Hydrogen absorption enhancement of nanocrystalline Li3N/Li2C2 composite

A nanocrystalline composite of lithium nitride and lithium carbide was synthesized through melt infiltration of lithium metal into the mesopores of carbon aerogels followed by nitrogenation with nitrogen gas. The structure, surface properties, and morphology of the prepared samples were examined by XRD, N₂ adsorption at 77 K, FE-SEM, FE-TEM, and TPD/MS. It was found that some of the lithium metal reacted with the carbon to form lithium carbide, and some of the lithium metal was transformed into lithium nitride by nitrogenation, yielding a composite of lithium nitride and lithium carbide. Relative to the bulk lithium nitride, the lithium nitride in the composite showed a significantly enhanced sequential hydrogen absorption capacity and a lowered temperature of hydrogenation/dehydrogenation.     

Quantum Effects on Hydrogen Isotopes Adsorption in Nanopores

We have investigated the applicability of simulations and theoretical techniques for exploring the selectivities of hydrogen isotopes. We have simulated the adsorption isotherms of H₂ in an idealized carbon slit pore at 77 K by using the grand canonical Monte Carlo simulations with the Feynman-Hibbs effective potential (FH-GCMC) and the rigorous path integral method (PI-GCMC), and we obtained good agreement between the isotherms from both simulations. This suggests that FH-GCMC, which uses the approximative Feynman-Hibbs treatment, is as useful as PI-GCMC for exploring H₂ adsorption at 77 K. Moreover, we show that the ideal adsorption solution theory (IAST) can predict the selectivity of D₂ over H₂ in the interstices of single-wall carbon nanotube (SWNT) bundles at 77 K (below 0.1 MPa) very well by comparing the obtained results with the mixture adsorption FH-GCMC simulations. This indicates that IAST is also applicable to the estimation of the selectivity of D₂ over H₂ at moderate pressures and at 77 K from experimental single-component adsorption isotherms. We also demonstrate that the FH-GCMC simulation can reproduce the experimental adsorption isotherms of H₂ and D₂ in aluminophosphate AlPO₄-5 at 77 K. Finally, we analyze the selectivity of D₂ over H₂ by IAST with the experimental single-component adsorption isotherms of H₂ and D₂ at 77 K for a variety of adsorbents: AlPO₄-5, activated carbon fibers (ACFs), HiPco SWNT, and SWNHs. The selectivities predicted by the experimental adsorption data based on the results from the FH-GCMC simulations are presented and discussed.     

A passive EMI filter with access to the ungrounded motor neutral line—Its effect on attenuating bearing current

This paper describes the effect of a passive EMI filter on preventing bearing current from flowing inside an inverter‐driven motor. Motor‐bearing damage is often caused by bearing currents resulting from the breakdown of grease films in the motor bearing. The high‐frequency common‐mode voltage generated by the PWM inverter induces a shaft voltage between the rotor and the frame. When the shaft voltage exceeds the breakdown voltage of the grease films, a destructive instantaneous discharge current with a peak value of about 1 A flows through the motor bearing. The passive EMI filter, which is unique in access to the motor neutral line, can reduce the shaft voltage as a result of eliminating the high‐frequency common‐mode voltage from the motor terminals. Hence, no breakdown occurs in the grease film, so that no bearing current flows. The viability and effectiveness of the passive EMI filter is verified by experimental results obtained from a 400‐V, 3.7‐kW laboratory system. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 78– 87, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20489     

Track structure for low energy ions including charge exchange processes

The model and development is described of a new generation of Monte Carlo track structure codes. The code LEPHIST simulates full slowing down of low-energy proton history tracks in the range 1 keV-1 MeV and the code LEAHIST simulates low-energy alpha particle history tracks in the range 1 keV-8 MeV in water. All primary ion interactions are followed down to 1 keV and all electrons to 1 eV. Tracks of secondary electrons ejected by ions were traced using the electron code KURBUC. Microdosimetric parameters derived by analysis of generated tracks are presented.     

Elimination of artifacts in MRCP: technical consideration

Artifacts of MR cholangiopancreatography (MRCP) include fluid-filled gastrointestinal tracts, respiratory motion artifacts, spasm of Oddi's sphincter, vascular compression of bile ducts, overlapping of various anatomical structures and bright signal of surrounding fatty tissue. In this article, various technical considerations to eliminate these artifacts were described for the better imaging analysis of MRCP. The use of high-concentration ferric ammonium citrate (Ferriseltz) is recommended to reduce bright signal of fluid-filled gastrointestinal tracts. In case of long breathhold sequences, O2-inhalation study is useful to eliminate respiratory motion artifacts. Careful attention should be paid to the spasm of Oddi's sphincter and the vascular compression of bile ducts to avoid erroneous interpretation of MRCP findings.     

Gas analysis of the CVD process for high yield growth of carbon nanotubes over metal-supported catalysts

Changes in the gas composition during the methane chemical vapor deposition growth of single- and double-walled carbon nanotubes over metal-supported MgO catalysts were investigated in an attempt to increase the nanotube yield. Monitoring the gas composition by gas chromatography as a function of the reaction time provides information on the activity and lifetime of the catalyst. The degree of methane decomposition, i.e., the C-H bond dissociation, was closely related to the nanotube yield, and the Fe-Mo binary catalyst exhibited a high activity. The effects of water vapor on the catalytic nanotube growth were also studied by introducing water vapor in the inlet gas. An appropriate amount of water prolonged the lifetime of the catalyst and increased the nanotube yield by 35%.     

Electrospray Deposition of Photoresist: A Low Impact Method for the Fabrication of Multilayered Films

Electrospray deposition has been investigated as a substitute for photoresist spin coating. The morphology of Microposit S1813 photoresist films has been studied as a function of several spray conditions including resist concentration, substrate surface, and flow rate. Film morphology is controlled by three process parameters: the surface energy determines the equilibrium conditions of resist on the substrate; the viscosity and volume flux determine the relaxation time for the depositing resist solution after impact on the substrate. Electrosprayed photoresist films have been used for photolithographic patterning and it has been demonstrated that electrospray deposition is an effective method for deposition of photoresist on top of fragile, thin films, which can be used for multilayered thin film fabrication.

     

Development of silicon wafer packaging technology for deep UV LED

This paper reports a deep‐ultraviolet LED (deep‐UV‐LED) package based on silicon MEMS process technology (Si‐PKG). The package consists of a cavity formed by silicon crystalline anisotropic etching, through‐silicon vias (TSVs) filled with electroplated Cu, bonding metals made of electroplated Ni/AuSn and a quartz lid for hermetic sealing. A deep‐UV LED die is directly mounted in the Si‐PKG by AuSn eutectic bonding without a submount. It has advantages in terms of size, heat dissipation, light utilization efficiency, productivity and cost over conventional AlN ceramic packages. We confirmed a light output of 30 mW and effective reflection on Si (111) cavity slopes in the Si‐PKG. Based on simulation, further improvement of the optical output is expected by optimizing DUV‐LED die mount condition.     

Accurate and efficient RTL power estimation based on power contour model

This paper proposes a new RTL power estimation method based on a power contour model. The model achieves accurate and efficient power estimation. The experimental results show that the maximum error is reduced by 56.19% and the RMS error is also reduced by 3.41% compared to the conventional table‐based RTL power estimation. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(3): 48–56, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22340     

Preparation of SrBi 2 Ta 2 O 9 Thin Films by Liquid-Delivery MOCVD Without Additional Solvents

SrBi 2 Ta 2 O 9 thin films were prepared by ECR plasma enhanced metalorganic chemical vapor deposition (ECR-MOCVD) with a liquid-delivery system using one cocktail source without an additional solvent. The strontium-tantalum double alkoxide, Sr{Ta[OC 2 H 4 H(CH 3 ) 2 ](OC 2 H 5 ) 5 } 2 , was dissolved in stabilized trimethyl bismuth, Bi(CH 3 ) 3 / dioxane. This source system has been used in a conventional bubbling system. Deposition rate and the composition of the films were strictly controlled by the concentration and the composition of the cocktail source. Therefore, high reproducibility was realized by using this system. The constituent phase of the stoichiometric SBT film as-deposited at 500 C on a (111)Pt/TiO 2 /SiO 2 /Si substrate was a fluorite phase and transformed to the single phase of SBT by the post annealing at 800 C. It showed almost the same ferroelectricity as the stoichiometric composition film.