SrCe0.7Zr0.2Eu0.1O3-based hydrogen transport water gas shift reactor

Proton-transport-membrane water gas shift (WGS) reactors, based on thin dense SrCe_0.7Zr_0.2Eu_0.1O_3−δ membranes on tubular Ni–SrCe_0.8Zr_0.2O_3−δ supports, were developed to increase H₂ yields relative to thermodynamic limitations. Pure H₂ permeate, total H₂ production, and reactor side CO conversion and H₂/CO effluent ratio were measured as a function of temperature, flow rate, CO concentration and H₂O/CO feed ratios. CO conversion, total H₂ production and yield, and the H₂/CO in the reactor side effluent increased with increasing temperature and H₂O/CO feed ratios. CO conversions of 84% and 90% were achieved at 900 °C with H₂O/CO feed ratios of 1/1 and 2/1, respectively. These respective 77% and 44% increases in CO conversion compared to feed gas condition thermodynamics resulted in 73% and 42% increases in H₂ production. Permeated H₂ and total H₂ production increased with increasing flow rate and CO concentration. Finally, membrane stability under WGS conditions was significantly improved by Zr substitution.     

Effect of Sm0.2Ce0.8O1.9 on the carbon coking in Ni-based anodes for solid oxide fuel cells running on methane fuel

To directly use hydrocarbon fuel without a reforming process, a new microstructure for Ni/Sm_0.2Ce_0.8O_2−δ (Ni/SDC) anodes, in which the Ni surface of the anode is covered with a porous Sm_0.2Ce_0.8O_2−δ thin film, was investigated as an alternative to conventional Ni/YSZ anodes. The porous SDC thin layer was coated on the pores of the anode using the sol–gel coating method. The cell performance was improved by 20%–25% with the Ni/SDC anode relative to the cell performance with the Ni/YSZ anode due to the high ionic conductivity of the Ni/SDC anode and the increase of electrochemical reaction sites. For the SDC-coated Ni/SDC anode operating with methane fuel, no significant degradation of the cell performance was observed after 180 h due to the surface modification with the SDC film on the Ni surface, which opposes the severe degradation of the cell performance that was observed for the Ni/YSZ anode, which results from carbon deposition by methane cracking. Carbon was hardly detected in the SDC-coated Ni/SDC anode due to the catalytic oxidation of the deposited carbon on the SDC film as well as the electrochemical oxidation of methane in the triple-phase-boundary.     

Status of biogas technologies and policies in South Korea

To date, there are about 49 biogas plants in South Korea that are generally recognized as economically and technically unsuccessful due to lack of knowhow, deficient technologies and policies. There is a need to analyze the status of biogas technology and policy in South Korea from the point of view of an external biogas expert, since biogas technology in South Korea has not yet been analyzed by foreign biogas experts so far. For analyzing site investigation, literature research and interviews are performed. It was found that there are several lacks of conceptual design of biogas technology, such as plant dimension, energy balance, operation knowhow. Technical and financial support for the development of biogas technology was insufficient so far. There are some policies to support biogas technologies, however financial support from different ministries seemed not to have been used efficiently. Some policies are planned excessively so that they cannot be realized on time. Based on the general policy called “Green Growth”, the Korean government plans to establish a biogas market in South Korea in order to recover energy from organic waste. For this purpose, R&D efforts should be intensified for consulting and education in national and international networks for the transfer of knowhow and technologies. Definition of the existing restrictions on the development of biogas technology is required. By developing a biogas roadmap, the creation of a biogas market could be promoted efficiently in South Korea.     

Engineered domain configuration and piezoelectric energy harvesting in 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals

The performance of cantilever piezoelectric energy harvesters using three types of piezoelectric materials, relaxor ferroelectric 0.7Pb(Mg_1/3Nb_2/3)O₃-0.3PbTiO₃ (PMN-PT) single crystals oriented along the ??110?? and ??001?? directions, and a PZT-based ceramic, were investigated. The ??110?? and ??001?? oriented PMN-PT single crystals, which have a rhombohedral phase and spontaneous polarization along the ??111?? direction, presented electromechanical coupling factor k ₃₁??s of 0.78 and 0.42, respectively. The cantilever-type energy harvester operated by 31 resonance mode generated a larger output power of 1.07 mW for the ??110?? oriented PMN-PT single crystal compared to those of the other materials. The effective electromechanical coupling factor of the piezoelectric energy harvester with the ??110?? oriented crystal also reached 0.25, not achievable with the other piezoelectric materials. These results demonstrate that the domain engineering of the piezoelectric single crystals can provide higher design flexibility for a tiny energy harvester.     

Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis

Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.     

Bimetallic multifunctional core@shell plasmonic nanoparticles for localized surface plasmon resonance based sensing and electrocatalysis

Smart bimetallic core@shell nanoparticles were fabricated based on gold nanoparticles (AuNPs) decorated with pH-sensitive polymer shell. Concretely, AuNPs having poly(4-vinylpyridine) (P4VP) on the surface were first fabricated through surface-initiated atom transfer radical polymerization (SI-ATRP). Then, they were mixed with selected metal precursor solutions followed by reduction using reducing agent. The metal NPs thus introduced were uniformly distributed in P4VP polymer shells. In order to explore the diversity and viable function of the resultant nanostructures, we controlled the size of AuNP, pH, selectivity of metal precursors, etc. We investigated the structural alteration during the sequential synthetic process. The bimetallic nanostructures of AuNP@P4VP nanocomposites containing another type of metal NP at the P4VP periphery exhibit a controlled sensing property in terms of the change in the refractive index of surrounding media and a typical electrocatalytic activity for methanol oxidation reaction.     

Enhanced heat transfer performance of alumina sponge-like nano-porous structures through surface wettability control in nucleate pool boiling

For several decades, a porous surface has been recognized as an efficient medium to increase boiling performance in a nucleate boiling regime. Most feasible porous surfaces have been studied in millimeter and micron-sized domains. It has been believed that a higher wall superheat is required to commence incipient nucleate boiling under a submicron regime. In this study, we demonstrate that a significantly enhanced pool boiling heat transfer is observed in a submicron regime through three dimensionally interconnected hybrid pores: the Alumina sponge-like nano-porous structure (ASNPS). The structural uniqueness of the ASNPS leads to an enlarged surface area, increases the potential number of the active nucleation site density, and improves the vapor–liquid menisci through the reentrant pore. Simultaneously, by changing the surface wettability with a hydrophobic self-assembled monolayer (SAM) coating, the number of active nucleation site density is improved. Eventually, the combination of the ASNPS and hydrophobic SAM coating can achieve substantial heat transfer coefficient (HTC) enhancement in the nucleate boiling. Also, the thickness of the ASNPS is a critical issue to adequately augment the HTC in pool boiling. The thickness of the ASNPS is optimized by examining the boiling performance of the ASNPS fabricated in different amounts of anodizing times. A classical mechanistic model from literature was modified and compared with the experimentally obtained data. The modified mechanistic model – with the combination of forced-convection and thin liquid film evaporation – showed reasonable predictions.     

Dose response of commercially available optically stimulated luminescent detector, Al2O3:C for megavoltage photons and electrons

This study examined the dose response of an optically stimulated luminescence dosemeter (OSLD) to megavoltage photon and electron beams. A nanoDot? dosemeter was used to measure the dose response of the OSLD. Photons of 6-15 MV and electrons of 9-20 MeV were delivered by a Varian 21iX machine (Varian Medical System, Inc. Milpitas, CA, USA). The energy dependency was <1 %. For the 6-MV photons, the dose was linear until 200 cGy. The superficial dose measurements revealed photon irradiation to have an angular dependency. The nanoDot? dosemeter has potential use as an in vivo dosimetric tool that is independent of the energy, has dose linearity and a rapid response compared with normal in vivo dosimetric tools, such as thermoluminescence detectors. However, the OSLD must be treated very carefully due to the high angular dependency of the photon beam.     

Three-dimensional asymptotic mode I/II stress fields at the front of interfacial crack/anticrack discontinuities in trimaterial bonded plates

An eigenfuntion expansion method is employed for obtaining three-dimensional asymptotic displacement and stress fields in the vicinity of the front of a crack/anticrack discontinuity weakening/reinforcing an infinite pie-shaped trimaterial plate, of finite thickness, formed as a result of bimaterial (matrix/ARC plus reaction product/scatterer) deposit over a substrate (fiber/semiconductor). The wedge is subjected to mode I/II far field loading. Each material is isotropic and elastic, but with different material properties. The material 2 or the substrate is always taken to be a half-space, while the wedge aperture angle of the material 1 is varied to represent varying composition of the bimaterial deposit. Numerical results pertaining to the variation of the mode I/II eigenvalues (or stress singularities) with Young’s moduli ratio, as well as with the wedge aperture angle of the material 1 (reaction product/scatterer) are presented. Hitherto generally unavailable results, pertaining to the through-thickness variations of stress intensity factors or stress singularity coefficients for symmetric exponentially growing distributed load and its skew-symmetric counterpart that also satisfy the boundary conditions on the top and bottom surfaces of the trimaterial plates under investigation, bridge a longstanding gap in the stress singularity/interfacial fracture mechanics literature.     

Improvement of the fracture toughness of adhesively bonded stainless steel joints with aramid fibers at cryogenic temperatures

Adhesives should be reinforced with reinforcing fibers for the bonding of adherends at cryogenic temperatures because all the adhesives become quite brittle at cryogenic temperatures. In this work, the film-type epoxy adhesive was reinforced with randomly oriented aramid fiber mats to decrease the CTE (Coefficient of Thermal Expansion) of the adhesive and to improve the fracture toughness of adhesive joints composed of stainless steel adherends at the cryogenic temperature of −150 °C. The cleavage tests of the DCB (Double Cantilever Beam) adhesive joints were performed to evaluate the fracture toughness and crack resistance of the adhesive joints. Also, the thermal and mechanical properties of the fiber reinforced adhesive layer were measured to investigate the relationship between the fracture toughness of adhesive joints and fiber volume fraction of aramid fibers. From the experiments, it was found that the crack propagated in the adhesive with the stable mode of significantly increased fracture toughness when the film-type epoxy adhesive was reinforced with aramid fiber mats. The optimum volume fraction of aramid fibers was suggested for the film-type epoxy adhesive in the adhesive joint at the cryogenic temperature of −150 °C.