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相关概念视频

Phase Transitions: Melting and Freezing02:39

Phase Transitions: Melting and Freezing

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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...
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Freezing Point Depression and Boiling Point Elevation03:12

Freezing Point Depression and Boiling Point Elevation

35.0K
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...
35.0K
Cryo-electron Microscopy01:28

Cryo-electron Microscopy

3.4K
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...
3.4K
Decreased Body Temperature01:29

Decreased Body Temperature

639
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...
639
Censoring Survival Data01:09

Censoring Survival Data

125
Survival analysis is a statistical method used to analyze time-to-event data, often employed in fields such as medicine, engineering, and social sciences. One of the key challenges in survival analysis is dealing with incomplete data, a phenomenon known as "censoring." Censoring occurs when the event of interest (such as death, relapse, or system failure) has not occurred for some individuals by the end of the study period or is otherwise unobservable, and it might have many different...
125
Phase Transitions: Sublimation and Deposition02:33

Phase Transitions: Sublimation and Deposition

17.2K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
17.2K

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相关实验视频

Updated: Jul 15, 2025

Laser-Induced Fluorescence Emission L.I.F.E. as Novel Non-Invasive Tool for In-Situ Measurements of Biomarkers in Cryospheric Habitats
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Laser-Induced Fluorescence Emission L.I.F.E. as Novel Non-Invasive Tool for In-Situ Measurements of Biomarkers in Cryospheric Habitats

Published on: October 26, 2019

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在冰中潜伏?

Jon Cohen

    Science (New York, N.Y.)
    |September 28, 2023
    PubMed
    概括

    气候变化可能会从北极永久土中释放古老的病原体. 这种融化永久土可能会暴露潜伏的病毒和细菌, 构成全球健康威胁.

    科学领域:

    • 环境科学
    • 微生物学
    • 公共卫生

    背景情况:

    • 北极永久土中含有古老的微生物,包括病毒和细菌,
    • 全球气候变化导致的气温上升正在加速永久土的融化.
    • 这些古老的病原体对全球健康构成前所未有的风险.

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    相关实验视频

    Last Updated: Jul 15, 2025

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    Laser-Induced Fluorescence Emission L.I.F.E. as Novel Non-Invasive Tool for In-Situ Measurements of Biomarkers in Cryospheric Habitats

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    Removal of Exogenous Materials from the Outer Portion of Frozen Cores to Investigate the Ancient Biological Communities Harbored Inside
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