PRECISION CUTTING OF MOLDING DIE USING SQUARE END MILL

The precision cutting of a molding die is realized using a square end mill on a 5-axis control machine. In this study, first the tool setting errors are analyzed and the compensation method of the errors is proposed. The effectiveness of compensation in precision cutting is confirmed. Next, the form accuracy of the spiral tool pass is compared with contour one in precision cutting of a spherical surface. Finally, the molding die with spherical surface is manufactured using a square end mill made out of single-crystal diamond based on the results of the compensation of the errors and the comparison of the two tool passes, and the form accuracy and surface roughness of the molding die are measured.     

Control of mesoporous and crystalline structures in turbostratic carbon derived from Fe- or Ni-doped phenolic resin

A technique to control the mesoporous structure and crystallites present in turbostratic carbon (Ts-carbon) derived from Fe- and Ni-doped phenolic resin is described. To eliminate the effect of heat treatment temperature, all of the Fe- and Ni-doped phenolic resins are carbonized at a fixed temperature of 1000 °C. The catalyst content in the obtained Ts-carbon varies from 0.001 to 5 mmol/g. Mesopores and turbostratic crystallites are formed in the Ts-carbon samples, and these increase in size as the catalyst content and its particle size increases. The turbostratic crystallites assemble to form carbon aggregates with a cup-stacked, thin tube-like, or coil-like structure. The mesopore surface area increases proportionally with the amount of turbostratic crystallites rather than the type of carbon aggregate. It is proposed that the mesopore is surrounded by turbostratic crystallites. Altering the size of the turbostratic crystallites in Ts-carbon has revealed an effective method for controlling the size and volume of its mesopores.     

Effect of N-(p-coumaroyl)serotonin and N-feruloylserotonin, major anti-atherogenic polyphenols in safflower seed, on vasodilation, proliferation and migration of vascular smooth muscle cells

Scope: The objective of this study is to investigate a vascular effect of N‐(p‐coumaroyl)serotonin (CS) and N‐feruloylserotonin (FS), major antioxidative indolic polyphenols in safflower seeds with anti‐atherogenic properties, with emphasis on effects on vascular smooth muscle cells (VSMCs). Methods and results: Both CS and FS (each 10 to 100 μM) relaxed rat femoral arteries, which were pre‐contracted by 10^?5 M phenylephrine or 50 mM KCl, independently of their endothelium. Both CS and FS also concentration‐dependently inhibited the increase of cytosolic free Ca²⁺ concentration ([Ca²⁺]_i) that was induced by KCl or 5‐hydroxytryptamine in cultured rat VSMCs. Next, we examined the effects of CS and FS on platelet‐derived growth factor (PDGF)‐BB‐evoked proliferation and migration of the VSMCs. Both CS and FS inhibited PDGF‐BB‐evoked proliferation and migration of the VSMCs in a concentration‐dependent manner. They also inhibited PDGF‐BB‐induced phosphorylation of PDGF receptor β and ERK1/2, and Ca²⁺ release from sarcoplasmic reticulum in the VSMCs in a concentration‐dependent fashion. Conclusion: These results indicated a possible vascular effect of CS/FS to inhibit the activation of VSMCs by blocking the increase of [Ca²⁺]_i and/or blocking PDGF signaling. These may explain a part of anti‐atherogenic mechanism that underlies their ability to improve vascular distensibility and to inhibit aortic hyperplasia.     

Characterization of terraces and steps on Cl-terminated Ge(111) surfaces after HCl treatment in N2 ambient

Germanium (Ge) is a promising substrate for semiconductor devices in the near future. However, wet-chemical preparations that enable the control of the structure of the Ge surface have not yet been developed. In this study, the surface structure of Ge(111) after HCl treatment is characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning tunneling microscopy (STM). XPS spectra revealed that purging with inert gas, such as nitrogen, is necessary to obtain a Ge surface free of oxide, probably because dissolved oxygen from air rapidly oxidizes the surface. Cl-terminated Ge surfaces are microscopically rough, but are composed of terraces and steps, as revealed by magnified STM images. Step edges run not along specific directions reflecting the crystallographic nature of the (111) surface but randomly. Many atomic-scale protrusions with the height of around 0.1 nm are dispersed on terraces. They are likely to be impurities such as carbon contaminants and water on Cl-terminated terraces attracted by Cl atoms with high electronegativity.     

Preparation and characterization of transparent and conductive thin films of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWNTs), synthesized using the arc-discharge method and the direct-injection-pyrolytic synthesis (DIPS) method, were dispersed in a tetrahydrofuran solution containing propylamine and used to prepare transparent and conductive thin films on PET films using an airbrush technique. The SWNTs were analyzed using vis-near infrared absorption spectroscopy, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. The surface resistivity of the SWNT films on the substrates was measured using a four-point probe conductivity measurement. The results revealed that the purity, length, and proportion of the metallic SWNTs are important factors in decreasing the sheet resistance.     

EFFECT OF DRYING ON POWDER COATING EFFICIENCY AND AGGLOMERATION IN VIBRO-FLUIDIZED BED

Glass beads of 43 μm were coated in a vibro-fluidized bed by atomizing a fine silica powder together with polyvinyl alcohol aqueous solution. The coating efficiency and weight fraction of the agglomerated particles were measured under various experimental conditions, and their dependencies on the frequency and the direction of vibration were investigated. The coating efficiency and the degree of the agglomeration among core particles correlated well with an index R. The index R was introduced to evaluate quantitatively the drying conditions in a fluidized bed.

Application of vertical vibration on the fluidized bed lowered the coating efficiency somewhat, while it prevented agglomeration. From the experimental results it was confirmed that coating with high quality and high efficiency, where few agglomerates were produced and silica powder was utilized efficiently, was possible in a vibro-fluidized bed with adequate vibration frequency and orientation of the vibration vector.     

Easy control of surface morphology through a natural phenomenon

This paper provides an innovative controlling process of surface morphology. The contact area between a liquid and a solid is strongly affected by the critical surface tension (cft) of both materials. Using this phenomenon, a wide range of morphologies, from flat surface layers to sea-grape-like surface structures, were created. Due to the bleed-out phenomenon, low-molecular-mass additive (liquid) oozed out of a precursor polymer (solid), leading to different surface morphologies depending on the cft values of the liquid (Mcft) and solid (Pcft). When Mcft < < Pcft, a flat surface layer was obtained; however, in the case of Pcft < < Mcft, the formation of a sea-grape-like surface layer was created. Tetra-butoxy-titanium and polydimethylsiloxane were used as low-molecular-mass additive and precursor polymer, respectively. After coating on titanium metal and calcination, sea-grape-like materials composed of titanium oxide and silicon oxide were obtained. Furthermore, unique characteristics (bioactivity, photocatalytic activity, and prevention of atomic diffusion) were observed. A remarkable increase in the wettability, bioactivity, and catalytic activity of materials was achieved using our simple process to create unique surface morphologies. Our proposed process is applicable to a wide range of materials and morphologies, and can be used in catalysts, biomaterials, and environmental barrier coatings.