Nondestructive investigation of β-FeSi2/Si interface by photoluminescence measurements

Ion-beam-synthesized β-FeSi₂/Si interfaces were investigated by carrier-injection photoluminescence (CPL) measurements. The CPL intensity of Al-doped β-FeSi₂/Si sample was larger than that of non-doped one. We obtained a carrier injection efficiency (γ) of γ = 0.41 in the Al-doped sample and γ = 0.19 in the non-doped one. These results revealed that Al-doping into β-FeSi₂ is an effective technique for the improvement of β-FeSi₂/Si interface which is defective due to ion implantation damages.     

Degradation of Superconductivity in Annealed Irradiated Bi2Sr2CaCu2O8+δ Single Crystals During Exposure to Air

As for irradiated Bi₂Sr₂CaCu₂O₈₊ single crystals annealed in flowing N₂ atmosphere, flowing O₂ atmosphere, and air, their superconductivity was degraded during exposure to air. The degradation of superconducting transition temperature T _c is attributed to the doping of oxygen. The small recovery of T _c may be related to the redistribution of oxygen. The superconductivity of samples annealed in N₂ atmosphere and air is more stable than that of the sample annealed in O₂ atmosphere during exposure to air.     

Fabrication of translucent AlN ceramics with MgF2 additive by spark plasma sintering

Translucent AlN ceramics with 0‐2 wt.% MgF₂ additive were prepared by spark plasma sintering. AlN powder was heated temporarily up to 2000°C, before holding at 1850°C for 20 minutes in N₂ gas. The sintered ceramics consisted of a single phase of hexagonal AlN, and showed a transgranular fracture mode. The total transmittance was improved remarkably by the additive, to reach 74% at a wavelength of 800 nm for 1 wt.% MgF₂. For 2 wt.% MgF₂, the transmittance was slightly lower than that for 1 wt.% MgF₂, and an absorption band was observed apparently at around 400 nm. The addition of MgF₂ along with the temporary heating at higher temperatures than the sintering temperature contributed to improve the transmittance remarkably.     

Fluoroscopic bone fragment tracking for surgical navigation in femur fracture reduction by incorporating optical tracking of hip joint rotation center

A new method for fluoroscopic tracking of a proximal bone fragment in femoral fracture reduction is presented. The proposed method combines 2-D and 3-D image registration from single-view fluoroscopy with tracking of the head center position of the proximal femoral fragment to improve the accuracy of fluoroscopic registration without the need for repeated manual adjustment of the C-arm as required in stereo-view registrations. Kinematic knowledge of the hip joint, which has a positional correspondence with the femoral head center and the pelvis acetabular center, allows the position of the femoral fragment to be determined from pelvis tracking. The stability of the proposed method with respect to fluoroscopic image noise and the desired continuity of the fracture reduction operation is demonstrated, and the accuracy of tracking is shown to be superior to that achievable by single-view image registration, particularly in depth translation.     

Bioactivity of CaSiO<Subscript>3</Subscript>/poly-lactic acid (PLA) composites prepared by various surface loading methods of CaSiO<Subscript>3</Subscript> powder

Mixing bioactive ceramic powders with polymers is an effective method for generating bioactivity to the polymer-matrix composites but it is necessary to incorporate up to 40 vol% of bioactive ceramic powder. However, such a high mixing ratio offsets the advantages of the flexibility and formability of polymer matrix and it would be highly advantageous to lower the mixing ratio. Since surface loading of ceramic powders in the polymer is thought to be an effective way of reducing the mixing ratio of the ceramic powder while maintaining bioactive activity, CaSiO₃/poly-lactic acid (PLA) composites were prepared by three methods; (1) casting, (2) spin coating and (3) hot pressing. In methods (1) and (2), a suspension was prepared by dissolving PLA in chloroform and dispersing CaSiO₃ powder in it. The suspension was cast and dried to form a film in the case of method (1) while it was spin-coated on a PLA substrate in method (2). In method (3), CaSiO₃ powder was surface loaded on to a PLA substrate by hot-pressing. The bioactivity of these samples was investigated in vitro using simulated body fluid (SBF). Apatite formation was not observed in the samples prepared by method (1) but some apatite formation was achieved by mixing polyethylene glycol (PEG) with the PLA, producing a porous polymer matrix. In method (2), apatite was clearly observed after soaking for 7 days. Enhanced apatite formation was observed in method (3), the thickness of the resulting apatite layers becoming about 20 μm after soaking for 14 days. Since the amount of CaSiO₃ powder used in these samples was only ≤0.4 vol%, it is concluded that this preparation method is very effective in generating bioactivity in polymer-matrix composites by loading with only very small amounts of ceramic powder.     

Ion channeling study of epitaxy of iron based Heusler alloy films on Ge(111)

We have investigated perfection of atomic rows on iron-based Heusler alloy films on Ge(111) planes by using ion channeling technique in order to find the dominant factors for the perfection. Fe₃Si/Ge(111) and Fe₂CoSi/Ge(111) have a high quality of atomic rows at the heterointerface like that of perfect crystals. Fe_3−xMn_xSi/Ge(111) (x = 0.84, 0.72 and 0.36) interfaces have imperfection of atomic rows which may be controlled by both the lattice mismatch with the Ge substrate and the Mn-Si pairs due to the site disorder in the film with the Mn content x > 0.75. Analysis of axial channeling parameters employed in this study is very useful for quantitative evaluation of perfection of atomic rows at the heterointerface.     

Influence of activated carbon on crevice corrosion in adsorption tower of advanced liquid processing system

ABSTRACT

The adsorption tower made of type 316L stainless steel (SS) in Multi-nuclide Removal Equipment (Advanced Liquid Processing System) which uses Ag-impregnated activated carbon (Ag AC) as an adsorbent experienced crevice corrosion. The influence of Ag AC on the crevice corrosion susceptibility and E_sp of 316L SS was investigated by performing electrochemical experiments. Crevice corrosion was observed in the specimen in contact with the Ag AC. On the other hand, there was no crevice corrosion without the Ag AC in both pH 7.4 and pH 12 solutions. Clear ennoblement of spontaneous potential (E_sp) by in contact with activated carbon was observed and that was clearly higher than the repassivation potential for crevice corrosion (E_R,CREV). Thus, the presence of the AC notably increased E_sp of 316L SS and this resulted in increased crevice corrosion susceptibility by the galvanic effect.

This paper is part of a supplementary issue from the 17th Asia-Pacific Corrosion Control Conference (APCCC-17).     

Fates of foodborne pathogens in raw hams manufactured rapidly using a new patented method

To manufacture raw ham in an efficient manner, we recently developed a new system in which presliced pork loin was used, and the processing time was reduced to 5% of the conventional method. This study aimed to examine whether this raw ham could be as safe as ham produced by the conventional method. Pork loin spiked with enterohemorrhagic Escherichia coli serotype O157:H7, Listeria monocytogenes serotype 1/2c, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus were processed using either the new or conventional method. The fate of the foodborne pathogens and behavior of hygiene indicator bacteria were examined. Whereas nitrite had disappeared during the conventional packaging process, the reduced processing time in the new system allowed for the ham to be vacuum packed with retention of the nitrite (6.9±1.2 ppm, P<0.01). This accounts for the prominent decrease in L. monocytogenes (2.3 log reduction in 35 days) and S. aureus (3.3 log reduction in 13 days) counts during storage. E. coli O157 and Salmonella Enteritidis were likely resistant to the nitrite in the ham. However, they were unable to multiply in the ham and decreased gradually as in the conventionally produced ham. The bacteriostatic nature of the raw ham was also indicated by the gradual decrease in coliforms (1.3 log reduction in 13 days) in nonspiked ham. In conclusion, the raw ham produced using presliced pork loin is practically as safe as conventionally produced raw ham. It is worth validating these results in a small-scale production setting.     

Single-walled carbon nanotube growth with non-iron-group “catalysts” by chemical vapor deposition

Various materials have been found to “catalyze” carbon nanotube growth in chemical vapor deposition (CVD) when they become nano-sized particles. These involve not only metals, such as Pd, Pt, Au, Ag, and Cu, but also semiconductors, such as Si, Ge, and SiC. Alumina and diamond nanoparticles also produce carbon nanotubes. These “catalysts”, which are better called “seeds”, can be categorized into two types: one type forms a eutectic liquid or highly-mobile alloy with carbon, and carbon atoms precipitate from the eutectic alloy; the other type remains as a solid phase and form a carbon surface layer during CVD growth. In this paper, we review recent studies of SWCNT growth with these non-iron-group materials and highlight the mechanisms involved.