Durability test with fuel starvation using a Pt/CNF catalyst in PEMFC

In this study, a catalyst was synthesized on carbon nanofibers [CNFs] with a herringbone-type morphology. The Pt/CNF catalyst exhibited low hydrophilicity, low surface area, high dispersion, and high graphitic behavior on physical analysis. Electrodes (5 cm2) were prepared by a spray method, and the durability of the Pt/CNF was evaluated by fuel starvation. The performance was compared with a commercial catalyst before and after accelerated tests. The fuel starvation caused carbon corrosion with a reverse voltage drop. The polarization curve, EIS, and cyclic voltammetry were analyzed in order to characterize the electrochemical properties of the Pt/CNF. The performance of a membrane electrode assembly fabricated from the Pt/CNF was maintained, and the electrochemical surface area and cell resistance showed the same trend. Therefore, CNFs are expected to be a good support in polymer electrolyte membrane fuel cells

ELECTRO-MECHANICAL RESPONSE OF STRETCHABLE PDMS COMPOSITES WITH A HYBRID FILLER SYSTEM

With the technological development of wearable devices, there are increasing demands for stretchable conductor that have stable electro-mechanical performance. In this study, a stretchable PDMS composite electrodes using ternary systems of fillers consisting of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) / carbon nanotube (CNT) / silver nanowire (AgNW) is explored in a perspective of electro-mechanical response. PDMS matrix is mixed with binary fillers of CNT and PEDOT:PSS, which is followed by AgNW peeling-off process. The PDMS composite is mechanically reliable especially under tensile deformation, which showed a high rupture strain of ~102 % and tensile strength of ~2.7 MPa. In addition, the PDMS composites shows the stable electro-mechanical response, where high electrical conductivity is sustained even under stretchable conditions, showing an electrical resistance value of ~11.7 Ω/cm under 40% of strain. As a demonstration, a supercapacitor using the PDMS composites is demonstrated that shows reliable electrochemical performance

Identification and Functional Analysis of Antifungal Immune Response Genes in Drosophila

Essential aspects of the innate immune response to microbial infection appear to be conserved between insects and mammals. Although signaling pathways that activate NF-κB during innate immune responses to various microorganisms have been studied in detail, regulatory mechanisms that control other immune responses to fungal infection require further investigation. To identify new Drosophila genes involved in antifungal immune responses, we selected genes known to be differentially regulated in SL2 cells by microbial cell wall components and tested their roles in antifungal defense using mutant flies. From 130 mutant lines, sixteen mutants exhibited increased sensitivity to fungal infection. Examination of their effects on defense against various types of bacteria and fungi revealed nine genes that are involved specifically in defense against fungal infection. All of these mutants displayed defects in phagocytosis or activation of antimicrobial peptide genes following infection. In some mutants, these immune deficiencies were attributed to defects in hemocyte development and differentiation, while other mutants showed specific defects in immune signaling required for humoral or cellular immune responses. Our results identify a new class of genes involved in antifungal immune responses in Drosophila

Depth and shape from shading

Imperial Users onl

Scenario-Based Economic Impact Analysis for Bridge Closures Due to Flooding: A Case Study of North Gyeongsang Province, South Korea

Flooding has the ability to severely reduce the capacity of a transportation network. The closure of even a single bridge, which often acts as a critical link in transportation networks, can have a severe impact on the entire network. This impact can lead to significant economic costs resulting from increased travel distances for drivers. Despite the significance of these costs, however, notably few studies have been conducted to determine the societal economic cost that would be incurred due to bridge closures. One possible reason for the lack of studies investigating bridge closures due to flooding could stem from the difficultly in collecting data. To address this issue, the methodology presented in this paper uses modeling and data resources that are available for major cities in most developed countries, including those in South Korea. We evaluate the economic impact of the bridge closures using the new administrative capital of North Gyeongsang Province, South Korea as a case study. Scenarios for the closure of bridges are derived from channel surveys and hydraulic analyses. These methods are used to overcome a lack of adequate data on historical floods in the new city. Traffic is forecasted to estimate the number of road users that would be forced to take detours due to inundated bridges. Contrasting travel distances when bridges are and are not operational, economic costs incurred by bridge closures due to flooding are estimated. The results indicated that bridge closures would result in an economic cost of 1563 USD to 44,180 USD per day, depending on how many bridges are closed and how many people are living in the new city. The estimates from this study will act as guidelines for identifying cost-effective mitigation and preparedness strategies aimed at reducing the frequency and impact of bridge closures due to flooding

Mini Review of Reliable Fabrication of Electrode under Stretching for Supercapacitor Application

Currently, there is an increasing demand for portable and wearable electronics. This has necessitated the development of stretchable energy storage devices, while simultaneously maintaining performance. Hence, the electrodes and electrolyte materials used in stretchable supercapacitors should be robust under severe mechanical deformation. Polymers are widely used in the fabrication of stretchable supercapacitors. It is not only crucial to choose good polymer candidates with inherent advantages, but it is also important to design suitable polymer materials for both electrodes and electrolytes. This mini-review explains the concept of stretchable supercapacitors, the theoretical background of polymer-based electrodes for supercapacitors, and the fabrication strategies of stretchable electrodes for supercapacitors. Finally, we present the drawbacks and areas that still need to be developed

Reduction of Cav1.3 channels in dorsal hippocampus impairs the development of dentate gyrus newborn neurons and hippocampal-dependent memory tasks

Cav1.3 has been suggested to mediate hippocampal neurogenesis of adult mice and contribute to hippocampal-dependent learning and memory processes. However, the mechanism of Cav1.3 contribution in these processes is unclear. Here, roles of Cav1.3 of mouse dorsal hippocampus during newborn cell development were examined. We find that knockout (KO) of Cav1.3 resulted in the reduction of survival of newborn neurons at 28 days old after mitosis. The retroviral eGFP expression showed that both dendritic complexity and the number and length of mossy fiber bouton (MFB) filopodia of newborn neurons at 14 days old were significantly reduced in KO mice. Both contextual fear conditioning (CFC) and object-location recognition tasks were impaired in recent (1 day) memory test while passive avoidance task was impaired only in remote ( 20 days) memory in KO mice. Results using adeno-associated virus (AAV)-mediated Cav1.3 knock-down (KD) or retrovirus-mediated KD in dorsal hippocampal DG area showed that the recent memory of CFC was impaired in both KD mice but the remote memory was impaired only in AAV KD mice, suggesting that Cav1.3 of mature neurons play important roles in both recent and remote CFC memory while Cav1.3 in newborn neurons is selectively involved in the recent CFC memory process. Meanwhile, AAV KD of Cav1.3 in ventral hippocampal area has no effect on the recent CFC memory. In conclusion, the results suggest that Cav1.3 in newborn neurons of dorsal hippocampus is involved in the survival of newborn neurons while mediating developments of dendritic and axonal processes of newborn cells and plays a role in the memory process differentially depending on the stage of maturation and the type of learning task. © 2017 Kim et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Scenario-Based Economic Impact Analysis for Bridge Closures Due to Flooding: A Case Study of North Gyeongsang Province, South Korea

Flooding has the ability to severely reduce the capacity of a transportation network. The closure of even a single bridge, which often acts as a critical link in transportation networks, can have a severe impact on the entire network. This impact can lead to significant economic costs resulting from increased travel distances for drivers. Despite the significance of these costs, however, notably few studies have been conducted to determine the societal economic cost that would be incurred due to bridge closures. One possible reason for the lack of studies investigating bridge closures due to flooding could stem from the difficultly in collecting data. To address this issue, the methodology presented in this paper uses modeling and data resources that are available for major cities in most developed countries, including those in South Korea. We evaluate the economic impact of the bridge closures using the new administrative capital of North Gyeongsang Province, South Korea as a case study. Scenarios for the closure of bridges are derived from channel surveys and hydraulic analyses. These methods are used to overcome a lack of adequate data on historical floods in the new city. Traffic is forecasted to estimate the number of road users that would be forced to take detours due to inundated bridges. Contrasting travel distances when bridges are and are not operational, economic costs incurred by bridge closures due to flooding are estimated. The results indicated that bridge closures would result in an economic cost of 1563 USD to 44,180 USD per day, depending on how many bridges are closed and how many people are living in the new city. The estimates from this study will act as guidelines for identifying cost-effective mitigation and preparedness strategies aimed at reducing the frequency and impact of bridge closures due to flooding

Mini Review of Technological Trends of Flexible Supercapacitors Using Carbon Nanotubes

With the technological advances in wearable and portable electronic devices, the demands for associated technologies including flexible energy storage devices increase. Among many types of energy storage devices, flexible supercapacitors (FSCs) are highly attractive in comparison with others as they exhibit high power density, high storage density, and mechanical stability. In particular, carbon nanotubes (CNTs) are being widely used as the electrode materials for FSCs, owing to their mechanical strength and outstanding electrical performance. Herein, we classified CNT-based FSCs according to the structural types of CNTs and the materials incorporated. The unique structures and properties of the three types of CNTs (single-walled CNTs (SWCNT), double-walled CNTs (DWCNT), and multi-walled CNTs (MWCNT)) are compared and the mechanisms of FSCs are discussed. Finally, a summary of the overall electrochemical properties and current development of the reported FSC electrodes based on SWCNT, DWCNT, and MWCNT are presented thoroughly

Heat Dissipation of Open-Cell-Type Aluminum Foams Manufactured by Replication-Casting Process

Open-cell-type aluminum foam demonstrates excellent heat dissipation owing to interconnected pores. In this study, open-cell-type aluminum foams with various pore sizes and porosities were fabricated using the replication-casting process, which is a relatively simple process. The porosity of the manufactured foams ranged from approximately 55% to 62%. To assess the heat dissipation of the manufactured foams, an air-cooling system was designed. The device could pass a controlled amount of air through the connected pores, simultaneously measuring pressure drop ∆P and temperature changes. It was confirmed that the open-cell-type aluminum foams exhibited a very high cooling rate in the initial cooling phase, and the thermal behavior is influenced by structural characteristics. At a porosity of 62%, the initial maximum cooling rate was measured to be 1.41 ℃/s for a pore size of 0.7~1.0 mm, and it was observed to significantly increase to 3.82 ℃/s for a pore size of 2.8~3.4 mm. Furthermore, for the same pore size, an increase in porosity resulted in an increase in the initial cooling rate. Lager pore sizes and higher porosities led to lower pressure drop ∆P and improved airflow, enhancing the cooling efficiency of open-cell-type aluminum foams