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Recently, many toiletries claiming inclusion of platinum (Pt), silver (Ag) and gold (Au) as additives are sold in ordinary cosmetics shops. However, their concentrations are not clearly indicated. In the present work, these toiletries were analyzed for heavy metal elements by instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS), and the particle sizes were observed by scanning electron microscope (SEM) and the constitutions of the small particles were analyzed by energy dispersive X-ray spectroscopy (EDX). The concentrations of Pt in the toiletries observed were from 1 to 80 ppm. The lower detection limit of Pt by INAA was about 1 ppm because of the presence of sodium in high concentrations for those samples. Consequently, some toiletries which should have had Pt according to the manufactures were found not to contain Pt probably because it was less than the detection limit. On the other hand, there were a few toiletries that were found to contain Ag although the addition of Ag was not mentioned by the manufactures. It is considered that these non-indicated Ag were included as impurities of the added Au. The concentrations of the non-indicated Ag were even higher than those of the indicated Ag. A very small amount of Sr, which was nominated in the negative list of Japan, was also detected in 2 out of 5 kinds of toiletries analyzed by ICP-MS.

Carbon-14 is one of the critical radionuclides for the dose estimation from nuclear fuel reprocessing plants and nuclear waste disposal facilities. To assess the impact on public health caused by carbon-14 released from these nuclear facilities in Japan, a reasonable estimation of internal dose from the rice ingestion is necessary because rice is a staple food. Therefore, we are developing a dynamic compartment model to predict carbon-14 behavior in atmosphere – paddy soil – rice plant system and carbon-14 concentration in rice by using a migration prediction code, MOGRA. In this model, growing curves of “leaf and stem part” and “ear part” of a rice plant were fitted to sigmoid curves. The transfer coefficients between the compartments were estimated by using sub-models and parameters which describe transfer mechanisms of carbon in a rice paddy field, such as photosynthesis, translocation and respiration in a rice plant. A validation study of the model, carried out with “Rice Scenario” presented by the IAEA EMRAS (Environmental Modelling for RAdiation Safety) project, showed that the developed model can be practically used to predict the carbon-14 concentration in rice. The model was also applied for hypothetical releases of carbon-14 from nuclear fuel reprocessing plant. In addition, parameter sensitivity analyses were carried out to select critical parameters.

Among athletes, Staphylococcus aureus is thought to be transmitted by close physical contact with carriers. Nevertheless, evidence is limited with regard to both the tracking of individual strains and the role of S. aureus on the skin’s surface. We investigated its transmission using molecular genotyping and the presence of S. aureus on the skin during exercise. In the first study, nasal samples were obtained from 172 athletes over a period of up to one year. The 200 strains of S. aureus collected from these athletes were genotyped, and transmission of S. aureus was detected by phage open reading frame typing (POT). In the second study, the presence of S. aureus on the skin’s surface was compared between nasal carriers (n=9) and non-nasal carriers (n=9), who had participated in the first study. In the first study, 10 cases of transmission were confirmed. In the second study, exercise-induced sweating increased S. aureus isolates from the skin’s surface (before vs. after exercise: 5.2±5.4 vs. 41.7±40.6 CFU/ml) in nasal carriers. In 5 of 9 nasal carriers, S. aureus isolates from the skin’s surface were clonally identical to those from the nares. These results identify a major route of S. aureus transmission among athletes and provide insight into the role played by exercise-induced sweating in nasal carriers.

This paper describes a new type of power amplifier (PA) module with a predistortion function and can be applied to a N-CDMA (narrow-band CDMA system defined in IS-95B Standard) handset terminals. Distortion compensation technology to improve the efficiency of the PA is discussed, quantitatively. Various parameters to be considered in designing are investigated in detail. The predistortion technology proposed is based on the lookup-table method using the input and output signal envelopes and can operate independently from the baseband block. By omitting adaptative predistortion for amplitude/phase modulation and integrating the main controlling functions on a single CMOS integrated-circuit chip, the predistortion capability has been realized in a PA module. The PA module has a power-added efficiency (PAE) of 48% at an output power of 27.5 dBm. This PAE is very high in comparison with that of the conventional PA module for N-CDMA.

There is a controversy on the effects of physiological levels of glucocorticoids on natural killer (NK) cytotoxity. Therefore, the effects of exogenously administered dexamethasone on NK cytotoxity in 8-week-old male, Fischer 344 rats were studied. We suppose that the reason for the controversy is insufficient sensitivity of the ordinal radioactive chromium-release assay for normal healthy subjects or animals. Therefore, we developed a new index, a resistance to artificial immunosuppressor, cyclosporine A (CsA) using rat NK activity as an indicator, and named this index, increased resistance to immunosuppressor (IRIS). After some basic, characterizing studies, authors confirmed the fact that continuous doses of dexamethasone (DEX) attenuated NK suppression of CsA. In protocol 4, 18 rats were randomly divided into three groups: the first (DEX + CsA) was injected for 5 days with 0.1 mg DEX/kg/day and a single dose of CsA on the final day, intraperitoneally; the second (SAL + CsA) was treated with an equal volume of saline and CsA; the third (DEX + SAL) was treated with DEX but not CsA. The IRIS in NK activity was increased significantly (P < 0.01) with 5 days injection of DEX. These results demonstrated that physiological, and continuous dosage of glucocorticoids stimulated IRIS in NK activity in rats, and this suggests that appropriate stimuli through the hypothalamic-adrenal axis might be acting, at least, as a defence against immune collapses or dysfunctions.

Track-edge noise has been analyzed to clarify track-edge noise mechanisms. Edge noise arises from two different regions: the bit edge where the magnetization direction is opposite to the previously dc-erased direction and the magnetic transition edge. The edge noise at low density is mainly due to the magnetic distribution at the bit edge. The transition edge noise increases with increasing recording density, and it becomes dominant at high-recording density for an oriented medium. On the other hand, the transition edge noise is almost constant with increasing recording density for an isotropic medium.

Track-edge noise in a written track and a partially dc-erased track was analyzed to clarify the edge noise properties of a side-erased band. It was found that the track-edge noise power and its noise components in a partially erased track are equal to those in a written track. The track-edge noise power in a side-erased band is the summation of the transition-edge noise power of old track, the overwritten track, and the bit-edge noise power.

The effects of recording heads on off-track noise characteristics were examined. It was found that an FeTaN head with a narrow gap and high Bs was very effective for decreasing both on-track noise and off-track noise, in com- parison with a NiFe head with a narrow gap or a merged- type NiFe head with a wide gap. It was also confirmed that, according to readback waveform analysis and MFM images observation, the fluctuations of the magnetic transition in track-edge regions for magnetic patterns recorded by the FeTaN head were much smaller than for those recorded by the merged-type NiFe head with a wide gap. It will become increasingly important to improve recording heads as their track width becomes narrower.

The effect of remanent magnetic flux density (B/sub r/) and magnetic layer thickness (/spl delta/) on offtrack noise characteristics in Co-Cr-Ta alloy thin films is investigated. It has been found that decreasing the value of B/sub r/ is a more effective method of improving offtrack noise characteristics than decreasing the value of /spl delta/. Offtrack noise is shown to be due to the fluctuations in the amplitude of readback waveforms, fluctuations which are caused by fluctuations in magnetic transition amplitude. It was observed, using a magnetic force microscope, that lower B/sub r/ media had sharp boundaries at the track edge regions and the magnetization was more uniform, compared with those of higher B/sub r/ media.

The shielded magnetoresistive (MR) head offtrack profile shows a wide output plateau which follows the conventional offtrack roll off curve. The authors investigated the origin of the unique offtrack characteristics and their influence on crosstalk signal-to-noise-ratio (SNR), based on experimental and magnetic calculation results. In the measurement, 8- mu m track-width MR heads, consisting of a pair of 100- mu m shields and a trilayered MR element between shields, were used. The plateau width is close to the shield width. The output in the plateau region is the sum of the contributed outputs from individual tracks under the shield. Therefore, this output can severely reduce the crosstalk SNR when the MR head includes several tracks under the shield. Magnetic calculation shows that the magnetic flux from the recorded track to the MR element through the shields can produce the output at the plateau region. Further examination shows that crosstalk SNR is improved by increasing the shield thickness and/or by decreasing the shield width. Therefore, to realize high track density, shield optimization is important. >

Methods of theoretical simulations of noncontact atomic force microscopy in liquids have been developed. Though there are several difficult issues for the theoretical simulations in liquids, the authors introduce here the simulation methods for the cantilever oscillation in liquids and the tip-sample interaction force mediated by water molecules. As for the cantilever motion, a very efficient numerical method is proposed which solves the oscillation of the elastic beam cantilever and fluid dynamics simultaneously. The results reproduce fairly well the resonant curve and related properties of the Si beam cantilever. As for the simulation of the tip-sample interaction force in water, classical molecular dynamics (MD) method is adopted in the present work. The case study by MD for the mica surface in water revealed new features that appeared in the three-dimensional force map.

Media noise characteristics of CoCrTa/FeSiAl perpendicular magnetic recording media were investigated to clarify the effects of underlayer characteristics such as crystalline orientation, surface roughness on the medium noise of double-layer media. A strong correlation was found between maintaining a smooth underlayer surface and attaining a low level of medium noise. Insertion of a Cr layer between the glass substrate and the FeSiAl underlayer and sputtering the underlayer at low Ar-gas pressure are effective in maintaining its surface smoothness. These measures reduce medium noise.

The read/write characteristics of a double-layered perpendicular magnetic recording medium were examined by using a combination of a single-pole-type write head and a magnetoresistive read head (SPT write / MR read), and a conventional merged ring type inductive / MR head (RT write / MR read). By differential equalization of the reproduced voltage, the STP/MR head combination had high density recording capability, compared with the RT/MR head. Bit error rate through PR(1) signal processing was evaluated for the SPT/MR head combination and the RT/MR head. It is clarified that bit error rate for the SPT/MR head combination and the RT/MR head. The bit error rate less than 10-6 at 3 Gb/inch2 was obtained for the SPT/MR head combination.

Subjects for recording densities of 10Gbt/in2 - 30Gb/in2 are discussed, for longitudinal and perpendicular recording. Read-write specifications are estimated for their high recording densities. Reproducing outputs above 1mVpp/μm for magnetic heads are required. Correlation between magnetic media properties and recording densities are calculated for 10 - 30 Gb/in2 densities. Noise characteristics subjects and thermal instabilities are discussed for longitudinal recording media and perpendicular recording media.

The effect of the residual magnetic flux density (Br) on the media noise in Co-Cr-Ta alloy thin films has been investigated. Longitudinal media with higher Br and thinner magnetic layer have superior media noise to signal ratio compared to media with lower Br (below 2,000 G) and thicker magnetic layer under the constant Br δ, where δ is the magnetic layer thickness. It was revealed that media noise is proportional to fluctuations in the magnetic transition region according to analysis of the readback waveform. Furthermore, ferrite media exhibits an excellent possibility for use as a low noise media at high recording densities.

The recording noise of sputtered Co alloy media at high recording density was studied with readback waveform. High noise power of longitudinal recording media at high recording density was correlated to the fluctuation of magnetic transition region. In perpendicular recording media, in contrast, the fluctuation of magnetic transition region was small even at high recording density, which leads to low noise power.

This paper describes the relation between pass-wear durability and medium tribological factors, including surface roughness, mechanical and chemical properties of CoCr and overcoat layers, lubrication and medium flexural rigidity. CoCr and overcoat layers were sputter deposited on various base films. Pass-wear durability was evaluated by using a single-sided 3.5″ flexible disk drive. CoCr wear strongly depends on the surface roughness and mechanical strength. The wear resistance is proportional to the tensile strenght of the CoCr films, in accordance with Archard's adhesive wear theory. The pass-wear durability is improved by surface treatments, including lubrication and overcoat application. A surface active agent is effective to increase the pass-wear durability, because lubricant affinity to the overcoat surface is improved. Furthermore, pass-wear durability is strongly influenced by medium flexural rigidity. By optimizing these tribological factors. sufficient pass-wear durability for practical use (more than 10 million passes) can be obtained.

Ferrite thin film disks using electroless-plated Ni-P substrates have been prepared. The practicability of attaining these disks at areal densities above 4.7 X l04bits/mm2(28 K-FRPI X 1100 TPI) has been confirmed from the following view points: read/write and error characteristics, signal-to-noise ratio (SNR), and wear durabilities. Over -20 K-FRPI, noise level decreases were found. As a result, more than SNR 35 dB at 40-50 K-FRPI were attained. Practical feasibilities were also confirmed at 40-50 K-FRPI. In wear durability, 20 000 contact-start-stop operations were achieved.

Three-dimensional external bit fields emanating from single and multiple magnetic transitions with a finite track width have been calculated. The magnetic field interferences between tracks have been also simulated. The results show that the fields have a large component in the track width direction near the transition edges. This contributes to field extension in the neighboring track direction. The amount of extension decreases with bit density increase. The results of our calculations are backed up by Lorentz microscopy observation of films in which bit fields are transcribed.

A simulation model for vertical type multiturn thin film head was established, which included all the basic parameters determining its cross-section structure. Using this model, effects of major parameters on the write field were analyzed and discussed.

A new method of observing external bit fields emanating from recorded media is proposed. Fields are magnetically transcribed to a magnetic film located some distance from a recording surface and are observed by means of Lorentz microscopy. Some observed field patterns are shown, and the magnetic flux flows are analyzed.

Magnetic anisotropies were investigated for CoCr perpendicular magnetic films on grooved structure substrates (pitch length 2.1 mu m) prepared by CF/sub 4/-reactive-ion etching. Perpendicular magnetic anisotropy decreases in the region where groove depth GD >650 A. The reduction is due to the inclination of the crystal growth axis on the groove surface. In-plane magnetic anisotropy, K/sub u///, strongly depends on GD and saturation magnetization M/sub s/. In a region of large GD and large M/sub s/, Ku/sub /// is mainly due to shape anisotropy. In a region of small GD and small M/sub s/, K/sub u/// is caused by perpendicular magnetic anisotropy, in addition to shape and magnetorestrictive anisotropy. >

A new preparation method for γ-Fe 2 O 3 thin film recording media has been established. Using sintered Fe 3 O 4 plates as targets, Fe 3 O 4 films are directly formed over wide sputtering condition ranges through R.F. sputtering in argon atmosphere. Planar magnetron sputtering has successfully been attempted to attain sputtering rates higher than 2,000 A/min. Co, Cu doped γ-Fe 2 O 3 thin film disks have been prepared by the present method. Their read/write characteristics were experimentally evaluated using a conventional ferrite head with 20 μm core width, which has shown D -6dB density as high as 1140 BPM (bits per millimeter).

A flexible disk of continuous ferrite thin film has been prepared. Ferrite thin film media have been formed on flexible polyimide substrates through direct radio frequency (RF) sputtering deposition of Co, Cu doped Fe 3 O 4 films. The D -6 dB density for the ferrite thin film, 18 K-FRPI, which is significantly higher than the 7 K-FRPI value for conventional media, was obtained with a 1.0 μm gap length ferrite head.

金沢大学理工研究域数物科学系, Pass wear resistance of sputtered CoCr perpendicular flexible disks has been investigated. The disk was composed of CoCr film on a heat-resistant base film, a protection layer, and lubricant. The pass wear durabilities were evaluated for a conventional double-sided 3.5-in drive. It was found that the scratch depth (SD) per load force (LF) depends on preparation conditions, and that the CoCr film hardness is related to pass wear durability. SD/LF values range from 0.2 to 0.3 for CoCr films without a protective layer. With a protective layer and lubricant, the range of SD/LF values varies from 0.2-0.3 to 0.1-0.3. The disk hardness, especially for small SD/LF media, has been improved. A pass wear durability of 30 million passes was attained for a disk having SD/LF = 0.1.

Magnetic properties for sputtered CoCrTa films (18 at.% Cr and 2.0-3.0 at.% Ta), which were deposited under various background pressures P/sub i/, and argon sputtering pressures, P/sub Ar/, have been examined. The perpendicular anisotropy field H/sub k/ for CoCrTa films maintains high values of 5-6 kOe in a wide range of P/sub i/ and P/sub Ar/, as compared with that for CoCr films. In order to optimize Ta composition, magnetic properties and crystalline microstructures for Ta additive content (0-4.0 at.%) have been investigated. H/sub k/ and perpendicular coercivity H/sub c perpendicular to / increase with increasing Ta concentration above 2.0 at.% Ta. C-axis orientation is improved by adding Ta to CoCr films. However, above 3.0 at.% Ta, H/sub c perpendicular to / steeply decreases and domain wall motion is observed, owing to the increase in crystalline grain size. The appropriate Ta composition is 2.0-3.0 at.%. >

Corrosion rate activation energy ΔE has been evaluated by measuring electrical resistance increase due to corrosion for CoCr (0 ∼ 26 at%Cr) film stripe patterns under exposure to various temperatures and 85% relative humidity. A relation of corrosion layer thickness X to Cr density x, test temperature T and test time t were obtained. The relation was expressed by X = C \cdot \exp(-\gamma \cdot x) \cdot \exp(-\Delta E/k T)\cdot \log(t+l) , where K, γ and C are the coefficient and Boltzmann's constant,respectively. ΔE values for CoCr films (0∼ 26 at%Cr) depend upon Cr density and preparation conditions. These values ranged from 0.075 to 0.32 eV. Corrosion characteristics are varied by not only film microstructure, but also to Cr atom distribution in crystalline matrix even for films with same Cr density.

Magnetic properties and crystalline structures for sputtered FeTi films (0-40 at% Ti in composition), have been examined. The film structures were divided into three regions, bcc phase, transition region from bee to amorphous phase, and amorphous phase. In the transition region (15-18 at% Ti) from bcc to amorphous phase, FeTi films with perpendicular magnetic anisotropy were found. Saturation magnetization, magnetic anisotropy field, and perpendicular coercivity for a typical FeTi film (16.8 at% Ti) prepared in the transition region were 300 emu/cc, 2.7 kOe, and 710 Oe, respectively. Crystalline microstructures for FeTi films with perpendicular magnetic anisotropy are composed of amorphous phase and isolated pillar or pin-like crystalline grains (200-500 A) with bcc phase surrounded by the amorphous phase. Therefore, the origin of perpendicular magnetic anisotropy on FeTi films is mainly attributed to the grains shape anisotropy.