Synthesis of novel hydride Li3AlFeH8 at high temperature and pressure

Iron-containing complex hydrides are a fascinating class of materials for hydrogen storage applications because they consist of abundant iron and usually contains [FeH₆]^4? complexes, resulting in high hydrogen densities. In this study, we synthesized theoretically predicted Li₃AlFeH₈, which has the highest gravimetric hydrogen density of all transition metal complex hydrides, through a hydrogenation reaction of LiH, AlH₃, and pure iron powder mixture under high pressure. The reaction process was observed in situ using a synchrotron radiation x-ray diffraction technique to clarify its reaction kinetics. The reaction temperature and pressure were changed to optimize reaction conditions for obtaining single phase Li₃AlFeH₈. Unfortunately, we did not obtain single phase Li₃AlFeH₈ because the reaction was slow. In addition, there were other phases with similar thermodynamic stabilities to that of Li₃AlFeH₈. Another novel hydride, LiAlFeH₆, was found to be synthesized above 850 °C at 9 GPa.     

Design of front-end circuit for Superconductive A/D converter and demonstration of operation up to 43 GHz

We designed a front-end circuit for an analog-to-digital (A/D) converter based on single flux quantum circuitry and tested its functionality at a frequency of up to 43 GHz. The front-end circuit consisted of a pulse generator, a sigma-delta modulator, a 1-to-8 demultiplexer (DEMUX), and superconducting quantum interference device (SQUID) amplifiers. There were 2518 Josephson junctions in the front-end circuit. To operate the circuit at high speed, we designed robust timing against variations in circuit parameters. By using circuit simulations based on the Monte Carlo method, we estimated spread in time lag between clock and data pulses. From this estimate, the timing was optimized to operate the circuit at 40 GHz. The demonstration of the front-end circuit was carried out using the on-chip testing method. Output data were acquired from the modulator through DEMUX. We confirmed proper sigma-delta modulation by analyzing the dependence of the density "1" in the output data on input current level. The proper operation was confirmed in a range of 37-43 GHz. Furthermore, the amplification by the SQUID amplifier was also confirmed at low speed. These results indicate the complete operation of the front-end circuit for superconductive A/D converter.     

Linear voltage-to-current converters with current reuse technique

This paper proposes a linear voltage-to-cur-rent converter with current reuse technique to reduce circuit power consumption without deteriorating its linearity and bandwidth. The proposed circuit is designed using 0.18???m CMOS process parameters from TSMC. Simulation results show that the total harmonic distortion (THD) of the proposed circuit with a 2.5-V input amplitude is less than 1% for input frequency up to 200?MHz under a 1.8-V supply voltage. The total current consumption is 10.8?mA.     

dBm average optical output power operation of small-chirp 40-gbps electroabsorption Modulator with tensile-strained asymmetric quantum-well absorption Layer

A small-chirp 40-Gbps electroabsorption modulator (EAM) with high optical output power capability has been developed for the first time. An optimized tensile-strained asymmetric quantum-well structure is employed as the absorption layer of the EAM so that small chirp and reduction of the lifetime of the photogenerated holes for high optical output power tolerance is obtained. Deteriorations of frequency response and chirp due to carrier pileup under high optical output power conditions were prevented by enhancing carrier sweepout, which was experimentally confirmed as a hole lifetime as short as 35 ps under high optical output power conditions. As a result, good frequency response (bandwidth > 30 GHz) and small chirp (/spl alpha/<1) were obtained under the condition of the zero bias voltage and +4.5 dBm continuous-wave (CW) optical output power (P/sub out,CW/). Clear eye opening and high dynamic extinction ratio under 40-Gbps non-return-to-zero modulation persisted to a high average output power (P/sub out,ave/) condition of P/sub out,ave/=+1.0 dBm.     

Design of a 300 GHz Band TWT with a Folded Waveguide Fabricated by Microelectromechanical Systems

For future broadband wireless links, we have designed a 300 GHz band traveling wave tube (TWT) with a folded waveguide fabricated by microelectromechanical systems (MEMS). The TWT operates at a beam voltage of 12 kV and a beam current of 8.3 mA. The classical large signal simulation code predicts the output power greater than 1 W and gain larger than 20 dB over the bandwidth from 280 to 300 GHz.     

Characteristics of metal-insulator-metal diodes as generators offar-infrared radiation

Characteristics of metal-insulator-metal (MIM) diodes which are used as mixer-generators of far-infrared (FIR) radiation have been investigated for nine different diode base metals. It was found that a W-Fe diode works as effectively as a W-Co diode in generating tunable FIR radiation by mixing two CO₂ lasers and microwave radiation. The bias dependences of W-Ni, W-Co, and W-Fe MIM diodes have also been examined. Observed bias results can be predicted by analyzing their current-voltage characteristics     

Immunocytochemical studies on co-localization of alpha-granule membrane alphaIIbbeta3 integrin and intragranular fibrinogen of human platelets and their cell-surface expression during the thrombin-induced release reaction

We employed a double-staining method to immunocytochemically study the role of alpha-granule membrane alphaIIbbeta3 integrin in the expression of intragranular fibrinogen (Fbg) and albumin on the surface of thrombin-activated human platelets. In unstimulated platelets, alphaIIbbeta3 was distributed along the alpha-granule membrane as well as on the cell-surface membrane, including the open canalicular system (OCS), while Fbg and albumin were exclusively and evenly detected in the granules. At 30 s after activation by 0.1 U ml(-1) thrombin under non-stirred conditions, a small amount of Fbg in the granules was redistributed in association with alpha-granule membrane alphaIIbbeta3, suggesting that co-localization between alphaIIbbeta3and Fbg occurs at this period during platelet activation. At 1-5 min, the shape of the platelets changed from discoid to spheroid with pseudopodia and intact alpha-granules were no longer observed in these cells. Fibrinogen associated with alphaIIbbeta3 became increasingly expressed on the membranes of both the swollen OCS and the cell surface. Nevertheless, abundant Fbg still remained in the lumen of the swollen OCS, the membrane of which had already been depleted of alphaIIbbeta3. By western blot analysis using anti-human Fbg antibody, we detected no Fbg in the surrounding medium of the thrombin-stimulated platelets for 5 min. Unlike Fbg, abundant albumin in the alpha-granules was released into the surrounding medium without association with the membrane of either the alpha-granules or the cell surface. These results suggest that a small portion of the intragranular Fbg may bind to an Fbg binding site expressed on the activated aIIbbeta3 on the alpha-granule membrane, resulting in the formation of an alphaIIbbeta3-Fbg complex, which is then moved through the OCS membrane and expressed on the cell-surface membrane. Thus, alpha-granule membrane aIIbbeta3 may act as a carrier of intragranular Fbg.     

Enantiomer separations of mixtures of monoacylglycerol derivatives by HPLC on a chiral column

High-performance liquid chromatographic separations of monoacylglycerol enantiomeric mixtures as their di-3,5-dinitrophenylurethane derivatives were carried out on a chiral stationary phase, N-(R)-1-(α-naphthyl)ethylaminocarbonyl-(S)-valine bonded to silica gel. The conditions for the quantitative analysis ofsn-1 andsn-3 enantiomeric mixtures of six saturated 1-monoacylglycerols having consecutive even carbon numbers and ofsn-1 andsn-3 enantiomeric mixtures of 1-stearoyl-, 1-oleoyl-, 1-linoleoyl-, and 1-linolenoyl-glycerols were obtained. The linear relationships of logarithmic retention volumes against the number of carbons and olefinic bonds for the enantiomer homologous series are discussed, and a new concept of enantiomer separation is presented.     

Immunocytochemical localization of amelogenin in rat incisor ameloblasts using ultrathin frozen sections

The localization of amelogenin, an enamel matrix protein, was examined by ultrastructural immunocytochemistry using unembedded ultrathin frozen sections of undecalcified rat incisor ameloblasts. Antibody against bovine amelogenin labeled Golgi complexes, secretory granules, and lysosomal structures in the preameloblasts and inner enamel-secretory ameloblasts as well as the enamel. The antibody also labeled dentin matrix facing preameloblasts. These results support the findings in previous reports using conventional epon embedded specimens. However, rough-surfaced endoplasmic reticulum failed to be labeled by this antibody.