Glyme-based nonaqueous electrolytes for rechargeable lithium cells

Poly(ethylene glycol)dimethyl ethers [(CH₃O(CH₂CH₂O)_nCH₃, n = 1, 2, 3, and 4)] are generally known as “glymes”. This study examines the conductivity, lithium ion solvation state and charge-discharge cycling efficiency of lithium metal anodes in glyme-based electrolytes for rechargeable lithium cells. 1 M (M: mol l⁻¹) LiPF₆ was used as the solute. The properties of the glymes were investigated by using a ternary mixed solvent consisting of n-glyme, ethylene carbonate (EC) and methylethylcarbonate (MEC). This was because the solubility of LiPF₆ is far less than 1 M in an n-glyme single solvent. The glyme solutions exhibited higher conductivity and higher lithium cycling efficiency than EC/MEC. The conductivity tended to increase with decreases in ethylene oxide chain number (n) and solution viscosity. The decrease in the solution viscosity resulted from the change in the lithium ion solvation structure that occurred when a glyme was added to EC/MEC. The selective solvation of the glyme with respect to lithium ions was clearly demonstrated by -NMR measurements. The lithium cycling efficiency value depended on the charge-discharge current (I_ps). When n increased there was an increase in lithium cycling efficiency at a low I_ps and a decrease in the reduction potential of the glymes. When the conductivities including those at low temperature (below 0 °C), and charge-discharge cycling at a high current are taken into account, di- or tri-glyme is superior to the other glymes tested here.     

Alternating copolymer of bithiophene and dialkylbithiazole and its tendency to align on the surfaces

New five-membered ring π-conjugated polymers composed of 2,2′-bithiophene and 4,4′-dialkyl-2,2′-bithiazole units were prepared. The polymers were soluble in 1,2-dichlorobenzene and showed a UV-vis peak at about 490 nm above 120 °C. Cooling the solution led to the appearance of new UV-vis peaks at 550 and 600 nm, which were considered to originate from self-assembled polymer molecules. Powder XRD (X-ray diffraction) data supported a well-stacked solid structure of the polymers and a highly ordered structure of a polymer film formed on a quartz glass substrate. These data revealed a strong tendency of the new polymers to self-assemble and to form an aligned structure on the surface of the substrates.     

Fracture limits of sheet metals under stretch bending

Fracture limits in sheet stretch bending were theoretically obtained on the assumption that the fracture occurs when the stretching force reaches its maximum value. From the calculated results, a fracture criterion has been presented where limit wall stretch, L_max/L₀ (L_max: limit wall length of a sheet, L₀: initial wall length), is explicitly given as a function of the non-dimensional bending curvature, t₀/R (t₀: sheet thickness, R: bending radius) and the material's work hardening exponent (n-value). To verify this criterion, three-point stretch bending tests with various punch-radii were performed on three types of aluminum sheets (A5182-O, JIS6061-T4 and JIS6N01-T5). The predicted limit wall stretch, as well as limit forming height, were in good agreement with the experimental results.     

Experimental investigation for seismic performance of framed structures having longitudinally profiled plates

This paper presents an application of hot-rolled-thickness tapered steel plates, longitudinally profiled (LP) plates, for improving seismic resistance performance of portal-framed bridge pier bents. The scale of the model was 2.0 m beam length, 2.0 m column height using centerline framing dimensions and the rectangular stiffened cross section of LP plate for flange and constant thickness plate for web. One portal model which has different tapering ratios at both the end panels of the column flanges was tested, and another model with the constant cross section of 330×250×6 mm was also tested for comparison.

The main conclusion of this study is that the optimum tapering ratio of the LP plates can lead to larger spread of yield zones with less strain concentration compared to the uniform thickness plate. Seismic design guidelines are also proposed for portal frames having LP plates.     

Stimulation of osteoclast formation by 1,25-dihydroxyvitamin D requires its binding to vitamin D receptor (VDR) in osteoblastic cells: studies using VDR knockout mice

Previous studies have shown that 1,25-dihydroxyvitamin D [1,25(OH)2D] plays important roles in the formation of osteoclasts through its actions on osteoblastic cells. We have generated mice lacking vitamin D receptor (VDR) by gene targeting (VDR-/-). These mice had tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, and exhibited similar levels of parameters for bone resorption to those in wild type mice. The present studies were undertaken to clarify whether effects of 1,25(OH)2D on osteoclast formation require VDR in osteoblasts, and to examine mechanisms of the formation of osteoclasts without VDR-mediated actions using VDR-/- mice. When wild-type calvarial osteoblasts and spleen cells were co-cultured with 1,25(OH)2D, TRAP-positive osteoclasts were formed regardless of the genotypes of spleen cells. In contrast, when osteoblasts from VDR-/- mice were co-cultured, no osteoclasts could be formed even with wild-type spleen cells. Parathyroid hormone and interleukin-1alpha stimulated osteoclast formation by co-cultures from VDR-/- mice, and the generated osteoclasts showed resorbing activity. These results demonstrate that VDR-mediated actions of 1,25(OH)2D in osteoblasts are essential for osteoclast formation by 1,25(OH)2D, and that functionally intact osteoclasts can be formed without 1,25(OH)2D actions under stimulations by other agents. It is suggested that osteoclastic bone resorption can be maintained without 1,25(OH)2D actions by other stimulatory agents.     

Electrical and Thermal Conductivities of Nickel-Zirconia Cermets

The microstructure, electrical resistivity, and thermal diffusivity of nickel-zirconia cermets have been studied. Scanning electron microscopy of the fracture surfaces of samples shows that there are some small isolated nickel granules adhering to the surface of the zirconia particles. Considering such a microstructural feature of samples and the law of mixtures, an improved model for electrical and thermal conductivity is established. With this model, the experimental results-that electrical conductivity and thermal diffusivity increase with increasing nickel content-are interpreted. Moreover, the thermal diffusivity is observed to be almost linearly related to temperature.     

Quantitative analysis of deuterium in zircaloy using double-pulse laser-induced breakdown spectrometry (LIBS) and helium gas plasma without a sample chamber

A crucial safety measure to be strictly observed in the operation of heavy-water nuclear power plants is the mandatory regular inspection of the concentration of deuterium penetrated into the zircaloy fuel vessels. The existing standard method requires a tedious, destructive, and costly sample preparation process involving the removal of the remaining fuel in the vessel and melting away part of the zircaloy pipe. An alternative method of orthogonal dual-pulse laser-induced breakdown spectrometry (LIBS) is proposed by employing flowing atmospheric helium gas without the use of a sample chamber. The special setup of ps and ns laser systems, operated for the separate ablation of the sample target and the generation of helium gas plasma, respectively, with properly controlled relative timing, has succeeded in producing the desired sharp D I 656.10 nm emission line with effective suppression of the interfering H I 656.28 nm emission by operating the ps ablation laser at very low output energy of 26 mJ and 1 μs ahead of the helium plasma generation. Under this optimal experimental condition, a linear calibration line is attained with practically zero intercept and a 20 μg/g detection limit for D analysis of zircaloy sample while creating a crater only 10 μm in diameter. Therefore, this method promises its potential application for the practical, in situ, and virtually nondestructive quantitative microarea analysis of D, thereby supporting the more-efficient operation and maintenance of heavy-water nuclear power plants. Furthermore, it will also meet the anticipated needs of future nuclear fusion power plants, as well as other important fields of application in the foreseeable future.     

Study of Substrate Preheating on Flattening Behavior of Thermal-Sprayed Copper Particles

In this study, the effect of substrate preheating on flattening behavior of thermal-sprayed particles was systematically investigated. A part of mirror-polished AISI304 substrates were preheated to 573 and 773 K for 10 min, and then exposed to an air atmosphere for different durations of up to 48 h, respectively. Contact angle of water droplet was measured on the substrate under designated conditions. It was found that the contact angle increased gradually with the increase of substrate duration after preheating. Moreover, smaller contact angle was maintained on the substrate with higher preheating temperature. Commercially available Cu powders were thermally sprayed onto the substrates with the same thermal treatment history as contact angle measurement using atmospheric plasma-spray technique. The splat shape had a transitional changing tendency from a splash splat to a disk one on the substrate with a short duration after preheating, while reappearance of splash splat with the increase of duration was confirmed. In general, wetting of substrate surface by molten particles may dominate the flattening behavior of thermal-sprayed particles. The occurrence of desorption of adsorbed gas/condensation caused by substrate preheating likely provides good wetting. On the other hand, the poor wetting may be attributed to the re-adsorption of gas/condensation on the substrate surface with the increase of duration. In addition, the shear adhesion strength of coating fabricated on blasted AISI304 substrate was enhanced on the once-heated substrate, but weakened with the increase of duration. The changing tendency of the coating adhesion strength and the wetting of substrate by droplet corresponded quite well with each other.     

Microstructures and Thermal Properties of Cold-Sprayed Cu-Cr Composite Coatings

Copper-based composites for thermal conductive components were prepared via the cold spray process, and the deposition efficiency and adhesion morphology of feedstock powders on Cu substrate were evaluated. Cu-based composites were fabricated using Cu-Cr mixed powders with their mixture ratio of 20, 35, 50, and 65 mass% Cr onto oxygen-free copper substrate with N₂ carrier gas. Cu-Cr composite coatings were investigated for their Cr content ratio, microstructures, and thermal conductivity. The Cr content ratio in the coating was approximately 50-60% of feedstock mixture ratio due to the low formability of the hard particles. Transmission electron microscopy characterizations revealed that an oxygen-rich layer exists at the Cr particle/Cu substrate interface, which contributes to the deposition of the Cr particles. After the heat treatment at 1093 K, the coatings showed denser cross-sectional structures than those before the heat treatment, and the thermal conductivity was improved as a result of the recrystallization of Cu matrix.