scholarly journals Appearance and Disappearance of Quasi-Liquid Layers on Ice Crystals in the Presence of Nitric Acid Gas

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 72
Author(s):  
Ken Nagashima ◽  
Josée Maurais ◽  
Ken-ichiro Murata ◽  
Yoshinori Furukawa ◽  
Patrick Ayotte ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Solid Phase ◽  
Pure Water ◽  
Liquidus Line ◽  
Spectroscopic Studies ◽  
Ice Crystals ◽  
Atmospheric Gases ◽  
Acid Gas ◽  
Ice Surfaces ◽  
Experimental Challenge

The surfaces of ice crystals near the melting point are covered with thin liquid water layers, called quasi-liquid layers (QLLs), which play crucial roles in various chemical reactions in nature. So far, there have been many spectroscopic studies of such chemical reactions on ice surfaces, however, revealing the effects of atmospheric gases on ice surfaces remains an experimental challenge. In this study, we chose HNO3 as a model atmospheric gas, and directly observed the ice basal faces by advanced optical microscopy under partial pressure of HNO3 (~10−4 Pa), relevant to those found in the atmosphere. We found that droplets (HNO3-QLLs) appeared on ice surfaces at temperatures ranging from −0.9 to −0.2 °C with an increase in temperature, and that they disappeared at temperatures ranging from −0.6 to −1.3 °C with decreasing temperature. We also found that the size of the HNO3-QLLs decreased immediately after we started reducing the temperature. From the changes in size and the liquid–solid phase diagram of the HNO3-H2O binary system, we concluded that the HNO3-QLLs did not consist of pure water, but rather aqueous HNO3 solutions, and that the temperature and HNO3 concentration of the HNO3-QLLs also coincided with those along a liquidus line.

X-ray scattering study on the crystalline and semi-crystalline structure of water/PEG mixtures in their eutectic phase diagram

Soft Matter ◽  
2020 ◽  
Vol 16 (45) ◽  
pp. 10260-10267
Author(s):  
Björn Kuttich ◽  
Alexander Matt ◽  
Christian Appel ◽  
Bernd Stühn
Keyword(s):  
Eutectic Temperature ◽  
Solid Phase ◽  
Pure Water ◽  
Liquidus Line ◽  
X Ray ◽  
Water Ice ◽  
Structure Of Water ◽  
Eutectic Phase Diagram ◽  
X Ray Scattering ◽  
Scattering Study

Water/PEG mixtures start to phase separate below the liquidus line. Above the eutectic temperature the solid phase is either pure water ice or semi-crystalline PEG. Below the eutectic line both crystals coexist, no mixed-crystalline phase is found.

ChemInform Abstract: Computational Studies of Atmospherically-Relevant Chemical Reactions in Water Clusters and on Liquid Water and Ice Surfaces

ChemInform ◽  
2015 ◽  
Vol 46 (17) ◽  
pp. no-no
Author(s):  
R. Benny Gerber ◽  
Mychel E. Varner ◽  
Audrey D. Hammerich ◽  
Sampsa Riikonen ◽  
Garold Murdachaew ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Liquid Water ◽  
Water Clusters ◽  
Computational Studies ◽  
Ice Surfaces ◽  
Atmospherically Relevant

The Construction of New Proteins. II. Design, Synthesis and Conformational Studies of Folding Units with βαβ-Topology

1986 ◽  
Vol 41 (10) ◽  
pp. 1315-1322 ◽  
Author(s):  
Manfred Mutter ◽  
Karl-Heinz Altmann ◽  
Thomas Vorherr
Keyword(s):  
Solid Phase ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Spectroscopic Studies ◽  
General Concept ◽  
Dimensional Structure ◽  
Design Synthesis ◽  
Phase Synthesis ◽  
Conformational Studies ◽  
Conformational Effects

The design, synthesis and preliminary conformational studies of two polypeptides exhibiting βαβ-type folding topologies are presented. In the design of the model peptides the general concept for the construction of new proteins developed in the preceeding paper was applied. According to this strategy, amphiphilic helices and β-sheets are linked together via hydrophilic loops to attain three-dimensional structures of higher order (‘supersecondary structures’). Com­puter-assisted molecular modelling served as a valuable tool for minimizing conformational con­straints within the molecules. The 38-residue peptide MI was synthesized using polyethylene glycol (PEG) as solubilizing polymeric support (‘Liquid-Phase synthesis'). Conformationally in­duced changes in the physico-chemical properties of the growing peptide chain stressed the significance of conformational effects in peptide synthesis reported earlier. Similar observations were made during the solid-phase synthesis of the 35-peptide MII. CD and IR spectroscopic studies revealed a high degree of secondary structure for both folding units. The present data strongly support the adoption of a three-dimensional structure for both models.

scholarly journals On the respiration of the leaves of plants

1843 ◽  
Vol 4 ◽  
pp. 466-466
Keyword(s):  
Natural Condition ◽  
Carbonic Acid ◽  
Pure Water ◽  
Atmospheric Air ◽  
Acid Gas ◽  
Series Of Experiments ◽  
As If

The author gives an account of a series of experiments on the products of the respiration of plants, and more particularly of the leaves; selecting, with this view, specimens of plants which had been previously habituated to respire constantly under an inclosure of glass; and employing, for that purpose, the apparatus which he had formerly used in experimenting on the combustion of the diamond, and consisting of two mercurial gasometers, with the addition of two hemispheres of glass closely joined together at their bases, so as to form an air-tight globular receptacle for the plant subjected to experiment. The general conclusions he deduces from his numerous experiments conducted during several years, are, first, that in leaves which are in a state of vigorous health, vegetation is always operating to restore the surrounding atmospheric air to its natural condition, by the absorption of carbonic acid and the disengagement of oxygenous gas: that this action is promoted by the influence of light, but that it continues to be exerted, although more slowly, even in the dark. Secondly, that carbonic acid is never disengaged during the healthy condition of the leaf. Thirdly, that the fluid so abundantly exhaled by plants in their vegetation is pure water, and contains no trace of carbonic acid. Fourthly, that the first portions of carbonic acid gas contained in an artificial atmosphere, are taken up with more avidity by plants than the remaining portions; as if their appetite for that pabulum had diminished by satiety.

Sources of Air Pollution

2018 ◽  
pp. 220-258
Author(s):  
Abderrezak Khelfi
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Adverse Effects ◽  
Chemical Reactions ◽  
Dust Storms ◽  
Pollution Sources ◽  
Atmospheric Gases ◽  
Secondary Pollutants ◽  
Harmful Substances ◽  
Life On Earth

This chapter describes how air is a complex natural gaseous system essential to support life on Earth. Air pollution comes from a wide variety of sources, which discharge of harmful substances into the atmosphere, causing adverse effects to humans and the environment. They can be natural or anthropogenic. Natural air pollution sources are multiple and include volcanic eruption, fire, ocean vapors, dust storms and fermentation of organic materials. However, the range and quantities of chemicals discharged into the atmosphere from industry, transport, agriculture, energy production, domestic heating, and many other human activities, have increased dramatically. Some pollutants are emitted directly into the atmosphere and are known as primary pollutants (NOx, SOx, particulate matter, etc.). Others are formed in the air as a result of chemical reactions with other pollutants and atmospheric gases; these are known as secondary pollutants like ozone. This chapter provides an overview on air pollution sources as well as the ways in which pollutants can affect human health and the environment.

Rate Constant of Solid-Phase Chemical Reactions. Theory

2021 ◽  
pp. 68-131
Author(s):  
V.I. Gol’danskii ◽  
L.I. Trakhtenberg ◽  
V.N. Fleurov
Keyword(s):  
Chemical Reactions ◽  
Rate Constant ◽  
Solid Phase ◽  
Phase Chemical

scholarly journals Growth Modes of Ice Crystals in Supercooled Water and Aqueous Solutions

1967 ◽  
Vol 6 (47) ◽  
pp. 651-662 ◽  
Author(s):  
H. R. Pruppacher
Keyword(s):  
Aqueous Solutions ◽  
Tube Wall ◽  
Pure Water ◽  
Supercooled Water ◽  
Seed Crystal ◽  
Ice Crystals ◽  
Tube Axis ◽  
Growth Modes ◽  
Water Drops ◽  
Large Water

The growth modes of ice crystals in supercooled water and various aqueous solutions were studied at different supercoolings by a motion-picture technique. ln pure water contained in plastic capillary tubes, ice dendrites formed which at supercoolings between 1 and 4°C. grew parallel to the tube axis. At supercoolings larger than 4°C. the direction of growth was inclined to the tube axis such that the dendrites hit the tube wall and afterwards proceeded growing in a new direction. As a result it appeared that the ice crystals grew in a zig-zag or screw fashion. This growth mode became enhanced when the supercooling was increased or salts were dissolved in the water. In large water drops, ice dendrites formed which at supercoolings smaller than 1°C. were co-planar with the seed crystal and between 1° and 5°C. split into two dendritic segments. At supercoolings larger than 5°C. multiple splitting of the seed crystal was observed and this became strongly enhanced when salts were dissolved in the water. Tentative explanations for these results are given.

On the mechanisms of solid-phase reversible chemical reactions in the MgO—Al2O3—SiO2 system

1998 ◽  
Vol 39 (7-8) ◽  
pp. 291-296 ◽  
Author(s):  
S. M. Logvinkov ◽  
G. D. Semchenko ◽  
D. A. Kobyzeva
Keyword(s):  
Chemical Reactions ◽  
Solid Phase ◽  
Sio2 System
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