Introduction: The Mars Phoenix Scout Mission with its diverse instrument suite successfully examined several soils on the Northern plains of Mars. The Thermal and Evolved Gas Analyzer (TEGA) was employed to detect organic and inorganic materials by coupling a differential scanning calorimeter (DSC) with a magnetic-sector mass spectrometer (MS). Martian soil was heated up to 1000°C in the DSC ov...

Ž . This paper documents possible modern within the last 50 years calcite cementation within an unconfined contaminated Ž . aquifer at the Test Area North TAN on the Idaho National Engineering and Environmental Laboratory site. Inferred modern calcite occurs at the distal tips of the latest generation of calcite cement and has bright luminescence when examined Ž . by cathodoluminescence. Lumine...

-By combining synchrotron X-ray standing wave (XSW) measurements with synchrotron Xray reflectivity measurements, we have determined: (1) the precise three-dimensional location within the calcite unit cell of submonolayer Pb ions adsorbed at the calcite (104) surface from dilute aqueous solutions, and (2) the precise one-dimensional location of these unit cells relative to the calcite surface. ...

The role of microbial urease in calcite precipitation was studied utilizing a recombinant Escherichia coli HB101 containing a plasmid, pBU11, that encodes Bacillus pasteurii urease. The calcite precipitation by E. coli HB101 (pBU11) was significant although its precipitation level was not as high as that by B. pasteurii. Addition of low concentrations (5-100 microM) of nickel, the cofactor of u...

In order to obtain hydrophobic material, the water suspension of natural limestone with the high content of calcite (>95 %), was treated with different amounts (0.5-4 %) of stearic acid dissolved in chloroform. Thermal analysis showed that at lower initial concentrations of stearic acid (up to 2 %), surfactant molecules are chemisorbed on calcite surface, while at higher initial concentrations ...

Biominerals, especially molluscan shells, generally contain unusually acidic proteins. These proteins are believed to function in crystal nucleation and inhibition. We previously identified an unusually acidic protein Aspein from the pearl oyster Pinctada fucata. Here we show that Aspein can control the CaCO(3) polymorph (calcite/aragonite) in vitro. While aragonite is preferentially formed in ...

chromate conversion coating is applied on aluminum 6061. the optimum conditions for chromate bath composition and immersion time are also obtained for standard requirements provision such as corrosion resistance in salt spray test, electrical resistance and coating quality. the applied coatings are electrochemically tested in sea and distilled water. according to tafel and cyclic polarization c...

Plitvice Lakes waters were collected at 14 sampling points, including springs, tributaries and lakes, for the period 2002-2007. The results of the physical and chemical conditions of calcite precipitation as well as the δ(13)C values of dissolved inorganic carbon (DIC) were used to study the processes influencing calcite precipitation. Significant differences between spring, lake and stream wat...

Carbon isotopes in speleothems can vary in response to a number of complex processes active in cave systems that are both directly and indirectly related to climate. Progressing downward from the soil zone overlying the cave, these processes include soil respiration, fluid–rock interaction in the host limestone, degassing of CO2 and precipitation of calcite upflow from the speleothem drip site,...

A thin (3–25 cm), persistent conglomerate-sandstone unit occurs at the base of the transgressive systems tract of an Upper Pennsylvanian cyclothem below a transgressive limestone in outcrop and subsurface in SE Kansas and NE Oklahoma. It has an erosional base and a sharp top, and is composed of calcitic clasts, some shell fragments and quartz sand, and rare coal fragments. Clasts are rounded, e...