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Abstract The dynamics of CH 4 replacement in the CH 4 hydrate with saturated liquid CO 2 at 273.2 K was measured with a high pressure optical cell. The results showed that CH 4 in the hydrate gradually moved to the liquid CO 2 phase while CO 2 in the liquid phase penetrated into the hydrate from the quantitative analysis. The decomposing process of the CH 4 hydrate during the replacement was analyzed with in situ Raman spectroscopy, which allowed us to distinguish the cage structure of the CH 4 hydrate and discuss the microscopic view of the replacement in the hydrate. It was found that the decomposition of the medium cage (M-cage) in the CH 4 hydrate proceeded faster than that of the small cage (S-cage). The observed rate difference could be related to the stability of the S-cage in the CH 4 hydrate or the re-formation tendency of CH 4 and water molecules in the S-cage after decomposing the hydrate structure, whereas the guest molecule exchange of CH 4 with CO 2 could occur in the M-cage. Based on the experimental data, we developed a kinetic model for calculation of the CH 4 remaining in the hydrate considering the decomposition rate difference between the M-cage and S-cage in the CH 4 hydrate. The results indicate that the driving force could be the fugacity difference between the fluid phase and the hydrate phase for the replacement process.

The technique of moving-window two-dimensional heterospectral (MW2DHetero) correlation spectroscopy is proposed. This computational method is based on the ideas of perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy and two-dimensional heterospectral correlation analysis. Not only small spectral variations, but also detailed bands assignments were captured using the analysis. This method was applied to near-infrared (NIR) spectra in the 10 000–4000 cm−1 region and mid-infrared (mid-IR) spectra in the 5000–1200 cm−1 region, which were simultaneously detected using a dual-region spectrometer. Near-infrared and mid-IR spectra collected during an alcoholic fermentation process using a solution containing glucose and fructose were reported. Slight time differences for the consumption of sugars compared with the production of ethanol were found between 50 and 150 min. It was concluded that these slight time differences are evidence for different consumption times between glucose and fructose during the fermentation process. The result proved a possibility of the selective monitoring of the simultaneous reaction processes between productive and consumptive components.

Proton conducting ceramics (PCC) cells are promising energy conversion devices that enable high efficiency energy conversion at lower temperature range, solving the challenge of conventional solid oxide cells (SOCs) due to the high operating temperature. Electrochemical performance and chemical stability of PCC electrolyte has been investigated in recent studies, suggesting that rare-earth doped Ba(Zr,Ce)O3 perovskite-type ceramics are optimal materials exhibiting high proton conductivity and chemical stability during operations. On the contrary, mechanical stability of these PCC electrolyte materials has not been evaluated despite the fact that the mechanical properties are critically important for achieving long-term stable operation as fuel cells or electrolyser cells. For the development of conventional SOCs, mechanical stability during high temperature operation was one of the most significant challenges to deal with, which was attained as a result of detailed studies on in-situ elastic properties of composing materials such as oxygen ion conducting electrolytes and residual stresses. Similarly, for PCC cells, mechanical properties of cells and composing materials have been of significant interest in order to achieve mechanically stable long-term operation, even though PCC cells operate at lower temperature than SOCs. Furthermore, the metal-supported (MS) structure which provides superior mechanical robustness compared to anode-supported (AS) structure is expected to be applied effectively to PCC cells, which are called proton conducting ceramics – metal-supported cells (PCC-MSCs), leading to greater necessity of the mechanical evaluation of the cells and composing materials. Electrolyte is the most crucial component in an electrochemical cell and must be mechanically stable because ion transport and gas tightness made by electrolyte determines electrical performance. However, there has been important concern that larger thermal stresses might be introduced in PCC cells compared to SOCs, resulting from the thermal expansion coefficient (TEC) mismatch between the electrode and electrolyte and from the chemical expansion by the hydration that occurs in a certain temperature range. The PCC electrolyte is highly in need of investigation on in-situ mechanical properties, especially on elastic properties. In this study, elastic properties of electrochemically promising PCC, Y-doped Ba(Zr,Ce)O3 perovskite-type ceramics, were investigated under high temperature conditions. Elastic moduli such as Young’s modulus and Poisson’s ratio were measured by the method that we previously developed for elastic investigation in high temperature conditions using ultrasonic waves. This method enables highly accurate and repetitive examination of elastic properties at high temperatures in materials with poor sinterability including PCC by measuring ultrasonic sound velocities in pellets typically fabricated for electrochemical tests. Pellets of BaZr1-xYxO3-δ (BZY) with different concentrations of doped yttrium, BaZr0.9Y0.1O3-δ (BZY10), BaZr0.85Y0.15O3-δ (BZY15), and BaZr0.8Y0.2O3-δ (BZY20), were fabricated. Additionally, pellets of BaZryCe1-yY0.1O3-δ (BZCY) with different ratio of Ce to Zr, BaZr0.7Ce0.2Y0.1O3-δ (BZCY721) and BaZr0.8Ce0.1Y0.1O3-δ (BZCY811) were fabricated. Powders of PCCs above were consolidated to be thick rounded shape and sintered in air. Each prepared sample was set in an electric furnace in laboratory air atmosphere and sound velocities were measured with the sample slowly heated up to 700 °C and subsequently cooled down to room temperature to calculate elastic moduli at each measuring point. In the first series of heating and cooling measurements for as-sintered samples, hysteresis on elastic moduli in intermediate temperature range was observed. We repeatedly conducted a series of heating and cooling measurements several times, and then the hysteresis was not observed any further. Fig.1 shows final state Young’s modulus of BZCY721, BZCY811, and BZY10 (BZCY901) without hysteresis. Elastic moduli at room temperature have not changed through multiple heating and cooling measurements, and crystal structures and lattice parameters were also confirmed to remain constant by x-ray diffraction (XRD) analysis. The hysteresis found in a specific temperature range suggests that elastic moduli were influenced presumably by a change in defect structure of PCC caused by hydration or defect association of oxygen vacancies and dopants. At room temperature, Young’s modulus decreased with the increment of Ce concentration by 16 % from BZY10 to BZCY721. When materials have the same crystalline structure, Young’s modulus generally decreases as mean atomic volume of the base crystal increases. Because BaCeO3 has larger mean atomic volume than BaZrO3, this observation is qualitatively reasonable. However, in high temperatures, the difference became significant only for BZCY721, Young’s modulus decreased by 30 % from that at room temperature in BZCY721. These results suggest that Ce substitution causes different high temperature dependences. Figure 1

Abstract In this work, the effects of trailing edge (TE) cutback on the turbulent flow field and the aerodynamic loss of a turbine blade are investigated by Large-Eddy-Simulation (LES). A high-fidelity LES code was first developed based on a high-order finite difference method and applied to the simulation. The effects of the TE cutback on the blade surface boundary layer, pressure distribution, and loss generation are then discussed on the basis of time-mean flow fields of LES. The results represent that the cutback changed the boundary layer thickness just upstream of the TE and the base pressure around the TE, resulting in larger aerodynamic loss. Next, the time-dependent flow dynamics in the cascade is investigated. The results indicate that the dominant pressure fluctuation after the blade was influenced by the cutback. Furthermore, the phase-locked flow field is analyzed to reveal the flow dynamics responsible for the pressure fluctuation. Finally, the LES approach could clarify the underlying mechanisms of performance degradation of a turbine blade that caused by TE cutback.

For global survival, we need to launch a rapid regeneration of the nuclear power industry. The replacement of the present fossil fuel industry requires a doubling time for alternative energy sources of 5–7 years and only nuclear energy has the capability to achieve this. The liquid metal cooled fast breeder reactors (LMFBR) have the best breeding criteria but the doubling time exceeds 20 years. Further, the use of plutonium in these systems has the potential of nuclear proliferation. The Thorium Molten-Salt Nuclear Energy Synergetic System [THORIMS-NES], described here is a symbiotic system, based on the thorium–uranium-233 cycle. The production of trans-uranium elements is essentially absent in Th–U system, which simplifies the issue of nuclear waste management. The use of 233 U contaminated with 232 U as fissile material, instead of plutonium/ 235 U makes this system nuclear proliferation resistant. The energy is produced in molten-salt reactors (FUJI) and fissile 233 U is produced by spallation in Accelerator Molten-Salt Breeders (AMSB). This system uses the multi-functional ‘‘single-phase molten-fluoride” circulation system for all operations. There are no difficulties relating to ‘‘radiation-damage”, ‘‘heat-removal” and ‘‘chemical processing” owing to the simple ‘‘idealistic ionic liquid” character of the fuel. FUJI is size-flexible, and can use all kinds of fissile material achieving a nearly fuel self-sustaining condition without continuous chemical processing of fuel salt and without core-graphite replacement for the life of the reactor. The AMSB is based on a single-fluid molten-salt target/blanket concept. Several AMSBs can be accommodated in regional centers for the production of fissile 233 U, with batch chemical processing including radio-waste management. FUJI reactor and the AMSB can also be used for the transmutation of long-lived radioactive elements in the wastes and has a high potential for producing hydrogen-fuel in molten-salt reactors. The development and launching of THORIMS-NES requires the following three programs during the next three decades:

AbstractIn neuro‐physiology, it is important to record neural impulses from the central neural system simultaneously. For this purpose, a silicon substrate which forms a multimicroelectrode was fabricated and a precise fabrication of a 10 μm thick microelectrode with a 30 μm wide tip was achieved by using Si dry etching. The high‐quality insulation of the electrode in a physiological solution was obtained by using Ta and high‐temperature CVD Si3N4. However, Ta itself is not adequate for the recording site because it is oxidized easily in an electrolyte causing the increase of the electrode impedance. Platinum‐black was electroplated on the titanium surface in order to stabilize and reduce the electrode impedance. The interelectrode crosstalk between electrodes and signal attenuation due to the parasitic capacitances were 0.4% and 4.4%, respectively.

Abstract A two-compartment photoelectrochemical cell consisting of a TiO2 photoanode, Nafion membrane and platinized tin oxide glass as the cathode was constructed. The anolyte and catholyte were 1 M NaOH and 1 M Na2S4, respectively. Illumination of the photoanode resulted in oxygen evolution in the anodic compartment simultaneously with the reduction of tetrasulfide in the cathodic compartment. The mechanism of such a photoelectrochemical oxygen evolution is discussed throughout and the possible application of this reaction in solar water splitting is mentioned.

Abstract The efficiency of microbial electron transfer is fundamental for determining the performance of fermentative hydrogen/methane production. To facilitate microbial electron transfer, conductive magnetite nanoparticles (MNPs) were added into a cascading dark fermentation and anaerobic digestion system that was inoculated with Enterobacter aerogenes ZJU1 and methanogenic activated sludge (MAS), respectively. During the hydrogen-producing stage, the ratio of NADH/NAD+ and the activities of hydrogenase and electron transport system (ETS) of E. aerogenes ZJU1 were all increased by dosing 200 mg/L MNPs, which was conducive to hydrogen production through the NADH-dependent pathway. In the presence of 200 mg/L MNPs, hydrogen production increased by 21.1%, while subsequent methane production improved by 22.9%. Electrochemical analysis demonstrated the improvement in extracellular electron transfer capacity of MAS after adding MNPs, which can be ascribed to the contribution of MNPs and electrochemically active extracellular polymeric substances (EPS) induced by MNPs, such as humic acid-like and fulvic acid-like substances. Bacteria Syntrophomonas and Archaea Methanosarcina were the dominating enriched syntrophic partners, and the expression of functional genes involved in CO2 reduction to methane pathway was found to increase. Therefore, a more efficient fermentative hydrogen and methane co-production system was established by improving microbial electron transfer with the addition of MNPs.

Abstract In general, it is well known that the energy efficiency of a grinding process decreases with decrease in produced particle size, increase in grinding time, or increase in input energy. In this paper, a grinding method, based on fracture mechanics, to produce ultrafine particles has been investigated. We define the size reduction energy as the elastic strain energy which is stored in the specimen up to the instant of fracture. Assuming that the kinetic energy of a grinding medium or a particle were converted completely into fracture energy, the relationship between impact velocity required to fracture and particle size, or between impact velocity of a grinding medium required for a particle to fracture and mass of a medium have been calculated. As a result, the assumption that, for ultrafine grinding, a grinding medium collides against a particle was found to be more feasible than that a particle collides against a medium. It was necessary to increase the collision probability because the number of particles produced varies inversely as the cube of particle size. The experimental verification of the above considerations was performed using a ball mill. Ground products smaller than 3 μm with a median diameter of about 0.3 μm were obtained.