bluuebunny/crossref_metadata_2025 huggingface dataset:
An antibacterial surface coating composed of PAH/SiO2 nanostructurated films by layer by layer
Authors: Urrutia Aitor , Rivero Pedro J. , Ruete Leyre , Goicoechea Javier , Fernández‐Valdivieso C. , Arregui Francisco J. , Matías Ignacio R.
Published: August 2010

In this work we propose a novel antibacterial coating composed of SiO2 and the polymer Poly(allylamine hydrochloride) (PAH). The coating was fabricated by the technique Layer‐by‐Layer (LbL). This technique has already been used in previous works, and it has the advantage that it allows to control the construction of nanosized and well organized multilayer films. Here, the new nanotexturized LbL SiO2 surface acts as antibacterial agent. The fabricated coatings have been tested in bacterial cultures of genus Lactobacillus to observe their antibacterial properties. It has been demonstrated these PAH/SiO2 coating films have a very good antimicrobial behaviour against this type of bacteria. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carbon nanocapsules: blocking materials inside carbon nanotubes
Authors: Tobias Gerard , Ballesteros Belén , Green Malcolm L. H.
Published: August 2010

Filled carbon nanotubes are of increased interest due to their potential in a wide variety of applications including drug delivery systems, data storage and nano‐electronic devices. Bulk filling of carbon nanotubes always results in samples containing a large amount of unwanted material external to the SWNT walls. For the envisaged applications of filled carbon nanotubes it is necessary to remove the external materials whilst preserving the material encapsulated in the SWNTs. We have observed that this can be achieved by closing the ends of the SWNTs or by using fullerenes to “cork” open‐ended SWNTs. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient physics‐based compact model for the Schottky barrier carbon nanotube FET
Authors: Najari Montassar , Frégonèse Sébastien , Maneux Cristell , Mnif Hasséne , Zimmer Thomas , Masmoudi Nouri
Published: August 2010

This paper presents a computationally efficient physics‐based compact model for the Schottky barrier CNTFET. This compact model captured a number of features exhibited by these transistors such as ballistic transport and channel potential variation with respect to channel charge. Also quantum capacitance is pointed out. A new analytical model of the channel charge is presented here. The compact model accuracy is verified within its range of validity. To investigate on the SB influence, two classical circuit applications are simulated; the logical inverter and the 5 stages ring oscillator (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mid‐infrared detectors based on carbon nanotube films
Authors: Maine Sylvain , Koechlin Charlie , Fleurier Romain , Haidar Riad , Bardou Nathalie , Dupuis Christophe , Attal‐Trétout Brigitte , Mérel Philippe , Deschamps Joël , Loiseau Annick , Pelouard Jean‐Luc
Published: August 2010

In this paper we report the fabrication and characterization of single wall carbon nanotube film based devices. Carbon nanotubes (CNT) film is deposited on a silica substrate and usual clean room processes have been used to make Pt‐electrodes on top of it and to pattern the CNT film. The obtained devices have been used to measure the evolution of the temperature coefficient of resistance (TCR) as a function of temperature. At room temperature the TCR is –0.2%K‐1 and becomes even more important as the temperature goes down. Moreover the optical response in atmospheric band II and band III have been investigated at room temperature showing a variation of the device resistance up to 0.2% for an irradiance of ∼100 mW/cm2 in the 3–5 µm range. Such results are very promising for application of CNT films in bolometers for thermal infrared detection (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic behaviour of non‐contacting Ni nanoparticles encapsulated in vertically aligned carbon nanotubes
Authors: García J. A. , Bertran E. , Elbaile L. , García‐Céspedes J. , Svalov A.
Published: August 2010

Magnetic properties of carbon nanotubes (CNT) obtained by plasma‐enhanced chemical vapour deposition (PECVD) have been studied. The growth of these nanotubes has been activated from Ni catalyst nanoparticles. Samples consist of Ni nanoparticles encapsulated at the tip of vertically aligned multiwalled carbon nanotubes (VACNTs) forming an homogeneous and dense large area monolayer of isolated (non‐contacting) nanoparticles. The magnetic characterisation has been performed in the temperature range of 5‐300 K with magnetic fields up to 9 T. The results show that the wide size range (30‐180 nm) of the particles originates the coexistence of blocked and superparamagnetic particles and leads to the strong ferromagnetic behaviour of the whole assembly. The coercivity decreases monotonically with increasing temperature and the value for the intrinsic coercivity is 225 Oe. The encapsulation of Ni nanoparticles by VACNTs preserves them from aggregation. This makes possible to tune the coercivity by controlling size distribution of particle monolayers. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of low‐dimensional carbon nanostructures: an efficient approach based on chemical criteria
Authors: Mercuri Francesco
Published: August 2010

Recently, the properties of nanostructured carbon materials, like carbon nanotubes (CNTs) and graphene, have been the subject of in‐depth investigations in view of their potential use in nanotechnology. Most of the interest concerning nanostructured carbon materials is related to the peculiarities of their electronic structure, which is constituted mainly by a complex network of π‐conjugated bonds. Details of the electronic structure play a crucial role in the application of such materials as nanostructured building‐blocks for molecular electronics and in functionalization processes, where the CNTs and graphenes undergo chemical reactions. However, the particular structural and electronic features of nanostructured carbon pose significant problems to computational modeling. Recent work indicated the extension of classical organic chemistry concepts to the case of low‐dimensional nanostructured carbon materials as a successful approach to obtain an accurate and consistent description of the electronic structure of the hexagonal carbon atom network. In this work we develop a novel approach to investigations on the stability and on electronic and chemical properties of nanotubes and graphenes and related compounds. Our approach is based on the definition of suitable models of the system under study starting from chemical considerations. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and Raman characterization of nanogranular BaTiO3‐NiFe2O4 thin films deposited by laser ablation on Si/Pt substrates
Authors: Gonçalves J. R. , Barbosa J. , Sá P. , Mendes J. A. , Rolo A. G. , Almeida B. G.
Published: August 2010

Thin films composed by (BaTiO3)1‐x‐(NiFe2O4)x with different nickel ferrite concentrations (x) have been deposited by pulsed laser ablation on platinum covered Si(001) substrates. The films structure was studied by X‐ray diffraction and Raman spectroscopy. It was found that the NiFe2O4 phase unit cell was expanded along the growth direction of the films, with a lattice parameter that increased with increasing NiFe2O4 concentration. The opposite behavior was observed on the BaTiO3 phase, with an expansion of its unit cell that lowered with increasing x. The presence of the strain in the films induced a redshift of the Raman peaks of NiFe2O4 that decreased with increasing NiFe2O4 concentration. Cation disorder in the nickel ferrite was observed for lower x, where the nanograins are more isolated and subjected to more strain, which was progressively decreased for higher NiFe2O4 content in the films. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low temperature STM/STS study of silicon nanowires grown on the Ag(110) surface
Authors: Ronci Fabio , Colonna Stefano , Cricenti Antonio , De Padova Paola , Ottaviani Carlo , Quaresima Claudio , Aufray Bernard , Le Lay Guy
Published: August 2010

In this paper we report a Scanning Tunneling Microscopy (STM) and Spectroscopy (STS) study as a function of temperature (ranging from room to liquid helium temperature) of the Si/Ag(110) surface at different silicon coverage. In particular, partially and fully covered surfaces, both characterized by the presence of highly ordered nanowires, are examined by STM imaging and by STS spectroscopy in order to study the temperature dependence of both the nanowires structure and their peculiar metallic behavior. No evident variation was observed upon cooling from room to liquid helium temperature, both in the STM images and in the STS spectroscopy, suggesting that such nanowires maintain the same structure in the investigated temperature range. Empty states differential conductance images show a dramatic evolution as the bias voltage is increased, suggesting that electrons are confined along the direction perpendicular to the nanowires (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of Mn‐doped ZnO/TiO2 multilayer nanostructures grown by pulsed laser deposition
Authors: Khodorov A. , Levichev S. , Chahboun A. , Rolo A. G. , Bernstorff S. , Barradas N. P. , Alves E. , Gomes M. J. M.
Published: August 2010

Mn‐doped ZnO/TiO2 multilayer nanostructures were grown on Si(100) substrates by the pulsed laser deposition technique. Post growing annealing in oxygen or nitrogen atmosphere was performed to improve the crystallinity of the nanostructures. The crystalline structure and morphology of the nanostructures were characterized by Raman scattering, wide angle X‐ray scattering, and grazing incidence small angle X‐ray scattering. Rutherford backscattering and particle induced X‐ray emission analysis were performed to study the composition (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards the explicit computation of Bohm velocities associated to N‐electron wave‐functions with arbitrary spin‐orientations
Authors: Alarcón A. , Cartoixà X. , Oriols X.
Published: August 2010

The direct solution of the many‐particle Schrödinger equation is computationally inaccessible for more than very few electrons. In order to surpass this limitation, one of the authors [X. Oriols, Phys. Rev. Lett. 2007, 98 (066803)] has recently proposed a new model to study electron‐electron correlations from Bohm trajectories associated to time‐dependent wave‐packets solutions of pseudo single‐particle Schrödinger equations. In the aforementioned paper only the orbital exchange interaction is considered assuming that all electrons have the same spin orientation. Then, the many‐particle wave function is a complex Slater determinant of the single‐particle wave‐packets. In the present work the previous formalism is extended to study many‐particle wave functions where the electrons have different spin orientations. The main difficulty to treat N different electron spin orientations with time‐dependent wave‐packets is that one must study all the possible N!N! products of permutations among spin states. To overcome this computationally inaccessible problem, in this article the total wave function is treated as a separated product of two many‐particle wave functions, the first with spin up and the second with spin down. In order to numerically justify this approximation, the Bohm velocity in different antisymmetric total wave‐function scenarios is computed. The computational results confirms the accurate validity of our approximation under a large number of cases (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Erratum: The Fermi surface of a superconductor: OsB2
Authors: Hebbache M.
Published: August 2010

Reference [4] of the Rapid Research Letter by M. Hebbache, published in Phys. Status Solidi RRL 3, 163 (2009), is corrected. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Accuracy of reduced‐grid calculations
Authors: Williamson David L. , Rosinski James M.
Published: August 2010

The accuracy of calculations on reduced grids is examined from a climate modelling perspective. It is demonstrated that an adiabatic Eulerian spectral‐transform model run on an e‐digit grid is accurate to e digits for short integrations. The error introduced by the reduced grid grows as expected for a turbulent atmosphere, and the growth is not accelerated by the reduced grid. The errors from an adiabatic semi‐Lagrangian spectral‐transform model can be significantly larger than those from an Eulerian model because the interpolation required in the semi‐Lagrangian method will not maintain more than a few digits of accuracy. Adiabatic model errors are put in perspective by illustrating errors introduced by arbitrary aspects of model specification such as the longitude of the first grid point. For the Eulerian adiabatic model there appears to be no justification in using a higher‐digit grid than the 2‐digit one. A higher‐digit grid may be desirable for an adiabatic semi‐Lagrangian model. Results from a cosine‐bell advection test are presented. All reduced grids tested have the same error for Eulerian spectral‐transform advection. The semi‐Lagrangian advection shows some increase in error with greater reduction in the grid, but the variation is comparable with the difference in error from choosing different interpolants or different time steps. There is little reason to choose a higher‐digit grid than the 4‐digit grid. In fact the 3‐, 2‐ and 1‐digit grids might be considered satisfactory for semi‐Lagrangian advection. Finally, multiple‐year climate simulations with full and reduced grids are presented. The overall impression is that the mean climates produced by the models run on the reduced grids are all very similar. There is no indication that the reduced grids introduce pathological errors that contaminate the simulations. A few select fields which are particularly sensitive to model changes are shown to quantify the differences, and to indicate that the differences are comparable with those which arise from the natural variability of the model. The results indicate that even a 1‐digit grid is suitable for climate modelling with both Eulerian and semi‐Lagrangian spectral‐transform models.
Break‐up of a stratospheric streamer observed by MST radar
Authors: Vaughan G. , Worthington R. M.
Published: August 2010

The break‐up of a stratospheric streamer over the British Isles is described, using satellite, Mesosphere—Stratosphere—Troposphere (MST) radar and in situ observations together with European Centre for Medium‐Range Weather Forecasts analyses. The streamer started as a thin ribbon of high potential vorticity to the west of the British Isles. As this was strained by the background flow it broke up into a series of mesoscale vortices. MST radar and ozonesonde observations delineated a tropopause fold to the west of the initial streamer, taking the form of a thin layer of stratospheric air embedded in a deep layer of descending upper‐tropospheric air. The fold appears to have been mixed out by small‐scale turbulence as the streamer broke up. This break‐up also generated strong inertia‐gravity waves, which broke just above the tropopause introducing extensive mixing to the lowermost stratosphere. One of the mesoscale vortices returned over the MST radar, showing a very indistinct tropopause typical of a synoptic‐scale cut‐off low. This vortex was also responsible for the development of a rain band on its eastern flank, which brought significant rainfall to the British Isles at a time when the synoptic flow pattern was strongly anticyclonic.
A comprehensive two‐moment warm microphysical bulk scheme. I: Description and tests
Authors: Cohard Jean‐Martial , Pinty Jean‐Pierre
Published: August 2010

A bulk microphysical scheme which predicts the concentrations and mixing ratios of cloud droplets and raindrops is presented. The scheme draws its originality from the use of generalized gamma law as basis functions for the drop size distributions and also from the attention paid to performing analytical integrations of most of the microphysical transfer rates. The numerical representation of each process has been reviewed throughout and specific tests have been made to evaluate separately the accuracy of the scheme compared with a bin‐size model. The scheme, which depends on the specification of a few input parameters shaping the activation spectrum, is incorporated in a three‐dimensional non‐hydrostatic model with some applications given in a companion paper (Part II).
The impact of human activities on the photochemical production and destruction of tropospheric ozone
Authors: Collins W. J. , Derwent R. G. , Johnson C. E. , Stevenson D. S.
Published: August 2010

The spatial and temporal distribution of tropospheric ozone is controlled by transport processes, including advection, convection and dispersion and by stratosphere‐troposphere exchange, surface deposition to the earth's surface and by photochemical production and destruction within the troposphere itself. These processes have been represented in some detail in a global three‐dimensional Lagrangian chemistry (STOCHEM) model which has been used to construct global ozone budgets and identify the main features in the spatial distribution of daily ozone tendencies. The annually and spatially integrated net chemical production of ozone is about twice as large as the stratosphere‐troposphere exchange flux, so that the concentration‐dependent surface deposition balancing term is about three times larger than the stratosphere‐troposphere exchange term. The total production and loss terms for ozone by tropospheric photochemistry are much greater than the net chemical production, with total chemical production about five times larger than the net term. The ozone turnover time is therefore around 30 days, around one tenth of the turnover time due to stratosphere‐troposphere exchange alone. Human activities may influence future tropospheric ozone levels through at least two distinct mechanisms: first, increasing emissions of tropospheric ozone precursor gases: methane, oxides of nitrogen, carbon monoxide and hydrocarbons, leading to increased ozone levels; second, human‐induced climate change may lead to increased temperatures and water vapour concentrations, and hence increased ozone destruction and decreased ozone concentrations.
Development and evaluation of an ensemble forecasting system for coastal storm surges
Authors: Flowerdew Jonathan , Horsburgh Kevin , Wilson Chris , Mylne Ken
Published: August 2010

The overtopping of flood defences by coastal storm surges is a significant threat to life and property. Like all forecasts, storm surge predictions have an associated uncertainty, but this has not been directly predicted by previous operational systems. The Met Office Global and Regional Ensemble Prediction System (MOGREPS), which has recently become operational, provides an explicit sample of the range of atmospheric evolutions consistent with the latest observations. The storm surge ensemble derives a storm surge forecast for each MOGREPS ensemble member, giving an explicit estimate of the risk of reaching significant water levels. The system has now been running for over two years in trial mode, with positive feedback from both Met Office and Environment Agency forecasters. For the surge on 9 November 2007, which received significant media coverage, it produced a clear signal of an abnormal event at the full 54‐hour lead time, with a useful indication of the range of possible water levels. Statistical verification covering two winters demonstrates that the ensemble spread is indeed a reliable indicator of the significantly increased uncertainty associated with large surge events, although the error in more normal situations is dominated by inaccuracies in the separate harmonic tide prediction which is used to convert surge to water level. Probabilistic verification shows some advantage over climatological error distributions, particularly for larger thresholds and longer lead times. Following this successful trial, the system was made operational in December 2009. Copyright © 2010 Royal Meteorological Society and Crown Copyright.
Sea‐land breeze development during a summer bora event along the north‐eastern Adriatic coast
Authors: Prtenjak Maja Telišman , Viher Mladen , Jurković Jadran
Published: August 2010

The interaction of a summer frontal bora and the sea‐land breeze along the north‐eastern Adriatic coast was investigated by means of numerical simulations and available observations. Available measurements (in situ, radiosonde, satellite images) provided model validation. The modelled wind field revealed several regions where the summer bora (weaker than 6 m s−1) allowed sea‐breeze development: in the western parts of the Istrian peninsula and Rijeka Bay and along the north‐western coast of the island of Rab. Along the western Istrian coast, the position of the narrow convergence zone that formed depended greatly on the balance between the bora jets northward and southward of Istria. In the case of a strong northern (Trieste) bora jet, the westerly Istrian onshore flow presented the superposition of the dominant swirled bora flow and local weak thermal flow. It collided then with the easterly bora flow within the zone. With weakening of the Trieste bora jet, the convergence zone was a result of the pure westerly sea breeze and the easterly bora wind. In general, during a bora event, sea breezes were somewhat later and shorter, with limited horizontal extent. The spatial position of the convergence zone caused by the bora and sea‐breeze collision was strongly curved. The orientation of the head (of the thermally‐induced flow) was more in the vertical causing larger horizontal pressure gradients and stronger daytime maximum wind speed than in undisturbed conditions. Except for the island of Rab, other lee‐side islands in the area investigated did not provide favourable conditions for the sea‐breeze formation. Within a bora wake near the island of Krk, onshore flow occurred as well, although not as a sea‐breeze flow, but as the bottom branch of the lee rotor that was associated with the hydraulic jump‐like feature in the lee of the Velika Kapela Mountain. Copyright © 2010 Royal Meteorological Society
Instability of surface‐temperature filaments in strain and shear
Authors: Harvey B. J. , Ambaum M. H. P.
Published: August 2010

The effects of uniform straining and shearing on the stability of a surface quasi‐geostrophic temperature filament are investigated. Straining is shown to stabilize perturbations for wide filaments but only for a finite time until the filament thins to a critical width, after which some perturbations can grow. No filament can be stabilized in practice, since there are perturbations that can grow large for any strain rate. The optimally growing perturbations, defined as solutions that reach a certain threshold amplitude first, are found numerically for a wide range of parameter values. The radii of the vortices formed through nonlinear roll‐up are found to be proportional to θ/s, where θ is the temperature anomaly of the filament and s the strain rate, and are not dependent on the initial size of the filament.

Shearing is shown to reduce the normal‐mode growth rates, but it cannot stabilize them completely when there are temperature discontinuities in the basic state; smooth filaments can be stabilized completely by shearing and a simple scaling argument provides the shear rate required. Copyright © 2010 Royal Meteorological Society
An improved PDF cloud scheme for climate simulations
Authors: Kuwano‐Yoshida Akira , Enomoto Takeshi , Ohfuchi Wataru
Published: August 2010

An efficient grid‐scale cloud scheme for climate simulation is implemented in the atmospheric general circulation model for the Earth Simulator (AFES). The new cloud scheme uses statistical partial condensation using joint‐Gaussian probability distribution functions (PDFs) of the liquid water potential temperature and total water content, with standard deviations estimated by the moist Mellor–Yamada level‐2 turbulence scheme. It also adopts improved closure parameters based on large‐eddy simulations and a revised mixing length that varies with the stability and turbulent kinetic energy. These changes not only enable better representation of low‐level boundary layer clouds, but also improve the atmospheric boundary layer structure. Sensitivity experiments for vertical resolution suggest that O(100–200 m) intervals are adequate to represent well‐mixed boundary layers with the new scheme. The new scheme performs well at relatively low horizontal resolution (about 150 km), although inversion layers near the coast become more intense at a higher horizontal resolution (about 50 km). Copyright © 2010 Royal Meteorological Society
High‐Resolution, Parallel Patterning of Nanoparticles via an Ion‐Induced Focusing Mask
Authors: You Sukbeom , Han Kyuhee , Kim Hyoungchul , Lee Heechul , Woo Chang Gyu , Jeong Changui , Nam Woongsik , Choi Mansoo
Published: August 2010

An ion‐induced focusing mask under the simultaneous injection of ions and charged aerosols generates invisible electrostatic lenses around each opening, through which charged nanoparticles are convergently guided without depositing on the mask surface. The sizes of the created features become significantly smaller than those of the mask openings due to the focusing capability. It is not only demonstrated that material‐independent nanoparticles including proteins can be patterned as an ordered array on any surface regardless of the conductive, nonconductive, or flexible nature of the substrate, but also that the array density can be increased. Highly sensitive gas sensors based on these focused nanoparticle patterns are fabricated via the concept.
Anforderungen an Stahl‐ und Verbundknoten bei Stützenausfall in einem Rahmentragwerk
Authors: Kuhlmann Ulrike , Rölle Lars , Jaspart Jean‐Pierre , Demonceau Jean‐Francois
Published: August 2010

Eine lokale Schädigung innerhalb der Tragstruktur (z. B. Stützenausfall durch Anprall oder Explosion) kann zu einem Versagen der Gesamtstruktur und damit zum Einsturz des Gebäudes führen. Um solch ein globales Versagen durch lokale Schädigung zu vermeiden, muss innerhalb der Tragstruktur eine Umlagerung der Schnittgrößen ermöglicht werden, d. h., es müssen sich alternative Lastpfade ausbilden können. Solch eine Umlagerung, z. B. von einem reinen Biegezustand in einen gemischten Biege‐/Membranspannungszustand, bedingt unter Umständen sehr große Verformungen, die zu großen Deformationen der Anschlüsse führen.

Im Rahmen eines europäischen RFCS‐Forschungsprojektes wurde versucht, mit Hilfe sehr duktiler Anschlussausbildungen die Robustheit von Stahl‐ und Verbundrahmentragwerken zu verbessern. Hauptaugenmerk bei der Konzeption der Anschlüsse war dabei, den Material‐ und Fertigungsaufwand der Anschlüsse so gering wie möglich zu halten und die Umlagerungsmöglichkeiten für außergewöhnliche Bemessungssituationen vornehmlich über das Vorhalten hoher Verformungskapazitäten der Anschlüsse zu aktivieren. Aus diesem Grund wurden hier nachgiebige teiltragfähige Anschlüsse gewählt. Als außergewöhnliche Bemessungssituation wurde in diesem Projekt schwerpunktmäßig der Stützenausfall in einem Rahmentragwerk betrachtet. (RFCS Research Fund for Coal and Steel)

Requirements on steel‐ and composite joints for the load case column removal. Local failure in a structure (e. g. sudden column loss due to impact or explosion) may lead to progressive collapse propagation of the global structural system resulting in a total collapse. To avoid progressive collapse initiated by local damage a redistribution of force from the damaged part of the structure has to be enabled by alternate load paths. Activation of alternate load paths by change of the bearing mechanism from pure bending state to more or less pure membrane state is a measure that is only possible by allowing large deformations resulting in high deformation requirements for the joints.

In the course of an European RFCS research project ductile joint solutions have been developed to improve the robustness as characteristic of the structure. Main focus of the joint design was to obtain the required deformation capacity for accidental design situations mainly from ductile joint and cause at the same time only few additional material and fabrication costs for the joints. As a result semi‐rigid and partial‐strength joint solutions have been chosen. Objectives within the project were to determine requirements of the joints concerning deformation capacity as well as M‐N‐resistance to enable the activation of catenary action for the load case notional column removal.
Anprall und Explosion – Experimentelle Untersuchungen an Verbundbauteilen
Authors: Britner Alexander , Ummenhofer Thomas , Elghazouli Ahmed Y. , Bangert Falko , Dürr André
Published: August 2010

Außergewöhnliche Bauwerksbeanspruchungen aus Explosion und Anprall rücken immer mehr in den Fokus der Bemessung wegen der weltweiten Zunahme terroristischer Anschläge. Der passive Schutz von Bauten gegenüber Terrorattacken gewinnt immer mehr an Bedeutung. Die Auswirkungen solcher dynamischen Belastungen aus Anprall und Explosion unterscheiden sich wegen des dynamischen Systemverhaltens und der Abhängigkeit vom Impulsverlauf erheblich von statischen Belastungen.

Im Rahmen des europäischen RFCS (Research Fund for Coal and Steel)‐Forschungsprojekts COSIMB (Composite Column and Wall Systems for Impact and Blast Resistance) wurden an der Universität Karlsruhe, heute Karlsruher Institut für Technologie (KIT), am Imperial College, London, und bei der HOCHTIEF Construction AG, Frankfurt, Untersuchungen an Verbundstützen und Stützen‐Wand‐Verbundsystemen, bestehend aus höherfestem Stahl und hochfestem Beton, durchgeführt. Die Untersuchungen umfassten sowohl statische als auch dynamische Beanspruchungen. Die realisierten Aufprallgeschwindigkeiten betrugen bis zu 14,5 m/s bei einer Masse des Aufprallfahrzeugs von bis zu 1460 kg. Die aufgebrachten Explosionsbelastungen entsprachen der Druckwelle einer Sprengladung von bis zu 2240 kg TNT‐Äquivalent. Der vorliegende Beitrag beschreibt die Versuchsdurchführung sowie die erhaltenen Ergebnisse.

Blast and impact – Experimental investigations on composite structures. Nowadays civil engineers pay more attention to the extraordinary loads like blast and impact. This trend was set off by the political development after the Cold War when the risk of terrorist attacks increased. The passive protection of the buildings becomes more important. The effects of such loads are not the same as the effect of a static load with the same maximum amplitude. It is a fact that currently used structures are not designed for such extreme events.

Within the European RFCS research project COSIMB experimental study on composite column and wall systems made out of high performance steel and concrete was done. The experimental study includes static and dynamic tests. The impact velocities were up to 14.5 m/s. The mass of the impact moving barrier was up to 1460 kg. The blast loads corresponds to an explosive charge up to 2240 kg TNT. In this paper the performance of the tests and the test results are presented.
Plasma‐induzierte Polymerisation von Acrylaten
Authors: Elsner Christian
Published: August 2010

Plasmen eignen sich zur Erzeugung komplexer Polymere aus einfachen Monomervorstufen. Beispielsweise wird der Prozess der Plasma‐Polymerisation zur Abscheidung dünner polymerer Filme aus der Gasphase genutzt, indem die gasförmigen Polymerprecursoren aktiviert, ionisiert oder fragmentiert werden und sich anschließend zu größeren Molekülkomplexen zusammenlagern. Eine weitere Möglichkeit zur Erzeugung polymerer Strukturen besteht über die Plasma‐induzierte Polymerisation. Hierbei erfolgt die Polymerisation innerhalb einer zuvor auf ein Substrat aufgebrachten Beschichtung. Sie wird initiiert durch reaktive Plasmaspezies in Analogie zu anderen strahleninduzierten Polymerisationen. Ein Vorteil des Plasmaverfahrens ist jedoch die räumliche Verteilung aktiver Spezies, die es ermöglicht, auch prepolymere, flüssige Beschichtungen auf komplex geformten Substraten auszuhärten. In diesem Artikel werden Ergebnisse von Untersuchungen zur Plasma‐induzierten Polymerisation an Acrylaten vorgestellt. In diesem Zusammenhang wird auf Aspekte des Doppelbindungsumsatzes, der Oberflächenenergie und der Mikrostrukturierung eingegangen.
Einfluss der HiPIMS‐Parameter beim PVD‐Verfahren
Authors: Slomski Elena Maja , Scheerer Herbert , Troßmann Torsten , Berger Christina
Published: August 2010

Störstellen in Bauteiloberflächen wirken sich häufig ungünstig auf die Schichtnukleation bei PVD‐Beschichtungen aus. Sie können beim Schichtwachstum zu defekten in der Schichtstruktur führen. Die Konsequenz ist eine Minderung der lokalen Haftfestigkeit, höhere Reibwerte und Fehlstellen in der Schicht. Diese begünstigen in korrosiven Medien die Entstehung von lokalen Korrosionselementen an Defekten.

CrN‐Schichten sind für ihre hohe Härte und ihre guten Verschleißeigenschaften bekannt. Zudem weisen sie eine bessere Korrosionsbeständigkeit als Ti basierte Nitride auf. Die strukturellen und mechanischen Eigenschaften dieser Schichtsysteme können unter anderem durch die Veränderung der Biasspannung und des Stickstoffgehalts während des Schichtwachstums beeinflusst werden.

Durch gezielte Variation dieser Parameter beim reaktiven Magnetronsputtern wurden CrN‐Schichten mit den bevorzugten Kristallgitterstrukturen (111) und (200) abgeschieden, mit dem Ziel, deren Fähigkeit zur Abdeckung von Störstellen zu untersuchen.
Nanotechnologie
Authors: Werner Matthias , Barbré Ingo Matthias , Markanović Mario
Published: August 2010

Nanotechnologie hat sowohl in der Wissenschaft als auch in der Wirtschaft erheblich an Bedeutung gewonnen. Über 4 Milliarden USD an öffentlichen Fördergeldern werden allein in diesem Jahr weltweit für die Nanotechnologieforschung ausgegeben. Verschiedene Publikationen weisen darauf hin, dass nahezu jede Branche in der Zukunft durch Nanotechnologie beeinflusst werden wird. Die Anwendung von kohlenstoffbasierten Materialien – insbesondere Kohlenstoffnanoröhren – wird im Allgemeinen in unterschiedlichen Branchen als eine der wichtigsten Zukunftssektoren angesehen. Trotzdem sind derzeit nur äußerst begrenzte Informationen über die Märkte, die Marktgrößen, die Patentsituation und die Zeitspannen bis zur Kommerzialisierung verfügbar. Exotische kohlenstoffbasierte Materialien, wie z. B. nanokristalline Diamantfilme, weisen physikalisch sehr ähnliche Eigenschaften – wie Kohlenstoffnanoröhren – auf und werden bereits sehr erfolgreich in verschiedenen Nischenmärkten angewendet.
Kollektorbeschichtungen für die EUV‐Lithografie
Authors: Perske Marco , Pauer Hagen , Yulin Sergiy , Trost Marcus , Schröder Sven , Duparré Angela , Feigl Torsten , Kaiser Norbert
Published: August 2010

Die Extrem‐Ultraviolett‐Lithografie (EUVL) bei einer Wellenlänge von 13,5 nm (14‐mal kleiner als bei aktuellen Lithografiesystemen) stellt eine innovative Methode dar, integrierte Schaltkreise mit strukturbreiten ≤ 22 nm herzustellen [1]. Die vorliegende Arbeit demonstriert die erfolgreiche Beschichtung des derzeit weltgrößten Kollektorspiegels für die EUVL mit einem Durchmesser von 660 mm (Abb. 1). Um den geforderten Reflexionsgrad von mehr als 65 % auf dem Kollektor zu realisieren, wurde dieser mit einem hochreflektierenden Interferenzschichtsystem versehen. Die Beschichtung ist mittels DC‐Magnetronsputtertechnologie an der Beschichtungsanlage „NESSY”︁ durchgeführt worden. Der erzielte Reflexionsgrad lag bei mehr als 65 % für Radien bis zu 220 mm. Für Radien zwischen 230 mm und 320 mm nahm der Reflexionsgrad auf 58 % ab. Die angestrebte Wellenlänge blieb über die gesamte Kollektoroberfläche konstant bei (13,50 ± 0,05) nm und liegt somit innerhalb der Spezifikation für die kommerzielle Nutzung.
A fast and reliable routing technique for wireless mesh networks
Authors: Javadi Farshad , Munasinghe Kumudu S. , Jamalipour Abbas
Published: August 2010

In wireless mesh networks (WMNs), real time communications (e.g., Voice over IP (VoIP) and interactive video communications) may often be interrupted as packets are frequently lost or delayed excessively. This usually happens due to the unreliability of wireless links or buffer overflows along the routing paths. The mesh connectivity within the WMN enables the capability to enhance reliability and reduce delay for such applications by using multiple paths for routing their packets. The vital components in multi‐path routing for achieving this are the pre‐determined formation of paths and the technique that the paths are deployed for packet traversal. Therefore, we propose a novel multi‐path routing protocol by introducing a new multi‐path organization and a traffic assignment technique. The designed technique dubbed as FLASH (Fast and reLiAble meSH routing protocol) discovers one primary path between a pair of source and destination based on a new proposed metric, and thereafter selects mini‐paths, which connect pairs of intermediate nodes along the primary path. The primary path and mini‐paths are concurrently deployed, as multiple copies of packets are routed through. This technique compensates for possible outage at intermediate wireless nodes or their corresponding wireless links along the primary path. Routing along mini‐paths is performed in such a way that redundant copies do not cause an excessive congestion on the network. The effectiveness of the proposed scheme is evaluated analytically and through extensive simulations under various load conditions. The results demonstrate the superiority of the proposed multi‐path organization in terms of reliability and satisfactory achievements of the protocol in enhancing delay and throughput compared to the existing routing protocols, especially for long distances and in congested conditions. Copyright © 2010 John Wiley & Sons, Ltd.
Metal‐based nanoparticles and their toxicity assessment
Authors: Schrand Amanda M. , Rahman Mohammad F. , Hussain Saber M. , Schlager John J. , Smith David A. , Syed Ali F.
Published: August 2010

Nanoparticles (NPs) can potentially cause adverse effects on organ, tissue, cellular, subcellular, and protein levels due to their unusual physicochemical properties (e.g., small size, high surface area to volume ratio, chemical composition, crystallinity, electronic properties, surface structure reactivity and functional groups, inorganic or organic coatings, solubility, shape, and aggregation behavior). Metal NPs, in particular, have received increasing interest due to their widespread medical, consumer, industrial, and military applications. However, as particle size decreases, some metal‐based NPs are showing increased toxicity, even if the same material is relatively inert in its bulk form (e.g., Ag, Au, and Cu). NPs also interact with proteins and enzymes within mammalian cells and they can interfere with the antioxidant defense mechanism leading to reactive oxygen species generation, the initiation of an inflammatory response and perturbation and destruction of the mitochondria causing apoptosis or necrosis. As a result, there are many challenges to overcome before we can determine if the benefits outweigh the risks associated with NPs. WIREs Nanomed Nanobiotechnol 2010 2 544–568

This article is categorized under:

Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials
From cradle to grave: RNA biology in malaria parasites
Authors: Hughes Katie R. , Philip Nisha , Lucas Starnes G. , Taylor Sonya , Waters Andrew P.
Published: August 2010

Malaria is caused by the unicellular apicomplexan parasites of the genus Plasmodium, some of which, including the major human parasite Plasmodium falciparum, have extreme genome compositions (A/T content > 80%). In this overview of RNA production, roles and degradation, we show that despite their unusual genome composition these parasites generally exhibit the standard eukaryotic features of these processes. Thus genes are monocistronic and transcribed by RNA polymerases that conform to the general categories of I, II, and III. Plasmodium spp. are unusual in that they possess structurally distinct rRNA genes that are expressed at different points in the complicated life cycle of the parasite. Transcription in blood stage asexual parasites follows a cascade consistent with a dependency upon plant‐like apetala 2 (AP2) DNA‐binding proteins. mRNA is transported to, translated and degraded in the cytoplasm and the transcription pattern is largely inflexible and responsive to temperature and glucose but not drugs. Furthermore, although Plasmodium spp. undertake controlled repression of mRNA species at a number of points in their life cycle only one mechanism, employed by female gametocytes (gamete precursor cells), is clear; it resembles that of metazoan female gametes, consisting of a complex of repression‐associated proteins in an architecture formed with the mRNA 5′ cap and dependent on U‐rich untranslated region (UTR) elements. Extensive antisense transcription has been documented resulting in the production of both short and long transcripts of generally unknown functional significance. This review attempts to summarize what is currently known about the biology of Plasmodium RNA. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Translation > Translation Regulation

RNA in Disease and Development > RNA in Disease

RNA in Disease and Development > RNA in Development
HITS‐CLIP: panoramic views of protein–RNA regulation in living cells
Authors: Darnell Robert B.
Published: August 2010

The study of gene regulation in cells has recently begun to shift from a period dominated by the study of transcription factor‐DNA interactions to a new focus on RNA regulation. This was sparked by the still‐emerging recognition of the central role for RNA in cellular complexity emanating from the RNA World hypothesis, and has been facilitated by technologic advances, in particular high throughput RNA sequencing and crosslinking methods (RNA‐Seq, CLIP, and HITS‐CLIP). This study will place these advances in context, and, focusing on CLIP, will explain the method, what it can be used for, and how to approach using it. Examples of the successes, limitations, and future of the technique will be discussed. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

RNA Methods > RNA Analyses In Vitro and In Silico

RNA Interactions with Proteins and Other Molecules > RNA–Protein Complexes

Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs

RNA Methods > RNA Analyses in Cells
Signaling pathways in early cardiac development
Authors: Liu Wenrui , Foley Ann C.
Published: August 2010

Cardiomyocyte differentiation is a complex multistep process requiring the proper temporal and spatial integration of multiple signaling pathways. Previous embryological and genetic studies have identified a number of signaling pathways that are critical to mediate the initial formation of the mesoderm and its allocation to the cardiomyocyte lineage. It has become clear that some of these signaling networks work autonomously, in differentiating myocardial cells whereas others work non‐autonomously, in neighboring tissues, to regulate cardiac differentiation indirectly. Here, we provide an overview of three signaling networks that mediate cardiomyocyte specification and review recent insights into their specific roles in heart development. In addition, we demonstrate how systems level, ‘omic approaches’ and other high‐throughput techniques such as small molecules screens are beginning to impact our understanding of cardiomyocyte specification and, to identify novel signaling pathways involved in this process. In particular, it now seems clear that at least one chemokine receptor CXCR4 is an important marker for cardiomyocyte progenitors and may play a functional role in their differentiation. Finally, we discuss some gaps in our current understanding of early lineage selection that could be addressed by various types of omic analysis. WIREs Syst Biol Med 2011 3 191–205 DOI: 10.1002/wsbm.112

This article is categorized under:

Developmental Biology > Developmental Processes in Health and Disease
Survival After Pancreaticoduodenectomy for Ampullary Cancer is not Affected by Age
Authors: Yeh Chi‐Chuan , Jeng Yung‐Ming , Ho Cheng‐Maw , Hu Rey‐Heng , Chang Hsiu‐Pi , Tien Yu‐Wen
Published: August 2010

Background

Although pancreaticoduodenectomy (PD) provides the best chance of survival for elderly patients with ampullary carcinoma, it is associated with considerable surgical risk. The aim of the present study was to compare the benefits and risks of pancreaticoduodenectomy as a treatment of ampullary carcinoma between young and elderly patients.

Patients and methods

We retrospectively reviewed the medical records of 171 consecutive patients treated at our hospital. Comparison of the biological aggressiveness of ampullary cancer between old and younger patients was also performed by immunohistochemical study of several prognostic biological markers, including MUC1, MUC2, CK17, and CDX2.

Results

For patients in whom ampullary carcinoma was presumed resectable preoperatively, actuarial survival was significantly poorer in 55 elderly patients because 9 of them did not have PD (the other 46 had PD) than in 101 younger patients (all had PD). Multivariate analysis indicated that PD was the only independent prognostic factor; age was not. There were no significant differences in MUC1, CK17, MUC2, and CDX2 immunohistochemical staining of ampullary carcinomas between elderly and young patients. In spite of increased co‐morbidities, PD could be performed as safely in elderly patients as in young patients. After PD, the actuarial survivalwas similar between old and young patients.

Conclusions

Our data support the conclusion that ampullary cancers in elderly patients should be treated as aggressively as in younger patients.
Musculoskeletal Sonopathology and Ultrasound-Guided Regional Anesthesia
Authors: Macfarlane Alan J. R. , Sites Brian D. , Sites Vincent R. , Naraghi Ali M. , Chan Vincent W. S. , Singh Mandeep , Antonakakis John G. , Brull Richard
Published: August 2010

The use of real-time ultrasound guidance has revolutionized the practice of regional anesthesia. Ultrasound is rapidly becoming the technique of choice for nerve blockade due to increased success rates, faster onset, and potentially improved safety. In the course of ultrasound-guided regional anesthesia, unexpected pathology may be encountered. Such anomalous or pathological findings may alter the choice of nerve block and occasionally affect surgical management. This case series presents a variety of musculoskeletal conditions that may be encountered during ultrasound-guided regional anesthesia practice.