Direct observation of terahertz topological valley transport.

Topological photonics offers the possibility of robust transport and efficiency enhancement of information processing. Terahertz (THz) devices, such as waveguides and beam splitters, are prone to reflection loss owing to their sensitivity to defects and lack of robustness against sharp corners. Thus, it is a challenge to reduce backscattering loss at THz frequencies. In this work, we constructed THz photonic topological insulators and experimentally demonstrated robust, topologically protected valley transport in THz photonic crystals. The THz valley photonic crystal (VPC) was composed of metallic cylinders situated in a triangular lattice. By tuning the relevant location of metallic cylinders in the unit cell, mirror symmetry was broken, and the degenerated states were lifted at the K and K' valleys in the band structure. Consequently, a bandgap of THz VPC was opened, and a nontrivial band structure was created. Based on the calculated band structure, THz field distributions, and valley Berry curvature, we verified the topological phase transition in such type of THz photonic crystals. Further, we showed the emergence of valley-polarized topological edge states between the topologically distinct VPCs. The angle-resolved transmittance measurements identified the bulk bandgap in the band structure of the VPC. The measured time-domain spectra demonstrated the topological transport of valley edge states between distinct VPCs and their robustness against bending and defects. Furthermore, experiments conducted on a topological multi-channel intersectional device revealed the valley-polarized characteristic of the topological edge states. This work provides a unique approach to reduce backscattering loss at the THz regime. It also demonstrates potential high-efficiency THz functional devices such as topologically protected beam splitters, low-loss waveguides, and robust delay lines.

Meta-analysis of studies on breast cancer risk and diet in Chinese women.

OBJECTIVE: A meta-analysis was carried out to summarize published data on the relationship between breast cancer and dietary factors. METHODS: Databases in Chinese (China National Knowledge Infrastructure [CNKI], China Biology Medicine [CBM], WanFang, VIP) and in English (PubMed and Web of Science) were searched for articles analyzing vegetable, fruit, soy food and fat consumption and breast cancer risk published through June 30, 2013. Random effects models were used to estimate summary odds ratios (OR) based on high versus low intake, and subgroup analysis was conducted according to region, study design, paper quality and adjustment for confounding factors to detect the potential source of heterogeneity. Every study was screened according to the inclusion criteria and exclusion criteria, evaluated in accordance with the Newcastle-Ottawa Scale. RevMan 5.2 software was used for analysis. RESULTS: Of 785 studies retrieved, 22 met inclusion criteria (13 in Chinese and 9 in English), representing 23,201 patients: 10,566 in the experimental group and 12,635 in the control group. Thirteen included studies showed vegetables consumption to be a relevant factor in breast cancer risk, OR = 0.77 (95% CI [confidence interval] 0.62-0.96). Eleven studies showed fruits consumption to be relevant, OR = 0.68 (95% CI 0.49-0.93). Significant differences were also found between those who consumed soy foods, OR = 0.68 (95% CI 0.50-0.93) and those who ate a high-fat diet, OR = 1.15 (95% CI 1.01-1.30). CONCLUSION: This analysis confirms the association between intake of vegetables, fruits, soy foods and fat and the risk of breast cancer from published sources. It's suggested that high consumption of vegetables, fruits and soy foods may reduce the risk of breast cancer, while increasing fat consumption may increase the risk.

[mRNA expression of recombinant human bone morphogenetic protein 7 in skeletal muscle satellite cells with retroviral vector-mediated rhBMP7 gene transfection].

OBJECTIVE: To detect the expression of recombinant human bone morphogenetic protein7 (rhBMP7) in skeletal muscle satellite cells (SMSCs) with rhBMP7 gene transfection mediated by retroviral vector. METHODS: rhBMP7 gene was reconstructed in retroviral vector and transferred into packaging cells PT67 via liposome reagent, with the positive cell clones selected with G418. In vitro cultured SMSCs were transfected with the virus granules secreted by PT67 cells and followed by G418 selection. Reverse transcriptase-polymerase chain reaction was utilized for analysis for rhBMP7 mRNA in the transfected cells. RESULTS: rhBMP7 retrovirus vector was successfully constructed and transferred into PT67 cells, and abundant mRNA expression of rhBMP7 was observed in the skeletal muscle satellite cells transfected with the virus and selected with G418. CONCLUSION: rhBMP7 gene can be transferred into the skeletal muscle satellite cells via retroviral vector to yield effective rhBMP7 mRNA expression.

Effect of X-ray irradiation on limb allograft rejection in adult rats.

OBJECTIVE: To establish appropriate animal models for observing the effects of X-ray irradiation on limb allograft rejection. METHODS: Wistar rats were used as donators and SD rats as recipients, the latter divided into 2 groups, namely irradiation group and non-irradiation group according to pretransplant treatment with or without X-ray radiation (5 Gy) on the part of the donators. The donor limbs were transplanted into SD rats who had their own limbs cut off, and the sciatic nerve, femoral nerve, and femoral artery and femoral vein were anastomosed in operation. After the operation, all the recipients were given benzathine benzylpenicillin, and their vital signs, together with changes of the allografts, observed. RESULTS: A total of 16 rats received transplantation that was successful in 6 rats of non-radiation group and 7 of irradiation group. The graft survival averaged 12.0+/-2.4 d in non-irradiation group and 24.7+/-8.1 d in irradiation group, showing significant difference in the lengths of survival between the 2 groups (P<0.05). CONCLUSION: The graft survival time in rats can be significantly prolonged by pretransplant irradiation of the allograft, which also help control acute rejection of the allograft.