scholarly journals Structure and water attachment rates of ice in the atmosphere: role of nitrogen

2019 ◽  
Vol 21 (35) ◽  
pp. 19594-19611 ◽  
Author(s):  
Pablo Llombart ◽  
Ramon M. Bergua ◽  
Eva G. Noya ◽  
Luis G. MacDowell
Keyword(s):  
Crystal Growth ◽  
Computer Simulations ◽  
Growth Rates ◽  
Ice Surface

In this work we perform computer simulations of the ice surface in order to elucidate the role of nitrogen in the crystal growth rates and crystal habits of snow in the atmosphere.

Molecular dynamics study on the role of solvation water in the adsorption of hyperactive AFP to the ice surface

2018 ◽  
Vol 20 (39) ◽  
pp. 25365-25376 ◽  
Author(s):  
Joanna Grabowska ◽  
Anna Kuffel ◽  
Jan Zielkiewicz
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulations ◽  
Early Stages ◽  
Ice Surface

Using computer simulations, the early stages of the adsorption of the CfAFP molecule to the ice surface were analyzed.

Role of polymer chemistry in influencing crystal growth rates from amorphous felodipine

CrystEngComm ◽  
2010 ◽  
Vol 12 (8) ◽  
pp. 2390 ◽  
Author(s):  
Umesh S. Kestur ◽  
Lynne S. Taylor
Keyword(s):  
Crystal Growth ◽  
Growth Rates ◽  
Polymer Chemistry

scholarly journals Surface phase transitions and crystal habits of ice in the atmosphere

2020 ◽  
Vol 6 (21) ◽  
pp. eaay9322 ◽  
Author(s):  
Pablo Llombart ◽  
Eva G. Noya ◽  
Luis G. MacDowell
Keyword(s):  
Phase Transitions ◽  
Crystal Growth ◽  
Growth Rates ◽  
Large Scale ◽  
Crystal Surface ◽  
Climate Modeling ◽  
Ice Surface ◽  
Snow Crystal ◽  
Surface Phase Transitions ◽  
Step Density

With climate modeling predicting a raise of at least 2°C by year 2100, the fate of ice has become a serious concern, but we still do not understand how ice grows (or melts). In the atmosphere, crystal growth rates of basal and prism facets exhibit an enigmatic temperature dependence and crossover up to three times in a range between 0° and −40°. Here, we use large-scale computer simulations to characterize the ice surface and identify a sequence of previously unidentified phase transitions on the main facets of ice crystallites. Unexpectedly, we find that as temperature is increased, the crystal surface transforms from a disordered phase with proliferation of steps to a smooth phase with small step density. This causes the anomalous increase of step free energies and provides the long sought explanation for the enigmatic crossover of snow crystal growth rates found in the atmosphere.

Comparison of copper sulphate pentahydrate growth rates determined by different methods

1990 ◽  
Vol 55 (7) ◽  
pp. 1691-1707 ◽  
Author(s):  
Miloslav Karel ◽  
Jiří Hostomský ◽  
Jaroslav Nývlt ◽  
Axel König
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Fluidized Bed ◽  
Growth Rates ◽  
Copper Sulphate ◽  
Crystal Growth Rate ◽  
Effect Of Temperature ◽  
Rotating Disc ◽  
Shape Factors ◽  
Data Treatment

Crystal growth rates of copper sulphate pentahydrate (CuSO4.5 H2O) determined by different authors and methods are compared. The methods included in this comparison are: (i) Measurement on a fixed crystal suspended in a streaming solution, (ii) measurement on a rotating disc, (iii) measurement in a fluidized bed, (iv) measurement in an agitated suspension. The comparison involves critical estimation of the supersaturation used in measurements, of shape factors used for data treatment and a correction for the effect of temperature. Conclusions are drawn for the choice of values to be specified when data of crystal growth rate measurements are published.

Kinetics of the Crystallization of Potassium Sulfate

1993 ◽  
Vol 58 (8) ◽  
pp. 1848-1854 ◽  
Author(s):  
Miroslav Karel ◽  
Jaroslav Nývlt
Keyword(s):  
Experimental Data ◽  
Crystal Growth ◽  
Growth Rates ◽  
Potassium Sulfate ◽  
Kinetics Of

The kinetics of the crystallization of potassium sulfate has been determined using the MSMPR technique. Values of the nucleation and crystal growth rates evaluated from the experimental data are compared with the corresponding literature data.

scholarly journals The role of radiolysis in the modelling of C2H4O2 isomers and dimethyl ether in cold dark clouds

2020 ◽  
Vol 500 (3) ◽  
pp. 3414-3424
Author(s):  
Alec Paulive ◽  
Christopher N Shingledecker ◽  
Eric Herbst
Keyword(s):  
Gas Phase ◽  
Dimethyl Ether ◽  
Recent Observation ◽  
Cosmic Ray ◽  
Thermal Method ◽  
Dark Clouds ◽  
Ice Surface ◽  
Dust Grain ◽  
Complex Organic

ABSTRACT Complex organic molecules (COMs) have been detected in a variety of interstellar sources. The abundances of these COMs in warming sources can be explained by syntheses linked to increasing temperatures and densities, allowing quasi-thermal chemical reactions to occur rapidly enough to produce observable amounts of COMs, both in the gas phase, and upon dust grain ice mantles. The COMs produced on grains then become gaseous as the temperature increases sufficiently to allow their thermal desorption. The recent observation of gaseous COMs in cold sources has not been fully explained by these gas-phase and dust grain production routes. Radiolysis chemistry is a possible non-thermal method of producing COMs in cold dark clouds. This new method greatly increases the modelled abundance of selected COMs upon the ice surface and within the ice mantle due to excitation and ionization events from cosmic ray bombardment. We examine the effect of radiolysis on three C2H4O2 isomers – methyl formate (HCOOCH3), glycolaldehyde (HCOCH2OH), and acetic acid (CH3COOH) – and a chemically similar molecule, dimethyl ether (CH3OCH3), in cold dark clouds. We then compare our modelled gaseous abundances with observed abundances in TMC-1, L1689B, and B1-b.

scholarly journals Role of carbon allocation efficiency in the temperature dependence of autotroph growth rates

2018 ◽  
Vol 115 (31) ◽  
pp. E7361-E7368 ◽  
Author(s):  
Bernardo García-Carreras ◽  
Sofía Sal ◽  
Daniel Padfield ◽  
Dimitrios-Georgios Kontopoulos ◽  
Elvire Bestion ◽  
...  
Keyword(s):  
Growth Rate ◽  
Temperature Dependence ◽  
Growth Rates ◽  
Carbon Allocation ◽  
Thermal Sensitivity ◽  
Potential Growth ◽  
Allocation Efficiency ◽  
Population Growth Rates ◽  
Performance Curves

Relating the temperature dependence of photosynthetic biomass production to underlying metabolic rates in autotrophs is crucial for predicting the effects of climatic temperature fluctuations on the carbon balance of ecosystems. We present a mathematical model that links thermal performance curves (TPCs) of photosynthesis, respiration, and carbon allocation efficiency to the exponential growth rate of a population of photosynthetic autotroph cells. Using experiments with the green alga, Chlorella vulgaris, we apply the model to show that the temperature dependence of carbon allocation efficiency is key to understanding responses of growth rates to warming at both ecological and longer-term evolutionary timescales. Finally, we assemble a dataset of multiple terrestrial and aquatic autotroph species to show that the effects of temperature-dependent carbon allocation efficiency on potential growth rate TPCs are expected to be consistent across taxa. In particular, both the thermal sensitivity and the optimal temperature of growth rates are expected to change significantly due to temperature dependence of carbon allocation efficiency alone. Our study provides a foundation for understanding how the temperature dependence of carbon allocation determines how population growth rates respond to temperature.

The evolving role of animal laboratories in physiology instruction

2005 ◽  
Vol 29 (3) ◽  
pp. 144-150 ◽  
Author(s):  
Alice W. Ra'anan
Keyword(s):  
Medical Education ◽  
Active Learning ◽  
Computer Simulations ◽  
Contributing Factors ◽  
Educational Impact

Laboratory exercises are intended to illustrate concepts and add an active learning component to courses. Since the 1980s, there has been a decline in animal laboratories offered in conjunction with medical physiology courses. The most important single reason for this is cost, but other contributing factors include the development of computer simulations, changes in medical education, and pressure from antivivisectionists. Unfortunately, the elimination of animal laboratories has occurred with relatively little consideration of the educational impact of this change. Although computer simulations are considered effective in helping students acquire basic physiological concepts, there is evidence some students acquire a more thorough understanding of the material through the more advanced and challenging experience of an animal laboratory. The fact that such laboratories offer distinct educational advantages should be taken into account when courses are designed.

scholarly journals On the Mechanism of Cuprate Crystal Growth: The Role of Mixed Metal Carbonates

2015 ◽  
Vol 25 (29) ◽  
pp. 4700-4707 ◽  
Author(s):  
David C. Green ◽  
Rebecca Boston ◽  
Stefan Glatzel ◽  
Martin R. Lees ◽  
Stuart C. Wimbush ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Mixed Metal ◽  
Metal Carbonates
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