Plasma heating by lower hybrid resonance

Experimental results are presented for the dispersion relation of the resonance and heating plasma by rf field at the frequency near the hybrid ion electron resonance.     

Search for the Decay K L0-->pi0nu nu[over

We performed a search for the K L0-->pi0nu nu[over] decay at the KEK 12-GeV proton synchrotron. No candidate events were observed. An upper limit on the branching ratio for the decay was set to be 6.7 x 10(-8) at the 90% confidence level.     

Mass spectra of the bitter principles fromPicrasma ailanthoides Planchon

The mass spectra of several bitter principles isolated from Picrasma ailanthoides Planchon (= P. quassioides Bennett) have been measured and characteristic fragmentation patterns useful for structure elucidation shown. The mass spectra of some related compounds are also described.     

Nonlinear amplitude osçillations of absolutely unstable electrostatic ion cyclotron waves in an ion beam-plasma system

We have observed experimentally the amplitude oscillations of absolutely unstable electrostatic ion cyclotron waves in an ion beam-plasma system due to nonlinear interaction between the beam ions and electrostatic ion cyclotron waves.     

Pseudomorphic InGaAs quantum-wire FETs with negative differential resistance

Pseudomorphic trench-type InGaAs/InAlAs quantum-wire field-effect transistors (QWR-FET) are realized by selective molecular beam epitaxy. The pseudomorphic QWR-FET has a negative differential resistance (NDR) effect with a low source–drain voltage (0.3 V). The NDR spectra are clearly observed in the 50–220 K temperature range. The operating current of the pseudomorphic QWR-FET is twice that of a lattice-matched QWR-FET, and this is thought to be due to the higher electron mobility.     

Evidence for a narrow S = +1 baryon resonance in photoproduction from the neutron

The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54+/-0.01 GeV/c(2) with a width smaller than 25 MeV/c(2) and a Gaussian significance of 4.6sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uuddsmacr;) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.     

The formation of large scale reconstructed images through the use of holograms

We propose and demonstrate a method which constructs large size multicolor images using a holographic technique in limited spaces, i.e., tunnels. A traffic sign image of the same size and color as an actual traffic sign board is displayed using many comparative small holograms. Each hologram is composed of a single computer generated hologram (CGH). Though it was necessary to make many CGHs, we have shortened the hologram production time by putting a reconstructed image on long distance, and using many reconstruction sources. Moreover, though cross-talk images are caused in a color reconstruction, by adjusting the optical system it is possible to make sure that drivers see only the appropriate image. Many holograms function as one big hologram, and it has been confirmed that a large reconstructed image can be displayed in a limited space.     

Intramolecular migration of long chain acyl group of enacyloxin IIa methyl ester

Enacyloxin IIa methyl ester in non-protic solvent gave rearranged product in acidic conditions such as surface of TLC plate of silica gel or by treatment with a catalytic amount of p-toluenesulfonic acid. On the other hand, such a rearrangement did not occur in polar protic solvent. The structure of the rearranged product was elucidated as 4-acyl analog of the cyclohexane ring.     

Prediction of endocrine disruptors based on a new structure-activity relationship for sex and environmental hormones using chemical hardness concept.

Classification of the relationship between electronic structures and biological activities of endocrine disruptors (so-called environmental hormones) was attempted using the parameters of absolute hardness (eta), absolute electronegativity (chi), and global softness (S), approximately defined as eta=1/2(epsilonLUMO-epsilonHOMO), chi=-1/2(epsilonHOMO+ epsilonLUMO), and S=1/eta, respectively, based on the hardness concept. The strength of binding affinity and toxicity of the chemicals were approximately proportional to the absolute hardness, and laterally toxic chlorinated PCDDs, PCBs, and DDTs are classified as chemically soft. Here we found that the electronic structures of environmental hormones can be classified into four main groups: 17beta-estradiol type (group I), testosterone type (group II), thyroxine type (group III), and HCH (hexachlorocyclohexane) type (group IV). Therefore, if we can predict the coordinate (chi, eta) of the electronic structure of one chemical on the eta-chi activity diagram, we would be able to predict the receptor with which the chemicals (environmental hormones) interact. For instance, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is classified in group II, therefore, it would bind with the thyroid receptor more than the estrogen receptor (group I). It appears that dibutyl phthalate would not interact with estrogen receptor because it does not belong to group I. In addition, the coordinates of these four groups do not complementarily overlap with the electronic structures of 20 natural amino acid residues. The eta-chi activity diagram is a new tool for the prediction of the toxicity and biological activity of environmental hormones.     

pH Dependence of the size and crystallographic orientation of the gold nanoparticles prepared by seed-mediated growth

The effect of the pH of the growth solution on the size and crystallographic orientation of gold nanoparticles (GNPs) was studied during the course of the preparation of surface-confined spherical GNPs following a two-step protocol (electrochemical and chemical). GNPs were first electrodeposited onto a clean glassy carbon (GC) electrode and these GNPs were used as seeds. Seed-mediated growth of the electrodeposited GNPs was performed in a solution of H[AuCl(4)] at various pHs (5.0 to 0.5) using NH(2)OH as a reducing agent. The thus-prepared GNPs were characterized by electrochemical, UV-visible absorption spectral, SEM, and TEM studies. The nucleation (i.e., formation of the new seeds) was found to dominate over growth (i.e., enlargement of the seed particles) process at higher pH during NH(2)OH seeding, whereas only growth was recognized at low pH (0.5). Nonspherical byproducts were noticed when the seed-mediated growth was performed at higher pHs, but at pH 0.5 only spherical GNPs were observed. The present method provides a way out for the preparation of GNPs with homogeneous shape resolving the problem of simultaneous formation of nonspherical byproducts during the seed-mediated growth as well as for the preparation of GNPs with a Au(111) facet ratio as high as 97%. On the basis of the obtained results, the mechanism of the growth process at low pH is also discussed. Interestingly, an enhanced electrochemical response was obtained for the oxidation of H(2)O(2) using the GNPs prepared at pH 0.5.