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971.
Rolf Ploetzner Sandra Berney Mireille Bétrancourt 《Journal of Computer Assisted Learning》2020,36(6):838-860
In a systematic review, 194 studies on learning from animation were analysed. The analysis covers the learning domains, the representational characteristics of the animations, the assessed perceptual and cognitive achievements, and the assessment formats. Research on learning from animation focuses on assessing conceptual at the neglect of kinematic mental models. This is in contrast to an important rationale for making use of animations: that it needs to be learned what animations can specifically display, namely, how change in space and time occurs. This might explain why meta-analyses which compared the effectiveness of animations and static pictures found merely small overall effect sizes in favour of animations. To confirm this hypothesis, one meta-analysis was re-analysed with a new moderator. It encodes whether the features of the displayed changes were relevant to learning. Learning from animations was significantly more successful than learning from static pictures, if the features of the displayed changes had to be learned. 相似文献
972.
The structure-function relationship of the lipases from Pseudomonas aeruginosa and Bacillus subtilis 总被引:2,自引:0,他引:2
Misset Onno; Gerritse Gijs; Jaeger Karl-Erich; Winkler Ulrich; Colson Charles; Schanck Karin; Lesuisse Emmanuel; Dartois Veronique; Blaauw Mieke; Ransac Stephane; Dijkstra Bauke W. 《Protein engineering, design & selection : PEDS》1994,7(4):523-529
Within the BRIDGE T-project on lipases we investigate the structure-functionrelationships of the lipases from Bacillus subtilis and Pseudomonasaeruginosa. Construction of an overproducing Bacillus. strainallowed the purification of > 100 mg lipase from 30 l culturesupernatant. After testing a large variety of crystallizationconditions, the Bacillus lipase gave crystals of reasonablequality in PEG-4000 (38-45%), Na2SO4 and octyl-ß-glucosideat 22°C, pH 9.0. A 2.5 Å; dataset has been obtainedwhich is complete from 15 to 2.5 A resolution. P.aeruginosawild-type strain PAC1R was fermented using conditions of maximumlipase production. More than 90% of the lipase was cell boundand could be solubilized by treatment of the cells with TritonX-100. This permitted the purification of 50 mg lipase. So far,no crystals of sufficient quality were obtained. Comparisonof the model we built for the Pseudomonas lipase, on the basisof sequences and structures of various hydrolases which werefound to possess a common folding pattern (/ß hydrolasefold), with the X-ray structure of the P.glumae lipase revealedthat it is possible to correctly build the structure of thecore of a protein even in the absence of obvious sequence homologywith a protein of known 3-D structure. 相似文献
973.
A new type of interpenetrating polymer network was synthesized via photoinitiated free-radical polymerization of α,ω-methacryloyl terminated macromonomers prepared from epoxide-amine-adducts, followed by thermal addition polymerization of bisphenol-A diglycidyl ether and 4,4′-diaminodiphenylsulfone or 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0.2,6]decane. The interpenetrating polymer networks are optically transparent and show only one glass transition temperature ranging from -10 to 130°C, as a function of the macromonomer/addition polymer mixing ratio. The presence of a single phase was confirmed by scanning electron microscopy (SEM). 相似文献
974.
Constructional features of large-volume FRP vessels with internals. Especially in the case of large vessels with internals subject to corrosive attack (such as absorption towers and scrubbers in FGD plants) the use of FRP, particularly those based on vinyl ester resin, provides many advantages over conventional solutions such as stainless steel or rubber lining. The vessel's large dimensions may lead to relatively large deviations from target dimensions. In certain cases this may require departure from established design practice in order to ensure the benefit of easy on-site assembly and erection. The following article presents design details for large FRP vessels, i. e. fixing of internals inside the vessel, fixing of vessel on its foundations, and supporting of platforms and piping outside a free-standing tower. 相似文献
975.
Nadja Betzler Hans L. Bodlaender Robert Bredereck Rolf Niedermeier Johannes Uhlmann 《Algorithmica》2014,68(3):715-738
For directed and undirected graphs, we study how to make a distinguished vertex the unique minimum-(in)degree vertex through deletion of a minimum number of vertices. The corresponding NP-hard optimization problems are motivated by applications concerning control in elections and social network analysis. Continuing previous work for the directed case, we show that the problem is W[2]-hard when parameterized by the graph’s feedback arc set number, whereas it becomes fixed-parameter tractable when combining the parameters “feedback vertex set number” and “number of vertices to delete”. For the so far unstudied undirected case, we show that the problem is NP-hard and W[1]-hard when parameterized by the “number of vertices to delete”. On the positive side, we show fixed-parameter tractability for several parameterizations measuring tree-likeness. In particular, we provide a dynamic programming algorithm for graphs of bounded treewidth and a vertex-linear problem kernel with respect to the parameter “feedback edge set number”. On the contrary, we show a non-existence result concerning polynomial-size problem kernels for the combined parameter “vertex cover number and number of vertices to delete”, implying corresponding non-existence results when replacing vertex cover number by treewidth or feedback vertex set number. 相似文献
976.
The influence of incorporated 300 nm TiO2 (4 vol %), graphite (7 vol %), or combination of both fillers on the tribological performance of an epoxy resin was studied under various sliding load (10–40 N) and velocity conditions (0.2–3.0 m/s). Mechanical measurements indicated that the incorporation of TiO2 significantly enhanced the flexural and impact strength of the neat epoxy and the graphite including epoxy. Tribological tests were conducted with a cylinder‐on‐flat testing rig. The incorporation of nano‐TiO2 significantly improved the wear resistance of the neat epoxy under mild sliding conditions; however, this effect was markedly diminished under severe sliding conditions (high velocity and normal load). Nano‐TiO2 reduced the coefficient of friction only under severe sliding conditions. Graphite showed a beneficial effect in reducing the wear rate and the coefficient of friction of the neat epoxy. Compared to the nano‐TiO2‐filled epoxy, the graphite‐filled epoxy showed more stable wear performance with the variation of the sliding conditions, especially the normal load. A synergistic effect was found for the combination of nano‐TiO2 and graphite, which led to the lowest wear rate and coefficient of friction under the whole investigated conditions. The synergistic effect was attributed to the effective transfer films formed on sliding pair surfaces and the reinforcing effect of the nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2391–2400, 2006 相似文献
977.
Rolf Nordheim Nicholas J. Grant 《JOM Journal of the Minerals, Metals and Materials Society》1954,6(2):211-218
An extensive study was made of the aging characteristics of alloys based on the 80 pct Ni-20 pct Cr composition hardened with aluminum and/or titanium, each up to 4 pct. Aging was followed by means of hardness and hot electrical resistance measurements as well as by X-ray and microscopy. Stress rupture tests at 1500°F were utilized as a check on the predicted behavior. 相似文献
978.
Local repair procedure for carbon‐fiber‐reinforced plastics by refilling with a thermoset matrix 下载免费PDF全文
Kristin Küchler Elias Staiger Rolf‐Dieter Hund Olaf Diestel Martin Kirsten Chokri Cherif 《应用聚合物科学杂志》2016,133(6)
Textile‐reinforced composites have given rise to an increasingly important key technology for lightweight construction in aerospace, automotive, civil engineering, and many other industries. Because there exists no suitable repair procedure for carbon‐fiber‐reinforced plastics (CFRPs), damaged parts have to be replaced completely; this is extremely disadvantageous both ecologically and economically. With fiber‐reinforced composites used being more and more often, fast and efficient methods for the local repair of damaged CFRPs are essential. In this article, a novel repair procedure for CFRP is presented. The thermal activation by IR radiation of oxide semiconductors was used to locally degrade the thermoset matrix of the damaged CFRP through the maintenance of its structural stability and properties. The matrix‐free textile structure was then refilled with a thermoset epoxy matrix. Carbon fibers from the treated area were characterized with scanning electron microscopy, IR spectroscopy, thermogravimetric analysis, and subsequently, tensile strength for single fibers to verify the effectiveness of the procedure. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42964. 相似文献
979.
Design and Synthesis of Highly Active Peroxisome Proliferator‐Activated Receptor (PPAR) β/δ Inverse Agonists with Prolonged Cellular Activity 下载免费PDF全文
Dr. Philipp M. Toth Dr. Sonja Lieber Dr. Frithjof M. Scheer Tim Schumann Dr. Yvonne Schober Dr. Wolfgang A. Nockher Dr. Till Adhikary Dr. Sabine Müller‐Brüsselbach Prof. Dr. Rolf Müller Prof. Dr. Wibke E. Diederich 《ChemMedChem》2016,11(5):488-496
Based on 3‐(((4‐(hexylamino)‐2‐methoxyphenyl)amino)sulfonyl)‐2‐thiophenecarboxylic acid methyl ester (ST247, compound 2 ), a recently described peroxisome proliferator‐activated receptor (PPAR)β/δ‐selective inverse agonist, we designed and synthesized a series of structurally related ligands. The structural modifications presented herein ultimately resulted in a series of ligands that display increased cellular activity relative to 2 . Moreover, with methyl 3‐(N‐(2‐(2‐ethoxyethoxy)‐4‐(hexylamino)phenyl)sulfamoyl)thiophene‐2‐carboxylate (PT‐S264, compound 9 u ), biologically relevant plasma concentrations in mice were achieved. The compounds presented in this study will provide useful novel tools for future investigations addressing the role of PPARβ/δ in physiological and pathophysiological processes. 相似文献
980.
Cover Picture: Design and Synthesis of Highly Active Peroxisome Proliferator‐Activated Receptor (PPAR) β/δ Inverse Agonists with Prolonged Cellular Activity (ChemMedChem 5/2016) 下载免费PDF全文