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Spatial resolution is a fundamental parameter in structural sciences. In crystallography, the resolution is determined from the detection limit of high-angle diffraction in reciprocal space. In electron microscopy, correlation in the Fourier domain is used for estimating the resolution. In this paper, we report a method for estimating the spatial resolution of real images from a logarithmic intensity plot in the Fourier domain. The logarithmic intensity plots of test images indicated that the full width at half maximum of a Gaussian point spread function can be estimated from the images. The spatial resolution of imaging X-ray microtomography using Fresnel zone-plate optics was also estimated with this method. A cross section of a test object visualized with the imaging microtomography indicated that square-wave patterns up to 120-nm pitch were resolved. The logarithmic intensity plot was calculated from a tomographic cross section of brain tissue. The full width at half maximum of the point spread function estimated from the plot coincided with the resolution determined from the test object. These results indicated that the logarithmic intensity plot in the Fourier domain provides an alternative measure of the spatial resolution without explicitly defining a noise criterion.

Renal toxicity is a hallmark of uranium exposure, with uranium accumulating specifically in the S3 segment of the proximal tubules causing tubular damage. As the distribution, concentration and dynamics of accumulated uranium at the cellular level is not well understood, here, we report on high-resolution quantitative in situ measurements by high-energy synchrotron radiation X-ray fluorescence analysis in renal sections from a rat model of uranium-induced acute renal toxicity. One day after subcutaneous administration of uranium acetate to male Wistar rats at a dose of 0.5 mg uranium kg(-1) body weight, uranium concentration in the S3 segment of the proximal tubules was 64.9 ± 18.2 µg g(-1) , sevenfold higher than the mean renal uranium concentration (9.7 ± 2.4 µg g(-1) ). Uranium distributed into the epithelium of the S3 segment of the proximal tubules and highly concentrated uranium (50-fold above mean renal concentration) in micro-regions was found near the nuclei. These uranium levels were maintained up to 8 days post-administration, despite more rapid reductions in mean renal concentration. Two weeks after uranium administration, damaged areas were filled with regenerating tubules and morphological signs of tissue recovery, but areas of high uranium concentration (100-fold above mean renal concentration) were still found in the epithelium of regenerating tubules. These data indicate that site-specific accumulation of uranium in micro-regions of the S3 segment of the proximal tubules and retention of uranium in concentrated areas during recovery are characteristics of uranium behavior in the kidney.

Renal toxicity is the principal health concern after uranium exposure. Children are particularly vulnerable to uranium exposure; with contact with depleted uranium in war zones or groundwater contamination the most likely exposure scenarios. To investigate renal sensitivity to uranium exposure during development, we examined uranium distribution and uranium-induced apoptosis in the kidneys of neonate (7-day-old), prepubertal (25-day-old) and adult (70-day-old) male Wistar rats. Mean renal uranium concentrations increased with both age-at-exposure and exposure level after subcutaneous administration of uranium acetate (UA) (0.1-2 mg kg(-1) body weight). Although less of the injected uranium was deposited in the kidneys of the two younger rat groups, the proportion of the peak uranium content remaining in the kidneys after 2 weeks declined with age-at-exposure, suggesting reduced clearance in younger animals. In situ high-energy synchrotron radiation X-ray fluorescence analysis revealed site-specific accumulation of uranium in the S3 segment of the proximal tubules, distributed in the inner cortex and outer stripe of the outer medulla. Apoptosis and cell loss in the proximal tubules increased with age-at-exposure to 0.5 mg kg(-1) UA. Surprisingly, prepubertal rats were uniquely sensitive to uranium-induced lethality from the higher exposure levels. Observations of increased apoptosis in generating/re-generating tubules particularly in prepubertal rats could help to explain their high mortality rate. Together, our findings suggest that age-at-exposure and exposure level are important parameters for uranium toxicity; uranium tends to persist in developing kidneys after low-level exposures, although renal toxicity is more pronounced in adults.

This paper demonstrates that high-energy SR-XRF (synchrotron radiation x-ray fluorescence spectrometry) utilizing 116 keV x-rays is a powerful technique for nondestructive discrimination of small glass fragments. An XRF spectrum of glass fragments of a standard material SRM612 gave well-resolved K-line peaks of 34 elements, including the rare-earth elements. The relative standard deviations (RSD) of the ratios of the intensities of heavy elements normalized by that of Ba were less than 8.2% for the analyses of 10 fragments (

A portable x-ray fluorescence spectrometer equipped with a silicon drift detector (SDD) and a digital signal processor (DSP) was developed for in-field analysis of archeological samples at an excavation site. This spectrometer allows us to carry out highly sensitive analyses of various elements with atomic numbers down to Na in air by using two monochromatic x-ray sources obtained by doubly bent toroidal monochromators of graphite (0002) (Pd Kα for medium–heavy elements) and PET (200) (Pd Lα for light elements) and white x-rays with a Zr filter excited at 40 kV for heavy elements. The detection limit was 0.31% for Al and 4 ppm for Sr in a standard cement sample. The spectrometer was set in a room of the excavation laboratory at al-Tūr Sinai in the Sinai Peninsula in Egypt in the summer of 2001. The Middle Eastern Culture Center has been conducting an excavation of the sites in al-Tūr al-Kilani and Rāya, which were important port cities of Red Sea trade from early Islamic periods: al-Tūr (A.D.14–20) and Rāya (A.D.8–12). The instrument was operated without any problems and 222 glass objects, 26 pottery sherds, seven pigments and 88 metallic objects were analyzed non-destructively during a 1 month stay. Since this was the first chemical analysis done at the sites, many important archaeological findings were obtained in the present study. Glass objects were successfully classified based on their chemical compositions. Characterization of stained (luster) glasses was conducted. Copyright © 2004 John Wiley & Sons, Ltd.

In spite of their superior laser and polarizer properties rare-earth orthovanadates (REVO 4 ) single crystals have not been adopted yet into extensive industrial applications because of crystal growth difficulties. The main problems of CZ technique are compositional change and diameter instability. This work presents the first attempt to apply the edge-defined film-fed growth (EFG) technique by which well-shaped REVO 4 crystals have been grown directly. The capillary properties of YVO 4 and GdVO 4 melt have been measured. The applicability of shaped growth for rare-earth orthovanadate family was approved by successful EFG growth of transparent rod-like macro-defect-free single crystals of YVO 4 and GdVO 4 . We address two main approaches to enhance the quality of EFG crystals: (i) meniscus and crystal shape stability dependence on die top shape and (ii) the strategy of effective operating control. Concave die top was found to be the best choice for high-qualit y EFG growth of REVO 4 along [001 ] direction. The spectral analysis of weight signal from growing crystal was shown to be a useful feedforward clue to prevent crystallinity degradation at a very early stage. A reasonable stability of the EFG process was achieved using [211]. [101], [001] and [100] pulling directions.

We measured the micrometer-scale fluctuation of the indium contents in a 50 μm x 30 μm region of annealed Ga0.8In0.2N/GaN multi quantum wells by mapping the counts of indium fluorescent X-rays excited by a 1.3 μm x 3.8 μm X-ray micro-beam. The mapping indicates that two distinct regions – indium-rich and indium-poor regions – are formed by the annealing. The indium contents in the island-shaped low-indium regions are 20% less than in the surrounding high-indium region. As the island-shaped low-indium regions clearly coincide with the low-radiative regions as observed by Hg-lamp-excited fluorescent microscopy, we believe that the low-radiative regions are a result not of indium segregation but of the generation of defects such as plane defects. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The automatic diameter control system was enhanced for the growth of Nd-doped GdVO 4 single crystals by the Czochralski method. It was estimated that excessive amount of feedback in the control system is the effective way to improve the shape of rare-earth vanadate single crystals. The spectral analysis for crystal weight and generator power signals was carried out in real time during growth process for determination of oscillations in the control system.

A multi-purpose analyzer was developed to carry out x-ray fluorescence (XRF) analysis of micro-samples and total reflection x-ray fluorescence (TXRF) analysis of environmental samples using either conventional x-ray or synchrotron radiation as an excitation source. Cosmic dust samples collected in Antarctica were successfully analyzed using a conventional x-ray source. XRF spectra of 36 cosmic dust samples were measured automatically using a combination of specially designed software and a sample holder, and trace amounts of heavy elements (10 ppm level in the sample) were detected. The potential ability of the XRF analyzer in TXRF mode using synchrotron x-rays from a third-generation light source, SPring-8, was tested using a standard river water and arsenic-containing water as samples. Satisfactory linearity of concentration versus net intensity of As was obtained in the concentration range 100 fg–100 ng with a detection limit of 10 fg. Copyright © 1999 John Wiley & Sons, Ltd.