Search

In hard disk drives (HDDs), lubricants on disks are very important material to reduce head and disk wear. Thus, it is necessary to know changes in lubricant thickness to keep lubricant thickness constant on rotating disks. For this purpose, we have to know changes in lubricant thickness during HDD operations. We developed a simulation program to simulate changes in lubricant thickness during HDD operations numerically. First, we had simulated the changes in lubricant thickness of 10-nm-thick non-polar lubricant film under a flying head. The result corresponded to a reported experimental result. In recent HDDs, a lubricant thickness has become molecularly thin and lubricants with polar end groups have been used. In molecularly thin polar lubricants, diffusion depends on their thickness and their viscosity becomes very high. Next, we simulated the change in the lubricant thickness of 2-nm-thick polar lubricant film considering the effects of lubricant initial thickness. The simulated results showed that the changes were very small in 2-nm-thick lubricant film, but they were not confirmed with the experiment. In this paper, experimental results of the change in the thickness of molecularly thin non-polar and polar lubricants under a flying head were first measured. The simulations that took account of thickness-dependent diffusion and thin-film viscosity were then performed with the simulation parameters based on the experiments. The simulated results of lubricant distribution were in good agreement with the experimental results.

For the previous ten years, we have been studying intracellular transport of melanosoma1 proteins and their biological and biochemical functions in melanoma cells. Melanosoma1 proteins,tyrosinase, tyrosinase-related protein 1 (TYRP1) and TYRP2/DOPAchrome tautomerase (DCT), gp100/Pme117 are transported from the trans-Golgi network (TGN) to earlystage melanosomes via endosoma1 compartments. We suggest that Rab7 is involved in the vesicular transport of tyrosinase and TYRP1 and in the melanogenesis through the regulation of gp100/Pme117 maturation. TYRP1 and TYRP 2/DCT were shown to play an essential role in suppressing TYR-mediated cytotoxicity in melanocytic cells, possibly through interaction with TYR in melanosomes. We also studied apoptotic cell death of melanoma cells and death mediators. Among p53 family members, p51A (p63) induced apoptosis in both wild-type and mutant p53-expressing melanoma cells more significantly than p53 and 73β. Interferon(IFN) exerts anti-tumor activities possibly by regulating IFN-stimulated genes. Caspase-2 activation was commonly associated with induction of apoptosis in IFN一β一sensitive melanoma cells. The diacylglycero1 kinase (DGK) , expressed in several human melanoma cell lines but not in melanocytes, was a novel positive regulator of NF-KB, which suppresses TNF一α一induced melanoma cell apoptosis.

Lubricants on thin-film disks have large effects on head–disk interface characteristics. They reduce head and disk wear while thick lubricant film increases friction force between them and lubricant transfer onto head surfaces. Therefore, we have to know the lubricant behavior in many cases. Lubricant depletion due to disk rotation has been studied very well. However, the effects of flying heads have not been understood systematically until now. We developed a simulation program to numerically calculate the change in lubricant thickness under a flying head on a thin-film magnetic disk. The program included the effects of centrifugal force, shear stress from the air due to disk rotation with a flying head, and the effect of lubricant diffusion. We first calculated a change in lubricant thickness under a flying head using previously published data without the effect of diffusion. Calculated results showed fairly good agreement with the published experimental data with very high peaks on both sides of the flying head rails. With the introduction of diffusion effects, these peaks became moderate and the calculated result agreed very well with the experimental data. The coefficient of diffusion obtained to best fit to the experimental data was close to that reported in a literature. We analyzed the effects of air shear stress patterns under flying head on the change in lubricant distribution. We found that the side shapes had large effect on the distribution. We also confirmed that our program could calculate lubricant depletion on rotating disks without a flying head.

In Hard Disk Drives, lubricants are very important materials to reduce head and disk wear. Therefore, it is necessary to know the lubricant depletion under flying heads. Lubricant depletion due to flying heads has been studied experimentally. We developed simulation program to calculate numerically the change in lubricant thickness under a flying head on a thin-film magnetic disk from 10nm thick lubricant film. In recent HDDs, the lubricants thickness has become molecularly thin and polar lubricants have been used. In this paper, we took account of thickness-dependent lubricants diffusion and viscosity in our simulations to calculate a 1.2 nm thick polar lubricant film used in recent HDDs. The simulated results considering the thickness-dependent diffusion and viscosity showed that depletion was small in molecularly thin lubricant films. We considered it necessary to include thickness-dependent diffusion and viscosity in lubricant depletion simulation.Copyright © 2007 by ASME

The effect of vapor-grown carbon fiber (VGCF) content on the mechanical properties and abrasion resistance of a VGCF/polytetrafluoroethylene (PTFE) composite was investigated. A resin powder of PTFE of 50 μm in diameter was used as the matrix. The resin and VGCF were mixed by a blender mill with the VGCF content in the range 0–3 wt%. Tensile testing was performed on an Instron type tensile testing machine at a crosshead speed of 10 mm/min (strain rate: 6 × 10 −3 /s), using smooth and V-notched tensile specimens. Thermal conductivity ( λ ) was measured using the laser flash method. The coefficient of dynamic friction ( μ ′) was measured using the ball-on-disc method. The results show that the tensile strength of VGCF/PTFE composites was lower than that of the PTFE matrix and decreased as the VGCF content increased due to the weak bonding between the VGCF and PTFE matrix. The abrasion resistance of PTFE was enhanced by the addition of VGCF-H. [TANSO 2013 (No. 259) 255–60.]

Effects of annealing in a plasma gas (H, Ar, N or O) on the photo-conductivity σ p , electrical conductivity σ d , spin density and optical gap are investigated for a-Si films deposited by r.f. sputtering. The effects of annealing in H can be seen as a decrease at about 500 °C for σ d and as an increase between 200 and 400 °C for σ p , respectively. As a possible model explaining the dependences of σ p on the measurement temperature and light intensity for samples annealed in H, the conduction at localized states associated with hydrogen is proposed.