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141.
Knowledge is knowledge is knowledge? The relationship between personal and scientific epistemologies
Iris Tabak Michael P. Weinstock 《Canadian Journal of Science, Mathematics, & Technology Education》2013,13(3):307-328
Abstract: In this paper, we explore cross‐domain versus domain‐specific scientific epistemological understanding. Research about relationships between such understandings shows mixed results. The ambiguities may result from the instruments used. Unlike most studies, we combined instruments from the personal‐ and science‐epistemology research traditions. Students in Grades 6 to 9 in a science‐centred school completed adaptations of the Epistemological Thinking Assessment (ETA) (Kuhn, Cheney, & Weinstock, 2000) and the Views of Science‐Technology‐Society (VOSTS) (Aikenhead & Ryan, 1992) instruments. Regular‐school students in Grades 7 and 9 also completed the ETA. Developmental patterns on the ETA emerged as expected in both schools. However, the science‐centred students’ views of knowledge in the social and physical domains seem more differentiated and sophisticated. Their performance on the VOSTS tended toward higher scores, although lower than expected. There was no significant relationship between performance on the ETA and on the VOSTS. The findings propose domain‐specific aspects of epistemological understanding and development. 相似文献
142.
Comparison between the influence of applied electrode and electrolyte temperatures on porous anodizing of aluminium 总被引:1,自引:0,他引:1
Tim Aerts Jean-Baptiste Jorcin Iris De Graeve Herman Terryn 《Electrochimica acta》2010,55(12):3957-3965
A new approach for studying the effect of temperature on anodic oxide growth on aluminium is presented in this paper. Using an in-house developed electrode holder, anodizing is performed under conditions of applied and controlled electrode temperature. The influence of temperature on the process is evaluated by experiments in a broad temperature range for both the electrode and the electrolyte temperature. The electrochemical behaviour of the aluminium electrodes is demonstrated to be more susceptible to variations of the electrode temperature than to variations of the electrolyte temperature. Concerning the morphology of the anodic film it is shown that by cooling the electrode a normal oxide layer could be grown at high electrolyte temperatures, whereas anodizing in a cool electrolyte at high electrode temperature results in a collapsed porous structure at the oxide surface. Furthermore, the electrode temperature affects the formation ratio of the oxide to a larger extent than the electrolyte temperature, indicating its important influence even on the level of the ionic conductivity during anodic oxide growth. All observations indicate that merely considering the electrolyte temperature upon studying the influence of temperature on the process is not sufficient; the electrode temperature is much more determining. 相似文献
143.
Pulsed corona discharge (PCD) in oxygen-nitrogen mixtures results in formation of nitrogen oxides, transformed to aqueous nitrates in contact with water. The experimental research into the impact of formate and oxalate to nitrate formation in aqueous solutions treated with PCD was undertaken. The impact of paracetamol, ibuprofen, indomethacin and their oxidation products to nitrate formation was also analyzed. Pharmaceuticals obstructed nitrate formation, while carboxylic anions and pharmaceuticals’ oxidation products noticeably improved nitrate formation in treated solutions as compared to water. The nitrate formation enhancement is explained by the aqueous ozone decomposition and hydroxyl radical formation known to be improved by carboxylic anions. 相似文献
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Majda Sfiligoj Smole Kristina Stakne Karin Stana Kleinschek Manja Kurecic Marjan Bele Diana Gregor Svetec Volker Ribitsch 《应用聚合物科学杂志》2009,113(2):1276-1281
Nanocomposite fibers based on polypropylene (PP) polymer were prepared with different content of nanofiller. Filaments were spun from an isotactic iPP homopolymer. Montmorillonite modified by N,N‐dimethyl‐N,N dioctadecylammonium cations was used for preparation of PP nanocomposite fibers. A PP grafted with acrylic acid was added as a coupling agent. Nanocomposite fibers were characterized, i.e., the surface morphology of PP nanocomposite fibers was observed and surface properties were defined by electrokinetic properties determination by zeta potential measurements. For particle distribution observation the plasma etching was involved as a method for sample preparation. The addition of nanoparticles has an impact on ZP value of nanofilled fibers, however, isoelectric point IEP is not significantly influenced by different concentrations of nanofiller. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
147.
Zhao F Harnisch F Schröder U Scholz F Bogdanoff P Herrmann I 《Environmental science & technology》2006,40(17):5193-5199
The performance of oxygen reduction catalysts (platinum, pyrolyzed iron(ll) phthalocyanine (pyr-FePc) and cobalt tetramethoxyphenylporphyrin (pyr-CoTMPP)) is discussed in light of their application in microbial fuel cells. It is demonstrated that the physical and chemical environment in microbial fuel cells severely affects the thermodynamics and the kinetics of the electrocatalytic oxygen reduction. The neutral pH in combination with low buffer capacities and low ionic concentrations strongly affect the cathode performance and limit the fuel cell power output. Thus, the limiting current density in galvanodyanamic polarization experiments decreases from 1.5 mA cm(-2) to 0.6 mA cm(-2) (pH 3.3, E(cathode) = 0 V) when the buffer concentration is decreased from 500 to 50 mM. The cathode limitations are superposed by the increasing internal resistance of the MFC that substantially contributes to the decrease of power output. For example, the maximum power output of a model MFC decreased by 35%, from 2.3 to 1.5 mW, whereas the difference between the electrode potentials (deltaE = E(anode) - E(cathode)) decreased only by 10%. The increase of the catalyst load of pyr-FePc from 0.25 to 2 mg cm(-2) increased the cathodic current density from 0.4 to 0.97 mA cm(-2) (pH 7, 50 mM phosphate buffer). The increase of the load of such inexpensive catalyst thus represents a suitable means to improve the cathode performance in microbial fuel cells. Due to the low concentration of protons in MFCs in comparison to relatively high alkali cation levels (ratio C(Na+,K+)/C(H+) = 5 x E5 in pH 7, 50 mM phosphate buffer) the transfer of alkali ions through the proton exchange membrane plays a major role in the charge-balancing ion flux from the anodic into the cathodic compartment. This leads to the formation of pH gradients between the anode and the cathode compartment. 相似文献
148.
149.
Iris Lamparth Urs K. Fischer Juraj Pavlinec Angela Kleinova Norbert Moszner 《大分子材料与工程》2014,299(7):834-842
150.
Nuno Gil Iris D. Tommelein Art Stout Thomas Garrett 《Canadian Metallurgical Quarterly》2005,131(4):439-448
Four factors make it challenging to manage semiconductor fabrication facility (“fabs”) projects: technical complexity of the product design, need to compress the project duration, need to reduce upfront costs, and unexpected project changes. The strategies employed by practitioners to cope with these challenges form an intricate puzzle. We empirically develop a framework that provides a structure for helping to solve this puzzle, which comprises two principles: investing upfront in a flexible product design and structuring a flexible process. Empirical findings reveal that project teams make commitments early on by overdesigning but also postpone critical decisions by differentiating the scope of their work. Project teams employ other strategies such as increasing communication, using modular architectures, engaging in four-dimensional computer-based modeling, and fabricating components and subsystems off-site. Our analysis yields understanding on the purposes and performance tradeoffs of these strategies, and on how they embody the two principles. Project managers may find the framework useful when deciding which strategies best suit other equally challenging projects. 相似文献