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Selective laser melting (SLM) has been shown to be an attractive manufacturing route for the production of α / β titanium alloys. The relationship between the SLM process parameters and the microstructure of titanium alloys has been the object of several works, but the texture formation during the SLM process has yet to be understood. In the present study, the texture formation of Ti-6Al-4V components was investigated in order to clarify which microstructural features can be tailored during the SLM process. The microstructural characterization of the as-built components was carried out using various microscopy techniques. Phase and texture analysis were carried out using backscattered electron imaging and diffraction. It was found that as-built components consist exclusively of α ′ martensitic phase precipitated from prior β columnar grains. The texture of the prior β phase was reconstructed and discussed in relation to the used SLM process parameters. It was found that the β grain solidification is influenced by the laser scan strategy and that the β phase has a strong 〈100〉 texture along its grain growth direction. The α ′ martensitic laths that originate from the parent β grains precipitate according to the Burgers orientation relationship. It was observed that α ′ laths clusters from the same β grain have a specific misorientation that minimizes the local shape strain. Texture inheritance across successive deposited layers was also observed and discussed in relation to various variant selection mechanisms.

The creation of an object by selective laser melting (SLM) occurs by melting contiguous areas of a powder bed according to a corresponding digital model. It is therefore clear that the success of this metal Additive Manufacturing (AM) technology relies on the comprehension of the events that take place during the melting and solidification of the powder bed. This study was designed to understand the generation of the laser spatter that is commonly observed during SLM and the potential effects that the spatter has on the processing of 316L stainless steel, Al-Si10-Mg, and Ti-6Al-4V. With the exception of Ti-6Al-4V, the characterization of the laser spatter revealed the presence of surface oxides enriched in the most volatile alloying elements of the materials. The study will discuss the implication of this finding on the material quality of the built parts.

An initial study of processing bioresorbable polycaprolactone (PCL) through material jetting was conducted using a Fujifilm Dimatix DMP-2830 material printer. The aim of this work was to investigate a potential solvent based method of jetting polycaprolactone. Several solvents were used to prepare a PCL solvent based ink and 1, 4-dioxane was chosen with the consideration of both solubility and safety. The morphology of PCL formed under different substrate temperatures, droplet spacings were investigated. Multi-layer PCL structures were printed and characterized. This work shows that biodegradable polycaprolactone can be processed through material jetting.

Background Following myocardial infarction (MI), therapies are recommended that reduce risk and prevent future cardiovascular events. Trends in the provision of guideline-directed medical therapies by sex, age, ethnicity and socioeconomic deprivation status may help identify opportunities to reduce inequalities in post-MI care. Methods This cohort study using linked routine healthcare data included patients with MI in South-East Scotland (1 April 2009 to 31st of July 2021). Multivariable logistic regression models with a generalized estimating equation approach were used to assess the association between each sociodemographic factor and the provision of three guideline-directed medical therapies (anti-platelet or anti-thrombotic agent, lipid-lowering therapy and renin-angiotensin system blocker) at 3-, 12-, and 18-months post-discharge. Multivariable cause-specific Cox proportional hazard models were used to evaluate medication status and risk of a composite of non-fatal myocardial infarction, non-fatal stroke, or cardiovascular death across sociodemographic subgroups. Results The study population comprised 7,926 patients (35% female, mean age 65 [SD 13] years). At 3 months, 5,393 (68%) patients were receiving all three guideline-directed medical therapies. Women (adjusted odds ratio at 3 months [aOR 0.69, 95% confidence interval 0.62 to 0.77]) and patients < 50 years (aOR 0.77, 95% confidence interval 0.65 to 0.89) and > 70 years (aOR 0.58, 95% confidence interval 0.51 to 0.65) were less likely to be receiving all three guideline-directed medical therapies at 3 months with similar observations at 12 and 18 months. No differences were observed by ethnicity and socioeconomic groups across the three time points. Patients receiving all three or one/two guideline-directed medical therapies had a lower risk of future cardiovascular events compared to those not receiving any, with this effect being consistent across all subgroups and time points. Conclusion Women, and both younger and older patients are less likely to be receiving guideline-directed medical therapy following MI, despite its benefit in reducing future cardiovascular events. Targeted strategies to increase provision of secondary prevention in these groups are needed to reduce inequalities and improve post-MI care.

Background The majority of patients with suspected acute coronary syndrome presenting to the emergency department will be discharged once myocardial infarction has been ruled out, although a proportion will have unrecognised coronary artery disease. In this setting, high-sensitivity cardiac troponin identifies those at increased risk of future cardiac events. In patients with intermediate cardiac troponin concentrations in whom myocardial infarction has been ruled out, this trial aims to investigate whether outpatient computed tomography coronary angiography (CTCA) reduces subsequent myocardial infarction or cardiac death. Methods TARGET-CTCA is a multicentre prospective randomised open label with blinded endpoint parallel group event driven trial. After myocardial infarction and clear alternative diagnoses have been ruled out, participants with intermediate cardiac troponin concentrations (5 ng/L to 99th centile upper reference limit) will be randomised 1:1 to outpatient CTCA plus standard of care or standard of care alone. The primary endpoint is myocardial infarction or cardiac death. Secondary endpoints include clinical, patient-centred, process and cost-effectiveness. Recruitment of 2270 patients will give 90% power with a two-sided P value of 0.05 to detect a 40% relative risk reduction in the primary endpoint. Follow-up will continue until 97 primary outcome events have been accrued in the standard care arm with an estimated median follow-up of 36 months. Discussion This randomised controlled trial will determine whether high-sensitivity cardiac troponin-guided CTCA can improve outcomes and reduce subsequent major adverse cardiac events in patients presenting to the emergency department who do not have myocardial infarction. Trial registration ClinicalTrials.gov Identifier: NCT03952351. Registered on May 16, 2019.

Background Patients’ pre-operative health and physical function is known to influence their post-operative outcomes. In patients with knee osteoarthritis, pharmacological and non-pharmacological options are often not optimised prior to joint replacement. This results in some patients undergoing surgery when they are not as fit as they could be. The aim of this study is to assess the feasibility and acceptability of a pre-operative package of non-operative care versus standard care prior to joint replacement. Methods/design This is a multicentre, randomised controlled feasibility trial of patients undergoing primary total knee replacement for osteoarthritis. Sixty patients will be recruited and randomised (2:1) to intervention or standard care arms. Data will be collected at baseline (before the start of the intervention), around the end of the intervention period and a minimum of 90 days after the planned date of surgery. Adherence will be reviewed each week during the intervention period (by telephone or in person). Participants will be randomised to a pre-operative package of non-operative care or standard care. The non-operative care will consist of (1) a weight-loss programme, (2) a set of exercises, (3) provision of advice on analgesia use and (4) provision of insoles. The intervention will be started as soon as possible after patients have been added to the waiting list for joint replacement surgery to take advantage of the incentive for behavioural change that this will create. The primary outcomes of this study are feasibility outcomes which will indicate whether the intervention and study protocol is feasible and acceptable and whether a full-scale effectiveness trial is warranted. The following will be measured and used to inform study feasibility: rate of recruitment, rate of retention at 90-day follow-up review after planned surgery date, and adherence to the intervention estimated through review questionnaires and weight change (for those receiving the weight-loss aspect of intervention). In addition the following information will be assessed qualitatively: analysis of qualitative interviews exploring acceptability, feasibility, adherence and possible barriers to implementing the intervention, and acceptability of the different outcome measures. Discussion The aims of the study specifically relate to testing the feasibility and acceptability of the proposed effectiveness trial intervention and the feasibility of the trial methods. This study forms the important first step in developing and assessing whether the intervention has the potential to be assessed in a future fully powered effectiveness trial. The findings will also be used to refine the design of the effectiveness trial. Trial registration ISRCTN registry, ID: ISRCTN96684272 . Registered on 18 April 2018.

After publication of our article [1] we have been notified that two of the author names have been mistakenly removed from the authorship list: Colin R. Howie and Nicholas D. Clement.After publication of our article [1] we have been notified that two of the author names have been mistakenly removed from the authorship list: Colin R. Howie and Nicholas D. Clement.

Laser powder bed fusion offers many advantages over conventional manufacturing methods, such as the integration of multiple parts that can result in significant weight-savings. The increased design freedom that layer-wise manufacture allows has also been seen to enhance component performance at little or no added cost. For such benefits to be realized, however, the material quality must first be assured. Laser ultrasonic testing is a noncontact inspection technique that has been proposed as suitable for in situ monitoring of metal additive manufacturing processes. This article explores the current capability of this technique to detect manufactured, subsurface defects in Ti-6Al-4V samples, ex situ. The results are compared with x-ray computed tomography reconstructions and focus variation microscopy. Although laser ultrasound has been used to identify material discontinuities, further work is required before this technique could be implemented in situ.

Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.

Metal additive manufacturing (AM) processes, such as selective laser melting (SLM), enable powdered metals to be formed into arbitrary three-dimensional shapes. For aluminum alloys, which are desirable in many high-value applications for their low density and good mechanical performance, SLM is regarded as challenging due to the difficulties in laser melting aluminum powders. However, a number of recent studies have demonstrated successful aluminum processing, and have gone on to explore its potential for use in advanced AM componentry. In addition to enabling the fabrication of highly complex structures, SLM produces parts with characteristically fine microstructures that yield distinct mechanical properties. Research is rapidly progressing in this field, with promising results opening up a range of possible applications across scientific and industrial sectors. This article reports on recent developments in this area of research and highlights key topics that require further attention.