Toshiyuki Adachi

Capacitation-related changes in antigen distribution on mouse sperm heads and its relation to fertilization rate in vitro

The anti-mouse sperm monoclonal antibody OBF13 did not react with fresh epididymal sperm. However, when sperm were incubated in a culture medium capable of inducing capacitation, the entire head of the sperm began to react with this antibody. This change of reactivity was not observed when sperm were incubated in a Ca2+-free medium. The change of the reactivity to the antibody was studied in relation to the fertilizing ability of sperm as measured in an in vitro fertilization system; a significant correlation was observed between the appearance of head-stained sperm and fertilization rate.

Glow discharge produced amorphous silicon solar cells

Abstract A series of basic investigations on the glow discharge produced amorphous silicon (GDa-Si) and its interface properties aimed for the low cost solar cells has been carried out. The fabrication technique to make wide area and uniform films is presented, and the optical and photovoltaic properties of GDa-Si are also discussed. In the present stage of our experiments, a conversion efficiency of as high as 4.5% has been achieved in an ITO/p i n cell for AMI sunlight. This type of solar cells may have a possibility to improve their photo-voltaic performances by the optimum design on the solar cell structure.

Inconsistent reactivity of an anti-sperm monoclonal antibody and its relationship to sperm capacitation

An anti-sperm monoclonal antibody was developed from female C57BL/6 mice immunized with epididymal sperm from a syngeneic male mouse. Immunofluorescence staining revealed that the antibody did not react to fresh epididymal sperm but attached to the capacitated sperm found in the peri-vitelline spaces of the ova. When the antibody was applied to sperm incubated in vitro, variously stained sperm were observed. It was presumed that the antigenic site detected by the antibody was hidden in the fresh epididymal sperm and was spread from the acrosomal cap region to the entire head during the capacitation process.

Field-ion microscopy of GaAs and GaP

Abstract Clean surfaces of GaAs and GaP were studied by field-ion microscope (FIM). Field-ion images with ordered surfaces were first obtained in pure hydrogen, neon-50% hydrogen and pure neon gases at 78 K, by using channeltron electron multiplier arrays (CEMA). The field-ion images of GaAs were quite similar to those of GaP with respect to the surface structure and the image contrast. They showed the anisotropies of the ion emission and the surface structure between the [111] and [ 1 1 1 ] orientations. Ring steps expected from a spherical surface were observed on the (111) and {100} planes, but not on the [ 1 1 1 ] and {110} planes. The regional brightness of the FIM patterns was discussed in terms of the Knor and Muller model and the atomic and electronic structures of the surface. The image field of these crystals was much lower than that of metals usually used in FIM. For example, the image field strength for the hydrogen and GaAs system was about 1.1 V/A. The reduction of the field necessary to image was also discussed in terms of the field penetration effect.

Eutectic reaction of gold thin-films deposited on silicon surface

Abstract Eutectic reaction of gold thin-films deposited on silicon surfaces have been studied using a field-ion microscope (FIM) and a time-of-flight atom probe FIM. The heat treatment for the eutectic reaction was performed at about 400–1000 °C for a few seconds. Amount of 0.7–100 Au monolayers were deposited on a Si tip surface, and Au rods embedded in the Si substrate are formed in eutectic alloys near the surface after heating. The size of the Au rods in these eutectic alloys is proportional to the amount of deposited Au, while the number of rods increases with decreasing amount of deposited Au. These eutectic alloys are always covered by an intermixed layer. No crystalline silicide phases were observed. The atom probe analysis showed that the grown Au rods contain no Si atoms. On the other hand, it showed that the Si phase contains a very small amount of Au atoms.

Effect of glucose and phloretin-2′-β-D-glucose (phloridzin) on in vitro fertilization of mouse ova

The fertilization ratio of mouse ova in vitro decreased when glucose concentration in the medium was lowered. However, the addition of phloretin-2′-β-D-glucose (phloridzin), known as a glucose uptake inhibitor, restored the fertilization ratio back to the control level. The glucose moiety of the phloridzin seemed to be responsible for this effect.

Direct comparison of performances of TOF atom‐probe FIM in the linear and energy‐compensated mode

A direct comparison of the performances of the time‐of‐flight (TOF) atom‐probe mass spectrometer in the linear and the energy‐compensated mode has been carried out using our newly constructed combined‐type TOF atom‐probe field ion microscope. The detectability and the mass resolution were measured using the W(011) plane and the Mo(011) plane, respectively. The results suggest that in the energy compensated‐type mass spectrometer, the use of an einzel lens for focusing the ion beam (called a ‘‘focusing energy compensated‐part’’ in the text) is an effective way to increase the transmittance of ions through the deflector system without lowering mass resolution. It is suggested that this type of TOF atom probe is the best.

An atom-probe analysis of LaB6(001) plane

A layer-by-layer analysis of the lanthanum hexaboride (LaB6) (001) region was carried out by using an atom-probe field ion microscope (FIM) in order to clarify the field evaporation process on the (001) plane. The consideration of the results and the (001) plane surface atom model suggest that only boron atoms show in a noble gas ion image of the LaB6 (001) plane.

Field evaporation end form at 4.2 K

Abstract Field evaporation end forms of tungsten and iridium have been observed at several temperatures. At 21 K and above, the surfaces contain atoms in metastable positions which give rise to decorated zone lines, double plane edges and superstructures, but at 4.2 K these are scarcely observed. These results imply that at the higher temperatures an edge atom may migrate to a surface site before it evaporates, while at 4.2 K the edge atom may evaporate without surface migration. A considerable part of the migration energy is probably due to a field induced dipole-dipole repulsion.

Resolution of the Field-Ion Microscope

The resolution of the field-ion microscope image for tungsten surface is measured as a function of temperature, tip curvature and dimension of imaging gas molecules. The resolutions obtained for He gas are slightly higher than those calculated from the Muller and Tsongs theory using the diameter of outer orbital for the dimension of the imaging gas molecules, and for Ne and H2 are in agreement with the theoretical ones. The nearest neighbour, 2.74 A, atom chains across the edges of {112} planes can be resolved at 120 K with He, but on the other net planes it can never be resolved even at 21 K. A reason why the experimental resolutions are different among each net plane is discussed.