Self-Regulated Learning in Undergraduate Science

Undergraduate science courses are particularly challenging for students transitioning into university. The departure from supportive high school environments can be difficult for students lacking self-directed and self-motivated learning skills. Many high-achieving school graduates entering higher education are surprised to discover they are ill-prepared to be accountable for their learning (Stanton et al., 2015). Over the past two decades, there has been a mounting interest in the pedagogical approaches aimed at equipping students with the capabilities of a lifelong learner (Australian Qualifications Framework, 2013; Oliver & Jorre de St Jorre, 2018; Boud & Dochy, 2010). Consequently, research efforts in higher education have attempted to identify the behavioural strategies and motivational states associated with academic success. Self-regulated learning (SRL) is an umbrella term encompassing the independent and self-directed strategies that allow students to recognise and regulate their learning (Dinsmore et al., 2008). In brief, self-regulation is what a lifelong learner does. In science disciplines, much attention has been directed towards curricula that facilitate the development of SRL in students, such that they become aware of, and maintain control over their learning of complex scientific concepts. This study reviews the current theoretical perspectives, methodological approaches, and emerging trends from research on SRL in higher education science

Deformation and Failure of a Multi-Wall Carbon Nanotube Yarn Composite

Forests of multi-walled carbon nanotubes can be twisted and manipulated into continuous fibers or yarns that exhibit many of the characteristics of traditional textiles. Macro-scale analysis and test may provide strength and stiffness predictions for a composite composed of a polymer matrix and low-volume fraction yarns. However, due to the nano-scale of the carbon nanotubes, it is desirable to use atomistic calculations to consider tube-tube interactions and the influence of simulated twist on the effective friction coefficient. This paper reports laboratory test data on the mechanical response of a multi-walled, carbon nanotube yarn/polymer composite from both dynamic and quasi-static tensile tests. Macroscale and nano-scale analysis methods are explored and used to define some of the key structure-property relationships. The measured influence of hot-wet aging on the tensile properties is also reported

Elastic Response and Failure Studies of Multi-Wall Carbon Nanotube Twisted Yarns

Experimental data on the stress-strain behavior of a polymer multiwall carbon nanotube (MWCNT) yarn composite are used to motivate an initial study in multi-scale modeling of strength and stiffness. Atomistic and continuum length scale modeling methods are outlined to illustrate the range of parameters required to accurately model behavior. The carbon nanotubes yarns are four-ply, twisted, and combined with an elastomer to form a single-layer, unidirectional composite. Due to this textile structure, the yarn is a complicated system of unique geometric relationships subjected to combined loads. Experimental data illustrate the local failure modes induced by static, tensile tests. Key structure-property relationships are highlighted at each length scale indicating opportunities for parametric studies to assist the selection of advantageous material development and manufacturing methods

Multi-scale Rule-of-Mixtures Model of Carbon Nanotube/Carbon Fiber/Epoxy Lamina

A unidirectional carbon fiber/epoxy lamina in which the carbon fibers are coated with single-walled carbon nanotubes is modeled with a multi-scale method, the atomistically informed rule-of-mixtures. This multi-scale model is designed to include the effect of the carbon nanotubes on the constitutive properties of the lamina. It included concepts from the molecular dynamics/equivalent continuum methods, micromechanics, and the strength of materials. Within the model both the nanotube volume fraction and nanotube distribution were varied. It was found that for a lamina with 60% carbon fiber volume fraction, the Young's modulus in the fiber direction varied with changes in the nanotube distribution, from 138.8 to 140 GPa with nanotube volume fractions ranging from 0.0001 to 0.0125. The presence of nanotube near the surface of the carbon fiber is therefore expected to have a small, but positive, effect on the constitutive properties of the lamina

Molecular Dynamics Simulations of Adhesion at Epoxy Interfaces

The effect of moisture on adhesives used in aerospace applications can be modeled with chemically specific techniques such as molecular dynamics simulation. In the present study, the surface energy and work of adhesion are calculated for epoxy surfaces and interfaces, respectively, by using molecular dynamics simulation. Modifications are made to current theory to calculate the work of adhesion at the epoxy-epoxy interface with and without water. Quantitative agreement with experimental values is obtained for the surface energy and work of adhesion at the interface without water. The work of adhesion agrees qualitatively with the experimental values for the interface with water: the magnitude is reduced 15% with respect to the value for the interface without water. A variation of 26% in the magnitude is observed depending on the water configuration at a concentration of 1.6 wt%. The methods and modifications to the method that are employed to obtain these values are expected to be applicable for other epoxy adhesives to determine the effects of moisture uptake on their work of adhesion

Rrd1p, an RNA polymerase II-specific prolyl isomerase and activator of phosphoprotein phosphatase, promotes transcription independently of rapamycin response.

Rrd1p (resistance to rapamycin deletion 1) has been previously implicated in controlling transcription of rapamycin-regulated genes in response to rapamycin treatment. Intriguingly, we show here that Rrd1p associates with the coding sequence of a galactose-inducible and rapamycin non-responsive GAL1 gene, and promotes the association of RNA polymerase II with GAL1 in the absence of rapamycin treatment following transcriptional induction. Consistently, nucleosomal disassembly at GAL1 is impaired in the absence of Rrd1p, and GAL1 transcription is reduced in the Δrrd1 strain. Likewise, Rrd1p associates with the coding sequences of other rapamycin non-responsive and inducible GAL genes to promote their transcription in the absence of rapamycin treatment. Similarly, inducible, but rapamycin-responsive, non-GAL genes such as CTT1, STL1 and CUP1 are also regulated by Rrd1p. However, transcription of these inducible GAL and non-GAL genes is not altered in the absence of Rrd1p when the steady-state is reached after long transcriptional induction. Consistently, transcription of the constitutively active genes is not changed in the Δrrd1 strain. Taken together, our results demonstrate a new function of Rrd1p in stimulation of initial rounds of transcription, but not steady-state/constitutive transcription, of both rapamycin-responsive and non-responsive genes independently of rapamycin treatment

Molecular Modeling for Calculation of Mechanical Properties of Epoxies with Moisture Ingress

Atomistic models of epoxy structures were built in order to assess the effect of crosslink degree, moisture content and temperature on the calculated properties of a typical representative generic epoxy. Each atomistic model had approximately 7000 atoms and was contained within a periodic boundary condition cell with edge lengths of about 4 nm. Four atomistic models were built with a range of crosslink degree and moisture content. Each of these structures was simulated at three temperatures: 300 K, 350 K, and 400 K. Elastic constants were calculated for these structures by monitoring the stress tensor as a function of applied strain deformations to the periodic boundary conditions. The mechanical properties showed reasonably consistent behavior with respect to these parameters. The moduli decreased with decreasing crosslink degree with increasing temperature. The moduli generally decreased with increasing moisture content, although this effect was not as consistent as that seen for temperature and crosslink degree

Multiscale Modeling of Thermal Conductivity of Polymer/Carbon Nanocomposites

Molecular dynamics simulation was used to estimate the interfacial thermal (Kapitza) resistance between nanoparticles and amorphous and crystalline polymer matrices. Bulk thermal conductivities of the nanocomposites were then estimated using an established effective medium approach. To study functionalization, oligomeric ethylene-vinyl alcohol copolymers were chemically bonded to a single wall carbon nanotube. The results, in a poly(ethylene-vinyl acetate) matrix, are similar to those obtained previously for grafted linear hydrocarbon chains. To study the effect of noncovalent functionalization, two types of polyethylene matrices. -- aligned (extended-chain crystalline) vs. amorphous (random coils) were modeled. Both matrices produced the same interfacial thermal resistance values. Finally, functionalization of edges and faces of plate-like graphite nanoparticles was found to be only modestly effective in reducing the interfacial thermal resistance and improving the composite thermal conductivit

Perceptions of an assessment literacy module to improve academic judgement – a pilot study

Expectation differences between assessors and students regarding assignment marking often results in student dissatisfaction accompanied by student complaints, indicating that despite following assignment task briefs and marking criteria, students’ desired grades were not achieved. The Assessment Literacy Module (ALM) is an online grading tool designed to promote student development of evaluative judgement. The ALM allows evaluation of sample assignments – with students being the assessor – guided by assignment marking standards that convey how assessment criteria relate to the assignment outcome; a process that often highlights discrepancies in student academic judgement. Our pilot study surveyed staff (N = 13) and students (N = 105) to gauge perceptions of the impact of the ALM on the student learning experience. Students from eight subjects in Bioscience, Science and Biomedicine, across all three undergraduate levels, indicated that they now have a better understanding of their assessment criteria (85.7%), that they found the ALM helpful in preparing their assignments (87.6%), and that they are more confident with their assessment quality (78.1%). Staff indicated that they perceived students were able to use the feedback comments on the sample assignments to better understand assignment rubrics (69.2%), and that students who used the ALM had better comprehension of assessment expectations (84.6%)

Micromechanics Modeling of Functionally Graded Interphase Regions in Carbon Nanotube-Polymer Composites

The effective elastic properties of a unidirectional carbon fiber/epoxy lamina in which the carbon fibers are coated with single-walled carbon nanotubes are modeled herein through the use of a multi-scale method involving the molecular dynamics/equivalent continuum and micromechanics methods. The specific lamina representative volume element studied consists of a carbon fiber surrounded by a region of epoxy containing a radially varying concentration of carbon nanotubes which is then embedded in the pure epoxy matrix. The variable concentration of carbon nanotubes surrounding the carbon fiber results in a functionally graded interphase region as the properties of the interphase region vary according to the carbon nanotube volume fraction. Molecular dynamics and equivalent continuum methods are used to assess the local effective properties of the carbon nanotube/epoxy comprising the interphase region. Micromechanics in the form of the Mori-Tanaka method are then applied to obtain the global effective properties of the graded interphase region wherein the carbon nanotubes are randomly oriented. Finally, the multi-layer composite cylinders micromechanics approach is used to obtain the effective lamina properties from the lamina representative volume element. It was found that even very small quantities of carbon nanotubes (0.36% of lamina by volume) coating the surface of the carbon fibers in the lamina can have a significant effect (8% increase) on the transverse properties of the lamina (E22, k23, G23 and G12) with almost no affect on the lamina properties in the fiber direction (E11 and v12)