研究领域
We are working in an industry-academic research consortium dedicated to developing an SOFC power plant for mobile applications. The SOFC has found many applications in stationary power plant solutions but when the same technology migrates to a mobile platform, several new issues arise and are at the heart of what we are investigating: (a) Start-up time. The high temperature (1000 K) operation, ceramic brittleness, and numerous interfaces with thermal expansion differentials have called for slow start-up times, which must be reduced for mobile applications. (b) Dynamic load response. In stationary applications, SOFCs are powered to produce stable base load energy needs.
A mobile application, however, experiences constant changing power demands – acceleration, braking, idling in traffic, cruising at highway speeds, etc. – and this requires a cell stack design that is able to respond to this changing demand. (c) Volume commensurate with application. While stationary applications can be quite large, our solution needs to be scaled in size to appropriately power a car without occupying more space than is normally found in the engine compartment. We are tackling these challenges through a combination of novel material choices and advanced thin film deposition techniques, including pulse laser deposition (PLD) and atomic layer deposition (ALD). We are forming dense, extremely thin films and testing them for their applicability in this application.
Nickel Carbonyl Refining
Metalic nickel produced by the process
We are working with a global industrial partner to explore chemical details surrounding the refining of Ni ore use the Ni(CO)4 or Mond, process. To date, we have focussed on understanding the NiO reduction step in the refining process. Following extraction, various mechanical operations on the ore, and an oxidative roasting, the NiO powder is reduced to the impure Ni powder that is refined using the carbonyl Mond process. The reduction step has had several puzzling aspects to it, including the effect of some additives, the presence of different impurities, and the chemical mechanism at the heart of the process. We have resolved a number of issues and are making recommendations to the company regarding future ore processing procedures.
Studying the Grading Effectiveness of Large Groups of Graders
Picture of someone grading an exam
In large classes (we have upwards of 2000 students in our first-year chemistry courses), exams must either be entirely multiple choice in format or large groups of graders, drawn from the Teaching Assistant pool, must be assembled to grade these en masse. The challenge is to ensure the accuracy and fairness of the grading across the entire class. We have been developing new statistical measures with which to compare the variance of grading that is found in an effort to measure the effectiveness of tools used to train graders and ensure the success of the grading process. We have been applying this to our first year grading process and have so far identified the range of correlation anticipated and how certain training activities may have an impact. Work in this area is ongoing.
Conceptual Learning Tendencies and Student Performance
A plot showing a data set with a linear regression
We have worked with some American colleagues to find ways to determine student’s approach to learning and how this may effect their scholastic performance. A psychometric instrument developed at the University of Washington in St. Louis is proving successful at identifying students who rely on rote learning techniques as compared to those who have a more theory-based approach: this is able to classify students who extend their learning into new situations compared to those who are only able to solve problems exactly like ones they have solved previously. We have categorized the students in our first year classes here at Guelph using this instrument and have compared their performance based upon their learning approach. The hope is to identify students with exemplar (rote) learning tendencies and develop interventions to help them become more expert learners
Psychometrics and the Learning of Chemistry
Marking a bubble sheet test
One of the challenges that physical scientists have in undertaking serious educational research lies in recognizing that while chemistry is a physical science, the learning of chemistry is a social science. The study of that learning requires scientific approaches that are different than what we are used to employing. We must use a much deeper understanding of statistical methods than is commonly done. We have developed computer codes the apply Item Response Theory (IRT) and Classical Test Theory (CTT) to the exams undertaken by students in our first year chemistry classes, based on Joint Maximum Likehood Estimations and Marginal Maximum Likelihood Estimations. We are also working to develop a Bayesian routine. All of these can be used to characterize both student performance and exam quality. With this we hope to get a better understanding of student performance, and things that make exam questions particularly effective in exam settings.
Effectiveness of POGIL Materials in Learning Chemistry
An image showing a scattered green dots, and a graph suggesting a distribution.
In the mid-1990’s, a group of chemists developed a new instructional approach to chemistry labelled Process Oriented Guided Inquiry Learning or POGIL. Since then it has grown significantly to included proponents in disciplines throughout arts, science, and the humanities. The word “Inquiry” indicates that the learning is accomplished by having students ask and solve questions, rather than just laying out the learning information for them. The “Guided” aspect is in opposition to “Open Inquiry”; the materials carefully guide the students rather than just “throwing them into the deep end”. It seeks to guide students to the needed information, while still preserving their inquiring engagement. “Process Oriented” implies that a major goal of the activity is helping students to develop the skill of learning - the process of knowledge acquisition, evaluation, and implementation. I have been working to implement or develop POGIL materials for both chemistry and nanoscience and I have come to several conclusions:
(1) student engagement is grounded in questions, not answers,
(2) POGIL materials need to consist mostly of questions, not statements,
(3) students need to have a tool with which they can interact to learn the relevant information,
(4) since students are more likely to challenge the statement of a peer than that of an instructor, they are more intellectually engaged in peer-to-peer learning as they are questioning the discussion, rather than just absorbing it, and
(5) students learn chemistry better within the context of relevant issues, rather than simply the chemistry itself.
I am developing new learning resources along these lines and will test them in the classroom in the future. I will arrange this so as to demonstrate the effectiveness of these tools compared to traditional POGIL materials (this is largely found in items 3 and 5 above) and as compared to the more standard lecture environment (which is different according to all 5 items above).
Evaluating Students' Scale Literacy
Ball and stick models of three molecules
近期论文
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1. Thomas, D. & Moore, M. (in press, 2016). From Nanometers to Kilometers and Beyond: Teaching Physical Properties Across Multiple Scales. Discussion on University Teaching, 1 (1).
2. Thomas, D. & Moore, M. (in press, 2016). Inter- and Intra-Rater Consistency: Armies of Graduate TAs Grading in First Year. Discussions on University Teaching, 1 (1).
3. Thomas, D. & Jones, L. A. (in press, 2016). Measuring Students' Approach to Learning. Discussions on University Teaching, 1 (1).
4. Thomas, D. & Pritchard, P. (in press 2016). Student Engagement Through Writing: An Undergraduate e-Journal Project. Chapter 15 in Integrating Library and Information Literacy Into Chemical Curricula (pp. 20).
5. Koczkur, K., Hamed, E., Chahma, M., Thomas, D., & Houmam, A. (2014). Electron Transfer Initiated Formation of Covalently Bound Organic Layers on Silicon Surfaces. The Journal of Physical Chemistry Part C: Nanomaterials, Interfaces and Hard Matter, 118 (36), 20908-20915.
6. Houmam, A., Muhammad, H., Chahma, M., Koczkur, K., & Thomas, D. F. (2011). 4-Nitrophenyl Sulfenyl Chloride as a New Precurosr for Well-Ordered Aromatic SAMs on Gold Surfaces. Chemical Communications, 47, 7095-7097.
7. Kolodiazhnyi, T. V. & Thomas, D. F. (2010). Hysteresis in the I-V Tunneling Characteristics of n-Type BaTiO3 Ceramics. Journal of the American Ceramic Society, 83, 129.
8. Wu, G., Wen, J., Wang, J., Thomas, D. F., & Chen, A. (2010). A facile approach to synthesize N and B co-doped TiO2 Nanomaterials with Superior Visible-Light Response. Materials Letters, 64, 1728-1731.
9. Pritchard, P. & Thomas, D. F. (2010). Inspiring Writing in the Sciences: An Undergraduate Electronic Journal Project. ACM Inroads, 3.
10. Kafi, A., Ahmadalineshad, A., Wang, J., Thomas, D. F., & Chen, A. (2010). Direct Growth of Nanoporous Au and its Application in Electrochemical Biosensing. Biosensors and Bioelectronics, 25, 2458-2463.
11. Dadarwal, R., Namvar, A., Hall, J. C., Thomas, D. F., & Warriner, K. (2009). Organic Conducting Polymer Electrode Based Sensors for Detection of Salmonella Infecting Bacteriophages. Materials Science and Engineering, 29, 761-765.
12. Wang, J., Adams, B., Asmussen, R. M., Thomas, D. F., & Chen, A. (2009). Facile Synthesis and Electrochemical Properties of Intermetallic PtPb Nanodendrites. Chemistry of Materials, 21, 1716-1724.
13. Wang, J., Thomas, D., & Chen, A. (2008). Non-enzymatic Electrochemical Glucose Sensor Based on Nanoporous PtPb networks. Analytical Chemistry, 80 (4), 997-1004.
14. Wang, J., Holt-Hindle, P., MacDonald, D., Thomas, D. F., & Chen, A. (2008). Synthesis and Electrochemical Study of Pt-Based nanoporous Materials. Electrochimica Acta, 53 (23), 6944-6952.
15. Wu, G., Wang, J., Thomas, D. F., & Chen, A. (2008). Synthesis of F-doped Flower-like TiO2 Nanostructures with High Photoelectrochemical Activity. Langmuir, 24, 3503-3509.
16. Wang, J., Thomas, D. F., & Chen, A. (2008). Direct Growth of Novel Alloyed PtAu Nano-Dendrites. Chemical Communications, 5010-5012.
17. Peng, X., Wang, J., Thomas, D. F., & Chen, A. (2005). Tunable Growth of TiO2 Nanostructures on Ti Substrates. Nanotechnology, 16 (10), 2389.
18. Thomas, D. (2000). Porous Silicon. Chapter 3 in Volume IV, Handbook of Nanostructured Materials and Nanotechnology. Academic Press.
19. Thomas, D. (1999). Chemical Kinetic Measurements with the Scanning Tunneling Microscope. Bulletin of the Microscopical Society of Canada, 27 (2), 9.
20. Thomas, D., Kolodiazhnyi, T. V., & Belous, A. G. (1998). Scanning tunneling microscopy and spectroscopy of BaTiO3 ceramics. Journal of the European Ceramic Society, 18, 1637.
21. Jones, L., Yukseker, O., & Thomas, D. F. (1996). Dependence of Photochemically Etched Porous Silicon Formation on Photoetching Wavelength and Power. Journal of Vacuum Science and Technology.
22. Jones, L., Wei, F. X., & Thomas, D. F. (1995). Moveable Ultra-High Vacuum Sample Mount: Heating, Cooling and Temperature Measurement Capabilities. Review of Scientific Instruments, 66 (2), 1146.
23. Jones, L., Wei, F. X., & Thomas, D. F. (1995). Design and Implementation of a Heatable, All-glass Doser for Sensitive Organometallic Compounds in an Ultrahigh Vacuum Environment. Review of Scientific Instruments, 66, 4981.
24. Jones, L., Taylor, G. M., Wei, F. X., & Thomas, D. F. (1995). Chemical Etching of Silicon: Smooth, Rough and Glowing Surfaces. Progress in Surface Science, 50, 283.
25. Campbell, S. D., Jones, L., Nakamichi, E., Wei, F. X., Zajchowski, L. D., D.F. Thomas (1995). Spectral and Structural Features of Porous Silicon Prepared by Chemical and Electrochemical Etching Processes. Journal of Vacuum Science and Technology, 13, 1184.
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