Finite element analysis of the magnetomechanical behavior of a toroidal coil with magnetic mirrors

A toroidal simulator is used to study the magnetomechanical behavior of a superconducting D-shaped coil set at the center between sectored ferromagnetic plates. Since the magnetic field distribution between the two plates is expected to be almost the same as that created by toroidal field coils arrayed in a torus, the toroidal simulator may be expected to show almost the same magnetomechanical behavior as that of the full torus coils. To verify its validity experimentally, buckling and vibration tests were carried out in a liquid helium cryostat. In addition numerical analyses were performed for the magnetic field distribution to reveal its similarity and for the experimental results from the toroidal simulator to confirm its validity. Its validity is fully demonstrated in the present study.     

Fusion and molecular aspects of liposomal nanocarriers incorporated with isoprenoids

The present study was conducted to investigate whether typical isoprenyl compounds (TICs) can control liposomal fusion reactions through changes in the physical properties of membranes. The fusion capabilities of TIC-incorporated liposomes were characterized by measuring the 13C spin-lattice relaxation times (13CT1) and the gel permeation chromatogram (GPC) patterns. The 13CT1 relaxivities of some of these TIC-liposomes were remarkably enhanced at 27 degrees C. The highest 13CT1 value obtained was for the beta-carotene-liposome, which ruptured, and was attributed to the highest membrane fusion reactivity. The other TIC-liposomes incorporated with alpha-tocopherol, canthaxanthin, or coenzyme Q10 also induced significant fusion and did not rupture in comparison with the beta-carotene-liposome. These results show that the incorporations of TICs into lipid bilayers are useful to control liposomal nanocarriers for suitable membrane packing and advantageous phase separation, which could affect membrane-related processes.     

Evaluation of both image resolution and contrast-to-noise ratio in scanning electron microscopy

The contrast-to-gradient (CG) resolution has been defined as a weighted harmonic mean of the local resolution, i.e. the length defining the object's local fine structure at each pixel position. The newly defined resolution Res is defined as 2 sigma/ sqrt 2, where 2 sigma is a sharpness factor of the image pattern obtained by the conversion 2 sigma = ARCG + B using default constants A and B. In the present study, we have extended the algorithm to change the constants from default values to calibrated ones using standard images that are same in both pattern and contrast-to-noise ratio (CNR) as the original SEM image to be evaluated. The calibrated image resolution with a weak noise dependency is evaluated with the CNR as a given parameter.     

Simulation study on image contrast and spatial resolution in helium ion microscope

We performed Monte Carlo simulation of helium (He) ion induced secondary electron (SE) emission in order to compare the secondary electron image characteristics between He and gallium (Ga) scanning ion microscopes (SIM) and scanning electron microscope (SEM). For 10-50 keV He ion bombardment SE yield increases gradually with increasing the atomic number, Z2, of the target, as well as for the electron bombardment. However, for 30 keV Ga ion bombardment, SE yield shows an opposite Z2 dependence. The calculated SE yield is much larger than that for both electron and Ga ion bombardment. The incident angle dependence of the SE yield approximately obeys the inverse cosine law even at high angles of 85 degrees and more. On the other hand, for electron bombardment, the incident angle dependences are much weaker for low energy and high Z2. These indicate that the image contrast on He-SIM is clearer than those of SEM. Among the electron excitations by incident He ions, recoiled target atoms and excited electrons, the first one having narrow excitation volume dominates the SE yield, so that the spatial image resolution in SIM using zero-diameter He beams with the energies of 10-50 keV is prospected to be smaller or better (<0.1 nm) than for 30 keV Ga ion and 1 keV electron beams.     

Thermal degradation characteristics of oil‐filled cable joint with extremely degraded tan δ oil

Much of oil‐filled (OF) cable has been used for a long time as 66‐ to 500‐kV extrahigh‐voltage cable. Sometimes we can see extremely degraded tan δ oil (several tens of percent of tan δ, for example) in joint boxes, etc. The values of tan δ calculated by a simple combination model of paper/oil show that the oil‐impregnated paper with such a high tan δ oil likewise has an extremely high tan δ, which must result in thermal breakdown. However, such an event has not taken place up to the present in actually operated transmission lines. This fact suggests that some mechanism for the suppression of tan δ has acted in the paper insulation impregnated with degraded tan δ oil. Therefore, we investigated in detail the tan δ characteristics of paper impregnated with extremely high tan δ oil. In addition, based on the investigation results, we developed a method for simulation of heat generation by dielectric loss in an OF cable joint (which has degraded tan δ oil). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(1): 1–10, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21184     

Hydrodechlorination of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) over supported ruthenium and other noble metal catalysts

The hydrodechlorination of CCl₂F–CClF₂ (CFC-113) was studied using silica- and activated carbon-supported Ru, Rh, Pd, and Pt catalysts. The activity of the catalysts changed with time-on-stream. Ru was most stable among the four noble metals and gave a simple product distribution yielding CClF=CF₂ (CFC-1113) and CHClF–CClF₂ (HCFC-123a) as main products. Over silica-supported Ru, CFC-1113 yield decreased gradually with time-on-stream but HCFC-123a yield did not change throughout the reaction, suggesting that these products were formed on different sites of Ru. XRD studies and temperature-programmed reduction of the spent catalyst revealed that the deactivation was caused by halogen-containing carbonaceous species accumulated on the Ru surface during the reaction. The carbonaceous species seemed to be formed on the active site for CFC-1113 formation. Because CFC-1113 selectivity was higher over the catalyst having higher Ru dispersion, it was assumed that the hydrodechlorination of CFC-113 is structure-sensitive and CFC-1113 formation is promoted by Ru having highly unsaturated coordination sphere.     

An enzyme catalyzing O-prenylation of the glucose moiety of fusicoccin A, a diterpene glucoside produced by the fungus Phomopsis amygdali

Isoprenoids form the largest family of compounds found in nature. Isoprenoids are often attached to other moieties such as aromatic compounds, indoles/tryptophan, and flavonoids. These reactions are catalyzed by three phylogenetically distinct prenyltransferases: soluble aromatic prenyltransferases identified mainly in actinobacteria, soluble indole prenyltransferases mostly in fungi, and membrane‐bound prenyltransferases in various organisms. Fusicoccin A (FC A) is a diterpene glycoside produced by the plant‐pathogenic fungus Phomopsis amygdali and has a unique O‐prenylated glucose moiety. In this study, we identified for the first time, from a genome database of P. amygdali, a gene (papt) encoding a prenyltransferase that reversibly transfers dimethylallyl diphosphate (DMAPP) to the 6′‐hydroxy group of the glucose moiety of FC A to yield an O‐prenylated sugar. An in vitro assay with a recombinant enzyme was also developed. Detailed analyses with recombinant PAPT showed that the enzyme is likely to be a monomer and requires no divalent cations. The optimum pH and temperature were 8.0 and 50 °C, respectively. K_m values were calculated as 0.49±0.037 μM for FC P (a plausible intermediate of FC A biosynthesis) and 8.3±0.63 μM for DMAPP, with a k_cat of 55.3±3.3×10^?3 s. The enzyme did not act on representative substrates of the above‐mentioned three types of prenyltransferase, but showed a weak transfer activity of geranyl diphosphate to FC P.     

Improvement of Electrical Contact Between TE Material and Ni Electrode Interfaces by Application of a Buffer Layer

A single ??-structure thermoelectric (TE) module based on p-type NaCo₂O₄, n-type Mg₂Si, and Ni electrode was fabricated by the spark plasma sintering (SPS) method. The NaCo₂O₄ powder was synthesized by using a metal?Ccitric acid complex decomposition method. Bulk Mg₂Si prepared by melt quenching was ground into a powder and sieved to particle size of 75???m or less. To obtain a sintered body of NaCo₂O₄ or Mg₂Si, the powder was sintered using SPS. Pressed Ni powder or mixed powder consisting of Ni and SrRuO₃ powder was inserted between these materials and the Ni electrode in order to connect them, and electrical power was passed through the electrodes from the SPS equipment. The open-circuit voltage (V _OC) values of a single module in which TE materials were connected to the Ni electrodes by using pressed Ni powder was 82.7?mV, and the maximum output current (I _max) and maximum output power (P _max) were 212.4?mA and 6.65?mW at ??T?=?470?K, respectively. On the other hand, V _OC of a single module in which TE materials and an Ni electrode were connected with a mixed powder (Ni:SrRuO₃?=?6:4 volume fraction) was 109?mV, and I _max and P _max were 4034?mA and 109?mW at ??T?=?500?K, respectively. These results indicate that the resistance at the interface between the TE materials and the Ni electrode can be decreased and the output power can be increased by application of a buffer layer consisting of Ni and SrRuO₃.     

Development of Molecular Sieves‐Supported Palladium Catalyst and Chemoselective Hydrogenation of Unsaturated Bonds in the Presence of Nitro Groups

The chemoselective hydrogenation of unsaturated bonds and azide functionalities is achieved in the presence of nitro groups by a heterogeneous palladium catalyst supported on molecular sieves (MS3A). The present method shows a wide‐range of applicability with regard to substrates and the catalyst can be easily prepared and reused at least three times without any loss of activity.