Improved technique for measuring the size distribution of black carbon particles in liquid water

We developed an improved technique for measuring the size distribution of black carbon (BC) particles suspended in liquid water to facilitate quantitative studies of the wet deposition of BC. The measurement system, which consists of a nebulizer and a single-particle soot photometer, incorporates two improvements into the system that we developed earlier. First, we extended the upper limit of the detectable BC size from 0.9 μm to about 4.0 μm by modifying the photo-detector for measuring the laser-induced incandescence signal. Second, we introduced a pneumatic nebulizer (Marin-5) with a high extraction efficiency (～50.0%) that was independent of particle diameter up to 2.0 μm. For BC mass concentrations less than 70 μg L^?1, we experimentally showed that the diameters of BC particles did not appreciably change during the Marin-5 extraction process, consistent with theoretical calculations. Finally, we demonstrated by laboratory experiments that the size distributions of ambient BC particles changed little during their growth into cloud droplets under supersaturation of water vapor. Using our improved system, we measured the size distributions of BC particles simultaneously in air and rainwater in Tokyo during summer 2014. We observed that the size distributions of BC particles in rainwater shifted to larger sizes compared with those observed in ambient air, indicating that larger BC particles in air were removed more efficiently by precipitation.

Copyright © 2016 American Association for Aerosol Research     

Development of sheet-like dielectric barrier discharge microplasma generated in supercritical fluids and its application to the synthesis of carbon nanomaterials

A two-dimensional, sheet-like dielectric barrier discharge microplasma that can be generated in supercritical fluids was developed. With this type of plasma, generated in supercritical xenon, nanocrystalline diamonds and diamondoid-like sp³ bonded nano-hydrocarbons were synthesized by using adamantane as a precursor and seed. Pressure and temperature were set close to the critical point of xenon at 6.3 MPa and 290.2 K, respectively. The peak-to-peak voltage for microplasma generation was between 3.4 and 7.1 kV, at a frequency of 10 kHz and the power consumption of the microplasma determined from the I-V measurements reached about 30 mW. Transmission electron microscopy analysis of the lattice of the synthesized particles revealed crystal structures similar to those observed in nanodiamonds, while micro-Raman spectra yielded features also found in Raman and ab initio computational studies of diamondoids.     

Synthetic Biomarker Design by Using Analyte‐Responsive Acetaminophen

The use of synthetic biomarkers is an emerging technique to improve disease diagnosis. Here, we report a novel design strategy that uses analyte‐responsive acetaminophen (APAP) to expand the catalogue of analytes available for synthetic biomarker development. As proof‐of‐concept, we designed hydrogen peroxide (H₂O₂)‐responsive APAP (HR‐APAP) and succeeded in H₂O₂ detection with cellular and animal experiments. In fact, for blood samples following HR‐APAP injection, we demonstrated that the plasma concentration ratio [APAP+APAP conjugates]/[HR‐APAP] accurately reflects in vivo differences in H₂O₂ levels. We anticipate that our practical methodology will be broadly useful for the preparation of various synthetic biomarkers.     

The role of silanol groups on the reaction of SiO2 and anhydrous hydrogen fluoride gas

It is essential to etch SiO₂ for producing silica glass components, semiconductor devices, and so on. Although wet-etching with hydrogen fluoride (HF) solutions is usually employed for this purpose, it faces a drawback that microstructures stick during the drying of the solution. To overcome this problem, we have developed a dry-etching technique with gaseous HF at high temperatures. In the present study, an interesting phenomenon was found that silicon thermal oxides were much less etched than vitreous silica by gaseous HF. Such difference had not been found in wet- or humid HF gas etching. Because their bulk chemical formulae are the same (SiO₂), it was suggested that the surface species affected the reaction rate. In fact, preprocessing with water vapor plasma remarkably increased the etching rate on the thermal oxides layer, and vacuum heating almost completely suppressed the reaction on the vitreous silica and the plasma-treated thermal oxides. These results indicate that the surface silanol groups enhance the reaction between SiO₂ and gaseous HF. Based on the results, a model of chain reaction for SiO₂ and gaseous HF was proposed, where the surface silanol groups act as the reaction center.     

Anode/Cathode Dual-Purpose Aluminum Current Collectors for Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc (Zn)-ion batteries (RAZIBs), which use non-flammable aqueous electrolytes and low-cost electrode materials, show great potential to boost the development of safe, cost-effective, and highly efficient energy storage systems. The adoption of lightweight and inexpensive aluminum (Al) as current collectors seems to be a good vision, but Al exhibits an easily-corroded nature and a high impedance in aqueous electrolytes, making it a challenge to realize the utilization of Al current collector in RAZIBs. In this study, through the direct current magnetron sputtering, niobium (Nb) coated Al (Al-Nb) foils are prepared, which shows superior corrosion-resistance in an aqueous solution, while maintaining a satisfying electronic conductivity. Moreover, the Al-Nb foils can be adopted to both anode and cathode current collectors while exhibiting high coulombic efficiency and good cycling stability even when they are tested under a condition that can meet the real-world application demands, e.g., the Zn||Al-Nb half-cell shows an average coulombic efficiency of 99.17% in 320 cycles under a current density of 25 mA cm⁻² and a galvanizing capacity of 6.25 mAh cm⁻². The superior performance of the modified Al current collectors may mark a significant step toward the development of high-energy-density aqueous batteries.     

Automatic background music generation based on actors' mood and motions

Since adding background music and sound effects even to short animations is not simple, an automatic music generation system would help improve the total quality of computer generated animations. This paper describes a prototype system which automatically generates background music and sound effects for existing animations. The inputs to the system are music parameters (mood types and musical motifs) and motion parameters for individual scenes of an animation. Music is generated for each scene. The key for a scene is determined by considering the mood type and its degree, and the key of the previous scene. The melody for a scene is generated from the given motifs and the chord progression for the scene which is determined according to appropriate rules. The harmony accompaniment for a scene is selected based on the mood type. The rhythm accompaniment for a scene is selected based on the mood type and tempo. The sound effects for motions are determined according to the characteristics and intensity of the motions. Both the background music and sound effects are generated so that the transitions between scenes are smooth.     

Analysis of two-regional flow in liquid composite molding

This study investigates the two-regional flow in Liquid Composite Molding (LCM) with emphasis on the race tracking phenomenon. An equivalent permeability is introduced to describe the flow capacity in the fiber free region. A lumped permeability is also used to further simplify the flow modeling by averaging the flow across the flow direction. Both the equivalent permeability approach and the lumped permeability approach were verified with experiments. It is found that they are capable of modeling the race tracking effects in LCM.