Video Experimental Relacionado
Updated: Jul 10, 2026
08:46
Determining the Ice-binding Planes of Antifreeze Proteins by Fluorescence-based Ice Plane Affinity
Published on: January 15, 2014
Estudios estructurales de varias formas distintas y metastables de hielo amorfo
C A Tulk1, C J Benmore, J Urquidi
1Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Science (New York, N.Y.)
|August 24, 2002
Resumen
El recocido del hielo amorfo de alta densidad revela una compleja serie de formas estructurales intermedias. Estos hallazgos sugieren que las transformaciones de fase de agua líquida a baja temperatura son más intrincadas de lo que se entendía anteriormente.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física de la materia condensada Física de la materia condensada
- Química Física es la química física.
Sus antecedentes:
- El hielo amorfo, particularmente el hielo amorfo de alta densidad (HDA), es un sistema modelo crucial para comprender las propiedades del agua.
- Estudios anteriores han sugerido la existencia de diferentes fases de agua amorfa, pero las transiciones estructurales entre ellas siguen siendo poco conocidas.
Objetivo del estudio:
- Para investigar la evolución estructural del hielo amorfo de alta densidad durante el recocido.
- Identificar y caracterizar las fases amorfas intermedias formadas durante la transformación al hielo amorfo de baja densidad (LDA).
- Para obtener información sobre el complejo comportamiento de fase del agua a bajas temperaturas.
Principales métodos:
- La difracción de neutrones y la difracción de rayos X se emplearon para sondear la estructura atómica.
- El primer pico de difracción fue monitoreado sistemáticamente a través de un rango de temperaturas de recocido.
- Se calcularon las funciones de distribución radial para analizar los cambios estructurales.
Principales resultados:
- Las transiciones estructurales del hielo HDA al hielo LDA ocurren a través de una serie de formas intermedias amorfas distintas y metastables.
- Se identificaron y caracterizaron cinco fases amorfas específicas utilizando la dispersión de neutrones.
- Se observó una evolución estructural sistemática en las funciones de distribución radial entre 4 y 8 angstroms.
Conclusiones:
- El recocido del hielo amorfo implica una vía compleja con múltiples estados intermedios.
- Las transformaciones de fase en el agua de baja temperatura son significativamente más complejas de lo que sugieren los modelos actuales.
- Se necesita más investigación para dilucidar completamente las diversas fases amorfas del agua.
Videos de Conceptos Relacionados
01:23States of Water
Water exists in any one of the three classical states: solid (ice), liquid (water), and gas (steam or water vapor). The state of water depends on i) the intermolecular forces that draw molecules together and ii) the kinetic energy that leads to movements that pull them apart.
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
02:39Phase 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...
02:22Structures of Solids
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
01:18Indeterminate Structure
Indeterminate structures refer to structures where internal forces and reactions cannot be determined using only the equations of static equilibrium. Indeterminate structures have more unknown forces and reaction forces than equations of static equilibrium that can be used to determine them. Indeterminate structures are often used in engineering to create complex, efficient, and aesthetically pleasing structures. There are various types of indeterminate structures used in engineering and some...
01:14Stability of structures
In mechanical engineering, the stability of systems under various forces is critical for designing durable and efficient structures. One fundamental way to explore these concepts is by analyzing systems like two rods connected at a pivot point, O, with a torsional spring of spring constant k at the pivot point. This system is similar in appearance to a scissor jack used to change tires on a car. In this case, the arms of the linkage (equivalent to the rods in this system) are entirely vertical,...
01:27Frost 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...