Yoshimasa Nihei

THE EFFECTS OF NANOPARTICLES ON MOUSE TESTIS LEYDIG CELLS IN VITRO

We have indicated the possibility that nanoparticles such as diesel exhaust particles (DEP) and titanium dioxide (TiO(2)) may impair the male mouse reproductive system. In this study, to evaluate the direct effect of nanoparticles on testis-constituent cells, we examined the effect of DEP, TiO(2) and carbon black (CB) on mouse Leydig TM3 cells, the testosterone-producing cells of the testis. The uptake of three nanoparticles into Leydig cells was detected using transmission electron microscopy (TEM) or field emission type scanning electron microscopy/energy-dispersive X-ray spectroscopy (FE-SEM/EDS). We examined the cytotoxicity and the effect on gene expression by treatment with nanoparticles. TiO(2) was more cytotoxic to Leydig cells than other nanoparticles. The proliferation of Leydig cells was suppressed transiently by treatment with TiO(2) or DEP. The expression of heme oxygenase-1 (HO-1), a sensitive marker for oxidative stress, was induced remarkably by treatment with DEP. Furthermore, CB and DEP slightly increased the gene expression of the steroidogenic acute regulatory (StAR) protein, the factor that controls mitochondrial cholesterol transfer. In this study, we found that DEPs, TiO(2) and CB nanoparticles were taken up by Leydig cells, and affected the viability, proliferation and gene expression. The patterns were unique for each nanoparticle.

DEVELOPMENT OF AN ION AND ELECTRON DUAL FOCUSED BEAM APPARATUS FOR THREE-DIMENSIONAL MICROANALYSIS

We are developing a novel three-dimensional (3D) microanalysis method by means of successive cross-sectional Auger mapping. In this method, a 3D elemental map will be obtained by repetition of the cross-sectioning of a sample using a gallium focused ion beam (Ga FIB) and Auger mapping of the cross section using an electron beam (EB). On the basis of this concept, an ion and electron dual focused beam apparatus was developed by combining a Ga FIB and a mass spectrometer with a scanning Auger microprobe. In this paper, we describe the concept and instrumentation of the dual focused beam apparatus. Two types of preliminary experiments; i) successive cross-sectioning of a microparticle (6.8 µm) and ii) successive cross-sectional sample current imaging of a bonding wire of an IC, demonstrated the capability to create flat analytical surfaces favorable for the 3D analysis with arbitrary shape and heterogeneity.

Differential Photoelectron Holography: A New Approach for Three-Dimensional Atomic Imaging

We propose differential holography as a method to overcome the long-standing forward-scattering problem in photoelectron holography and related techniques for the three-dimensional imaging of atoms. Atomic images reconstructed from experimental and theoretical Cu 3p holograms from Cu(001) demonstrate that this method suppresses strong forward-scattering effects so as to yield more accurate three-dimensional images of side- and backscattering atoms.

Quantitative analysis by submicron secondary ion mass spectrometry

In order to apply secondary ion mass spectrometry (SIMS) to quantitative analysis of submicron areas, we made a high‐spatial resolution SIMS (submicron SIMS) by combining a focused metal ion beam, a plane‐focusing mass spectrometer, and a multichannel parallel detection system. A 35 kV, 100 pA beam with diameter on the sample of <0.1 μm was used. During measurements, this high‐current density ion beam can destroy the sample with a large sputtering rate when slowly rastered. This causes rapid changes in both absolute and relative intensities of secondary ions. In our system, a 120‐channel parallel detector covers the 1:2 mass range of m/e dispersion. By using this submicron SIMS, quantitative factors in the analysis of microstructures on the surface were investigated. Sputtering yield and, consequently, secondary ion intensity depend largely upon the angle between the primary beam and the sample surface just under the beam irradiation; such topographic effects distort the quantitative results. In order to ...

Photoelectron diffraction effects in XPS angular distributions from GaAs(110) and Ge(110) single crystals

Abstract Angular distribution measurements of XPS intensities have been made for various spectral lines from GaAs(110) and Ge(110) single-crystal surfaces. Observed angular distribution curves (ADCs) showed steep intensity variations and sharp peaks due to X-ray photoelectron diffraction (XPED) phenomena. The effects of the type of transition process (photoelectron or Auger), electron kinetic energy and crystal structure on the XPED patterns were examined. Considerably different ADC patterns were observed for high-energy photoelectrons and Auger electrons and for low-energy photoelectrons. ADCs for Ga 3d, As 3d and Ge 3d showed almost the same patterns for scans of the type [110] → [100] → [1 1 0], but they showed substantially different patterns for [110] → [11 1 ] → [00 1 ] scans. These features correspond well with the structural characteristics of GaAs and Ge crystals. A discussion of the applicability of XPS angular distribution measurements to the geometric analysis of crystal surfaces is presented.

Angular resolved x-ray photoemission study of defects induced by ion bombardment on the TiO2 surface

Angular resolved X-ray photoelectron spectroscopy was used to study single crystal TiO2 surfaces where defects (that is Ti3+ ions) were created by Ar+ ion bombardment. An estimate of the thickness of the disordered layer was obtained by an analysis of the attenuation of the oscillations in the polar photoelectron diffraction patterns of the Ti 2p signal. The intensity of the Ti3+ /Ti4+ signal ratio as a function of the electron collection angle was analyzed by means of simple structural models. The best agreement of calculations and experiment was obtained with a model which assumes that partially reduced titanium is present mainly in the subsurface region.

High spatial resolution 3D analysis of materials using gallium focused ion beam secondary ion mass spectrometry (FIB SIMS)

Abstract The sharpness and high density of focused ion beams (FIB) enable micromachining of materials. When a gallium FIB is used as a primary beam for secondary ion mass spectrometry (SIMS), 2D analysis with submicron resolution is easily achieved. In situ combination of micromachining and high spatial resolution analysis brings a new field of microbeam analysis of materials. The gallium FIB SIMS apparatus was developed by combining a FIB and a plane-focusing mass analyzer equipped with a multichannel ion detection system (120 channel). Both a high-spatial resolution and a large sputtering rate are realized. Multielement parallel detection has a great advantage for obtaining precise distribution of elements in microstructure samples. In this paper, a new type of 3D analysis and depth profiling technique is introduced and applied to single particle analyses. A spatial resolution of 50 nm for 3D analysis and a depth resolution up to 5 nm were realized by using these methods.

Charge transfer effects on the chemical shift and the line width of the CuKα X-ray flourescence spectra of copper oxides

Abstract It has been found that in the X-ray flourescence (XRF) spectra of CuO the chemical shift of the Cu Kα 1 is approximately the same as that of Cu 2 O, and also that the line width of the Cu Kα 1 , of CuO, is anomalously narrow in spite of the fact that this oxide has an unpaired electron in the 3 d orbital. These experimental facts are successfully interpreted on the basis of the configuration mixing of the initial and final states of Kα X-ray emission. The 1 s −1 and 2 p −1 hole states are not the pure 3 d 9 state but are mixed with the 3 d 10 O 2 7 minus ;1 state due to charge transfer of one of the O 2 p electrons to the 3 d −1 hole. Thus the valency of thecore hole states of CuO is mainly Cu(I), consequently the Cu(II) Kα chemical shift becomes close to that of Cu(I). Also since the 3 d −1 hole is well screened by the O 2 p electron the multiplet splittings, due to exchange interaction between 3 d −1 hole and Cu core hole (1 s −1 or 2 p −1 ), were not observable.

Sc Kα, and Kβ X-ray fluorescence spectra

Abstract Scandium Kα 1,2 , Kα ″, Kβ 1,3 , Kβ ″, and Kβ 5 X-ray fluorescence spectra were measured with a two-crystal X-ray fluorescence spectrometer for Sc(metal) and various scandium compounds. The following have been clarified. (i) The Kβ ″ satellite was strong for ScF 3 but weak for Sc 2 O 3 . The chemical effects on the intensity and energy of the Kβ ″ have been interpreted for ScF 3 and Sc 2 O 3 by the electronic structure calculations of DV- Xα molecular-orbital method. The Kβ ″ is assigned to the electron transition from an antibonding molecular orbital which is formed between Sc 3 p and ligand 2 s to the ls −1 hole. (ii) The transition assignment of Kβ 5 i.e. the electric quadrupole transition from 3 d to 1 s , has been found false for Sc. The Kβ 5 , has been assigned to the electric dipole transition from valence molecular orbitals to the 1 s −1 hole. (iii) The Kα ″ satellite of ScF 3 was found to be significantly weaker than those of other Sc compounds, whereas the Kβ ″ satellite of ScF 3 stronger than those of other compounds. These apparently contradictory experimental results have been consistently rationalized through a electron transfer mechanism which is supported by DV- Xα molecular-orbital calculations. The strong Kβ ″ satellite signifies the formation of strong molecular orbitals through which the 3p −1 shake-off hole is delocalized, resulting in a weak multivacancy ( KM → LM ) Kα ″ satellite. (iv) The Kα ″ and Kβ ″ satellites for Sc metal was found to be strong, because the conduction electrons moves more freely to screen the core hole than the 3p −1 hole does. The Kβ ″ satellite has been assigned to the hole transition from 1s −1 to an antibonding molecular orbital which is formed between the center Sc 3 p and the neighboring Sc 3 p orbitals. (v) While the Kα 1 , chemical shift was found to be well correlated to the electronegativity of the neighboring atoms, the Kβ 1,3 shift has not been directly correlated to the effective charges on the Sc atom. The latter is due to a large orbital interaction between Sc 3 p and ligand atomic orbitals. It was concluded from the chemical shift of Kα 1 that the 3 d orbital population after the formation of chemical bond is decreased from that of the free Sc atom.

Analysis of surface composition and internal structure of fly ash particles using an ion and electron multibeam microanalyzer

Abstract An ion and electron multibeam microanalyzer was developed and applied to analysis of coal fly ash particles. Employing ordinary TOF-SIMS function, it was found that the surface of the fly ash particles mainly consisted of Ca, C, Si, and Na. A special analysis technique with a combination of “shave-off” cross-sectioning and TOF-SIMS mapping of the cross section was adopted to a single fly ash particle in order to reveal the internal structure. It was found that the particle had a cenosphere structure. TOF-SIMS mapping of the cross-sectioned particle clarified that the particle had the following layers, outermost layer (Na, Si, Ca-rich), shell (Na-rich), inner shell (Na, Si, Al-rich).