bluuebunny/crossref_metadata_2025 huggingface dataset:
Some examples for the selection of tunnelling methods / Wahl der Vortriebsmethode anhand von Beispielen
Authors: Spiegl Markus , Schneider Eckart
Published: October 2011

Today it is necessary to systematically consider the selection of the tunnelling method at a very early stage of a project. These early considerations regarding the construction method are usually necessary because of the approval (e.g. EIA) or award regulations, or are essential for the evaluation of tenders. The quite different procedures that can be applied on individual projects are illustrated through three examples.

Bereits in sehr frühen Projektphasen ist es heute notwendig, systematische Überlegungen zur Wahl der Vortriebsmethode anzustellen. Diese frühe Festlegung auf die Vortriebsmethode resultiert meist aus genehmigungsrechtlichen (z.B. UVP) oder vergaberechtlichen Gründen bzw. Angebotsbewertungszwängen. Mit welchen unterschiedlichen Herangehensweisen die projektspezifisch oft vollkommen unterschiedlichen Randbedingungen erfüllt werden können, wird exemplarisch an drei Beispielen gezeigt.
Granitztal tunnel chain – tunnelling method decision‐making process / Tunnelkette Granitztal – Entscheidungsfindung der Vortriebsmethode
Authors: Wagner Hanns , Zwittnig Gerald , Daller Josef , Fasching Alfred
Published: October 2011

In an early planning phase for the Granitztal tunnel chain, which forms part of the Koralm railway running between Graz and Klagenfurt, Austria, the continuous tunnelling method has been taken into consideration, at least in some sections, in addition to sequential or conventional tunnelling. This paper deals with the investigations that eventually led to the decision to consider both tunnelling methods in the detailed tender design for one section of the tunnel chain, and to let competition decide which tunnelling method to choose.

Für die Tunnelkette Granitztal als Bestandteil der Koralmbahn zwischen Graz und Klagenfurt wurden bereits in einer frühen Planungsphase Überlegungen angestellt, neben der zyklischen Vortriebsmethode auch einen kontinuierlichen Vortrieb – zumindest in Teilbereichen – in Erwägung zu ziehen. Der vorliegende Beitrag befasst sich mit den Untersuchungen, die schließlich zur Entscheidung geführt haben, im Detailprojekt für einen Abschnitt der Tunnelkette beide Vortriebsmethoden durchzuplanen und hier die Entscheidung für die Vortriebsmethode dem Wettbewerb zu überlassen.
Flexibility in embodied lexical‐semantic representations
Authors: van Dam Wessel O. , van Dijk Margriet , Bekkering Harold , Rueschemeyer Shirley‐Ann
Published: October 2011

According to an embodied view of language comprehension, language concepts are grounded in our perceptual systems. Evidence for the idea that concepts are grounded in areas involved in action and perception comes from both behavioral and neuroimaging studies (Glenberg [1997]: Behav Brain Sci 20:1‐55; Barsalou [1999]: Behav Brain Sci 22:577‐660; Pulvermueller [1999]: Behav Brain Sci 22:253‐336; Barsalou et al. [2003]: Trends Cogn Sci 7:84‐91). However, the results from several studies indicate that the activation of information in perception and action areas is not a purely automatic process (Raposo et al. [2009]: Neuropsychologia 47:388‐396; Rueschemeyer et al. [2007]: J Cogn Neurosci 19:855‐865). These findings suggest that embodied representations are flexible. In these studies, flexibility is characterized by the relative presence or absence of activation in our perceptual systems. However, even if the context in which a word is presented does not undermine a motor interpretation, it is possible that the degree to which a modality‐specific region contributes to a representation depends on the context in which conceptual features are retrieved. In the present study, we investigated this issue by presenting word stimuli for which both motor and visual properties (e.g., Tennis ball, Boxing glove) were important in constituting the concept. Conform with the idea that language representations are flexible and context dependent, we demonstrate that the degree to which a modality‐specific region contributes to a representation considerably changes as a function of context. Hum Brain Mapp 33:2322–2333, 2012. © 2011 Wiley Periodicals, Inc.
Stagnation‐point flow of Maxwell fluid with magnetic field and radiation effects
Authors: Hayat T. , Rafique Ansa , Malik M.Y. , Obaidat S.
Published: October 2011

The effect of heat transfer on the steady two‐dimensional stagnation point flow of a Maxwell fluid over a stretching sheet is discussed. The fluid is electrically conducting in the presence of a uniform applied magnetic field. The radiation effect in the energy equation is taken into account. The arising nonlinear problem is solved by a homotopy analysis method (HAM). Convergence of the series solutions is checked. The values of skin friction coefficient and local Nusselt number have been computed and discussed. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.20385
Shifting Native Chemical Ligation into Reverse through N→S Acyl Transfer
Authors: Macmillan Derek , Adams Anna , Premdjee Bhavesh
Published: October 2011

Peptide thioester synthesis by N→S acyl transfer is being intensively explored by many research groups the world over. Reasons for this likely include the often straightforward method of precursor assembly using Fmoc‐based chemistry and the fundamentally interesting acyl migration process. In this review we introduce recent advances in this exciting area and discuss, in more detail, our own efforts towards the synthesis of peptide thioesters through N→S acyl transfer in native peptide sequences. We have found that several peptide thioesters can be readily prepared and, what’s more, there appears to be ample opportunity for further development and discovery.
Oxidoreductase activity of multifunctional monoclonal antibody B13‐DE1
Authors: Messerschmidt Katrin , Degen Janine , Micheel Burkhard
Published: October 2011

The monoclonal antibody B13‐DE1 binds fluorescein, several fluorescein derivatives, and three peptide mimotopes. Our results revealed that this antibody also catalyzed the redox reaction of resazurin to resorufin, which are both structurally related to fluorescein. By using sodium sulfite as a reducing agent, the antibody B13‐DE1 lowered the activation energy of this reaction. The Michaelis–Menten constant and turnover number of the catalyzed reaction were determined as 4.2 µmol/l and 0.0056 s−1, respectively. Because the results showed that fluorescein inhibited the catalytic activity of the antibody, we assume that the antigen‐binding site and the catalytic active site are identical. Copyright © 2011 John Wiley & Sons, Ltd.
Survey of the 2009 commercial optical biosensor literature
Authors: Rich Rebecca L. , Myszka David G.
Published: October 2011

We took a different approach to reviewing the commercial biosensor literature this year by inviting 22 biosensor users to serve as a review committee. They set the criteria for what to expect in a publication and ultimately decided to use a pass/fail system for selecting which papers to include in this year's reference list. Of the 1514 publications in 2009 that reported using commercially available optical biosensor technology, only 20% passed their cutoff. The most common criticism the reviewers had with the literature was that “the biosensor experiments could have been done better.” They selected 10 papers to highlight good experimental technique, data presentation, and unique applications of the technology. This communal review process was educational for everyone involved and one we will not soon forget. Copyright © 2011 John Wiley & Sons, Ltd.
Exploring variation in binding of Protein A and Protein G to immunoglobulin type G by isothermal titration calorimetry
Authors: Lund Line Naomi , Christensen Trine , Toone Eric , Houen Gunnar , Staby Arne , St. Hilaire Phaedria Marie
Published: October 2011

Bacterial Protein A (PrtA) and Protein G (PrtG) are widely used for affinity purification of antibodies. An understanding of how PrtA and PrtG bind to different isotypes of immunoglobulin type G (IgG) and to their corresponding Fc fragments is essential for the development of PrtA and PrtG mimetic ligands and for the establishment of generic processes for the purification of various antibodies. In this paper, the interactions between the two IgG‐binding proteins and IgG of two different subclasses, IgG1 and IgG4, as well as their analogous Fc fragments have been studied by isothermal titration calorimetry. The results indicate that both protein ligands bind IgG and Fc fragments strongly with Ka values in the range of 107–108 M−1 and for both ligands, the interaction with both IgG isotypes is enthalpically driven though entropically unfavorable. Moreover, variation in the standard entropic and standard enthalpic contribution to binding between the two isotypes as well as between IgG and Fc fragment implies that the specific interaction with PrtA varies according to IgG isotype. In contrast to PrtA, PrtG bound to F(ab')2 fragment with a Ka value of 5.1 × 105 M−1; thus underscoring the usefulness of PrtA as a preferred ligand for generic antibody purification processes. Copyright © 2011 John Wiley & Sons, Ltd.
Modelling the interaction between the p53 DNA‐binding domain and the p28 peptide fragment of Azurin
Authors: Santini Simona , Bizzarri Anna Rita , Cannistraro Salvatore
Published: October 2011

Recent experimental data reveal that the peptide fragment of Azurin called p28, constituted by the amino acid residues from 50 to 77 of the whole protein, retains both the Azurin cellular penetration ability and antiproliferative activity. p28 is hypothesized to act by stabilizing the well‐known tumour suppressor p53 via a pathway independent from the oncogene Mdm2, which is the main p53 down‐regulator, with its anticancer potentiality being probably connected with the binding of its amino acid residues 11 to 18 to p53. However, the p28 mode of action has not been completely elucidated yet, mostly because the details of the p28 interaction with p53 are still unknown. In the present study, computational docking modelling supported by cluster analysis, molecular dynamics simulations and binding free energy calculations have been performed to model the interaction between the DNA‐binding domain (DBD) of p53 and the p28 fragment. Since the folding state of p28 when interacting with p53 inside the cell is not known, both the folded and the unfolded structures of this peptide have been taken into consideration. In both the cases, we have found that p28 is able to form with DBD a complex characterized by favourable negative binding free energy, high shape complementarity, and the presence of several hydrogen bonds at the interface. These results suggest that p28 might exert its anticancer action by hampering the binding of ubiquitin ligases to DBD, susceptible to promoting the p53 proteasomal degradation. Copyright © 2011 John Wiley & Sons, Ltd.
Synthetic signal injection using a single radiofrequency channel
Authors: Marro Kenneth I. , Lee Donghoon , Shankland Eric G. , Mathis Clinton M. , Hayes Cecil E.
Published: October 2011

Purpose:

To demonstrate that, when injecting an artificial reference signal for quantitation purposes, the real and artificial signals can be acquired separately, using a single radiofrequency (RF) channel, with no loss of fidelity. Conversion of MR signals to units of concentration can be simplified by injection of a precalibrated, artificial reference signal, or pseudo‐signal. In previous implementations, the pseudo‐signal was acquired simultaneously with the real signals arising from the sample and this requires a second, integrated RF channel.

Materials and Methods:

We used in vivo spectroscopy and in vitro imaging measurements to test the validity of the separate acquisition method.

Results:

There was very strong correlation (r = 0.94; P = 0.02) between the in vivo concentrations determined with separate and simultaneous acquisition methods. The in vitro measurements validated that the separate acquisition method compensates for differences in coil loading conditions as well as the simultaneous acquisition method.

Conclusion:

Separate acquisition eliminates the need for a second RF channel, which allows easier implementation at sites that have only one channel available, and relaxes the constraints on the number and amplitude of pseudo‐signals. This flexibility can be exploited to increase the signal to noise ratio of the pseudo‐signal and reduce variability when making the conversion to units of concentration. J. Magn. Reson. Imaging 2011. © 2011 Wiley Periodicals, Inc.
Measurement of knee joint gaps without bone resection: “Physiologic” extension and flexion gaps in total knee arthroplasty are asymmetric and unequal and anterior and posterior cruciate ligament resections produce different gap changes
Authors: Nowakowski Andrej Maria , Majewski Martin , Müller‐Gerbl Magdalena , Valderrabano Victor
Published: October 2011

General agreement is that flexion and extension gaps should be equal and symmetrical in total knee arthroplasty (TKA) procedures. However, comparisons using a standard TKA approach to normal knee joints that have not undergone bone resection are currently unavailable. Since bony preparation can influence capsule and ligament tension, our purpose was to perform measurements without this influence. Ten normal cadaveric knees were assessed using a standard medial parapatellar TKA approach with patellar subluxation. Gap measurements were carried out twice each alternating 100 and 200 N per compartment using a prototypical force‐determining ligament balancer without the need for bony resection. Initial measurements were performed in extension, followed by 90° of flexion. The ACL was then resected, and finally the PCL was resected, and measurements were carried out in an analogous fashion. In general, the lateral compartment could be stretched further than the medial compartment, and the corresponding flexion gap values were significantly larger. ACL resection predominantly increased extension gaps, while PCL resection increased flexion gaps. Distraction force of 100 N per compartment appeared adequate; increasing to 200 N did not improve the results. © 2011 Orthopaedic Research Society. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:522–527, 2012
Point mass insertion on the real line and non‐exponential perturbation of the recursion coefficients
Authors: Wong Manwah Lilian
Published: October 2011

We present the construction of a probability measure dγ with compact support on \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathbb {R}$\end{document} such that adding a discrete pure point results in changes in the recursion coefficients without exponential decay.
Gas phase basicities of polyfunctional molecules. Part 3: Amino acids
Authors: Bouchoux Guy
Published: October 2011

The present article is the third part of a general overview of the gas‐phase protonation thermochemistry of polyfunctional molecules (first part: Mass Spectrom. Rev., 2007, 26:775‐835, second part: Mass Spectrom. Rev., 2011, in press). This review is devoted to the 20 proteinogenic amino acids and is divided in two parts. In the first one, the experimental data obtained during the last 30 years using the equilibrium, thermokinetic and kinetic methods are presented. A general re‐assignment of the values originating from these various experiments has been done on the basis of the commonly accepted Hunter & Lias 1998 gas‐phase basicity scale in order to provide an homogeneous set of data. In the second part, theoretical investigations on gaseous neutral and protonated amino acids are reviewed. Conformational landscapes of both types of species were examined in order to provide theoretical protonation thermochemistry based on the truly identified most stable conformers. Proton affinities computed at the presently highest levels of theory (i.e. composite methods such as Gn procedures) are presented. Estimates of thermochemical parameters calculated using a Boltzmann distribution of conformers at 298K are also included. Finally, comparison between experiment and theory is discussed and a set of evaluated proton affinities, gas‐phase basicities and protonation entropies is proposed. © 2011 Wiley Periodicals, Inc. Mass Spec Rev 31:391–435, 2012
Teacher and Parent Ratings of Seven–Year–Old Children'S Personality and Psychometrically Assessed Cognitive Ability
Authors: Lönnqvist Jan–Erik , Vainikainen Mari–Pauliina , Verkasalo Markku
Published: October 2011

We linked seven–year–old children's personality ( n = 406), as rated by both teachers and parents, to a wide array of cognitive ability measures. Besides (i) providing descriptive data on the associations between childhood personality and cognitive ability, we (ii) investigated the benefits of having multiple informants provide personality ratings and (iii) examined the recent proposition that the general factor of intelligence be partialled out of associations between personality and narrower domains of intelligence. In a regression model, the shared variance of teacher and parent ratings of personality explained 14% of the variance of cognitive ability. Both teacher and parent ratings of Openness to Experience (O) were positively associated with cognitive ability, and both explained unique variance in cognitive ability. Moreover, the associations were stronger the stronger the inter–rater agreement on O. When the unique variances of each perspective and the moderating effect of inter–rater agreement were added to the aforementioned regression model, personality explained 18% of the variance of cognitive ability. Controlling for the general factor of intelligence caused the correlations between personality and performance on the specific cognitive ability measures to diminish to near zero. Copyright © 2011 John Wiley & Sons, Ltd.
Numerical simulations of absorption properties of InP nanowires for solar cell applications
Authors: Kailuweit Peter , Peters Marius , Leene Jack , Mergenthaler Kilian , Dimroth Frank , Bett Andreas W.
Published: October 2011

In this paper, we present results of optical simulations on the absorption of nanowires. The simulation was performed with rigorous coupled wave analysis to determine the potential of nanowires for use in a new kind of nanostructured solar cell. The overall absorption of the solar cell structure was calculated for four different diameters of the nanowires and also in dependence of light wavelength and nanowire period. Absorption modes were observed at distinct wavelengths, but not dependent on the wire period. To derive a local optical generation function for a nanowire solar cell, the spatially resolved absorption profile was modelled for two wire periods. The calculated generation profiles can be readily used as input for an electrical simulation of a nanowire solar cell to calculate its quantum efficiency and the current–voltage characteristics. Copyright © 2011 John Wiley & Sons, Ltd.
Analysis of protein networks in resting and collagen receptor (GPVI)‐stimulated platelet sub‐proteomes
Authors: Wright Bernice , Stanley Ronald G. , Kaiser William J. , Mills Davinia J. , Gibbins Jonathan M.
Published: October 2011

Proteomics approaches have made important contributions to the characterisation of platelet regulatory mechanisms. A common problem encountered with this method, however, is the masking of low‐abundance (e.g. signalling) proteins in complex mixtures by highly abundant proteins. In this study, subcellular fractionation of washed human platelets either inactivated or stimulated with the glycoprotein (GP) VI collagen receptor agonist, collagen‐related peptide, reduced the complexity of the platelet proteome. The majority of proteins identified by tandem mass spectrometry are involved in signalling. The effect of GPVI stimulation on levels of specific proteins in subcellular compartments was compared and analysed using in silico quantification, and protein associations were predicted using STRING (the search tool for recurring instances of neighbouring genes/proteins). Interestingly, we observed that some proteins that were previously unidentified in platelets including teneurin‐1 and Van Gogh‐like protein 1, translocated to the membrane upon GPVI stimulation. Newly identified proteins may be involved in GPVI signalling nodes of importance for haemostasis and thrombosis.
Synthesis and postfunctionalization of well‐defined star polymers via “double” click chemistry
Authors: Boyer Cyrille , Whittaker Michael , Davis Thomas P.
Published: October 2011

In this article, the synthesis and the functionalization of well‐defined, narrow polydispersity (polydispersity index < 1.2) star polymers via reversible addition‐fragmentation chain transfer polymerization is detailed. In this arm first approach, the initial synthesis of a poly(pentafluorophenyl acrylate) polymer, and subsequent, cross‐linking using bis‐acrylamide to prepare star polymers, has been achieved by reversible addition fragmentation chain transfer polymerization. These star polymers were functionalized using a variety of amino functional groups via nucleophilic substitution of pentafluorophenyl activated ester to yield star polymers with predesigned chemical functionality. This approach has allowed the synthesis of star glycopolymer using a very simple approach. Finally, the core of the stars was modified via thiol‐ene click chemistry reaction using fluorescein‐o‐acrylate and DyLigh 633 Maleimide. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Side chain crosslinking of aromatic polyethers for high temperature polymer electrolyte membrane fuel cell applications
Authors: Vöge Andrea , Deimede Valadoula A. , Kallitsis Joannis K.
Published: October 2011

Novel aromatic polymers bearing polar pyridine units in the main chain and side chain crosslinkable hydroxyl and propargyl groups have been successfully synthesized. The polymers have been investigated in terms of their critical properties related to their application in high temperature polymer electrolyte membrane fuel cells, such as doping ability, mechanical properties, and thermal stability. Crosslinked membranes were prepared by direct crosslinking of hydroxyl side chain groups with decafluorobiphenyl used for the first time as a crosslinking agent. However, further functionalization of hydroxyl groups to the propargyl derivative has also led to crosslinked polymers after thermal curing. Both types of crosslinked membranes exhibited higher glass transition temperatures as well as lower doping levels when doped in phosphoric acid compared with the non crosslinked analogs, confirming the formation of a successfully crosslinked network. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Illuminating the early signaling pathway of a fungal light‐oxygen‐voltage photoreceptor
Authors: Peter Emanuel , Dick Bernhard , Baeurle Stephan A.
Published: October 2011

Circadian clocks are molecular timekeepers encountered in a wide variety of organisms, which allow to adapt the cell's metabolism and behavior to the daily and seasonal periods. Their function is regulated by light‐sensing proteins, among which Vivid, a light‐oxygen‐voltage (LOV) sensitive domain of the fungus Neurospora crassa, constitutes one of the most prominent examples. Although the major photochemical and structural changes during the photocycle of this photosensor have been elucidated through experimental means, its signal transduction pathway is still poorly resolved at the molecular level. In this article, we show through molecular dynamics simulation that the primary steps after adduct formation involve a switch of Gln182 in vicinity of the chromophore FAD (flavin–adenine–dinucleotide), followed by a coupling between the Iβ‐ and Hβ‐strands through H‐bond formation between Gln182 and Asn161 as well as subsequent weakening of the H‐bonding interaction between the Iβ‐ and Aβ‐strands. These processes then induce a reorientation of the Aβ‐Bβ‐loop with respect to the protein core as well as a simultaneous contraction of the partially unfolded α‐helix onto the α‐Aβ‐linker at the Ncap. Finally, we demonstrate through additional dimer simulations that the light‐induced conformational changes, observed in the monomeric case, play a decisive role in controlling the dimerization tendency of Vivid with its partner domains and that the light‐state homodimer shows a much larger affinity for aggregation than the dark state. Proteins 2012. © 2011 Wiley Periodicals, Inc.
Inhibition of chlamydial class Ic ribonucleotide reductase by C‐terminal peptides from protein R2
Authors: Öhrström Maria , Popović‐Bijelić Ana , Luo Jinghui , Stenmark Pål , Högbom Martin , Gräslund Astrid
Published: October 2011

Chlamydia trachomatis ribonucleotide reductase (RNR) is a class Ic RNR. It has two homodimeric subunits: proteins R1 and R2. Class Ic protein R2 in its most active form has a manganese–iron metal cofactor, which functions in catalysis like the tyrosyl radical in classical class Ia and Ib RNRs. Oligopeptides with the same sequence as the C‐terminus of C. trachomatis protein R2 inhibit the catalytic activity of C. trachomatis RNR, showing that the class Ic enzyme shares a similar highly specific inhibition mechanism with the previously studied radical‐containing class Ia and Ib RNRs. The results indicate that the catalytic mechanism of this class of RNRs with a manganese–iron cofactor is similar to that of the tyrosyl‐radical‐containing RNRs, involving reversible long‐range radical transfer between proteins R1 and R2. The competitive binding of the inhibitory R2‐derived oligopeptide blocks the transfer pathway. We have constructed three‐dimensional structure models of C. trachomatis protein R1, based on homologous R1 crystal structures, and used them to discuss possible binding modes of the peptide to protein R1. Typical half maximal inhibitory concentration values for C. trachomatis RNR are about 200 µ m for a 20‐mer peptide, indicating a less efficient inhibition compared with those for an equally long peptide in the Escherichia coli class Ia RNR. A possible explanation is that the C. trachomatis R1/R2 complex has other important interactions, in addition to the binding mediated by the R1 interaction with the C‐terminus of protein R2. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Pressure studies on fullerene peapods
Authors: Kuntscher C. A. , Abouelsayed A. , Botos Á. , Pekker Á. , Kamarás K.
Published: October 2011

We carried out pressure‐dependent transmission measurements on single‐walled carbon nanotubes (SWCNTs) filled with C60 molecules, so‐called C60 peapods, in the near‐infrared and visible frequency range, where the optical transitions between the Van Hove singularities of the carbon nanotubes are excited. The pressure‐induced shifts of the optical transitions exhibit an anomaly associated with the deformation of the carbon nanotubes. The results are compared with those for empty SWCNTs. Furthermore, the importance of the pressure transmitting medium used in the measurements is discussed.
Thermal diffusivity of aligned multi‐walled carbon nanotubes measured by the flash method
Authors: Mäklin Jani , Halonen Niina , Toth Géza , Sápi András , Kukovecz Ákos , Kónya Zoltán , Jantunen Heli , Mikkola Jyri‐Pekka , Kordas Krisztián
Published: October 2011

Thermal diffusivity of freestanding catalytic chemical vapor deposition (CCVD) grown multi‐walled carbon nanotube (MWCNT) forests (height of 1.5 and 1.9 mm) was characterized in the temperature range between 25 and 200 °C. Copper and Al‐alloy metal blocks were used as references for validation of the experimental setup. The measurements were carried out along the MWCNT alignment direction with a thermal property analyzer that uses the flash method. The thermal diffusivities measured at room temperature for as‐grown and post‐annealed (2 h at 480 °C in open air) samples were found to be ∼0.45 and ∼0.23 cm2/s, respectively. In both cases, the thermal diffusivity values were slightly decreasing with increasing temperature. The observed decrease in diffusivity after annealing is most probably due to the loss of amorphous carbon in the specimens and also because of the increased defect density in the nanotube walls resulting in a more pronounced phonon scattering in the lattice. The measured thermal diffusivities for as‐grown samples agree with data reported elsewhere for similar MWCNT materials [W. Yi et al., Rev. B 59, 9015 (1999) and T. Borca‐Tasciuc et al., J. Appl. Phys. 98, 054309 (2005)].
CVD growth and processing of graphene for electronic applications
Authors: Kumar Shishir , McEvoy Niall , Kim Hye‐Young , Lee Kangho , Peltekis Nikos , Rezvani Ehsan , Nolan Hugo , Weidlich Anne , Daly Ronan , Duesberg Georg S.
Published: October 2011

The remarkable properties of graphene have potential for numerous applications; however, their exploitation depends on its reliable production. The chemical vapour deposition (CVD) growth of graphene on metal surfaces has become one of the most promising strategies for the production of high quality graphene in a scaleable manner. Here, we discuss graphene growth on nickel (Ni) and copper (Cu) directly from both gaseous hydrocarbons and solid carbon precursors. Further, we discuss in detail the transfer of graphene films to insulating substrates, by direct and polymer supported transfer methods.
Hybrid photovoltaic cells based on ZnO/Sb2S3/P3HT heterojunctions
Authors: Liu C. P. , Wang H. E. , Ng T. W. , Chen Z. H. , Zhang W. F. , Yan C. , Tang Y. B. , Bello I. , Martinu L. , Zhang W. J. , Jha S. K.
Published: October 2011

We demonstrate hybrid photovoltaic (PV) cells based on n–i–p heterojunctions with incorporated zinc oxide (ZnO) films using a sol–gel method. The cells, employing stibnite (Sb2S3), and poly(3‐hexylthiophene) (P3HT) materials, as light absorption layers, constitute an active region in the indium tin oxide (ITO)/ZnO(n)/Sb2S3(i)/P3HT(p)/Ag hybrid structure. Our investigation shows that annealing temperature has a significant effect on both the crystallinity and optical absorption of Sb2S3 films. The near‐intrinsic Sb2S3 films annealed at 300 °C exhibits dark conductivity of 1.42 × 10−7 S cm−1. The performance of PV cells strongly depends on thermal treatment of Sb2S3, and on the thickness of both the Sb2S3 and P3HT layers. Electronic structures of annealed Sb2S3 films was further studied by photoelectron spectroscopy to understand the physics behind.
Positive and negative electrospray ionisation travelling wave ion mobility mass spectrometry and low‐energy collision‐induced dissociation of sialic acid derivatives
Authors: Winkler Wolfgang , Huber Wolfgang , Vlasak Reinhard , Allmaier Günter
Published: October 2011

Mono‐ or oligosaccharide‐containing samples, whether they are derived from biological sources or products of chemical synthesis, are often mixtures of spatial or constitutional isomers. The possibility of characterising or performing quality control on such samples by mass spectrometry is hampered because these isomers cannot be separated by their mass‐to‐charge ratio alone. Therefore, the use of techniques to separate the isobaric sample compounds prior to mass spectrometric characterisation is mandatory. Travelling wave ion mobility separation offers the possibility of separating mixtures based on their compound's collisional cross‐sections in the gas phase and can easily be combined with mass spectrometry for further characterisation. Here, we use 5‐N‐acetylneuraminic acid and several derivatives as model compounds to evaluate the separation power of travelling wave ion mobility spectrometry and present an approach to clearly identify constitutional isomers in mixtures in combination with low‐energy collision‐induced dissociation (CID) in the negative ion mode even if they cannot be completely separated by ion mobility. Copyright © 2011 John Wiley & Sons, Ltd.
Quantitative estimation of circulating metabolites without synthetic standards by ultra‐high‐performance liquid chromatography/high resolution accurate mass spectrometry in combination with UV correction
Authors: Yang Yanou , Grubb Mary F. , Luk Chiuwa E. , Humphreys W. Griffith , Josephs Jonathan L.
Published: October 2011

An early assessment of metabolite exposure in preclinical species can provide quantitative estimation on possible active or toxic metabolites. Frequently, synthetic metabolite standards are not available at the preclinical stage, precluding the quantitation of metabolites by means of calibration curves and quality control (QC) samples. We present here an approach to determine the extent of circulating metabolites using ‘metabolite standards’ generated by in vitro incubations in combination with the correction for mass spectrometry response based on UV response. The study was done by coupling ultra‐high‐performance liquid chromatography (UHPLC) to LTQ‐Orbitrap high‐resolution mass spectrometry, and the quantitation was based on full scan high‐resolution accurate mass analysis in combination with retention time. First, we investigated the separation capacity of a 10.5 min UHPLC method and the quantitative capability of an LTQ‐Orbitrap for full scan accurate mass quantitation by spiking chemical standards of buspirone and its six metabolites in blank plasma. Then we demonstrated the use of a UV correction approach to quantitatively estimate buspirone and its metabolites in plasma samples from a rat pharmacokinetics study. We compared the concentration versus time profiles of buspirone and its six metabolites in rat plasma samples obtained using three different approaches, including using UV correction, using individual standard curves for each metabolite prepared from the synthetic standard, and using a calibration curve of the parent compound buspirone. We demonstrated the estimated metabolite exposure of buspirone using this UV correction approach resulted in rank ordering of metabolite exposure within three‐fold of the value obtained with metabolite standards, in contrast to eight‐fold without UV correction. The approach presented in this paper provides a practical solution to an unmet bioanalytical need for quantitative information on metabolites without standards in preclinical in vivo studies. Copyright © 2011 John Wiley & Sons, Ltd.
Study of liquid chromatography/electrospray ionization mass spectrometry matrix effect on the example of glyphosate analysis from cereals
Authors: Kruve Anneli , Auling Ragne , Herodes Koit , Leito Ivo
Published: October 2011

Glyphosate is one of the most common pesticides used in the pre‐harvest treatment of cereals. This paper examines the matrix effect of glyphosate liquid chromatography/electrospray ionization mass spectrometric (LC/ESI‐MS) analysis in wheat and rye. The matrix effect (ionization suppression) was found to be dependent on sample particle size taken for the extraction. If samples are ground to very small particles severe ionization suppression occurs. For lower glyphosate contents (<1 mg/kg) the signal may even be suppressed by more than 90%. The matrix effect was found to be dependent on the matrix – rye showed significantly stronger ionization suppression than wheat, although these matrices are not very different. The matrix effect also depends on the concentration of glyphosate in the post‐extraction spiked samples. It is demonstrated that the isotope‐labelled standard 13C2‐glyphosate undergoes different ionization suppression than glyphosate and is therefore not efficient in compensating for matrix effect. At the same time the extrapolative dilution approach allows to efficiently compensate for matrix effect. Copyright © 2011 John Wiley & Sons, Ltd.
Effects of pre‐treatment on the nitrogen isotope composition of Japanese black pine (Pinus thunbergii) tree‐rings as affected by high N input
Authors: Larry Lopez Caceres M. , Mizota Chitoshi , Yamanaka Toshiro , Nobori Yoshihiro
Published: October 2011

Temporal changes in the acquisition of nitrogen (N) are recorded in tree‐rings together with unique N isotopic values. Some debate continues regarding the importance of wood pre‐treatment in isotope analysis and, thus, this study focuses on the removal of labile components to determine the intrinsic nature of N in tree‐rings. The total concentration and stable isotopic value of N in annual tree‐rings were determined for two cores from Japanese black pine (Pinus thunbergii) from areas colonized by black cormorant (Phalacrocorax carbo). One core sample was also collected from a control site, without cormorants. Sharp increases in tree‐ring δ15N values associated with migration of the cormorant population indicate positive incorporation of N from soils, whereas a less pronounced trend was observed for ring samples for periods without or substantially less migration, and for those obtained from the control site. All labile N components were removed by repeated extraction with toluene/ethanol (1:1) solution. Radial translocation of labile N is limited in tree‐rings from Japanese black pine, providing intrinsic records on N acquisition. The difference in N isotopic values (up to 7.0‰) following pre‐treatment was statistically significant for trees affected by the avian colony, whereas the pre‐treatment of the control samples did not influence N values. The implication is that in agreement with previous studies pre‐treatment is not necessary when trees are exposed to natural N concentrations in the soil but the removal of enriched δ15N labile components is necessary when woody plants are exposed to unusually high inputs of N into soils. However, the temporal trend in tree‐ring δ15N series of the avian N affected trees did not change. Thus, if the priority is not the value but the trend then pre‐treatment is not necessary. Copyright © 2011 John Wiley & Sons, Ltd.
Robust adaptive neural network control for environmental boundary tracking by mobile robots
Authors: Sun Tairen , Pei Hailong , Pan Yongping , Zhang Caihong
Published: October 2011

The paper addresses the problem of environmental boundary tracking for the nonholonomic mobile robot with uncertain dynamics and external disturbances. To do environmental boundary tracking, a reference velocity is designed for the nonholonomic mobile robot. In this paper, a radial basis function neural network (NN) is used to approximate a nonlinear function containing the uncertain model terms and the elements of the Hessian matrix of the environmental concentration function. Then, the NN approximator is combined with a robust control to construct a robust adaptive NN control for the mobile robot to track the desired environment boundary. It is proved that the tracking error can be guaranteed to converge to zero in the ultimate. Simulation results are presented to illustrate the stability of the robust adaptive control. Copyright © 2011 John Wiley & Sons, Ltd.
HABITAT SUITABILITY MODELLING AT MESOHABITAT SCALE AND EFFECTS OF DAM OPERATION ON THE ENDANGERED JúCAR NASE, PARACHONDROSTOMA ARRIGONIS (RIVER CABRIEL, SPAIN)
Authors: Costa R. M. S. , Martínez‐Capel F. , Muñoz‐Mas R. , Alcaraz‐Hernández J. D. , Garófano‐Gómez V.
Published: October 2011

Habitat degradation has reduced the complexity of the Mediterranean streams in Spain and contributed to decreasing the historical range of the endangered Júcar nase, Parachondrostoma arrigonis. This species is endemic to the Júcar River Basin (Spain), and most of its populations live in the Cabriel River, which is divided into two segments by the large Contreras Dam. The main objective of this study was to develop a multivariate habitat suitability model (HSM) for this species that can be used to evaluate environmental flows and water management scenarios for the Cabriel River. We first assessed the fish densities (from 2006 to 2008) and compared the habitat characteristics and variability among eight study sites based on the physical characteristics of hydromorphological units (HMUs) or mesohabitats. The abundance of the Júcar nase then was related to the HMU type, and generalized additive models of fish abundance were developed for the sites for both small and large fish. Both models showed acceptable or good performance (adjusted R2 of 69.4 for small fish and 72.4 for large fish), and fish abundance was used as an indicator of potential habitat quality [‘potential nase habitat’ (PNH)] for the Júcar nase. The final step was to apply the HSM to evaluate environmentally friendly flow regimens. Hydraulic simulations were used to estimate the PNH under two flow regimen scenarios and in the actual flow regimen for the regulated study site located below the large dam. This article supports the need for new management actions in the Cabriel River, such as implementation of an environmental flow regimen, and illustrates a procedure for the practical application of habitat selection models at the mesohabitat scale. Copyright © 2011 John Wiley & Sons, Ltd.
Tannin‐osmium conductive staining of biological specimens for non‐coated scanning electron microscopy
Authors: Murakami T.
Published: October 2011

Osmication of biological specimens with a mixture of tannic acid, guanidine hydrochloride, arginine hydrochloride and glycine imparted sufficient electron conductivity to permit SEM observations of non‐coated samples. No charging was noted at 25 kV acceleration voltage and 1 × 10−10 A specimen current in rat kidney specimens. The foot‐processes of the glomerular podocytes were clearly visible without metal coating. This tannin‐osmium method even allowed block staining and enabled continuous observations during and after dissection in the SEM.
Cutting teeth in the SEM
Authors: Boyde A.
Published: October 2011

An SEM was used to observe and record dental tissues as they were being cut. Sound human deciduous and permanent teeth were stored in 70% ethanol until required, then soaked in water, superficially dried and screwed to the SEM specimen stage through small drill holes made when they were wet. Many specimens were frozen and studied at cryogenic temperatures so that they would not become dehydrated. Edges used to cut the teeth included steel and tungsten carbide fashioned to resemble clinical cutting instruments, and diamond ultramicrotome knives and burs. The cutting tools were held either in a micromanipulator or a rigid tool post clamped to the specimen stage. The finest control was obtained by moving the specimen with the usual stage controls. SEM was conducted at 3 or 5 kV using TV speed scanning on the uncoated samples. All experiments were video‐taped. 3‐D control was difficult with a mono image and a real‐time stereo system was therefore developed.

Continuous, flowing sections of enamel could be obtained using diamond knives to cut the prism‐free, surface zone tangentially. Thin sections of dentine, cement and bone curled up as they were cut, thus demonstrating permanent deformation. Subsurface enamel always fractured as it was cut, either locally as the tissue passed over the knife edge or tore out beneath the plane of the knife or by larger fragments cleaving off at larger distances ahead of the knife. Appearances were characteristic of prism orientation with respect to cutting direction. No anisotropy of cutting behaviour was found with dentine or bone: These tissues only fractured when thicker sections were taken.

The SEM methods employed here can be usefully applied in the study of other materials.
Membrane blisters: A fixation artifact a study in fixation for scanning electron microscopy
Authors: Shelton E. , Mowczko W. E.
Published: October 2011

It is been shown by scanning electron microscopy that fixation in glutaraldehyde followed by fixation in osmium tetroxide results in the presence of membrane blisters on the surface of a variety of cells. Fixation in glutaraldehyde alone or osmium tetroxide alone does not result in such extensive artifacts. The blisters, usually 0.2–0.6 μm in diameter, are seen by transmission electron microscopy to be membrane‐bound, virtually empty vesicles. It is concluded that the optimum preservation of the cell surface for scanning electron microscopy is provided by fixation in glutaraldehyde alone.
SEM imaging of the cell structure of dislocation networks in cold worked cu single crystals
Authors: Schmidt P. F. , Grewe H. G. , Pfefferkorn G.
Published: October 2011

In certain metallurgical applications of SEM, such as the observation of deformation effects, and the recovery and recrystallization processes in bulk specimens, it is of special interest to obtain information about local inhomogeneities of the dislocation densities in a sample. This can be obtained using TEM on thin foils. Previously information on distortion in cold‐worked specimens was obtained by measuring the dependence of the deterioration of the resolution of the selected area channelling patterns (SACP) on the degree of deformation. This method, however, is not applicable to highly deformed materials.

Direct SEM imaging of the cell structure of the dislocation network has been achieved without resolving single dislocations by using a suitable arrangement of specimen and detector, such that only backscattered electrons (BSE) leaving the surface at a large angle to the normal contribute to the image signals. The signal‐to‐noise ratio was improved to the degree that it was possible 1) to image the cell structure of the dislocation network and 2) on heating the specimens, to record the growth of recrystallized regions with TV‐frame frequency.

The imaging of the cell structure gives qualitative information about the degree of crystal deformation and the crystallographic direction of grain boundary motion during recrystallization.
A fast fourier transform (FFT) program for a programmable pocket calculator TI 59
Authors: Schwarz W.
Published: October 2011

This paper presents an FFT‐program written for the use of the programmable pocket calculator of Texas Instruments TI 59. The program consists of the following routines: Input/output; FFT forward and inverse; shuffling and a routine that converts the FFT‐coefficients in case that real numbers were put in. The maximal number of input data is 32 complex or 64 real data. Listings of all routines are given and the program handling is described. Peak sharpening and removal of background (PARG) are examples to demonstrate the handling of routines.
Secondary electron emission in the scanning electron microscope
Authors: Moncrieff D. A. , Barker P. R.
Published: October 2011

The secondary electron emission induced by electrons in the energy range 2.5–25 keV was measured in a SEM. Values of the emission coefficient for C, Al, Cu, Mo, Ag and Au are presented showing that it varies systematically with atomic number. The coefficient is still appreciable at 25 keV beam energy. The signal from the secondary electron collector in the SEM includes large contributions from sources other than secondary electron emission from the specimen. These contributions are discussed and their relative importance measured.

Physics Abstracts classification numbers: 0.690, 8.900
Design and construction of an atmospheric or environmental SEM (part 1)
Authors: Daniatos G. D.
Published: October 2011

Progress in designing and constructing an atmospheric or environmental scanning electron microscope (SEM) is reported. The introduction of vacuum pumping between the objective and pressure limiting aperture has allowed the use of relatively large pressure limiting apertures, i.e., up to 57 μm for operation at atmospheric pressure or up to 400 μm for operation at saturation water vapour pressure and room temperature. The imaging obtained has been considerably improved by these developments. The first part of experimentation and analysis on the vacuum characteristics of the new system together with different detection configurations is also presented.
Sources of contamination in electron optical equipment
Authors: Love G. , Scott V. D. , Dennis N. M. T. , Laurenson L.
Published: October 2011

Contamination in electron optical equipment may occur in the form of carbonaceous deposit on the specimen undergoing analysis or condensation and/or polymerisation of extraneous matter upon other components of the instrument. Almost without exception these effects are undesirable and in this paper we review sources of contamination and discuss methods of minimising the problem.