関連する実験動画
Updated: Jul 12, 2026

08:00
Freezing Human ES Cells
Published on: October 12, 2006
まとめ
凍結に関する新しい近似理論である密度関数理論は,古典的な液体の正確な予測を提供します. このアプローチは結晶化の理解を簡素化し,複雑な動的現象理論の基礎となる.
科学分野:
- 熱力学は熱力学である.
- 材料科学 材料科学とは
- 統計力学 統計力学とは
背景:
- 凍結と融解のプロセスの基本的な理解は,単純な材料でさえ,欠けている.
- 段階図を予測することは,結晶-溶融界面,ほぼ均衡の結晶化,および核形成現象の理解に不可欠です.
研究 の 目的:
- 古典的な液体の冷凍に関する新しい近似理論を導入し,評価する.
- 数学的にシンプルで正確なモデルを提供することによって,より複雑な理論のための基礎を確立する.
主な方法:
- 新しく開発された密度関数理論 (DFT) を凍結に適用する.
- DFTアプローチの予測精度と数学的な単純さの分析.
主要な成果:
- 密度関数理論は,古典的な液体の凍結について比較的正確な予測を提供します.
- この理論の数学的な構造は,さらに発展させるのに十分なほど単純である.
結論:
- 密度関数理論は,液体-固体相変遷のモデリングにおける重要な進歩を表しています.
- その正確さと単純さは,材料科学におけるより複雑な動的現象を調査するための貴重な出発点となっています.
関連する概念動画
Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
Freezing Point Depression and Boiling Point Elevation
Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
Freezing Point Depression and Boiling Point Elevation
When a non-volatile solute is added to a pure solvent, it results in the lowering of the freezing point of the solvent. This phenomenon is called freezing point depression. The extent to which the freezing point is lowered depends on the molality of the solute -the number of moles of solute per kilogram of solvent and the cryoscopic constant of the solvent.From the plot of chemical potential, μ, against temperature, it is evident that the μ of both solid and liquid solvents decrease with...
Decreased Body Temperature
A decreased body temperature can occur in patients with hypothermia and frostbite. Heat loss with extended cold exposure overpowers the body's ability to create heat, resulting in hypothermia. Core temperature readings help classify hypothermia. Mild hypothermia is temperatures between 32 °C (89.6 °F) and 35°C (95 °F) and is caused by impaired thermoregulation. Moderate hypothermia is temperatures between 28 C (82.4 °F) and 32 °C (89.6 °F) caused by sustained extreme cold exposure, and severe...
Frost Action on Concrete
Concrete structures in cold climates, such as those along roadsides, can retain moisture. This moisture makes them susceptible to frost-related damage when temperatures fall below freezing. Adding moisture worsens the damage during temperature fluctuations, leading to repeated freezing and thawing. De-icing salts, spread over these structures to melt ice, add to the freeze-thaw cycle, and draw even more moisture into the concrete.
This freeze-thaw cycle primarily causes surface scaling, where...
This freeze-thaw cycle primarily causes surface scaling, where...
Cryo-electron Microscopy
Conventional electron microscopy (EM) involves dehydration, fixation, and staining of biological samples, which distorts the native state of biological molecules and results in several artifacts. Also, the high-energy electron beam damages the sample and makes it difficult to obtain high-resolution images. These issues can be addressed using cryo-EM, which uses frozen samples and gentler electron beams. The technique was developed by Jacques Dubochet, Joachim Frank, and Richard Henderson, for...

