Quantitative current measurements using scanning magnetoresistance microscopy

We have demonstrated the capability of scanning magnetoresistance microscope (SMRM) to be used for quantitative current measurements. The SMRM is a magnetic microscope that is based on an atomic force microscope (AFM) and simultaneously measures the localized surface magnetic field distribution and surface topography. The proposed SMRM employs an in-house built AFM cantilever equipped with a miniaturized magnetoresistive (MR) sensor as a magnetic field sensor. In this study, a spin-valve type MR sensor with a width of 1 microm was used to measure the magnetic field distribution induced by a current carrying wire with a width of 5 microm and a spacing of 1.6 microm at room temperature and under ambient conditions. Simultaneous imaging of the magnetic field distribution and the topography was successfully performed in the DC current ranging from 500 microA to 8 mA. The characterized SV sensor, which has a linear response to magnetic fields, offers the quantitative analysis of a magnetic field and current. The measured magnetic field strength was in good agreement with the result simulated using Biot-Savart's law.     

Fretting wear of Ti-48Al-2Cr-2Nb

An investigation was conducted to examine the wear behavior of gamma titanium aluminide (Ti-48Al-2Cr-2Nb in atomic percent) in contact with a typical nickel-base superalloy under repeated microscopic vibratory motion in air at temperatures from 296–823 K. The surface damage observed on the interacting surfaces of both Ti-48Al-2Cr-2Nb and superalloy consisted of fracture pits, oxides, metallic debris, scratches, craters, plastic deformation, and cracks. The Ti-48Al-2Cr-2Nb transferred to the superalloy at all fretting conditions and caused scuffing or galling. The increasing rate of oxidation at elevated temperatures led to a drop in Ti-48Al-2Cr-2Nb wear at 473 K. Mild oxidative wear was observed at 473 K. However, fretting wear increased as the temperature was increased from 473–823 K. At 723 and 823 K, oxide disruption generated cracks, loose wear debris, and pits on the Ti-48Al-2Cr-2Nb wear surface. Ti-48Al-2Cr-2Nb wear generally decreased with increasing fretting frequency. Both increasing slip amplitude and increasing load tended to produce more metallic wear debris, causing severe abrasive wear in the contacting metals.     

Profile of polyunsaturated fatty acids produced by Thraustochytrium sp. KK17-3

More than 300 strains of microorganisms producing polyunsaturated fatty acids (PUFA) were newly isolated from coastal seawater in the Seto Inland Sea and around Iriomote Island, Japan, by the baiting method. The profiles of PUFA from docosahexaenoic acid (DHA)-producing strains could be classified into four types. A strain, named KK17-3, was chosen for further study owing to its high DHA content (52.1% of total fatty acid) and wide range of PUFA (76.1%) including arachidonic, eicosapentaenoic, and docosapentaenoic acids as well as DHA. Glucose and tryptone were the optimal carbon and nitrogen sources, respectively, in a medium with salinity at 75% that of seawater. The PUFA contents in polar lipids (22.1% of total lipid), in which the DHA content was 39.3%, were higher than those in neutral lipids and glycolipids. Molecular phylogenetic analysis of 18S rRNA gene sequences showed KK17-3 to be a thraustochytrid. It also was observed to possess a life cycle composed of vegetative cells without successive bipartition, zoosporangium, and zoospore stage. Classification by the chemotaxonomic criterion based on PUFA compositions also supported this assignment.     

Optical guiding of intense laser pulses by fast Z-pinch discharge

We have proposed the optical guiding of intense laser pulses by fast Z-pinch for channel-guided laser wakefield acceleration (LWFA). The method has been developed based on capillary discharge-pumped X-ray laser technique. A discharge through preionized helium gas driven by a current of 4.8 kA with a rise time of 15 ns proved able to produce a uniform guiding channel with good reproducibility, less than the time jitter of 1.8 ns. The observed guiding channel formation process was corroborated by 1D-MHD simulation. With this new guiding method, an intense Ti-sapphire laser pulse (λ = 790 nm, 2.2 TW, 90 fs, 1 × 10¹⁷ W/cm²) was transported through the channel over a distance of 2 cm, corresponding to 12.5 times the Rayleigh length. © 2001 Scripta Technica, Electr Eng Jpn, 136(3): 19–27, 2001     

Reactive Infiltration of Aluminum into Molybdenum Disilicide Preform

Aluminum has been reactively infiltrated into a molybdenum disilicide preform with relative densities of 40% and 85%. The resultant compact is found to contain Mo(Al,Si)₂ particles surrounded by aluminum metal; 14 to 18 at.% of aluminum reacted with MoSi₂ irrespective of the infiltration temperature and time.     

PARTICIPATORY ACTION RESEARCH FOR ENVIRONMENTAL HEALTH: ENCOUNTERING FREIRE IN THE URBAN BARRIO

ABSTRACT: The community‐based approach to health research and intervention is a model of inquiry rooted in Freire's participatory action research (PAR). We need to show, in concept and practice, what it is about PAR that may be well suited for the types of health issues we encounter in inner‐city environments. What type of learning results, how does this respond to particular health issues in the urban context, and what are the particular challenges faced in translating Freire's model into today's urban setting? To investigate these questions, we describe a recent PAR project in Southeast Los Angeles, California—an area known to some as “Asthmatown.” One salient finding of the research is that PAR allows the integration of complex and multiple forms of knowledge, and this is a necessary response to the complex and multiplex nature of cumulative impacts. There are challenges to translating the model to the urban setting, however, such as the difficulties of participation in today's urban milieu. The research leads to some lessons for practitioners, such as the need to build “constant” elements into PAR projects. Lastly, we reflect on implications of this model for institutional reform.     

Determination of unsaturated fatty acid composition by high-resolution nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the ¹H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the ¹³C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from ¹³C NMR were in better agreement with those from GC than were the results obtained by the ¹H NMR method.     

The High-Resolution X-Ray Microcalorimeter Spectrometer, SXS, on Astro-H

The science and an overview of the Soft X-ray Spectrometer onboard the STRO-H mission are presented. The SXS consists of X-ray focusing mirrors and a microcalorimeter array and is developed by international collaboration lead by JAXA and NASA with European participation. The detector is a 6×6 format microcalorimeter array operated at a cryogenic temperature of 50 mK and covers a 3′×3′ field of view of the X-ray telescope of 5.6 m focal length. We expect an energy resolution better than 7 eV (FWHM, requirement) with a goal of 4 eV. The effective area of the instrument will be 225 cm² at 7 keV; by a factor of about two larger than that of the X-ray microcalorimeter on board Suzaku. One of the main scientific objectives of the SXS is to investigate turbulent and/or macroscopic motions of hot gas in clusters of galaxies.     

Innovative collagen nano-hydroxyapatite scaffolds offer a highly efficient non-viral gene delivery platform for stem cell-mediated bone formation

The ability of nano-hydroxyapatite (nHA) particles developed in-house to act as non-viral delivery vectors is assessed. These nHA particles are combined with collagen to yield bioactive, biodegradable collagen nano-hydroxyapatite (coll-nHA) scaffolds. Their ability to act as gene-activated matrices for BMP2 delivery is demonstrated with successful transfection of mesenchymal stem cells (MSCs) resulting in high calcium production.