Search for a stochastic background of 100-MHz gravitational waves with laser interferometers

This Letter reports the results of a search for a stochastic background of gravitational waves (GW) at 100 MHz by laser interferometry. We have developed a GW detector, which is a pair of 75-cm baseline synchronous recycling (resonant recycling) interferometers. Each interferometer has a strain sensitivity of approximately 10;{-16} Hz;{-1/2} at 100 MHz. By cross-correlating the outputs of the two interferometers within 1000 seconds, we found h{100};{2}Omega_{gw}<6 x 10;{25} to be an upper limit on the energy density spectrum of the GW background in a 2-kHz bandwidth around 100 MHz, where a flat spectrum is assumed.     

Quantum molecular dynamics simulation for fragmentation of arginine molecule induced by ion impact

15 keV Ga⁺ ion impact and the thermal decomposition of arginine molecules has been simulated by quantum molecular dynamics (QMD). We obtained the calculated mass spectra which express the distribution for fragment molecule generated by ion impact or thermal decomposition. From the comparison between the experimental TOF-SIMS spectra and the calculated spectra, we discussed the fragmentation mechanism of arginine molecule by Ga⁺ ion impact.     

Molecular integrals arising in the use of the Hiller–Sucher–Feinberg–Harriman identity for describing the Fermi-contact interaction

General formulas have been derived for molecular integrals arising in the use of the identity derived by Harriman for describing the Fermi-contact interaction in a molecule. Computational aspects are discussed and numerical examples are shown for several sets of the usual Cartesian Gaussian-type orbitals.     

Broadband Antireflection Subwavelength Gratings for Polymethyl Methacrylate Fabricated with Molding Technique

We fabricated a two-dimensional subwavelength grating (SWG) on a polymethyl methacrylate (PMMA) film using a molding technique. A method of fabricating SWGs with high accuracy using a replica technique in an atmospheric environment was proposed. The SWG consisted of tapered gratings with a 200 nm period and a 200 nm deep groove. The reflectivity at wavelengths from 400 nm to 800 nm was measured and compared with the results calculated on the basis of rigorous coupled-wave analysis. At these wavelengths, the reflectivity decreased to approximately half that of the PMMA film.     

Simultaneous determination of rare earth elements by using substoichiometric separation of lanthanium

An analytical method for the simultaneous determination of rare earth elements by using substoichiometry with two chelating agents, a complexon and an extracting agent, is proposed. The principle of the method is that the element which has the lowest stability constant with the complexon is separated substoichiometrically, while other elements which have higher stability constants are separated quantitatively by a single extraction. This method was applied to neutron activation analysis of rare earth elements. Lanthanum, europium and terbium in orchard leaves were determined simultaneously by using substoichiometric separation with DTPA and TTA.     

Chromatic-distortion compensation in splitting and focusing of femtosecond pulses by use of a pair of diffractive optical elements

We propose a simple optical system to compensate for chromatic distortion that occurs during fan-out of femtosecond pulses by diffractive optics. The proposed system comprises a pair of diffractive elements, one for splitting an incoming pulse and the other for focusing the split pulses. With an appropriate separation between the elements, chromatic distortion resulting from the spectral bandwidth of a femtosecond pulse is removed, and an array of focused pulses with the same dimensions can be obtained. The theory has been verified through optical and processing experiments with 100-fs, 800-nm pulses.     

An automated fluorescence protein sequencer using 7-methylthio-4-(2,1,3-benzoxadiazolyl) isothiocyanate (MTBD-NCS) as an Edman reagent

An automated fluorescence protein sequencer using 7-methylthio-5-(2,1,3-benzoxadiazolyl) isithiocyanate (MTBD-NCS), a fluorescent Edman reagent, is developed by the modification of a commercial protein sequencer. The generated MTBD-thiohydantoin amino acids fluoresced strongly, whereas the by-products such as MTBD-thiocarbamoyl amino acids and MTBD-carbamoly amino acids did not fluoresce. A few interfering peaks were observed in the chromatogram and amino acid sequence was easily determined. The coupling and cyclization/cleavage reaction conditions and extraction conditions of generated MTBD-thiazolinone amino acids were optimized using an autonalyzer. Finally, the sequence of a synthetic peptide (25 pmol), leucine-enkephalin-Thr-amide, was determined and up to six residues were successively analyzed.