Fully Bottom-Up Waste-Free Growth of Ultrathin Silicon Wafer via Self-Releasing Seed Layer.

The fabrication of ultrathin silicon wafers at low cost is crucial for advancing silicon electronics toward stretchability and flexibility. However, conventional fabrication techniques are inefficient because they sacrifice a large amount of substrate material. Thus, advanced silicon electronics that have been realized in laboratories cannot move forward to commercialization. Here, a fully bottom-up technique for producing a self-releasing ultrathin silicon wafer without sacrificing any of the substrate is presented. The key to this approach is a self-organized nanogap on the substrate fabricated by plasma-assisted epitaxial growth (plasma-epi) and subsequent hydrogen annealing. The wafer thickness can be independently controlled during the bulk growth after the formation of plasma-epi seed layer. In addition, semiconductor devices are realized using the ultrathin silicon wafer. Given the high scalability of plasma-epi and its compatibility with conventional semiconductor process, the proposed bottom-up wafer fabrication process will open a new route to developing advanced silicon electronics.

Effects of a Structure-centered Cooperative Learning Safety Education Program based on Blended Learning for Elementary School Students

PURPOSE: This study was performed to determine effects of a structure-centered cooperative learning safety education program based on blended learning for elementary school students. METHODS: The study is developed in non-equivalent control group non-synchronized design. The subjects included 24 sixth grade students in the experimental group and 23 sixth grade students in the control group, respectively. To prevent diffusion of the experiment, it was carried out from May 20th to June 24th in 2015 with the control group and the other from August 26th to September 30th in 2015 with the experimental group. It was performed on experimental group after the structure-centered cooperative learning safety education program based on blended learning once a week for 6weeks. Data were analyzed by using descriptive statistics, paired t-test and independent t-test. RESULTS: After the intervention, the experimental group showed significant increases in the self-directed learning attitudes and safety behavior compared to the control group except for the academic self-efficacy. CONCLUSION: The results indicate that the structure-centered cooperative learning safety education program based on blended learning program is effective in safety education for 6th graders.

Anti-osteoporotic effects of mixed compositions of extracellular polymers isolated from Aureobasidium pullulans and Textoria morbifera in ovariectomized mice.

BACKGROUND: Extracellular polymeric substances isolated from Aureobasidium pullulans (EAP), containing specifically 13% ß-1,3/1,6-glucan, have shown various favorable bone-preserving effects. Textoria morbifera Nakai (TM) tree has been used as an ingredient in traditional medicine and tea for various pharmacological purposes. Thus, the present study was aimed to examine the synergistic anti-osteoporotic potential of mixtures containing different proportions of EAP and TM compared with that of the single formulations of each herbal extract using bilateral ovariectomized (OVX) mice, a renowned rodent model for studying human osteoporosis. METHODS: Thirty five days after bilateral-OVX surgery, 9 combinations of EAP:TM (ratios = 1:1, 1:3, 1:5, 1:7, 1:9, 3:1, 5:1, 7:1, 9:1) and single separate formulations of EAP or TM were supplied orally, once a day for 35 days at a final concentration of 200 mg/kg. Variations in body weight gains during the experimental periods, as well as femur weights, bone mineral density (BMD), bone strength (failure load), and mineral content (calcium [Ca] and inorganic phosphorus [IP]) following sacrifice were measured. Furthermore, histomorphometric and histological profile analyses of serum biochemical parameters (osteocalcin content and bone specific alkaline phosphatase [bALP] activity) were conducted following sacrifice. Femurs histomorphometric analyses were also conducted for bone resorption, structure and mass. The results for the mixed formulations of EAP:TM and separate formulations were compared with those of risedronate sodium (RES). RESULTS: The EAP:TM (3:1) formulation synergistically enhanced the anti-osteoporotic potential of individual EAP or TM formulations, possibly due to enhanced variety of the active ingredients. Furthermore, the effects of EAP:TM were comparable to those of RES (2.5 mg/kg) treatment. CONCLUSION: The results of this study suggest that, the EAP:TM (3:1) combination might act as a new pharmaceutical agent and/or health functional food substance for curing osteoporosis in menopausal women.