On the Limitation of Net Algorithm for Enumerating Isomeric Structures of Giant Fullerenes

Application of our net algorithm to the generation of all possible IPR isomers for giant fullerenes C_n, n=102 to 120, missed nine out of 39,621 possible structures. Analysis revealed that the omission of too small and too large cap triangles was the reason. Within the range of fullerenes studied, the missed structures are of high-energy and do not affect the distribution of significantly low-energy isomers.     

Doubly Bonded C60 Dimers and Congeners: Computational Studies of Structures, Bond Energies and Transformations

Initial steps of thermal transformation from doubly bonded [2+2] (1) and [4+4] (2) dimers of C₆₀ have been analyzed on the basis of computed structural features and Pople's energy partition scheme. Completely conjugated C₁₂₀ structures 3 and 4 are found to be considerably stable and proposed to be important intermediates. The linkage patterns in 3 and 4 are also likely to appear in the repeating units of the metastable dimer and polymer phases of A₁ crystals.     

Hot-carrier effects in scaled MOS devices

A universal guideline and state-of-the-art hot-carrier effects in scaled MOSFETs are reviewed and discussed from the viewpoints of 1) DC and AC hot-carrier effects, 2) hot-carrier detrapping phenomena, 3) mechanical stress effects on hot-carrier phenomena, and 4) hot-carrier resistant device structures.In the deep-submicron region, the hot-carrier applicable voltage is less than 3 V, so AC hot-carrier effects from the dynamic operation of actual circuits should be taken into account. Despite much experimentation and analysis, there is still no universally accepted theory that explain the AC degradation mechanism. This is because the noise caused by the wiring inductance in ULSI circuits and in measurement systems screens the intrinsic AC hot-carrier effects.Here, AC hot-carrier degradation enhanced by gate pulse-induced-noise is analyzed experimentally and theoretically. After eliminating the noise problem, it is found that AC hot-carrier degradation in LDD (Lightly doped drain) and GOLD (gate-drain overlapped device) structures can be estimated based on DC degradation in terms of the effective stress time which takes the duty ratio into account. In addition, it is found that the noise is negligible when the wiring inductance is smaller that 80 nH (250 mω), which is important for future circuit design.Furthermore, hot-carrier detrapping effects, especially in p-channel MOS devices, and hot-carrier phenomena under mechanical stress are investigated experimentally to better understand the underlying hot-carrier physics. Finally, future hot-carrier resistant device structures are discussed.     

Numerical analysis of wave-type heat transfer propagating in a thin foil irradiated by short-pulsed laser

This paper presents a numerical simulation of wave-type heat transfer phenomena propagating in an aluminum thin foil irradiated by a pulsed laser using the cubic interpolated propagation method coupled with a thermo-convective model. We did not use the two-step model and dual-phase lag model, which are generally known as the non-Fourier heat conduction law, but wave-type heat transfer phenomena could be observed by our method. The main characteristic of the method is to solve the governing equation including the equation of continuity, the equation of motion, the equation of energy and the equation of state. It is found that when the pulse duration is under the order of picosecond, the pure heat conduction is hardly observed and heat transfer toward the inside of materials occurs only by a thermal shock wave. The heat conduction mode after pulse laser irradiation is strongly dependent upon the value of total incident laser energy density E_in and the threshold value for pure heat conduction is 5.0 × 10⁴ J/m² for an aluminum.     

Catalytic decomposition of biomass tars with iron oxide catalysts

Catalytic gasification of wood (Cedar) biomass was carried out using a specially designed flow-type double beds micro reactor in a two step process: temperature programmed non-catalytic steam gasification of biomass was performed in the first (top) bed at 200–850 °C followed by catalytic decomposition gasification of volatile matters (including tars) in the second (bottom) bed at a constant temperature, mainly 600 °C. Iron oxide catalysts, which transformed to Fe₃O₄ after use possessed catalytic activity in biomass tar decomposition. Above 90% of the volatile matters was gasified by the use of iron oxide catalyst (prepared from FeCl₃ and NH_3aq) at SV of 4.5 × 10³ h^?1. Tar was decomposed over the iron oxide catalysts followed by water gas shift reaction. Surface area of the iron oxide seemed to be an important factor for the catalytic tar decomposition. The activity of the iron oxide catalysts for tar decomposition seemed stable with cyclic use but the activity of the catalysts for the water gas shift reaction decreased with repeated use.     

BaO—CaO—Na2O—CaF2—Cr2O3渣系的不锈钢脱磷

测定了１５００℃时磷在ＢａＯ－ＣａＯ－Ｎａ２Ｏ－ＣａＦ２－Ｃｒ２Ｏ３渣子和０．１２Ｃ－０．７１Ｓｉ－１８Ｃｒ不锈钢熔体之间的分配比，试验结果表明，该渣系的不锈钢脱磷能力比ＣａＯ基渣好，与ＢａＯ基渣相当。     

Thermal Transformation of Ring-Opened [2 2] C60 Dimer into a Wide-Bridged C120 Isomer. A Computational Evaluation of Fulvalene-Naphthalene Rearrangements

As a continuation of the studies on thermal transformation of the [2+2] C₆₀ dimer (1), the consequence of the pyracylene-rearrangement-like valence isomerization of the fulvalene partial structure at the bridge of the ring-opened product from 1, namely 2, was searched by dynamic reaction coordinate /AM1 semiempirical MO calculations. It is predicted that the fulvalene bridge of 2 rearranges into naphthalene partial structure by the concerted 'in-plane' mechanism to give a wide-bridged C₁₂₀ intermediate having twenty five-membered rings and two ten-membered rings (3). The computed energy of activation (145 kcal/mol) is 40 kcal/mol lower than those computed for pyracylene rearrangements. In contrast, the recently reported analogous rearrangement of indigo (13) to dibenzonaphthyridindione (14) is computed to occur by the stepwise 'sp³' mechanism.     

Series resonant ZCS‐PFM DC‐DC power converter with high‐frequency high‐voltage transformer link for high‐power magnetron drive

This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126     

Polyacene capacitors

We fabricated two types of polyacene capacitor with extremely stable polyacenic semiconductor (PAS) as the positive and negative electrodes. The first one is a coin-type PAS capacitor (six different sizes), which possesses large capacity with high reliability. Its capacity is much larger than that of the conventional electric double-layer capacitor which uses activated carbon as electrode. PAS capacitor can maintain more than 70% of the initial capacity even after 100 000 cycles. Moreover, this capacitor can be charged and discharged in a few minutes as well as at low rate. The second one is a cylinder-type PAS capacitor (diameter: 18 mm, height: 65 mm) which shows high capacity of 100 F and can discharge at the extremely high rate of 80 C. The coin-type PAS capacitor is currently used for memory back-up of electrical and communication equipment, and the cylinder-type is considered to be useful as power back-up for starting drive parts of electric equipment which needs high power density.