A glimpse into rapid freezing processes in clay with x-ray tomography

2021 ◽  
Author(s):  
Giorgia Amato ◽  
Edward Andò ◽  
Chuangxin Lyu ◽  
Gioacchino Viggiani ◽  
Gudmund Reinar Eiksund
Keyword(s):  
Rapid Freezing ◽  
X Ray

Diffusible ions in amebae studied by scanning electron microscopy and X-ray microanalysis

1978 ◽  
Vol 36 (2) ◽  
pp. 112-113
Author(s):  
D. Schäfer ◽  
K. Zierold
Keyword(s):  
Calcium Ions ◽  
Aluminum Foil ◽  
Amoeba Proteus ◽  
Rapid Freezing ◽  
Cultivation Medium ◽  
X Ray ◽  
Freeze Dried ◽  
Energy Dispersive Microanalysis ◽  
Scanning Electron ◽  
Investigation Procedure

Calcium ions are involved in the regulation of ameboid movement but, so far, little is known about the distribution of calcium and other electrolyte ions in the amebae. This problem seems solvable by X-ray microanalysis with the scanning electron microscope (SEM). For this purpose Amoeba proteus was placed in the cultivation medium (Chalkey's solution) on the specimen stub covered with aluminum foil. Rapid freezing was done in liquid Freon 12 or propane precooled by liquid nitrogen. The specimens were either freeze-dried at -45° C for 15 hours and then coated with carbon or kept in the deep-frozen state throughout the preparation and investigation procedure by using a special cooling chain method. After coating ice was sublimated in the SEM under visual control until the ameboid structures became visible. Energy-dispersive microanalysis was done at 12.5 keV and 0.1 - 0.5 nA.

scholarly journals Laboratory exploration of mineral precipitates from Europa's subsurface ocean

2021 ◽  
Vol 54 (5) ◽  
Author(s):  
Stephen P. Thompson ◽  
Hilary Kennedy ◽  
Benjamin M. Butler ◽  
Sarah J. Day ◽  
Emmal Safi ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
The Other ◽  
Rapid Freezing ◽  
Precipitation Sequence ◽  
Equilibrium Thermodynamics ◽  
Slow Cooling ◽  
X Ray ◽  
Hydrated Sulfate ◽  
Subsurface Ocean

The precipitation of hydrated phases from a chondrite-like Na–Mg–Ca–SO4–Cl solution is studied using in situ synchrotron X-ray powder diffraction, under rapid- (360 K h−1, T = 250–80 K, t = 3 h) and ultra-slow-freezing (0.3 K day−1, T = 273–245 K, t = 242 days) conditions. The precipitation sequence under slow cooling initially follows the predictions of equilibrium thermodynamics models. However, after ∼50 days at 245 K, the formation of the highly hydrated sulfate phase Na2Mg(SO4)2·16H2O, a relatively recent discovery in the Na2Mg(SO4)2–H2O system, was observed. Rapid freezing, on the other hand, produced an assemblage of multiple phases which formed within a very short timescale (≤4 min, ΔT = 2 K) and, although remaining present throughout, varied in their relative proportions with decreasing temperature. Mirabilite and meridianiite were the major phases, with pentahydrite, epsomite, hydrohalite, gypsum, blödite, konyaite and loweite also observed. Na2Mg(SO4)2·16H2O was again found to be present and increased in proportion relative to other phases as the temperature decreased. The results are discussed in relation to possible implications for life on Europa and application to other icy ocean worlds.

X-ray microanalysis of ion distributions in rye leaf cells at sub-zero temperatures

1990 ◽  
Vol 48 (2) ◽  
pp. 174-175
Author(s):  
Kaarina Pihakaski-Maunsbach ◽  
Diana M.R. Harvey
Keyword(s):  
Plant Cells ◽  
Freeze Substitution ◽  
Winter Rye ◽  
Rapid Freezing ◽  
Cell Organelles ◽  
X Ray ◽  
Ion Distributions ◽  
Secale Cereale L ◽  
Whole Plants ◽  
Freezing Injuries

X-ray microanalysis has been used in a new application to study potassium changes induced by cold acclimation and freezing injuries in plant cells. Potassium is a key ion since it is the major free cation present in the plant cytoplasm. Most studies dealing with freezing injuries have been conducted on whole plants or pieces of tissues thawn after freezing. Rapid freezing of tissue pieces from defined temperatures, followed by freeze-substitution and analysis of ions by X-ray microanalysis from different cell organelles, allows conclusions about the temperature at which damage occurs.Seeds of winter rye (Secale cereale L. cv Voima) were germinated in vermiculite at 25 °C for 3 days (non-acclimated, NA). A portion of the seedlings were transferred after 2 days to 5 °C for 4 weeks (cold acclimated, A). Specimens for freeze substitution were taken from the growing temperatures, and from the temperatures where 50% (LT50) and 100% (LT100) of the plants were killed.

Rapid Freezing of Small Biopsies and Standard for Cryosectioning and X-Ray Microanalysis

1989 ◽  
Vol 92 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Kåre E. Tvedt ◽  
Gunnar Kopstad ◽  
Jostein Halgunset ◽  
Olav A. Haugen
Keyword(s):  
Rapid Freezing ◽  
X Ray

scholarly journals Ultrastructure and energy-dispersive x-ray microanalysis of cartilage after rapid freezing, low temperature freeze drying, and embedding in Spurr's resin.

1985 ◽  
Vol 33 (10) ◽  
pp. 1073-1079 ◽  
Author(s):  
J Appleton ◽  
R Lyon ◽  
K J Swindin ◽  
J Chesters
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Energy Dispersive ◽  
Freezing Process ◽  
Rapid Freezing ◽  
Thin Sections ◽  
X Ray ◽  
Freeze Dried ◽  
Rapid Production ◽  
Ideal Method

In order to undertake meaningful high-resolution x-ray microanalysis of tissues, methods should be used that minimize the introduction of artefacts produced by loss or translocation of ions. The most ideal method is rapid freezing but the subsequent sectioning of frozen tissues is technically difficult. An alternative method is to freeze dry the tissues at a low temperature, and then embed them in resin. This facilitates the rapid production of reproducible thin sections. With freeze-dried, embedded hypertrophic cartilage, the morphology was similar to that seen using aqueous fixatives even when no additional electron density is introduced by the use of osmium vapor. Energy-dispersive analysis of specific areas show that little or no loss or migration of ions occurs from structures such as mitochondria. Mitochondrial granules consisting of calcium and phosphorus precipitates were not observed except where the cells were damaged as a result of the freezing process. This may suggest that these granules only appear when tissue is damaged because of inadequate preservation.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

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