Pupil function splitting method in calculating acoustic microscopic signals for elastic discontinuities

This paper deals with the output signals of scanning acoustic microscopes observing the elastic discontinuities on sample surface, and presents a new method of calculation. The formulation is based on the angular-spectrum method together with a ray-optical approximation. The key treatment is splitting of the pupil function into two parts. This method clarifies the image-forming factors in acoustic microscopy including large and fine fringes parallel to discontinuities. Calculation for an edge and a metal/ceramic joint showed good agreements with the experimental results.     

Synthesis of dithieno[2,3-b:3',2'-d]thiophenes-building blocks for cross-conjugated beta-oligothiophenes

Syntheses of annelated and functionalized beta-trithiophenes (dithieno[2,3-b:3',2'-d]thiophenes), building blocks for the helically annelated, cross-conjugated beta-oligothiophenes, are reported. UV-vis spectra reveal that the effect of octyl substituents on the onset of electronic absorption in annelated beta-trithiophenes is negligible compared to the effect of helical distortion in the higher beta-oligothiophenes.     

Development of near-infrared 35 fs laser microscope and its application to the detection of three- and four-photon fluorescence of organic microcrystals

Femtosecond near-infrared laser microscope was developed with a home-built cavity-dumped chromium:forsterite laser as a light source centered at 1.26 microm. Optimization of the pulse duration achieved 35 fs fwhm at the sample position of the microscope after passing through a 100x objective. This system was applied to the detection of multiphoton fluorescence of some organic microcrystals. Excitation intensity dependence and the interferometric autocorrelation detection of the fluorescence clearly demonstrated that simultaneous three- and four-photon absorption processes are responsible for the production of the excited state for perylene and anthracene microcrystals, respectively. The spatial resolution along the optical axis and its dependence on the order of the multiphoton process were also discussed.     

Picosecond 266 nm photolysis of neat liquids: Solvated electron formation in water and alcohols

The picosecond time-resolved absorption spectra of water and some alcohols were measured by means of 266 nm multiphoton photolysis. The formation time     

Development of a new type of electric off-road vehicle powered by microwaves transmitted through air

Needless to say, we are now facing a critical state in the global environment, i.e. global warming. We have to change our way of thinking and our economic systems from those dependent on fossil resources to those dependent on renewable energy resources, such as solar energy. In our field of research, electric vehicles are considered the best choice for reducing carbon dioxide emissions. A battery is not an adequate energy source for electric vehicles, because batteries quickly get depleted because of its low energy and power density. A fuel cell is a more favorable alternative to the battery; however, it has large mass and can only replace the internal combustion engine, but the power transmission mechanisms are still necessary. The new concept of an electric off-road vehicle proposed here is entirely different from those mentioned above. The vehicle has neither a combustion engine nor a battery but only electric motors. Energy to drive the motors is transmitted through air as microwaves at 2.45 GHz. This technology was developed at the Research Institute for Sustainable Humanosphere, Kyoto University, as a method for transmitting electricity from a large-scale solar power station (SPS) orbiting in space to the Earth. We have constructed some models of electric off-road vehicles and investigated their adoptability to microwave power transmission. In this paper, some experimental results on the use of microwave power transmission for powering the vehicles are presented, and some problems such as low energy transmission efficiency are also discussed.     

A nanometer-sized high-spin polyradical: poly(4-phenoxyl-1,2-phenylenevinylene) planarily extended in a non-Kekulé fashion and its magnetic force microscopic images.

A pi-conjugated, but non-Kekulé- and nondisjoint-type poly(1,2-phenylenevinylene) network bearing 4-substituted di-tert-butylphenoxyls was synthesized through a one-pot polycondensation of the star-shaped subpart and the subsequent oxidation, which was persistent even at room temperature. The polyphenoxyl radical with a spin concentration of 0.4 displayed an average S of 10/2. The polyradical with the molecular weight of 3.2 x 10(4) gave a disklike image of ca. 35 x 0.6 nm with both an atomic and a magnetic force microscopy: the molecular image was examined as a nanoscale and single-molecular-based magnetic dot.     

Ladderlike ferromagnetic spin coupling network on a pi-conjugated pendant polyradical

A poly(9,10-anthryleneethynylene)-based polyradical with two pendant stable phenoxyls in one anthracene skeleton was newly synthesized via polymerization of the corresponding bromoethynylanthracene monomer using a Pd(0) catalyst. The average molecular weight of the polymer reached M(n) = 5 x 10(3) and was soluble in common organic solvents. The polyradical was prepared from the corresponding hydroxyl precursor polymer and was appropriately stable at room temperature. The ESR spectrum of the corresponding monomeric radical suggested an effectively delocalized spin density distribution on the backbone anthracene. The magnetization and the static magnetic susceptibility of the polyradical were measured using a SQUID magnetometer. The large average spin quantum number (S = (5)/(2)) of the polyradical indicated that the ferromagnetic spin coupling network of the polyradical had spread throughout the pi-conjugated chain and that it was considerably insensitive to spin defects.     

Evaluation of asymmetrical structure dialysis membrane by tortuous capillary pore diffusion model

The tortuous capillary pore diffusion model (TCPDM) has been used for estimating diffusive and pure water permeability from simple structure parameters such as pore diameter, surface porosity, wall thickness and tortuosity. The validity of this model for evaluation of homogeneous membrane has been already confirmed. Recently, there is a trend toward the use of asymmetrical dialysis membranes made of synthetic polymer such as poly(acrylonitrile) (PAN), polysulfone (PS) and a polyethersulfone polyarylate (PEPA) blend polymer. The purpose of the present study is to apply the TCPDM to evaluation of commercially available hollow-fiber dialysis membranes with asymmetrical structures by simplifying them to a double-layer membrane. The TCPDM is capable of estimating pore tortuosity of asymmetrical dialysis membranes having skin and supporting layers from data on membrane thickness, pore diameter, pure water permeability and water content. Values for diffusive permeability obtained by the TCPDM are in a good agreement with experimental data. This TCPDM model is useful for evaluation of not only homogeneous membrane but also asymmetrical membrane.