Neutron Irradiation Effects of V-Ti Binary Alloys

Mechanical Properties and microstructures of four kinds of V-Ti binary alloys were examined before and after neutron irradiation. The neutron irradiation was done in JMTR (Japan Material Testing Reactor) at an ambient temperature up to 1.5xl0^ n/m^2 (E>0.1MeV) and in RTNS-II (Rotating Target Neutron Source-II) at room temperature up to 5x10^n/m^2 (14MeV). The tensile yield strength of unirradiated V-Ti alloys increased with Ti contents, it indicated a maximum value at near V-40Ti and slightly decreased at V-60Ti. The yield strength of high Ti contents V alloys were slightly affected by neutron irradiations. JMTR irradiation gave many effects on the tensile property, while RTNS-II irradiation affected only the elongation

Trapping and detrapping of hydrogen in graphite materials exposed to hydrogen gas

Measurements of hydrogen solubility have been performed for several unirradiated and neutron-irradiated graphite (and CFC) samples at temperatures between 973 and 1323K under a ～10 kPa hydrogen atmosphere. The hydrogen dissolution process has been studied and it is discussed here. The values of hydrogen solubility vary substantially among the samples up to about a factor of 16. A strong correlation has been observed between the values of hydrogen solubility and the degrees of graphitization determined by X-ray diffraction technique. The relation can be extended even for the neutron irradiated samples. Hydrogen dissolution into graphite can be explained with the trapping of hydrogen at defect sites (e.g. dangling carbon bonds) considering an equilibrium reaction between hydrogen molecules and the trapping sites. The migration of hydrogen in graphite is speculated to result from a sequence of detrapping and retrapping events with high energy activation processes

Vibrational microspectroscopy of single proteins

Vibrational infrared absorption of a single protein molecule was detected at a few kelvins as infrared-induced recovery of visible fluorescence of a dye with which the protein was labeled. This sensitive method of detecting infrared absorption was demonstrated for a single bovine serum albumin (BSA) molecule labeled with Alexa Fluor 660 by determining the vibrational infrared absorption spectrum of the backbone vibrations of the α-helical structure in the wavelength region around 6 μm (1650 cm -1). In addition to measuring the vibrational infrared absorption spectrum, the visible fluorescence can be simultaneously used for imaging of the same dye-labeled single protein molecules

Structural change of a cofactor binding site of flavoprotein detected by single-protein fluorescence spectroscopy at 1.5 K

The visible fluorescence spectrum of single flavoprotein at a temperature of 1.5 K has been measured by one-photon excitation. The flavoprotein studied was a photoswitchable enzyme, photoactivated adenylyl cyclase. The time course of the spectrum revealed a structural change occurring at a rate of 10-3  s-1 around hydrogen bonds at the flavin cofactor binding site