Selective Laser Melting Fabrication of the Nickel Base Superalloy CMSX486: Optimisation of Process Parameters using Image Analysis and Statistical Methods

Purpose – The purpose of this paper is to optimise the selective laser melting (SLM) process parameters for CMSX486 to produce a “void free” (fully consolidated) material, whilst reducing the cracking density to a minimum providing the best possible fabricated material for further post-processing. SLM of high temperature nickel base superalloys has had limited success due to the susceptibly of the material to solidification and reheat cracking. Design/methodology/approach – Samples of CMSX486 were fabricated by SLM. Statistical design of experiments (DOE) using the response surface method was used to generate an experimental design and investigate the influence of the key process parameters (laser power, scan speed, scan spacing and island size). A stereological technique was used to quantify the internal defects within the material, providing two measured responses: cracking density and void per cent. Findings – The analysis of variance (ANOVA) was used to determine the most significant process parameters and showed that laser power, scan speed and the interaction between the two are significant parameters when considering the cracking density. Laser power, scan speed, scan spacing and the interaction between power and speed, and speed and spacing were the significant factors when considering void per cent. The optimum setting of the process parameters that lead to minimum cracking density and void per cent was obtained. It was shown that the nominal energy density can be used to identify a threshold for the elimination of large voids; however, it does not correlate well to the formation of cracks within the material. To validate the statistical approach, samples were produced using the predicted optimum parameters in an attempt to validate the response surface model. The model showed good prediction of the void per cent; however, the cracking results showed a greater deviation from the predicted value. Originality/value – This is the first ever study on SLM of CMSX486. The paper shows that provided that the process parameters are optimised, SLM has the potential to provide a low-cost route for the small batch production of high temperature aerospace components. </jats:sec

Regulation of the Base Excision Repair Pathway by Ubiquitination

Genome integrity is under constant threat from cellular reactive oxygen species generated by endogenous and exogenous mutagens. The base excision repair (BER) pathway consequently plays a crucial role in the repair of DNA base damage, sites of base loss and DNA single strand breaks that can cause genome instability and ultimately the development of human diseases, including premature ageing, neurodegenerative disorders and cancer. Proteins within the base excision repair pathway are increasingly being found to be regulated and controlled by post-translational modifications, and indeed ubiquitination performs a key role in the maintenance of repair protein levels but may also impact on protein activity and cellular localisation. This process is therefore important in maintaining an efficient cellular DNA damage response, and if not accurately controlled, can cause DNA damage accumulation and promote mutagenesis and genomic instability. In this chapter, we will present up-to-date information on the evidence of ubiquitination of base excision repair proteins, the enzymes involved and the molecular and cellular consequences of this process

Kinematic repeatability analyses of multi-segment foot motion in university-level ballet dancers

Background: Dancers are susceptible to overuse foot and ankle injuries, however there is a lack biomechanical studies examining foot mechanics to explain the causality of these injuries. The purpose of this study was to determine the intra and inter-assessor repeatability of a modified Rizzoli Foot Model (RFM) for ballet dancers. Methods: Six university-level ballet dancers performed the following trials in randomized order, natural stance, turnout plié and stance, and two dynamic trials; turnout rise and flex-point-flex movement. A twelve-camera motion capture system were used to track fourteen reflective markers and one triad on the following segments: shank, entire foot, hindfoot, midfoot, forefoot and hallux. A repeated-measure design was used with each participant undergoing four data collection sessions; i.e. two sessions were conducted by each researcher over two consecutive days. Variability of the 3D segment rotations and planar angles were determined using intra-class correlation coefficients (ICC) for the intra and inter-assessor repeatability. Results: Intra and inter-assessor reliability demonstrated excellent (ICC ≥ 0.75) reliability for 1st metatarsophalangeal joint sagittal plane measurements. Intra-assessor variability demonstrated excellent (ICC ≥ 0.75) reliability in the sagittal plane and frontal planes for all the discrete static variables, except the midfoot-forefoot articulation which was in the sagittal and transverse planes. Whereas the inter-assessor variability revealed fair to good repeatability (0.5 ≤ ICC \u3c 0.75). The trend towards a lower inter-assessor repeatability indicates the lack of training of the marker placement protocol. A similar trend was found in the repeatability in the dynamic trials. Intra and inter-assessor reliability demonstrated excellent (ICC ≥ 0.75) reliability for 1st metatarsophalangeal joint sagittal plane measurements. Intra-assessor variability demonstrated excellent (ICC ≥ 0.75) reliability in the sagittal and frontal planes for all the discrete static variables, except the midfoot-forefoot articulation which was in the sagittal and transverse planes. Inter-assessor repeatability revealed large variability from poor to excellent (0.5 \u3e ICC ≥ 0.75) repeatability for the 3D segmental rotations. Conclusion: Three-dimensional multi-segment foot models have the potential to be reliably used in dance screenings to ascertain whether technical errors and/or biomechanical abnormalities are the cause of a dancers’ lower limb overuse injury. However, research laboratories should develop good marker placement protocol to endeavour to produce repeatable between assessor results.https://ro.ecu.edu.au/ecuposters/1024/thumbnail.jp

An analysis of the foot in turnout using a dance specific 3D multi-segment foot model

Introduction: Recent three-dimensional (3D) kinematic research has revealed foot abduction is the strongest predictor of standing functional and forced turnout postures. However, it is still unknown how the internal foot joints enable a large degree of foot abduction in turnout. The primary purpose of this study was to use a dance specific multi-segment foot model to determine the lower leg and foot contributions to turnout that female university-level ballets use to accentuate their turnout. Methods: Eighteen female dance students (mean age, 18.8 ± 1.6 years) volunteered for this study. Retro-reflective markers were attached to the dancers\u27 dominant foot. Each dancer performed three repetitions of functional turnout, forced turnout and ten consecutive sautés in first position. Repeated measures ANOVA with Bonferroni adjustments for the multiple comparisons were used to determine the kinematic adjustments, hindfoot eversion, midfoot and forefoot abduction, navicular drop (i.e. lowering of the medial longitudinal arch) and first metatarsophalangeal joint abduction between natural double leg up-right posture and the first position conditions. Results: Hindfoot eversion (4.6°, p \u3c 0.001) and midfoot abduction (2.8°, p \u3c 0.001) significantly increased in functional turnout compared to the natural double leg up-right posture. Thirteen dancers demonstrated increased first metatarsophalangeal joint (MTPJ) abduction in forced turnout, however no statistically significant increase was found. Navicular drop during sautés in first position significantly increased by 11 mm (p \u3c 0.001) compared to the natural double leg up-right posture. Conclusion: Our findings suggest dancers do pronate, via hindfoot eversion and midfoot abduction in both functional and forced turnout, however, no immediate association was found between forced turnout and first MTPJ abduction. Foot pronation does play a role in achieving turnout. Further prospective research on in situ measures of the lower limb in turnout and injury surveillance is required to improve our understanding of the normal and abnormal dance biomechanics. © 2019 The Author(s)

Personality Measures Link Slower Binocular Rivalry Switch Rates to Higher Levels of Self-Discipline

In this paper we investigated the relation between personality and the rate of perceptual alternations during binocular rivalry. Studies have demonstrated that slower rivalry alternations are associated with a range of clinical conditions. It is less clear whether rivalry dynamics similarly co-vary with individual differences in psychological traits seen across non-clinical population. We assessed rivalry rates in a non-clinical population (n = 149) and found slower rivalry alternations were positively related r(149) = 0.20, p = 0.01 to industriousness, a trait characterized by a high level of self-discipline using the Big Five Aspect Scales (BFAS). Switch rates were also negatively related r(149) = -0.20, p = 0.01 to cognitive disorganization, a schizotypy trait capturing schizophrenia-like symptoms of disorganization using the Oxford-Liverpool Inventory of feelings and Experiences (O-LIFE). Furthermore, we showed that that these relations with personality were unaffected by the inclusion or exclusion of mixed percept in the response analysis. Together these results are relevant to theoretical models of rivalry investigating individual differences in rivalry temporal dynamics and they may reduce concerns about the impact of task compliance in clinical research using rivalry as a potential diagnostic tool

Novel hybrid manufacturing process of CM247LC and multi-material blisks

The study on CM247LC used the traditional approach for Near-Netshape Hot Isostatic Pressing (NNSHIP) with sacrificial low carbon steel tooling, which was built using Selective Laser Melting (SLM), to produce a shaped CM247LC blisk. The assessment of the microstructure focused on both the exterior components in order to determine the depth of the Fe-diffusion layer and on the interior microstructure. Samples were extracted from the Hot Isostatic Pressed (HIPped) components for tensile testing at both room and elevated temperatures. The components were scanned to assess the geometrical shrinkages due to Hot Isostatic Pressing (HIPping). An oversized blisk was also produced based on the measurements as a demonstrator component. In addition, a further study was carried out on a novel idea that used a solid IN718 disk in the centre of the blisk to create a multi-material component

Exploring the relationship between mindset and psychological factors linked to doping

Mindset refers to the way in which one attributes his or her abilities and traits as either ‘fixed’ (e.g., immutable), ‘growth’ (e.g., highly malleable), or somewhere in between. It is possible that mindset may be related to psychological factors linked to doping – such as doping moral disengagement (MD) and doping self-regulatory efficacy (SRE) – though no research as yet has confirmed this. In the present study, 322 student-athletes completed a questionnaire pack measuring mindset and various psychological factors linked to doping. Structural equation modeling provided strong support for all study hypotheses. Specifically, we established: (a) mindset positively predicted doping SRE, (b) mindset negatively predicted doping MD, (c) doping MD positively predicted susceptibility to intentional and inadvertent doping, (d) doping MD negatively predicted anticipated guilt, (e) anticipated guilt negatively predicted susceptibility to intentional and inadvertent doping. In addition, significant negative correlations were found between MSA and doping moral disengagement (r = -.19, p &lt; .01), MSA and susceptibility to inadvertent doping (r = -.11, p &lt; .01), MMC and moral disengagement (r = -.12, p &lt; .05), and MMC and susceptibility to inadvertent doping (r = -.13, p &lt; .05). A significant positive correlation was found between MSA and doping SRE (r = .23, p &lt; .01). Implications of the findings include the potential for early identification of athletes at risk of doping based on their mindset. Future research should look to explore the effectiveness of mindset interventions on reducing transgressive doping attitudes and behaviours

Using SamplePoint to Determine Vegetation Percent Cover in a Sagebrush Steppe Ecosystem

Multi-temporal satellite imagery can be used to map species level vegetation across large areas. This is due to the fact that plants have unique spectral signatures in the electromagnetic spectrum and satellite imagery collects data from specific areas of the electromagnetic spectrum in different wavelengths (or bands) and over different time periods. However, in order to use satellite imagery to map vegetation using spectral signatures, vegetation information from the ground is needed to “train and validate” the satellite imagery. One of the ways of collecting vegetation information is using signature plots. Signature plots are high resolution local images collected with a digital camera of ground vegetation in a specific environment. These signature plots can then be analyzed using a computer software called SamplePoint in order to produce a percent vegetation cover for different vegetation species for the area which the camera covers. The percent vegetation cover information can then be used to train and validate the satellite imagery. SamplePoint offers a unique way to expand small physical observations to large landscapes