Temperature control for the expansion of artificial DNA motif

The DNA, which forms a double helical conformation by the highly selective base-pairing rule with the width of 2 nm, is one of the polymers utilized as a template for nanoparticle assembly. Then, holiday junction structure, where two different DNA double strands intersect and replace each complement strand, is an important artificial motif for forming two-dimensional mesh-like DNA morphology. In this study, the two-dimensional sheet with the mesh-like conformation is formed and the growth of the DNA morphology is controlled by changing the temperature in the formation process. The influence of the cooling procedure on the formation process of the two-dimensional DNA sheet is observed by atomic force microscope, and the formation of double strands in the process is traced by absorption spectra. The spectroscopic results demonstrate that the two-dimensional DNA sheet is strongly dependent on the correlation between the applied cooling process and the melting temperature of double helical conformation, and that the growth of the two-dimensional DNA sheet can be manipulated by the cooling procedure. Further, we will show the size control of the DNA sheet by mixing the designed DNA which inhibits the growth of the DNA sheet.     

Feature extraction by supervised independent component analysis based on category information

Independent component analysis (ICA) is a technique of transforming observation signals into their unknown independent components; hence, ICA has often been applied to blind signal separation problems. In this application, it is expected that the obtained independent components extract essential information of independent signal sources from input data in an unsupervised fashion. Based on such characteristics, ICA is currently utilized as a feature extraction method for images and sounds for recognition purposes. However, since ICA is an unsupervised learning, the obtained independent components are not always useful in recognition. To overcome this problem, we propose a supervised approach to ICA using category information. The proposed method is implemented in a conventional three‐layered neural network, but its objective function to be minimized is defined not only for the output layer but also for the hidden layer. The objective function consists of the following two terms: one evaluates the kurtosis of hidden unit outputs and the other evaluates the error between output signals and their teacher signals. The experiments are performed using several standard datasets to evaluate performance of the proposed algorithm. It is confirmed that a higher recognition accuracy is attained by the proposed method as compared with a conventional ICA algorithm. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 25–32, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20522     

Evaluation of additive effects and homogeneity of the starting mixture on the nuclei-growth processes of barium titanate via a solid state route

In an attempt to obtain finest possible microparticles of BaTiO₃ (BT) with highest possible tetragonality via a solid state route, starting mixtures comprising BaCO₃ and TiO₂ were subjected to various pretreatments including addition of glycine and mechanical activation. Reaction processes were monitored by the changes in the weight, crystallinity, and morphology in detail. While mechanical activation with glycine significantly increased the rate of reaction and homogeneity of the particle size of the product, BT, simultaneous particle growth of BT was intolerably acute for micro-electronic devices. The fast particle coarsening was predominated by the coalescence of BT tiny particles formed around titania. A mixture with higher homogeneity was attained by using finer starting materials under wet mixing, avoiding significant mechanical stressing. Particle growth of BT was suppressed to ca. 100 nm to obtain fully crystallized BT particles without significant loss of tetragonality and, hence, close to meet our requirements for MLCCs.     

Nonstationary electron/hole transport in sub-0.1 μm MOS devices:correlation with mobility and low-power CMOS application

We have experimentally studied the high-lateral-field carrier velocity near the source edge in sub-0.1 μm MOSFETs. It is demonstrated that the high-field electron velocity and hole velocity have universal low-field mobility dependence. This shows that the hole velocity is lower than the electron velocity due to the hole's lower mobility. Moreover, we have investigated the low-power CMOS operation using the velocity overshoot. It is verified that there is a most suitable supply voltage for improving the CMOS operation using velocity overshoot. The most suitable supply voltage is shown to be about 1 V. Therefore, the velocity overshoot will be very useful for low voltage CMOS operation in the future     

Verification of the energy-saving effect of the district heating and cooling system—Simulation of an electric-driven heat pump system

A district heating and cooling system (DHC) is expected to be a promising energy-saving measure for high-density business areas in Japan. However, it has not been verified what advantages of the DHC are important for energy conservation. The clarification of this issue is supposed to contribute to improving the energy efficiency of the DHC.     

High-speed and low-driving-Voltage thin-sheet X-cut LiNbO/sub 3/ Modulator with laminated low-dielectric-constant adhesive

We present a novel thin-sheet X-cut LiNbO/sub 3/ optical modulator structure which can be fabricated by precise polishing and lapping to obtain a thinner LiNbO/sub 3/ substrate for a lower driving voltage in addition to velocity matching and impedance matching. We demonstrated that the fabricated modulator had a driving voltage V/spl pi/ of 2 V and zero chirp for 40-Gb/s operation and had a high potential for suppressed dc drift, and long-term reliability.     

High-speed source-heterojunction-MOS-transistor (SHOT) utilizing high-velocity electron injection

We have developed the source-heterojunction-MOS-transistor (SHOT), a novel high-speed MOSFET with relaxed-SiGe/strained-Si heterojunction source structures for quasi-ballistic or full-ballistic transistors. Using the band-offset energy at the source SiGe/strained-Si heterojunction, high velocity electrons can be injected into the strained-Si channel from the SiGe source region. For the first time, we have experimentally demonstrated that the transconductance is enhanced in SHOT for high applied drain voltage, compared to that of strained- and conventional silicon-on-insulator MOSFETs. We have also shown that the transconductance enhancement in SHOT depends on both the gate drive and the drain bias.     

Phase relations associated with the aluminum blast furnace: Aluminum oxycarbide melts and Al-C-X (X=Fe,Si) liquid alloys

The thermodynamic properties and the phase relations were evaluated and estimated for the Al-O-C, Al-Si-C, and Al-Fe-C systems which are important to understand the chemical behavior in an aluminum blast furnace. The mixing properties of binary liquid alloys, including metal-carbon systems, were represented by the Redlich-Kister equation. The properties of liquid Al−C and Si−C alloys were estimated so as to be consistent with their phase diagrams. The coefficients of Al−Fe and Fe−C liquids were evaluated from reported values for activity and enthalpy. The extrapolation to the higher order systems was made by Maggianu's method. The aluminum oxycarbide melt was represented by a subregular solution model. In the Al-O-C system, liquid alloy/oxycarbide melt equilibria were calculated and compared with earlier experimental results and estimates. Attempts were made to clarify the volatilization of aluminum oxycarbide melts, and also the carbidation of liquid aluminum alloys. An empirical correlation between the first terms of the Redlich-Kister equation for the enthalpies and the excess entropies was discussed.     

Millimeter-Wave Radiometer for the Measurement of Stratospheric ClO Using a Superconductive (SIS) Receiver Installed in the Southern Hemisphere

A new sensitive radiometer for atmospheric minor constituents has been developed by Nagoya University and the National Institute for Environmental Studies (NIES). The instrument equipped low-noise superconducting (SIS) mixer with a system noise temperature of ≈200K (SSB) at 204GHz. The SIS mixer is operated in a single side band mode with a side band ratio grater than 10dB by adjusting the two tunable backshorts of the mixer. Since any additional SSB filters are not necessary, we can simplify the quasi-optical system and reduce the standing waves which makes difficult to achieve a flat spectral baseline. We installed the observation system at Las Campanas Observatory, Chile in December 1999, and started the test observation from 2000 October. We have detected significant ClO emission at 204.3 GHz with an actual observation time of only 4 hours. This is the first detection of the ClO at 40km altitude from the mid-latitude region of the southern hemisphere. The Nagoya-NIES system has enabled continuous monitoring of ClO in the stratosphere with a time resolution of 4 or 5 hours.     

Beer brewing using a fusant between a sake yeast and a brewer's yeast

Beer brewing using a fusant between a sake yeast (a lysine auxotrophic mutant of sake yeast K-14) and a brewer's yeast (a respiratory-deficient mutant of the top fermentation yeast NCYC1333) was performed to take advantage of the beneficial characteristics of sake yeasts, i.e., the high productivity of esters, high tolerance to ethanol, and high osmotolerance. The fusant (F-32) obtained was different from the parental yeasts regarding, for example, the assimilation of carbon sources and tolerance to ethanol. A brewing trial with the fusant was carried out using a 100-l pilot-scale plant. The fusant fermented wort more rapidly than the parental brewer's yeast. However, the sedimentation capacity of the fusant was relatively low. The beer brewed using the fusant contained more ethanol and esters compared to that brewed using the parental brewer's yeast. The fusant also obtained osmotolerance in the fermentation of maltose and fermented high-gravity wort well.