bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of pneumatic melt spinning processes
Authors: Jarecki Leszek , Blonski Slawomir , Blim Anna , Zachara Andrzej
Published: March 2012

Computer simulation of the pneumatic processes of fiber formation from the polymer melts is discussed. The dynamics of air‐drawing of thin polymer streams in supersonic air jets formed in the Laval nozzle is presented versus the melt blowing process. In the Laval nozzle process, the air flow takes place with high Reynolds number and the k–ω model is used which considers kinetic energy of the air flow and the specific dissipation rate of the kinetic energy. For melt blowing, the air fields are simulated with the use of the k–ε turbulent model. The air velocity, temperature, and pressure distributions along the centerline of the air jets are considered in the modeling of both pneumatic processes. The air fields are predetermined at the absence of the polymer streams for several air compression values in the Laval nozzle inlet and several initial air velocities in the melt blowing process. Each polymer stream in a usual configuration of a single row of the filaments in the process is considered as non‐interacting aerodynamically with other streams, and the air jet is assumed to be undisturbed by the polymer streams. Air‐drawing of the polymer filaments is simulated as controlled by the distribution of air velocity, temperature, and pressure on the air jet centerline with the use of a stationary model of melt spinning in a single‐, thin‐filament approximation. Effects of non‐linear viscoelasticity of the polymer melt subjected to fast uniaxial elongation are accounted for in the modeling. Strong influence of the air jet velocity, the melt viscosity which controls response of the polymer melt on the air‐drawing forces, and the die‐to‐collector distance has been predicted. Influence of initial air temperature, geometry of the air die, initial velocity and temperature of the melt, extrusion orifice diameter can be also predicted from the model. The example computations concern air‐drawing of isotactic polypropylene with the use of the Laval nozzle are compared with the predictions for the melt blowing process. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Modeling stiffness of nanolayered silicate‐modified polyamide 6 via FEM micromechanical modeling and analytical composite models
Authors: Huang Jing , Geier Simon , Schmauder Siegfried , Weber Ulrich
Published: March 2012

In this work, numerical and analytical models are chosen to study reinforcement effect of nanolayered silicate modified polyamide 6 (PA 6) composites at ambient temperature. A numerical self‐consistent unit cell model in conjunction with finite element method is applied to predict the stiffness of this polymer nanocomposite, which has been successfully applied for simulating mechanical behavior of metal matrix composites. In this work, a rectangular inclusion (layered silicate) is surrounded by PA 6 polymer matrix, which is again embedded in the PA 6/layered silicate nanocomposite. The stiffness of the composite is determined iteratively in a self‐consistent manner. For comparison, two analytical composite models (Halpin–Tsai model and Tangdon–Weng model) are implemented to evaluate the stiffness of this nanocomposite via calculations performed within MATLAB. In the modeling volume fraction, aspect ratio, exfoliation and orientation of the nanolayered silicate are taken into account. It is demonstrated that the numerical approach using the self‐consistent embedded cell model coincides well with experimental results of the stiffness of the composite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Nucleated crystallization of isotactic polypropylene in multilayered sandwich nanocomposites with gold particles
Authors: Slouf Miroslav , Sikora Antonin , Pavlova Ewa , Vlkova Helena , Baldrian Josef , Base Tomas , Piorkowska Ewa
Published: March 2012

Nucleation of isotactic polypropylene (PP) crystallization by gold particles with various sizes and shapes was studied. The morphology of gold particles ranged from microcrystals with well‐developed crystal facets (AuMC) to vacuum‐sputtered 5 nm gold nanoparticles (AuNP), 30 nm gold nanoislands (AuNI), and compact gold nanolayer (AuNL). To minimize agglomeration of Au particles in molten PP, the nucleated crystallization was studied by means of the improved sandwich method, which consisted in the controlled deposition of a homogeneous nucleant layer between ∼ 100 μm PP films, followed by the careful thermal treatment and the evaluation of the nucleation activity by three independent methods: polarized‐light microscopy, two‐dimensional wide‐angle X‐ray scattering, and differential scanning calorimetry. It was demonstrated that the nucleating activity of gold strongly depended on its morphology: The nucleation effect of microcrystalline AuMC resulted in a transcrystallization comparable to that caused by a strong commercial α‐nucleant (Hyperform HPN‐68), whereas the effect of vacuum‐sputtered layers of nanocrystalline AuNL, AuNI, and AuNP was extremely weak. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis, Characterization, and Energetic Properties of Salts of the 1‐Cyanomethyl‐1,1‐dimethylhydrazinium Cation
Authors: Miró Sabaté Carles , Delalu Henri , Jeanneau Erwann
Published: March 2012

1,1‐Dimethylhydrazine can be readily alkylated with bromoacetonitrile to form 1‐cyanomethyl‐1,1‐dimethylhydrazinium bromide ([(CH3)2N(CH2CN)NH2]Br, 1). The metathesis reaction of compound 1 led to the formation of a new family of energetic salts based on the [(CH3)2N(CH2CN)NH2]+ cation and nitrate (2), perchlorate (3), azide (4), 5‐aminotetrazolate ([H2N‐CN4]−, 5), 5,5′‐azobistetrazolate ([N4C‐NN‐CN4]2−, 7), and picrate (8) anions. The new materials were characterized by elemental analysis, mass spectrometry, and (multinuclear) NMR and vibrational (infrared and Raman) spectroscopies. Additionally, the molecular structure of the [(CH3)2N(CH2CN)NH2]+ cation in compounds 1, 3, and 8 and that of sodium 5,5′‐azobistetrazolate octahydrate (NaZT⋅8 H2O) were solved by X‐ray diffraction techniques. The hydrogen‐bonding networks found in the structure of salts 1, 3, 8, and NaZT⋅8 H2O are described using graph‐set analysis. The melting and decomposition points of the new compounds were determined by differential scanning calorimetry, and insight into their sensitivity towards impact, friction, and electrostatics was gained by submitting the materials to standard tests. Furthermore, we estimated some performance parameters of interest and predicted the decomposition gases formed upon decomposition of salts 2, 3, 4, 5, 6, 7, 8 and of mixtures with an oxidizer. The interesting thermal, sensitivity, and performance properties of some of the compounds described in this work make them attractive towards a prospective energetic application.
Tragverhalten von hohen Stahlbetontürmen für Aufwindkraftwerke
Authors: Goldack Arndt
Published: March 2012

Aufwindkraftwerke sind solarthermische Kraftwerke zur Gewinnung erneuerbarer Energie aus der direkten und indirekten Sonneneinstrahlung. Für diese Kraftwerke sind Türme mit Höhen bis zu 1000 m und mehr erforderlich, die als freistehende Stahlbetonröhren geplant sind. Diese Stahlbetonröhren werden mit mehreren Aussteifungen wie z. B. Speichenrädern, die über die Höhe verteilt angeordnet sind, ausgesteift, um die Membranschnittgrößen aus Wind möglichst gering zu halten. Das Tragverhalten dieser mehrfach ausgesteiften Türme besteht aus einem stabartigen über die gesamte Turmröhre und einem schalenartigen Tragverhalten in den Segmenten zwischen den Aussteifungen. Die Traglasten verschiedener 1000 m hoher Türme wurden mit geometrisch und physikalisch nichtlinearen FEM‐Berechnungen ermittelt. Dabei zeigt sich, dass die Rissbildung das Tragverhalten maßgeblich beeinflusst. In Verbindung mit dem Flankensog führt diese zu einer typischen sichelförmigen Ovalisierung der Segmente zwischen den Aussteifungen, die auf das schalenartige Tragverhalten zurückzuführen ist. Es zeigte sich, dass das schalenartige Tragverhalten im Bereich der sichelförmigen Ovalisierung infolge Biegung mit Längsdruck maßgebend ist. Vergleichsrechnungen am obersten Turmsegment zeigen wiederum dieses typische Tragverhalten.

Load bearing of high rise tubes for solar updraft towers

Solar updraft power plants are solar thermal power plants for producing renewable electric energy from direct and indirect solar radiation. These power plants demand for high rise tower tubes with heights up to 1000 m and more, which are planned as cantilevering tubes out of structural concrete. These tower tubes are provided with several stiffeners such as spoke wheels distributed over the height to keep the membrane forces due to wind at a minimum. The load bearing of these multi‐stiffened towers consists of a cantilever‐like and a shell‐like in the segments between two stiffeners. The ultimate loads of several 1000 m high tower tubes were investigated by geometrical and physical non‐linear FEM calculations. Cracking of the concrete has a reasonable impact on the ultimate limit state and results together with the flank suction in a typical sickle‐like ovalling between the luv and the flank suction. The ultimate limit state of these towers is governed by the shell‐like behavior in the sickle‐like deformation with bending and longitudinal force. Additional non‐linear FEM calculations of the topmost segment of the tower show the same deformation and failure mechanism.
Solare Aufwindkraftwerke: Ein Beitrag der Bautechnik zur nachhaltigen und wirtschaftlichen Energieerzeugung
Authors: Harte Reinhard , Höffer Rüdiger , Krätzig Wilfried B. , Mark Peter , Niemann Hans‐Jürgen
Published: March 2012

Solare Aufwindkraftwerke stellen eine Technologie zur Erzeugung solar‐basierter elektrischer Energie in den Wüsten unserer Erde dar, die verschiedene Defizite bisheriger Konzepte überwindet. Weltweit sind derartige Kraftwerksprojekte in der Vorplanung. Der vorliegende Beitrag beginnt mit der Skizzierung des Arbeitsprinzips solarer Aufwindkraftwerke. Es folgen klimatologische und wind‐technologische Planungsvoraussetzungen, wobei die Windlastermittlung im Grenzschicht‐Windkanal näher begründet wird. Sodann wird der zentrale Solarkamin behandelt, eine dünne, ringversteifte Stahlbetonschale extremer Höhe, die größte bautechnische Herausforderung dieses Kraftwerkstyps. Weiter folgt die Erläuterung grundlegender bautechnischer Anforderungen an den Solarkollektor, der die größte jemals überglaste Fläche darstellt, sowie der Windeinwirkungen auf die Verglasung und die Tragkonstruktion. Einen wichtigen Aspekt bilden Anforderungen an die Dauerhaftigkeit der eingesetzten Baustoffe für eine mindestens 100‐jährige Nutzung des Turms in einem extremen Wüstenklima. Der Artikel endet mit Kostenschätzungen für den produzierten Strom und einem Technologieausblick.

Solar updraft power plants: A structural engineering contribution for sustainable and economic power generation

Solar updraft power technology serves to generate electricity in the world‐wide deserts, overcoming several deficits of present renewable energy technologies. In several suited countries such power plant projects are in preparation. The present contribution starts with an explanation of the working principle of solar updraft power plants, followed by their climatic and wind‐technologic design assumptions, terminated by the wind‐load determination in boundary layer wind‐tunnels. Then the central solar chimney – the power tower – will be treated, a thin ring‐stiffened RC shell of extreme height forming the utmost structural challenge of such power plants. This part is followed by an explanation of technical requirements for the collector construction, which represents by far the largest glass‐covered area ever built, and of the wind loading at the glazing and the supporting structure. Further important aspects are formed by the durability requirements of the applied construction materials for at least 100 years of service‐duration of the tower in extreme desert climates. The paper closes with cost estimates for the generated electric power and with a technology outlook.
Kollektorentwicklung für solare Parabolrinnenkraftwerke
Authors: Schiel Wolfgang
Published: March 2012

In den letzten Jahren wurden mehrere große solarthermische Kraftwerke in Spanien und Nordafrika gebaut und in Betrieb genommen. Bis Ende 2013 werden allein in Spanien solarthermische Kraftwerke mit einer Leistung von insgesamt ca. 2,5 GW am Netz angeschlossen sein. Die meisten dieser Anlagen sind sogenannte Parabolrinnenkraftwerke, die zurzeit am weitesten fortgeschrittene solarthermische Technologie. Diese Kraftwerke bestehen aus großen Kollektorfeldern mit hunderttausenden Quadratmetern Kollektorflächen, die die erforderliche Wärme für den Betrieb eines konventionellen Kraftwerksblocks bereitstellen. Die Kosten dieser solarthermischen Technologie werden im Wesentlichen durch die Kosten des Kollektorfeldes bestimmt. Um in Zukunft mit fossilen Kraftwerken vergleichbare Stromerzeugungskosten zu erzielen, sind weitere Entwicklungsarbeiten der solarspezifischen Komponenten im Hinblick auf Kostensenkung und Effizienzsteigerung erforderlich, insbesondere beim Solarkollektor.

Collector dvelopment for solar parabolic trough power plants

In the last years several solar thermal power plants were constructed and successfully put into operation in Spain and North Africa. By the end of 2013, a total of 2, 5 GW solar thermal power plants will be in operation in Spain alone. Most of these plants are parabolic trough power plants, which is currently the most highly developed solar thermal technology. These power plants consist of a large solar collector field with hundreds of thousands of m2 collector areas, which generate the required warmth for the operation of a conventional power block. The costs of this technology are primarily determined by the costs of the collector field. In order to achieve electricity generation costs that are competitive to fossil power plants, further developments of the solar components with regard to cost reduction and increased efficiency are necessary, especially for the solar collector.
Variable electric fields for high throughput electroporation protocol design in curvilinear coordinates
Authors: Fernand Francois , Rubinsky Liel , Golberg Alex , Rubinsky Boris
Published: March 2012

The mathematical solution to the electric field equation in cylindrical coordinates, has suggested to us a new experimental methodology and device for reducing experimental effort in designing electroporation protocols. Using a new cylindrical electroporation system, we show, with an Escherichia coli cell model, how key electroporation parameters emerge precisely from single experiments rather than through interpolation from numerous experiments in the conventional Cartesian electroporation system. Biotechnol. Bioeng. 2012; 109:2168–2171. © 2012 Wiley Periodicals, Inc.
Influence of Vanadium or Cobalt Oxides on the CO Oxidation Behavior of Au/MOx/CeO2–Al2O3 Systems
Authors: Reina Tomás Ramírez , Moreno Andrea Álvarez , Ivanova Svetlana , Odriozola José Antonio , Centeno Miguel Angel
Published: March 2012

A series of V2O5‐ and Co3O4‐modified ceria/alumina supports and their corresponding gold catalysts were synthesized and their catalytic activities evaluated in the CO oxidation reaction. V2O5‐doped solids demonstrated a poor capacity to abate CO, even lower than that of the original ceria/alumina support, owing to the formation of CeVO4. XRD, Raman spectroscopy, and H2‐temperature programmed reduction studies confirmed the presence of this stoichiometric compound, in which cerium was present as Ce3+ and its redox properties were avoided. Co3O4‐doped supports showed a high activity in CO oxidation at subambient temperatures. The vanadium oxide‐doped gold catalysts were not efficient because of gold particle agglomeration and CeVO4 formation. However, the gold–cobalt oxide–ceria/alumina catalysts demonstrated a high capacity to abate CO at and below room temperature. Total conversion was achieved at −70 °C. The calculated apparent activation energy values revealed a theoretical optimum loading of a half‐monolayer.
On the Lifetime of the Transients (NP)(CH3)n (NP=Ag0, Au0, TiO2 Nanoparticles) Formed in the Reactions Between Methyl Radicals and Nanoparticles Suspended in Aqueous Solutions
Authors: Bar‐Ziv Ronen , Zilbermann Israel , Oster‐Golberg Olga , Zidki Tomer , Yardeni Guy , Cohen Haim , Meyerstein Dan
Published: March 2012

Methyl radicals react in fast reactions, with rate constants k>1×108 M−1 s−1, with Au0, Ag0 and TiO2 nanoparticles (NPs) dispersed in aqueous solutions to form intermediates, (NP)(CH3)n, in which the methyl groups are covalently bound to the NPs. These intermediates decompose to form ethane. As n≥2 is required for the formation of C2H6, the minimal lifetime (τ) of the methyls bound to the NPs, (NP)CH3, can be estimated from the rate of production of the CH3. radicals and the NPs concentration. The results obtained in this study, using a very low dose rate γ‐source for NP=Ag0, Au0, and TiO2 point out that τ of these intermediates is surprisingly long, for example, ≥8 and ≥188 sec for silver and gold, respectively. These data point out that the NPC bond dissociation energies are ≥70 kJ mol−1. Under low rates of production of CH3., that is, when the rate of formation of ethane is very low, other reactions may occur, consequently the mechanism proposed is “broken”. This is observed in the present study only for TiO2 NPs. These results have to be considered whenever alkyl radicals are formed near surfaces. Furthermore, the results point out that the rate of reaction of methyl radicals with (NP)(CH3)n depends on n, that is, the number of methyl radicals bound to the NPs affect the properties of the NPs.
ChemInform Abstract: Chemistry and Physics of a Single Atomic Layer: Strategies and Challenges for Functionalization of Graphene and Graphene‐Based Materials
Authors: Yan Liang , Zheng Yue Bing , Zhao Feng , Li Shoujian , Gao Xingfa , Xu Bingqian , Weiss Paul S. , Zhao Yuliang
Published: March 2012

Review: 315 refs.
Integration of Organic Fluorophores in the Surface of Polymer‐Coated Colloidal Nanoparticles for Sensing the Local Polarity of the Environment
Authors: Amin Faheem , Yushchenko Dmytro A. , Montenegro Jose M. , Parak Wolfgang J.
Published: March 2012

Inorganic hydrophobically capped NPs such as quantum dots, superparamagnetic iron oxide, or gold nanoparticles can be modified to make them water‐soluble by their embedding in an amphiphilic polymer shell. This polymer shell can be prefunctionalized by the integration of organic fluorophores, which allows the observation of the nanoparticles with fluorescence based techniques. The fluorophore could be either located more in the hydrophobic part of the inner polymer shell, or on the hydrophilic surface pointing towards solution. Herein we prepared gold nanoparticles decorated with the organic fluorophore FE, 4′‐N,N‐diethylamino‐3‐hydroxyflavone (FE), which possesses fluorescence sensitive to the polarity and hydrogen‐bonding properties of the surrounding local environment. Based on the response of FE in the polymer shell to isopropanol, and CTAB compared to the response of free FE we conclude that the FE fluorophore is situated within the inner polymer shell. Nevertheless the fluorophore in the polymer shell can still sense polarity changes in solution.
Immobilised Lipase on Structured Supports Containing Covalently Attached Ionic Liquids for the Continuous Synthesis of Biodiesel in scCO2
Authors: Lozano Pedro , García‐Verdugo Eduardo , Bernal Juana M. , Izquierdo Diana F. , Burguete M. Isabel , Sánchez‐Gómez Gregorio , Luis Santiago V.
Published: March 2012

Different nanostructured supports, based on 1‐decyl‐2‐methyimidazolium cations covalently attached to a polystyrene divinylbenzene porous matrix, were used as carriers to immobilise Candida antarctica lipase B. The suitability of these immobilised lipase derivatives for the synthesis of biodiesel (methyl oleate) by the methanolysis of triolein has been tested in both tert‐butanol and supercritical (sc)CO2 (18 MPa, 45 °C) as reaction media. The use of modified supports with low ionic‐liquid loading covalently attached to the main polymeric backbone chains provide structured materials that led to the best biodiesel yields (up to 95 %) and operational stability (85 % biodiesel yield after 45 cycles of 8–4 h) in scCO2 (45 °C, 18 MPa). The presence of tert‐butanol as an inert cosolvent in the scCO2 phase at the same concentration as triolein was key to avoid poisoning the biocatalyst through the blockage of its active sites by the polar byproduct (glycerol) produced in the biodiesel synthesis.
Performance analysis of time division broadcast protocol with incremental relaying and symmetric users
Authors: Xu Kun , Gao Yuanyuan , Yi Xiaoxin , Zang Guozhen , Sha Nan
Published: March 2012

This paper investigates two‐way relaying with direct link transmission. We propose to combine incremental relaying (IR) with the time division broadcast protocol (TDBC) to form a new scheme, termed TDBC‐IR, to increase the spectral efficiency of TDBC. Assuming half‐duplex decode‐and‐forward relaying, the performance of three protocols, that is, TDBC, TDBC‐IR, and physical‐layer network coding (PNC), are studied and compared, in terms of outage probability, expected rate (ER), and diversity‐multiplexing tradeoff. First, we reveal that the outage probability performance of TDBC‐IR is the same as that of TDBC and better than that of PNC. Second, we compare the ER and diversity‐multiplexing tradeoff performance of the three protocols based on the derived outage probability. The numerical results reveal that (1) the ER of TDBC‐IR is greater than that of TDBC and PNC in the whole signal‐to‐noise ratio (SNR) region, that is TDBC‐IR has improved spectral efficiency performance; (2) the ER performance of TDBC is better than PNC in the low SNR region but worse in the high SNR region; (3) the maximum achievable diversity order of TDBC‐IR and TDBC are both two whereas that of PNC is one; (4) the maximum achievable multiplexing gain of TDBC‐IR is one, which is better than TDBC (its maximum achievable is 2/3) and achieves the maximum of PNC (its maximum achievable is one). Copyright © 2012 John Wiley & Sons, Ltd.
Commentary on: ‘Universal school‐based prevention programmes for alcohol misuse in young people’
Authors: Newton Nicola C. , Teesson Maree
Published: March 2012

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Foxcroft DR, Tsertsvadze A. Universal school‐based prevention programmes for alcohol misuse in young people. Cochrane Database of Systematic Reviews 2011, Issue 5. Art. No.: CD009113. DOI: 10.1002/14651858.CD009113.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2012 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Commentary on: ‘Kangaroo mother care to reduce morbidity and mortality in low‐birth‐weight infants’
Authors: Warnock Fay F. , Castral Thaila
Published: March 2012

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Conde‐Agudelo A, Belizán JM, Diaz‐Rossello J. Kangaroo mother care to reduce morbidity and mortality in low‐birth‐weight infants. Cochrane Database of Systematic Reviews 2011, Issue 3. Art. No.: CD002771. DOI: 10.1002/14651858.CD002771.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2012 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Untersuchungen zur hydraulischen Stützung mit Polymerlösungen
Authors: Lesemann Henning , Vogt Norbert
Published: March 2012

Polymere Lösungen stellen eine technisch und wirtschaftlich interessante Alternative zu den bislang üblicherweise verwendeten Bentonitsuspensionen für die hydraulische Stützung von Bohrlöchern und Schlitzen dar und werden im Ausland seit Jahren zunehmend eingesetzt. Die in Frage kommenden Polymerlösungen weisen im Gegensatz zu Bentonitsuspensionen praktisch keine Fließgrenze auf, weshalb sich das Eindring‐ und Stützverhalten wesentlich unterscheidet und die bekannten Nachweise der Schlitzstabilität nicht anwendbar sind. Durch ein Forschungsvorhaben am Zentrum Geotechnik der Technischen Universität München sollten die Kenntnisse über das Verfahren und dessen Anwendbarkeit erweitert und dokumentiert werden, um die Planung und den sicheren und verantwortungsvollen Einsatz in der Praxis zu erleichtern. Hierzu wurden die theoretischen Grundlagen zur Strömung solcher nicht‐newtonscher Fluide im Lockergestein aufbereitet und Möglichkeiten der Modellierung diskutiert. In Laborversuchen wurden das Strömungsverhalten der Lösungen und die Parameterbestimmung für die Modelle untersucht. In Feldversuchen wurden fünf Bohrpfähle polymergestützt und ein Vergleichspfahl bentonitgestützt hergestellt und dabei auch weitere baupraktische Fragestellungen untersucht. Außerdem wurden Hinweise zum Nachweisverfahren gegeben und die Umweltverträglichkeit des Verfahrens betrachtet.

Investigations into hydraulic support using polymeric solutions Polymer solutions turn out to be a technically and economically promising alternative to the so far commonly used bentonite suspensions for the hydraulic support of boreholes or diaphragm wall trenches and have been used increasingly abroad. As a consequence of the almost non‐existent yield strengths of the applicable polymer solutions, their flow and support characteristics differ considerably from those of bentonite suspensions and established stability analyses cannot be adopted. A research project at the Zentrum Geotechnik, Technische Universität München, was carried out to improve and document the knowledge of this method and its applicability. Therefore, basic principles of the flow of such non‐Newtonian fluids in soil were recapitulated and options for modelling were discussed. The flow behaviour of the polymeric solutions and the determination of model parameters were studied in laboratory tests. In field tests, five bored piles were completed under polymeric support and one reference pile under bentonite support. In the course of these tests, further issues of relevance for construction practice were investigated. Finally, details of the stability analyses were specified and the environmental compatibility of the construction method was examined.
Stand der europäischen und deutschen geotechnischen Normen
Authors: Schuppener Bernd , Eitner Volker , Linder Wolf‐Rüdiger , Richter Thomas , Ruppert Franz‐Reinhard , Zurborg Jens
Published: March 2012

Im Juli 2012 sollen die Eurocodes bauaufsichtlich eingeführt werden. Das ist Anlass, die wesentlichen Neuerungen in den beiden Teilen des Eurocodes 7: Entwurf, Bemessung und Berechnung in der Geotechnik – Teil 1: Allgemeine Regeln (EC 7‐1) und Teil 2: Erkundung und Untersuchung des Baugrunds (EC7‐2) sowie in den beiden Ergänzungsnormen DIN 1054:2010‐12 und DIN 4020:2010‐12 vorzustellen. Da die Einführung des EC 7‐1 eine Reihe von Anpassungen bei den geotechnischen Berechnungsnormen erforderlich machte und darüber hinaus schon seit Jahren die Herstellungsnormen des Grundbaus auf europäischer Ebene weiterentwickelt werden, wird ebenfalls über den Stand dieser Normen und die weitere Normungsarbeit berichtet.

State of the German and European geotechnical standards In July 2012 the Eurocodes will officially be implemented by the German authorities. For this reason the most important innovations of both parts of Eurocode 7: Geotechnical design – Part 1: General rules (EC 7‐1) and Part 2: Ground investigation and testing (EC7‐2) will be presented as well as the supplementary rules of DIN 1054:2010‐12 und DIN 4020:2010‐12. The implementation of EC 7‐1 necessitated some adjustments in the standards for geotechnical calculations and as the standards for execution of special geotechnical works have been developed very significantly in the past years they are also included in the report.
Healthcare financing in Syria: satisfaction with the current system and the role of national health insurance—a qualitative study of householders' views
Authors: Mershed Mania , Busse Reinhard , van Ginneken Ewout
Published: March 2012

This study aims to identify the satisfaction with the current public health system and health benefit schemes, examine willingness to participate in national health insurance and review expectations and preferences of national health insurance. To this end, qualitative semi‐structured interviews were carried out with 19 Syrian householders. Our results show that a need for health reform exists and that Syrian people are willing to support a national health insurance scheme if some key issues are properly addressed. Funding of the scheme is a major concern and should take into account the ability to pay and help the poor. In addition, waiting times should be shortened and sufficient coverage guaranteed. On the whole, the people would support a national health insurance with national pooling and purchasing under a public set‐up, but important concerns of such a system regarding corruption and inefficiency were voiced too. Installing a quasi non‐governmental organisation as manager of the insurance system under the stewardship of the Ministry of Health could provide a compromise acceptable to the people. Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis of Functionalized Polytriazoles via One‐Pot Sequential Copper‐Catalyzed Azide–Alkyne [3+2] Cycloaddition and Atom Transfer Radical Addition (ATRA)
Authors: Ricardo Carolynne L. , Pintauer Tomislav
Published: March 2012

As a continuing effort of expanding the scope of catalyst regeneration in the presence of environmentally benign reducing agents, one‐pot sequential azide–alkyne [3+2] cycloaddition and atom transfer radical addition (ATRA) reactions were performed via in situ reduction of copper(II) by ascorbic acid. The formation of functionalized triazoles was achieved utilizing a ligand‐free catalytic system for the cycloaddition between tripropargylamine and vinylbenzyl azide and subsequent addition of tris(2‐pyridyl)methylamine (TPMA) ligand in the ATRA step. With this strategy, reactions with carbon tetrachloride and carbon tetrabromide proceeded efficiently providing the desired triazoles in nearly quantitative yields (>90 %) using 10 mol % of copper. Sequential azide–alkyne [3+2] cycloaddition and ATRA reactions were also extended to less active alkyl halides such as methyl trichloroacetate, methyl dichloroacetate and dichloroacetonitrile. The corresponding products were obtained in modest yields (50–80 %). The presented methodology enables efficient synthesis of functionalized polytriazoles, which could have a potential use as chelating agents for a variety of transition metals.
Internet Adoption by Travel Agents: a Case of Egypt
Authors: Abou‐Shouk Mohamed , Lim Wai Mun , Megicks Phil
Published: March 2012

Current collaborative and rapid developments in tourism and information and communication technologies (ICTs) make it difficult to imagine that tourism existed before ICTs. Communication technology is one main reason for the existence of the Internet. Travel agents (TAs) are among service providers whom their Internet adoption could be the best marketing device for their business and a tool for their competitive advantages. The study explores the Internet adoption of the Egyptian TAs, patterns of usage and perceived benefits and barriers of e‐commerce adoption. It is found that the majority of TAs use the Internet to provide TA's information, find out about customers and competitors. Sales and revenue growth, increasing competitive advantages and marketing activities are the agents’ perceived benefits of adopting e‐commerce. Limited resources, unskilled labour, lack of readiness of public infrastructure and customers are among the main obstacles for not adopting the Internet technologies. Copyright © 2012 John Wiley & Sons, Ltd.
NMR spectroscopic investigation of inclusion complexes between cyclodextrins and the neurotoxin tetramethylenedisulfotetramine
Authors: Mayer Brian P. , Albo Rebecca L. F. , Hok Saphon , Valdez Carlos A.
Published: March 2012

The binding stoichiometry, strength and structure of inclusion complexes formed between the neurotoxin tetramethylenedisulfotetramine (TETS) and both native and modified cyclodextrins (CyDs) were investigated using nuclear magnetic resonance (NMR) spectroscopy. Of all six examined cases, native β‐cyclodextrin (β‐CyD) and its chemically modified counterpart heptakis‐(2,3,6‐tris‐(2‐hydroxypropyl))‐β‐cyclodextrin (2HP‐β‐CyD) were found to associate most strongly with TETS as reflected in the magnitude of their binding constants (K = 537 ± 26 M−1 for β‐CyD and K = 514 ± 49 M−1 for 2HP‐β‐CyD). Two‐dimensional rotating‐frame Overhauser effect spectroscopy NMR experiments confirm close proximity of the TETS molecule to both β‐CyD and 2HP‐β‐CyD as intermolecular, through‐space interactions between the H3 and H5 protons located in the interior of the CyD cavity and the methylene protons of TETS were identified. Copyright © 2012 John Wiley & Sons, Ltd.
Measurement of 129Xe gas apparent diffusion coefficient anisotropy in an elastase‐instilled rat model of emphysema
Authors: Boudreau Mathieu , Xu Xiaojun , Santyr Giles E.
Published: March 2012

Hyperpolarized noble gas (3He and 129Xe) apparent diffusion coefficient (ADC) measurements have shown remarkable sensitivity to microstructural (i.e., alveolar) changes in the lung, particularly emphysema. The ADC of hyperpolarized noble gases depends strongly on the diffusion time (Δ), and 3He ADC has been shown to be anisotropic for Δ ranging from a few milliseconds down to a few hundred microseconds. In this study, the anisotropic nature of 129Xe diffusion and its dependence on Δ were investigated both numerically, in a budded cylinder model, and in vivo, in an elastase‐instilled rat model of emphysema. Whole lung longitudinal ADC (DL) and transverse ADC (DT) were measured for Δ = 6, 50, and 100 ms at 73.5 mT, and correlated with measurements of the mean linear intercept (Lm) obtained from lung histology. A significant increase (P = 0.0021) in DT was measured for Δ = 6 ms between the sham (0.0021 ± 0.0005 cm2/s) and elastase‐instilled (0.005 ± 0.001 cm2/s) cohorts, and a strong correlation was measured between DT (Δ = 6 ms) and Lm, with a Pearson's correlation coefficient of 0.90. This study confirms that 129Xe DT increases correlate with alveolar space enlargement due to elastase instillation in rats. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Prävention und Therapie von entzündlichen Magen‐/Darm‐Erkrankungen
Authors: Stein Jürgen , Dignaß Axel
Published: March 2012

Probiotika können bei verschiedenen Infektionen und chronischen Entzündungen des Magen‐Darm‐Traktes erfolgreich eingesetzt werden. Der folgende Artikel fasst die aktuelle Studienlage zusammen.
Synthesis and optimization of molecularly imprinted polymers for quercetin
Authors: Yu Hui , Chen Zhenbin , Fu Yu , Kang Lei , Wang Meng , Du Xueyan
Published: March 2012

Molecularly imprinted polymers (MIPs) were synthesized through solution polymerization using quercetin as the template molecule, N‐vinylpyrrolidone and acrylic acid as functional monomers, N,N′‐methylenebiacrylamide as crosslinker and the redox system L‐ascorbic acid and hydrogen peroxide as initiator in the porogen of ethanol and water. During the optimization process an interference compound, genistein (5,7,4′‐trihydroxy isoflavone), which possesses the same skeleton and functional groups as quercetin, was adopted to optimize the preparation conditions, and the separation degree of the MIP to quercetin and genistein was chosen to optimize each factor. The synthesized MIP under optimal conditions showed a specific recognition of quercetin from a mixture of quercetin and genistein. Thereafter, the structure of the MIP was comparatively characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and Brunauer–Emmett–Teller analysis using non‐imprinted molecular polymers as control. In addition, the kinetics of the adsorption process were also studied, and Scatchard analysis revealed that heterogeneous binding sites were formed in the polymers. Copyright © 2012 Society of Chemical Industry
Täglich genutzt und kaum bekannt
Authors: Ehrmann Andrea , Blachowicz Tomasz
Published: March 2012

Der Exchange Bias gehört zu den physikalischen Effekten, die trotz ihrer technologischen Relevanz kaum bekannt sind. Seine wichtigste Anwendung ist der Einsatz in Schreibleseköpfen von Festplatten. Durch ihn sind sie so empfindlich geworden, dass sie extrem kleine magnetische Domänen als Bits lesen können. Das eröffnete den Weg zu Festplatten mit Kapazitäten von vielen Gigabytes. Der Effekt entsteht durch die Kombination von ferromagnetischen mit antiferromagnetischen Materialien. Obwohl bereits 1956 entdeckt, ist er theoretisch noch nicht völlig verstanden. Auch heute bietet er der Grundlagenforschung ein reiches Feld neuer Entdeckungen. Diese könnten wiederum Eingang in neue Technologien finden.
Lorentz‐Pendel in der Glühbirne
Authors: Vollmer Michael , Möllmann Klaus‐Peter
Published: March 2012

Die Lorentz‐Kraft auf bewegte Ladungen im Magnetfeld lässt sich auf unterschiedliche Weise demonstrieren. Ein beeindruckendes Beispiel ist die wechselstromdurchflossene Wendel einer Glühlampe, die in einem zeitlich konstanten Magnetfeld schwingt. Mit einer Hochgeschwindigkeitskamera kann man diese schnelle Bewegung zeitaufgelöst darstellen.
Precipitation distributions for explicit versus parametrized convection in a large‐domain high‐resolution tropical case study
Authors: Holloway C. E. , Woolnough S. J. , Lister G. M. S.
Published: March 2012

Global climate and weather models tend to produce rainfall that is too light and too regular over the tropical ocean. This is likely because of convective parametrizations, but the problem is not well understood. Here, distributions of precipitation rates are analyzed for high‐resolution UK Met Office Unified Model simulations of a 10 day case study over a large tropical domain (∼20°S–20°N and 42°E–180°E). Simulations with 12 km grid length and parametrized convection have too many occurrences of light rain and too few of heavier rain when interpolated onto a 1° grid and compared with Tropical Rainfall Measuring Mission (TRMM) data. In fact, this version of the model appears to have a preferred scale of rainfall around 0.4 mm h−1(10 mm day−1), unlike observations of tropical rainfall. On the other hand, 4 km grid length simulations with explicit convection produce distributions much more similar to TRMM observations. The apparent preferred scale at lighter rain rates seems to be a feature of the convective parametrization rather than the coarse resolution, as demonstrated by results from 12 km simulations with explicit convection and 40 km simulations with parametrized convection. In fact, coarser resolution models with explicit convection tend to have even more heavy rain than observed. Implications for models using convective parametrizations, including interactions of heating and moistening profiles with larger scales, are discussed. One important implication is that the explicit convection 4 km model has temperature and moisture tendencies that favour transitions in the convective regime. Also, the 12 km parametrized convection model produces a more stable temperature profile at its extreme high‐precipitation range, which may reduce the chance of very heavy rainfall. Further study is needed to determine whether unrealistic precipitation distributions are due to some fundamental limitation of convective parametrizations or whether parametrizations can be improved, in order to better simulate these distributions. Copyright © 2012 Royal Meteorological Society
Investigation of the presence of endogenous prednisolone in equine urine by high‐performance liquid chromatography mass spectrometry and high‐resolution mass spectrometry
Authors: Fidani Marco , Pompa Giuseppe , Mungiguerra Francesca , Casati Alessio , Fracchiolla Maria Letizia , Arioli Francesco
Published: March 2012

RATIONALE

After the detection of low concentrations of prednisolone in racehorse urine samples collected at Italian racetracks, a study was initiated to investigate the accuracy of the analytical protocol used and the possible endogenous origin of detected prednisolone.

METHODS

Multiple reaction monitoring (MRM) MS2 acquisition with a triple quadrupole (n = 780) and full scan MS2 and MS3 (n = 180) acquisition with a linear ion trap were checked. As a further confirmation, ten urine samples were analysed by high‐resolution mass spectrometry (HRMS).

RESULTS

The study showed the difficulty of identifying prednisolone, probably due to interfering compounds with the same molecular weight (360 Da) present in the matrix. The characteristic transitions for prednisolone were identified, both in MS2 and MS3, as the ions 187 and 280; the ion 295 was also used for identification. The concentrations detected with the triple quadrupole and the linear ion trap were not statistically different. The exact mass of prednisolone formiate (the adduct acting as a molecular ion) was identified by HRMS.

CONCLUSIONS

The very high frequency of prednisolone detection in the samples (78.5%), the low concentration of this steroid and, importantly, the narrow range of the 95% confidence limits (0.97–1.05 in MS2 mode and 0.88–1.04 in MS3 mode), could represent evidence that its presence is endogenous. In the light of these results, this hypothesis seems the most probable, even if further studies are required to confirm it. Furthermore, a microbiological origin (i.e. fermentation of cortisol after sample collection) could not be disregarded. Copyright © 2012 John Wiley & Sons, Ltd.
Identification of imine or enamine drug metabolites using online hydrogen/deuterium exchange and exact mass measurements
Authors: Li Austin C. , Yu Erya , Ring Steven C. , Chovan James P.
Published: March 2012

RATIONALE

Drug metabolites that have imine or enamine partial structures cause extra mass‐to‐charge (m/z) increases in online hydrogen/deuterium exchange (HDX) in addition to hydroxyl or amine protons. Online HDX and exact mass measurement were used herein to characterize this extra increase property, and to further confirm proposed metabolite structures.

METHODS

Metabolites of two proprietary compounds as well as two commercially available compounds were analyzed using aqueous and HDX liquid chromatography coupled with an LTQ‐Orbitrap. The exact mass measurements of both the precursor ions and product ions were acquired through data‐dependent acquisition and compared with theoretical values of proposed fragment ions.

RESULTS

Analysis of exact mass measurements of metabolite product ions under both normal aqueous and HDX conditions led to the identification of the isoxazole ring opening of compound C‐1, and a double‐bond formation on the methylpyrrolidine ring of compound C‐2 during biotransformation. In both cases, imine or enamine structures formed in the metabolites caused extra m/z increases upon HDX that contributed confirmatory information to the structure identification. The compound 3,3‐diphenyl‐2‐ethyl‐1‐pyrroline also demonstrated that the methylene protons adjacent to the imine were exchanged during online HDX.

CONCLUSIONS

The exchangeability of methylene protons adjacent to imine or enamine moieties proved to be useful to narrow down or even pinpoint the metabolism sites of parent drugs when high‐resolution exact mass measurement and online HDX were used. Copyright © 2012 John Wiley & Sons, Ltd.
Surface sputtering with nanoclusters: the relevant parameters
Authors: Delcorte A. , Restrepo O. A. , Czerwinski B. , Garrison B. J.
Published: March 2012

In this contribution, we compare the results of our recent molecular dynamics simulations with data already published by us and by other authors to identify the relevant physical parameters governing observables such as the range, the damaged volume, the crater shape, the sputtering yield, the emission of molecules and fragments, and the chemical reactions induced in organic solids by cluster projectiles. Among the considered physical quantities, we show for instance that the total cluster energy, the energy per atom/per nucleon in the cluster and, importantly, the mass matching between the cluster and target constituents have a major effect on the physics of the interaction. The evolution of the observables as a function of these basic physical parameters is illustrated and discussed as well as certain implications for organic surface characterization using cluster ion beams. Copyright © 2012 John Wiley & Sons, Ltd.
Aktuelle Untersuchungen zum Verhalten von Verbundglas unter Schneelasteinwirkung
Authors: Näßl Andreas , Mensinger Martin , Martin  , Bucak Ömer
Published: March 2012

Der Schubverbund von Verbundglas wird durch das zeit‐ und temperaturabhängige viskoelastische Materialverhalten der polymeren Zwischenschicht geprägt. Obwohl für langdauernde Lasten oftmals vernachlässigt, verspricht der Schubverbundansatz beim Lastfall Schnee aufgrund temperaturbedingt begünstigter Zwischenschichteigenschaften wirtschaftliches Anwendungspotential. Dieser Beitrag berichtet über aktuelle Versuchsergebnisse, die durch Langzeit‐Monitoring an Freilandprüfständen unter Schneelastereignissen gewonnen wurden. Die Untersuchungen sind Bestandteil des laufenden DFG‐Forschungsprogrammes “Identifizierung tragfähigkeitssteigernder Eigenschaften von Verbundglas“.

Recent experimental results about the behaviour of laminated glass exposed to snowfall events. The shear coupling of laminated glass is decisively affected by the time‐ and temperature‐dependent viscoelastic material properties of the polymeric interlayer. Though often neglected for long‐term load situations, the shear coupling promises to be applicable and economically relevant for the load case snow, by reason of enhanced interlayer material properties, associated to the temperature conditions. This paper reports on recent experimental results obtained by long‐term monitoring of free‐air test facilities for laminated glass exposed to snowfall events. The investigations are part of the ongoing research program “Identification of bearing capacity enhancing characteristics of laminated glass“, funded by the DFG (German Research Foundation).
Deformations‐ und Bruchverhalten von Verbundsicherheitsglas unter dynamischer Beanspruchung
Authors: Kolling Stefan , Alter Christian , Schneider Jens , Kuntsche Johannes , Gebbeken Norbert , Larcher Martin
Published: March 2012

Der vorliegende Beitrag gibt einen Überblick bezüglich aktueller Fragestellungen im Bereich der numerischen Berechnung von Sicherheitsverglasungen und der Tragfähigkeit von Glas unter Kurzzeiteinwirkung. Es werden Untersuchungen zur Widerstandsfähigkeit von Verbundsicherheitsglas mittels Pendelschlagversuch (weicher Stoß) und Detonationsbeanspruchung diskutiert. Hierbei werden sowohl das Deformationsverhalten als auch das Resttragfähigkeitsverhalten der Verglasung berücksichtigt. Verschiedene Modellierungsmethoden zur numerischen Simulation des Verbundmaterials mit Hilfe der Finiten‐Elemente‐Methode werden aufgezeigt und mit experimentellen Befunden kritisch verglichen. Das dynamische Verhalten von Verbundsicherheitsglas wird dabei sowohl über implizite als auch explizite Zeitintegrationsverfahren beschrieben.

Deformation behavior of laminated glass under dynamic loading. The purpose of the present paper is to give an overview of current modeling techniques for the finite element simulation of laminated glass under dynamic loading. Deformation and the post‐breakage behavior of laminated glass are discussed by means of impact and blast loading. Numerical results using different modeling techniques for the numerical simulation of the composite are presented and compared critically to experimental observations. The time integration for the dynamic response of laminated glass is performed by both implicit and explicit finite element solvers.