Monte Carlo simulations of spectral albedo for artificial snowpacks composed of spherical and nonspherical particles

The optical properties of snowpacks composed of spherical and nonspherical particles artificially prepared in a cold laboratory are investigated by measuring spectral albedos. The measured spectral albedo in the spectral region lambda=0.35-2.5 microm is compared with the theoretically calculated albedo, for which a Monte Carlo radiative transfer model is employed for multiple scattering combined with the Mie theory and the ray-tracing technique for single scattering by snow particles. Since the spherical particles are a little aggregate, the effects of a cluster of the spheres on snow albedo are examined using a generalized multiparticle Mie-solution model [Appl. Opt. 34, 4573 (1995); J. Quant. Spectrosc. Radiat. Transf. 79-80, 1121 (2003)]. The snow albedo of a cluster of the spheres can be represented with that of the singe sphere slightly larger than its component of the cluster in case of small grains. The observed albedos for the spherical snow particles agree with the theoretically calculated ones for the snow grain size measured in the snow pit work. The snow albedos for the nonspherical particles, which were dendrites, are influenced by the branch width and the branch length, based on a comparison of the theoretically calculated albedo by using circular cylindrical snow particles and the observed albedo. The snow albedo in the near-infrared region depends on the branch width only when the branch length is sufficiently greater than the branch width. The comparison between the spherical and nonspherical snow particles indicates that the spectral albedo of the nonspherical particles can be represented by using an equal volume-area ratio sphere.     

Practical Design for Improving the Sensitivity to Search for Dark Matter Axions with Rydberg Atoms

A microwave single-photon detector was developed with highly-excited alkaline Rydberg-atoms in a cooled resonant cavity to search for dark matter axions. This detector belongs to a microwave single-photon counter, thus being free from the standard quantum limit (SQL). High sensitivity of the present detector system was demonstrated by measuring the thermal blackbody radiations in the cavity at temperatures as low as 70 mK where the sensitivity is below the SQL. The detection sensitivity of the present system is mainly limited by stray electric fields present in the detection region. Practical design of a new experimental scheme with a guiding electric field through the atomic-beam trajectory is here presented and discussed to avoid the effect of stray electric field and thus to improve the detection sensitivity.      

Analysis of biphasic lubrication of articular cartilage loaded by cylindrical indenter

Combination of theoretical biphasic analyses and corresponding experimental measurements for articular cartilage has successfully revealed the fundamental material properties and time-depending mechanical behaviors of articular cartilage containing plenty of water. The insight of load partitioning between solid and fluid phases advanced the prediction of the frictional behavior of articular cartilage. One of the recent concerns about biphasic finite element (FE) analysis seems to be a dynamic and physiological condition in terms of mechanical functionality as a load-bearing for articular joint system beyond material testing, which has mainly focused on time-dependent reaction force and deformation in relatively small and low speed compression. Recently, the biphasic FE model for reciprocating sliding motion was applied to confirm the frictional effect on the migrating contact area. The results indicated that the model of a cylindrical indenter sliding over the cartilage surface remarkably sustained the higher proportion of fluid load support than a condition without migrating contact area, but the effectiveness of constitutive material properties has not been sufficiently evaluated for sliding motion. In our present study, at the first stage, the compressive response of the articular cartilage was examined by high precision testing machine. Material properties for the biphasic FE model, which included inhomogeneous apparent Young's modulus of solid phase along depth, strain-dependent permeability and collagen reinforcement in tensile strain, were estimated in cylindrical indentation tests by the curve fitting between the experimental time-dependent behavior and FE model simulation. Then, the biphasic lubrication mechanism of the articular cartilage including migrating contact area was simulated to elucidate functionality as a load-bearing material. The results showed that the compaction effect on permeability of solid phase was functional particularly in the condition without the migrating contact area, whereas in sliding condition the compaction effect did not clearly show its role in terms of the proportion of fluid load support. The reinforcement of solid phase, which represented the collagen network in the tissue, improved the proportion of fluid load support especially in the sliding condition. Thus, a functional integration of constitutive mechanical properties as a load-bearing was evaluated by FE model simulation in this study.     

Development of high 1-deoxynojirimycin (DNJ) content mulberry tea and use of response surface methodology to optimize tea-making conditions for highest DNJ extraction

Mulberry 1-deoxynojirimycin (DNJ), a potent α-glucosidase inhibitor, suppresses postprandial blood glucose, thereby possibly preventing diabetes mellitus. At present, mulberry dry teas are commercially supplied as functional foods in many countries, but these products may not provide an effective dose (6 mg DNJ/60 kg human wt) due to their low DNJ content (about 100 mg/100 g of dry wt). Therefore, development of tea with higher DNJ content is desirable. To do this, we investigated distribution of DNJ content and α-glucosidase inhibitory activity in 35 Thai mulberry varieties. DNJ content in young leaves varied among mulberry varieties from 30 to 170 mg/100 g of dry leaves. Varieties having highest DNJ content were Kam, Burirum 60 and Burirum 51. Leaf position affected DNJ content: shoots > young leaves > mature leaves. DNJ concentration and α-glucosidase inhibitory activity were highly correlated (r = 0.84), suggesting that α-glucosidase inhibitory activity of mulberry leaves is mainly due to DNJ. Consequently, high DNJ content mulberry tea was produced from shoots of varieties such as Burirum 60, which contains 300 mg/100 g of dry wt. Tea-making conditions were optimized for highest DNJ extraction using response surface methodology. Approximate 95% of total DNJ in high DNJ content dry tea was extracted when temperature was maintained at 98 °C for 400 s; these conditions could be applicable for preparation of commercial products with high DNJ content. One cup (230 ml, a normal serving) of DNJ-enriched mulberry tea contained enough DNJ (6.5 mg) to effectively suppress postprandial blood glucose.     

Thermal and insulating properties of epoxy/aluminum nitride composites used for thermal interface material

We synthesized an epoxy matrix composite adhesive containing aluminum nitride (AlN) powder, which was used for thermal interface materials (TIM) in high power devices. The experimental results revealed that adding AlN fillers into epoxy resin was an effective way to boost thermal conductivity and maintain electrical insulation. We also discovered a proper coupling agent that reduced the viscosity of the epoxy‐AlN composite by AlN surface treatment and increased the solid loading to 60 vol %. For the TIM sample made with the composite adhesive, we obtained a thermal conductivity of 2.70 W/(m K), which was approximately 13 times larger than that of pure epoxy. The dielectric strength of the TIM was 10 to 11 kV/mm, which was large enough for applications in high power devices. Additionally, the thermal and insulating properties of the TIM did not degrade after thermal shock testing, indicating its reliability for use in power devices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

DETERMINATION OF HIGH MOLECULAR WEIGHT β-GLUCAN IN WORT AND BEER USING A POST-COLUMN CALCOFLUOR FLOW-INJECTION-ANALYSIS (FIA) METHOD

To eliminate the influence of maltose, ethanol, low molecular weight β-glucan and an inhibitor of the calcofluor fluorescence reaction in wort and beer on the measured values of a calcofluor-FIA, a post-column calcofluor-FIA method has been developed using a short-size gel permeation chromatography column (6.0 × 50 mm). A column packed with polyhydroxymethacrylate gel (molecular weight exclusion limit, 100,000) was found to be the most appropriate for this system. This short column allowed rapid and specific measurement of high molecular weight β-glucan in a few minutes without the influence of the fluorescence inhibitor, maltose and ethanol which have molecular weights of less than 1000 daltons. Because the low molecular weight β-glucan responsible for the scatter caused by a slight difference in measuring conditions such as temperature, calcofluor concentrations, sample volumes, etc., was separated through the use of the column, the measured values by the post-column calcofluor-FIA method hardly fluctuated under different conditions. Though it has been recognized that dilution of a sample could affect a calcofluor FIA, the new system was not influenced. This also made it possible to measure the β-glucan content in dark-coloured samples (even over 100 EBC colour units). The measured values by the post-column FIA showed a high correlation (r² = 0.993) with those obtained by the enzymatic method (the McCleary method).     

A comparative study of the emotional assessment of automotive exterior colors in Asia

This article compares color assessments of automotive exteriors at four locations in China, Thailand and Japan. This study employed painted panels of twelve colors, thirty sensory words and fifteen pairs of emotion variables. It also used reference figures of nine cars that included four styling categories, namely sedans, compacts, sport utility vehicles and sports cars. The results of like-dislike tests revealed that basic automotive exterior colors, such as black, white and red, were highly preferred across locations. However, geographical differences are apparent in the preference for some non-basic colors. To elucidate these geographical differences, a Chi-square test and principal component analysis were performed on the data on emotion variables. The results revealed both similarities and differences in color preferences among the four locations. Color preferences were similar in Hong Kong and Shanghai when simply evaluated by color samples. However, similar preferences for automotive exterior colors were observed in Hong Kong, Kyoto and Bangkok, but not in Shanghai. These results suggest that there is fluctuation in the emotion evoked by a color when the color is considered in the context of automotive exteriors. Therefore, this study indicates that automotive sales can be secured in the global marketplace by creating a single palette of exterior colors based on similar color preferences across countries. However, these results also indicate that preparing market-specific automotive-color line-ups can be an effective marketing strategy.     

Supercritical fluid‐assisted electroless metal plating onto aramid films: The influence of thermal treatment

Although the production of electro‐conductive aramid fibers is efficient, the method needs to be modified before it can be applied to aramid films. Whereas impregnation of an aramid film with a metal complex using supercritical CO₂ is achievable, the relatively low adhesion strength of the metal layer applied using electroless copper plating is problematic. To solve this problem, thermal treatment was conducted before, after, or both before and after electroless plating. The rationale for using thermal treatment to improve the adhesiveness of the plated layer was based on the findings that (1) an aramid film contains a significant amount of water (about 3.5 % w.o.f.), which might have a negative impact on adhesion; and (2) because an impregnated metal complex liberates metal catalyst by thermal decomposition during impregnation, a supplementary thermal action might liberate more catalyst and thereby improve adhesion. We found that thermal treatment improved adhesion of the metal layer to the aramid film. Moreover, we discovered that with respect to electroless copper plating, a short time‐lag was crucial to obtaining a thin and homogeneous metal layer with strong adhesion. In addition, we demonstrate the affinity of an aramid film for Pd(acac)₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011