Evidence for Ongoing Modeling-Based Bone Formation in Human Femoral Head Trabeculae via Forming Minimodeling Structures: A Study in Patients with Fractures and Arthritis.

Bone modeling is a biological process of bone formation that adapts bone size and shape to mechanical loads, especially during childhood and adolescence. Bone modeling in cortical bone can be easily detected using sequential radiographic images, while its assessment in trabecular bone is challenging. Here, we performed histomorphometric analysis in 21 bone specimens from biopsies collected during hip arthroplasty, and we proposed the criteria for histologically identifying an active modeling-based bone formation, which we call a "forming minimodeling structure" (FMiS). Evidence of FMiSs was found in 9 of 20 specimens (45%). In histomorphometric analysis, bone volume was significant higher in specimens displaying FMiSs compared with the specimens without these structures (BV/TV, 31.7 ± 10.2 vs. 23.1 ± 3.9%; p < 0.05). Osteoid parameters were raised in FMiS-containing bone specimens (OV/BV, 2.1 ± 1.6 vs. 0.6 ± 0.3%; p < 0.001, OS/BS, 23.6 ± 15.5 vs. 7.6 ± 4.2%; p < 0.001, and O.Th, 7.4 µm ± 2.0 vs. 5.2 ± 1.0; p < 0.05). Our results showed that the modeling-based bone formation on trabecular bone surfaces occurs even during adulthood. As FMiSs can represent histological evidence of modeling-based bone formation, understanding of this physiology in relation to bone homeostasis is crucial

Effects of synthesis conditions on the structural features and methane adsorption properties of single-walled carbon nanohorns prepared by a gas-injected arc-in-water method

Single-walled carbon nanohorns (SWCNHs) can be easily synthesized via a gas-injected arc-in-water method that is considered to be a cost-effective technique. The electrode configuration and duration of arc discharge were modified in order to enhance the yield and methane-adsorption properties of SWCNHs. As a result, the yield of the SWCNHs was significantly increased by increasing the discharge time and the size of the cathode. Using these modified conditions, the horn units in the SWCNH aggregates increased in size, and the thermal stability of SWCNHs in an oxidative environment increased accordingly. Ab initio molecular orbital calculations were used to explain the trend in the thermal stability. When the conventional conditions were applied, a burn-off of about 40% was necessary in order to achieve the maximum specific surface area and micropore volume. Remarkably, by enlarging the cathode size, the burn-off can be reduced by almost half to achieve the enhanced micropore volume. As a result, SWCNHs obtained using the modified conditions adsorbed a larger amount of methane than did SWCNHs obtained from the conventional synthetic conditions. The effect of a mild oxidation treatment on SWCNHs on their methane adsorption suggested that SWCNHs with micropores would be more flexible than pristine SWCNHs. This tendency was elucidated using a molecular mechanics calculation

Cr as a key factor for direct synthesis of multi-walled carbon nanotubes on industrial alloys

Six kinds of industrial alloys, SUS316, FCH2, Invar, Permalloy, Inconel, and Nichrome, and three kinds of pure metals, Fe, Ni, and Cr, were used for substrates on which multi-walled carbon nanotubes (MWCNTs) were directly synthesized from ethylene. To activate their surfaces for the MWCNT formation, their surfaces were modified by two steps, (1) oxidation step in Ar–O2 mixture gas and (1) following reduction step in Ar–H2 mixture gas. It was discovered that Cr is a key component to realize the catalytic growth of MWCNTs on Fe and Ni emerged from the alloys. Using SUS316 to observe the influence of oxidation duration on MWCNT diameter, it was seen that increasing the oxidation duration resulted in the increase of the MWCNT diameter. This tendency can be explained by diffusion of Fe through Cr-rich layer, which causes the increase of catalyst particle diameters. The excess Fe diffusion through the Cr-rich layer resulted in the formation of a unique mushroom structure. These effects seen in the observation on the oxidation duration did not appear when reduction duration was prolonged because the Cr-rich layer could inhibit the Fe diffusion. Instead, the length of the MWCNTs can became maximum by employing an appropriate reduction duration

Synthesis of single and multi unit-wall MgB[sub 2] nanotubes by arc plasma in inert liquid via self-curling mechanism

Magnesium diboride (MgB2) is known as a promising superconductor due to its high transmission temperature. Similarly to single-wall carbon nanotube, unique characteristics would be seen if a nanotube structure of MgB2 having a unit-wall of Mg and B atomic bilayer is prepared. However, such MgB2 nanotubes have not ever been synthesized. In this article, formation mechanism of unit-wall MgB2 nanotube is elucidated by molecular mechanics calculation. From the viewpoint of energetic stability, the unit-wall will be curled up to form nanotube structure when MgB2 crystal is disassembled to an isolated unit-wall layer. An experiment using arc plasma in inert liquid was utilized to produce unit-wall MgB2 nanotubes. As a result, a single and multiunit-wall MgB2 nanotube was successfully synthesized. In this reaction field, the arc plasma may play a role to produce isolated MgB2 unit-wall fragment, and the cold cathode surface can contribute to preserve MgB2 nanotube structure

選択的電子付着を利用した気体精製技術の開発

京都大学0048新制・課程博士博士(工学)甲第6851号工博第1602号新制||工||1066(附属図書館)15938UT51-97-H235京都大学大学院工学研究科化学工学専攻(主査)教授 岡﨑 守男, 教授 橋本 健治, 教授 増田 弘昭学位規則第4条第1項該当Doctor of EngineeringKyoto UniversityDA