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61.
62.
63.
Miyano S. Numata K. Sato K. Yabe T. Wada M. Haga R. Enkaku M. Shiochi M. Kawashima Y. Iwase M. Ohgata M. Kumagai J. Yoshida T. Sakurai M. Kaki S. Yanagiya N. Shinya H. Furuyama T. Hansen P. Hannah M. Nagy M. Nagarajan A. Rungsea M. 《Solid-State Circuits, IEEE Journal of》1995,30(11):1281-1285
An 8 Mb embedded DRAM has been developed. The salient feature of this embedded DRAM is page fault tolerance. Accessing across different pages can be performed using a minimum column cycle. This feature is achieved by placing a data latch and a transfer gate between the bit line sense amplifier and the column select gate. This DRAM can be reconfigured as separated 2 Mb units when it is embedded as a macro cell of an ASIC library 相似文献
64.
Shunichi Matsuno Hiroshi Kamimura 《Journal of Superconductivity and Novel Magnetism》1994,7(3):517-519
In order to clarify the electronic structure of the electron-doped superconducting material Nd2?xMxCuO4, we have performed a first-principle band structure calculation for the matrix material Nd2CuO4. We find that doped electrons can be accommodated in both the Cu 4s and 4p z conduction bands provided that the Cu 3dx2?y 2 band splits into two bands, i.e., the upper and lower Hubbard bands by the strong correlation. Based on this electronic structure, we have calculated the Hall coefficient of the Nd system and have shown for the first time that the sign of the Hall coefficient is negative, coinciding with the experimental result in the low-concentration case. In the overdoped region above x=0.18, the dopant electrons occupy not only 4s and 4p z bands but also the upper Hubbarddx 2?y 2 so that the Hall coefficient changes its sign from negative to positive. 相似文献
65.
T. Ōgushi Y. Hakuraku Y. Honjo G. N. Suresha S. Higo Y. Ōzono I. Kawano T. Numata 《Journal of Low Temperature Physics》1988,70(5-6):485-492
A possible high-T
c
c
superconductivity in a La-Sr-Nb-O film is reported. Onset of the resistive transition is at a temperature (T
co
) of 315 K, with a zero-resistance state at a temperature (T
ce
) of 255 K. Diamagnetization of about 5% that of the pure Nb superconductor and a noticeable current dependence ofT
co
andT
ce
are observed. The yield probability of this film is 50%. The characteristics were observed even 17 days after preparation. However, a thermal cycle (cooling and warming) of more than ten cycles gradually deteriorates the characteristics. 相似文献
66.
The crystal structure of thermostable mutants of chimeric 3-isopropylmalate dehydrogenase, 2T2M6T 总被引:1,自引:0,他引:1
Sakurai Masahiro; Moriyama Hideaki; Onodera Ko; Kadono Shojiro; Numata Koichi; Hayashi Yoko; Kawaguchi Jitsutaro; Yamagishi AkJhiro; Oshima Tairo; Tanaka Nobuo 《Protein engineering, design & selection : PEDS》1995,8(8):763-767
A chimeric 3-isopropylmalate dehydrogenase (IPMDH), 2T2M6T,was produced by replacing the amino acid sequences of the Thermusthermophilus enzyme with those of the Bacillus subtilis enzymefrom residues 75 to 113. Decreased thermostability of the chiaiericenzyme was recovered by either evolutionary engineering (I93L)or site-directed mutagenesis (S82R). The 3-D structures of themutants have been determined by X-ray diffraction at 2.1 Åresolution. Although S82R was refined routinely, (I93L) requiredthe preliminary rigid-body refinement of each domain. The X-factorswere reduced to 0.18 for both mutants. Removal of the unfavorabletorsion angle at isoleucine 93 may have made I93L more thermostablethan 2T2M6T. In the case of S82R, the replaced arginine residuecontributed to the extra hydrogen bond with water molecules.The large replaced residue decreased the entropy of the solvent,which may have caused the improvement in enzyme thermostability.Denatu ration by heating may be interpreted from these structuralresults. 相似文献
67.
Effective chain extenders for linear polyesters were investigated among some bis-heterocycles, which were capable of coupling carboxyl terminals of the polyesters through addition reaction. Consequently, 2,2′-bis(2-oxazoline), 2,2′-bis(5,6-dihydro-4H-1,3-oxazine) and N,N′-hexamethylenebis(carbamoyl-2- oxazoline) were found to be the most effective chain extenders. Starting from a poly(ethylene terephthalate) (PET) having intrinsic viscosity ([η]) of 0.66 and carboxyl content (CV) of 46 eq/106 g, one could obtain polyesters with [η] of above 1.0 and CV of below 5 eq/106 g in the presence of the chain extenders. Typical reaction condition for the coupling of PET was heating PET under atmospheric nitrogen above its melting temperature with 0.5 mol % of a chain extenders only for several minutes. Bis-2-thiazolines showed no effect under the condition investigated, while in case of bis-2-imidazolines definite degradation was observed. Bis-N-acylaziridines and bisiminocarbonates resulted in some gell formation, indicative of side reactions. 相似文献
68.
A new type of thermosetting resin can be obtained from solventless varnishes composed of polyfunctional isocyanates and epoxides. The IR spectra show that the cured resins have isocyanurate and oxazolidone rings in their chemical structure, hence their name, isocyanurate–oxazolidone resins. The viscoelastic behavior of the cured resins can be varied considerably by selecting an appropriate reactant species and changing the equivalent ratio of the isocyanate and epoxy groups in the varnishes. Three relaxations, labeled α, β, and γ, characterize their dynamic mechanical spectra. The α-dispersion is due to the glass transition, the β-dispersion, to local mode motions of the backbone chains of resins, and the γ-dispersion, to the molecular motions of long alkyl chains. If certain additives are mixed into the varnishes before curing, microphase separation takes place during the reactions. The resins finally obtained have a peculiar physical structure in which rubber particles are dispersed throughout a matrix phase as confirmed by scanning electron-microscopic analysis and viscoelastic behavior. 相似文献
69.
The significance of the geminal dimethyl group at C-6 of (+)-trans-veibenyl acetate (Ib), a sex pheromone mimic of the American cockroach, was investigated. Our interest was first directed to eliminating either methyl group of the geminal dimethyl group. Consequently, alcohols (IIIa and IVa) possessing a monomethyl group at C-6 were successfully obtained. Acetate (IVb) and propionate (IVc) of alcohol (IVa) possessing only a C-9 methyl group induced sex pheromonal activity at the 0.5 (IVb) and 0.02 mg (IVc) dose levels, respectively, while acetate (IIIb) of a alcohol (IIIa) with only C-8 methyl group was inactive. Alcohol (Va), which has an ethyl group at the C-6 instead of C-9 methyl, was also synthesized and converted into its acetate (Vb), which showed no activity. From these results, the significance of the dimethyl group is discussed relative to spatial requirements of the molecule for the receptor space. The M/F ratio in EAG was also evaluated for the synthesized esters. The M/F ratio index represented well the potency of pheromonal activity. 相似文献
70.
Mass spectrometry was used to monitor in-situ gaseous species that were generated at the head-disk interface (HDI) in a high vacuum. It was found that the end groups of the lubricants significantly affected the wear durability at the HDI; piperonyl (–CH2-phe = (O)2 = CH2) terminated Fomblin AM3001 lubricant exhibited longer life than hydroxyl (–OH) terminated Fomblin ZDOL lubricant. The continuous removal of the lubricants resulted in a continuously increasing friction coefficient. Further, the characteristics of tribochemical reactions of the lubricants (Fomblin Z series) with different end groups was investigated in details using Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) just after the sliding tests. It was found that the decomposition of the end groups was more significant than that of the backbone. The lubricants terminated with the following groups showed the following order of increasing decomposition: –CH2O-CH2-phe = (O)2 = CH2 (AM3001), –CH2OH (ZDOL) < –CH2OCH2CH(OH)CH2OH (Z Tetraol) < –CH2(OCH2CH2)nOH (ZDOL-TX), –COOH (Z Diac). The decomposition of the lubricants appeared to start from the end groups. 相似文献