Cr alloys with the use of conventional lifetime technique and pulsed low energy positron beam
Authors: Kršjak Vladimír , Slugen Vladimír , Petriska Martin , Sojak Stanislav , Egger Werner
Published: October 2009

Experimental simulation of the radiation damage using He+ implantation has been performed in research of Fe‐Cr model alloys. Different chromium content in the studied materials enables investigations of the effect of this element on the microstructure of radiation treated materials. The damaged region was investigated with the positron lifetime techniques with focus on the size and distribution of the defects. Our measurements show that not only pulsed low energy positron beam spectroscopy (PLEPS) but also conventional lifetime spectroscopy can study the behaviour of vacancy type defects induced by implantation of charged particles. Our results show that initial microstructure of low Cr alloys with significant presence of vacancy type defects is less resistant to creation of defect agglomeration in comparison with higher Cr alloys. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructural study of high irradiated reactor steels
Authors: Slugen Vladimír , Kršjak Vladimír , Petriska Martin , Sojak Stanislav , Veterníková Jana
Published: October 2009

Positron Annihilation Spectroscopy (PAS) techniques in combination with other techniques were effectively used in the testing and selection process of optimal reactor steels for use in Generation III and IV reactors or thermonuclear fusion facilities. Conventional PAS lifetime technique and pulsed low energy positron system were applied on wide spectrum of reactor steels together with other techniques viz., Transmis sion Electron Microscopy and Mossbauer Spectroscopy focused on the role of Nickel in the steel microstructure. Experimental experiences in this area collected over the last twenty years were very useful in the actual study by avoiding many mistakes in handling with specimens or in careful interpretation of the results. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A mini linac based positron source
Authors: Pérez Patrice , Liszkay Laszlo , Rey Jean‐Michel , Blideanu Valentin , Carty Mickael , Curtoni Aline , Delferrierre Olivier , Dupré Pierre , Muranaka Tomoko , Ruiz Nicolas , Sacquin Yves
Published: October 2009

We have installed in Saclay a demonstration setup for an intense positron source in November 2008. It is based on a compact 6 MeV electron linac to produce positrons via pair production on a tungsten target. A relatively high current of 0.15 mA compensates the low energy, which is below the neutron activation threshold. The expected production rate is 4x1011 fast positrons per second. A set of coils is arranged to select the fast positrons from the diffracted electron beam in order to study the possibility to use a rare gas cryogenic moderator away from the main flux of particles. A first part of the commissioning of the linac has been performed. First attempts at measuring the fast positron flux are underway. This setup is part of a project to demonstrate the feasibility of an experiment to produce the H+ ion for a free fall measurement of neutral antihydrogen (H). Its small size and cost could be of interest for a university laboratory or industry for materials science applications. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recent development of the PAES set up at NEPOMUC
Authors: Mayer J. , Schreckenbach K. , Hugenschmidt C.
Published: October 2009

Positron annihilation induced Auger electron spectroscopy (PAES) enables background free, non destructive surface analysis. Until now the long measurement time of up to several days restricted the area of application. In this paper the new set up at the reactor based positron source NEPOMUC is presented as well as first measurements with a new, efficient electron energy analyzer. For the first time, overview Auger spectra are now available in less than 15 minutes. Furthermore the high energy resolution of the PAES system is presented with the resolution of the copper M2,3VV double peak using PAES (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mn doping in ZnO nanoparticles: effects investigated by positron lifetime and Doppler broadening studies
Authors: Roy B. , Karmakar B. , Pal M. , Nambissan P. M. G.
Published: October 2009

Positron lifetime and Doppler broadening measurements in nanocrystalline zinc oxide (ZnO) indicated the negatively charged trivacancy‐type defects VZn+O+Zn as the predominant positron trapping sites within the nanocrystallites. They got converted to neutral divacancies (VZn+O) on doping with manganese (Mn). Further doping resulted in the reduction of the size of the nanocrystallites. At still increased doping concentrations, a new phase ZnMn2O4 was formed. It had a normal spinel structure with positron trapping centers at some of the tetrahedral and octahedral sites. X‐ray diffraction and transmission electron micro‐scopy studies confirmed these findings. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Migration behavior of vacancies in electron irradiated Fe‐Cu alloys
Authors: Cao Xingzhong , Xu Qiu , Sato Koichi , Yoshiie Toshimasa
Published: October 2009

The formation of Cu precipitates in Cu containing steels is one of the key factors leading to embrittlement in reactor pressure vessel steels. Cu precipitates are formed by the migration of vacancies in steels and the behaviour of these vacancies is therefore important. In the present study, vacancies were introduced into Fe‐Cu alloys by electron irradiation with 28 MeV at 100 K. The effects of Cu concentration and tiny Cu precipitates on the migration of vacancies and growth of precipitates in Fe‐Cu alloys were investigated by positron annihilation lifetime measurements. The effect of Cu concentration between Fe‐0.3 mass% Cu to Fe‐0.6 mass% Cu on the migration of vacancies and the formation of Cu precipitates was negligible small. The formation of Cu precipitates was found to decrease the migration temperature of vacancies. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron annihilation studies of NiO nanoparticles prepared through two different chemical routes
Authors: Das Soumen , Ghoshal Tandra , Nambissan P. M. G.
Published: October 2009

Nanocrystalline samples of nickel oxide were synthesized through solvothermal and sol‐gel routes, and the grain sizes were determined through x‐ray diffraction and transmission electron microscopy. Fourier transform infrared, optical absorption and positron annihilation spectroscopy studies were done to characterize them further and study the defects at nanoscale. The onset of quantum confinement effects is indicated by characteristic blue‐shift in optical absorption spectra and widening of the band gap. Positron annihilation parameters changed as a result and the causes are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vorticity, deformation and divergence signals associated with stratosphere–troposphere exchange
Authors: Jaeger E. B. , Sprenger M.
Published: October 2009

The dynamical tropopause of the extratropics, defined as an isosurface of potential vorticity, acts as a barrier to stratosphere–troposphere exchange (STE). Therefore, any transport across this barrier is necessarily associated with diabatic or frictional processes such as turbulence, radiative forcing or condensational heating. Most of these processes are linked to distinct flow phenomena and hence with distinct signatures of the velocity field. The focus of this study is on the characteristics of the velocity field at the time and location of the tropopause crossing, as given by the flow‐components divergence (DIV), deformation (DEF) and vorticity (VORT). Firstly, the prevalence of distinct signals is shown for three case studies. Then a Lagrangian climatology of STE is used to assess the climatological aspects of this link for the year 1990. Methodologically, the flow‐field components are traced along the STE trajectories, both derived from ERA‐40. Some key results of this study are as follows. (1) DEF, positive values of VORT and negative values of DIV are markedly correlated with stratosphere‐to‐troposphere transport (STT). Therefore, the typical flow field associated with STT is deformative, cyclonic and convergent. (2) For troposphere‐to‐stratosphere transport (TST), the link with the flow‐field components is less pronounced. DEF, VORT and DIV all show small, but distinct local maxima just before the exchange. The flow field during TST is therefore rather divergent and less cyclonic. (3) Sensitivity studies reveal that these findings are robust with respect to temporal and spatial variability. Copyright © 2009 Royal Meteorological Society
A context‐aware handover decision based on user perceived quality of service trigger
Authors: Ghahfarokhi Behrouz Shahgholi , Movahhedinia Naser
Published: October 2009

Growing demands for pervasive and ubiquitous services over wireless mobile networks and evolution of such networks towards heterogeneous solutions have emphasized the necessity of more intelligent handoff decisions. The existing handoff management methods in the literature are mostly using signal strength measurements and other link quality evaluations not addressing the knowledge about context of mobile devices, users and networks. Recently, context‐aware handoff management has been considered as a novel candidate for fourth generation (4G) wireless technology. In this paper, user perceived quality of service has been considered in addition to traditional contexts such as user preferences, application requirements, network parameters and link quality for decision making. User perceived quality (UPQ) has been employed as a trigger source, in addition to link layer triggers which are emerged using media independent handover (MIH) event service. This paper presents a policy based mechanism for handoff decision making where fuzzy petri nets (FPNs) have been utilized as its evaluation algorithm. A case study has been provided by simulations to show the usability and user level satisfaction. Simulation results show superior performance in terms of UPQ, jitter and packet delivery measures. Copyright © 2009 John Wiley & Sons, Ltd.
Efficient ARQ protocols with anti‐jamming coding for cognitive radios
Authors: Yue Guosen , Wang Xiaodong
Published: October 2009

We introduce simple yet efficient automatic retransmission request (ARQ) protocols in conjunction with two types of anti‐jamming coding techniques—rateless coding and piecewise coding—for protecting secondary users' data transmissions in cognitive radio systems. For piecewise coding, we propose to employ systematic codes to facilitate efficient selected retransmissions and design short codes to maximize secondary user throughput. For rateless coding, we consider a protocol that transmits new parity packets during retransmission and show that this scheme is stable if the jamming rate of the system is within a certain range. It is seen that for both anti‐jamming coding schemes, the corresponding simple ARQ protocols provide significant improvement in secondary user throughput. Moreover, the piecewise coding together with its ARQ protocol offers similar or better throughput performance compared with the rateless coding counterpart, without incurring the stability issue. Copyright © 2009 John Wiley & Sons, Ltd.
Unroofing and Curettage for the Treatment of Acute and Chronic Pilonidal Disease
Authors: Kepenekci Ilknur , Demirkan Arda , Celasin Haydar , Gecim Ibrahim Ethem
Published: October 2009

Background

Various surgical techniques are available in the management of pilonidal sinus, but controversy concerning the optimal surgical approach persists. The present study analyzes the outcome of unroofing and curettage as the primary intervention for acute and chronic pilonidal disease.

Methods

A total of 297 consecutive patients presenting with chronic disease, acute abscess, or recurrent disease were treated with unroofing and curettage. The wound was left open to heal by secondary intention. Hospitalization, time required to resume daily activities and return to work, healing time, and recurrence rates were recorded.

Results

All patients were discharged within the first 24 h after operation. The median period before returning to work was 3.2 ± 1.2 days, and the mean time for wound healing was 5.4 ± 1.1 weeks. Six patients were readmitted with recurrence of the disease within the first six postoperative months. All recurrences were in patients who did not follow the wound care advice and who did not come to regular weekly appointments. Patients with recurrence underwent repeat surgery by the same technique with good results.

Conclusions

Unroofing and curettage for pilonidal sinus disease is an easy and effective technique. The vast majority of the patients, including those with abscess as well as those with chronic disease, will heal with this simple procedure, after which even recurrences can be managed successfully with the same procedure. Relying on these results, we advocate unroofing and curettage as the procedure of choice in the management of pilonidal disease.
“Blitz Surgery”: Redefining Surgical Needs, Training, and Practice in Sub‐Saharan Africa
Authors: Nthumba Peter M.
Published: October 2009

Background

Most reconstructive surgery in Sub‐Saharan Africa is provided by numerous noncoordinated individuals and organizations, in multiple short trips, or “surgical blitzes.” Because many such groups do not train local surgeons, these communities have become dependent on unsustainable systems. By providing much‐needed care to otherwise neglected areas, the blitzes offer an easy solution to what would otherwise be the source of a significant headache to local governments.

Methods

The collection of data and other material in this highly ambiguous and fluid field is nearly impossible, as scientific papers on the results of poor surgical treatment, especially in the realm of humanitarian medicine, do not exist: The author has had to rely on personal experience and community interaction to reach the views and conclusions articulated in this article.

Results

Although not the rule, blitz surgeries have poorer outcomes than in‐hospital procedures, primarily because of inadequate preoperative and postoperative care.

Conclusions

Although the value of blitz surgery in meeting some of the surgical needs of otherwise neglected communities is undeniable, the author seeks to provoke a sober reexamination of these efforts vis‐à‐vis the long‐term sustainability of such programs, with the objective of harnessing strengths that would see the evolution of a new reconstructive surgical service tailor‐made for Africa—affordable and sustainable yet able to deliver quality surgical care to the remotest villages. Otherwise, these humanitarian efforts’ will continue to be ‘drops in the ocean, meeting the needs of a few in the community but resulting in no long‐term gains.
Facile Fabrication of Ultrafine Hollow Silica and Magnetic Hollow Silica Nanoparticles by a Dual-Templating Approach
Authors: Wu Wei , Xiao Xiangheng , Zhang Shaofeng , Fan Lixia , Peng Tangchao , Ren Feng , Jiang Changzhong
Published: October 2009

The development of synthetic process for hollow silica materials is an issue of considerable topical interest. While a number of chemical routes are available and are extensively used, the diameter of hollow silica often large than 50 nm. Here, we report on a facial route to synthesis ultrafine hollow silica nanoparticles (the diameter of ca. 24 nm) with high surface area by using cetyltrimethylammmonium bromide (CTAB) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as co-templates and subsequent annealing treatment. When the hollow magnetite nanoparticles were introduced into the reaction, the ultrafine magnetic hollow silica nanoparticles with the diameter of ca. 32 nm were obtained correspondingly. Transmission electron microscopy studies confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow.