Effects of post-curing duration on the mechanical properties of complex 3D printed geometrical parts.

This study aims to assess the efficacy of post-curing guidance supplied by 3D printing resin manufacturers. Current guidance applies generically to all geometries with the caveat that post-curing should be extended for 'large' or 'complex' geometries but specific guidance is not provided. Two vat-polymerisation 3D printers (Form3B, Figure 4 Standalone) were used to print test models in 6 biocompatible resins (Pro Black, Med White, Med Amber, Biomed Black, Biomed White, Biomed Amber). The test model is of a complex geometry whilst also housing ISO 527 test specimens in concentric layers. Two separate intervals of curing were applied (100%, 500% stated guidance) creating different curing treatments of the specimens throughout the model. Post processed test models were disassembled and pull testing performed on each of the specimens to assess the mechanical properties. The analysis showed that extending the curing duration had significant effects on the mechanical properties of some materials but not all. The layers of the model had a significant effect except for elongation at break for the Med Amber material. This research demonstrates that generic post-curing guidance regarding UV exposures is not sufficient to achieve homogenous material strength properties for complex geometries. Large variations in mechanical properties throughout the models suggest some material was not fully-cured. This raises a query if such materials as originally marketed as biocompatible are fully cured and therefore safe to use for medical applications involving complex geometries.

Differential Impact of Central Venous Catheters versus Arteriovenous Fistulae on Quality of Life among Irish Haemodialysis Patients.

Background: Arteriovenous fistulae (AVF) have superior clinical outcomes compared with central venous catheters (CVC) among patients undergoing hemodialysis (HD). Yet, there is increasing recognition that health-related quality of life (HRQoL) may be more important to patients than survival and that differences may exist between AVF and CVCs in this regard. This study compared HRQoL between AVF and CVC in an Irish cohort. Methods: We conducted a cross-sectional survey among prevalent patients undergoing hemodialysis (N=119) dialyzing with either an AVF or CVC at a regional program. The Short Form 36 (SF-36) and a validated Vascular Access Questionnaire (SF-VAQ) compared QoL between AVF and CVC in domains of physical functioning, social functioning, and dialysis complications. Multivariable logistic regression compared differences between groups for outcomes of physical functioning, social functioning, and dialysis complications expressed as adjusted odds ratios and 95% CI. Results: Mean age was 66.6 years; 52% were using an AVF and 48% had a CVC. Patients dialyzing with an AVF were more satisfied with their access when asked directly (6.2 versus 5.0; P<0.01). Physical functioning scores for bleeding, swelling, and bruising were significantly higher for AVF than CVC (P=0.001, P=0.001, and P<0.001, respectively). In contrast, patients with a CVC reported greater difficulties in bathing and showering than those using an AVF (4.4 versus 2.0; P<0.001), whereas patients with an AVF expressed greater concerns with physical appearances. Compared with AVF, CVC users were less likely to report difficulties in physical functioning (OR=0.35; 95% CI, 0.12 to 0.94; P=0.04) but more likely to report dialysis complications (OR=1.94; 95% CI, 0.69 to 5.87; P=0.22). Conclusions: Vascular access contributes to HRQoL in hemodialysis. CVCs are associated with fewer difficulties from bleeding and bruising but greater negative effect on social activities, including bathing and showering. Overall, patients with a CVC had lower dissatisfaction scores than patients with an AVF when all three domains were added. Innovation in vascular access design and engineering may confer benefits and improve patient comfort on HD.

Rethinking healthy eating in light of the gut microbiome.

Given the worldwide epidemic of diet-related chronic diseases, evidence-based dietary recommendations are fundamentally important for health promotion. Despite the importance of the human gut microbiota for the physiological effects of diet and chronic disease etiology, national dietary guidelines around the world are just beginning to capitalize on scientific breakthroughs in the microbiome field. In this review, we discuss contemporary nutritional recommendations from a microbiome science perspective, focusing on mechanistic evidence that established host-microbe interactions as mediators of the physiological effects of diet. We apply this knowledge to inform discussions of nutrition controversies, advance innovative dietary strategies, and propose an experimental framework that integrates the microbiome into nutrition research. The congruence of key paradigms in the nutrition and microbiome disciplines validates current recommendations in dietary guidelines, and the systematic incorporation of microbiome science into nutrition research has the potential to further improve and innovate healthy eating.

Bespoke 3D printed eye cover for teen with rhabdomyosarcoma.

BACKGROUND: We report a case of using 3D printing to create a bespoke eye cover for an 18-year-old man with left maxillary alveolar rhabdomyosarcoma. Further, the patient had proptosis causing chemosis and subsequent conjunctival abrasions. This had been managed by taping a large dressing around the eye for a number of weeks previously. METHODS: A 3D scanner was used to capture the surface topography of the patients face. The data were imported into a CAD package and used as a guide to create a bespoke eye cover. The final design was 3D printed in a biocompatible material for use by the patient. RESULTS: The scan, modelling, and printing of the bespoke cover was completed successfully in less than 72 hours. CONCLUSION: 3D printing offers a method to create bespoke solutions for patients in palliative care to meet rare and difficult clinical challenges.

Three-Dimensional Printed Devices for Health Care in Response to the Coronavirus Disease 2019: Lessons Learned to Date.

During the first surge of the coronavirus disease 2019 (COVID-19) there was a tremendous global response from three-dimensional (3D) printing communities and individuals to support local health care systems and staff. The responses involved a range of 3D printer users from amateur makers to conglomerate manufacturers creating personal protective equipment (PPE) and other supplies of which there were shortages. These new supply chains resulted from the democratization of 3D printing, open source file sharing, mass production of desktop machines, and the relatively cheap cost of 3D printers. The democratized state of 3D printing facilitated an altruistic movement of makers with ranging experience, to work alongside traditional manufacturers to make medical supplies. With the critical nature of the shortages and the sharp increase in COVID-19 infections, many standards and regulations were bypassed, and good manufacturing processes disregarded, in cases. The outcomes from this article is a set of six lessons learned from the authors perspective regarding the use of 3D printing during the initial phase of the COVID-19 pandemic. We note challenges experienced around volume manufacturing, infection control requirements of produced parts and the cleanability of devices, mechanical strength considerations, good manufacturing practices, product and intellectual property (IP) liability, and the role of involving clinical stakeholders.

A Radiopaque Nanoparticle-Based Ink Using PolyJet 3D Printing for Medical Applications.

The aim of this study was to develop a 3D printable radiopaque ink and successfully print a finished artifact. Radiopaque 3D printing would be hugely beneficial to improve the visibility of medical devices and implants, as well as allowing more realistic phantoms and calibration aids to be produced. Most 3D printing technologies are polymer based. Polymers are naturally radiolucent, allowing X-rays to pass through, showing up as faint dark gray regions on X-ray detectors, as for soft tissues. During this study, a 3D printable ultraviolet (UV) curable resin containing zirconium oxide (ZrO2) nanoparticles was developed. 5 wt.% ZrO2 was dispersed in a base resin using a high-shear mixer. Particles remained in suspension for 6-8 h at room temperature, allowing time for 3D printing. A model of a hand including radiopaque bones and a test block demonstrating a range of internal radiopaque features were successfully 3D printed. Radiopacity was demonstrated in the 3D-printed models, and there was good dispersion of ZrO2 within the resin matrix. The impregnated resin remained UV curable and viscosity was not compromised. In this study, 3D-printed radiopaque features demonstrated clear radiopacity under X-ray and microcomputed tomography imaging.