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Problem analysis is taught in the classroomenvironment by having students solve problems that oftenhave ready solutions. Because classroom problems areoften solvable within an hour, problem analysis, as oneCEAB (Canadian Engineering Accreditation Board)graduate attribute, may be viewed separately from othergraduate attributes. Students participating inundergraduate research, however, learn problem analysisby also developing investigative skills, use of engineeringtools (Matlab, Excel), even communication skills. In thispaper we discuss our undergraduate research experiencefrom perspectives of mentor and mentee. Mentor'smotivation to recruit undergraduate research studentscould include (i) high probability of finding talentedstudents to work on project of relatively short duration(i.e., one year) and (ii) producing solutions to a variety ofproblems that could lead to research problems. Thesemotivations align well with motivations of undergraduateresearch mentees, i.e., experience in solving morerealistic (open-ended) problems and strengthening theirresearch portfolios. Generating "real world" problemscan be achieved by introducing student-proposed designor analysis project component into a third-year course.Projects completed can then be continued into summerresearch projects. Results from the summer projects inturn enrich the third-year course content. To makeundergraduate research experience more productive,mentor encourages mentee to write and present together aconference paper, such as CEEA 2018 Conference.National-level conference experience would strengthenstudent's research portfolio. Projects with highertechnical content could even be presented to engineeringconferences, which is what we are aiming for. We discussways to increase student participation. We provide acourse project template for faculty members who areinterested in adopting our experience into their teachingand research activities.

Escherichia coli multidrug resistance protein E (EmrE) is a four transmembrane α-helix protein, and a member of the small multidrug resistance protein family that confers resistance to a broad range of quaternary cation compounds (QCC) via proton motive force. The multimeric states of EmrE protein during transport or ligand binding are variable and specific to the conditions of study. To explore EmrE multimerization further, EmrE extracted from E. coli membranes was solubilized in anionic detergent, sodium dodecyl sulphate (SDS), at varying protein concentrations. At low concentrations (≤ 1 μM) in SDS–EmrE is monomeric, but upon increasing EmrE concentration, a variety of multimeric states can be observed by SDS-Tricine polyacrylamide gel electrophoresis (PAGE). Addition of the (QCC), tetraphenyl phosphonium (TPP), to SDS–EmrE samples enhanced EmrE multimer formation using SDS-Tricine PAGE. The relative shapes of EmrE multimers in SDS with or without TPP addition were determined by small angle neutron scattering (SANS) analysis and revealed that EmrE dimers altered in conformation depending on the SDS concentration. SANS analysis also revealed that relative shapes of larger EmrE multimers (≥ 100 nm sizes) altered in the presence of TPP. Circular dichroism spectropolarimetry displayed no differences in secondary structure under the conditions studied. Fluorescence spectroscopy of SDS–EmrE protein demonstrated that aromatic residues, Trp and Tyr, are more susceptible to SDS concentration than TPP addition, but both residues exhibit enhanced quenching at high ligand concentrations. Hence, EmrE forms various multimers in SDS that are influenced by detergent concentration and TPP substrate addition.

The two-year experience of teachingand redesigning a probability and statistics forengineers course at the Schulich School ofEngineering will be discussed through the lensof (i) writing and using a custom textbook forthe course and (ii) refocusing lectures onapplying concepts to solving problems. Thecourse redesign, for example, allows students todevelop conceptual and practical understandingon selecting the most appropriate probabilitydistribution for a given problem. The refocusingof lectures to problem solving proves very usefulfor students. Further textbook development isbriefly discussed.

Stress and displacement fields of a two-dimensional solid under plane strain are solved subject to surface reconstruction boundary conditions. The alternating lateral Dirac-δ forces at steps owing to the reconstruction obtained by Alerhand et al (1988 Phys. Rev. Lett. 61 1973–6) are recovered from the gradient of the stress field solution. Sinusoidal vertical and lateral displacements on a terrace are obtained, in addition to the vertical force distribution, in the direction normal to the surface. Reconstructed periodic terraces reduce their elastic energy by increasing their average width, but the elastic energy density reaches a finite limit with an increased terrace width. A like-oriented step–step interaction with the force dipole from the surface reconstruction, using the Marchenko–Parshin model, is considered and found to be repulsive. Reconstructed terraces of a vicinal surface are thermodynamically stable when the surface has a large dangling bond energy and a large miscut angle. Small miscut angle or small surface tension tends to destabilize the surface, although our result suggests that a multilayer configuration will metastabilize the terraces owing to the interface elastic mismatch.

A concise formula expressing the entropy of adatoms as a divergence of their flow due to diffusion and deposition flux is presented. Adatom-elastic strain interaction is provided by a canonical coupling between the diffusion flow and the deformation gradient of the strained layer. It is found that the zero of the free energy of an adatom-strained layer continuum system should be that of a coherent unstrained layer, thus necessarily neglecting the cohesive energy contribution, while for the adatom-unstrained continuum layer the zero corresponds to an equilibrium between the adatoms and free atoms, which involves the cohesive energy.

Island size distributions of three-dimensional Si1−xGex/Si(001) islands of varying Ge fractions (x=0.4–0.7) and thicknesses grown by ultrahigh vacuum chemical vapor deposition are studied. Size distributions for percolating islands obey the dynamic scaling hypothesis due to a random percolation process, only in the small island limit. Island morphologies strongly suggest the presence of Smoluchowski ripening, in which islands collide and ripen. Random percolation and Smoluchowski ripening are thus combined to analyze the size distributions. To understand the critical behavior of the islands, as exhibited by their size distributions, a mean-field theory for coherently strained island formation is formulated, by incorporating surface energy and strain relaxation. The resulting phase diagram shows that island formation in Si1−xGex/Si(001) occurs near the critical region. Order parameter fluctuations can be estimated by calculating the curvature energy for such a system, showing that the strain fluctuations a...

Efficiency of Rankine cycle as a function of working fluid molecule is modeled using the Redlich‐Kwong equation of state. We have evaluated 12 molecules, ranging from water to ethylene glycol, and have parameterized their individual performance on several material parameters, including heat capacity and compressibility. This research aims to understand at the molecular level what drives some molecules to perform better at certain temperature and pressure range of the Rankine cycle. Immediate applications we are interested in are geothermal power and solar thermal energy conversion.

Island size distributions of ripened ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}/\mathrm{Si}(001)$ $(x=0.3\ensuremath{-}0.7)$ islands exhibit a slow decay at small island sizes and an asymmetric bell-shaped distribution peaked at a large size. We explain the ripening process in ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}/\mathrm{Si}(001)$ islands by proposing a model based on random percolation and Smoluchowski ripening. Drawing an analogy with percolation theory, we use a shifted average height to represent the time variable, which is also applicable in the Smoluchowski ripening model; this shifted average height is used to analyze size distributions and correlation functions. Critical exponents derived from the site percolation model at $d=3$ agree with our measurements. Island diffusion $D\ensuremath{\propto}{s}^{\ensuremath{-}\ensuremath{\alpha}}$ leading to coalescence events, shows a weak dependence on size s: \ensuremath{\alpha}=0.28\ifmmode\pm\else\textpm\fi{}0.20, attributable to the inverse process of sequential incorporation of atoms at step edges due to the high stress concentration at island terrace perimeters. While random percolation dominates for small sizes regime, Smoluchowski ripening controls the distribution peak at large island sizes. Good agreement is obtained between the model and the measured island size distributions.

We construct a 3D model for coherent island formation by (i) using a novel 3D strain tensor to account for bulk strains and (ii) representing adatom diffusion as an external field that perturbs an otherwise flat strained layer. Equilibrium shapes of coherent islands and wetting layer thickness are obtained. Coherently compressed layers are typically unstable, but become stable in tension. Comparisons with Si1-xGex/Si(001) and Si0.5Ge0.5/Si1-xGex(001) layers are discussed.

We study the island size distributions of Xi 1-x Ge x /Si(001) (x equals 0.4 - .07) islands of varying Ge fractions and thicknesses by ultrahigh vacuum chemical vapor deposition. The island size distributions of the percolating islands obey a dynamic scaling hypothesis admitting only one length scale governing the growth, in the limit of large island sizes. Although bimodal distributions are found in coherent islands at large misfit strain, due to the large stress concentration at island perimeters; faulted dislocation loops forming as islands grow remove this stress concentration. This re-establishes a unimodal distribution,, reclaiming the scaling hypothesis. We show that the misfit strain is renormalized and, thus, is not essential in determining the size distribution. We also demonstrate evidence for Smoluchowski ripening mechanism occuring during growth. Finally, we discuss implications of these issues on achieving a uniform Xi 1-x Ge x /Si(001) island distribution, which is crucial for technological applications.

We report here on the fabrication of porous anodic alumina (PAA) films from commercially available impure aluminum foil. While the expensive ultrapure PAA films are restricted to potential applications in nanoelectrophotonics, the impure PAA films are more suitable for large-scale applications, such as in catalysis and filtration. The anodization current behavior and chemical composition of the resulting PAA films from impure and ultrapure foils were found to be similar for the same set of anodizing conditions. However, the PAA films from impure aluminum foil contained pore arrays of much smaller size and less consistently sized pores than those of PAA from ultrapure foils. We find that these qualities are improved by either annealing or electropolishing the aluminum foil prior to anodization, although not to the degree of PAA produced from ultrapure foils. Greater improvement is found for annealed foils compared to electropolished foils.

A model for coherent island formation in heteroepitaxial thin films is presented by focusing on the interplay between surface and strain relaxation energies. The resulting free energy is mapped onto the Landau free energy, and yields the local surface slope as the order parameter for island formation. Isotropic islands are found to exhibit second-order transitions. We argue that our model is appropriate for describing the nucleation and stability of island formation. The spinodal curve indicates that there exists an unstable regime where spinodal-like islands emerge as low-slope islands, even in a highly mismatched heteroepitaxial system.