Experimental assessment of quasi-binary picture of thermotropics: induced smectic A phase in 7CB-n-heptane system

Quasi-binary (QB) picture of thermotropics, which regards a neat thermotropic liquid crystal as a binary system consisting of (semi)rigid core and molten alkyl chain, was assessed experimentally for the most famous (and representative) thermotropic mesogenic series nCB. By adding n-heptane as solvent, the smectic A phase was induced in 7CB-n-heptane system. Small angle x-ray diffraction showed that the QB picture holds not only in the phase behavior but also in the structure. It is suggested that the melting of 8CB and 9CB to isotropic liquid via smectic and nematic liquid crystals can be understood as a thermotropic-lyotropic crossover.     

A system LSI memory redundancy technique using an ie-flash(inverse-gate-electrode flash) programming circuit

A new memory redundancy technique using inverse-gate-electrode flash (ie-flash) memory cells has been developed. The ie-flash can be fabricated by the conventional logic CMOS process, so no additional processes are necessary in using it in system LSIs, and it can be programmed by logic testers. We enhanced the reliability of ie-flash by using some circuits, increasing reliability to endure practical use. This new redundancy technique was successfully implemented in the cache memories of a 32-b RISC microprocessor     

Spektroskopische Untersuchung der Prim?rprozesse bei der strahleninduzierten Polymerisation von 1,3-Butadien

Ohne Zusammenfassung     

Expulsion of the CHO radical from the molecular ion of homochromones

For some homochromones, it was confirmed by labelling C-9 with deuterium that the CHO radical expelled from the molecular ion contains either the methine hydrogen or one of the methylene hydrogens of the cyclopropane ring. The origin of the CO group in the expelled CHO radical was also inferred, and a plausible mechanistic interpretation is presented.     

SRAM Circuit With Expanded Operating Margin and Reduced Stand-By Leakage Current Using Thin-BOX FD-SOI Transistors

The deterioration of operating margin and increasing leakage current in SRAM are becoming critical problems with the advance of process scaling. To solve these problems, we propose a low-power SRAM circuit using thin buried-oxide fully depleted silicon-on-insulator transistors. The back-gate bias is introduced to the SRAM circuits and acquires high operating margin and high-speed operation under low supply voltage. The leakage current in stand-by state is reduced. This SRAM achieves 30% faster writing time under low-voltage operation and 90% less stand-by power     

Mössbauer spectroscopic study on polyacetylene doped with iodine

The ¹²⁹I Mössbauer effect has been applied to polyacetylene films of cis-(CHI_0.23)_x as prepared and cis-(CHI_0.20)_x led under dynamic evacuation. It has been clarified that both films contain linear I^?₅ and I^?₃ with symmetric charge population and that the fraction of I^?₃ increases after evacuation. The mechanism of electrical conductivity in iodine-doped polyacetylene has been discussed on the basis of the chemical form and the dynamic behavior of the anion species.     

Effect of hydrostatic pressure on the Raman spectrum of anatase (TiO2)

Raman spectra of anatase have been investigated under pressures up to 60 kbar and at room temperature. A pressure-induced phase transition is observed at pressures above 25.6 kbar. The 197 cm^-1 mode (at 1 atm.) of six Raman active modes exhibits anomalous pressure dependence in which the frequency decreases with increasing pressure. This mode may be significant in the phase transition. The remaining modes show usual behavior.     

Photoreactive fluorinated polyimide protected by a tetrahydropyranyl group (THP) based on photo-induced acidolysis

A polyimide (6F-THP) with a tetrahydropyranyl group (THP) in its side chain has been synthesized. The THP group exhibits a high acidolysis rate in this polymer's film. This rate was faster than that of a tertbutoxycarbonyl group (t-BOC), which has been previously reported [1]. Furthermore, the deprotected fluorinated polyimide (6FDA-AHHFP) became soluble in an aqueous base due to the presence of a hydroxyl group attached to the phenyl group of the diamine segment. The polyimide thus provides high performance as a photopolymer when used in conjunction with a photoacid generator after the post-exposure baking process (PEB). The photoacid generators used in this study were p-nitrobenzyl-9,10-dimethoxyanthoracene-2-sulfonate (NBAS) and diphenyliodonium-9,10-dimethoxyanthoracene-2-sulfonate (DIAS). The quantum yields of photodissociation and photoacid generation were also measured. The photoacid-generating quantum yields closely corresponded to the photosensitivities of the photoreactive polyimide system. It was confirmed that the THP group was easily deprotected even in the 6F-THP film with p-toluenesulfonic acid as a model acid catalyst. The activation energy of the THP deprotection reaction was determined to be 12.8 kcal/mol (19.5 kcal/mol in the case of t-BOC). The relationships between the THP deprotecting rate constant (k_d) and acid molecular size and between k_d and polyimide structure were further investigated.