scholarly journals Strong Stabilization of Amorphous Calcium Carbonate Emulsion by Ovalbumin: Gaining Insight into the Mechanism of ‘Polymer-Induced Liquid Precursor’ Processes

2011 ◽  
Vol 133 (32) ◽  
pp. 12642-12649 ◽  
Author(s):  
Stephan E. Wolf ◽  
Jork Leiterer ◽  
Vitaliy Pipich ◽  
Raul Barrea ◽  
Franziska Emmerling ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Amorphous Calcium Carbonate ◽  
Liquid Precursor ◽  
Strong Stabilization ◽  
Insight Into ◽  
Gaining Insight

scholarly journals Strong stabilization of liquid amorphous calcium carbonate by polymers and proteins

2014 ◽  
Vol 70 (a1) ◽  
pp. C594-C594
Author(s):  
Filipe Natalio ◽  
Tomas Corrales ◽  
Michael Dietzsch ◽  
Ingo Lieberwirth ◽  
Enrico Mugnaioli ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Self Assembly ◽  
Bending Strength ◽  
The Self ◽  
Elastic Response ◽  
Electron Crystallography ◽  
Amorphous Calcium Carbonate ◽  
Liquid Precursor ◽  
Strong Stabilization ◽  
Egg Shell

We have studied the effect of bio-inspired polymers and proteins like ovalbumin, lysozyme and silicatein, which are present in the first stage of egg shell formation or in the formation of siliceous spicules of sponges, on the homogeneous formation of the liquid-amorphous calcium carbonate (LACC) precursor, by a combination of complementary methods like in situ WAXS, light scattering, TEM and cryo-TEM. Lysozyme destabilizes the LACC emulsion, whereas ovalbumin extends the lifetime of the emulsified state. We demonstrate that ovalbumin acts as a stabilizer for a polymer-induced liquid precursor (PILP) process. We propose that the liquid amorphous calcium carbonate is affected by polymers by depletion stabilization and de-emulsification rather than induced by acidic proteins and polymers during a polymer-induced liquid precursor process. Thus, the original PILP coating effect appears to be a result of a de-emulsification process of a stabilized LACC phase. Silicatein-α is responsible for the biomineralization of silica in sponges guides the self-assembly of calcite "spicules" similar to the spicules of the calcareous sponge Sycon. The self-assembled spicules, 10-300 µm in length and 5-10 µm in diameter, are composed of aligned calcite nanocrystals. The spicules are initially amorphous but transform into calcite within months, exhibiting unusual growth along [100]. While natural spicules evidence brittle failure, the synthetic spicules show an elastic response which greatly enhances bending strength. Later stages of nucleation have been studied by "trapping" nuclei from solution by shock-freezing of droplets in liquid ethane (cryo-TEM). This yields snapshots of the structure formation process at given point. In a first step the full determination of the structure of vaterite, one of the common CaCO3 polymorphs, was solved on nanometer-sized crystallites by electron crystallography. These results demonstrate that crystals that are too small for single-crystal X-ray diffraction and too difficult to solve by powder diffraction may nevertheless be amenable to accurate structure determination by electron crystallography.

scholarly journals Using simulation to understand the structure and properties of hydrated amorphous calcium carbonate

CrystEngComm ◽  
2016 ◽  
Vol 18 (1) ◽  
pp. 92-101 ◽  
Author(s):  
Riccardo Innocenti Malini ◽  
Yuriy G. Bushuev ◽  
Shaun A. Hall ◽  
Colin L. Freeman ◽  
P. Mark Rodger ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Structure And Properties ◽  
Amorphous Calcium Carbonate ◽  
Insight Into

The protocols used give a range of behaviours comparable to previous experiments and an insight into the structure of ACC.

Standing up to the Demos

2018 ◽  
Author(s):  
Andrew Erskine
Keyword(s):  
Athenian Democracy ◽  
Parallel Lives ◽  
Standing Up ◽  
A Minor ◽  
Insight Into ◽  
Gaining Insight ◽  
The Way

Plutarch wrote twenty-three Greek Lives in his series of Parallel Lives—of these, ten were devoted to Athenians. Since Plutarch shared the hostile view of democracy of Polybius and other Hellenistic Greeks, this Athenian preponderance could have been a problem for him. But Plutarch uses these men’s handling of the democracy and especially the demos as a way of gaining insight into the character and capability of his protagonists. This chapter reviews Plutarch’s attitude to Athenian democracy and examines the way a statesman’s character is illuminated by his interaction with the demos. It also considers what it was about Phocion that so appealed to Plutarch, first by looking at his relationship with the democracy and then at the way he evokes the memory of Socrates. For him this was not a minor figure, but a man whose life was representative of the problems of Athenian democracy.

scholarly journals Pure hydroxyapatite synthesis originating from amorphous calcium carbonate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michika Sawada ◽  
Kandi Sridhar ◽  
Yasuharu Kanda ◽  
Shinya Yamanaka
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Room Temperature ◽  
Molar Ratio ◽  
Final Phase ◽  
Amorphous Calcium Carbonate ◽  
Phosphate Compound ◽  
Synthesis Strategy ◽  
Phosphorylation Reaction ◽  
Subsequent Calcination

AbstractWe report a synthesis strategy for pure hydroxyapatite (HAp) using an amorphous calcium carbonate (ACC) colloid as the starting source. Room-temperature phosphorylation and subsequent calcination produce pure HAp via intermediate amorphous calcium phosphate (ACP). The pre-calcined sample undergoes a competitive transformation from ACC to ACP and crystalline calcium carbonate. The water content, ACC concentration, Ca/P molar ratio, and pH during the phosphorylation reaction play crucial roles in the final phase of the crystalline phosphate compound. Pure HAp is formed after ACP is transformed from ACC at a low concentration (1 wt%) of ACC colloid (1.71 < Ca/P < 1.88), whereas Ca/P = 1.51 leads to pure β-tricalcium phosphate. The ACP phases are precursors for calcium phosphate compounds and may determine the final crystalline phase.

scholarly journals Gaining Insight into Vitiligo Genetics through the Lens of a Large Epidemiologic Study

2021 ◽  
Vol 141 (4) ◽  
pp. 718-721
Author(s):  
Ken Okamura ◽  
Manuel Garber ◽  
John E. Harris
Keyword(s):  
Epidemiologic Study ◽  
Insight Into ◽  
Gaining Insight

scholarly journals On the Relation of Amorphous Calcium Carbonate and the Macromechanical Properties of Sea Urchin Spines

2020 ◽  
Vol 22 (4) ◽  
pp. 1900922 ◽  
Author(s):  
Christoph Lauer ◽  
Sebastian Haußmann ◽  
Patrick Schmidt ◽  
Carolin Fischer ◽  
Doreen Rapp ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Sea Urchin ◽  
Amorphous Calcium Carbonate ◽  
Sea Urchin Spines

scholarly journals Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule

2008 ◽  
Vol 105 (45) ◽  
pp. 17362-17366 ◽  
Author(s):  
Y. Politi ◽  
R. A. Metzler ◽  
M. Abrecht ◽  
B. Gilbert ◽  
F. H. Wilt ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Sea Urchin ◽  
Amorphous Calcium Carbonate ◽  
Transformation Mechanism
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