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User Modeling and User-Adapted Interaction - Adaptive learning systems collect data on student performance and use them to personalize system behavior. Most current personalization techniques focus... 相似文献
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Christian Hintze Radek Stoček Thomas Horst René Jurk Sven Wiessner Gert Heinrich 《Polymer Engineering and Science》2014,54(12):2958-2964
Short fiber reinforcement is a suitable way to improve the tribological properties of elastomers. However, rubbers products are often exposed to highly dynamic mechanical loadings. Hereby it is crucial to study the change in dynamic behavior due to the addition of short fibers. Therefore, these properties were investigated in terms of dynamic mechanical thermal analysis, heat build‐up (HBU), and fatigue crack growth resistance under cyclic loadings for two different rubber compounds. A peroxide cured ethylene–propylene–diene rubber (EPDM) and a sulfur cured natural rubber (NR) compound were chosen and reinforced with two types of short aramid fibers. It was found that the short fibers could contribute to the improvement in the crack growth resistance, HBU, and the dynamic mechanical behavior of the composites depending on the testing conditions. POLYM. ENG. SCI., 54:2958–2964, 2014. © 2014 Society of Plastics Engineers 相似文献
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Bakandritsos A Papagiannopoulos A Anagnostou EN Avgoustakis K Zboril R Pispas S Tucek J Ryukhtin V Bouropoulos N Kolokithas-Ntoukas A Steriotis TA Keiderling U Winnefeld F 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(15):2381-2393
Hybrid magnetic drug nanocarriers are prepared via a self-assembly process of poly(methacrylic acid)-graft-poly(ethyleneglycol methacrylate) (p(MAA-g-EGMA)) on growing iron oxide nanocrystallites. The nanocarriers successfully merge together bio-repellent properties, pronounced magnetic response, and high loading capacity for the potent anticancer drug doxorubicin (adriamicin), in a manner not observed before in such hybrid colloids. High magnetic responses are accomplished by engineering the size of the magnetic nanocrystallites (~13.5 nm) following an aqueous single-ferrous precursor route, and through adjustment of the number of cores in each colloidal assembly. Complementing conventional magnetometry, the magnetic response of the nanocarriers is evaluated by magnetophoretic experiments providing insight into their internal organization and on their response to magnetic manipulation. The structural organization of the graft-copolymer, locked on the surface of the nanocrystallites, is further probed by small-angle neutron scattering on single-core colloids. Analysis showed that the MAA segments selectively populate the area around the magnetic nanocrystallites, while the poly(ethylene glycol)-grafted chains are arranged as protrusions, pointing towards the aqueous environment. These nanocarriers are screened at various pHs and in highly salted media by light scattering and electrokinetic measurements. According to the results, their stability is dramatically enhanced, as compared to uncoated nanocrystallites, owing to the presence of the external protective PEG canopy. The nanocarriers are also endowed with bio-repellent properties, as evidenced by stability assays using human blood plasma as the medium. 相似文献
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Di Li Pengtao Jing Lihuan Sun Yang An Xinyan Shan Xinghua Lu Ding Zhou Dong Han Dezhen Shen Yuechen Zhai Songnan Qu Radek Zbořil Andrey L. Rogach 《Advanced materials (Deerfield Beach, Fla.)》2018,30(13)
Carbon dots (CDs) have significant potential for use in various fields including biomedicine, bioimaging, and optoelectronics. However, inefficient excitation and emission of CDs in both near‐infrared (NIR‐I and NIR‐II) windows remains an issue. Solving this problem would yield significant improvement in the tissue‐penetration depth for in vivo bioimaging with CDs. Here, an NIR absorption band and enhanced NIR fluorescence are both realized through the surface engineering of CDs, exploiting electron‐acceptor groups, namely molecules or polymers rich in sulfoxide/carbonyl groups. These groups, which are bound to the outer layers and the edges of the CDs, influence the optical bandgap and promote electron transitions under NIR excitation. NIR‐imaging information encryption and in vivo NIR fluorescence imaging of the stomach of a living mouse using CDs modified with poly(vinylpyrrolidone) in aqueous solution are demonstrated. In addition, excitation by a 1400 nm femtosecond laser yields simultaneous two‐photon‐induced NIR emission and three‐photon‐induced red emission of CDs in dimethyl sulfoxide. This study represents the realization of both NIR‐I excitation and emission as well as two‐photon‐ and three‐photon‐induced fluorescence of CDs excited in an NIR‐II window, and provides a rational design approach for construction and clinical applications of CD‐based NIR imaging agents. 相似文献
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Wojciech ?órawski Rafa? Chatys Norbert Radek Joanna Borowiecka-Jamrozek 《Surface & coatings technology》2008,202(18):4578-4582
The study analyses the tribological properties of a composite plasma sprayed with Al2O3-3TiO2 mixed in various proportions with CaF2, which is known as a solid lubricant. The coatings were plasma-sprayed in air and were tested using a pin-on-disc tribological set-up. The tests enabled to study their wear resistance and determine the coefficient of friction on the basis of friction force obtained in the course of continuous measurement at a set load. Experiments were optimized by the use of the two-level experiment design aimed at finding the optimal content of CaF2 in the composite. The influence of the spraying parameters on the coefficient of friction, hardness and surface roughness was determined by means of regression analysis. Metallographical studies of the plasma-sprayed composite were conducted with the use of a scanning microscope with an energy dispersion spectrometer (EDS). 相似文献
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Alkaline phosphodiesterase I was demonstrated in human glomerular mesangial cells (HGEC) as an ectoenzyme. Treatment of HGEC by dexamethasone increased surface phosphodiesterase I activity in a dose- and time-dependent manner. Maximal increase of phosphodiesterase I activity, about twice, occurred after treatment with 5 microM dexamethasone for 6 days. Cycloheximide prevented and RU 38486, a glucocorticoid receptor antagonist, suppressed the dexamethasone induced increase in phosphodiesterase I activity. This study shows that HGEC have a surface phosphodiesterase I controlled by glucocorticoids through a receptor-mediated mechanism. 相似文献