ABSTRACT
With ER2319 and B4C powder as feedstocks and additives, respectively, a wire arc additive manufacturing (WAAM) system based on double-pulse melting electrode inert gas shielded welding (DP-MIG) was used to fabricate single-pass multilayer 2319 aluminum alloy. The results showed that, compared with additive manufacturing component without B4C, the addition of which can effectively reduce the grain size (from 43 µm to 25 µm) of the tissue in the deposited layer area and improve its mechanical properties (from 231 MPa to 286 MPa). Meanwhile, the mechanical properties are better in the transverse than in the longitudinal direction. Moreover, the strengthening mechanism of B4C on the mechanical properties of aluminum alloy additive manufacturing mainly includes dispersion strengthening from fine and uniform B4C granular reinforcing phases and fine grain strengthening from the grain refinement of B4C. These findings shed light on the B4C induced grain refinement mechanism and improvement of WAAM 2319 Al alloy.
ABSTRACT
Energy efficiency and energy intensity are gradually gaining attention, and it is now an important proposition to reconcile financial marketization, fiscal decentralization, and regional energy intensity. Using Chinese mainland provincial panel data (except Tibet) from 2007 to 2019, this study applied the dynamic panel system generalized method of moments model, the spatial Durbin model, and the panel threshold model to investigate the mechanisms of financial marketization and fiscal decentralization on regional energy intensity. The study found that financial marketization can play a significant role in suppressing regional energy intensity, while fiscal decentralization promotes energy intensity. Meanwhile, financial marketization in one province can have a negative spatial transmission effect on energy intensity in other provinces, while fiscal decentralization in one province has a negative spatial spillover effect on energy intensity in other provinces. Based on the analysis of the moderating and threshold effects, financial marketization not only moderates the negative externality of fiscal decentralization, making it inhibit energy intensity in the opposite direction, but also gradually increases the moderating effect on fiscal decentralization as the degree of financial marketization increases, showing a nonlinear inhibiting effect on regional energy intensity.
Subject(s)
Efficiency , Politics , China , Economic Development , TibetABSTRACT
OBJECTIVES: This study aims to analyze the effectiveness of platelet-rich fibrin (PRF) in mandibular third molar extraction and provide suggestions for alleviating postoperative complications. METHODS: Pubmed, EMBASE, Web of Science, and SinoMed were searched electronically on February 2020. Randomized controlled trials focusing on PRF usage in mandibular third molar extraction were included. Reviewers assessed the risk of bias in the included literature and extracted data independently using the criteria recommended by the Cochrane Collaboration. Meta-analysis was performed using RevMan 5.3 and STATA 13.0. RESULTS: Twenty-one studies were included, comprising 991 patients who had mandibular third molar extraction. The topical application of PRF effectively reduced pain after extraction [MD=-12.06, 95%CI (-21.42, -2.71), P=0.01], attenuated post-extraction swelling [MD=-1.42, 95%CI (-2.41, -0.44), P=0.005], and promoted soft tissue hea-ling [MD=0.66, 95%CI (0.34, 0.99), P<0.000 1]. PRF significantly reduced trismus and alveolar osteitis (P<0.05). However, data could not prove whether PRF has any significant positive effect on bone healing compared with the control group (P>0.05). CONCLUSIONS: Limited clinical evidence indicates that applying PRF after mandibular third molar extraction could reduce pain, swelling, trismus and the occurrence of dry socket and promote soft tissue healing. However, the effect of PRF on bone healing requires further large-scale randomized controlled trials and unified measurement criteria.
