scholarly journals Thermal Convection in the Core of Ganymede Inferred from Liquid Eutectic Fe-FeS Electrical Resistivity at High Pressures

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 875
Author(s):  
Joshua A. H. Littleton ◽  
Richard A. Secco ◽  
Wenjun Yong
Keyword(s):  
Electrical Resistivity ◽  
Thermal Convection ◽  
High Pressures ◽  
Freezing Point ◽  
Thermal Evolution ◽  
Significant Proportion ◽  
Freezing Point Depression ◽  
The Core ◽  
Liquid Transition ◽  
End Members

The core of Ganymede is suggested to be mainly Fe but with a significant proportion of S. Effects of S as a core constituent are freezing-point depression, allowing for a molten core at relatively low core temperatures, and modification of transport properties that can influence the dynamo and thermal evolution. The electrical resistivity of solid and liquid Fe-FeS (~24–30 wt.% S) was measured up to 5 GPa and thermal conductivity was calculated using the Wiedemann–Franz law. These first well-constrained experimental data on near eutectic Fe-FeS compositions showed intermediate values of electrical and thermal conductivities compared to the end-members. Eutectic temperatures were delineated from the solid to liquid transition, inferred from sharp changes in electrical resistivity, at each pressure. Combined with thermal models, our calculated estimates of the adiabatic heat flow of a molten Fe-FeS eutectic composition core model of Ganymede showed that thermal convection is permissible.

Adiabatic Heat Flow in Mercury with a Fe-8.5wt%Si Core

2021 ◽  
Author(s):  
Meryem Berrada ◽  
Richard Secco ◽  
Wenjun Yong
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Internal Structure ◽  
High Pressures ◽  
Inner Core ◽  
Thermal Evolution ◽  
The Core ◽  
Thermally Driven ◽  
Wire Method ◽  
Core Conditions

<p>Recent theoretical studies have tried to constrain Mercury’s internal structure and composition using thermal evolution models. The presence of a thermally stratified layer of Fe-S at the top of an Fe-Si core has been suggested, which implies a sub-adiabatic heat flow on the core side of the CMB. In this work, the adiabatic heat flow at the top of the core was estimated using the electronic component of thermal conductivity (k<sub>el</sub>), a lower bound for thermal conductivity. Direct measurements of electrical resistivity (ρ) of Fe-8.5wt%Si at core conditions can be related to k<sub>el</sub> using the Wiedemann-Franz law. Measurements were carried out in a 3000 ton multi-anvil press using a 4-wire method. The integrity of the samples at high pressures and temperatures was confirmed with electron-microprobe analysis of quenched samples at various conditions. Unexpected behaviour at low temperatures between 6-8 GPa may indicate an undocumented phase transition. Measurements of ρ at melting seem to remain constant at 127 µΩ·cm from 10-24 GPa, on both the solid and liquid side of the melting boundary. The adiabatic heat flow at the core side of Mercury’s core-mantle boundary is estimated between 21.8-29.5 mWm<sup>-2</sup>, considerably higher than most models of an Fe-S or Fe-Si core yet similar to models of an Fe core. Comparing these results with thermal evolution models suggests that Mercury’s dynamo remained thermally driven up to 0.08-0.22 Gyr, at which point the core became sub-adiabatic and stimulated a change from dominant thermal convection to dominant chemical convection arising from the growth of an inner core. Simply considering the internal structure of Mercury, these results support the capture of Mercury into a 3:2 resonance orbit during the thermally driven era of the dynamo.</p>

Depression of freezing temperature of water and water solutions in porous materials

1989 ◽  
Vol 54 (10) ◽  
pp. 2644-2647 ◽  
Author(s):  
Petr Schneider ◽  
Jiří Rathouský
Keyword(s):  
Water Vapor ◽  
Porous Materials ◽  
Inorganic Salt ◽  
Freezing Point ◽  
Freezing Temperature ◽  
Inorganic Salts ◽  
Freezing Point Depression ◽  
Salt Solutions ◽  
Water Solutions

In porous materials filled with water or water solutions of inorganic salts, water freezes at lower temperatures than under normal conditions; the reason is the decrease of water vapor tension above the convex meniscus of liquid in pores. The freezing point depression is not very significant in pores with radii from 0.05 μm to 10 μm (about 0.01-2.5 K). Only in smaller pores, especially when filled with inorganic salt solutions, this depression is important.

scholarly journals Freezing point depression and freeze-thaw damage by nanofluidic salt trapping

2020 ◽  
Vol 5 (12) ◽  
Author(s):  
Tingtao Zhou ◽  
Mohammad Mirzadeh ◽  
Roland J.-M. Pellenq ◽  
Martin Z. Bazant
Keyword(s):  
Freezing Point ◽  
Freezing Point Depression ◽  
Freeze Thaw

Colloid osmotic pressure changes of dog's blood exposed to different mixtures of CO2 and air

1978 ◽  
Vol 44 (2) ◽  
pp. 254-257 ◽  
Author(s):  
Y. Kakiuchi ◽  
A. B. DuBois ◽  
D. Gorenberg
Keyword(s):  
Red Blood Cells ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Blood Cells ◽  
Freezing Point ◽  
Colloid Osmotic Pressure ◽  
Red Cell ◽  
Freezing Point Depression ◽  
Pressure Changes ◽  
Different Levels

Hansen's membrane manometer method for measuring plasma colloid osmotic pressure was used to obtain the osmolality changes of dogs breathing different levels of CO2. Osmotic pressure was converted to osmolality by calibration of the manometer with saline and plasma, using freezing point depression osmometry. The addition of 10 vol% of CO2 to tonometered blood caused about a 2.0 mosmol/kg H2O increase of osmolality, or 1.2% increase of red blood cell volume. The swelling of the red blood cells was probably due to osmosis caused by Cl- exchanged for the HCO3- which was produced rapidly by carbonic anhydrase present in the red blood cells. The change in colloid osmotic pressure accompanying a change in co2 tension was measured on blood obtained from dogs breathing different CO2 mixtures. It was approximately 0.14 mosmol/kg H2O per Torr Pco2. The corresponding change in red cell volume could not be calculated from this because water can exchange between the plasma and tissues.

Study on Mechanical Automation with Design of Rapid Milk Detector Based on Freezing Point

2013 ◽  
Vol 703 ◽  
pp. 282-286
Author(s):  
Ren Cai Zhang ◽  
Xiang Yu ◽  
Xing Ju Liu ◽  
Jin Hai Zhai ◽  
Zhen Wu Ning
Keyword(s):  
Integrated Circuit ◽  
Temperature Sensor ◽  
High Efficiency ◽  
Freezing Point ◽  
Electronic Control ◽  
Freezing Point Depression ◽  
Electronic Control System ◽  
Freezing Curve ◽  
Rack Mechanism

An efficient automated milk detector based on freezing point depression is designed. This detector shares characters of high efficiency and good stability with accuracy and automation. Its main parts include temperature sensor of IC (Integrated Circuit), pinion-rack mechanism and crank-rocker mechanism and electronic control system. Monitoring in-situ change of milk freezing curve and developing efficiency of sampling can be available by means of pinion-rack mechanism and IC temperature sensor mechatronics design. As a result, adulterating status of milk can be discriminated in a rapid and accurate and automated way. The detector may be employed to detect liquid foods other than milk as well.

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