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941.
942.
Andrew R. Bressette 《The Chemical Educator》2000,5(3):133-135
In recent years there has been increasing movement toward laboratory exercises that are inquiry-based, requiring students to assume more active roles in the learning process. A laboratory experiment was developed in this light, framed around a simple question, “Which freezes faster, hot water or cold water?” The experiment was used at the beginning of the general chemistry year-long course sequence and served as an introduction to the scientific process. Students were each asked to develop a hypothesis and then design a simple experiment to determine which freezes faster, hot water or cold water, using small cold baths to freeze the water. A strength of this experiment is that students not only design and perform the experiments, but at the end they evaluate each other’s methods. 相似文献
943.
944.
James McLaughlin Andrew V. Sills 《Journal of Mathematical Analysis and Applications》2008,344(2):765-777
We present several new families of Rogers-Ramanujan type identities related to the moduli 18 and 24. A few of the identities were found by either Ramanujan, Slater, or Dyson, but most are believed to be new. For one of these families, we discuss possible connections with Lie algebras. We also present two families of related false theta function identities. 相似文献
945.
The structural properties of a-Al2O3/Ge, a-Al2O3/In0.5Ga0.5As and a-Al2O3/In0.5Al0.5As/InGaAs interfaces were investigated by density-functional theory (DFT) molecular dynamics (MD) simulations. Realistic a-Al2O3 samples were generated using a hybrid classical-DFT MD “melt and quench” approach. The interfaces were formed by annealing at 700 K/800 K and 1100 K with subsequent cooling and relaxation. The a-Al2O3/Ge interface demonstrates pronounced interface intermixing and interface bonding exclusively through Al–O–Ge bonds generating high interface polarity. In contrast, the a-Al2O3/InGaAs interface has no intermixing, Al–As and O–In/Ga bonding, low interface polarity due to nearly compensating interface dipoles, and low substrate deformation. The a-Al2O3/InAlAs interface demonstrated mild intermixing with some substrate Al atoms being adsorbed into the oxide, mixed Al–As/O and O–Al/In bonding, medium interface polarity, and medium substrate deformation. The simulated results demonstrate strong correlation to experimental measurements and illustrate the role of weak bonding in generating an unpinned interface for metal oxide/semiconductor interfaces. 相似文献
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948.
Donald A. Ross Alexander H. Chu Thomas J. Nikolai Jon M. Ryan Donald G. Schaefer Andrew R. Schmidt 《Adsorption》1999,5(4):391-398
Continuous perfusion cell culture, using albumin containing medium, offers the potential advantages of higher recombinant Prourokinase (r-ProUK) yields, higher initial product purity and increased throughput compared to batch culture technology using medium supplemented with fetal bovine serum. We have characterized the production of r-ProUK in medium supplemented with a lipid rich bovine serum albumin (Albumax) in a perfusion system. The results of these studies showed that it was necessary to modify the r-ProUK batch recovery scheme to process r-ProUK from a perfusion system. To accommodate large volumes of perfusate harvested over a ten to fourteen day production cycle, cation exchange and hydrophobic interaction chromatography (HIC) resins were identified that had increased product binding capacity, better flow characteristics and wider pH ranges which allowed caustic cleaning. The mobile phase composition, pH and ionic strength were modified to improve r-ProUK yields from the identified resins, and procedures were developed to eliminate r-ProUK degradation products. Strategies were defined for processing continuous harvest, which contained four to seven times the amount of r-ProUK of batch harvests. 相似文献
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950.