The electrochemical oxidation behaviors of the surfaces of platinum nanoparticles, one of the key phenomena in fuel cell developments, were investigated in situ and in real time, via time-resolved hard X-ray diffraction and energy dispersive X-ray absorption spectroscopy. Combining two complementary structural analyses, dynamical and inhomogenous structural changes occurring at the surfaces of nanoparticles were monitored on an atomic level with a time resolution of less than 1 s. After oxidation at 1.4 V vs RHE (reversible hydrogen electrode) in a 0.5 M H(2)SO(4) solution, longer Pt-O bonds (2.2-2.3 A that can be assigned to OHH and/or OH species) were first formed on the surface through the partial oxidation of water molecules. Next, these species turned to shorter Pt-O bonds (2.0 A, adsorbed atomic oxygen), and atomic oxygen was incorporated into the inner part of the nanoparticles, forming an initial monolayer oxide that had alpha-PtO(2)-like local structures with expanded Pt-Pt bonds (3.1 A). Finally, quasi-three-dimensional oxides with longer Pt-(O)-Pt bonds (3.5 A, precursor for beta-PtO(2)) grew on the surface, at almost 100 s after oxidation. Despite the very complex oxidation mechanism on the atomic level, XANES analysis indicated that the charge transfer from platinum to the adsorbed oxygen species was almost constant and rather small, that is, about 0.5 electrons per oxygen, up to two monolayers of oxygen. This means that ionic polarization hardly develops at this stage of the surface platinum's "oxide" growth.

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The energy spectra of cosmic-ray low-energy antiprotons (p's) and protons (p's) have been measured by BESS in 1999 and 2000, during a period covering the solar field reversal. Based on these measurements, a sudden increase of thep/p flux ratio following the solar field reversal was observed as predicted by a drift model of the solar modulation.PACS numbers: 98.70. Sa, 96.40.Kk, 95.85.Ry The real underlying physics of the sun is the 22 year solar magnetic cycle with recurrent positive and negative phases. The magnetic field polarity flips when the solar activity is maximum and the global magnetic field profile reverses in the heliosphere. The most recent field reversal should happen in the beginning of 2000. The solar modulation of cosmic rays is caused by expanding solar wind, which spreads out locally irregular magnetic field and therefore modifies energy spectra of the cosmic rays entering the heliosphere. The positive and negative particles drift in opposite directions, during their propagation in the large scale heliospheric magnetic field. The charge-sign dependence is, therefore, a natural consequence [1] in the solar modulation, and it explains alternate appearances of "flat" and "peaked" periods in neutron monitor data around solar minima. In spite of an emerging understanding that the drift became unimportant for several years around the solar maximum [2], recent works [3][4][5] indicated that the drift produces a strong differentiation between the positive and negative particles even during the high solar activity. This view is supported by measurements of temporal variation in cosmic-ray ratios, such as electrons to helium nuclei (He) [6] and electrons to protons (p's) [7], where the largest variation is associated with the solar field reversal. Antiprotons (p's) and their ratio to p's may be novel probes to study the solar modulation becausep's differ from p's only in the charge sign while electrons would behave differently from He and p's due to their lighter mass [4].In the last solar minimum period, the BESS experiment revealed that the cosmic-rayp spectrum has a distinct peak around 2 GeV [8], which is a characteristic feature of secondaryp's produced by cosmic-ray interactions with interstellar (IS) gas. It has become evident thatp's are predominantly secondary in origin, because several recent calculations of the secondary spectrum basically agree with observations in their absolute values and spectral shapes [4,5,9,10].We report here new measurements of cosmic-rayp and p fluxes and their ratios in the energy range from 0.18 to 4.2 GeV collected in two BESS balloon flights carried out in 1999 and 2000, when the solar activity was maximum. Based on the solar magnetic field data [11], the Sun's polarity reversed between these two flights [12]. With our full set of data [8,[13][14][15], we observed the temporal variation of thep flux andp/p ratio covering the solar minimum, the maximum, and the field reversal.The BESS spectrometer was designed [16,17] and developed [18-21] as a high-resolution ...

The short-range order of molten silicon was investigated in a wide temperature range from 1893 K down to 1403 K, corresponding to an undercooling of 290 K. Energy-dispersive x-ray diffraction was used in combination with electromagnetic levitation. The structure factor and the pair correlation function were determined as a function of temperature from the experimental data. A small hump on the higher wave vector side of the first peak in the structure factor was observed at all temperatures. The position of the first peak in the pair distribution function shifted to shorter distances and its height increased gradually with decreasing temperature. No discontinuous behavior was observed in the entire temperature range investigated.

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Mixed crystal films of Ca x Cd 1−x F 2 were epitaxially grown on Si(111) substrates covered with a thin CaF 2 buffer layer. Using the molecular-beam epitaxy method, 110-nm-thick mixed crystal films were grown at 200 • C on 10-nm-thick CaF 2 buffer layers on Si(111). Rutherford backscattering spectroscopy revealed that the composition of the mixed crystal layer, x, was consistent with the flux ratio of a CaF 2 molecular beam and a CdF 2 molecular beam, and that channeling minimum yields of less than 20% were obtained for the entire range of composition (x = 0 to x = 1). Very smooth surface morphology with 0.29 nm of rms was obtained for the x = 0.31 layer, compared to those of pure CaF 2 or CdF 2 layers grown at the same growth temperature.

When compared with ODG, LADG contributes to the preservation of postsurgical Th1 cell-mediated immune function.

The only difference between our two study groups was that LDG required a longer operating time in obese patients; morbidity and length of hospital stay were not increased. Thus, we believe that LDG is likely to become the treatment of choice for obese patients with early gastric cancer.