Combining SWNT and Graphene in Polymer Nanofibers: A Route to Unique Carbon Precursors for Electrochemical Capacitor Electrodes.

It is important to fabricate nanostructured architectures comprised of functional components for a wide variety of applications because precise structural control in the nanometer regime can yield unprecedented, fascinating properties. Owing to their well-defined microstructural characteristics, it has been popular to use carbon nanospecies, such as nanotubes and graphene, in fabricating nanocomposites and nanohybrids. Nevertheless, it still remains hard to control and manipulate nanospecies for specific applications, thus preventing their commercialization. Herein, first, we report unique one-dimensional nanoarchitectures with meso-/macropores, consisting of single-walled nanotubes (SWNTs), graphene, and polyacrylonitrile, in which poly(vinyl alcohol) was employed as a dispersing agent and sacrificial porogen. One-dimensional SWNTs and two-dimensional graphene pieces were combined in the confined interior space of electrospun nanofibers, which led to unique microstructural characteristics such as enhanced ordering of SWNTs, graphene pieces, and polymer chains in the nanofiber interior. Next, the SWNT/graphene-in-polymer nanofiber (SGPNF) structures were converted into carbonized products (SGCNFs) with effective porosity and tunable electrochemical properties. Similar to SGPNFs, the microstructural and electrical properties of the SGCNFs depended on the incorporated amount of SWNT and graphene. At higher SWNT content, the mesopore volume proportion and specific discharge capacitance of the SGCNFs increased by max. 63 and 598%, respectively. The SGCNFs showed strong potential as a high-performance electrode material for electrochemical capacitors (max. capacitance: nonactivated ∼390 F g-1 and activated ∼750 F g-1). Flexible, all solid-state capacitor cells based on SGCNFs were also successfully demonstrated as a model application. The SGCNFs can be further functionalized by various methods, which will impart attractive properties for extended applications.

Optimization of gearbox housing shape for agricultural UTV using structural-acoustic coupled analysis.

In this study, gearbox radiated noise was successfully reduced through housing shape optimization. First, dynamic and structural-acoustic coupled analysis models of an agricultural UTV gearbox were developed. Then, the test equipment was configured to match that of the simulation model, and a test was conducted. The analysis and test results showed errors within 0.1 dB for vibration and 0.2 dB(A) for noise, indicating that the models were reliable. The housing design was then optimized using topology optimization based on the developed structural-acoustic coupling analysis model. The sound pressure level around the housing was used as an objective function for topology optimization. The optimal distribution of materials for the housing was also derived to reduce the radiated noise. Lastly, the housing rib was designed based on the optimization result, and an improvement in the radiated noise by approximately 2.43 dB(A) was confirmed in the operation area.

Effect of sound insulation on noise reduction in an agricultural tractor cab.

Tractor cab interior noise is a risk factor that degrades operators' work performance and threatens their health; therefore, the noise must be reduced to ensure farmworkers' safety and efficiency. Cab interior noise can be classified as structure-borne noise and air-borne noise. Structure-borne noise has been extensively studied. However, although air-borne noise greatly contributes to cab interior noise, detailed frequency-domain analyses have not been performed. In this study, the components of cab interior noise were identified in the frequency domain through an order analysis, which helped improve the sound insulation of the cab and reduce the effects of air-borne noise. A test was performed while driving a tractor on a chassis dynamometer in a semi-anechoic chamber for reproducible measurement and evaluation. The A-weighted sound pressure was transformed by a fast Fourier transform algorithm, and its order was tracked by the engine speed signal. In addition, a direct path was identified by acoustic images using a sound camera. The contributions of major noise sources were identified through an order analysis. We proved that air-borne noise significantly contributes to the interior noise of tractor cabs and that improvement of the cab sound insulation is an effective noise-reduction technique.

Correction: Pine cone mold: a toolbox for fabricating unique metal/carbon nanohybrid electrocatalysts.

Correction for 'Pine cone mold: a toolbox for fabricating unique metal/carbon nanohybrid electrocatalysts' by Hyunwoo Han et al., Nanoscale, 2019, DOI: 10.1039/c9nr06794a.

Dementia Patient Segmentation Using EMR Data Visualization: A Design Study.

(1) Background: The Electronic Medical Record system, which is a digital medical record management architecture, is critical for reliable medical research. It facilitates the investigation of disease patterns and efficient treatment via collaboration with data scientists. (2) Methods: In this study, we present multidimensional visual tools for the analysis of multidimensional datasets via a combination of 3-dimensional radial coordinate visualization (3D RadVis) and many-objective optimization (e.g., Parallel Coordinates). Also, we propose a user-driven research design to facilitate visualization. We followed a design process to (1) understand the demands of domain experts, (2) define the problems based on relevant works, (3) design visualization, (4) implement visualization, and (5) enable qualitative evaluation by domain experts. (3) Results: This study provides clinical insight into dementia based on EMR data via visual analysis. Results of a case study based on questionnaires surveying daily living activities indicated that daily behaviors influenced the progression of dementia. (4) Conclusions: This study provides a visual analytical tool to support cluster segmentation. Using this tool, we segmented dementia patients into clusters and interpreted the behavioral patterns of each group. This study contributes to biomedical data interpretation based on a visual approach.

Pine cone mold: a toolbox for fabricating unique metal/carbon nanohybrid electrocatalysts.

Nature presents delicate and complex materials systems beyond those fathomable by humans, and therefore, extensive effort has been made to utilize or mimic bio-materials and bio-systems in various fields. Biomass, an inexhaustible natural materials source, can also present good opportunities for the development of unprecedented, advanced materials and processing systems. Herein, we demonstrate the use of pine cones as a biomass mold for creating new and useful metal/carbon nanohybrids (MCNHs). The inherent water-induced folding actuation of the cone scales allows the casting of an aqueous solution of a single metal precursor or a binary metal mixture into the cone mold by simply immersing the cone in the solution. The cone actively absorbs aqueous-phase metal precursors through the bract scales and the precursor ions introduced into the cone are anchored to the functional groups of the interior tissues of the cone. Subsequent heat treatment successfully led to the formation of unique MCNHs. Iron, manganese, and cobalt were employed as model metals, binary mixtures of which were also cast into the cone mold to create further versatile MCNHs. Nanoparticulate metals were formed on the carbon supports, where the size, size distribution, and crystallinity of the nanoparticles were highly dependent on the identity of the single-component precursor and the combination of precursors. Consequently, the electrochemical activity of the MCNHs also depended on which metal precursors were cast into the cone mold. The MCNH prepared from the mixture of iron and manganese precursors (MFeMnCNH) showed the best electrochemical activity. As model applications, MFeMnCNH was applied to electrode materials for electrochemical charge storage and the oxygen evolution reaction. An electrochemical capacitor cell based on the MFeMnCNH electrodes showed excellent performance with energy densities of 38.7-54.2 W h kg-1 at power densities of 16 000-160 kW kg-1. In addition, MFeMnCNH demonstrated a low overpotential of 464 mV and fast kinetics with a Tafel slope of 64.6 mV dec-1 as an electrocatalyst for the oxygen evolution reaction in 1.0 M KOH. These results substantiate that pine cones as a biomass mold show great promise for creating versatile MCNHs through further combination of various precursors.

New predictive equations for spirometric reference values and comparison with Morris equation in a Korean population.

BACKGROUND AND OBJECTIVE: The clinical importance of the differences between actual and predicted spirometric indices in non-Western populations is poorly defined. This study evaluated the differences between the spirometric values derived from Morris equation, traditionally used in South Korea, and the actual values, in the classification and detection of patients with respiratory diseases, and developed new predictive equations for the calculation of reference spirometric values for healthy Koreans. METHODS: Data derived from a subset of the population who completed the initial baseline survey of the Korean Health and Genome Study were used to develop new predictive equations for spirometric reference values, using multiple linear regression. The effects of the new equations relative to those of Morris on the detection and classification of patients with respiratory diseases were then evaluated. RESULTS: In total, 9999 people completed the baseline survey; a subgroup of 1314 met the study inclusion criteria and were used to develop the new predictive equations. Morris equation are 53.8% less accurate in detecting people with restrictive disorders and 15.8% less accurate in estimating the severity of COPD than the newly derived equations, although the differences between values derived from the traditional equations and values from the new equations were as small as 3.3-7.6%. CONCLUSIONS: The use of spirometric reference values that underestimate the actual parameters, despite the small differences, may have a significant influence on the detection of patients with restrictive disorders and the staging of COPD.