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Simple liquid-phase approaches for the synthesis of nanomaterials are attractive because their low costs, reduced nanoparticle aggregation, and compatibility with subsequent liquid processes widen the application scope of the resulting materials. This would be particularly interesting for β-Ga2O3 nanoparticles, which often suffer from aggregation issues during their synthesis processes. In this paper, we report a one-step synthesis of β-Ga2O3 nanoparticles in supercritical isopropanol. By simply heating Ga(NO3)3 in isopropanol at 400 °C for 24 hours, β-Ga2O3 nanoparticles with a size of ∼100 nm are obtained without requiring additional calcination in air. A structural characterization comprising X-ray diffraction, scanning electron microscopy, selected-area electron diffraction with transmission electron microscopy, and X-ray absorption fine structure measurements suggest that the synthesis process involves an initial conversion of Ga(NO3)3 to Ga(Oi-Pr)3 or a related species at 80 °C, which then transforms into γ-Ga2O3 nanoparticles upon increasing the temperature, to eventually produce β-Ga2O3 nanoparticles most likely via a dissolution and recrystallization process.

CaCO3 is used by many invertebrates for biomineralization. Organic materials in biominerals stabilize amorphous CaCO3 (ACC). Investigation of biomineral formation requires analysis of ACC. X-ray ab...

Characterization of the fuel debris has been required for decommissioning Fukushima Daiichi Nuclear Power Station. To understand the reaction mechanisms involved for mixed UO2 – ZrO2 compounds, these materials were treated at high temperatures (1473 to 1873 K) under oxidizing, inert, and reducing atmospheres. The reaction products were analysed by a combination of powder X-ray diffraction (PXRD) and X-ray absorption spectroscopic measurements of the U LIII- and Zr K-edges. Principal component analysis of the X-ray absorption near edge structure and extended X-ray absorption fine structure of U LIII- and Zr K-edges provided a breakdown of the composition of each species within the products, these results were further supported by PXRD. Under an oxidizing atmosphere, the formation of U3O8 and U2Zr5O15 was observed in equilibrium with UO2, monoclinic-ZrO2, and tetragonal-ZrO2. However, when O2 gas was purged through the reaction tube during the cooling process to room temperature, pentavalent U in ZrU2O7 was produced by the oxidation of solid solution UO2 formed at > 1774 K during the temperature dropped at 1673 K due to a low concentration of O2 impurity with the Ar gas. Although the oxidized UO2 was able to form in such a system, tetravalent UO2 and its solid solution were instead present throughout the whole temperature range examined under a reducing atmosphere (H2 gas). This study can pave the way for understanding the interaction between the nuclear fuels and the cladding materials in damaged reactors enabling further simulation of possible decontamination procedures.

Polyacrylic acid (PAA)-modified titanium peroxide nanoparticles (PAA-TiOx NPs) are promising radiosensitizers. PAA-TiOx NPs were synthesized from commercial TiO2 nanoparticles that were modified with PAA and functionalized by H2O2 treatment. To realize practical clinical uses for PAA-TiOx NPs, their tissue distribution and acute toxicity were evaluated using healthy mice and mice bearing tumors derived from xenografted MIAPaCa-2 human pancreatic cancer cells. Healthy mice were injected with PAA-TiOx NPs at 25 mg/kg body weight via the tail vein, and tumor-bearing mice were injected either into the tumor locally or via the tail vein. The concentration of PAA-TiOx NPs in major organs was determined over time using inductively coupled–plasma atomic emission spectrometry. After 1 h, 12% of the PAA-TiOx NP dose had accumulated in the tumor, and 2.8% of the dose remained after 1 week. Such high accumulation could be associated with enhanced permeability and retention effects of the tumor, as PAA-TiOx NPs are composed of inorganic particles and polymers, without tumor-targeting molecules. The liver accumulated the largest proportion of the injected nanoparticles, up to 42% in tumor-bearing mice. Blood biochemical parameters were also investigated after intravenous injection of PAA-TiOx NPs in healthy mice. PAA-TiOx NPs invoked a slight change in various liver-related biochemical parameters, but no liver injury was observed over the practical dose range. In the future, PAA-TiOx NPs should be modified to prevent accumulation in the liver and minimize risk to patients.

Characterization of uranium accumulated in the micro-regions of renal tubules of rats exposed to uranyl acetate was examined by micro-X-ray absorption fine-structure analysis and the results showed the possible biotransformation of uranium in this in vivo system., The kidney is the critical target of uranium exposure because uranium accumulates in the proximal tubules and causes tubular damage, but the chemical nature of uranium in kidney, such as its chemical status in the toxic target site, is poorly understood. Micro-X-ray absorption fine-structure (µXAFS) analysis was used to examine renal thin sections of rats exposed to uranyl acetate. The U L III-edge X-ray absorption near-edge structure spectra of bulk renal specimens obtained at various toxicological phases were similar to that of uranyl acetate: their edge position did not shift compared with that of uranyl acetate (17.175 keV) although the peak widths for some kidney specimens were slightly narrowed. µXAFS measurements of spots of concentrated uranium in the micro-regions of the proximal tubules showed that the edge jump slightly shifted to lower energy. The results suggest that most uranium accumulated in kidney was uranium (VI) but a portion might have been biotransformed in rats exposed to uranyl acetate.

Although the kidneys comprise a critical target of uranium exposure, the dynamics of renal uranium distribution have remained obscure. Uranium is considered to function physiologically in the form of uranyl ions that have high affinity for phosphate groups. The present study applied microbeam-based elemental analysis to precisely determine the distribution of phosphorus and uranium in the kidneys of male Wistar rats exposed to uranium. One day after a single subcutaneous injection of uranyl acetate (2 mg/kg), areas of concentrated phosphorus were scattered in the S3 segments of the proximal tubule of the kidneys, whereas the S3 segments in control rats and in rats given a lower dose of uranium (0.5 mg/kg) contained phosphorus without concentrated phosphorus. Areas with concentrated phosphorus contained uranium 4- to 14-fold more than the mean uranium concentration (126&ndash, 472 vs. 33.1 &plusmn, 4.6 &mu, g/g). The chemical form of uranium in the concentrated phosphorus examined by XAFS was uranium (VI), suggesting that the interaction of uranyl ions with the phosphate groups of biomolecules could be involved in the formation of uranium concentration in the proximal tubules of kidneys in rats exposed to uranium.

Polyacrylic acid-modified titanium peroxide nanoparticles (PAA-TiOx NPs) are promising radiosensitizers that enhance the therapeutic effect of X-ray irradiation after local injection into tumors. However, the mechanism for this reaction has remained unclear with the exception of the involvement of hydrogen peroxide (H2O2), which is released by PAA-TiOx NPs to a liquid phase during dispersion. In the present study, a clonogenic assay was used to compare PAA-TiOx NPs with free H2O2 molecules to investigate the effect exerted on the radiosensitivity of cancer cells in vitro. A cell-free dialysis method revealed that a portion of the H2O2 adsorbed onto the PAA-TiOx NPs during synthesis could be released during a treatment regimen. The H2O2 release lasted for 7 h, which was sufficient for one radiation treatment procedure. For in vitro experiments, cultured human pancreatic cancer cells took up PAA-TiOx NPs in 10 min after administration. Interestingly, when the cells were washed with a buffer after treatment with either a PAA-TiOx NP or H2O2 solution, the intracellular H2O2 levels remained higher with PAA-TiOx NP treatment compared with the H2O2 solution treatment. Furthermore, the effects of subsequent X-ray irradiation corresponded to the intracellular H2O2 levels. These results indicate that PAA-TiOx NPs are efficient carriers of H2O2 into cancer cells and thus enhance the radiosensitivity.

An induction of polyacrylic acid-modified titanium dioxide with hydrogen peroxide nanoparticles (PAA-TiO2/H2O2 NPs) to a tumor exerted a therapeutic enhancement of X-ray irradiation in our previous study. To understand the mechanism of the radiosensitizing effect of PAA-TiO2/H2O2 NPs, analytical observations that included DLS, FE-SEM, FT-IR, XAFS, and Raman spectrometry were performed. In addition, highly reactive oxygen species (hROS) which PAA-TiO2/H2O2 NPs produced with X-ray irradiation were quantified by using a chemiluminescence method and a EPR spin-trapping method. We found that PAA-TiO2/H2O2 NPs have almost the same characteristics as PAA-TiO2. Surprisingly, there were no significant differences in hROS generation. However, the existence of H2O2 was confirmed in PAA-TiO2/H2O2 NPs, because spontaneous hROS production was observed w/o X-ray irradiation. In addition, PAA-TiO2/H2O2 NPs had a curious characteristic whereby they absorbed H2O2 molecules and released them gradually into a liquid phase. Based on these results, the H2O2 was continuously released from PAA-TiO2/H2O2 NPs, and then released H2O2 assumed to be functioned indirectly as a radiosensitizing factor.

Individual distribution constants (KD,A) of picrate ion (Pic−) and extraction constants (Kex±) of NaPic by some crown ethers (L) into benzene (Bz) at 25°C were calculated from data reported previously. These constants were defined asKD,Pic=Pic-o/[Pic-]andKex±=NaL+oPic-o/(Na+Lo[Pic-]), respectively. Here, the subscript “o” denotes an organic (o) phase and practically o = Bz. 15-Crown-5 ether (15C5), 18-crown-6 one (18C6), and their monobenzo (B) derivatives (B15C5 and B18C6) were selected as L. Interfacial equilibrium-potential differences (Δϕeq) at extraction were estimated at 298 K. A plot oflog⁡Kex±versus-Δϕeqfor the four L extraction systems gave a straight line with slope = 84 V−1. This slope was compared with those, reported before, of the dichloromethane (DCM), 1,2-dichloroethane (DCE), and nitrobenzene (NB) extraction systems. The slopes of the regression lines were in the order NB < DCM ≤ DCE < Bz. Also, the individual distribution constants of the complex ionNaL+and an ion-pair complex (NaL+Pic-) into Bz phase were calculated from the above extraction data. At least, a comparison between these values suggests that Bz molecules mainly interact withNaL+moiety ofNaL+Pic-.

Kidneys are critical targets of uranium exposure, meaning that effective analytical methods for characterizing uranium accumulated in kidneys are required in toxicological studies of uranium. In this work, synchrotron radiation micro-X-ray fluorescence (SR-μXRF) imaging and two-dimensional μXAFS measurements were combined to analyze renal section specimens. By histochemical staining of the serial sections, the distribution of uranium chemical condition within the uranium-concentrated areas of the proximal tubules, which are toxic target sites of uranium, were obtained with 1 µm × 1 µm spatial resolution.

Silicalite-1 zeolites with high manganese contents isomorphously incorporated within the framework were synthesized by using mechanochemical pretreatment. First, manganese and silica sources were mixed in a planetary ball mill to obtain a composite material comprised of Mn, Si, and O. The composite was subsequently hydrothermally treated to crystallize Silicalite-1 zeolites. The synthesis was performed using a condition with a small amount of water to directly convert the composite material into a zeolite crystal while preventing manganese from leaching into water, which may cause manganese oxide/hydroxide species to precipitate. X-ray fluorescence analysis showed that the obtained products displayed a high manganese content of up to 6.3 mol%. The importance of utilizing mechanochemical treatment was confirmed through a number of characterization techniques, such as X-ray diffraction, catalytic activity assessments, diffuse reflectance UV-vis spectroscopy, Raman spectroscopy, and X-ray absorption fine structure analysis. Our findings suggest that this procedure using mechanochemical pretreatment can produce zeolites with various heteroatoms within their framework structures at contents difficult to achieve through conventional methods.

Extraction constants for lead picrate, PbPic2, with 18-crown-6 ether (L) from aqueous solutions at a narrow range of ionic strength (I) into eleven diluents were determined at 298 K by AAS measurements. These constants were defined as Kex = [PbLPic2]o/([Pb2 +][L]o[Pic−]2) and Kex ± = [PbLPic+]o[Pic−]o/([Pb2 +][L]o[Pic−]2), where the subscript “o” denotes the organic phase (or diluent). The ratio, Kex/Kex ±, gave an ion-pair formation constant for PbLPic + o + Pic − o ⇌ PbLPic 2 , o at the averaged value of ionic strength (Io) of the organic phase. A plot of log Kex ± versus log KD,Pic yielded a straight line with the slope of 2.1 in a series of the diluents employed; KD,Pic refers to an apparent distribution constant of Pic− between the aqueous and organic phases and its values were experimentally determined. The slope indicated that Kex ± is mainly controlled by the square of KD,Pic when a thermodynamic cycle is assumed. The extraction constant based on the cycle was expressed as Kex ± = (KD,Pic)2KD,MKML,orgK1,org, where KD,MKML,orgK1,org denotes the product of other component equilibrium-constants. Moreover, the relation of log KD,Pic = alog (Io/I) + b was experimentally found at a ≈ 1 and then an example of b was expressed theoretically. It was shown that Pb(II) can be separated from mixtures with Cd(II) in unit operation.

An induction of polyacrylic acid-modified titanium dioxide with hydrogen peroxide nanoparticles (PAA-TiO

Background Biological applications of nanoparticles are rapidly increasing, which introduces new possibilities to improve the efficacy of radiotherapy. Here, we synthesized titanium peroxide nanoparticles (TiOxNPs) and investigated their efficacy as novel agents that can potently enhance the effects of radiation in the treatment of pancreatic cancer. Methods TiOxNPs and polyacrylic acid-modified TiOxNPs (PAA-TiOxNPs) were synthesized from anatase-type titanium dioxide nanoparticles (TiO2NPs). The size and morphology of the PAA-TiOxNPs was evaluated using transmission electron microscopy and dynamic light scattering. The crystalline structures of the TiO2NPs and PAA-TiOxNPs with and without X-ray irradiation were analyzed using X-ray absorption. The ability of TiOxNPs and PAA-TiOxNPs to produce reactive oxygen species in response to X-ray irradiation was evaluated in a cell-free system and confirmed by flow cytometric analysis in vitro. DNA damage after X-ray exposure with or without PAA-TiOxNPs was assessed by immunohistochemical analysis of γ-H2AX foci formation in vitro and in vivo. Cytotoxicity was evaluated by a colony forming assay in vitro. Xenografts were prepared using human pancreatic cancer MIAPaCa-2 cells and used to evaluate the inhibition of tumor growth caused by X-ray exposure, PAA-TiOxNPs, and the combination of the two. Results The core structures of the PAA-TiOxNPs were found to be of the anatase type. The TiOxNPs and PAA-TiOxNPs showed a distinct ability to produce hydroxyl radicals in response to X-ray irradiation in a dose- and concentration-dependent manner, whereas the TiO2NPs did not. At the highest concentration of TiOxNPs, the amount of hydroxyl radicals increased by >8.5-fold following treatment with 30 Gy of radiation. The absorption of PAA-TiOxNPs enhanced DNA damage and resulted in higher cytotoxicity in response to X-ray irradiation in vitro. The combination of the PAA-TiOxNPs and X-ray irradiation induced significantly stronger tumor growth inhibition compared to treatment with either PAA-TiOxNPs or X-ray alone (p

The combined application of hydroxyapatite and ferrihydrite can simultaneously immobilize lead and antimony(V) in oxic soil. However, this has not been demonstrated for antimony(III). In this study, antimony(III) sorption experiments in solution and dissolution experiments in oxic soil were conducted using the combined application of hydroxyapatite and ferrihydrite to elucidate the contribution of the materials to antimony(III) sorption and to evaluate the amount of antimony dissolved from the antimony(III)-sorbed materials by the change in redox state in oxic soil. All the antimony(III) in 50 mg l−1 solution at pH 5 was sorbed on the combined materials without oxidation. The contribution of ferrihydrite and hydroxyapatite on antimony(III) sorption was 92.6 and 7.4 %, respectively. The antimony(III) sorbed on the combined materials was not oxidized within 7 days of incubation period in oxic soil. However, after 90 days of incubation period, all the antimony(III) was oxidized to antimony(V). The percentage of antimony dissolution from the simulative-immobilized soil with the antimony(III)-sorbed combined material was constant at less than 1 % during incubation periods. Therefore, no enhancement in the antimony soil mobility in the soil with the combined application was observed, although antimony(III) was oxidized. These results suggest that the combined application of hydroxyapatite and ferrihydrite could immobilize antimony(III) without re-dissolving antimony through oxidation. Thus, the combined application would be applicable to lead- and antimony-contaminated soil.

Details of the synthetic protocol for PAA-TiOxNPs formation from TiO2NPs. (PPTX 151Â kb)

Effect of SiO2 addition on the microstructures of calcium-deficient hydroxyapatite prepared by the heat-treatments was examined. Obtained hydroxyapatites substituted with Si ion were characterized by XRD, FT-IR and XAFS measurements. XANES results of Si K-edge and P K-edge in these modified hydroxyapatites indicated the shift of peaks of P K-edge with the SiO2 contents, although no change of Si local structures. In this study, the effect of Si ion on micro- and local structure of hydroxyapatite with SiO2 addition was mainly clarified.

Manganese-incorporated MCM-41 with high manganese content of Mn/(Mn + Si) = 9.2 mol % and BET specific surface area of 750 m2 g−1 was obtained by utilizing mechanochemical treatment. Clear differen...

The structural change on the molecular scale of anatase-type TiO(2) during hydrothermal treatment was investigated in detail by various analytic techniques such as X-ray absorption fine structure and transmission electron microscopy in order to clarify the formation mechanisms of titanate-based nanotubes. It revealed that the nanosheet-like products composed of highly distorted TiO(6) octahedra were generated by hydrothermal treatment of anatase-type TiO(2), and then the anatase-like structures are partially built up with the formative nanotubes by scrolling up these nanosheet-like products and nanosheets.

Oral lichen planus (OLP) and oral lichenoid contact lesions (OLCL) are chronic inflammatory mucocutaneous reactions with a risk of malignant transformation that alter the epithelium. OLP and OLCL have similar clinical and histopathological features and it is difficult to distinguish one from the other. Metallic restorations are suspected to generate OLCLs. Trace metal analysis of OLCL specimens may facilitate the discrimination of symptoms and identification of causative metallic restorations. The purpose of this study was to assess OLCL tissue samples for the prevalence of metallic elements derived from dental restorations and to discriminate OLCL from OLP by using synchrotron radiation-excited X-ray fluorescence analysis (SR-XRF), particle-induced X-ray emission (PIXE) and X-ray absorption fine structure (XAFS). Typical elements of dental materials were detected in the OLCL, whereas no obvious element accumulation was detected in OLP and negative control specimens. The origin of the detected metallic elements was presumed to be dental alloys through erosion. Therefore, our findings support the feasibility of providing supporting information to distinguish OLCL from OLP by using elemental analysis.

The origin of the ruby color of Satsuma glass, a famous copper-ruby glass produced in Japan in the mid-19th century, has been examined by electron microprobe analysis (EPMA), X-ray absorption fine structure (XAFS), and optical absorption spectroscopy analyses. CuK XAFS analysis reveals that the major component of copper in the ruby glass consists of Cu(I) ions in the glass structure. This species is distinct from Cu2O (cuprite), which we conclude is not responsible for the ruby color. Optical absorption spectra measured at 300 and 77 K clearly distinguishes the absorptions due to the colloidal particles of metallic copper and Cu2O. It is concluded that the trace amount of copper in the ruby glass, which is below the detection limit of the EPMA and XAFS techniques, exists as metallic copper particles of nanometer size and is responsible for the ruby-red appearance of the Satsuma glass.

A new intermediate phase called X-phase in this work has been found in the early stage of dehydration process of gibbsite to χ-alumina by powder X-ray diffraction method. The X-phase appears in the temperature range between 240°C and 350°C. The intensity of X-ray diffraction peak of the X-phase became maximum at 250°C and after that decreased gradually and disappeared approximately at 350°C for the sample heated for 11 hours.

Ten mole percent ytterbium-doped SrZrO 3 , which has the highest proton conductivity among the ytterbium-doped SrZrO 3 , has been studied by X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) to elucidate the effect of dopant amount of ytterbium ions. The results are compared with those of 5 mol% ytterbium-doped SrZrO 3 of our previous work. The orthorhombic unit cell volume increases monotonously with increasing temperature but exhibits a bent between 500 and 600 °C, which is about 300 K lower than that of 5 mol% ytterbium-doped SrZrO 3 and then increases again with temperature. This bent of the unit cell volume is considered to be due to a loss of oxygen, which is consistent with the result of a weight loss in TGA observed in the same temperature range. The weight loss and gain on heating and on cooling, respectively, were observed in TGA but do not exhibit so clear hysteresis loop as observed for 5 mol% ytterbium-doped SrZrO 3 . The displacements of oxide ions were observed in the Fourier syntheses followed by a loss of oxygen at high temperature.

An efficient Johansson-type X-ray fluorescence spectrometer has been developed for advanced X-ray spectroscopic analysis with third-generation synchrotron radiation. Kalpha and Kbeta X-ray fluorescence spectra for trace metals have been collected by a Ge(220) analyzing crystal with a Rowland radius of 150 mm, under monochromatic X-ray excitation at the undulator beamline at the SPring-8. The energy resolution is approximately 10 eV for most of the K lines for 3d transition metals. In light of the greatly improved efficiency, as well as the excellent signal-to-background ratio, the relative and absolute detection limits achieved are 1 ppm and 1.2 ng of copper in a carbon matrix, respectively. The energy resolution of the present spectrometer permits the observation of some chemical effects in Kbeta spectra. It has been demonstrated that the changes in Kbeta5 and Kbeta'' intensity for iron and cobalt compounds can be used for the analysis of chemical states. Resonant X-ray fluorescent spectra are another important application of monochromatic excitation. In view of trace chemical characterization, the present spectrometer can be a good alternative to a conventional Si(Li) detector system when combined with highly brilliant X-rays.

Ytterbium-doped SrZrO3 has been studied by thermogravimetric analysis (TGA), differential thermal analysis (DTA), powder X-ray diffraction (XRD), and XAFS spectroscopy. A broad endothermic peak was observed in the DTA curve for 5 mol% Yb-doped SrZrO3 at 812°C, accompanied with a small weight loss, which is considered due to a mass loss of oxygen. The weight recovered its value in the cooling process at the lower temperature of 740°C. The weight loss and gain in the heating and cooling process, respectively, shows a hysteresis loop. There exist at least 2.3 atom% oxide ion vacancies at high temperature. The two lattice constants become the same value above about 800°C, indicating a phase transition for 5 mol% Yb-doped SrZrO3, which is consistent with the results from TGA and DTA. The oxide ion vacancies produced by substitution of tetravalent zirconium ions by trivalent ytterbium ions are localized not near zirconium ions, but near ytterbium ions.

The fluorescence XAFS (X–ray absorption fine structure) technique using synchrotron radiation was applied to characterize zinc in the Hg–Zn, Cd–Zn, and Bi–Zn coprecipitates, and to elucidate the reaction mechanism of the coprecipitation of zinc from a strong acidic solution. Hg LII–, Cd K–, and Bi LIII–edge XAFS spectra suggested that the respective host materials of the coprecipitates listed above are metacinnabar (HgS), greenockite (CdS), and bismuthinite (Bi2S3) and that existence of zinc has not affected the local structure of the host metal sulfides in each system. On the other hand, the Zn K–edge XAFS spectra of each coprecipitate indicated that the chemical forms of zinc compounds are controlled by the crystal structure of the host sulfides.The shapes of the Zn K–XAFS spectra of the Hg–Zn and Cd–Zn coprecipitates showed a strong resemblance to those of crystalline standards ZnS, wurtzite and spharelite. It was suggested that the two coprecipitated phases (HgS, ZnS) and (CdS, ZnS) may form a solid solution in the Hg–Zn and Cd–Zn coprecipitates. The local structure around the zinc(II) ion in the Bi–Zn coprecipitate is the same as that around hexaaqua–zinc(II) ions, and adsorption of soluble ions or mechanical occlusion from the mother liquor is regarded as a driving force of coprecipitation in the Bi–Zn system.

Local structure around arsenic atoms in K-T boundary clays was studied by As K-edge XAFS spectroscopy. The threshold E0 energy of As and the characterization of the white peak of XANES spectra agree well with the values of As(+5) minerals like Zn2(AsO4)2(OH) 22H2O and CaCu(AsO4)(OH) according to the comparison with several types of arsenic minerals. This indicates that arsenic is in a high oxidation state As(+5) and occupies the AsO4 tetrahedral site of a mineral in K-T boundary clays.

The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase.

International audience; Four calcium silicate hydrates (C-S-H) with structural calcium/silicon (Ca/Si) ratios ranging from 0.82 +/- 0.02 to 0.87 +/- 0.02 were synthesized at room temperature, 50, 80, and 110 degrees C. Their structure was elucidated by collating information from electron probe micro-analysis, transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, and powder X-ray diffraction (XRD). A modeling approach specific to defective minerals was used because sample turbostratism prevented analysis using usual XRD refinement techniques (e.g. Rietveld analysis). It is shown that C-S-H with Ca/Si ratio of similar to 0.8 are structurally similar to nano-crystalline turbostratic tobermorite, a naturally occurring mineral. Their structure thus consists of sheets of calcium atoms in 7-fold coordination, covered by ribbons of silicon tetrahedra with a dreierketten (wollastonite-like) organization. In these silicate ribbons, 0.42 Si per bridging tetrahedron are missing. Random stacking faults occur systematically between successive layers (turbostratic stacking). Layer-to-layer distance is equal to 11.34 angstrom. Crystallites have a mean size of 10 nm in the a-b plane, and a mean number of 2.6-2.9 layers stacked coherently along the c* axis. (C) 2013 Elsevier Ltd. All rights reserved.

The variation of iron chemical forms during the teeth formation of chiton was clarified by utilizing the fluorescence XAFS technique. Fe K-XANES spectra of the teeth of chiton in various maturation stages show a complex oxidation/reduction process of iron during the teeth formation. In the earliest stage of the maturation, an amorphous ferritin-like ferric compound accumulates in the teeth. Magnetite formation occurs abruptly in the next maturation stage, and the color of the teeth changes from reddish brown to gray. The spectra of the teeth in the latter maturation stages show that the edge-energy is higher than that of magnetite. These results suggest that the fully mineralized teeth are considered to be a mixture of magnetite and a ferric compound.

ピザラガイは,鉄を高濃度に濃集した歯を形成し,この歯が磁性を持つことからユニークな存在として注目されている.鉄を濃集した歯は基底膜の上に約70対存在し,その成熟過程で形状が変化するが,本研究ではそれに伴う鉄の化学形の変化を調べるためにシンクロトロン放射光を利用するX線吸収微細構造(XAFS)法を適用した.X線回折の測定からは結晶成分としては磁鉄鉱のみが検出され,更にX線プローブマイクロアナリシス(EPMA)により鉄は歯の先端部から腹側にかけての摂餌面に局在していることが確認された.蛍光XAFS測定の結果,歯の形成初期の段階では鉄は三価の非晶質酸化水酸化物(FeOOH)として沈着され,その後部分的に還元を受け二価と三価の混合した磁鉄鉱(Fe3O4)を形成してゆくことが明らかとなった.又,ピザラガイの歯は成熟過程において,褐色,灰色,赤色,黒色と4段階の変色を示すが,歯に含まれる鉄の状態もこれに伴い変化しており,歯の外観と鉄の化学形に相関があることが分かった.

In this study, the effect of post acid treatments with HCl aqueous solutions after the hydrothermal process on the microstructure of TiO2-derived titanate nanotube was investigated. Especially, the relationship between local structural changes with the HCl treatment and their thermal stability were investigated by X-ray absorption fine structure (XAFS). Consequently, it revealed that the replacement of Na+ with H+ (proton exchange) in TiO2-derived titanate nanotubes was caused by the acid treatment with HCl aqueous solutions and the excess acid treatment led to the disordering. Moreover, it was confirmed that the minor change of TiOx polyhedra in TiO2-derived titanate nanotubes was also related with this disordering.

Chemical conditions and mass transport properties of engineered barrier systems in TRU waste facilities would change with time due to the interaction of cement/bentonite materials. (‘TRU waste’ is one of categories of the radioactive wastes and contains a significant amount of alpha-emitting transuranic nuclides. In some countries, these wastes are classified into the Intermediate Level Waste (ILW).) Previous numerical model analyses to assess the long-term performance of engineered barrier systems in TRU waste repositories predicted to form Calcium Silicate Hydrate (C-S-H) species at the interface between the cementitious and bentonite materials. If C-S-H precipitates in the bentonite side of the boundary, mass transport in the bentonite buffer decreases and mineralogical alterations are expected to be restricted for a long period. The evidence of C-S-H precipitation in the bentonite side, however, still has not been identified in the former experimental studies. To improve the reliability of numerical analyses, immersion experiments were performed using contact samples of cementitious and bentonite materials, and X-ray absorption fine structure (XAFS) analysis was carried out to detect C-S-H precipitation at the contacting interface. Precipitation of C-S-H was confirmed from the obtained XAFS spectra. This result is one of the evidences to show the validity of the current numerical model analyses, which suggests that the bentonite buffer performance as an engineered barrier would be kept over a long period.

Purpose: Pancreatic cancer is a highly lethal disease and notoriously resistant to many types of cytotoxic chemotherapy and radiotherapy. A novel strategy should be explored for these radioresistant tumors. We originally synthesized a titanium peroxide nanoparticle (TiOxNP) which had a distinct ability to produce reactive oxygen species (ROS) upon X-ray irradiation (IR). Here, the characterization and efficacy of TiOxNP as radiosensitizer for pancreatic cancer therapy were investigated. Methods: TiOxNPs were synthesized from anatase titanium oxide nanoparticles (TiO2NPs) by H2O2 processing and coated by polyacrylic acid. The ability of TiOxNPs to enhance ROS generation upon X-ray irradiation (IR) was tested by using 3′-(p-Aminophenyl) fluorescein and several antioxidants. A xenograft mouse model using the human pancreatic cancer cell line MIAPaCa-2 was used to evaluate the cytotoxic effects of a combination of TiOxNPs and IR in vivo. MIAPaCa-2 cells were injected subcutaneously into the hind legs of immunodeficient BALB/c mice. Seven days after injection, the tumor was treated with a TiOxNP suspension injected directly into the tumor and application of 5 Gy of IR. Tumor size and health of the mice were monitored for 43 days after the treatment. Induction of apoptosis was evaluated by immunohistochemistry using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling staining. We also characterized TiOxNPs by ESR and XAFS analyses. Results: ROS generation was enhanced dramatically by TiOxNPs in a concentration- and radiation dose- dependent manner compared to enhancement by TiO2NPs. At the highest concentration of TiOxNPs, ROS generation upon an irradiation dose of 30 Gy was enhanced by a factor of more than 10. Also, ROS generated by TiOxNPs upon IR were scavenged by vitamin C or glutathione. Growth inhibition of the tumor in the group receiving both TiOxNP and IR was significantly greater than single treatment subgroups (P < 0.05). The number of apoptotic cells was also significantly higher in the combination group (P < 0.05). Histologically, large pools of TiOxNPs around tumor cells and small amounts inside the tumor cells were observed. No mice died within a 43-day observation period or showed any apparent body weight loss. In the ESR spectra, some signals were observed for TiOxNPs. The spectral shapes of Ti K-edge X-ray absorption near edge structure, spectra were the same among the mineral anatase, TiO2NPs and TiOxNPs. Conclusions: TiOxNPs induced remarkable ROS production upon IR. They were safe and effective in a xenograft mouse model using engrafted human pancreatic cancer cells. Further studies would be necessary to elucidate a mechanism of radical generation and long-term toxicity, however our study shows that TiOxNPs are promising radiosensitizers for application in pancreatic cancer therapy. Citation Format: Masao Nakayama, Ryohei Sasaki, Toru Mukohara, Chiaki Ogino, Kenta Morita, Mitsuo Umetsu, Satoshi Ohara, Kazuyoshi Sato, Chiya Numako, Seiichi Takami, Akihiko Kondo. Titanium peroxide nanoparticles enhance antitumor efficacy through reactive oxygen species in pancreatic cancer radiation therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3337. doi:10.1158/1538-7445.AM2015-3337

Size-controllable TiO2 nanosheets with highly exposed {001} facets were synthesized by a hydrothermal method. The particle sizes ranged from 25 nm to submicrometres by carefully adjusting the F/Ti molar ratio. TiO2 nanosheets smaller than 100 nm have higher photocatalytic activity and are highly stable in degradation of organic dyes.

Temperature dependence of XAFS spectra of the Perovskitetype proton conductor SrZr0.9Yb0.1O3-δ at Sr and Zr K-edges and Yb L3, L2 and L1-edges have been investigated. Chemical shifts to lower energy and change in XANES spectra are observed with increasing temperature. No change in the XANES spectra and in the threshold energies of the Yb L3-, L2- and L1-edge was observed. This indicates that the effective charges (oxidation states) of the Sr and Zr ions change with oxygen loss while the effective charge of the Yb ions were maintained. The unit cell volumes increase with increasing temperature with a slight bend between 700 and 950 K. This bend of the unit cell volumes vs. temperature is considered to be due to the loss of oxygen, which is consistent with the result of a weight loss in TGA observed in the same temperature range. The mean-square relative displacements (MSRD) of the backscattering atoms with respect to the absorbing atom were also determined by EXAFS. Its temperature dependence increases with a slight bend between 700 and 950 K, which is considered to be due to a local structure change accompanied by the loss of oxygen rather than that by the phase transition at 948 K. It is proposed that the changes of local structure and effective charges of Sr and Zr ions must play an important role in the protonic conductivity.

XAFS analysis was used to reveal local atomic environment of manganese hydroxide precipitates, the reaction products of the Winkler method which is used in the determination of dissolved oxygen in analytical chemistry. From the comparison with the XANES spectra of standard materials, it is suggested that the brown manganese, hydroxide precipitates oxidized from dissolved oxygen or H2O2 contain both divalent and trivalent ions, and are not MnO(OH)2 nor MnO2, which have been often referred as the Winkler product in general text books of analytical chemistry.

XAFS analysis was used to reveal local atomic environment of manganese in the intracellular and extracellular granules from kidney tissues in several kinds of marine bivalves. The Mn K-absorption spectra of the kidney granules were measured in a fluorescence mode. The overall spectral shapes and the positions of the Mn K-absorption edge of the kidney granules of the bivalves are similar to each other and somewhat resemble those of eosphorite (MnAl(PO4)OH)2·H2O) which contains Mn(II). These results, combined with those of IR analysis, suggest that manganese in the kidney granules exist as a phosphate with 6-fold coordination of oxygen atoms.