Heat transfer characteristics of the latent heat thermal energy storage capsule

The characteristic variation of the rate of heat transfer to and from a latent heat thermal energy storage capsule was investigated analytically and experimentally. Basic experiments were carried out to simulate a solar energy storage capsule, using a horizontal cylindrical capsule (300 mm length, 40 mm o.d.) filled with naphthalene as the phase change material. The variation of heat flux during the processes of heat storage and removal was measured by a heat flow meter wrapped around the capsule, as the capsule was subjected to stepwise variations of the surface temperature. Finite difference calculations based on heat conduction were also carried out to compare with the experimental results. For the heat removal process, the experimental results and the calculated heat flux agreed well with each other. They showed different characteristic trends for the heat storage process, due to the effects of natural convection.     

Mo microalloying effect on the glass-forming ability, magnetic, mechanical and corrosion properties of (Fe0.76Si0.096B0.084P0.06)100-xMox bulk glassy alloys

The effect of Mo addition on the glass-forming ability (GFA), magnetic properties, mechanical properties and corrosion resistance of (Fe_0.76Si_0.096B_0.084P_0.06)_100−xMo_x (x = 0, 2, 4 and 6 at.%) bulk glassy alloys (BGAs) with high Fe contents was investigated. The 2 at.% Mo addition makes the alloy composition approach towards a eutectic point, which could result in an increase in the GFA. The BGA rod with diameters up to 3.5 mm was produced by copper mold casting. These BGAs exhibit a rather high saturation magnetization of 0.98-1.51 T and lower coercive force of 1.7-2.1 A/m. A significant improvement in corrosion resistance was observed with microalloying Mo element in 1 N H₂SO₄ solution. Furthermore, these Fe-based BGAs show super-high strength of ∼3.3 GPa and Young's modulus of 200 GPa.     

Over 27% efficiency GaAs/InGaAs mechanically stacked solar cell

We have applied an InGaAs solar cell (band GAP = 0.75 eV) to the bottom cell of the super-high-efficiency tandem solar cell aiming an over 35% conversion efficiency. The InGaAs cell which is lattice-matched to the InP substrate showed the efficiency of 5.5% under the GaAs substrate with low carrier concentration. Combining with the GaAs cell by means of a mechanically stacking technique, we obtained an efficiency of 28.8% at air mass (AM) 1.5, 1-sun. This result suggests the possibility of the cells with the efficiency of over 35% with combining a GalnP/GaAs monolithic tandem cell and the InGaAs cell (or InGaAsP cell).     

Enhancement of soft magnetic properties of FeCoNbB nanocrystalline alloys with Cu and Ni additions

The magnetic properties of annealed Fe₄₂Co₄₂Nb₇B₈Cu_0.5Ni_0.5, Fe₄₂Co₄₂Nb₆B₈Cu₁Ni₁ and Fe_42.5Co_42.5Nb₆B₈Cu_0.5Ni_0.5 alloys produced by melt spinning have been studied. By simultaneous addition of Cu and Ni elements, the soft magnetic properties of nanocrystalline FeCoNbB alloy with high Curie temperature were greatly improved. The annealed alloys show high Curie temperature of more than 1223 K and excellent soft magnetic properties, i.e., low coercivity of about 30 A/m and high effective permeability of above 5000, and these values are superior to the typical nanocrystalline HITPERM alloys for high temperature applications.     

Low-temperature synthesis of copper conductive film by thermal decomposition of copper-amine complexes

Copper conductive film was synthesized at low temperature onto a glass substrate by thermal decomposition of complexes of copper (II) formate and n-octyl amine in nitrogen atmosphere. The film generated by calcination above 110 °C indicated electrical conductivities, resulting in the lowest resistivity of 2 × 10^− 5 Ω cm by calcination at 140 °C. The copper conductive film consisted of spherical copper nanoparticles that were a mixture of large and small particles, which resulted in low volume resistivity.     

Investigation of false triggering mechanism

This paper discusses a problem that a half‐bridge circuit can generate, namely a false trigger by high‐speed switching transition. In general, a false trigger occurs by charging a gate–source capacitance because of high‐speed voltage transition and influx of current via a reverse transfer capacitance. Therefore, it is thought that the ratio of the input capacitance and the reverse transfer capacitance is important to check whether a false trigger occurs. However, we find another reason and propose a novel assumption. A novel false triggering mechanism appears by considering the source‐side parasitic inductance. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Thermal diary: Connecting temperature history to indoor comfort

To explore the relationship between thermal history and indoor comfort, surveys and measurements were conducted in Seoul, Korea and Yokohama, Japan. Fifty-two subjects were recruited from university campuses in Seoul and Yokohama during the hot season in August 2002. To collect information regarding people's daily thermal history, background questions (a thermal diary) were completed by subjects during the 24 h prior to entering in a climate chamber. Subjects changed into uniform clothing ensembles and complete thermal diary questions just prior to entering the chamber which was pre-conditioned to 28 °C and 50% relative humidity. Subjects entered the chamber and completed a set of thermal comfort questions at 10-min intervals for 1 h. Thermal history, prior to the chamber experiment, influenced the thermal sensation in chamber. Though the physical conditions in the climate chamber were identical (28 °C, 50% rh), Yokohama subjects responded with cooler thermal sensations than Seoul subjects. These subjects experienced hotter weather conditions (than the Seoul subjects) and voted that they felt cooler than the Seoul subjects who experienced cooler temperatures prior to entering the chamber. It was also found that subjects who use air-conditioning at home responded with warmer thermal sensations than the subjects who did not use air-conditioning. These results indicate that there is a strong interaction and influence of our experience with outdoor weather and our indoor thermal comfort.     

Polymeric micelles modified by folate-PEG-lipid for targeted drug delivery to cancer cells in vitro

A novel technique was developed for the formation of ligand-targeted polymeric micelles that can be applicable to various ligands. For tumor-specific drug delivery, camptothecin (CPT)-loaded polymeric micelles were modified by folate to produce a folate-receptor-targeted drug carrier. Folate-linked PEG5000-distearoylphosphatidylethanolamine (folate-PEG5000-DSPE) was added when preparations of drug-loaded polymeric micelles, resulting in folate ligands exposed to the surface. Folate-modified CPT-loaded polymeric micelles (F-micelle) were evaluated by measuring cellular uptake using a flow cytometer, fluorescence microscopy, and confocal laser scanning microscopy, and by cytotoxicity measurement. The results revealed that F-micelle showed higher cellular uptake in KB cells overexpressing folate receptor (FR) and higher cytotoxicity compared with non-folate modified CPT-loaded polymeric micelles (plain micelles) in KB cells, but not in FR-negative HepG2 cells. This result indicated that polymeric micelles were successfully modified by the folate-linked lipid.     

Radiocarbon (14C) diurnal variations in fine particles at sites downwind from Tokyo, Japan in summer

The radiocarbon ((14)C) of total carbon (TC) in atmospheric fine particles was measured at 6 h or 12 h intervals at two sites, 50 and 100 km downwind from Tokyo, Japan (Kisai and Maebashi) in summer 2007. The percent modern carbon (pMC) showed clear diurnal variations with minimums in the daytime. The mean pMC values at Maebashi were 28 ± 7 in the daytime and 45 ± 16 at night (37 ± 15 for the overall period). Those at Kisai were 26 ± 9 in the daytime and 44 ± 8 at night (37 ± 12 for the overall period). This data indicates that fossil sources were major contributors to the daytime TC, while fossil and modern sources had comparable contributions to nighttime TC in the suburban areas. At both sites, the concentration of fossil carbon as well as O(3) and the estimated secondary organic carbon increased in the daytime. These results suggest that fossil sources around Tokyo contributed significantly to the high daytime concentration of secondary organic aerosols (SOA) at the two suburban sites. A comparison of pMC and the ratio of elemental carbon/TC from our particulate samples with those from three end-member sources corroborates the dominant role of fossil SOA in the daytime.