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991.
Daniel Fechner Norbert Hort Carsten Blawert Hajo Dieringa Michael St?rmer Karl Ulrich Kainer 《Journal of Materials Science》2012,47(14):5461-5469
The increasing use of magnesium castings for automotive components and the number of newly developed alloys raise the question
of suitable recycling processes. Remelting offers a high potential of energy saving and thereby improves the live cycle balance
of magnesium components. Effective recycling processes are likely to involve the mixing of different alloys but little is
known about the interaction of alloying elements. In order to approach this issue, the influence of strontium, silicon and
calcium on phase formation and mechanical properties of magnesium alloy AM50 has been investigated. After strontium addition,
X-ray diffraction demonstrated the formation of the Al4Sr and the Mg17Sr2 phases. However, after simultaneous alloying with strontium, silicon and calcium the ternary Zintl phase Sr6.33Mg16.67Si13 was detected. This phase forms preferably instead of Al4Sr, Mg17Sr2 and Mg2Si. Compared to the two strontium-containing phases, precipitates of the ternary Zintl phase exhibit a rather compact morphology.
This results in a higher elongation-at-fracture under tensile stress. 相似文献
992.
Neng Qiu Huabing Yin Bozhi Ji Norbert Klauke Andrew Glidle Yongkui Zhang Hang Song Lulu Cai Liang Ma Guangcheng Wang Lijuan Chen Wenwen Wang 《Materials science & engineering. C, Materials for biological applications》2012,32(8):2634-2640
Biogenic calcium carbonate has come to the attention of many researchers as a promising drug delivery system due to its safety, pH sensitivity and the large volume of information already in existence on its medical use. In this study, we employed bovine serum albumin (BSA) as an additive to synthesize a series of porous calcium carbonate microspheres (CCMS). These spheres, identified as vaterite, are stable both in aqueous solutions and organic solvents. Camptothecin, an effective anticancer agent, was loaded into the CCMS by simple diffusion and adsorption. The camptothecin loaded CCMS showed sustained cell growth inhibitory activity and a pH dependent release of camptothecin. With a few hours, the release is negligible under physiological conditions (pH = 7.4) but almost complete at pH 4 to 6 (i.e. pHs found in lysosomes and solid tumor tissue respectively). These findings suggest that porous, biogenic calcium carbonate microspheres could be promising carriers for the safe and efficient delivery of anticancer drugs of low aqueous solubility. 相似文献
993.
Organic UV‐protective coatings for polycarbonate glazing Polycarbonate as glazing material in outdoor applications requires functional UV protective and scratch resistant coatings. The vacuum coating technology offers a wide range of deposition processes to produce such complex coatings. The Fraunhofer IOF developed an effective UV protection by the deposition of organic UV absorbers. Thermal evaporated organic compounds were investigated as single layers and hybrid layers in a SiO2 matrix. The UV‐stability of such coatings was increased significantly. 相似文献
994.
Novel aromatic mono‐ and di(phosphonate) or phosphonic acid monomers for use in dental composites were synthesized. Synthesis of monomer 1a involved three steps: (i) reaction of t‐butyl α‐bromomethacrylate (t‐BuBMA) and Bisphenol A, (ii) conversion to diacid chloride derivative using thionyl chloride, (iii) reaction of diacid chloride with diethyl (2‐hydroxyphenyl) phosphonate. Monomer 2a was synthesized from the reaction of 2‐chloromethacryloyl chloride and diethyl (2‐hydroxyphenyl) phosphonate. Synthesis of monomer 3a involved reaction of glycidyl methacrylate (GMA) with diethyl (2‐hydroxyphenyl) phosphonate. Hydrolysis of the phosphonate groups of monomers 1a and 2a with trimethylsilyl bromide (TMSBr) gave monomers 1b and 2b with phosphonic acid functionality, which is intended to improve binding ability of dental composites. The homopolymerization and copolymerization behaviors of the synthesized monomers with (Bis‐GMA) were investigated using photodifferential scanning calorimetry at 40°C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as photoinitiator. The interaction of the monomer 1b with hydroxyapatite (HAP) was investigated using Fourier transform infrared technique. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
995.
An Activity Recognition System For Mobile Phones 总被引:1,自引:1,他引:0
We present a novel system that recognizes and records the motional activities of a person using a mobile phone. Wireless sensors
measuring the intensity of motions are attached to body parts of the user. Sensory data is collected by a mobile application
that recognizes prelearnt activities in real-time. For efficient motion pattern recognition of gestures and postures, feed-forward
backpropagation neural networks are adopted. The design and implementation of the system are presented along with the records
of our experiences. Results show high recognition rates for distinguishing among six different motion patterns. The recognized
activity can be used as an additional retrieval key in an extensive mobile memory recording and sharing project. Power consumption
measurements of the wireless communication and the recognition algorithm are provided to characterize the resource requirements
of the system. 相似文献
996.
Faserbewehrter Beton wird heute zunehmend auch bei Tunnelbauwerken (Tunnelinnenschalen, Tübbinge) eingesetzt. Wesentliche Vorteile sind das hohe Tragvermögen, das daraus entstehende Einsparungspotential an herkömmlicher stabförmiger Bewehrung (Biegebewehrung, Bügelbewehrung in der Randzone), die Aufnahme von Spaltzugbeanspruchungen durch die Fasern, Rissbreitenbegrenzung, erhöhte Dauerhaftigkeit, verbesserter Brandwiderstand (insbesondere bei Verwendung von Kunststofffasern), Optimierung der Arbeitsabläufe etc. Neue Entwicklungen in der Betontechnologie haben in den letzten Jahrzehnten den faserbewehrten ultrahochfesten Beton (engl. UHPFRC – Ultra High Performance Fibre Reinforced Concrete) hervorgebracht. Im Rahmen dieser Arbeit wird der Einsatz des ultrahochfesten, stahlfaserbewehrten Betons beim zweischaligen Tübbingausbau untersucht. Als Referenzobjekt dient die derzeit im Bau befindliche Tunnelkette Perschling, die im Zuge des viergleisigen Ausbaus der Westbahnstrecke der Österreichischen Bundesbahnen (ÖBB) in Niederösterreich errichtet wird. Ziel der statischen Untersuchung ist es, unter der Randbedingung, dass die maximalen Verformungen des C 40/50‐Normalbetontübbings gemäß Ausschreibungsstatik nicht überschritten werden, herauszufinden, inwieweit die Schalendicke durch Einsatz einer alternativen UHPFRC‐Tübbingschale reduziert und dadurch wirtschaftliche Vorteile generiert werden können. Investigations on the application of Ultra‐High‐Performance‐Fibre‐Reinforced‐Concrete (UHPFRC) tunnel segments at the double shell lining construction. Today fibre reinforced concrete is increasingly applied for tunnel construction (tunnel linings, tunnel segments). The essential benefits are e.g. the higher load bearing capacity, savings potential on the conventional bending and binder reinforcement, the absorption of splitting forces by the fibres, crack width limitation, higher durability, improved fire resistance, optimization of the workflow, etc. Beside the steel fibres carbon or glass fibres and polypropylene fibres are being added increasingly. Recent developments in concrete technology have produced the Ultra‐High‐Performance Fibre‐Reinforced‐Concrete. This work examines the use of UHPFRC at the double shell segmental lining system. As reference object serves the currently constructed tunnel chain Perschling which is part of the four track west railway route extension in Lower Austria. The aim of the analysis is the design of an alternative UHPFRC shell with minimum thickness while maintaining the constraint that the deformations are not exceeding those in the tender design with its C 40/50 reinforced concrete segments. 相似文献
997.
Julia Wagner Mark Gruber Alexander Hinderhofer Andreas Wilke Benjamin Bröker Johannes Frisch Patrick Amsalem Antje Vollmer Andreas Opitz Norbert Koch Frank Schreiber Wolfgang Brütting 《Advanced functional materials》2010,20(24):4295-4303
Small‐molecule photovoltaic cells using diindenoperylene (DIP) as a new donor material in combination with the fullerene C60 as an electron acceptor are demonstrated. In addition to the successful application in planar and bulk heterojunction devices, a comprehensive analysis including structural studies, the determination of the energy level alignment and electrical transport investigations is given, stressing the correlation between growth conditions, film morphology, and device performance. Due to pronounced crystallinity and a large surface area of DIP films grown at elevated temperature, exceptionally high fill factors of almost 75% are achieved in planar heterojunction cells. Bulk heterojunctions exhibit large‐scale phase separation forming a bicontinuous network of both molecular species, which enables efficient exciton dissociation and charge carrier transport. The high ionization potential of DIP and the favorable energy level alignment with the fullerene C60 yield large open circuit voltages close to 1 V and comparable power conversion efficiencies of about 4% in both cell architectures. 相似文献
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