RESUMEN
Shaping hard and brittle materials, e.g. cermets, at micrometer resolution has long been known challenging for both mechanical machining and high energy beam based additive manufacturing. Digital light processing (DLP), which features great printing quality and decent precision, unfortunately lacks capability to deal with the popular slurry-typed cermet precursor due to the tremendous optical absorption by its particles. Here, an innovative protocol based on a versatile collapsable matrix is devised to allow high-precision printing of WC-Co cermets on DLP platform. By tuning the external environment, this matrix attenuates composite powders to facilitate photopolymerization at the printing stage, and shrinks to condense green parts prior to thermal sintering. The as-obtained samples by collapsable matrix assisted DLP can reach a relative density of ≈90%, a record-breaking resolution of ≈10 µm, and a microhardness of up to 14.5 GPa. Complex delicate structures, including school emblem, honeycomb, and micro-drill can be directly fabricated, which has never been achieved before. Impressively, the as-obtained micro-drill is able to be directly used in drilling tasks. The above strategy represents a great progress in DLP by enabling shaping strong light attenuating materials at high resolution. Such advantages are ideal for the next generation ceramic-metal composite additive manufacturing.
RESUMEN
Owing to high water content and homogeneous texture, conventional hydrogels hardly reach satisfactory mechanical performance. Tensile-resistant groups and structural heterogeneity are employed to fabricate tough hydrogels. However, those techniques significantly increase the complexity and cost of material synthesis, and have only limited applicability. Here, it is shown that ultra-tough hydrogels can be obtained via a unique hierarchical architecture composed of chemically coupled self-assembly units. The associative energy dissipation among them may be rationally engineered to yield libraries of tough gels with self-healing capability. Tunable tensile strength, fracture strain, and toughness of up to 19.6 MPa, 20 000%, and 135.7 MJ cmâ»3 are achieved, all of which exceed the best known records. The results demonstrate a universal strategy to prepare desired ultra-tough hydrogels in predictable and controllable manners.
RESUMEN
OBJECTIVE: To observe the regulatory effect of 6-Shogaol on Notch signal pathway in colonic epithelial cells of mice with ulcerative colitis. METHODS: Forty Kunming mice were randomly divided into normal group (n=10) and model group (n=30). The model of ulcerative colitis was induced by free drinking of 2% dextran sulfate sodium salt(DSS). After 15 days, the mice were divided into model group, 6-gingerenol group and positive control group with 10 mice in each group. Normal group and model group were treated with normal saline, 6-gingerenol group was treated with 6-Shogaol 100 mg/(kg·d), positive control group was treated with sulfasalazine 100 mg/(kg·d), for 20 days. The histopathological changes of colon were observed, and the expressions of Hes-1 and Math-1protein in colonic epithelial cells were detected by immunofluorescence double labeling method. The expressions of Notch-1, Hes-1 and Math-1 mRNA in colonic epithelial tissue were detected by RT-PCR. The expressions of Notch-1, Hes-1 and Math-1 protein in colonic epithelial tissue was detected by Western blot. RESULTS: Compared with the normal group, the expression of Notch-1 and Hes-1 protein and the relative expression of mRNA in colonic epithelium of model group were significantly increased (Pï¼0.01), while the relative expressions of Math-1 mRNA and protein were decreased significantly (Pï¼0.01). Compared with the model group, the expressions of Notch-1 and Hes-1 protein and the relative expression of mRNA in colonic epithelium of 6-Shogaol group and sulfasalazine group were decreased significantly(Pï¼0.01), while the relative expressions of Math-1 mRNA and protein were increased significantly(Pï¼0.01). CONCLUSION: 6-Shogaol can inhibit the over activation of Notch pathway and regulate the balance of differentiation between colonic epithelialabsorptive cell line and secretory cell line and repair damaged mucosal tissue.