Improved image contrast of calcifications in breast tissue specimens using diffraction enhanced imaging.

The contrast of calcifications in images of breast tissue specimens using a synchrotron-based diffraction enhanced imaging (DEI) apparatus has been measured and is compared to the contrast in images acquired using a conventional synchrotron-based radiographic imaging modality. DEI is an imaging modality which derives image contrast from x-ray absorption, refraction and small-angle scatter-rejection (extinction), unlike conventional radiographic techniques, which can only derive contrast from absorption. DEI is accomplished by inserting an analyser crystal in the beam path between the sample and the detector.

In situ studies of metal-semiconductor interactions with synchrotron radiation.

The capabilities and performance of a UHV system for in situ studies of metal-semiconductor interactions are described. The UHV system consists of interconnected deposition and analysis chambers, each of which is capable of maintaining a base pressure of approximately 1 x 10(-10) torr. The deposited materials and their reaction products can be studied in situ with RHEED, XAFS, AES, XPS, UPS and ARUPS.

Speciation of phosphorus in phosphorus-enriched agricultural soils using X-ray absorption near-edge structure spectroscopy and chemical fractionation.

Knowledge of phosphorus (P) species in P-rich soils is useful for assessing P mobility and potential transfer to ground water and surface waters. Soil P was studied using synchrotron X-ray absorption near-edge structure (XANES) spectroscopy (a nondestructive chemical-speciation technique) and sequential chemical fractionation. The objective was to determine the chemical speciation of P in long-term-fertilized, P-rich soils differing in pH, clay, and organic matter contents.

Measurement of image contrast using diffraction enhanced imaging.

Refraction contrast of simple objects obtained using diffraction enhanced imaging (DEI) was studied and compared to conventional radiographic contrast. Lucite cylinders and nylon wires were imaged using monochromatic synchrotron radiation at the National Synchrotron Light Source (http://nslsweb. nsls.

Formation of chloropyromorphite in a lead-contaminated soil amended with hydroxyapatite.

Conversion of soil Pb to pyromorphite [Pb5(PO4)3Cl] was evaluated by reacting a Pb contaminated soil collected adjacent to a historical smelter with hydroxyapatite [Ca5(PO4)3OH]. In a dialysis experiment where the soil and hydroxyapatite solids were placed in separate dialysis bags suspended in 0.01 M NaNO3 solution a crystalline precipitate, identified as chloropyromorphite, formed on the dialysis membrane containing the soil.

XAFS studies of the formation of cobalt silicide on (square root of 3 x square root of 3) SiC(0001).

Thin Co films (1-8 nm) were directly, sequentially, and co-deposited with Si (3.6-29.2 nm) on the (square root of 3 x square root of 3)-R30 degrees reconstruction of 6H-SiC(0001).

Bonding of Hg(II) to reduced organic sulfur in humic acid as affected by S/Hg ratio.

Organic matter is an important sorbent of heavy metals in soils and sediments. The heterogeneity of organic matter, including the presence of various reactive O-, N-, and S-bearing ligands, makes it difficult to precisely characterize the nature of metal-ligand binding sites. The objective of this research was to characterize the extent and nature of Hg(II) bonding with reduced organic S in soil organic matter.

Human breast cancer specimens: diffraction-enhanced imaging with histologic correlation--improved conspicuity of lesion detail compared with digital radiography.

Seven breast cancer specimens were examined with diffraction-enhanced imaging at 18 keV with a silicon crystal with use of the silicon 333 reflection in Bragg mode. Images were compared with digital radiographs of the specimen, and regions of increased detail were identified. Six of the seven cases (86%) showed enhanced visibility of surface spiculation that correlated with histopathologic information, including extension of tumor into surrounding tissue.

Formation of the ferritin iron mineral occurs in plastids.

Ferritin in plants is a nuclear-encoded, multisubunit protein found in plastids; an N-terminal transit peptide targets the protein to the plastid, but the site for formation of the ferritin Fe mineral is unknown. In biology, ferritin is required to concentrate Fe to levels needed by cells (approximately 10(-7) M), far above the solubility of the free ion (10(-18) M); the protein directs the reversible phase transition of the hydrated metal ion in solution to hydrated Fe-oxo mineral. Low phosphate characterizes the solid-phase Fe mineral in the center of ferritin of the cytosolic animal ferritin, but high phosphate is the hallmark of Fe mineral in prokaryotic ferritin and plant (pea [Pisum sativum L.

The recharacterization of a polysaccharide iron complex (Niferex).

An oral hematinic marketed as "Niferex," the active component of which is a polysaccharide-iron complex (PIC), has recently been recharacterized. PIC is synthesized by the neutralization of an FeCl3 carbohydrate solution. Original characterization of this complex by Mössbauer spectroscopy and X-ray powder diffraction suggested that the iron-rich core was similar in structure to the mineral ferrihydrite.

Iron environment in ferritin with large amounts of phosphate, from Azotobacter vinelandii and horse spleen, analyzed using extended X-ray absorption fine structure (EXAFS).

The iron core of proteins in the ferritin family displays structural variations that include phosphate content as well as the number and the degree of ordering of the iron atoms. Earlier studies had shown that ferritin iron cores naturally high in phosphate, e.g.

Rapid reduction of iron in horse spleen ferritin by thioglycolic acid measured by dispersive X-ray absorption spectroscopy.

The release of iron from ferritin is important in the formation of iron proteins and for the management of diseases in both animals and plants associated with abnormal accumulations of ferritin iron. Much more iron can be released experimentally by reduction of the ferric hydrous oxide core than by chelation of Fe3+ which has led to the notion that reduction is also the major aspect of iron release in vivo. Variations in the kinetics of reduction of the mineral core of ferritin have been attributed to the redox potential of the reductant, redox properties of the iron core, the structure of the protein coat, the analytical method used to detect Fe2+ and reactions at the surface of the mineral.