Residue-free suspended graphene transferred by perforated template.

A residue-free transfer method for graphene is proposed in this study, especially for the fabrication of suspended structures. Using perforated polymer templates, graphene can be precisely transferred onto the specific position in the perforated target SiO2/Si substrates without the need for polymer removal and the subsequent thermal annealing process. The surface of the transferred graphene by the proposed method was analyzed and corroborated via Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy. The results of these analyses suggest that the graphene surface has no polymeric residues resulting from the transfer process. The proposed method provides a powerful approach for the transfer of 2D materials and it enables the exploitation of their suspended structures for device applications as well as the physical characterizations without worry on the effect of contaminants.

Contribution of indoor and outdoor nitrogen dioxide to indoor air quality of wayside shops.

Indoor nitrogen dioxide (NO2) concentration is an important factor for personal exposure despite the wide distribution of its sources. Exposure to NO2 may produce adverse health effects. The aims of this study were to characterize the indoor air quality of wayside shops using multiple NO2 measurements, and to estimate the contribution of outdoor NO2 sources such as vehicle emission to indoor air quality. Daily indoor and outdoor NO2 concentrations were measured for 21 consecutive days in wayside shops (5 convenience stores, 5 coffee shops, and 5 restaurants). Contributions of outdoor NO2 sources to indoor air quality were calculated with penetration factors and source strength factors by indoor mass balance model in winter and summer, respectively. Most wayside shops had significant differences in indoor and outdoor NO2 concentrations both in winter and in summer. Indoor NO2 concentrations in restaurants were twice more than those in convenience stores and coffee shops in winter. While outdoor NO2 contributions in indoor convenience stores and coffee shops were dominant, indoor NO2 contributions were dominant in restaurants. These could be explained that indoor NO2 sources such as gas range and smoking mainly affect indoor concentrations comparing to outdoor sources such as vehicle emission. The indoor mass balance model by multiple measurements suggests that quantitative contribution of outdoor air on indoor air quality might be estimated without measurements of ventilation, indoor generation and decay rate.

Prediction of endotracheal tube size using a printed three-dimensional airway model in pediatric patients with congenital heart disease: a prospective, single-center, single-group study.

BACKGROUND: To determine the correct size of endotracheal tubes (ETTs) for endotracheal intubation of pediatric patients, new methods have been investigated. Although the three-dimensional (3D) printing technology has been successful in the field of surgery, there are not many studies in the field of anesthesia. The purpose of this study was to evaluate the accuracy of a 3D airway model for prediction of the correct ETT size, and compare the results with a conventional age-based formula in pediatric patients. METHODS: Thirty-five pediatric patients under six years of age who were scheduled for congenital heart surgery were enrolled. In the pre-anesthetic period, the patient's computed tomography (CT) images were converted to Standard Triangle Language (STL) files using the 3D conversion program. A Fused Deposition Modelling (FDM) type 3D printer was used to print 3D airway models from the sub-glottis to the upper carina. ETT size was selected by inserting various sized cuffed-ETTs to a printed 3D airway model. RESULTS: The 3D method selected the correct ETT size in 21 out of 35 pediatric patients (60%), whereas the age-based formula selected the correct ETT size in 9 patients (26%). CONCLUSIONS: Prediction of the correct size of ETTs using a printed 3D airway model demonstrated better results than the age-based formula. This suggests that the selection of ETT size using a printed 3D airway model may be feasible for helping minimize re-intubation attempts and complications in patients with congenital heart disease and/or those with an abnormal range of growth and development.