Speciation and quantitative mapping of metal species in microbial biofilms using scanning transmission X-ray microscopy

A scanning transmission X-ray microscope illuminated with synchrotron light was used to investigate the speciation and spatial distributions of metals in a microbial biofilm cultivated from river water. Metal 2p absorption edge signals were used to provide metal speciation (through shapes of the absorption spectra) and quantitative spatial distributions of the metal species. This paper presents sample data and describes methods for extracting quantitative maps of metal species from image sequences recorded in the region of the metal 2p edges. Comparisons were made with biochemical characterization of the same region using images recorded at the C 1s and O 1s edges. The method is applied to detailed quantitative analysis of ferrous and ferric iron in a river biofilm, in concert with mapping Ni(II) and Mn(II) species in the same region. The distributions of the metal species are discussed in the context of the biofilm structure. These results demonstrate that soft X-ray STXM measurements at the metal 2p absorption edges can be used to speciate metals and to provide quantitative spatial distribution maps for metal species in environmental samples with 50 nm spatial resolution.     

Clear P-wave arrival of weak events and automatic onset determination using wavelet filter banks

P-wave arrivals of many weak events cannot be precisely determined manually. Difference in power levels between noise and P-wave in wavelet detail of weak events enables us to determine P-wave arrival manually. Because of this power difference, automatic onset detection and picking algorithm is introduced using the same wavelet detail. Parameter settings are not needed as algorithm will work on data generated by either short or very broad band seismometers. Application of the proposed algorithm on data of three stations of Egyptian National Seismic Network (ENSN) in Cairo region shows a maximum standard deviation of 0.14 seconds of the corresponding manual picks.     

Kooroo color: 90-day dietary toxicity study in F344 rats

A subchronic toxicity study on kooroo color was conducted using F344 rats of both genders. Kooroo color is an extract of yam root, Dioscorea matudai Hayata, of which the major components are known to be flavonoid pigments. Use of kooroo as a food color is permitted by the Food Sanitation Law in Japan, but the chronic toxicity has not been evaluated in the literature. Rats were fed the product of kooroo color (PKC) at doses of 0.5%, 1.50%, and 5.0% in basal powder diet, while control groups received PKC-free basal diet, for ninety days. A vehicle control given propylene glycol (PG) alone, at the same dosage that the 5.0% group received, was included, because PKC used in this study contained ca. 80 percent PG, used as an extractant during the manufacturing processes. Daily observation of general behavior, and weekly measurement of body weight as well as food consumption were performed. Hematological, serum biochemical and anatomopathological examinations were conducted at the end of administration. No abnormalities ascribable to the treatment with PKC or PG were noted in any examination in this study. Hence, dietary intake of 5.0% of PKC, i.e., 2,993 mg/kg/day for males, and 3,376 mg/kg/day for females, as a mean daily intake for 90 days, had no observable adverse effect in F344 rats. Therefore, kooroo color has no significant general toxicity, and its toxicity, if any, is of a very low order.     

Phase Transitions of Superfluid 3He in 0.8-μm Slab Geometry

We have studied superfluid ³ He in 0.8 m slab geometry by cw-NMR method. The static magnetic field for NMR was 22 mT and was perpendicularly applied to the surface. At pressures from 5 bar to 27 bar, we observed the negative shifts of NMR frequencies below the transition temperatures. Moreover we observed the fast order phase transition with the supercooling phenomena at lower temperatures, but NMR frequencies did not show a jump as they do at the A-B transition in the bulk liquid. Although the phase at low temperatures seemed to be B-phase, NMR frequencies still had the negative shifts.     

A direct nanoflow liquid chromatography-tandem mass spectrometry system for interaction proteomics

One of the strategies of functional proteomics, research aiming to discover gene function at the protein level, is the comprehensive analysis of protein-protein interactions related to the functional linkage among proteins and analysis of functional cellular machinery to better understand the basis of cell functions. Here, we describe the direct nanoflow LC (DNLC) system, which is equipped with a fritless high-resolution electrospray interface column packed with 1-microm reversed-phase (RP) beads and a novel splitless nanoflow gradient elution system to operate the column. Using RP-DNLC at an extremely slow flow rate, <50 nL/min, combined with data-dependent collision-induced dissociation tandem MS (MS/MS) and computer-assisted retrieval of spectra, we identified approximately 100 protein components in a biological complex such as a premature mammalian ribosome pull-down from cultured cells when we used an epitope-tagged protein as bait. Because this analysis is most sensitive, requires approximately 0.2 microg of total protein, and is a fully automated 1-h process, we anticipated that it should be an excellent tool for analyzing a limited amount of functional multi-protein complexes in cells.     

Reconstruction of an object from its Fourier modulus: development of the combination algorithm composed of the hybrid input-output algorithm and its converging part

The hybrid input-output algorithm (HIO) used for phase retrieval is in many cases combined with the error-reduction algorithm (ER) to attempt to stabilize the HIO. However, in our previous paper [J. Opt. Soc. Am. A 16, 2163 (1999)], it was demonstrated that this combination makes it more likely that the resultant algorithm will fall into a periodic state before reaching a solution because the values of the input object outside the support, which is imposed as the object-domain constraint, are set to be zero in the intervals in which the ER is implemented. This paper deals with this problem inherent in the combination algorithm. The converging part of the HIO (CPHIO), which is an algorithm we previously developed [J. Opt. Soc. Am. A 15, 2849 (1998)], can be thought of as an extension of the ER for the case in which the input object can have nonzero values outside the support. Keeping this in mind, the algorithm is then constructed by combining the HIO with the CPHIO instead of with the ER. The computer simulation results that demonstrate the effectiveness of the proposed algorithm are given.     

Mechanical and magnetic properties of nickel-dispersed tetragonal zirconia nanocomposites

Effects of Ni dispersions on microstructure and mechanical properties have been studied for Y2O3-stabilized tetragonal zirconia (Y-TZP)/Ni nanocomposites with Ni dispersion up to 10 vol%. Composites were successfully fabricated by reducing and hot-pressing Y-TZP/NiO powder mixtures. Fracture strength was significantly improved from 1.5 GPa for monolithic Y-TZP to 1.9 GPa for nanocomposites with a small addition of Ni (1-2 vol%). Magnetic properties of Y-TZP/Ni nanocomposites were also investigated. Magnetization curves of Y-TZP/Ni nanocomposites showed typical hysteresis loops of soft magnetic materials, whereas coercivity was much larger than that of pure Ni metal. A new function arising from magnetomechanical effects of metallic Ni is also discussed for the present nanocomposites.