Construction of a subnanosecond time-resolved, high-resolution ultraviolet resonance Raman measurement system and its application to reveal the dynamic structures of proteins

A subnanosecond time-resolved ultraviolet (UV) resonance Raman system has been developed to study protein structural dynamics. The system is based on a 1 kHz Nd:YLF-pumped Ti:Sapphire regenerative amplifier with harmonic generation that can deliver visible (412, 440, 458, and 488 nm) and UV (206, 220, 229, and 244 nm) pulses. A subnanosecond (0.2 ns) tunable near-infrared pulse from a custom-made Ti:Sapphire oscillator is used to seed the regenerative amplifier. A narrow linewidth of the subnanosecond pulse offers the advantage of high resolution of UV resonance Raman spectra, which is critical to obtain site-specific information on protein structures. By combination with a 1 m single spectrograph equipped with a 3600 grooves/mm holographic grating and a custom-made prism prefilter, the present system achieves excellent spectral (<10 cm(-1)) and frequency (approximately 1 cm(-1)) resolutions with a relatively high temporal resolution (<0.5 ns). We also report the application of this system to two heme proteins, hemoglobin A and CooA, with the 440 nm pump and 220 nm probe wavelengths. For hemoglobin A, a structural change during the transition to the earliest intermediate upon CO photodissociation is successfully observed, specifically, nanosecond cleavage of the A-E interhelical hydrogen bonds within each subunit at Trpalpha14 and Trpbeta15 residues. For CooA, on the other hand, rapid structural distortion (<0.5 ns) by CO photodissociation and nanosecond structural relaxation following CO geminate recombination are observed through the Raman bands of Phe and Trp residues located near the heme. These results demonstrate the high potential of this instrument to detect local protein motions subsequent to photoreactions in their active sites.     

Chalcogenide coatings of Ge15Sb20S65 and Te20As30Se50

Chalcogenide coatings are investigated to obtain either optical components for spectral applications or optochemical sensors in the mid-infrared. The deposition of Ge(15)Sb(20)S(65) and Te(20)As(30)Se(50) chalcogenide glasses is performed by two physical techniques: electron-beam and pulsed-laser deposition. The quality of the film is analyzed by scanning electron microscopy, atomic force microscopy, and energy dispersive spectroscopy to characterize the morphology, topography, and chemical composition. The optical properties and optical constants are also determined. A CF(4) dry etching is performed on these films to obtain a channeled optical waveguide. For a passband filter made by electron-beam deposition, cryolite as a low-refractive-index material and chalcogenide glasses as high-refractive-index materials are used to favor a large refractive-index contrast. A shift of a centered wavelength of a photosensitive passband filter is controlled by illumination time.     

A logical basis for programming methodology

In this paper, the relation between WHILE-programs and formal proofs of their quantified specification is studied. This gives us a logical basis for programming methodology since the programming concepts such as assignment statements, IF-statements and WHILE-statements are fully explained logically, here ‘logically’ means ‘how to think’. As an example, Hoare's program FIND is studied methodologically.     

On the reaction between UO2 and Zr

The reaction between UO₂ and Zr has been studied from both equilibrium and kinetic points of view. In the equilibrium study, the reaction of UO₂ with Zr with several Zr/UO₂ mole ratios has been made at 1000°C and the products have been identified using X-ray diffraction method. The interfacial reaction zones after the heat-treatment of the reaction couples of UO₂ pellet and Zr sheet have been studied using a SEM.     

Decentralized exciter stabilizing control for multimachine power systems

In this paper, a systematic approach to design controllers based on H‐infinity theory for a multimachine power system is presented. Generally, a centralized control scheme is difficult for a large‐scale interconnected power system because of the necessity of obtaining information on the whole system, computation times, and so on. In order to handle these problems, two decentralized control schemes are proposed. One is based on the decomposition of information. The feedback gains for the whole system are obtained, and after decomposing the gains into subblocks for each area, the diagonal block is used to design the controller for each generator. The other is based on area decompositions. The procedure is carried out by decomposing the original system into blocks for each area and the local feedback gain is obtained by using information for each decomposed system. Furthermore, to improve the robustness of the system, an effective weighting matrix design, which involves the allocation of eigenvalues, is also proposed. Several simulation tests show the effectiveness of the proposed methods. © 2002 Scripta Technica, Electr Eng Jpn, 139(1): 35–43, 2002; DOI 10.1002/eej.1144     

Humidity Sensitive Electrical Conduction of ZnO-Ni1-xLixO Heterocontacts

Heterocontacts of p-n semiconductors were produced by mechanically pressing together polished surfaces of ZnO and Ni_1-xLi_xO sintered pellets. The electrical conductivity of the heterocontacts was highly sensitive to humidity. The sensitivity to changes in humidity was dependent on the surface finish of the pellets, the lithium dopant level in the NiO ceramic, and the porosity of the ZnO ceramic.     

Finding ligands for G protein-coupled receptors based on the protein-compound affinity matrix

We developed a novel method of identifying new active ligands based on information related to known active compounds using protein-compound docking simulations, even when the tertiary structure of the actual target receptor protein is unknown. This method was used to find ligands of G protein-coupled receptors (GPCRs), i.e., agonists and antagonists of histamine, adrenaline, serotonin and dopamine receptors. The principal component analysis (PCA) method was applied to the protein-compound affinity matrix, which was given by thorough docking calculations between sets of many protein pockets and chemical compounds. The set of protein pockets did not necessary include the target protein. Each compound was depicted as a point in the PCA space. Compounds in a sphere, whose center was set to the known active compound in the multi-dimensional PCA space or to the average position of several known active compounds, were selected as candidate-hit compounds. Our method was found to be effective for finding the ligands of GPCRs based on known native ligands, even when only the soluble protein structures were used in the docking simulations.     

Study of reactive diluent for air-dried alkyd paint

The conventional air-dried alkyd resin is generally used with 30% to 40% of some organic solvent which dissipates into atmosphere after painting and becomes a factor of air pollution. A reactive diluent was investigated to reduce the content of the organic solvent and to manufacture a high-solid or superhigh-solid paint. 1,1-Bis(1′-methyl-2′-vinyl-4′,6′-heptadienoxy)ethane was found to be suitable as the reactive diluent among the investigated compounds. A small addition of this compound to alkyd paint reduced the content of solvent to less than 15% with a conventional alkyd resin of high molecular weight (high-solid type); and, further, a superhigh solid paint (5% solvent) could be manufactured when this compound was added to a superlong oil-length alkyd resin of low molecular weight.