Anderson localization and superconducting transition temperature in two-dimensional systems

Effects of the Anderson localization on superconducting transition temperature T_c are examined by calculating a two-electron propagator K rigorously up to 0[(?_Fτ₀)^?1ln(Tτ₀)], where τ₀ is the electron life time due to impurity scattering and ?_F the Fermi energy. The results show that in K the pair-breaking terms cancel out among themselves exactly and the remaining terms which contribute to the correction to the density of states and to the renormalization of electron-electron interaction by impurity scattering lead to the changes in T_c of 0[{ln(Tτ₀)}²] and of 0[{ln(Tτ₀)}³], respectively.     

Estimating function with asymptotic bias and its estimator

We introduce the estimating function with asymptotic bias and investigate the asymptotic behavior of the estimator based on it by using their relationship. The estimator based on the estimating function with asymptotic bias has the asymptotic normality with asymptotic bias. We show that this theory has several interesting applications in practical statistics.     

Studies on the syntheses of heterocyclic and natural products. Part 979. Attempted asymmetric synthesis of yohimbol by photocyclization of the enamide

An asymmetric synthesis of yohimbane alkaloid has been attempted by the photolysis of the corresponding enamide ( 3 ) as a key reaction.     

NMR studies of chlorinated poly(vinyl chloride) and polybutadiene

Molecular structures of chlorinated poly(vinyl chloride) and polybutadiene have been studied by high resolution NMR. The spectra of the chlorinated polymers give broad signals. New peaks appear in the lower fields of the ? CH₂? and ? CHCl? groups with increasing chlorine content. The chlorination of poly(vinyl chloride) takes place predominantly on ? CH₂? rather than on ? CHCl? , e.g., a 70% chlorinated polymer has about 10 mole-% of ? CCl₂? groups. Polybutadiene reacts first with chlorine by addition to give a head-to-head poly(vinyl chloride), and then the substitution of the hydrogen atom takes place. Chlorinated polybutadiene with 70% Cl has about 18 mole-% of ? CCl₂? . The multiplets characteristic of spin-spin couplings in the spectrum of the original poly(vinyl chloride) are still observed in that of the highly chlorinated product. This fact shows that a considerable number of poly(vinyl chloride) sequences of certain lengths persist in the highly chlorinated polymer.     

Application of the opal-glass method for ion-exchanger spectrophotometry

A simple and precise method for the measurement of the net absorbance of colored species sorbed on ion-exchange resins is reported. Identical opal-glass plates are inserted on the transmission sides of both the sample-cell and blank-cell compartments of the spectrophotometer. Absorbances of sample-resin layers are measured against a blank-resin layer as reference. Scattering effects caused by resin particles are almost eliminated by using opal glass. For the determination of chromium(VI) with diphenylcarbazide reproducible calibration lines were obtained without tedious compensation methods.     

Thermal study of the interaction of crystalline surfactant with water; The dioctadecyldimethylammonium chloride-water system

Dioctadecyldimethylammonium chloride (DOAC) was completely dehydrated under high vacuum and at a temperature above its transition temperature (96.7°C) which was first discovered by us. Thermoanalytical studies on DOAC-water systems indicate that two successive phase changes of coagel → gel and gel → liquid crystal appear due to the increasing structural disorders of polar head groups and hydrocarbon chains, respectively. Furthermore, it is revealed that three types of water exist, i.e., bound, intermediate and free. On the basis of a bilayer-lamellar structure model, a predominant role of the intermediate water in these transitions is pointed out.     

Nonlinear piezoelectricity in PZT ceramics for generating ultrasonic phase conjugate waves

We have succeeded in the generation of acoustic phase conjugate waves with nonlinear PZT piezoelectric ceramics and applied them to ultrasonic imaging systems. Our aim is to make a phase conjugator with 100% efficiency. For this purpose, it is important to clarify the mechanism of acoustic phase conjugation through nonlinear piezoelectricity. The process is explained by the parametric interaction via the third-order nonlinear piezoelectricity between the incident acoustic wave at angular frequency omega and the pump electric field at 2 omega. We solved the coupling equations including the third-ordered nonlinear piezoelectricity and theoretically derived the amplitude efficiency of the acoustic phase conjugation. We compared the efficiencies between the theoretical and experimental values for PZT ceramics with eight different compositions. Pb[(Zn1/3Nb2/3)(1 - x)Tix]O3 (X = 0.09, PZNT91/9) piezoelectric single crystals have been investigated for high-performance ultrasonic transducer application, because these have large piezoelectric constants, high electrical-mechanical coupling factors and high dielectric constants. We found that they have third-order nonlinear piezoelectric constants much larger than PZT and are hopeful that the material as a phase conjugator has over 100% efficiency.     

Isomerization of DNA-bound distilbazolium ligand induced by electron transfer from photoexcited tris(1,10-phenanthroline)Ru(II)

The ability of the DNA duplex to behave as an efficient organized medium for cis-trans isomerization induced by electron transfer (ET) has been explored. Isomerization studies, luminescence quenching and DNA photocleavage assays show that photoexcited Ru(1,10-phenanthroline [phen])3(2+) transfers an electron to E,Z1,4-bis[2-(1-methylpyridinium-4-yl)vinyl]benzene (E,Z pMPVB), which subsequently undergoes one-way isomerization to E,E pMPVB. The unusual feature of the system is manifested by the lack of friction that is usually imposed on the photoisomerizable ligand by highly organized media. The apparent rate of ET in DNA increases when compared with the homogeneous solution. However, after correction for the local concentration of the reagents onto the biopolymer, the rate constant becomes independent of the DNA concentration and is at least 4 x 10(2) times smaller than that in the homogeneous aqueous solution. Using the photoinduced isomerization system, a large enhancement in the efficiency of single-strand break formation was found in plasmid DNA over that for Ru(phen)3(+2) alone using irradiation at lambda > 480 nm.