The Facile and Efficient Fabrication of Rice Husk/poly (lactic acid) Foam Composites by Coordinated the Interface Combination and Bubble Hole Structure.

The possibility of agricultural-forestry waste (rice husks) and biodegradable plastics (poly(lactic acid)) being used to produce ecologically friendly foam composite was discussed in this work. The effects of different material parameters (the dosage of PLA-g-MAH, type and content of chemical foaming agent) on the microstructure and physical properties of composite were investigated. PLA-g-MAH promoted the chemical grafting between cellulose and PLA, and made the structure denser, thus improving the interface compatibility of the two phases and resulting in good thermal stability, high tensile strength (6.99 MPa) and bending strength (28.85 MPa) of composites. Furthermore, the properties of rice husk/PLA foam composite prepared by two kinds of foaming agents (endothermic and exothermic) were characterized. The addition of fiber limited the growth of pores, which provided better dimensional stability and narrower pore size distribution, made the interface of the composite bond tightly. And the bubble can prevent crack propagation and improve the mechanical properties of the composite. The bending strength and tensile strength of composite were 37.36 MPa and 25.32 MPa, which increased by 28.35 % and 23.27 %, respectively. Therefore, the composite prepared by using agricultural-forestry wastes and poly(lactic acid) possess acceptable mechanical properties, thermal stability and water resistance, expanding the scope of application.

Modulations of benzo[a]pyrene-induced DNA adduct, cyclin D1 and PCNA in oral tissue by 1,4-phenylenebis(methylene)selenocyanate.

Tobacco smoking is an important cause of human oral squamous cell carcinoma (SCC). Tobacco smoke contains multiple carcinogens include polycyclic aromatic hydrocarbons typified by benzo[a]pyrene (B[a]P). Surgery is the conventional treatment approach for SCC, but it remains imperfect. However, chemoprevention is a plausible strategy and we had previously demonstrated that 1,4-phenylenebis(methylene)selenocyanate (p-XSC) significantly inhibited tongue tumors-induced by the synthetic 4-nitroquinoline-N-oxide (not present in tobacco smoke). In this study, we demonstrated that p-XSC is capable of inhibiting B[a]P-DNA adduct formation, cell proliferation, cyclin D1 expression in human oral cells in vitro. In addition, we showed that dietary p-XSC inhibits B[a]P-DNA adduct formation, cell proliferation and cyclin D1 protein expression in the mouse tongue in vivo. The results of this study are encouraging to further evaluate the chemopreventive efficacy of p-XSC initially against B[a]P-induced tongue tumors in mice and ultimately in the clinic.

[Experimental research on degradation and biocompatibility of super-high-molecular-weight poly-DL-lactic acid].

OBJECTIVE: The super-high-molecular-weight poly-DL-lactic acid (PDLLA), with the molecular weight of 900 kD, is a newly emerging biomaterial and potentially used in the therapy of bone fracture because of its excellent mechanical property. However the biocompatibility of this material has not been reported so far, therefore this experiment was designed to examine whether the super-high-molecular-weight PDLLA was harmful to creatures, when it was implanted in the body of animals for a long period. METHODS: The material was prepared in small cuboids, with the size of 1.0 mm x 1.5 mm x 2.0 mm, and these blocks were implanted into the masseteric space of SD rats and, the activity of the SD-rats was monitored continuously. The animals were sacrificed in the 3rd, 6th, 9th, 12th months after the operation and, the specimens were taken out from the animals. The examination included anatomical, pathological and haematological methods. The data were analyzed with SPSS 8.0. RESULTS: The wound healed well after the operation. Super-high-molecular-weight PDLLA degraded 6 months after the implantation. In the 3rd month after the operation, a thin fiber membrane around the materials was formed. In the 6th month, the membrane was much thinner than that in the 3rd month and completely disappeared in the 9th month. The pathological examination showed that slightly inflammatory reaction appeared in the tissue around these blocks in the 3rd month, but the inflammatory reactions were gradually remitted in the following 6th, 9th and 12th months. Further, the haematological examination did not show any abnormity during the 12-month observation period. CONCLUSION: The super-high-molecular-weight PDLLA can be degrade when it is implanted into the body of creatures, which proves its good biocompatibility.