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[en] The purpose of the present study was to compare differences in the depiction of small vessels in tumors on microangiograms obtained with a conventional soft X-ray system and with a synchrotron radiation (SR) system, and to evaluate the microangioarchitecture of these tumors and the process of their growth neovascularization. The SR system consisted of a monochromatic X-ray source of 37.6 keV just above the K absorption edge of barium and two fluorescent-screen CCD-camera lens-coupling systems. One of the CCD systems had a 24 μm equivalent pixel size and an input field size of 24x24 mm. The other system had a 6 μm equivalent pixel size and an input field of 6x6 mm. Microangiograms using the soft X-ray system depicted small vessels (diameter 20-50 μm), but the microangioarchitecture of the tumors could not be evaluated from conventional images. The monochromatic SR system allowed depiction of small vessels with a diameter of less than 25 μm. In addition, this system allowed us to confirm the process of growth neovascularization in the tumors

[en] The thermal radiation intensity from the mercury/sapphire interface shows an anomalous decrease in the prewetting supercritical region (Ohmasa et al 2000 J. Phys.: Condens. Matter 12 A375). This anomaly is a clear indication of the optical diffuse scattering caused by the critical fluctuations in the mercury wetting film formed on the sapphire substrate. In the present work, we measured the thermal radiation spectrum in the wavelength range 500 ∼< λ < 1650 nm, and deduced the diffuse scattering intensity as a function of λ. In this measurement, a new collimator system was employed to eliminate the contribution from the 'backing materials' behind the mercury/sapphire interface. Assuming an Ornstein-Zernike type permittivity correlation function, we have estimated the lateral correlation length and the interface width of the critical fluctuations to be several hundred nanometres and a few nanometres, respectively

[en] Nanostereolithography using evanescent light has been proposed as a means to realize submicrometer resolution. In this study, cured polymers of submicrometer thickness have been obtained using an evanescent light exposure apparatus. Examination of the controllability of the cure depth proves that the cure depth can be controlled at a standard deviation of at most 12 nm by configuring the polarization, the exposure energy, and the incident angle. The evanescent light photopolymerization process can be differentiated into two modes in terms of exposure energy per second. These results indicate that nanostereolithography can fabricate three-dimensional structures with submicrometer resolution

[en] Long wavelength infrared (LWIR) waves contain many important spectra of matters like molecular motions. Thus, probing spontaneous LWIR radiation without external illumination would reveal detailed mesoscopic phenomena that cannot be probed by any other measurement methods. Here we developed a scattering-type scanning near-field optical microscope (s-SNOM) and demonstrated passive near-field microscopy at 14.5 µm wavelength. Our s-SNOM consists of an atomic force microscope and a confocal microscope equipped with a highly sensitive LWIR detector, called a charge-sensitive infrared phototransistor (CSIP). In our s-SNOM, photons scattered by a tungsten probe are collected by an objective of the confocal LWIR microscope and are finally detected by the CSIP. To suppress the far-field background, we vertically modulated the probe and demodulated the signal with a lock-in amplifier. With the s-SNOM, a clear passive image of 3 µm pitch Au/SiC gratings was successfully obtained and the spatial resolution was estimated to be 60 nm (λ/240). The radiation from Au and GaAs was suggested to be due to thermally excited charge/current fluctuations and surface phonons, respectively. This s-SNOM has the potential to observe mesoscopic phenomena such as molecular motions, biomolecular protein interactions and semiconductor conditions in the future

[en] We have carried out small-angle x-ray scattering and x-ray transmission measurements of supercritical fluid Hg-0.2%Bi and pure Hg systems at SPirng-8 in Japan. We have obtained the static structure factors S(Q) in the low-momentum transfer region (0.5< Q <3 nm^-1) for both samples at temperatures and pressures up to 1600 deg. C and 200 MPa. A Bi-impurity effect can be seen in both S(Q) and density deduced from x-ray transmission, only in the high temperature and high pressure region; the sign of the phase separation is seen near the critical density for Hg-0.2%Bi sample. We have analyzed S(Q) by Ornstein-Zernike formula and deduced the structure factors in the long-wavelength limit S(0), correlation lengths ξ, and corresponding short-range correlation lengths R = ξ≡/√S(0). Temperature variation of R is very similar to that of the density in each sample. This experimental fact hints that the variation of R is highly dependent on its metallic nature because the density is the most relevant parameter for the electronic features in fluid Hg and its impurity systems

[en] Wide angle X-ray scattering measurements of sub- and supercritical water have been carried out using synchrotron radiation at SPring-8 in Japan, to study density dependence of the local structure. X-ray diffraction spectra were measured from 300 K to 1023 K at 40 MPa, and up to 1100 K at 100 MPa, corresponding to the density ρ from 1 g cm^-3 to 0.10 g cm^-3. The nearest neighbour distance and the nearest neibour coordination number depending on the density indcate that water is uniformly expanded from 1 g cm^-3 to 0.6 g cm^-3 with destruction of hydrogen bonding. With further volume expansion, the coordination number becomes approximately one at 0.15 g cm^-3 while the nearest neighbour distance is approximately 3.3 A. This experimental fact may be a first direct observation of dimeric molecules in the supercritical water.

[en] We have performed x-ray diffraction and small-angle x-ray scattering measurements for expanded fluid cesium from the triple point up to supercritical regions. The experimental results show that the nearest neighbor distance starts to decrease and the density fluctuation increases below the density around 1.3 g cm^-3. These structural features suggest that clustering occurs in the metallic fluid accompanying spatial atomic-density fluctuations. The density range where such inhomogeneity of the atomic arrangement appears corresponds to the region where the compressibility of the interacting electron gas has been predicted to become negative, which suggests that the observed structural changes are those induced by the instability of the electron gas

[en] We demonstrate a high-quality La_2O_3 layer on germanium (Ge) as an epitaxial high-k-gate-insulator, where there is an atomic-arrangement matching condition between La_2O_3(001) and Ge(111). Structural analyses reveal that (001)-oriented La_2O_3 layers were grown epitaxially only when we used Ge(111) despite low growth temperatures less than 300 °C. The permittivity (k) of the La_2O_3 layer is roughly estimated to be ∼19 from capacitance-voltage (C-V) analyses in Au/La_2O_3/Ge structures after post-metallization-annealing treatments, although the C-V curve indicates the presence of carrier traps near the interface. By using X-ray photoelectron spectroscopy analyses, we find that only Ge–O–La bonds are formed at the interface, and the thickness of the equivalent interfacial Ge oxide layer is much smaller than that of GeO_2 monolayer. We discuss a model of the interfacial structure between La_2O_3 and Ge(111) and comment on the C-V characteristics

[en] We have developed a special technique and succeeded to carry out small-angle x-ray scattering measurements for some liquid metal systems. The purpose is to investigate effects of transitions such as liquid–liquid (LLT), liquid–gas (LGT) and metal–nonmetal (MNMT) transitions on mesoscopic density fluctuations in liquids. In liquid Te systems (Se–Te and Ge–Te mixtures), which show continuous LLT accompanying MNMT, parameters of density fluctuations show maxima almost in the middle of the transition, both in strength and spatial size. This work (and Kajihara et al 2012 Phys. Rev. B86 214202) was the first direct observation that density fluctuations exhibit maximum corresponding to LLT. However in this study, we could not clearly separate the effects of LLT and MNMT on the observed density fluctuations. Thus, we also investigated fluid Hg under high pressure and high temperature conditions, which shows MNMT near a critical point of LGT, to investigate how MNMT affects them. We observed distinct density fluctuations; a strength and a correlation length of them show maxima at around a critical isochore of LGT, and the former is basically consistent with a phase diagram (compressibility) of LGT; they do not show any peaks at MNMT region. Precise analysis revealed that MNMT only affects a shift of another parameter, a short-range correlation length. These results in fluid Hg indicate that the density fluctuations are mainly derived from a critical phenomena of LGT and MNMT does not play any critical role on them. We believe that the latter conclusion also holds true for liquid Te systems; MNMT plays no important role on the density fluctuations in liquid Te systems and LLT is the main origin of them. (paper)