Alumina Ceramics for Armor Protection via 3D Printing Using Different Monomers.

Alumina ceramic is an ideal candidate for armor protection, but it is limited by the difficult molding or machining process. Three-dimensional printing imparts a superior geometric flexibility and shows good potential in the preparation of ceramics for armor protection. In this work, alumina ceramics were manufactured via 3D printing, and the effects of different monomers on the photosensitive slurry and sintered ceramics were investigated. The photosensitive slurries using dipropylene glycol diacrylate (DPGDA) as a monomer displayed the optimal curing performance, with a low viscosity, small volume shrinkage and low critical exposure energy, and each of the above properties was conducive to a good curing performance in 3D printing, making it a suitable formula for 3D-printed ceramic materials. In the 3D-printed ceramics with DPGDA as a monomer, a dense and uniform microstructure was exhibited after sintering. In comparison, the sample with trimethylolpropane triacrylate (TMPTA) showed an anisotropic microstructure with interlayer gaps and a porosity of about 9.8%. Attributed to the dense uniform microstructure, the sample with DPGDA exhibited superior properties, including a relative density of 97.5 ± 0.5%, a Vickers hardness of 19.4 ± 0.8 GPa, a fracture toughness of 2.6 ± 0.27 MPa·m1/2, a bending strength of 690 ± 54 MPa, and a dynamic strength of 3.7 ± 0.6 GPa at a strain rate of 1200 s-1.

Enhanced Mechanical Properties of Al2O3 Nanoceramics via Low Temperature Spark Plasma Sintering of Amorphous Powders.

In this work, Al2O3 nanoceramics were prepared by spark plasma sintering of amorphous powders and polycrystalline powders with similar particle sizes. Effective comparisons of sintering processes and ultimate products depending on starting powder conditions were explored. To ensure near-full density higher than 98% of the Al2O3 nanoceramics, the threshold temperature in SPS is 1450 °C for polycrystalline Al2O3 powders and 1300 °C for amorphous powders. The low SPS temperature for amorphous powders is attributed to the metastable state with high free energy of amorphous powders. The Al2O3 nanoceramics prepared by amorphous powders display a mean grain size of 170 nm, and superior mechanical properties, including high bending strength of 870 MPa, Vickers hardness of 20.5 GPa and fracture toughness of 4.3 MPa∙m1/2. Furthermore, the Al2O3 nanoceramics prepared by amorphous powders showed a larger dynamic strength and dynamic strain. The toughening mechanism with predominant transgranular fracture is explained based on the separation of quasi-boundaries.

Increased expression of microRNA-93 correlates with progression and prognosis of prostate cancer.

MicroRNA-93 (miR-93) has been found to be up-regulated in multiple malignancies. miR-93 might promote the proliferation and invasion of prostate cancer cell. In the present study, we aimed to investigate the expression level of miR-93 in prostate cancer tissues and its clinical and prognostic value in patients with prostate cancer.A total of 103 paired prostate cancer tissues and adjacent normal tissues were obtained from male patients who underwent surgical treatment in the department of urology, Huizhou Third People's Hospital, Guangzhou Medical University between July 2014 and March 2018. The correlation between prostate cancer characteristics and miR-93 expression was examined by chi-square test. Patient survival was evaluated using the Kaplan-Meier method and compared using log-rank test. Univariate and multivariate Cox regression analyses were performed for survival data.Compared to noncancerous prostate tissues, the expression levels of miR-93 in prostate cancer tissues were significantly increased (P < .001). High level of miR-93 expression was significantly correlated with Gleason score (P = .018), lymph node involvement (P = .026), bone metastasis (P < .001), and Tumor Node Metastasis (TNM) stage (P < .001). The 5-year overall survival rate in the high expression group was lower than that in the low expression group (log-rank test, P = .031). Multivariate Cox regression analysis showed that miR-93 expression level (HR = 2.181, 95% CI: 1.092-6.829, P = .028) was an independent factor in predicting the overall survival of prostate cancer patients.The present study demonstrated that increased expression of miR-93 correlates with progression and prognosis of prostate cancer. These fndings suggest miR-93 may serve as a novel target for prostate cancer prognosis and therapy.