Ion species discrimination method by linear energy transfer measurement in Fujifilm BAS-SR imaging plate

We have developed a novel discrimination methodology to identify ions in multispecies beams with similar charge-to-mass ratios, but different atomic numbers. After an initial separation by charge-to-mass ratios using co-linear electric and magnetic fields, individual ions can be discriminated by considering the linear energy transfer of ions irradiating a stimulable phosphor plate (Fujifilm imaging plate) by comparison with the Monte Carlo calculation. We apply the method to energetic multispecies laser-driven ion beams and use it to identify silver ions produced by the interaction between a high contrast, high intensity laser pulse; and a sub-micrometer silver foil target. We also show that this method can be used to calibrate the imaging plate for arbitrary ion species in the range of Z ≥ 6 with dE/dx > 0.1 MeV/μm without requiring individual calibration.

Effect of Small Focus on Electron Heating and Proton Acceleration in Ultrarelativistic Laser-Solid Interactions

Acceleration of particles from the interaction of ultraintense laser pulses up to 5×10^{21}  W cm^{-2} with thin foils is investigated experimentally. The electron beam parameters varied with decreasing spot size, not just laser intensity, resulting in reduced temperatures and divergence. In particular, the temperature saturated due to insufficient acceleration length in the tightly focused spot. These dependencies affected the sheath-accelerated protons, which showed poorer spot-size scaling than widely used scaling laws. It is therefore shown that maximizing laser intensity by using very small foci has reducing returns for some applications.

Characterization of micron-size hydrogen clusters using Mie scattering

Hydrogen clusters with diameters of a few micrometer range, composed of 10^8-10 hydrogen molecules, have been produced for the first time in an expansion of supercooled, high-pressure hydrogen gas into a vacuum through a conical nozzle connected to a cryogenic pulsed solenoid valve. The size distribution of the clusters has been evaluated by measuring the angular distribution of laser light scattered from the clusters. The data were analyzed based on the Mie scattering theory combined with the Tikhonov regularization method including the instrumental functions, the validity of which was assessed by performing a calibration study using a reference target consisting of standard micro-particles with two different sizes. The size distribution of the clusters was found discrete peaked at 0.33 ± 0.03, 0.65 ± 0.05, 0.81 ± 0.06, 1.40 ± 0.06 and 2.00 ± 0.13 µm in diameter. The highly reproducible and impurity-free nature of the micron-size hydrogen clusters can be a promising target for laser-driven multi-MeV proton sources with the currently available high power lasers.

Scintillator-based transverse proton beam profiler for laser-plasma ion sources

A high repetition rate scintillator-based transverse beam profile diagnostic for laser-plasma accelerated proton beams has been designed and commissioned. The proton beam profiler uses differential filtering to provide coarse energy resolution and a flexible design to allow optimisation for expected beam energy range and trade-off between spatial and energy resolution depending on the application. A plastic scintillator detector, imaged with a standard 12-bit scientific camera, allows data to be taken at a high repetition rate. An algorithm encompassing the scintillator non-linearity is described to estimate the proton spectrum at different spatial locations.

Nonlinear increase of X-ray intensities from thin foils irradiated with a 200 TW femtosecond laser

We report, for the first time, that the energy of femtosecond optical laser pulses, E, with relativistic intensities I > 10(21)  W/cm(2) is efficiently converted to X-ray radiation, which is emitted by "hot" electron component in collision-less processes and heats the solid density plasma periphery. As shown by direct high-resolution spectroscopic measurements X-ray radiation from plasma periphery exhibits unusual non-linear growth ~E(4-5) of its power. The non-linear power growth occurs far earlier than the known regime when the radiation reaction dominates particle motion (RDR). Nevertheless, the radiation is shown to dominate the kinetics of the plasma periphery, changing in this regime (now labeled RDKR) the physical picture of the laser plasma interaction. Although in the experiments reported here we demonstrated by observation of KK hollow ions that X-ray intensities in the keV range exceeds ~10(17)  W/cm(2), there is no theoretical limit of the radiation power. Therefore, such powerful X-ray sources can produce and probe exotic material states with high densities and multiple inner-shell electron excitations even for higher Z elements. Femtosecond laser-produced plasmas may thus provide unique ultra-bright X-ray sources, for future studies of matter in extreme conditions, material science studies, and radiography of biological systems.

Multi-charged heavy ion acceleration from the ultra-intense short pulse laser system interacting with the metal target

Experimental demonstration of multi-charged heavy ion acceleration from the interaction between the ultra-intense short pulse laser system and the metal target is presented. Al ions are accelerated up to 12 MeV/u (324 MeV total energy). To our knowledge, this is far the highest energy ever reported for the case of acceleration of the heavy ions produced by the <10 J laser energy of 200 TW class Ti:sapphire laser system. Adding to that, thanks to the extraordinary high intensity laser field of ∼10(21) W cm(-2), the accelerated ions are almost fully stripped, having high charge to mass ratio (Q/M).

Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser-produced plasma ions acceleration

High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams, such as high-energy proton and ions with high charge to mass ratio (Q/M; same as multi-charged ions). Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity of 1 × 10(21) W/cm(2) on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR-39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System. The results obtained provide useful approach for analyzing the various laser based ion beams.

Insertable pulse cleaning module with a saturable absorber pair and a compensating amplifier for high-intensity ultrashort-pulse lasers

We demonstrate the performance of an efficient insertable pulse cleaning module (IPCM) that uses a saturable absorber (SA) pair with a compensating multi-pass amplifier. IPCM consists of a first SA, a grating compressor, a second SA, a stretcher and a compensating Ti:sapphire amplifier. It is implemented with a conventional chirped pulse amplification (CPA) Ti:sapphire laser system, resulting in a double CPA system architecture, and suppresses the amplified spontaneous emission (ASE) level of the pulse pedestal by about three orders of magnitude while preserving the output pulse energy and repetition-rate of the overall laser system. The duration of recompressed cleaned pulses is comparable to that obtained without the cleaning module. The effectiveness of the cleaning module is confirmed in laser-driven proton acceleration experiments. At the 10(9) W/cm2 pedestal level, the surface structure and electrical resistivity of an insulator target (100 nm silicon nitride) are preserved prior to the arrival of the intense ultrashort pulse.

Mie scattering from submicron-sized CO2 clusters formed in a supersonic expansion of a gas mixture

A detailed mathematical model is presented for a submicron-sized cluster formation in a binary gas mixture flowing through a three-staged conical nozzle. By measuring the angular distribution of light scattered from the clusters, the size of CO(2) clusters, produced in a supersonic expansion of the mixture gas of CO(2)(30%)/H(2)(70%) or CO(2)(10%)/He(90%), has been evaluated using the Mie scattering method. The mean sizes of CO(2) clusters are estimated to be 0.28 ± 0.03 μm for CO(2)/H(2) and 0.26 ± 0.04 μm for CO(2)/He, respectively. In addition, total gas density profiles in radial direction of the gas jet, measuring the phase shift of the light passing through the target by utilizing an interferometer, are found to be agreed with the numerical modeling within a factor of two. The dryness (= monomer/(monomer + cluster) ratio) in the targets is found to support the numerical modeling. The apparatus developed to evaluate the cluster-gas targets proved that our mathematical model of cluster formation is reliable enough for the binary gas mixture.

Peel Adhesive Properties of Polymer Laminates Composed of Polyethylenes and Polypropylenes

Peel adhesive strengths of multi-layered laminates composed of two polypropylene (PP) sheets and an inserted polyethylene (PE) layer (the middle layer) between the PP layers were evaluated. PE-glycidyl methacrylate (GMA) copolymers and a maleic-anhydride grafted PP (MAPP) were compared to the PE homopolymer and the PP homopolymer. The peel adhesive strength of PE-GMA/MAPP laminates was much higher than that of PE homopolymer/PP homopolymer laminates. Meanwhile, the blends composed of the PE-GMA and three types of PE homopolymer (PE-GMA+LDPE, PE-GMA+MDPE, PE-GMA+HDPE) were formulated as the PE middle layer of the multi-layered laminates. The PE blends had the same amount of glycidyl groups, and the deformation capacity was different in each. Namely, the PE blend of LDPE had higher elongation to break than the PE blend of HDPE. The peel adhesive strength of the multi-layered laminates with the middle layer of the LDPE blend was highest among the three types of laminates with the middle layer of the PE blends. Scanning electron microscopy on the fractured surfaces revealed that the large plastic deformation of the LDPE blended middle layer was responsible for the high energy absorption, and resulted in the high peel strength.

Development of a single-shot-imaging thin film for an online Thomson parabola spectrometer

A single-shot-imaging thin scintillator film was developed for an online Thomson parabola (TP) spectrometer and the first analysis of laser accelerated ions, using the online TP spectrometer, was demonstrated at the JAEA-Kansai Advanced Relativistic Engineering Laser System (J-KAREN). An energy spectrum of ~4.0 MeV protons is obtained using only this imaging film without the need of a microchannel plate that is typically utilized in online ion analyses. A general-purpose Monte Carlo particle and heavy ion-transport code system, which consists of various quantum dynamics models, was used for the prediction of the luminescent properties of the scintillator. The simulation can reasonably predict not only the ion trajectories detected by the spectrometer, but also luminescence properties.

Light-Emitting Diodes Using Semiconducting Oligothiophenes

The light-emitting diodes (LEDs) using semiconducting oligothiophenes, dimethylquater-thiophene (DMQtT, tetramer), dimethylquinquethiophene (DMQqT, pentamer) and dimethyl-sexithiophene (DMSxT, hexamer), have been investigated. These oligomers were deposited on ITO-coated glass in ultra high vacuum and an aluminum electrode was subsequently vacuum-deposited on top of the oligomers. These structures have the diode configuration with Schottky barrier between the oligomers and aluminum.

The LED using DMSxT shows good rectifying feature with the rectifying ratio of 1500 at ±10V.Red-orange emission is clearly observed above 4V bias. In this LED, DMSxT acts not only as an emitting layer but also as a hole transport layer. We have also fabricated and studied alternate layered structures of DMSxT/DMQtT and DMSxT/DMQqT as the emitting layer. In these configurations, the carrier recombination can be modulated because both DMQtT and DMQqT have energy gaps wider than that of DMSxT.The quantum efficiencies (photons emitted per carriers injected) of the LEDs using DMSxT/DMQtT and DMSxT/DMQqT are about one hundred times and one thousand times larger than that of the LED solely based on DMSxT, respectively. These results indicate that the layered structures are advantageous in increasing quantum efficiency of the emission.

Energy increase in multi-MeV ion acceleration in the interaction of a short pulse laser with a cluster-gas target

An approach for accelerating ions, with the use of a cluster-gas target and an ultrashort pulse laser of 150-mJ energy and 40-fs duration, is presented. Ions with energy 10-20 MeV per nucleon having a small divergence (full angle) of 3.4 degrees are generated in the forward direction, corresponding to approximately tenfold increase in the ion energies compared to previous experiments using solid targets. It is inferred from a particle-in-cell simulation that the high energy ions are generated at the rear side of the target due to the formation of a strong dipole vortex structure in subcritical density plasmas.

Retinoic acid-inducible gene-I is induced in gingival fibroblasts by lipopolysaccharide or poly IC: possible roles in interleukin-1beta, -6 and -8 expression

Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH family of proteins, and little is known of its biological function in the oral region. We previously reported that interleukin 1beta (IL-1beta) induced RIG-I expression in gingival fibroblasts. In this study, we studied the mechanism of RIG-I expression induced by lipopolysaccharide (LPS) or double-stranded RNA (dsRNA) in gingival fibroblasts. We also addressed the role of RIG-I in the expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts stimulated with LPS or dsRNA. We stimulated cultured human gingival fibroblasts with LPS or dsRNA, and examined the expression of RIG-I mRNA and protein. The effect of cycloheximide, a protein synthesis inhibitor, on RIG-I induction by these stimuli was examined. The expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts transfected with RIG-I cDNA stimulated with LPS or dsRNA was examined. LPS or dsRNA induced the expression of mRNA and protein for RIG-I in concentration- and time-dependent manners. We also examined the localization of RIG-I, and found that it was expressed in cytoplasm. Cycloheximide did not suppress the LPS or dsRNA-induced RIG-I expression. Introduction of RIG-I cDNA into gingival fibroblasts resulted in enhanced expression of IL-1beta, IL-6 and IL-8; moreover, overexpression of RIG-I stimulated with LPS or dsRNA synergistically increased expression of IL-1beta, IL-6 and IL-8. RIG-I may have important roles in the innate immune response in the regulation of IL-1beta, IL-6 and IL-8 expression in gingival fibroblasts in response to LPS and dsRNA.

Activation of torularhodin production by Rhodotorula glutinis using weak white light irradiation

The effects of the irradiation of weak white light on the growth of the red yeast Rhodotorula glutinis and its production of carotenoids were investigated. The ability of beta-carotene and torularhodin, which are final products of carotenoid biosynthesis in R. glutinis, to quench singlet oxygen has also been investigated. Weak white light irradiation that has no effect on the growth of Saccharomyces cerevisiae inhibited the growth of R. glutinis. Simultaneously, the production of torularhodin by R. glutinis markedly increased. In a mutant of R. glutinis, which exhibited increased production of torularhodin, an increase in torularhodin production was shown as a result of light irradiation during the logarithmic growth phase. An experiment using 3-(1,4-epidioxyl-4-methyl-1,4-dehydro-1-naphtyl) propionic acid clarified that torularhodin inhibited 2,5-diphenyl-3,4-benzofran decomposition by singlet oxygen quenching more strongly than did beta-carotene. This result is consistent with the report that carotenoids having a longer polyene chain may exhibit a more potent ability to quench singlet oxygen. These results suggest that the biosynthesis of carotenoids in R. glutinis may play an important role in protecting against oxidative damage caused by light irradiation, and in particular, torularhodin which has a potent singlet oxygen quenching ability may be important. We suggest that acquisition of the ability to produce torularhodin may be an important property for this yeast to promote its wider distribution in the natural world.

Properties of a high-torularhodin-producing mutant of Rhodotorula glutinis cultivated under oxidative stress

To characterize the properties of torularhodin, which is one of the carotenoid pigments produced by the yeast Rhodotorula sp., a mutant which produces large amounts of torularhodin was constructed and its tolerance against oxidative stress was investigated. The mutant we obtained was capable of producing large amounts of torularhodin in response to irradiation with blue light. The mutant, incubated under irradiation with white light that resulted in an increased production of torularhodin, exhibited resistance to growth inhibition induced by the addition of methylene blue as the generator of singlet oxygen. Leakage of lactate dehydrogenase to the growth medium from the mutant was not increased as compared to that from a parent strain and a high-beta-carotene-producing mutant. These results suggest that an increase in the production of torularhodin reduces the susceptibility to injury induced by an active oxygen species.

Retinoic acid-inducible gene-I is induced by interleukin-1beta in cultured human gingival fibroblasts

Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH box family protein, and details of its biological function are not known. We have studied the mechanism of the interleukin-1beta (IL-1beta)-induced RIG-I expression in human gingival fibroblasts in culture. We also addressed the possibility of enhanced expression of COX-2, RANTES and galectin-9 in fibroblasts overexpressed RIG-I. We stimulated cultured human gingival fibroblasts with IL-1beta and examined the expression of RIG-I mRNA and protein by reverse transcriptase-mediated polymerase chain reaction and Western blot analysis. The effect of cycloheximide, a protein synthesis inhibitor, on the IL-1beta-induced expression of RIG-I was examined. The expression of COX-2, RANTES, galectin-9 and monocyte chemoattractant protein-1 in gingival fibroblasts transfected with RIG-I cDNA was also examined. IL-1beta stimulated the expressions of mRNA and protein for RIG-I, in cultured fibroblasts, in a time- and concentration-dependent manner. Cycloheximide did not suppress the IL-1beta-induced RIG-I expression. Introduction of RIG-I cDNA into fibroblasts resulted in enhanced expression of COX-2 mRNA, and slightly enhanced the expression of mRNA for RANTES and galectin-9. In contrast, RIG-I overexpression did not alter the level of mRNA for monocyte chemoattractant protein-1. We conclude that IL-1beta stimulates RIG-I expression in human gingival fibroblasts.

High IL-6 synthesis in cultured fibroblasts isolated from radicular cysts

OBJECTIVE

Inflammatory cytokines have been reported to be related with inflammation and expansion of jaw cysts. In this study, to examine the relationship between radicular cysts and inflammatory cytokines, it was found that there was notable unique evidence on cytokine synthesis from fibroblasts isolated from radicular cysts.

METHODS

The expression of such cytokines, namely, interleukin-1beta, IL-1beta, IL-6, IL-8, IL-10, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), transforming growth factor-beta1 (TGF-beta1), and granulocyte-macrophage colony-stimulating (GM-CSF) mRNA, in nine radicular cysts was examined and compared with that detected in six specimens of healthy gingival mucosa. Furthermore, separating all fibroblasts from their respective radicular cysts, healthy gingival mucosa, and healthy periodontal ligaments, these fibroblast groups were cultured without stimulators and a supernatant for each was obtained to analyse IL-1beta, IL-6, IL-8, TNF-alpha, and IFN-gamma by ELISA.

RESULTS

Differences between radicular cysts and healthy gingival mucosa were not clearly shown by the expression of cytokine mRNA. Analysing inflammatory cytokine synthesis in fibroblast groups from these three kinds of tissues, surprisingly, the levels of IL-6 mRNA and protein were recognised to be higher in fibroblasts of radicular cysts than in those of control tissues by ELISA and a real-time RT-PCR. Significant differences in the cultured supernatants of these fibroblast groups were not recognised in the release of IL-1beta, IL-8, TNF-alpha, and IFN-gamma by ELISA.

CONCLUSIONS

From these results, it was suggested that fibroblasts inducing IL-6 production might play important roles in the expansion of radicular cysts. It is considered that fibroblasts around radicular cysts may lead to high IL-6 synthesis over time in chronic inflammation.

Interleukin-1beta induces matrix metalloproteinase-1 expression in cultured human gingival fibroblasts: role of cyclooxygenase-2 and prostaglandin E2

OBJECTIVE

Matrix metalloproteinases (MMPs) degrade extracellular matrices and are responsible for excessive connective tissue breakdown in inflammatory disorders. We investigated the mechanism of MMP-1 expression in human gingival fibroblasts in response to the stimulation with interleukin-1beta (IL-1beta), and the role of inducible-type cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in the regulation of MMP-1 expression.

MATERIALS AND METHODS

We stimulated cultured human gingival fibroblasts with r(h)IL-1beta, and examined the expression of MMP-1 mRNA and protein by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. The effect of indomethacin, dexamethasone, or cycloheximide (CHX) on the IL-1beta-induced expression of MMP-1 was examined. The expression of MMP-1 in gingival fibroblasts stimulated with PGE2 was also examined.

RESULTS

IL-1beta stimulated the expressions of mRNA and protein for MMP-1, in cultured fibroblasts, in time- and concentration-dependent manners. Pretreatment of the cells with indomethacin or dexamethasone inhibited the IL-1beta-induced MMP-1 expression. CHX, a protein synthesis inhibitor, also suppressed the MMP-1 expression. IL-1beta also induced COX-2 expression in gingival fibroblasts, and PGE2, a major COX-2 product, was found to enhance MMP-1 expression.

CONCLUSION

The IL-1beta-induced MMP-1 expression in gingival fibroblasts may be mediated, at least in part, by COX-2 and its product PGE2.

Spontaneous bubble domain formation in a layered ferromagnetic crystal

Magnetic domain structure on the surface of the layer-structured ferromagnet La1.4Sr1.6Mn2O7 was observed in the temperature range from 37 to 97 kelvin with a scanning Hall probe microscope. The sensitivity to temperature of the domain structure changes was large relative to that in conventional ferromagnets. The stable and spontaneous appearance of magnetic bubble domains without an external magnetic field was observed in the neighborhood of 70 kelvin. The phenomenon observed could provide a potential route toward magnetic bubble memory.

New method of Helmholtz coil alignment

A new alignment method for Helmholtz coils is proposed. This method is based on a probe, whose axis is the same as the alignment axis. This probe includes one magnetic sensor, whose position is slightly shifted from the probe axis, and which is set perpendicular to the axis. Using this probe, the tilt and shift of the magnetic centre of Helmholtz coils can be aligned to within an order of 0.1 mrad and 0.1 mm, respectively. Moreover, by this method, effects of terrestrial magnetism and tilt of the magnetic sensor can be removed from the measurement. This alignment method is presented along with an estimate of the alignment accuracy of the SPring-8 linac injector.

A solid-state ambulatory physical activity monitor and its application to measuring daily activity of the elderly

An ambulatory acceleration monitor was developed and used to evaluate physical activity in the elderly. The ECG and accelerations at the wrist, waist, and ankle were recorded, and the heart rate and frequency and amplitude of accelerations per unit time were evaluated in both working and retired elderly women performing normal daily activities. The heart rate closely paralleled wrist acceleration. The behaviour patterns of the subjects could be differentiated by time interval signals and histogram distributions. This system appears to be an effective method of understanding and describing the characteristic activities of the elderly in a quantitative and objective fashion.