Efficient vibrational relaxation of O2(X 3sigma(g)-, nu = 8) by collisions with CF4

A laser flash photolysis-laser-induced fluorescence (LIF) technique has been employed to study the relaxation kinetics of vibrationally excited O2(X 3sigma(g)-. The time-resolved LIF excited B 3sigma(u)(-)-X 3sigma(g)- system has been recorded and analyzed by the integrated-profiles method. The rate coefficient for vibrational relaxation of O2(X 3sigma(g)-, nu = 8) by collisions with CF(4), [1.4 +/- 0.3(2sigma)] x 10(-11) cm3 molecule(-1) s(-1), indicates that CF4 is an efficient relaxant of O2(X 3sigma(g)- and that the propensity rule for O2 relaxation suggested by Mack et al. (J. A. Mack, K. Mikulecky and A. M. Wodtke, J. Chem. Phys., 1996, 105, 4105) has been observed experimentally.     

Analog Metal-Oxide-Semiconductor Integrated Circuit Implementation of Approach Detection with Simple-Shape Recognition Based on Visual Systems of Lower Animals

We proposed an analog network for motion detection of an approaching object with simple-shape recognition based on the visual systems of lower animals. Locusts can detect an approaching object by performing a simple process in a descending contralateral motion detector (DCMD) existing in their brain, which senses the increase in size and expansion velocity of the image projected on a retina just before collision. The responses correspond to the approaching velocity and direction. Frogs can recognize a simple shape by performing a simple process in a tectum and thalamus existing in their brain based on retinal information; this is called the Ewert von Seelen model. The proposed network was constructed with simple analog metal-oxide-semiconductor (MOS) circuits. Simulation results with a simulation program with integrated circuit emphasis (SPICE) showed that the network was able to detect the approaching velocity and direction, and also recognized simple shapes such as a circle, square, triangle and rectangle.     

Samarium(II)-induced ring-expansion reaction of 1,2-cyclobutanedicarboxylates to produce cyclopentanones

Novel ring-expansion reaction of 1,2-cyclobutanedicarboxylates with Sm(II) in the presence of HMPA with a catalytic amount of methanol was found to provide 2-oxocyclopentanecarboxylates.     

Novel determination system for urea in alcoholic beverages by using an FIA system with an acid urease column.

A novel determination method for urea using an acid urease column-FIA system was developed, and the system was applied to the determination of urea in rice wine. This novel FIA system was characterized by CO2 detection due to the property of acid urease and by a microfluidic gas-diffusion device with the use of an ultra-thin hollow fiber membrane. A biosensing system fabricated in this study was assembled with a double-plunger pump, a sample-injection valve, an immobilized acid urease column as a recognition element for the assay of urea, a gas-diffusion unit, and a flow-type spectrophotometer. The gas-diffusion unit consisted of a double-tubing structure in which the outer tubing was made of PTFE (i.d. 1.0 mm; o.d. 1.5 mm) and the inner tubing was of porous PTFE (i.d. 0.19 mm; o.d. 0.25 mm). Standard urea solutions (20 microl) were measured through monitoring variations in the absorbance of a coloring agent solution resulting from a pH shift due to carbon dioxide molecules being enzymatically generated. A wide and linear relationship was obtained between the concentration of urea (16 microM - 1.0 mM) and the change in absorbance. This FIA system has great advantages that the system did not suffer from ammonia and ethanol in samples. This system, armed with a microfluidic gas-diffusion device, was applicable to the determination of various substrates of many kinds of decarboxylase, amino-acid oxidase, and amino-acid oxygenase, producing CO2 and NH3 molecules.     

Synthesis and Properties of Hydrophilic Copolymers Containing 5-Fluorouracil,Thymine, or Adenine

Hydrophilic copolymers containing 5-fluorouracil (5-FU), thymine, or adenine were prepared by the free-radical copolymerization of methacryloyl-type monomers containing them with water-soluble vinyl monomers such as acrylic acid, methacrylic acid, vinylpyrroli-done, acrylamide, and 4(5)-vinylimidazole with AIBN as initiator. Complex formation between the copolymers and RNA and between the copolymers having complementary nucleic acid bases in aqueous solution and a DMSO-ethylene glycol was studied by means of UV spectroscopy. These copolymers were found to release the N-hydroxyethyl derivatives of 5-FU, thymine, or adenine by hydrolysis of the ester of the polymer side chain under mild conditions. The effects of the kind of water-soluble comonomer, temperature, pH, and the imidazole group as catalyst on the hydrolysis of the ester are discussed.     

Diameter and Refractive Index of a Cylindrical Thread Determined by Scattered Light Pattern

We have devised a method of determining the optimal value of both the refractive index n and the diameter D of a transparent cylinder by the scattering intensity pattern over a wide range of scattering angle. We have shown that the method is stable to small variations of data for the sample with D#x2272;10#x03BB; (wavelength) and could specifically determine the parameters of a spider#x0027;s thread as n = 1.520 (#x2212;0.033, #x002B;0.033), D=0.564 (#x2212;0.009, #x002B;0.011)#x03BC;m for #x03BB; = 632.8 nm.     

Spontaneous symmetry breakings in Z2 gauge theories for doped quantum dimer and eight-vertex models

Behavior of doped fermions in Z₂ gauge theories for the quantum dimer and eight-vertex models is studied. Fermions carry charge and spin degrees of freedom. In the confinement phase of the Z₂ gauge theories, these internal symmetries are spontaneously broken and a superconducting or Neél state appears. On the other hand in the deconfinement-topologically ordered state, all symmetries are respected. From the view point of the quantum dimer and eight-vertex models, this result indicates interplay of the phase structure of the doped fermions and background configuration of the dimer or the eight-vertex groundstate. At the quantum phase transitions in these systems, structure of the doped fermions groundstate and also that of the background dimer or eight-vertex groundstate both change. Translational symmetry breaking induces a superconducting or antiferromagnetic state of the doped fermions.     

Natural product-like macrocyclic N-methyl-peptide inhibitors against a ubiquitin ligase uncovered from a ribosome-expressed de novo library

Naturally occurring peptides often possess macrocyclic and N-methylated backbone. These features grant them structural rigidity, high affinity to targets, proteolytic resistance, and occasionally membrane permeability. Because such peptides are produced by either nonribosomal peptide synthetases or enzymatic posttranslational modifications, it is yet a formidable challenge in degenerating sequence or length and preparing libraries for screening bioactive molecules. Here, we report a new means of synthesizing a de novo library of “natural product-like” macrocyclic N-methyl-peptides using translation machinery under the reprogrammed genetic code, which is coupled with an in vitro display technique, referred to as RaPID (random nonstandard peptides integrated discovery) system. This system allows for rapid selection of strong binders against an arbitrarily chosen therapeutic target. Here, we have demonstrated the selection of anti-E6AP macrocyclic N-methyl-peptides, one of which strongly inhibits polyubiqutination of proteins such as p53.     

Interaction of Au(III) and Pt(IV) complex ions with Fe(II) ions as a scavenging and a reducing agent: a basic study on the recovery of Au and Pt by a chemical method

In order to develop a chemical technique for the recovery of gold (Au) and platinum (Pt) in the metallic state from spent catalysts, e.g., catalysts for environmental protection and automobile and petroleum catalysts, the coprecipitation behaviors of Au(III) and Pt(IV) complex ions with Fe(OH)(2) as a scavenging and reducing agent were investigated. The Au(III) complex ions were found to be stoichiometrically and rapidly reduced to metallic Au due to electron transfer in acidic aqueous solution prior to coprecipitation with Fe(OH)(2). Conversely, Pt(IV) complex ions were reduced only after coprecipitation with Fe(OH)(2) due to electron transfer through a Pt(IV)-O-Fe(II) bond on the solid Fe(OH)(2). Using this chemical technique, Au and Pt can be selectively and effectively recovered in the metallic state.     

Transport properties of Andreev polarons in a superconductor-semiconductor-superconductor junction with superlattice structure

Transport properties of a superconductor-semiconductor-superconductor (Su-Sm-Su) junction with superlattice structure are investigated. Differential resistance as a function of voltage shows oscillatory behavior under the irradiation of radio-frequency (rf) waves with the specific frequency of 1.77 GHz regardless of the superconducting materials and the junction geometries. Experimental data are quantitatively explained in terms of the coupling of superconducting quasiparticles with long-wavelength acoustic phonons indirectly excited by the rf waves. We propose that the strong coupling causes the formation of novel composite particles, Andreev polarons.