Investigation of the effects of irradiation and aging on the tribological behavior of ultra-high molecular weight polyethylene/graphene oxide composites under water lubrication.

Ultra-high molecular weight polyethylene/graphene oxide (PE-UHMW/GO) composites have demonstrated potential in artificial joint applications. The tribological behavior of irradiated PE-UHMW/GO composites under water lubrication remained unclear, which limited their application range. In this study, the PE-UHMW/GO composites were gamma irradiated at 100 KGy in a vacuum and subsequently aged at 80 °C for 21 days in air. We assessed their water absorption, and mechanical and tribological properties post-treatment. Notably, gamma irradiation markedly enhanced the mechanical and tribological performance of PE-UHMW/GO composites. Irradiated composites had a 6.11% increase in compressive strength and a 25.72% increase in yield strength compared to unirradiated composites. Additionally, under water lubrication, the irradiated composites showed improved wear resistance and a reduced friction coefficient. The irradiation enhancement can be attributed to the irradiation-induced strengthening of the interface bonding between GO and PE-UHMW. Conversely, accelerated aging led to oxidative degradation, negatively impacting these properties. Aged composites exhibited lower compressive and yield strengths, higher friction coefficients, and diminished anti-wear properties compared to the irradiated composites. The wear mechanism evolved from predominantly fatigue wear in irradiated PE-UHMW/GO to a mix of abrasive and fatigue wear post-aging. While GO and aging influenced water absorption, irradiation had a minimal effect. These insights significantly contribute to the application potential of irradiated PE-UHMW/GO composites in artificial joints.

Dosimetry of intensity-modulated radiation therapy and volumetric-modulated arc therapy techniques after modified radical mastectomy for breast cancer and hypofractionated intensity-modulated radiotherapy.

OBJECTIVE: The aim of this study was to compare the advantages and disadvantages of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with left-sided breast cancer who underwent hypofractionated IMRT after a modified radical mastectomy. MATERIALS AND METHODS: Twenty patients who required adjuvant radiotherapy after modified radical mastectomy were randomly selected, and a specified dose of 43.5 Gy/15 F was used to plan for IMRT or VMAT. Dose-volume histograms (DVHs) were utilized to evaluate the dose distribution of the planning target volumes (PTVs) and organs at risk (OARs). RESULTS: VMAT demonstrated a greater and more uniform dose distribution of PTVs and lower number of monitor units. No significant differences were found in V5 of the affected lung and heart between the two techniques (P > 0.05). The V10, V20, V30, and Dmean of the affected lung and V10, V20, V30, V40, Dmean, and Dmax of the whole heart were better in the VMAT than in the IMRT (P < 0.05). The Dmean and Dmax of the left anterior descending (LAD) branch of the coronary artery of the heart were better in the VMAT (P < 0.05), and the use of the VMAT effectively reduced the cardiopulmonary dose. A significant advantage of V30 and Dmean was also found in VMAT (P < 0.05). CONCLUSION: These findings indicate that VMAT has higher clinical significance than IMRT, because it improved the dose distribution in the target area, reduced the cardiopulmonary dose, protected the OARs (e.g. thyroid), and shortened the treatment duration.