シリケートの安定作用は,生物学的および合成の無形カルシウム炭酸に作用する
Assaf Gal1, Steve Weiner, Lia Addadi
1Weizmann Institute of Science, Department of Structural Biology, Rehovot 76100, Israel.
Journal of the American Chemical Society
|September 9, 2010
まとめ
シリケートイオンは,無形カルシウム炭酸 (ACC) の熱安定性を高めます. 植物シストロリットや合成サンプルで観察されるこの鉱物安定効果は,ACCがカルシットに結晶化するために必要な温度を上昇させます.
科学分野:
- 地質化学 地質化学
- マテリアルサイエンス 材料科学
- バイオミネラライゼーション
背景:
- アモルフォスカルシウム炭酸 (ACC) は,不安定な前体鉱物相である.
- 植物葉に含まれるシストロリスは,ACC形成の自然な例です.
- ACCの安定化を理解することは,材料科学とバイオミネラライゼーションの研究において極めて重要です.
研究 の 目的:
- シリケートイオンの無形カルシウム炭酸 (ACC) の熱安定性に対する影響を調査する.
- シリケートに富んだACCと,異なる植物種のシリケートに乏しいACCを比較する.
- 合成ACCサンプルに対するシリケートの安定効果を確認するために.
主な方法:
- M. alba (シリケート濃度が高い) とF. microcarpa (シリケート濃度低い) のシストロリットからのACCの比較分析.
- シリケート含有量によって異なる合成無形カルシウム炭酸塩のサンプルによるインビトロ実験.
- カルシートへの結晶化温度を決定するための熱分析.
主要な成果:
- シリケートに富んだシストロリートは,シリケートに乏しいものよりも100°C高い結晶化温度を示した.
- 合成ACCにおけるシリケート濃度の上昇は,結晶化温度上昇と直接相関しています.
- 安定化を説明するために,幾何学的挫折のメカニズムが提案されました.
結論:
- シリケートイオンは,無形カルシウム炭酸の熱安定性を大幅に高めます.
- シリケートイオンの濃度は,ACCの安定化における重要な要因である.
- シリケートイオンによる幾何学的な挫折は,ACCの結晶化をカルシートに阻害する.
関連する概念動画
01:24Hydration of Cement
Hydration of cement is a chemical reaction between cement particles and water. This process occurs primarily through two mechanisms: through-solution and topochemical. In the through-solution process, anhydrous compounds dissolve into their constituents, hydrates form in the solution, and then precipitate from the supersaturated solution. The topochemical process involves solid-state reactions at the cement particle surface. The through-solution process dominates the topochemical process at the...
04:01Factors Affecting Solubility
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Chȃtelier’s principle. Consider the dissolution of silver iodide:
01:19Ionic Strength: Effects on Chemical Equilibria
The addition of an inert ionic compound increases the solubility of a sparingly soluble salt. For example, adding potassium nitrate to a saturated solution of calcium sulfate significantly enhances the solubility of calcium sulfate. Le Châtelier's principle cannot predict this shift in the equilibrium. Instead, this could be explained in terms of changes in the effective concentration of the ions in solution in the presence of added inert salt.
In this solution, the primary cation—the calcium...
In this solution, the primary cation—the calcium...
01:26Alkali Aggregate Reaction in Concrete
The alkali-aggregate reaction in concrete involves natural siliceous minerals in aggregates reacting with alkaline hydroxides derived from cement alkalis. This reaction forms an alkali-silica gel that absorbs water, swells, and increases in volume, which is confined by the surrounding cement paste, creating internal pressures that crack and disrupt the concrete. The extent of expansion and damage can be partly attributed to the alkali-silica reaction's osmotic hydraulic pressure and the...
01:21Skeleton and Calcium Homeostasis
Calcium is not only the most abundant mineral in bone but also the most abundant mineral in the human body. Calcium ions are needed for bone mineralization, tooth health, heart rate regulation and strength of contraction, blood coagulation, the contraction of smooth and skeletal muscle cells, and the regulation of nerve impulse conduction. The average calcium level in the blood is about 10 mg/dL. When the body cannot maintain this level, a person will experience hypo or hypercalcemia.
01:18The Bone Matrix
Bone contains a relatively small number of cells entrenched in a matrix of collagen fibers that provide an adherent surface for inorganic salt crystals. Both components of the matrix, organic and inorganic, contribute to the unusual properties of bone. Without collagen, bones would be brittle and shatter easily. Without mineral crystals, bones would flex and provide little support. This can be observed by an experiment: when the minerals of a bone are dissolved by soaking the bone in acid or...