Laser electron acceleration beyond 100 GeV

Nowadays there is great progress on laser-driven plasma-based accelerators by exploiting petawatt-class lasers, where for one aspect electron beams can be accelerated to multi-GeV energy in a centimeter-scale plasma due to laser wakefield acceleration mechanism. While to date, worldwide researches on laser-plasma accelerators are focused to create compact particle and radiation sources for applications in a wide range of sciences, including basic, medical and industrial sciences, there are great interests in applications for high energy physics and astrophysics that explore unprecedented high-energy frontier phenomena, for which laser plasma accelerator concepts provide us with promising tools. Here, our endeavors toward “extreme light” in the IZEST are envisaged for the next 30 years perspective and issues on laser plasma electron acceleration beyond 100 GeV and furthermore toward the TeV regime, aiming at high energy physics applications.     

Urinary metabolic profile of phenylketonuria in patients receiving total parenteral nutrition and medication

Nutrition and drugs are main environmental factors that affect metabolism. We performed metabolomics of urine from an 8‐year‐old patient (case 1) with epilepsy and an 11‐year‐old patient (case 2) with malignant lymphoma who was being treated with methotrexate. Both patients were receiving total parenteral nutrition (TPN). We used our diagnostic procedure consisting of urease pretreatment, partial adoption of stable isotope dilution, gas chromatography/mass spectrometry (GC/MS) measurement and target analysis for 200 analytes including organic acids and amino acids. Surprisingly, their metabolic profiles were identical to that of phenylketonuria. The neopterin level was markedly above normal in case 1, and both neopterin and biopterin were significantly above normal in case 2. Mutation analysis of genomic DNA from case 1 showed neither homozygosity nor heterozygosity for phenylalanine hydroxylase deficiency. The metabolic profiles of both cases were normal when they were not receiving TPN. TPN is presently prohibited for individuals who have inherited disorders that affect amino acid metabolism. Although the Phe content of the TPN was not the sole cause of the PKU profile, its effect, combined with other factors, e.g. specific medication or possibly underlying diseases, led to this metabolic abnormality. The present study suggests that GC/MS‐based metabolomics by target analysis could be important for assuring the safety of the treatments for patients receiving both TPN and methotrexate. Metabolomic profiling, both before and during TPN, is useful for determining the optimal nutritional formula not only for neonates, but also for young children who are known heterozygotes for metabolic disorders or whose status is unknown. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of supramolecular boron complex with anthryl groups exhibiting specific optical response for chloride ion

Supramolecular boron complex having plural hydrogen bonding sites and anthracene moieties was synthesized and showed an excimer emission selectively accompanied with capture of chloride ions.     

Efficient 340-nm light generation by a ridge-type waveguide in a first-order periodically poled MgO:LiNbO3

Quasi-phase-matched (QPM) UV second-harmonic generation (SHG) in a periodically poled MgO:LiNbO3 waveguide is presented. A ridge-type waveguide with high nonlinearity and strong resistance to photorefractive damage was achieved by use of an ultraprecision machining technique. By use of this waveguide in 1.4-microm periodically poled MgO:LiNbO3, a first-order QPM SHG device for 340-nm UV radiation was demonstrated. In a single-pass configuration, continuous-wave 22.4-mW UV light was generated for a fundamental power of 81 mW, corresponding to a normalized conversion efficiency of 340%/W.     

Structural kinetics studies on phase transitions of the Bi UPD layer between the (2 x 2) and (p x square root[3]) structures using surface X-ray diffraction

The kinetics of the phase transition between the (2 x 2) and (p x square root[3])-Bi structures on Au(111) was investigated using electrochemical methods and time-resolved surface X-ray diffraction. The temporal changes in the current value and the diffracted X-ray intensity that originated from the (2 x 2)-Bi overlayer were monitored during the phase transitions at various over-potentials. The phase transition models and kinetics parameters were deduced from each of the current and X-ray intensity transient curves. We also carried out comparative studies of the phase transition from the structural and electrochemical points of view. For the (p x square root[3]) --> (2 x 2) phase transition, the phase transition models determined by the X-ray and electrochemical measurements were a surface-diffusion controlled instantaneous nucleation-growth process and a Langmuir process, respectively. For the reverse transition, the phase transition models determined by X-ray and electrochemical measurements were a Langmuir adsorption process and a surface diffusion controlled nucleation-growth process, respectively. Our results revealed that the current transient curve does not always reflect the phase transition model in both cases and suggest that a structural analysis is fundamental in the phase transition studies. The disagreements between the phase transition models and their mechanisms are discussed.     

Laser fragmentation of water-suspended gold flakes via spherical submicroparticles to fine nanoparticles

By nanosecond, 532-nm laser irradiation typically at approximately 1 J/(cm2 pulse), water-suspended thin gold flakes, 0.1-0.2-microm thick but more than 10-microm across, were efficiently fragmented in a unique two-step mode, as evidenced by the in situ extinction spectra taken as a function of the laser irradiation time. The initial main photoproducts were spherical gold particles in the submicrometer regime. Their ensuing laser fragmentation in oxygen-free water environment generated stable, negatively charged, fine nanoparticles less than 10 nm in diameter, characterized by a considerably weak and blue-shifted plasmon band. The Mie theory can reproduce these distinct spectral features of the fine nanoparticles as well as the scattering-dominated extinction spectra of the submicroparticles. The submicroparticle to nanoparticle conversion seemed most likely to be a single-pulse event, not leaving any larger intermediate nanoparticles in the suspension. Oxygen, as an effective electron acceptor, strongly affected the stability of the negatively charged nanoparticles, promoting their quasi-reversible or irreversible agglomeration. From the estimated balance between the absorbed laser energy and the energies for the relevant particles to produce a high-temperature molten state, possible fragmentation mechanisms are discussed.     

Organic photoconductors. VIII. Photoconductors obtained from the reaction products of poly(9-vinyl anthracene)

9-Vinyl anthracene has been polymerized by three methods in cationic systems to obtain organic photoconductors. Cationic polymerization catalysts used were titanium tetrachloride and aluminum chloride anhydride. According to the degree of conversion from poly(9-vinyl anthracene) to poly(9,10-dimethylene anthracene) the photosensitivity increased.