Yuji C. Sasaki

We demonstrated dynamical observation of an individual nanocrystal in supercooled liquid water with the guidance of x-ray diffracted spots from the nanocrystal itself. This new system, which we call diffracted x-ray tracking, monitored small Brownian motions (D=0.68 mrad(2)/s at 233 K) of a single nanoparticle in real time and real space.

Fluorescent x-ray interference patterns have been observed from monolayers of both a metal-containing protein (ferritin) and a nonmetal-containing protein [bovine serum albumin (BSA)] bound on a gold substrate. These interference patterns have been used to determine structure data. The nonmetal-containing protein was first reacted with metal ions by means of a chelate compound to place the necessary chromophore in the molecule. The size of the ferritin core measured by a scanning electron micros

Time-resolved dynamical x-ray imaging of individual DNA molecules with picometer-scale precision is demonstrated for the first time. Diffracted x-ray tracking (DXT), a single-molecule experiment with x rays, monitors the rotating motions, rather than the translational motions, of a labeled nanocrystal. DXT can obtain information about the dynamics of single molecules through a quantitative analysis, since the signals from DXT are independent of the chemical conditions.

For high-density recording tape, NanoCAP was developed using co-precipitation and nitridation treatment in an NH/sub 3/ gas atmosphere. Each particle has a spherical shape with a diameter of about 17 nm and a core-shell structure. The core and shell mainly consist of the Fe/sub 16/N/sub 2/ and oxides containing Al and Y, respectively. The saturation magnetization and the coercive force are 85.5 A/spl middot/m/sup 2//kg (85.5emu/g) and 227 kA/m (2850 Oe), respectively. The coercive force is a hig

Group II chaperonins play important roles in protein homeostasis in the eukaryotic cytosol and in Archaea. These proteins assist in the folding of nascent polypeptides and also refold unfolded proteins in an ATP-dependent manner. Chaperonin-mediated protein folding is dependent on the closure and opening of a built-in lid, which is controlled by the ATP hydrolysis cycle. Recent structural studies suggest that the ring structure of the chaperonin twists to seal off the central cavity. In this stu

We report a systematic study of ferromagnetic resonance (FMR) on thin films of the ferromagnetic semiconductor GaMnAs grown by low temperature molecular beam epitaxy. Pronounced shifts of the FMR line are observed towards fields above and below the g=2.00 resonance position for the magnetic field orientations perpendicular and parallel to the plane of the layer. At higher temperatures these shifts decrease rapidly as the Curie temperature is approached, converging on the g=2.00 resonance positio

We demonstrated analysis of the nondestructive depth profile near the surface of As ion-implanted Si substrate by using the refracted x-ray fluorescence method. Experimental results show that the angular distribution of the measured x-ray fluorescence is dependent on the surface roughness of the substrate.

Fe nanocrystalline films were prepared by the gas-deposition method (GDM). The films were composed of small particles and their aggregates. With an increase of pressure difference between an evaporation chamber and a deposition chamber, the grain size is slightly reduced and lower coercivity is realized. The Mössbauer spectra consisted of a crystalline component (α-Fe) and a boundary component with a hyperfine field of 310 kOe; no oxide subspectrum was observed. Magnetizations of the samples are

A peculiar angular pattern is observed from K\ensuremath{\alpha}-fluorescent x rays emitted from a Zn monoatomic layer in a Langmuir-Blodgett film onto a Au substrate. A pattern similar to Young's fringe is monitored with a non-energy-dispersive two-dimensional detector (imaging plate), and is quantitatively measured by scanning the slit with an energy-dispersive detector (pure Ge detector). The fringes are in close agreement with a theoretical estimate based on the interference among transmitte