Aerosol-to-liquid collection: A method for making aqueous suspension of hydrophobic nanomaterial without adding dispersant

This article introduces an aerosol-based technique to make aqueous suspension of hydrophobic nanomaterial without adding dispersant. The method is intended for making a test-sample for evaluating the toxicities of nanomaterial by intra-tracheal administration. The method can wet the surface of hydrophobic nanomaterial within a few seconds. After the wetting process five to ten minutes of sonication assisted with manual stirring can fully disperse the hydrophobic nanomaterials in water. Two types of TiO₂ nanomaterial were used in this study; Tayca JMT-150IB whose surfaces are coated with negatively charged hydrophobic functional group, and P25 whose surfaces are naturally hydrophilic. Nanomaterials are aerosolized by a dry-method and become micrometer-sized agglomerates. Then supersaturated water vapor is condensed onto these airborne agglomerates by using a growth tube collector. The collected suspension (CS) of hydrophobic nanomaterial (JMT-150IB) is prepared in two steps; airborne agglomerates are collected onto a flat surface then transferred to liquid-water and subsequently sonicated for complete dispersion. This method works equally well for making the CS of hydrophilic nanomaterial. Size distribution measurements of the CS show that airborne agglomerates of TiO₂ dissociate into smaller units of agglomerates once they are captured into water, and the sizes of the agglomerates are in the nanometer to sub-micrometer range. Light scattering technique is used to show that a short sonication process can reproduce the particle number concentration of the CS after long storage.

Copyright © 2017 American Association for Aerosol Research     

Littrow-type external-cavity blue laser for holographic data storage

An external-cavity laser with a wavelength of 405 nm and an output of 80 mW has been developed for holographic data storage. The laser has three states: the first is a perfect single mode, whose coherent length is 14 m; the second is a three-mode state with a coherent length of 3 mm; and the third is a six-mode state with a coherent length of 0.3 mm. The first and second states are available for angular-multiplexing recording; all states are available for coaxial multiplexing recording. Due to its short wavelength, the recording density is higher than that of a 532 nm laser.     

Tunable blue laser compensates for thermal expansion of the medium in holographic data storage

A tunable laser optical source equipped with wavelength and mode-hop monitors was developed to compensate for thermal expansion of the medium in holographic data storage. The laser's tunable range is 402-409 nm, and supplying 90 mA of laser diode current provides an output power greater than 40 mW. The aberration of output light is less than 0.05 lambdarms. The temperature range within which the laser can compensate for thermal expansion of the medium is estimated based on the tunable range, which is +/-13.5 degrees C for glass substrates and +/-17.5 degrees C for amorphous polyolefin substrates.     

Reductive decomposition of nitrate ion to nitrogen in water on a unique hollandite photocatalyst

Photocatalysis of a hollandite compound K_xGa_xSn_8−xO₁₆ (x = ca. 1.8) was examined for the reduction of nitrate ion with a reducing agent of methanol in water under UV irradiation. Hollandites have a characteristic one-dimensional tunnel structure. The hollandite powder, which was prepared by the sol–gel method and unloaded with any additives like metals, was used as the photocatalyst and its photocatalytic reaction was analyzed quantitatively by using ion chromatography and on-line mass spectrometry, and its reaction mechanism was analyzed by in-situ FT-IR. The hollandite photocatalyst showed a significant activity for the formation of N₂ from NO₃⁻. The nitrate was reduced to N₂ and NO₂⁻, while the reducing agent methanol was partly oxidized to change to formic acid. The conversion of NO₃⁻was proportional to the yields of N₂, NO₂⁻, and HCOO⁻. The present photocatalyzed decomposition of NO₃⁻ to N₂ would be a useful photocatalysis for the environmental protection of water.     

Preference for Japanese complexion color under illumination

To find the chromaticity coordinates of the “Preferred Complexion of Japanese Woman” under illumination, subjective estimation experiments were conducted on the complexions of 3 female models under each of 40 colors of illumination. The chromaticity coordinates of “Preferred Complexion” for each model were about the same together. The average chromaticity coordinates of 3 female models were (u′, v′) = (0.2425, 0.4895) under the standard illuminant D65. The “Preferred Complexion of Japanese Woman” in this experiment was compared with the “Preferred Complexion of Caucasian Woman” studied by Sanders. The “Preferred Complexion of Japanese Woman” was shifted to a slightly higher saturation and reddish in hue, compared with the actual complexion of “Japanese Woman.” On the other hand, the “Preferred Complexion of Caucasian Woman” was orange in hue, the same as the actual complexion of “Caucasian Woman.” The color shift of saturation of the “Caucasian Woman” was 3.5 times as large as that of the “Japanese Woman.” © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 269–274, 1997     

Heat transfer in fixed beds packed with cross-linked plastic particles subjected to melt-freeze cycles

To offer essential basic information for analyzing a thermal-energy storage system based on the form-stable phase change of plastics, particle-to-fluid heat transfer coefficients in fixed beds packed with cross-linked cylindrical plastic particles subjected to melt-freeze cycles were evaluated experimentally using the extended Schumann theory. A formula for estimating the heat transfer coefficient is presented. The resulting heat transfer coefficients were found to be definitely lower than those predicted from previously published work, due to the melt adhesion between adjacent plastic particles, which increases their contacting surface area and, consequently, increases the dead space in the interstitial flow region. © 1998 Scripta Technica. Heat Trans Jpn Res, 26(4): 262–274, 1997     

Heat transfer enhancement of turbulent duct flow by vortex generators attached to a large eddy break-up manipulator

An experimental study was conducted to investigate the characteristics of wall heat transfer and momentum loss for turbulent duct flow disturbed by insertion of a complicated body composed of a Large Eddy Break-Up (LEBU) plate and winglet-type vortex generators. It was found that the LEBU plate reduces the wall heat transfer in the region downstream of the insertion position and that this suppression of heat transfer could be recovered by attaching vortex generators to the LEBU plate, i.e., conspicuous heat transfer enhancement was achieved over a large streamwise distance. The spatial distribution of the heat transfer coefficient obtained shows the same features as that observed in a previous study of a flat plate turbulent boundary layer. Therefore, the flow and thermal field structure of the turbulent duct flow downstream of the inserted body should be basically the same as those in the same region of the turbulent boundary layer. The effect of a notch, open in the LEBU plate behind the vortex generator, on heat transfer and pressure drop was also examined. The notch simulates the hole of the LEBU plate to be produced in a practical application when a vortex generator is produced by punching from the original plain LEBU plate. It was found that a vortex generator with an open notch works best in augmenting the wall heat transfer and also in suppressing the increase of momentum loss. © 1999 Scripta Technica, Heat Trans Asian Res, 28(3): 189–200, 1999     

Economic analysis on small-scale forest biomass gasification considering geographical resources distribution and technical characteristics

Biomass is getting the great interest in Japan, and the cabinet approved “Biomass Nippon Strategy” in 2002 to promote the utilization of biomass. Although various projects utilizing wood biomass for energy uses have started already, many of them utilize mainly waste wood. Forest biomass remains unutilized because of the high logistic cost and the small scale of resource generation at a site. Small-scale gasification is considered as a suitable technology for forest biomass, and more than 10 demonstration plants have started to be operated recently. This study analyzes the economic feasibility of the small-scale forest biomass CHP system with gasification technology in Japan.The authors have developed the BiRReT tool, which takes input data such as geographical resource distribution and scale merit information of the target technology, and analyzes the economics of bioenergy system in target region by finding the optimal conditions; namely plant size, plant location, the number of plants, and lower generation costs. A case study in Miyagi prefecture revealed the conclusion that the system with logging residue fuel has the economic feasibility if the capital cost and the resource price will decrease from the BAU case by technological learning in the future. On the other hand, thinned wood will not be utilized as a fuel for power plants due to high fuel production cost. It is also found by the tool analysis that the technology’s scale merit has stronger impact on power generation cost in the trade-off between scale merit and the transportation cost.     

Two‐scale diffusion–deformation coupling model for material deterioration involving micro‐crack propagation

In this paper, we introduce a two‐scale diffusion–deformation coupled model that represents the aging material deterioration of two‐phase materials involving micro‐crack propagations. The mathematical homogenization method is applied to relate the micro‐ and macroscopic field variables, and a weak coupling solution method is employed to solve the two‐way coupling phenomena between the diffusion of scalar fields and the deformation of quasi‐brittle solids. The macroscopic mechanical behavior represented by the derived two‐scale two‐way coupled model reveals material nonlinearity due to micro‐scale cracking induced by the scalar‐field‐induced deformation, which can be simulated by the finite cover method. After verifying the fundamental validity of the proposed model and the analysis method, we perform a simple numerical example to demonstrate their ability to predict aging material deterioration. Copyright © 2010 John Wiley & Sons, Ltd.     

Analytical solution to compensate for thermal expansion change in photopolymer volume holograms using a tunable laser

For holographic data storage, it is necessary to adjust the wavelength and direction of the reading beam if the reading and recording temperature do not match. An analytical solution for this adjustment is derived using first-order approximations in a two-dimensional model. The optimum wavelength is a linear function of the temperature difference between recording and reading, and is independent of the direction of the reference beam. However, the optimum direction of incidence is not only a linear function of the temperature difference, but also depends on the direction of the reference beam. The retrieved image, which is produced by a diffracted beam, shrinks or expands slightly according to the temperature difference.