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Abstract One of the important requirements of foundation rock mass under dam is resistance to leakage of water. The mechanism of water leakage depends on the hydraulic properties of rock mass. When considering water leakage in fracture-dominant rock mass, the pathway of the flow is controlled by distributions and connectivity of permeable fractures. In such case, a use of discrete fracture network (DFN) models is effective to simulate the groundwater flow, as DFN approach can express fractures stochastically in three-dimension based on statistical distribution of fracture parameters. One of the key challenges when building a DFN model for dam foundation rock mass is hydraulic characterization of fractures. Hydraulic characterization in this context refers to the process of assigning hydraulic properties to the fractures generated from the geometric information. In this paper, an approach to construct a DFN model for dam foundation rock mass is proposed, with a focus on hydraulic characterization of fractures, along with a case study of foundation rock mass of an embankment dam in Japan to demonstrate the application of proposed approach.

We have investigated key factors for controlling the polytype and surface morphology of 4H-SiC homoepitaxial growth on less than 4o off-axis substrates. In addition, we characterized the crystal quality and surface quality of the epitaxial layer in whole 3-inch vicinal off angled substrate. The results suggested that the control of surface energy, control of the vicinal off angle itself, and high temperature growth, is highly important in controlling the surface morphology and polytype stability of the epitaxial layer grown on a vicinal off angled substrate. We also obtained a high-quality epitaxial layer grown on a 3-inch vicinal off angle substrate, which was comparable to those on 4o off-axis substrates. These results suggest that the wafer off angle for epitaxial growth can be reduced to less than 4 degrees.

Non-polar GaN substrates have attracted attention because they can improve the performance of GaN devices. Growth of high-quality non-polar GaN single crystals, however, has not been realized. Here, we attempted to grow m-plane GaN crystals using the Na flux method and investigated the effect of additives such as Ca and Li in Na flux on transparency, surface roughness, and crystallinity. We found that the addition of Ca and Li improved the transparency and the surface roughness of the crystals. Moreover, high-temperature growth improved crystallinity and decreased impurities such as Ca, Li, and O in GaN crystals. We also found that the crystallinity did not depend on the concentrations of impurities in GaN crystals. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Short-lived radionuclides for positron emission tomography (PET) examinations in medicine are produced mainly using on site small cyclotrons. The operation of the cyclotron generates a significant quantity of neutrons, which will activate the cyclotron and surrounding materials. A new technique is proposed to estimate the neutron fluxes in the cyclotron rooms, in which small bolts in the cyclotron rooms were used as surrogates for neutron detectors. The measurements were carried out at four PET cyclotrons. The induced radioactivity of the bolts was analyzed by gamma-ray spectroscopy and elemental analysis. A gold foil activation method was applied to compare the results. The neutron fluxes in the PET cyclotron rooms were in the range of 105∼106 cm−2 s−1 during 18F production. In the brass bolts, 69mZn, 65Zn, 64Cu, 58Co, and 60Co were detected. In the iron bolts, 56Mn, 54Mn, 59Fe, 60Co, 69mZn, and 65Zn were detected. In the stainless steel bolts, 58Co, 60Co, 56Mn, 54Mn, and 59Fe were detected. Neutron fluxes estimated from the activities of 56Mn agreed well with those by the Au foil method. The feasibility of estimating the neutron fluxes in cyclotron rooms by means of radioactive analysis of bolts in the rooms was proven.

Highly selective and sensitive γ-ray detection was performed by coincidence and anticoincidence event analysis after list-mode data acquisition using an HPGe spectrometer equipped with NaI(Tl) and plastic scintillation detectors. In order to obtain the most suitable detection of specific nuclides, coincidence or anticoincidence spectra could be freely constructed by extracting events with particular time and energy correlations. Although the detector arrangement of this system was the same as that of a typical Compton suppression spectrometer, background counts were drastically reduced and γ-rays of particular nuclides could be selectively detected by using γ-γ, γ-X, γ-X-X, and γ-β+ coincidences.

Activation is one of the severe problems at the high-energy accelerator facilities. By using gamma-ray spectrometry and activation detector technique, we could obtain important information on (1) nuclear reactions, (2) energy spectra of secondary particles, (3) penetration behavior of secondary particles in shield wall, (4) historical record of beam loss occurred in the accelerator rooms. It was concluded that the technique and knowledge of activation analysis are very useful to solve the radiation protection problems at the accelerator facilities.

For evaluation of radioactivity induced in the concrete samples from accelerator facilities, the residual radioactivity in concrete sample, collected from seven accelerator facilities, was determined by γ-ray spectrometry. The tritium was extracted by the heating method using an IR furnace, and measured with a liquid scintillation counter. It was found that the major radioisotopes activated mainly by neutrons in the concrete samples were 152Eu, 60Co, 134Cs and 3H. The concentrations of radioactivities induced by thermal neutron capture are the highest at a depth of 10 cm in the concrete wall. The correlation between tritium, 60Co and 152Eu activity was investigated by measuring many concrete samples for seven accelerator facilities. The results indicate that their activities are strongly correlated with each other. So it would also be concluded that the total activity in shielding concrete could be estimated on the basis of the activities of 60Co and 152Eu.

In order to estimate the total radioactivity induced in a concrete shield by thermal neutron-capture reactions at high-energy accelerator facilities, the observed activity of 36Cl in the concrete is expected to serve as an indicator of the thermal neutron fluence. Since 36Cl can also be produced from K and Ca by spallation reactions, we measured these production rates in order to clarify the contribution of each reaction. The Cl, K, and Ca targets were irradiated with neutrons having a maximum energy of 500 MeV. As a result, the production rates of 36Cl from Cl were only two orders higher than those from K and Ca. It was found that the 36Cl production ratios from Cl, K, and Ca were 6.7%, 6.8%, and 86.5%, respectively, and Ca was the main source of 36Cl production.

The thermal neutron fluence that poured into the shielding concrete of proton accelerator facilities was estimated from the in situ production of 36Cl. The thermal neutron fluences at concrete surfaces during 10–30 years of operation were in the range of 1012–1014 n/cm2. The maxima in thermal neutron fluences were observed at ≈5–15 cm in the depths analyzed for 36Cl/35Cl by AMS. These characteristics imply that thermalization of neutrons occurred inside the concrete. Compared to the several tens of MeV cyclotrons, secondary neutrons penetrate deeper into the concrete at the high-energy accelerators possessing acceleration energies of 400 MeV and 12 GeV. The attenuation length of neutrons reflects the energy spectra of secondary neutrons emitted by the nuclear reaction at the beam-loss points. Increasing the energy of secondary neutrons shifts the maximum in the thermal neutron fluences to deeper positions. The data obtained in this study will be useful for the radioactive waste management at accelerator facilities.

We measured the production rates of the spallation of 197Au, of which plates were attached on the wall of the neutrino target station of KEK, induced by the secondary particles emitted from the 12-GeV proton bombardment of a thick aluminum target. The spallation production rates of 197Au were also calculated using the newly issued MARS15 code system in order to compare the experimental and theoretical production rates. The calculated production rates agreed with the experimental ones. Products with mass numbers close to that of 197Au were produced by the prominent low-energy neutrons. Although, at energies higher than 300 MeV, the fluxes among neutrons, protons, π+ and π− were comparable, the pionic nuclear reactions were highly effective in producing lighter-mass products (

Excavation and re-distribution of the stress around the tunnel lead to the development of an excavation damage zone (EDZ). While the bulkheads are keyed into the rock wall of the tunnel to act as cut-offs for the EDZ of the tunnel, clay grouting was conducted around the clay bulkhead as an additional measure to interrupt the connectivity of EDZ at the bulkhead. Clay grouting is being tested to determine if it is an effective method to reduce the permeability of fractured rock. The grouting into the EDZ is difficult because many of the fractures in the EDZ are connected with the excavation surface and cannot be filled efficiently by pressurizing the grout slurry. Therefore, the in situ injection tests of the clay grouting technique for the EDZ adjacent to the clay bulkhead were conducted to demonstrate the clay grouting technique and to estimate the ability of clay grouting to reduce permeability in the EDZ. This paper presents the results of these tests. Three in situ tests of clay grouting were performed during the Tunnel Sealing Experiment (TSX), conducted at Canada’s Underground Research Laboratory (URL) in the granitic rock to demonstrate technologies for tunnel sealing at full-scale. First, a clay grouting trial was conducted at a trial key in the tunnel about 25 m above the TSX tunnel. Secondly, the two series of clay grouting were performed in the TSX tunnel, on the upstream face of the key prior to the installation of the seal material of the clay key and later on the downstream side of the bulkhead. The results of these tests indicated a reduction in the permeability of granitic rock around the holes after grouting.

The Tunnel Sealing Experiment (TSX), a major international experiment, demonstrating technologies for tunnel sealing at in situ full-scale, was conducted at Atomic Energy of Canada Limited’s Underground Research Laboratory (URL). The objective of the experiment was to demonstrate technologies for construction of bentonite and concrete bulkheads, to quantify the performance of each bulkhead and to document the factors that affect the performance. It was not the purpose of the experiment to demonstrate an optimized bulkhead. Two bulkheads, one composed of low-heat high-performance concrete and the other of highly compacted sand-bentonite material, were constructed in a tunnel in unfractured granitic rock at the URL. The chamber between the two bulkheads was pressurized with water to 4 MPa in a series of steps over a two-year period. The ultimate pressure is representative of the ambient pore pressures in the rock at a depth of 420 m. The first phase of the TSX was conducted at ambient temperature (15 °C) while a second phase involved heating the pressurized water between the bulkheads with temperatures ultimately reaching 65 °C near the upstream face of both bulkheads. Instrumentation in the experiment monitored parameters that are important indicators for bulkhead performance. Seepage was measured at both bulkheads and any other leakage points from the tunnel to maintain a water balance. At 4 MPa pressure in the tunnel and ambient temperature the clay and concrete bulkheads had seepage rates of 1 mL/min and 10 mL/min respectively. Heating caused the concrete bulkhead to expand by a maximum of 0.2 mm, further reducing seepage to 2 mL/min. Heating did not affect the seepage rate at the clay bulkhead. The paper provides an overview of the project.

A major international experiment, demonstrating technologies for use in sealing the rooms and tunnels of a nuclear waste repository was conducted at Canada’s Underground Research Laboratory between 1998 and 2004. Two bulkheads separated by 12 m were installed in a 3.5-m-high by 4.25-m-wide tunnel located 420 m below the surface in an intact volume of rock within a granitic pluton. These bulkheads isolated a section of tunnel that was subsequently flooded, stepwise pressurized to 4 MPa and then following extended operation at ambient temperature the water in the flooded tunnel was heated. Heating occurred for a period of approximately one year prior to decommissioning of the TSX. One bulkhead consisted of high-performance concrete and the other of blocks of compacted sand-bentonite material. The performance of these two bulkheads was monitored throughout the experiment in order to evaluate the influence of elevated hydraulic head and tunnel temperature on these materials. This paper provides a brief overview of the evolution of the clay bulkhead portion of the TSX and generally discusses the water uptake, physical deformation and stresses developed and monitored in the course of TSX operation. At the end of 5 years of operation the TSX was dismantled and extensively sampled allowing for development of detailed density and water content profiles for the clay bulkhead. This also allowed the instrument responses to be compared to the physical state at the time of decommissioning. The majority of the very limited seepage past the clay bulkhead occurred at the outer perimeter regions of the clay bulkhead and that this was the region that will require particular attention when it comes time to construct bulkheads in an actual repository. Continual swelling at the upstream face of the bentonite-based clay bulkhead as downstream compression occurred meant that a positive contact was maintained between the clay bulkhead and the surrounding rock and other confining media. It also provided an excellent demonstration of the self-sealing capacity of bentonite-based materials.

Effects of Si addition on microstructure, transformation temperature and mechanical properties of a Ni-free biomedical superelastic β-Ti alloy, Ti–24 at.%Nb–3 at.%Al (TiNbAl), were examined in the compositional range from 0 to 0.9 at.%Si. After the solution treatment at 1273 K, the constituent phases of the alloys with Si concentration lower than 0.7 at.% are parent β-phase (bcc) and athermal ω-phase. The alloys with Si concentration higher than 0.7 at.% contains incoherent (Ti, Nb) 3 Si particles. Then, the solid solubility limit of Si in TiNbAl at 1273 K is estimated to be 0.7 at.%Si. Tensile tests revealed that the stress for inducing martensite is raised by Si addition. Thermomechanical analysis revealed that the reverse martensitic transformation finish temperature ( A f ) becomes lower by Si addition by −250 K/at.%Si. The critical stress for slip deformation evaluated using residual strain increases with increasing Si concentration up to 0.7 at.%Si and the hardening rate is estimated to be 300 MPa/at.%Si. This hardening caused by Si addition is due to the solid-solution strengthening. When Si concentration exceeds 0.7 at.%, incoherent Ti 3 Si-type precipitates are formed during the homogenization at 1273 K, and no further hardening occurs. Consequently, apparent transformation strain drastically decreases when Si concentration is higher than 0.7 at.%. The Ti 3 Si-type particles are suggested to act as an obstacle for the stress-induced martensitic transformation. It was concluded that Si is effective to reduce M s and to raise critical stress for slip of TiNbAl, and that the formation of Ti 3 Si-type precipitates exhibits negative effect for superelasticity.

Standards for the measurement procedures of nitrogen concentration in CZ silicon crystals were established for infrared absorption spectroscopy (IR), secondary ion mass spectroscopy (SIMS) and charged particle activation analysis (CPAA) for concentration above 1x1014 atoms/cm3.Good agreement was obtained between the laboratory within the same method and between the three methods. Conversion coefficient from (weighted sum of) absorption coefficients to nitrogen concentration agreed well with the previous one.

We have studied the photon activation analysis of carbon in InF3-based fluoride, chalcogenide and tellurite glasses for fiber amplifiers, and especially the nuclear interference from a matrix produced by (γ,n), (γ,2n), (γ,p) and (n,γ) reactions and a flow method for the rapid and simple separation of 11C. A chemical separation technique is indispensable for determining carbon, because seventeen radionuclides are observed in these glasses. The flow method can sequentially be undertaken, the fusion of an irradiated sample with an oxidizer, the conversion of 11C into 11CO2, and the absorption of 11C in ethanolamine solution. We used a mixture of Pb3O4 and B2O3 as the oxidizer. There is interference with the 11C measurement because 18F and 68Ga are produced in fluoride and chalcogenide glasses by the 19F(γ,n), 23Na(γ,αn) and 69Ga(γ,n) reactions, respectively, and also absorbed in ethanolamine solution. Therefore, this flow method can only be applied to tellurite glasses. The chemical yield provided by the flow method was close to 100% when determining carbon in Japanese Iron and Steel Certified Reference Materials (JSS) by using lithium carbonate as a standard sample. We determined that the carbon concentrations in four kinds of tellurite glass were 7 to 14 ppm.

An infrared furnace (ULVAC RHL-410P) was newly applied to the extraction of tritium from concrete samples. After studying the tritium recovery yield regarding temperature and time, the best extraction conditions were set to 800 °C (setting temperature) for 30 minutes under Ar-gas flow of 200 ml/min. Tritium was collected in two cold traps and transferred to a vial for liquid scintillation counting. It took about one hour for the extraction of tritium. Reproducibility and recovery yield of tritium were about 100% compared to the values obtained by the ordinary heating method using an electric furnace. Gamma-ray emitters and tritium of concrete samples collected from several accelerator facilities have been determined. The specific activity of tritium strongly correlated with that of 152Eu and 60Co, so it was found that tritium was produced by thermal neutron reaction by the 6Li(n,α)3H reaction. The results indicate that the tritium specific activity in concrete can be estimated from the 60Co specific activity obtained easily by γ-ray measurement.

Inverse modeling by the pressure derivative matching method for two-phase fluid flow was developed and applied to construct the heterogeneous permeability distribution of a vertical sandstone plate using air injection test data under unsaturated conditions. To reduce the computing effort, the adjoint state method was used to calculate gradients of the extended objective function which includes the squared sum of differences between calculated pressure change rate and observed one. The method can also treat capillary pressure. The quasi-Newton method was used as an optimization algorithm. Laboratory tests were carried out to obtain transient pressure data at multiple points in the unsaturated zone of the sandstone.We compared the pressure derivative matching method with a conventional matching method. The results show that the pressure derivative matching method is effective for transient pressure data obtained by the laboratory test.

We have investigated the optical and electrical properties of Bi- or Tl-doped Pb 1− x (Mg 1− y Sr y ) x S thin films. The films with carrier concentration sufficient for use as cladding layers in a laser diode, were obtained by doping with Bi as n-type impurity or Tl as p-type impurity. Optical absorption was observed at far-infrared region on the Bi-doped films, and the relation between absorption coefficient α and carrier concentration n was found to be expressed as α =0.27 n 0.21 at 6 μm.

We demonstrate electro-optic spectral tuning in a pulsed periodically poled LiNbO3 (PPLN) optical parametric oscillator (OPO) in ns regime. A 3-cm-long LiNbO3 crystal is segmented in three equal sections; the outer sections are periodically poled. The center segment is of single domain whose refractive index is changed by electro-optic effect. Applying voltage from 0 to −5000 V, the OPO signal and idler waves are tuned from 1.932 to 1.912 μm and 2.368 to 2.40 μm, respectively. The signal and idler waves obtained are difference-frequency-mixed in a 10 mm long AgGaS2 crystal to produce mid-IR tunable from ∼10.5 to ∼9.4 μm, which matches the tuning range of a CO2 laser.

We report a temperature tuned mid-IR generating system ranging from 5 to 12 μm by difference frequency mixing of output waves from two optical parametric oscillators (OPOs) in a silver gallium sulfide (AgGaS2) crystal. One of the OPOs generate signal wave of 1.6 μm, while the other produced tunable radiation from 1.846 to 2.353 μm. The AgGaS2 crystal is temperature tuned to allow phasematching for tunable output from 5 to 12 μm.

We have investigated the fabrication of the PbS single crystal with well-developed facet under the vapor pressure of sulfur. The relation between the vapor pressure of sulfur pS and the growth temperature Tg followed the expression as log(pS)=38−37410 Tg−1, when the faceted PbS single crystal was obtained. The conductivity type of the crystals changed from n-type to p-type in the vicinity of 100 Pa for pS, and the carrier concentration varied from 1016 to 1018 cm−3 at 77 K with respect to pS. This means that the deviation from stoichiometry in the faceted PbS single crystal can be controlled by pS. The flat surface thus obtained in the as-grown (1 0 0) facet allows us to use as a substrate directly for the mid-infrared laser without any mechanical polishing and chemical etching.

We have investigated new quaternary solid solution semiconductor Pb 1− x (Mg 1− y Sr y ) x S ( x 2 (1 1 1) substrate by using hot-wall epitaxy. It has been found that the energy band gap can be controlled desirably under keeping the lattice constant and monitoring the growth conditions. The properties of the optical absorption edge observed are suggestive of a direct energy band gap structure. The Hall mobility for the films changes monotonically from 4423 to 337 cm 2 /V s at 77 K with increasing x . The full-width at half-maximum of the films lattice-matched to PbS increases from 133 to 208 arcsec in proportion to x under the lattice misfit of 4.3% between the film and the BaF 2 .

High quality ZnTe epilayers on (1 0 0) GaAs substrates have been successfully grown by hot wall epitaxy. The strain in the hetero-interface has been studied by four-crystal X-ray diffraction and transmission electron microscopy (TEM). The smallest FWHM value of the four-crystal X-ray rocking curve was 66 arcsec, which is the best so far value reported. On the other hand, the reciprocal lattice mapping indicates a splitting of the (4 0 0) peaks from the GaAs substrate, indicating the existence of a strained region in the substrate. A TEM study confirms that the strain exists not only in the ZnTe epilayers but also in the GaAs substrate near the interface. This is the first such direct observation for the case of ZnTe/GaAs.

The proton activation analysis of oxygen was studied in fluoride and chalcogenide glasses used for fiber amplifiers. First, we studied the interfering nuclear reactions from glass matrices to determine the oxygen concentration in these glasses. By using substoichiometric separation for 18F after irradiation, we found that the oxygen concentration was 12 to 204 ppm in InF3-based fluoride glass and 0.04% to 0.7% in chalcogenide glass containing sodium. We also discuss the relation between oxygen concentration and optical properties such as the infrared absorption spectrum and fluorescence lifetime.

The behavior of radionuclides in the cooling water for the electromagnets at the 12 GeV proton accelerator facility was studied by measuring γ-ray spectra of the cooling water and the ion-exchange unit in the water circulation system. These measurements indicated that the major photon radiations originating from the cooling-water were annihilation radiation from the positron emitters 11C, 13N and 15O during the accelerator’s operation, while γ-ray emission from 7Be became dominant several hours after the beam operation had stopped. Spatial distribution and behavior of 11C and 7Be in the cooling-water system were discussed based on their existing states in water.

We have investigated the fabrication of Pb 1− x Mg x S thin films on BaF 2 substrates by using hot-wall epitaxy. Mg concentration x and its deviations from stoichiometry in the Pb 1 −x Mg x S thin films were controlled by monitoring the growth conditions. We found a widened solubility range of Mg in the Pb 1 −x Mg x S thin film as compared to the same range obtained for bulk growth. The values of the energy band gap of the films increased with increasing x . The relation between the energy band gap E g and the composition x of the Pb 1 −x Mg x S thin films follows the expression E g =0.417+1.111 x −0.861 x 2 ( x ⩽0.12). The information obtained here will be useful for future preparation of Pb 1− x Mg x S 1− y Se y or Pb 1− x (Mg 1− y Sr y ) x S quaternary films for fabrication of mid-infrared lasers.

We have investigated a new semiconducting material Pb1−x(Mg1−ySry)xS, a quaternary solid solution compound. The experimental results obtained on bulk samples heat-treated under thermal equilibrium show that the lattice constants and the energy band gaps at room temperature of the Pb1−x(Mg1−ySry)xS system change from 5.862 to 6.120 A and from 0.41 to around 0.9 eV, respectively, with changes of x. This suggests that the Pb1−x(Mg1−ySry)xS compounds have a potential for wide wavelength coverage from mid-infrared to near infrared if the quaternary solid solution semiconductor is used as the active layer in a laser diode. The solubility limit of x in the Pb1−x(Mg1−ySry)xS system along the line of lattice-matching to a PbS is 0.17 at 1000°C, and the difference in the energy band gap between the Pb1−x(Mg1−ySry)xS and the PbS is 0.46 eV in maximum at room temperature.

Polymer-dispersed liquid crystals (PDLCs) with macroscopically uniaxial molecular alignment containing azobenzene molecules were prepared. The PDLCs were transparent because of their macroscopically uniaxial molecular alignment. Upon photoirradiation to cause trans–cis photoisomerization of azobenzene molecules, the PDLCs became translucent. The PDLC systems do not require the use of polarizers and electrodes to fabricate optical devices. The light scattering is attributed to a bi-phasic morphology in the systems produced transiently by means of a partial photochemical phase transition. The light-scattering behavior was investigated with respect to the effect of the polymer segments in the PDLCs. Copyright © 2000 John Wiley & Sons, Ltd.

We have investigated Pb 1− x Ca x S 1− y Se y solid solution semiconductor. Results obtained on bulk thermal equilibrium heat-treated samples show that the lattice constants and the energy band gaps at room temperature of the Pb 1− x Ca x S 1− y Se y system change, respectively, from 5.862 to 6.120 A and 0.286 to around 0.9 eV. Namely, the variation of the energy band gap suggests that the Pb 1− x Ca x S 1− y Se y system covers a wide wavelength range from mid-infrared to near infrared if this quaternary solid solution is used as the active layer in a laser diode. From the results obtained by high-resolution X-ray diffraction with a four-crystal monochromator, no rhombohedral distortion is formed in Pb 1− x Ca x S thin films employing BaF 2 (1 1 1) substrate and that the quality of these films is limited by mosaicity rather than slight variations of the lattice constant.

We studied the production of nine typical organic analytical reagents labeled with11C,13N and18F by irradiation with charged particles and bremsstrahlung and the purification of labeled compounds with HPLC and sublimation. As a result, we found that six reagents, α-naphthol, β-naphthol, quinoline, α-nitroso-β-naphthol, 8-hydroxyquinoline, and 1,10-phenanthroline H2O could be labeled with11C by bombarding a mixture of each reagent and boron with protons. More than 10% of the11C was successfully exchanged with carbon atoms in the original reagents. We also found that sublimation is useful for purifying 8-hydroxyquinoline labeled with11C. The extraction property of11C-labeled 8-hydroxyquinoline between water and chloroform could be easily monitored by radioactivity measurement.

The effect of following interferences was quantitatively assessed in terms of interference factor by irradiating samples together with highly pure reagents at two reactor sites of diferent neutron spectra and fluxes for neutron activation analysis (NAA) and an electron LINAC for photon activation analysis (PAA). The interfering reactions studied are 91) fast neutron-induced reactions, (2) uranium fission (3) (n,γ) reactions of other target elements in NAA, and (4) reactions induced by secondary neutrons in PAA. Corrections for these interferences were successfully applied to the activation analysis of some geological reference rock samples and biological samples.

Iodine, thallium and uranium were determined by photon activation analysis. Two electron linear accelerators were used for the analysis of several kinds of environmental, biological and geochemical reference materials under different irradiation conditions. Both analytical results for iodine were in good agreement with each other but not with literature values in the case of environmental samples. The results of thallium and uranium agreed well with their reference values. The detectable concentration levels of iodine, thallium and uranium were almost 0.3μg/g.

Fullerenes, C60 and C70, were irradiated by 8 and 10 MeV deuterons. The irradiated samples were dissolved in CS2 and filtered to remove insoluble by-products. Finally, radioactive fullerenes and products, such as fullerene dimers, trimers labeled with13N, were isolated and detected in the liquid phase by radiochromatography. This suggests that the energy rich13N atoms successfully incorporated into the fullerene cages and that the disrupted cages reacted with neighboring cages.

C60 and C70 fullerenes were irradiated by high-energy γ-rays and charged particles. Coalesced products of C60 and C70 have been isolated and detected in the liquid phase by a radiochromatographic technique. It was found that not only 11 C radioactive fullerene dimer, trimer, and possibly tetramer were produced by a recoil implantation process following nuclear reaction, but also such non-radioactive coalesced products were produced by the recombination process after ionization by γ-rays or charged particles.

The C60 and C70 fullerenes were irradiated by high-energy gamma-rays and charged particles. The irradiated samples were dissolved in CS2 and/or toluene and filtered to remove insoluble by-products. Finally, radioactive fullerenes and products labeled with 11C or 13N were isolated and detected in the liquid phase by radiochromatography. It was found that (1) not only 11C or 13N radioactive monomer fullerenes but also their dimers (trimers and, possibly, tetramers) were produced by recoil implantation process following nuclear reaction and (2) the radioactive fullerene labeled with 11C yields has led to high yields.

The11C and14C labeled fullerenes were produced by charged-particle and neutron irradiation, of C60, C70 and their mixture. It was found that a carbon atom of fullerence can be easily exchanged with a radioactive carbon atom produced by a nuclear reaction. The HPLC method was effective for identification and purification of various labeled fullerene families as chemically stable compounds. The radiochemically interesting aspect of the results is not only the production of11C and14C labeled fullerenes but also the formation of radioactive higher fullerenes which can be simultaneously produced with high yield and in carrier-free form.

Recently, efficiency improvement has been noted with the rapidly increasing consumption of energy. The diode loss in bridge rectifier is the main cause of efficiency decrease in conventional PFC circuit, it can not be neglected. Therefore bridgeless PFC circuit has been focused. In this research, the various bridgeless PFC circuits are analyzed. The results of switching noise are compared and efficiency improvement is verified.

The permeability, temperature and morphologic changes of the wall of the root canal induced by Nd:YAG, CO2 and argon lasers were studied. The changes were evaluated according to the presence or absence of a smear layer. Root canals of 140 human single-rooted teeth were enlarged using a step-back technique. Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. Temperature changes were measured using a thermovision system, and morphological changes were evaluated by scanning electron microscopy. Laser energy was delivered into the canal by means of a flexible optical fibre or metal tip. There were statistically significant differences in permeability between lased groups with and without a smear layer in the cervical third of the root canal following lasing. In the middle third of the root canal, all three laser types induced permeability increases in groups with a smear layer. In the apical third, statistically significantly decreases in permeability were observed among CO2 laser and Nd:YAG compared with control group (P < 0.01). Rises in temperature ranged from a minimum of +10.1 degrees C (CO2 laser) to a maximum of +54.8 degrees C (argon laser). All three laser devices appeared capable of producing a glazed-like surface and craters.

A dedicated NAA calibration method was developed for the determination of the neutron spectrum monitor elements Co, Au and Lu in alloyed wires and foils, with an accuracy of better than 1%. The method does not require quantitative micropipetting for preparing the standards, and leads to vanishing errors caused by flux inhomogeneities and by differences in counting geometry and gamma attenuation. Its performance was tested by analysing various NIST, IRMM and RX aluminium-based materials with certified or specified Co, Au or Lu content.

Kallmann syndrome is a form of hypogonadotropic hypogonadism also associated with the loss of smell. It is a phenotypically and genetically heterogeneous disorder, with mutations in several known causative genes now accounting for approximately 30% of cases. The prevalence for the disease is also much higher in males than in females, a phenomenon that remains to be fully explained. Here, we show that loss of Prokr2, which is linked to autosomal recessive Kallmann syndrome type 3 (KAL3; OMIM 244200), affects fetal testis differentiation in mice. We find that Prokr2 is specifically expressed in the XY gonads during sex determination and fetal sexual differentiation, and knockout mice display a variable degree of compromised vasculature in the fetal testes. This phenotype offers potential insight into the clinical heterogeneity observed within familial cases, and may contribute to the gender bias in Kallmann syndrome patients.

To document outcome and to explore prognostic factors in fetal left congenital diaphragmatic hernia (CDH).This was a multicenter retrospective study of 109 patients with prenatally diagnosed isolated left CDH born between 2002 and 2007. The primary outcome was intact discharge, defined as discharge from hospital without major morbidities, such as a need for respiratory support including oxygen supplementation, tube feeding, parenteral nutrition or vasodilators. All patients were managed at perinatal centers with immediate resuscitation, gentle ventilation (mostly with high-frequency oscillatory ventilation) and surgery after stabilization. Prenatal data collected included liver and stomach position, lung-to-head ratio, gestational age at diagnosis and presence or absence of polyhydramnios. Stomach position was classified into four grades: Grade 0, abdominal; Grade 1, left thoracic; Grade 2, less than half of the stomach herniated into the right chest; and Grade 3, more than half of the stomach herniated into the right chest.Overall intact discharge and 90-day survival rates were 65.1% and 79.8%, respectively. Stomach herniation was classified as Grade 0 in 19.3% of cases, Grade 1 in 45.9%, Grade 2 in 13.8% and Grade 3 in 21.1%. Multivariate analysis revealed that liver position was the strongest prognostic variable for intact discharge, followed by stomach position. Based on our results, we divided patients into three groups according to liver (up vs. down) and stomach (Grade 0-2 vs. Grade 3) position. Intact discharge rates declined significantly from liver-down (Group I), to liver-up with stomach Grade 0-2 (Group II), to liver-up with stomach Grade 3 (Group III) (87.0%, 47.4% and 9.5% of cases, respectively).Current status and outcomes of prenatally diagnosed left CDH in Japan were surveyed. Stomach herniation into the right chest was not uncommon and its grade correlated with outcome. The combination of liver and stomach positions was useful to stratify patients into three groups (Group I-III) with different prognoses.