The top-bottom effect of a tilted thick specimen and its influence on electron tomography

We present the top-bottom effect (TBE) of a 5 microm thick amorphous specimen in a 3 MV ultrahigh voltage electron microscope (ultra-HVEM) and its influence on the quality of electron tomography (ET). The 40-nm gold particles on the top surface of the specimen tilted at different angles have been observed to be of poorer image quality than those on the symmetrical bottom surface obtained by tilting and turning over the specimen. The point spread function of the gold-particle images was calculated using the increment Wiener filter and the image-quality variation was then evaluated. The TBE is shown to become more remarkable with the increase of the effective thickness of the tilted specimen or the decrease of the magnification of the ultra-HVEM. The ET simulation indicates that the TBE may generate approximately 4% distortion in the radial direction of a reconstructed sphere model.     

Magnetoplumbite-Corundum Phase Equilibria in the System Sr─Fe─Al─O at 1100°C

The phase relations in the region of the Fe₂O₃- and Al₂O₃-rich sides of the quaternary system SrO─Fe₂O₃–Al₂O₃–B₂O₃ and the location of conjugation lines between magnetoplumbite solid solution SrO·(6 − x)Fe₂O₃·xAl₂O₃ and corundum (α-Fe₂O₃, α-Al₂O₃) phases were determined at 1100°C in air by using the flux-growth method based on the Ostwald ripening mechanism. Activity–composition relations and the lattice parameters along the magnetoplumbite solid solutions were also obtained.     

Optical and electrical properties of boron nitride oxide films

Polycrystalline boron nitride oxide (BNO) films are synthesized by RF magnetron sputtering. It is found that the bandgap of the BNO film increases with increasing oxygen composition. The bandgap energy as wide as 5.5 eV is obtained with oxygen composition of 17%. The electrical resistivity is estimated to be as high as 10¹³ Ωcm. Metal/BNO/metal structures are fabricated with various metals such as Ni, Cu and Al, and electrical characterization are performed for metal/BNO contacts. The true Schottky barrier heights are estimated for metal/BNO contacts. The true Schottky barrier height decreases with increasing metal work function. This behavior of the Schottky barrier height suggests that the BNO film has p-type electrical conduction.     

Dynamic change of copper in fly ash during de novo synthesis of dioxins

Although many researchers have reported that copper chloride is an important catalyst that generates relatively large amounts of dioxins in heat experiments involving model fly ash, details on the behavior of copper during the process are still unavailable. In this study, we used in situ XANES experiments involving one type of real fly ash, which originated from a municipal solid-waste incinerator (MSWI), and two fly ash models to investigate the behavior of copper in fly ash at temperatures that are suitable for de novo synthesis, which is the major formation route for dioxins during waste incineration and thermal processes. Cupric compounds in real fly ash and model fly ash A(CuCl2.2H2O + activated carbon (AC) + boron nitride (BN)) were reduced to cuprous compounds or elemental copper at low temperatures. The changes in the Cu XANES spectra of real fly ash were similar to those of model fly ash A and those of an oxychlorination catalyst. In model fly ash B (CuO + AC + KCl + BN), CuO did not vary dramatically in the temperature range studied. In this study, we found strong evidence that oxychlorination, the key mechanistic step in the formation of dioxins, occurred in both real MSWI and model fly ash.     

Dry etching properties of methyl-BCN film with C4F8 gas for Cu/low-k interconnection

Methyl-BCN is an attractive low-k material for the fabrication of next generation LSI device system. This paper describes dry etching of methyl-BCN film in order to develop interconnections for future devices. The methyl-BCN films were deposited by plasma-assisted chemical-vapor deposition (PACVD) using tris(dimethylamino)boron (TMAB) gas at 350 °C. We have investigated dry etching properties and mechanism of the methyl-BCN film using C₄F₈ gas with induced coupling plasma (ICP) etching equipment. In this study we used C₄F₈ gas whose atmospheric lifetime is less than one-sixteenth of the conventional CF₄ gas for suppression greenhouse gases. It was found that methyl bonds in the methyl-BCN film can be kept after dry etching, because the peak of C–H (2962 cm^?1) in Fourier transform infrared absorption (FTIR) spectra didn't significantly change after dry etching. X-ray photoelectron spectroscopy (XPS) analysis shows the presence of C–F₂ and C–F₃ bonds just on the methyl-BCN surface after dry etching and no traces of these bonds inside the film. It is observed that intensities of B–N and B–C bonds decrease after dry etching. This suggests that the etching of methyl-BCN films by C₄F₈ gas mainly involves boron desorption.     

A proteasome inhibitor lessens the increased aortic endothelin-1 content in deoxycorticosterone acetate-salt hypertensive rats

Deoxycorticosterone acetate (DOCA)-salt-treated rats developed marked hypertension after 4 weeks with an increase in aortic endothelin-1. Treatment of DOCA-salt hypertensive rats with a proteasome inhibitor, N-benzyloxycarbonyl-Ile-Glu(O-t-Bu)-Ala-leucinal, significantly reduced the elevation in systolic blood pressure and the effect was accompanied by a decrease in aortic endothelin- content. Thus, a proteasome-dependent proteolytic pathway appears to play an important role in the enhanced production of endothelin-1 in blood vessels and the consequent increase in blood pressure in this model of hypertension.     

Polyethylene wear from femoral bipolar neck-cup impingement as a cause of femoral prosthetic loosening

A 33-year-old woman underwent an uncemented bipolar hip arthroplasty for osteoarthrosis of the left hip in 1985. Because of painful aseptic loosening, the bipolar implant was revised to a total hip prosthesis in 1994. Membranous tissues around the implant histologically presented foreign-body reaction against polyethylene debris. The retrieved implant showed polyethylene wear of the rim of the bipolar cup. Three-dimensional measurement of the surface configuration of the polyethylene of the cup indicated that wear debris had been generated almost exclusively from femoral bipolar neck-cup impingement. Volumetric wear in the articulating dome portion of the polyethylene was negligible. This report clearly illustrates how impingement of a bipolar cup on the femoral neck can be a major source of polyethylene wear debris which induces femoral osteolysis and subsequent stem loosening.