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Phosphate Deposition (phosphate + deposition)

Distribution by Scientific Domains

Polymers and Materials Science	40%

Selected Abstracts

Fabrication of Load-Bearing NiTi Scaffolds for Bone Ingrowth by Ni Foam Conversion,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Irena Gotman
Highly porous NiTi scaffolds for bone ingrowth were fabricated by reactive conversion (PIRAC) of commercially available Ni foams. These open cell ,trabecular NiTi' scaffolds possess high strength and ductility and exhibit low Ni ion release. PIRAC deposition of a thin titanium nitride (TiN) layer further improves the corrosion characteristics of "trabecular NiTi" and allows for material bioactivation by alkali treatment or biomimetic Ca phosphate deposition. [source]

The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: A comparison of serum, synovial fluid, albumin, EDTA, and water

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2006
A. C. Lewis
Abstract Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate-buffered saline (PBS), EDTA in PBS, and water were studied using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy-phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:1587,1596, 2006 [source]

RELATIONSHIP BETWEEN ORGANIC MATTER, SULPHUR AND PHOSPHATE CONTENTS IN UPPER CRETACEOUS MARINE CARBONATES (KARABOGAZ FORMATION, SE TURKEY): IMPLICATIONS FOR EARLY OIL GENERATION

JOURNAL OF PETROLEUM GEOLOGY, Issue 4 2010
S. Inan
In this paper, we discuss the relationship between the organic matter, sulphur and phosphate contents of Upper Cretaceous marine carbonates (Karabogaz Formation) in the Adiyaman Petroleum Province of SE Turkey. The results of organic geochemical analyses of core samples obtained from the Karabogaz Formation suggest that phosphate deposition occurred in settings where the water column was oxic to sub-oxic. However, the preservation of organic matter was favoured in anoxic environments. Moreover, the presence of sulphur (especially sulphur incorporated into kerogen) in organic matter-rich layers led to early oil generation. The results of stepwise py-gc analyses are consistent with a model in which, with increasing maturity, S-S and C-S bonds are the first to be eliminated from the macromolecular kerogen structure. Study of the maturity evolution of S-rich kerogen by laboratory pyrolysis implies that marginally mature and/or mature kerogen in the Karabogaz Formation, which may be classified as classic "Type II" kerogen, was most probably Type II/S at lower maturity stages. This enabled oil generation to occur at relatively shallow burial depths and relatively early stages of maturation. It is reasonable to conclude that Type II/S kerogen, overlooked in previous studies, was abundant in TOC-rich intervals in the Karabogaz Formation. Early generation (and expulsion) from Type II/S kerogen may have sourced the sulphur-rich oils in the Adiyaman area oilfields. [source]

Calcium Phosphate Crystallization on Electrospun Cellulose Non-Woven Fabrics Containing Synthetic Phosphorylated Polypeptides

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2009
Shinya Hayashi
Abstract The preparation of electrospun non-woven fabrics composed of cellulose and synthetic phosphorylated polypeptides, copoly[Ser(PO3H2)XAspY]s (X:Y,=,100:0, 75:25, 50:50, 25:75), is described. The non-wovens were subjected to an alternate immersion in CaCl2 and Na2HPO4 solutions to induce crystallization of calcium phosphate. The deposited calcium phosphate crystals were analyzed by means of EDX analysis and WXRD. The amounts of calcium phosphate deposition are greater for the cellulose non-woven fabrics containing copoly[Ser(PO3H2)XAspY] than those of cellulose-only non-woven fabrics. These results indicate that copoly[Ser(PO3H2)XAspY] can entrap Ca2+ ions around the fine fiber matrix to accelerate crystallization of the calcium phosphate. [source]

Expression of osteopontin messenger RNA by macrophages in ovarian serous papillary cystadenocarcinoma: A possible association with calcification of psammoma bodies

PATHOLOGY INTERNATIONAL, Issue 7 2000
Masahiko Maki
Calcified psammoma bodies often appear in human ovarian serous papillary cystadenocarcinoma. Osteocalcin (OC), osteonectin (ON) and osteopontin (OPN) are three members of non-collagenous bone-related proteins known to be related with mineralization of bone. To clarify possible involvement of these bone matrix proteins in the calcification of the psammoma bodies, the expression of OC, ON and OPN was analyzed by immunohistochemical and in situ hybridization studies using 15 surgical specimens. OPN protein was detected in the calcified area of the psammoma bodies which was positively stained by von Kóssa's staining, while OC and ON proteins were not. OPN protein was not detected in any cells in tissues, but OPN messenger ribonucleic acid (mRNA) was detected in CD68-positive macrophages, indicating that OPN was produced and promptly secreted by macrophages. These results suggest that OPN produced and promptly secreted by macrophages and subsequently translocated to psammoma bodies may be causally related with the calcium phosphate deposition in the psammoma bodies of the ovarian serous papillary cystadenocarcinomas. [source]