Amorphous ice still a puzzle

Nature ◽  
1987 ◽  
Vol 326 (6116) ◽  
pp. 823-823 ◽  
Author(s):  
John Maddox
Keyword(s):  
Amorphous Ice

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

A metal- coating Chamber for High-Resolution Cryo-SEM

1990 ◽  
Vol 48 (1) ◽  
pp. 418-419
Author(s):  
John G. Sheehan
Keyword(s):  
High Resolution ◽  
Colloidal Suspensions ◽  
Metal Coating ◽  
Colloidal Interactions ◽  
Amorphous Ice ◽  
High Vapor ◽  
Particulate Coatings ◽  
20 Nm ◽  
Film Nucleation ◽  
Coating Chamber

Improvements in particulate coatings for printable paper require understanding mechanisms of colloidal interactions in paper coating suspensions. One way to deduce colloidal interactions is to mage particle spacings and orientations at high resolution with cryo-SEM. Recent improvements in cryo-SEM technique have increased resolution enough to image particles in coating paints,vhich are sometimes smaller than 100 nm. In this report, a metal-coating chamber is described for preparation of colloidal suspensions for cryo-SEM at resolution down to 20 nm. It was found that etching is not necessary to achieve this resolution.A 120 K cryo-SEM sample will remain in an SEM for hours without noticeable condensation of imorphous ice. This is due to the high vapor pressure of vapor-condensed amorphous ice, measured by Kouchi. However, clean vacuum is required to coat samples with the thinnest possible continuous metal films which are required for high magnification SEM. Vapor contaminants, especially hrydrocarbons, are known to interfere with thin-film nucleation and growth so that more metal is needed to form continuous films, and resolution is decreased. That is why the metal-coating chamber in fig. 1 is designed for the cleanest possible vacuum. Feedthroughs for the manipulator md the shutter, which are operated during metal coating, are sealed with leak-proof stainless-steel Dellows. The transfer rod slides through a baseplate feedthrough that is double o-ring sealed.

Structure and dynamics of interface between forsterite glass and amorphous ice

2020 ◽  
Vol 760 ◽  
pp. 138028
Author(s):  
Ayane Kubo ◽  
Junya Nishizawa ◽  
Tomoko Ikeda-Fukazawa
Keyword(s):  
Amorphous Ice ◽  
Structure And Dynamics

From parallel to single crystallization kinetics in high-density amorphous ice

2013 ◽  
Vol 88 (17) ◽  
Author(s):  
Markus Seidl ◽  
Katrin Amann-Winkel ◽  
Philip H. Handle ◽  
Gerhard Zifferer ◽  
Thomas Loerting
Keyword(s):  
Crystallization Kinetics ◽  
High Density ◽  
Amorphous Ice

Convergent Raman Features in High Density Amorphous Ice, Ice VII, and Ice VIII under Pressure

2011 ◽  
Vol 115 (14) ◽  
pp. 3756-3760 ◽  
Author(s):  
Yukihiro Yoshimura ◽  
Sarah T. Stewart ◽  
Maddury Somayazulu ◽  
Ho Kwang Mao ◽  
Russell J. Hemley
Keyword(s):  
High Density ◽  
Amorphous Ice

Vacuum ultraviolet photoelectric emission from amorphous ice

1978 ◽  
Vol 68 (4) ◽  
pp. 1997-1999 ◽  
Author(s):  
Bill Baron ◽  
Dale Hoover ◽  
Ferd Williams
Keyword(s):  
Vacuum Ultraviolet ◽  
Amorphous Ice ◽  
Photoelectric Emission

Infrared spectra of amorphous ice

1972 ◽  
Vol 42 (1) ◽  
pp. 17-18 ◽  
Author(s):  
U. Buontempo
Keyword(s):  
Infrared Spectra ◽  
Amorphous Ice

scholarly journals Amorphous Mixtures of Ice and C60 Fullerene

2020 ◽  
Author(s):  
Siriney Halukeerthi ◽  
Jacob J. Shephard ◽  
Sukhpreet Talewar ◽  
John S. O. Evans ◽  
Alexander Rosu-Finsen ◽  
...  
Keyword(s):  
Phase Separation ◽  
Percolation Threshold ◽  
Thermal Desorption ◽  
Crystallization Temperature ◽  
Space Exploration ◽  
Chemical Species ◽  
C60 Fullerene ◽  
Volume Percent ◽  
Water Desorption ◽  
Amorphous Ice

Carbon and ice make up a substantial proportion of our Universe. Recent space exploration has shown that these two chemical species often coexist including on comets, asteroids and in the interstellar medium. Here we prepare mixtures of C<sub>60</sub> fullerene and H<sub>2</sub>O by vapor co-deposition at 90 K with molar C<sub>60</sub>:H<sub>2</sub>O ratios ranging from 1:1254 to 1:5. The C<sub>60</sub> percolation threshold is found between the 1:132 and 1:48 samples, corresponding to a transition from matrix-isolated C<sub>60</sub> molecules to percolating C<sub>60</sub> domains that confine the H<sub>2</sub>O. Below this threshold, the crystallization and thermal desorption properties of H<sub>2</sub>O are not significantly affected by the C<sub>60</sub>, whereas the crystallization temperature of H<sub>2</sub>O is shifted towards higher temperatures for the C<sub>60</sub>-rich samples. These C<sub>60</sub>-rich samples also display exotherms corresponding to the crystallization of C<sub>60</sub> as the two components undergo phase separation. More than 60 volume percent C<sub>60</sub> is required to significantly affect the desorption properties of H<sub>2</sub>O. A thick blanket of C<sub>60</sub> on top of pure amorphous ice is found to display large cracks due to water desorption. These findings may help understand the recently observed unusual surface features and the H<sub>2</sub>O weather cycle on the 67P/Churyumov–Gerasimenko comet.

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