A 90-nm low-power 32-kB embedded SRAM with gate leakage suppression circuit for mobile applications

In sub-100-nm generation, gate-tunneling leakage current increases and dominates the total standby leakage current of LSIs based on decreasing gate-oxide thickness. Showing that the gate leakage current is effectively reduced by lowering the gate voltage, we propose a local dc level control (LDLC) for SRAM cell arrays and an automatic gate leakage suppression driver (AGLSD) for peripheral circuits. We designed and fabricated a 32-kB 1-port SRAM using 90-nm CMOS technology. The six-transistor SRAM cell size is 1.25 /spl mu/m/sup 2/. Evaluation shows that the standby current of 32-kB SRAM is 1.2 /spl mu/A at 1.2 V and room temperature. It is reduced to 7.5% of conventional SRAM.     

A GaAs MESFET with a partially depleted p layer for SRAMapplications

A GaAs MESFET with a partially depleted p layer that has a specific application to SRAMs has been developed. The short-channel effect is well suppressed for gate lengths down to 0.5 μm by a rather dense p layer buried under the channel. Its acceptor ion dose is as high as 2×10¹² cm^-2, which corresponds to a partially depleted condition. As for applications for SRAMs, it is possible to attain fully functional 7-ns 4-kb SRAMs that are operative at 75°C by using the FET with a 1-μm gate. A chip yield of 22% has been achieved in a 3-in wafer     

High-performance gel filtration of water-soluble samples on polyvinyl alcohol columns

The chromatographic behaviour in aqueous solution of pullulans, polyethylene glycols, peptides and proteins with different molecular weights on newly developed polyvinyl alcohol columns (Asahipak GS column series: GS-310, GS-320, GS-510 and GS-520) has been investigated. Pullulans and polyethylene glycols eluted according to the gel filtration mode, so both series of compounds produced almost equal calibration curves for GS-310 and GS-320 and for GS-510 and GS-520; the exclusion limits on GS-310 and GS-320 and on GS-510 and GS-520 were found to be ca. 40,000 and 300,000, respectively. Peptides and proteins were found to adsorb slightly on the columns. However, the plots of the elution volumes against the logarithm of the molecular weights for many of the substrates tested gave rise to the linear calibration curves. Recovery of several crude proteins was also studied for the columns and high values were obtained (81–100%). The effects of changes in the flow-rate, temperature and concentration of electrolytes added to the eluents, on the retention of all four types of compound are also reported.     

All-optical phase modulation in a traveling wave semiconductorlaser amplifier

A novel all-optical phase modulation and wavelength conversion has been demonstrated in a traveling wave semiconductor laser amplifier. Even though the optical gain modulation caused by the saturation effect in a traveling wave semiconductor laser amplifier is sensitive to the signal wavelength, the optically controlled phase modulation is relatively independent of the signal wavelength     

(6Li,d) reactions on 24Mg and 26Mg at 73 MeV

The ^{24, 26}Mg(⁶Li, d)^{28, 30}Si reactions have been studied at 73 MeV bombarding energy. The angular distributions were analyzed with exact finite-range distorted wave Born approximation calculations assuming a direct α-cluster transfer. Extracted spectroscopic strengths leading to low-lying levels of ²⁸Si and relative spectroscopic strengths between transitions to ²⁸Si and ³⁰Si ground states are consistent with those previously obtained by several α-transfer reactions. Many strongly populated levels have been observed at E_x ? 10 MeV for ²⁸Si. A marked similarity was found between the deuteron spectrum and the ²⁴Mg(α, α)²⁴Mg excitation function in this excitation energy region. A brief comparison of the present α-transfer results with previous two-nucleon transfer data leading to ^28,30Si is also presented.     

Synthesis of fluorinated chitin derivatives via enzymatic polymerization

Synthesis of fluorinated chitin derivatives has been achieved using chitinase from Bacillus sp. as a catalyst. 6'-Fluoro- (1a), 6-fluoro- (1b) and 6,6'-difluoro- (1c) chitobiose oxazoline derivatives were newly prepared as TSAS monomers for chitinase. Ring-opening polyaddition of these monomers proceeded effectively at pH 8.0-9.0 and 30-40 degrees C, giving rise to alternatingly 6-fluorinated chitin derivatives (2a and 2b) from 1a and 1b, and fully 6-fluorinated chitin derivative (2c) from 1c under total control of regioselectivity and stereochemistry. XRD measurements revealed that polysaccharides 2a and 2b had crystalline structures similar to that of alpha-chitin. [reaction: see text]     

On the Boolean connectivity problem for Horn relations

Gopalan et al. studied in [P. Gopalan, P.G. Kolaitis, E.N. Maneva, C.H. Papadimitriou, The connectivity of Boolean satisfiability: computational and structural dichotomies, in: Proceedings of the 33rd International Colloquium on Automata, Languages and Programming, ICALP 2006, 2006, pp. 346-357] and [P. Gopalan, P.G. Kolaitis, E.N. Maneva, C.H. Papadimitriou, The connectivity of Boolean satisfiability: computational and structural dichotomies, SIAM J. Comput. 38 (6) (2009) 2330-2355] connectivity properties of the solution-space of Boolean formulas, and investigated complexity issues on the connectivity problems in Schaefer’s framework. A set S of logical relations is Schaefer if all relations in S are either bijunctive, Horn, dual Horn, or affine. They first conjectured that the connectivity problem for Schaefer is in P. We disprove their conjecture by showing that there exists a set S of Horn relations such that the connectivity problem for S is -complete. We also investigate a tractable aspect of Horn and dual Horn relations with respect to characteristic sets.     

Production of hyperpolarized nuclei for MRI

The project in producing the hyperpolarized ³He and ¹⁹F are addressed in pursuit of radiation free medical diagnosis. The program for production of the hyperpolarized ³He by the brute force method with the Pomeranchuk cooling and the rapid melting of the solid 3He started a few years ago, and is still on the way, while a new program for production of the hyperpolarized ¹⁹F by means of the PHIP (ParaHydrogen Induced Polarization) has just got started. Particular attention is placed upon a new idea of the hyperpolarization catalyst to be used for ¹⁹F.