Low-temperature reactions and cool flames in an unstirred, static reactor at terrestrial and reduced-gravity

2021 ◽  
Author(s):  
Michael Robert Foster
Keyword(s):  
Low Temperature ◽  
Reduced Gravity ◽  
Cool Flames

Low-temperature oxidation and cool flames of propane

1954 ◽  
Vol 221 (1145) ◽  
pp. 151-170 ◽  
Keyword(s):  
Low Temperature ◽  
Thermal Instability ◽  
Analytical Study ◽  
Simple Explanation ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Cool Flame ◽  
Cool Flames ◽  
Oxidation Of Hydrocarbons ◽  
Flame Oxidation

A detailed analytical study of the cool-flame oxidation of propane has been carried out using a continuous-flow technique with a view to the further elucidation of the mechanism of the low-temperature oxidation of hydrocarbons. The formation of the three theoretically possible aldehydes has been demonstrated and the initially formed peroxide shown to be hydrogen peroxide. Measurements of the yields of the different products formed under varying conditions of temperature, composition and time of contact have been made and correlated with measurements of the luminous intensity and temperature of the flame. The results confirm the earlier conclusions of Norrish (1948) that aldehydes are the important branching agents in the temperature range of 300 to 400°C, and a detailed scheme based on that proposed earlier has been developed to account for the observations. The scheme has further been shown to allow of a simple explanation of the origin of the periodic character of the cool flame in terms of the thermal instability of the normal slow reaction.

The ignition and flame reactions of ethylene oxide

1949 ◽  
Vol 199 (1058) ◽  
pp. 328-351 ◽  
Keyword(s):  
Low Temperature ◽  
Ethylene Oxide ◽  
High Temperatures ◽  
Atmospheric Pressure ◽  
Ignition Limit ◽  
Constant Volume ◽  
Spontaneous Ignition ◽  
Ignition System ◽  
Cool Flames ◽  
Overall Reactions

Spontaneous ignition pressure-temperature relationships of ethylene oxide-oxygen and -air mixtures have been studied. A low-temperature ignition system exists and cool flames can be initiated in air at atmospheric pressure and below. The propagation of cool flames through cold mixtures imder this condition has not, however, been observed. Nevertheless, ethylene oxide itself propagates a decomposition flame and is inflammable at constant volume in admixture with air for all percentages above 3*6. The products of decomposition are almost entirely accounted for by the two overall reactions: C 2 H 4 0 = CH 4 + CO +17-2 kcal., 2C 2 H 4 0 = C 2 H 4 + 2CO + 2H 2 - 2 x 6-15 kcal. These reactions are also very significant in the non-luminous flames that have been found to be propagated through the richer mixtures of ethylene oxide with air. It is shown that the latter flames are initiated only at high temperatures, of the same order as for normal flames, and that they correspond with the non-luminous flames occurring near to the hightemperature spontaneous ignition limit of richer mixtures.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Sign in / Sign up

Export Citation Format

Share Document