Neutralization of Acidic Sulfur Species by Calcite in Mineral Aerosols Collected in China and Japan Studied by Ca K-Edge X-Ray Absorption Near-Edge Structure Spectroscopy X-ray absorption near-edge structure studies at the calcium K-edge have been used to show that acidic sulfur species in the atmosphere (e.g., H2SO4), mainly released by human activities, can be neutralized by the calcite prese...

We demonstrate a correlation between how an IR-active vibrational mode responds to temperature changes and how it responds to crystallinity differences. Infrared (IR) spectroscopy was used to track changes in carbonate-related vibrational modes in three different CaCO3 polymorphs (calcite, aragonite, and vaterite) and CaMg(CO3)2 (dolomite) during heating. Of the three characteristic IR-active c...

The term mesocrystal has been widely used to describe crystals that form by oriented assembly, and that exhibit nanoparticle substructures. Using calcite crystals co-precipitated with polymers as a suitable test case, this article looks critically at the concept of mesocrystals. Here we demonstrate that the data commonly used to assign mesocrystal structure may be frequently misinterpreted, and...

A calcite-rich block in nephelinitic agglomerate at Oldoinyo Lengai comprises Sr-calcite, apatite, fluorite, a Ba-Mn oxide akin to romanrchite, and a distinctive Mn-Fe spinel. Formerly reported as sC3vite, on textural, mineralogical and stable isotope grounds it is now re-interpreted as a highly-altered natrocarbonatite lava. An implication of this study is that natrocarbonatite is not just a m...

BACKGROUND Studies have demonstrated that carbonic anhydrase I (CA1) stimulates calcium salt precipitation and cell calcification, which is an essential step in new bone formation. Our study had reported that CA1 encoding gene has a strong association with rheumatoid arthritis (RA) and ankylosing spondylitis (AS), two rheumatic diseases with abnormal new bone formation and bone resorption in jo...

Ipsilateral and contralateral hippocampal CA3-CA1 and CA2-CA1 projections were investigated in adult male Long-Evans rats by retrograde tracing. Injection of the retrograde tracer cholera toxin subunit B in the strata oriens and radiatum of dorsal CA1 resulted in labeling of predominantly pyramidal cells in ipsilateral and contralateral CA3 and CA2. The contralateral and ipsilateral anterior-po...

Fast pyrolysis of rice husk was performed in a spout-fluid bed to produce water-soluble organics. The effects of mineral bed materials (red brick, calcite, limestone, and dolomite) on yield and quality of organics were evaluated with the help of principal component analysis (PCA). Compared to quartz sand, red brick, limestone, and dolomite increased the yield of the water-soluble organics by 6-...

A new type of composite 3D biomaterial that provides extracellular cues that govern the differentiation processes of mesenchymal stem cells (MSCs) has been developed. In the present study, we evaluated the chondrogenecity of a biohybrid composed of a calcium carbonate scaffold in its calcite polymorph and hyaluronic acid (HA). The source of the calcite scaffolding is an exoskeleton of a sea bar...

Hierarchical composite materials design in biological exoskeletons achieves penetration resistance through a variety of energy-dissipating mechanisms while simultaneously balancing the need for damage localization to avoid compromising the mechanical integrity of the entire structure and to maintain multi-hit capability. Here, we show that the shell of the bivalve Placuna placenta (~99 wt% calc...

Textures of calcite crystals from a variety of mineralized tissues belonging to organisms from four phyla were examined with high-resolution synchrotron x-ray radiation. Significant differences in coherence length and angular spread were observed between taxonomic groups. Crystals from polycrystalline skeletal ensembles were more perfect than those that function as single-crystal elements. Diff...