Electrodeposition of rare earth-transition metal alloy thin films and nanostructures

Rare earth-transition metal alloys are of interest in MEMS and magnetic storage industries because of their unique magnetic properties. However, the applications of these alloys have been limited to bulk and thin film architectures because of the limitations of the contemporary vapor deposition technique to fabricate high aspect ratio nanostructures. The objective of this study is to develop an electrochemical process to deposit rare earth-transition metal alloys thus making it possible to deposit high aspect ratio nanostructures such as nanowires and nanotubes, which helps to tune their properties for specific applications. Electrodeposition of rare earth-transition metal alloys was achieved from an aqueous electrolyte kept under quiescent condition. The effect of cobalt (II) concentration, pH and deposition potential on rare earth-cobalt alloy electrodeposition was investigated. The alloy composition and the partial current densities exhibited a coupled deposition behavior between cobalt and rare earth. The rare earth concentration in the deposit and the current efficiency was found to depend on cobalt (II) concentration. Template electrodeposition of rare earth-transition metal alloy nanowires and nanotubes was demonstrated for the first time. Template deposition enabled the growth of several micron long deposits as compared to about 200 nm thick films deposited on planar substrate. Electrodeposition of rare earth-cobalt alloy nanotubes was observed from unmodified templates under low electrolyte pH, short deposition time and larger pore sizes. Also the composition of the deposit showed strong dependence to diffusion. The crystalline and magnetic properties investigation showed an amorphous deposit with small coercivity and squareness ratio. Compositionally modulated, electrodeposited, multilayered nanowires of CoGd/Co were also demonstrated. Based on the experimental results of rare earth-cobalt alloy deposition on planar electrodes and templates, an electrochemical reaction mechanism and a steady state kinetic model were presented. The mechanism showed a coupled behavior based on competitive adsorption of the intermediates. The kinetic model showed a good data fit between the experimental and simulated results

Instruments for visualization of self, co, and socially shared regulation of learning using multimodal analytics:a systematic review

Abstract. This thesis presents a systematic literature review in the intersection of multimodal learning analytics, regulation theories of learning, and visual analytics literature of the last decade (2011- 2021). This review is to collect existing research-based instruments designed to visualize Self-Regulation of Learning (SRL), Co-Regulation of learning (CoRL), and Socially Shared Regulation of learning (SSRL) using dashboards and multimodal data. The inclusion and exclusion criteria used in this review addressed two main aims. First, to distil settings, instruments, constructs, and audiences. Second, to identify visualization used for targets (i.e., cognition, motivation, and emotion), phases (i.e., forethought, performance, and reflection), and types of regulation (i.e., SRL, CoRL, and SSRL). By following the Preferred Reporting Items for Systematic Reviews and MetaAnalyses (PRISMA) guidelines, this thesis included 23 peer-reviewed articles out of 383 articles retrieved from 5 different databases searched in April 2021. The main findings from this literature review are (a) the included articles used theoretical grounding of SRL in all articles while CoRL is used only in 3 articles and SSRL only in 2 articles; (b) most articles used both teachers and students as the audience for visual feedback and operated in online learning settings; (c) selected articles focused mainly on visualizing cognition and motivation (17 articles each) as targets of regulation, while emotion as the target was applied only in 6 articles; (d) The performance phase was common to most of the articles and used various visualizations followed by reflection and forethought phases respectively. Simple visualizations, i.e., progress bar chart, line chart, color coding, are used more frequently than bubble chart, stacked column chart, funnel chart, heat maps, and Sankey diagram. Most of the dashboard instruments identified in the review are still improving their designs. Therefore, the results of this review should be put into the context of future studies to be utilized by researchers and teachers in recognizing the missing targets and phases of SRL, CoRL, and SSRL in visualized feedback. Addressing these could also assist them in giving timely feedback on students’ learning strategies to improve their regulatory skills

Entanglement entropy at higher orders for the states of a = 3 {\theta} = 1 Lifshitz theory

We evaluate the entanglement entropy of strips for boosted D3-black-branes compactified along the lightcone coordinate. The bulk theory describes $3$-dimensional $a = 3$ ${\theta} = 1$, Lifshitz theory on the boundary. The area of small strips is evaluated perturbatively up to second order, where the leading term has a logarithmic dependence on strip width l, whereas entropy of the excitations is found to be proportional to $l^4$. The entanglement temperature falls off as $\frac{1}{l^3}$ on expected lines. The size of the subsystem has to be bigger than the typical Lifshitz scale in the theory. At second order, the redefinition of temperature(or strip width) is required so as to meaningfully describe the entropy corrections in the form of the first law of entanglement thermodynamics.Comment: 15 Pages, typos corrected, sections modifie