Exhaust gas analysis and formation mechanism of SiC nanowires synthesized by thermal evaporation method

Silicon carbide nanowires (SiCNWs) are a set of promising reinforcement materials due to their superior properties. However, formation mechanism of the SiCNWs synthesized by the thermal evaporation method without metal catalyst is still unclear. To understand the formation mechanism, SiCNWs were synthesized by the thermal evaporation method at 1350 °C using a pre-oxidized Si powder and CH4 gas as precursors. SiCNWs obtained by this method were β-SiC/SiO2 core–shell nanowires with average diameter about 55 nm and with a length up to 1 mm. The exhaust gases during the SiCNWs synthesis process were examined by gas chromatography and the photographs of growth activity of SiCNWs inside the furnace were captured. CO gas was detected during the active formation of SiCNWs. It was clarified that CO gas was one of the byproducts from SiCNWs synthesis process, and the formation reaction of SiCNWs should be 3SiO(g) + 3C(s) → 2SiC(s) + SiO2(s) + CO(g). The formation of SiCNWs was discussed based on the oxide-assisted-growth mechanism

Engineering thick cell sheets by electrochemical desorption of oligopeptides on membrane substrates

We developed a gold-coated membrane substrate modified with an oligopeptide layer that can be used to grow and subsequently detach a thick cell sheet through an electrochemical reaction. The oligopeptide CCRRGDWLC was designed to contain a cell adhesive domain (RGD) in the center and cysteine residues at both terminals. Cysteine contains a thiol group that forms a gold–thiolate bond on a gold surface. Cells attached to gold-coated membrane substrates via the oligopeptide layer were readily and noninvasively detached by applying a negative electrical potential to cleave the gold–thiolate bond. Because of the effective oxygen supply, fibroblasts vigorously grew on the membrane substrate and the thickness of the cell sheets was ∼60 μm at 14 days of culture, which was 2.9-fold greater than that of cells grown on a conventional culture dish. The cell sheets were detached after 7 min of electrical potential application. Using this approach, five layers of cell sheets were stacked sequentially with thicknesses reaching >200 μm. This approach was also beneficial for rapidly and readily transplanting cell sheets. Grafted cell sheets secreted collagen and remained at the transplanted site for at least 2 months after transplantation. This simple electrochemical cell sheet engineering technology is a promising tool for tissue engineering and regenerative medicine applications

〈Originals〉Swallowing function in patients who underwent after subtotal glossectomy and reconstruction with a rectus abdominis musculocutaneous flap

[Abstract]Purpose: Swallowing function was evaluated 3 years after surgery in three tongue cancer patients who underwent bilateral total neck dissection and subtotal glossectomy with reconstruction using a rectus abdominis musculocutaneous flap. Materials and Methods: The morphology of the flap and swallowing function were evaluated. Swallowing function was assessed by video fluorography with a 10 ml test diet. The items for evaluation of swallowing were: (1) holding the test diet in the oral cavity, (2) epiglottis turnover, (3) aspiration, (4) hyoid bone movement, and (5) maximum width of the esophageal entrance. Results: With regard to flap morphology, two patients had a protuberant flap and one had a semi-protuberant flap. One patient was able to hold the test diet in the oral cavity, while slight flow of the test diet into the pharynx was observed in the other 2 patients. Epiglottis turnover was good in one patient, but was insufficient in two patients. Aspiration was not observed in any of the patients. The hyoid bone moved forward and upward in all three patients. The maximum width of the esophageal entrance was good in all patients. Conclusions: Elevation of the hyoid bone was demonstrated in all three patients, even though almost all of the bilateral suprahyoid muscles had been resected with the exception of stylohyoid. For good postoperative swallowing function and hyoid bone movement after subtotal glossectomy, it is necessary to perform reconstruction with a flap that has sufficient volume and to retain the bilateral stylohyoid muscles

〈Case Reports〉Clinical study of six patients with foreign bodies into maxillary sinus

[Abstract]Six patients with iatrogenic and noniatrogenic foreign bodies in the maxillary sinus are presented. Four patients had iatrogenic foreign bodies, including a dental implant, a maxillary wisdom tooth, a maxillary wisdom tooth root and a dental root canal filler. The other two patients with non-iatrogenic foreign bodies fractured an interdental brush while cleaning their teeth and it entered the maxillary sinus. For surgical extraction of foreign bodies, the intra-oral and trans-nasal approaches were performed in 5 patients and 1 patient, respectively. A total of 130 Japanese patients with foreign bodies in the maxillary sinus from 1981 to 2015 were reviewed. The rate of iatrogenic and non-iatrogenic cases were 97.7%, and 2.3% respectively. With regard to dental foreign bodies, all of the reported patients had a tooth root in the maxillary sinus, and our patients with displacement of an entire tooth(including the crown and root)in the maxillary sinus was rare. It is necessary for dentists to perform detailed preoperative evaluation and careful extraction of maxillary wisdom teeth. There were 3 patients with broken interdental brush in the maxillary sinus. The common point of those 3 patients and our 2 patients was that relatively new interdental brushes were used, and been inserted into the periodontal pocket, which is an incorrect cleaning method. It is important for dentists and dental hygienists to provide instructions on the appropriate method of cleaning the teeth with interdental brush in order to prevent fracture and entry of the broken brush into the maxillary sinus