Interfacial Shear Performance of Epoxy Adhesive Joints of Prefabricated Elements Made of Ultra-High-Performance Concrete.

Application of ultra-high-performance concrete (UHPC) in joints can improve the impact resistance, crack resistance, and durability of structures. In this paper, the direct shear performance of ultra-high-performance concrete (UHPC) adhesive joints was experimentally studied. Twenty-four direct shear loading tests of UHPC adhesive joints were carried out considering different interface types and constraint states. The failure modes and load-slip curves of different interfaces were studied. Results indicated that passive confinement could enhance the strength and ductility of the interface; the average ultimate bearing capacity of the smooth, rough, grooved, and keyway specimens with passive restraint were, respectively, increased by 11.92%, 8.91%, 11.93%, and 17.766% compared with the unrestrained ones. The passive constraint force changes with the loading and finally tends to be stable. The epoxy adhesive has high reliability as a coating for the UHPC interface. The adhesive layer is not cracked before the failure of the specimen, which is also different from the common failure mode of adhesive joints. Failure of all specimens occurred in the UHPC layer, and the convex part of the groove interface shows the UHPC matrix peeling failure; the keyway interface is the shear damage of the key-tooth root, and the rest of the keyway showed UHPC surface peeling failure. According to the failure mode, the shear capacity of UHPC keyway adhesive joints under passive restraint is mainly provided by the shear resistance of key teeth, the friction force of the joint surface, and the bonding force of the UHPC surface. The friction coefficient was determined based on the test results, and the high-precision fitting formula between the shear strength of the UHPC surface and the passive constraint force was established. According to the Mohr stress circle theory, the proposed formula for direct shear strength of UHPC bonded joints under passive constraint was established. The average ratio of the proposed UHPC adhesive joint calculation formula to the test results was 0.99, and the standard deviation was 0.027.

Tanshinone IIA induces cell death via Beclin-1-dependent autophagy in oral squamous cell carcinoma SCC-9 cell line.

Tanshinone IIA (TAN) is one of the major functional compounds of Salvia miltiorrhiza Bunge and possesses the ability to suppress the growth of multiple cancer cell types via its apoptosis- and autophagy-inducing functions. In this study, the effect of TAN therapy on the survival of oral squamous cell carcinoma (OSCC) was evaluated, and the underlying mechanism involved in the treatment was investigated. Human oral squamous cell carcinoma cell SCC-9 was used for in vitro assays and induction in an OSCC xenograft mouse model. The tumor cells were subjected to TAN administration at different concentrations. Then the apoptosis and autophagy processes in SCC-9 cells were evaluated and the activities of Beclin-1/Atg7/Atg12-Atg5 and PI3K/Akt/mTOR pathways were determined. In addition, by knocking down the expression of Beclin-1 in SCC-9 cells, the study also assessed the role of the indicator in the anti-OSCC effect of TAN. Results of in vitro assays were further validated with an OSCC xenograft mouse model. Administration of TAN-induced cell apoptosis and upregulated the expression of cleaved-caspase-3. Simultaneously, the autophagy process in SCC-9 cells was initiated by TAN, which was signaled by the formation of autophagosomes and increase in the ratio of LC3 II/LC3I. The above processes were associated with the activation of Beclin-1/Atg7/Atg12-Atg5 signaling and inhibition of PI3K/Akt/mTOR signaling. Our results also inferred a partially Beclin-1-dependent mechanism of action of TAN in OSCC cells: knockdown of the Beclin-1 blocked the effect of TAN on SCC-9 cells both in vivo and in vitro. Our study provided a preliminary explanation of the mechanism involved in TAN effect: the agent exerted its autophagy-inducing effect against OSCC in a multipronged manner, by both inducing the Beclin-1/Atg7/Atg12-Atg5 pathway and suppressing the PI3K/Akt/mTOR pathway.

The healing of alveolar bone defects with novel bio-implants composed of Ad-BMP9-transfected rDFCs and CHA scaffolds.

Cells, scaffolds, and growth factors play important roles in bone regeneration. Bone morphogenetic protein 9 (BMP9), a member of BMP family, could facilitate osteogenesis by regulating growth factors and promoting angiogenesis. Similar to other stem cells, rat dental follicle stem cells (rDFCs), the precursor cells of cementoblasts, osteoblasts and periodontal ligament cells, can self-renew and exhibit multipotential capacity. Coralline hydroxyapatite (CHA) has good biocompatibility and conductivity required for bone tissue engineering. Here, we reported that BMP9 could enhance the osteogenic differentiation of rDFCs in cell culture. Moreover, our results suggested that BMP9 acted through the Smad1/5/8 signaling pathway. We also produced a novel scaffold that encompasses bio-degradable CHA seeded with recombinant adenoviruses expressing BMP9-transfected rDFCs (Ad-BMP9-transfected rDFCs). With this implant, we achieved more alveolar bone regeneration in the alveolar bone defect compared to blank group, CHA group and rDFCs group. Our results provided a novel bio-implants composed of Ad-BMP9-transfected rDFCs and CHA scaffolds and its mechanism is regarding the activation of Smad1/5/8 signaling pathway in BMP9-induced rDFCs osteogenesis.

[Investigation of accuracy of premolar length measured by cone beam CT in vivo].

OBJECTIVE: To investigate the feasibility and accuracy of length measurement of in vivo teeth by using cone beam CT (CBCT). METHODS: Before orthodontic extraction, 109 vital premolars from 40 participants were scanned by using CBCT and reconstructed by using InVivoDental software. Buccal-lingual sectional images along the long axis of teeth were then acquired, and the crown, root, and tooth length were measured separately. After careful extraction and fixation, the corresponding length of the same tooth was measured by using a digital caliper. CBCT measurement accuracy was then verified by using physical measurements as reference. RESULTS: CBCT and the physical method did not obtain significantly different measurements of the root, crown, and tooth length of experimental teeth (P=0.790, P=0.621, P=0.657, respectively), and the measurements were found to be consistent. The 95% limits of agreement of root, crown, and tooth length were -1.10 mm to 1.13 mm, -1.00 mm to 0.96 mm, and -1.00 mm to 1.05 mm, respectively. CONCLUSION: The difference between CBCT and the physical method was not significant, and good consistency was shown. CBCT could be applied in noninvasive measurement of in vivo teeth.

[Contributions of edentulous mandibular alveolar ridge height and denture adhesive to complete denture retention].

The present paper is to investigate the relationship between height and stress-bearing area of mandibular alveolar ridge, their influence on retention of complete denture, and the effectiveness of denture adhesive (DA). Five mandibular edentulous models of different heights and a rabbit palate model were prepared in Die-Stone. Measurements were made on the heights and stress-bearing areas of mandibular alveolar ridge, the retention force of mandibular models 15 min after DA administration, and the retention force on the rabbit palate before and after adhering. All available data were analyzed statistically. Linear regression relationship was demonstrated between ridge height and bearing area, ridge height and retention force, and bearing area and retention force (P<0.01), separately. Retention force per unit area was positively related to the height and area. Retention force increased to 2.87 times postadhesive-treating. Height and stress-bearing area of mandibular alveolar ridge directly correlate with the retention of complete denture, and DA significantly improves the retention ability of complete denture.