零温度干扰过渡的热残留物
Zexin Zhang1, Ning Xu, Daniel T N Chen
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. zexin@sas.upenn.edu
Nature
|May 16, 2009
概括
研究人员探索了粒子干扰过渡在更高温度下如何表现. 他们发现,来自零温度阻塞的关键长度尺度在热系统中持续存在,为颗粒材料和泡提供了新的见解.
科学领域:
- 物理 物理学 物理
- 材料科学 材料科学 材料科学
- 软物质物理学 软物质物理学
背景情况:
- 在颗粒材料和泡中,当加大包装分数导致刚性时,会发生堵塞过渡.
- 在零温度 (T = 0) 时,分离和消失的长度尺度标志着干扰过渡.
- 热运动会影响小粒子的阻塞,因此需要研究超出T = 0极限.
研究的目的:
- 为了研究随着温度的增加,与干扰相关的长度尺度的演变.
- 为了确定T = 0干扰过渡特征是否在热系统中持续存在.
- 作为一个关键参数,跟踪邻近粒子之间的重叠距离.
主要方法:
- 使用了合体实验.
- 使用计算机模拟.
- 聚焦在邻近粒子之间的重叠距离上.
主要成果:
- 观察到重叠距离保留了其T = 0行为的遗迹.
- 发现这种结构特征以一种不寻常的方式进化.
- 证明了重叠距离是显而易见的,作为固定温度的包装分量的函数,而不是相反.
结论:
- 与T = 0干扰过渡相关的长度尺度在热系统中仍然存在.
- 这些发现在模拟和实验室实验中都是有效的.
- 叠加距离的不寻常演变以前掩盖了它的外观.
相关概念视频
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...
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...
Zeroth Law of Thermodynamics
Experimentally, if object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is in equilibrium with object C. That statement of transitivity is called the "zeroth law of thermodynamics." For example, a cold metal block and a hot metal block are both placed on a metal plate at room temperature. Eventually, the cold block and the plate will be in thermal equilibrium. In addition, the hot block and the plate will be in thermal equilibrium. By the zeroth...
The Zeroth Law of Thermodynamics
Systems in mechanical equilibrium exert equal pressure on the separating wall. Similarly, systems in thermal equilibrium share a common thermodynamic property: temperature.Temperature is a measure of the average kinetic energy of particles within a system. More generally, it reflects the internal energy state of the system. The higher the temperature, the more energy a system has, given that other variables, such as volume and pressure, remain constant. However, temperature is not a form of...
Thermosensation
Peripheral thermosensation is the perception of external temperature. A change in temperature (on the surface of the skin and other tissues) is detected by a family of temperature-sensitive ion channels called Transient Receptor Potential, or TRP, receptors. These receptors are located on free nerve endings. Those detecting cold temperatures are closer to the surface of the skin than the nerve endings detecting warmth. These thermoTRP channels, while temperature selective, have relatively...
Effects of Temperature on Free Energy
The spontaneity of a process depends upon the temperature of the system. Phase transitions, for example, will proceed spontaneously in one direction or the other depending upon the temperature of the substance in question. Likewise, some chemical reactions can also exhibit temperature-dependent spontaneities. To illustrate this concept, the equation relating free energy change to the enthalpy and entropy changes for the process is considered:


