Considerable progress has been made over the last decades in thermal spray technologies, practices and applications. However, like other technologies, they have to continuously evolve to meet new problems and market requirements. This article aims to identify the current challenges limiting the evolution of these technologies and to propose research directions and priorities to meet these challenges. It was prepared on the basis of a collection of short articles written by experts in thermal spray who were asked to present a snapshot of the current state of their specific field, give their views on current challenges faced by the field and provide some guidance as to the R&D required to meet these challenges. The article is divided in three sections that deal with the emerging thermal spray processes, coating properties and function, and biomedical, electronic, aerospace and energy generation applications.

Electron beam‐physical vapor‐deposited thermal barrier coatings (TBC) are susceptible to damage due to environmental contaminants such as calcium–magnesium–aluminum–silicon oxide systems (CMAS). This paper discusses various approaches of modifying TBC for enhanced protection against CMAS attack. Methodologies were explored with various coating systems maintaining functionality as nonwetting, sacrificial, and impervious to CMAS attack. In the brief isothermal (1260°C/10 min) tests, a nearly crack‐free and reglazed Pd coating provided substantial protection from the CMAS attack. Approaches that provided some minor improvements need further optimization to better assess their viability.

Existing micronutrient deficiencies, even if only a single micronutrient, can impair immune function and increase susceptibility to infectious disease. Certain population groups are more likely to have micronutrient deficiencies, while certain disease pathologies and treatment practices also exacerbate risk, meaning these groups tend to suffer increased morbidity and mortality from infectious diseases. Optimisation of overall nutritional status, including micronutrients, can be effective in reducing incidence of infectious disease. Micronutrient deficiencies are rarely recognised but are prevalent in the UK, as well as much more widely, particularly in high-risk groups susceptible to COVID-19. Practitioners should be aware of this fact and should make it a consideration for the screening process in COVID-19, or when screening may be difficult or impractical, to ensure blanket treatment as per the best practice guidelines. Correction of established micronutrient deficiencies, or in some cases assumed suboptimal status, has the potential to help support immune function and mitigate risk of infection. The effects of and immune response to COVID-19 share common characteristics with more well-characterised severe acute respiratory infections. Correction of micronutrient deficiencies has proven effective in several infectious diseases and has been shown to promote favourable clinical outcomes. Micronutrients appear to play key roles in mediating the inflammatory response and such effects may be enhanced through correction of deficiencies. Many of those at highest risk during the COVID-19 pandemic are also populations at highest risk of micronutrient deficiencies and poorer overall nutrition. Correction of micronutrient deficiencies in established COVID-19 infection may contribute to supporting immune response to infection in those at highest risk. There is a need for further research to establish optimal public health practice and clinical intervention regimens.

We report the experience of the European Neuroblastoma Study Group (ENSG) with central nervous system (CNS) involvement of neuroblastoma. Among this series of intensively treated patients, CNS neuroblastoma was diagnosed by computerised tomography (CT) scanning, rather than by autopsy. Cranial disease occurred in 5% of ENSG patients. Of 11 patients with intracranial disease, 4 had disease in the posterior fossa, a site rarely reported previously. Furthermore, 5 cases had CNS metastases at a time when there was no detectable disease elsewhere, rather than as part of extensive relapse. The pattern of disease we observed, at least for those with parenchymal disease, is in keeping with arterial spread. Although CT scanning is the optimal modality for identifying CNS disease, 2 cases had normal head CT scans prior to the onset of CNS disease. As most patients had symptoms of raised intracranial pressure (RICP) at the time the CNS disease was diagnosed, there does not seem to be any indication for routine CT scanning of the head at diagnosis, but this should be performed as soon as any symptoms or signs appear. With patients living longer with their disease, vigilance must be maintained during follow-up.

Poor corrosion resistance is a significant limitation of magnesium alloys as structural materials. To address this problem, the objective of this study was to apply to a magnesium alloy a corrosion-resistant barrier coating that has galvanic compatibility with magnesium and a hardness value no less than that of magnesium. Aluminum coatings were applied to ZE41A-T5 Mg by the cold spray process. A custommade high-purity Al-5 wt.% Mg powder was produced by spray metal forming for the coating evaluation. In addition, coatings of commercially pure Al (99.5 wt.%), high-purity Al (99.95 wt.%), AA5356, and AA4047 were used for comparison. Coating evaluation included mechanical testing (hardness and adhesion strength) and corrosion testing (salt spray, galvanic coupling, and crevice corrosion). The Al-5% Mg powder resulted in the best overall performance, including a high hardness, 125 H v100 , and an adhesion strength, over 60 MPa, when treated for over 1000 h in a salt spray chamber and with a low galvanic current.