Influence of molecular weight average, degree of crystallinity, and viscosity of different polyamide PA12 powder grades on the microstructures of laser sintered part

Laser Sintering (LS) allows functional parts to be produced in a wide range of powdered materials using a dedicated machine, and is thus gaining popularity within the field of rapid prototyping. It offers the user the ability to optimise part design in order to meet customer requirements with few manufacturing restrictions. A problem with LS is that sometimes the surface of the parts produced displays a texture similar to that of the skin of an orange (the so-called “orange peel” texture). The main aim of this research is to develop a methodology of controlling the input material properties of PA12 powder that will ensure consistent and good quality of the fabricated parts. Melt Flow Rate (MFR) and Gel permeation chromatography (GPC) were employed to measure the flow viscosity and molecular weight distributions of Polyamide PA12 powder grades. The experimental results proved that recycle PA12 powder with higher melt viscosity polymer has a higher entanglement with a longer molecule chain causes a higher resistance to flow which cause poor and rough surface finished on laser sintered part

STEM education from the perspective of The University of Sydney STEM Teacher Enrichment Academy

While STEM education is attracting much attention and is strongly advocated for, delivering on the promise of STEM education is still being researched (Rosicka, 2016; Margot & Kettler, 2019). The quest is on for understanding the essentials of STEM education and how to prepare teachers to capture the essence of STEM education in their professional practice. Drawing on ongoing research, the STEM Teacher Enrichment Academy, established within The University of Sydney in 2014, has developed in-service programs for teachers of both primary and secondary schools. The Academy is driven by the belief that STEM education is not a ‘fad’ and has the potential to transform pedagogy, thus motivating and enthusing students to participate more fully in the STEM disciplines, continue into senior secondary STEM subjects and beyond, ultimately addressing a shortage in STEM-related careers. With an expanding alumnus, currently at 800 teachers from 139 high schools and 370 teachers from 90 primary schools, the Academy has gathered scholarly evidence for the effectiveness and impact of its programs (Anderson, 2019; Anderson, Wilson, Tully, & Way, 2019). This presentation will share the design and structure of the Academy’s evidence-based programs as well as research on its efficacy. REFERENCES Margot, K. C. & Kettler, T. (2019). Teachers’ perception of STEM integration and education: a systematic literature review. International Journal of STEM Education, 6(2). https://doi.org/10.1186/s40594-018-0151-2 Anderson, J. (2019). Supporting STEM curriculum implementation with professional learning: The University of Sydney STEM Teacher Enrichment Academy. Journal of Physics: Conference Series. 1340 012001 Anderson, J., Wilson, K., Tully, D., & Way, J. (2019). “Can we build the wind powered car again?” Students’ and teachers’ responses to a new integrated STEM curriculum. Journal of Research in STEM Education, 5(1), 20–39. Rosicka, C. (2016). Translating STEM education research into practice. Camberwell, Vic.: Australian Council for Educational Research

Team 6: Joint Capability Metamodel-Test-Metamodel Integration with Data Farming

from Scythe : Proceedings and Bulletin of the International Data Farming Community, Issue 2 Workshop 14US adversaries are continuously seeking new ways to threaten US interests at home and abroad. In order to counter these threats, now more than ever, commanders must seek to leverage existing and emerging joint capabilities effectively in a variety of unique contexts. Achieving mission effectiveness in today's joint operational environment demands robust synergy among a wide array of mission-critical Service systems and capabilities

Towards large scale microwave treatment of ores: Part 2 - Metallurgical testing

A pilot scale microwave treatment system capable of treating 10-150t/h of material at 10-200kW was designed, constructed and commissioned in order to understand the engineering challenges of microwave-induced fracture of ores at scale and generate large metallurgical test samples of material treated at approximately 0.3-3kWh/t. It was demonstrated that exposing more of the ore to a region of high power density by improving treatment homogeneity with two single mode applicators in series yielded equivalent or better metallurgical performance with up to half the power and one third the energy requirement of that used with a single applicator. Comminution testing indicated that A*b values may be reduced by up to 7-14% and that the Bond Ball Mill Work Index may be reduced by up to 3-9% depending on the ore type under investigation. Liberation analysis of the microwave-treated ore indicated that equivalent liberation may be achievable for a grind size approximately 40-70µm coarser than untreated ore, which is in agreement with laboratory scale investigations reported in the literature at similar or higher doses. Flow sheet simulations further indicated that reduced ore competency following microwave treatment could potentially yield up to a 9% reduction in specific comminution energy (ECS) at a nominal plant grind of P₈₀190µm, or up to 24% reduction at a grind of P₈₀290µm, for a microwave energy input of 0.7-1.3kWh/t. Throughput could also be increased by up to approximately 30% depending on grind size, ore type and equipment constraints. To date, approximately 900t of material has been processed through the pilot plant, approximately 300t of which was under microwave power. Metallurgical testing has demonstrated that comminution and liberation benefits are achievable at doses lower than that previously reported in the literature, which allow high throughputs to be sustained with low installed power requirements providing a pathway to further scale-up of microwave treatment of ores

Training the Trainers in Embedding Assessment Literacy into Module Design: A Case Study of a Collaborative Transcreation Project

Translator trainers are being asked to respond in their course and module design to a variety of changing requirements, including institutional, professional and pedagogical ones. This paper proposes a way that translator trainers can respond to two sets of these new requirements. The first are those for a widening conception of translation brought about by the rapid globalisation of markets and the needs for intercultural mediators (Katan, 2016; Massey et al., 2017; Massey & Wieder, 2019). Indeed, Katan finishes the paper with the startling statement ‘There is really no question about it: if T/Is are going to survive they must make the transcreational turn’ (ibid.: 378). The second set of requirements comes from the process of articulating what attributes a graduate should possess and how these attributes are developed (Hughes, 2010). As the Higher Education Academy (HEA, 2012; see also Elkington, 2016) state, one way to ensure that the graduate skills are developed is through new assessment practices based on assessment for learning and assessment literacy. New assessment practices mean that assessment ‘does not just contribute to learning at university, but develops learning and evaluative skills essential for employment and lifelong learning’ (ibid.: 10). This paper offers translation trainers an approach to module design which can address both these sets of demands. The module is designed with a collaborative transcreation project at its core and has incorporated assessment literacy into the design. The study is supported with quantitative and qualitative data gained from a survey of participating students. By introducing the case study of our module design and linking the design to the underlying theories which informed it, the paper provides trainers with a set of concepts which could be applied to their own curricula needs in order to future proof their students in the changing employment market

Conformational spread as a mechanism for cooperativity in the bacterial flagellar switch

The bacterial flagellar switch that controls the direction of flagellar rotation during chemotaxis has a highly cooperative response. This has previously been understood in terms of the classic two-state, concerted model of allosteric regulation. Here, we used high-resolution optical microscopy to observe switching of single motors and uncover the stochastic multistate nature of the switch. Our observations are in detailed quantitative agreement with a recent general model of allosteric cooperativity that exhibits conformational spread—the stochastic growth and shrinkage of domains of adjacent subunits sharing a particular conformational state. We expect that conformational spread will be important in explaining cooperativity in other large signaling complexes