Effect of specimen thickness on the crack propagation and crack branching in delayed failure

The crack propagation and crack branching behaviors in delayed failure have been investigated on the specimens with various thickness ($\text{B = 1.5–10}\text{mm}$).The crack propagation velocity reveals a maximum value at a medium specimen thickness ($\text{B = 5}\text{mm}$). This fact can be understood by assuming the compound effect of two factors that the triaxiality of stress at crack tip as a driving force for hydrogen diffusion increases with increase of specimen thickness $\text{B}$, and that the invasion of hydrogen atoms from specimen surface increases with decrease of $\text{B}$.The stress intensity factor at crack branching, $\text{K}{}_{\mathrm{IB}}$, increases with decrease of specimen thickness $\text{B}$, and when B is 1.5 mm, the specimen fractures without showing the crack branching. The latter fact can be explained by connecting the necessary and sufficient conditions for crack branching with the decrease in height of plastic region at the crack tip in thin specimens.     

Regulation of nerve growth mediated by inositol 1,4,5-trisphosphate receptors in growth cones

The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) acts as a Ca2+ release channel on internal Ca2+ stores. Type 1 IP3R (IP3R1) is enriched in growth cones of neurons in chick dorsal root ganglia. Depletion of internal Ca2+ stores and inhibition of IP3 signaling with drugs inhibited neurite extension. Microinjection of heparin, a competitive IP3R blocker, induced neurite retraction. Acute localized loss of function of IP3R1 in the growth cone induced by chromophore-assisted laser inactivation resulted in growth arrest and neurite retraction. IP3-induced Ca2+ release in growth cones appears to have a crucial role in control of nerve growth.     

Correlations of the Specific Rates of Solvolysis of Aromatic Carbamoyl Chlorides,Chloroformates, Chlorothionoformates,and Chlorodithioformates Revisited

Additional specific rates of solvolysis are determined for phenyl chloroformate. These values are combined with literature values to give a total of 49 data points, which are used within simple and extended Grunwald-Winstein treatments. Literature values are also brought together to allow treatments in more solvents than previously for three N-aryl-N-methylcarbamoyl chlorides, phenyl chlorothionoformate, phenyl chlorodithioformate, and N,N-diphenylcarbamoyl chloride. For the last two listed, moderately strong evidence for a meaningful inclusion of a term governed by the aromatic ring parameter (I) was indicated. No evidence was found requiring inclusion of this parameter for ionization reactions with only one aromatic ring on the nitrogen of carbamoyl chlorides or for the solvolyses of the chloroformate or chlorothionoformate proceeding by an addition-elimination (association-dissociation) mechanism.     

Origin of ghost cell in Coats' disease

A morphological study of Coats' disease was performed with light and electron microscopy. The choroid was intact throughout. The pigment epithelial cells showed proliferative changes, being thickened in two or three rows. The transitional form of ghost cell was observed in contact with the pigment epithelial layer, then migrated toward the subretinal space, and finally invaded the detached retina. It was concluded that the origin of ghost cell in Coats' disease was the pigment epithelium.     

Electrochemical properties and Li deposition morphologies of surface modified graphite after grinding

Electrochemical properties and Li deposition morphologies of several kinds of carbon with different surfaces were studied. The surface conditions and Li deposition morphologies were analyzed using Raman spectroscopy and scanning electron microscopy. It appeared that the disordered carbon surface suppressed the Li dendrite deposition. Grinding methods with different clearances were adopted to modify the graphite into a desirable surface. The R-value increased from 0.10 to 0.63 after grinding to 40 μm, though a significant change in d_0 0 2 did not occur. These results suggest that disordered carbon was created on the surface without a significant change in bulk crystallinity. Thus, the reversible capacity, which is about 350 mAh g⁻¹, was the same before and after grinding. However, the Li deposition morphologies significantly changed before and after grinding. The pristine graphite had a dendritic morphology, but the ground graphite had a granular morphology. It is believed that the defects on the disordered carbon act as electrodeposition nuclei and prevent the formation of Li dendrites.     

Epitaxial growth of MgAl2O4 spinel crystals by solid-state reaction of MgO crystal with molten Al metal

Single crystals of MgAl₂O₄ spinel have been prepared epitaxially by a solid-state reaction of MgO crystal with molten Al metal under vacuum of 10^?5≈10^?6 torr at 1000≈1100°C. The growth rate was estimated to be about 0.1≈0.2 mm/hour in this temperature range. The as-grown crystals were black and opaque with low crystallinity, which was improved by heating above 1350°C. Chemical analysis showed that the crystals were slightly contaminated with Mg metal which was easily oxidized above 900°C in air.     

Growth and Characterization of Tl2Ba2CuOx(Tl-2201) Single Crystals

A new closed-atmosphere method using a gold crucible has been developed to grow single crystals of the Tl-based cuprate superconductors by a self-flux growth method. This new method can provide us mm-sized single crystals of Tl₂Ba₂CuO_x. It should be noted that the value in the resistivity ratio R(300K)/R(T_c) (RRR) of one of the as-grown crystals is 18.3. This high RRR value indicates that the newly developed method is useful to obtain extremely high-quality single crystals of Tl₂Ba₂CuO_x.     

Electrolytic deposition of lithium from non-aqueous solutions

This paper describes a study of the deposition of lithium from lithium salts (LiNO₃, LiCl, and LiClO₄) in organic solvents (CH₃CN, (CH₃)₂SO, HCONH₂, HCON(CH₃)₂, CH₃CON(CH₃)₂, and THF) using the potential-sweep technique. The current efficiency for lithium deposition was found to depend on both the solvent used and the particular anion in the electrolyte. In CH₃CON(CH₃)₂, (CH₃)₂SO, and HCON(CH₃)₂ solutions, the current efficiency for lithium deposition increased in the order: lithium chloride < lithium perchlorate < lithium nitrate whereas in CH₃CN it increased on addition of chloride. Addition of water to the LiNO₃-DMF solution also increased the current efficiency for lithium deposition. The solution which gave the highest efficiency was LiNO₃ in CH₃CON(CH₃)₂, in which efficiencies higher than 70% were obtained. The lithium metal deposited electrolytically from the LiNO₃-HCON(CH₃)₂ solution consisted of fine grains and had a high degree of crystallinity with very smooth deposit surfaces.     

Influence of particle size on the exit effect of a full-scale rolling circulating fluidized bed

This paper investigated the influence of particle size on the exit effect of a full-scale rolling circulating fluidized bed (CFB) by using the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) method. The gas–solid two-phase flow of the full-scale rolling CFB was compared with that of a simplified rolling CFB. Thus, the exit effect of the full-scale rolling CFB was clarified. In the air phase, a peak of air axial velocity v_ya was observed when the full-scale rolling CFB reached the maximum angular displacement. The particle phase possessed back mixing and radial exchange phenomena at the top and bottom of the full-scale rolling CFB, respectively. However, those phenomena were not obvious at the top and bottom of the simplified rolling CFB. The mechanism of the above-mentioned exit effect was then clarified by analyzing the forces acting on the particles under different particle sizes. Finally, the increases in particle size lead to the intensification of the peak of v_ya, particle back mixing, and radial exchange phenomena. Therefore, the intensity of the exit effect of the gas–solid two-phase flow increased as the particle size increased_. The results suggested that the small particles had the potential to promote the purification rate of the full-scale rolling CFB on account of its small exit effect.