New Observations on the Low Temperature Reaction between Hydrogen Sulphide and Sulphur Dioxide : A Novel Method for Analysing Milligram Quantities of Hydrogen Sulphide in the Presence of Carbon Dioxide

1959 ◽  
Vol 12 (3) ◽  
pp. 424 ◽  
Author(s):  
IK Gregor ◽  
RL Martin
Keyword(s):  
Carbon Dioxide ◽  
Low Temperature ◽  
Hydrogen Sulphide ◽  
Sulphur Dioxide ◽  
High Vacuum ◽  
Temperature Reaction ◽  
Liquid Sulphur ◽  
Vacuum Method ◽  
Novel Method ◽  
Vacuum Fractionation

When an anhydrous mixture of liquid hydrogen sulphide and liquid sulphur dioxide contained in a sealed tube at -78 �C is gently warmed, the liquid remains clear until the temperature reaches c. -40 �C, when sulphur is slowly deposited. Careful measurements reveal that the two compounds always react in the mole ratio, H2S : SO2 = 3 : 2, which contrasts with the stoichiometric equation 2H2S + SO2 =2H2O + 3S, widely quoted for their reaction in the moist gaseous phase or in aqueous solution. This low temperature reaction forms the basis of a novel high vacuum method for estimating milligram quantities of hydrogen sulphide when in the presence of gases, such as carbon dioxide, whose volatilities are sufficiently similar to preclude the use of normal low-temperature vacuum fractionation methods.

The combustion of hydrogen sulphide studied by flash photolysis and kinetic spectroscopy

1957 ◽  
Vol 240 (1222) ◽  
pp. 293-303 ◽  
Keyword(s):  
Low Temperature ◽  
Absorption Spectra ◽  
Hydrogen Sulphide ◽  
Sulphur Dioxide ◽  
Flash Photolysis ◽  
Light Emission ◽  
Inert Gas ◽  
Large Excess ◽  
Kinetic Spectroscopy ◽  
Combustion Of Hydrogen

The combustion of hydrogen sulphide has been investigated by the method of kinetic spectroscopy and flash photolysis. If no large excess of inert gas is present the reaction produces sulphur dioxide. The reaction has been shown to take place in steps in which the radicals SH and OH participate. Simultaneously with the appearance of the sulphur dioxide; a light emission has been observed which is attributed to the process: SO + O→SO2 + hv . In the presence of a large excess of inert gas the reaction results in S 2 O 2 . It has been shown that the formation of S 2 O 2 is favoured by a low temperature. Flash photolysis of hydrogen sulphide, sulphur dioxide and S 2 O 2 has also been investigated. In the last two cases the absorption spectra disappear temporarily. Inert gas prevents the disappearance of the SO 2 , but not that of S 2 O 2 . From an analysis of our results a mechanism for the combustion of hydrogen sulphide is derived and discussed.

Dicyclohexanecarbonylsulphate: a precursor of cyclohexyloxocarbenium ions

1977 ◽  
Vol 55 (2) ◽  
pp. 355-359 ◽  
Author(s):  
E. Montoneri ◽  
L. Giuffré ◽  
M. Cassago ◽  
E. Tempesti ◽  
M. Fornaroli
Keyword(s):  
Low Temperature ◽  
Sulphur Dioxide ◽  
Liquid Sulphur ◽  
Sulphur Trioxide ◽  
Equimolar Solution

Dicyclohexanecarbonyl sulphate (1) is the prevailing species in the equimolar solution of cyclohexanecarboxylic anhydride and sulphur trioxide in liquid sulphur dioxide. The ionization of 1 to cyclohexyloxocarbenium ions occurs only in the presence of excess sulphur trioxide. Both 1 and C6H11CO+ are stable only in solution and at low temperature.

High-Vacuum Evaporation and a Cryostage to Observe Fractured Yeast

1988 ◽  
Vol 46 ◽  
pp. 256-257
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Eugene L. Vigil
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Standard Specimen ◽  
High Vacuum ◽  
Specimen Holder ◽  
Sputter Coating ◽  
Fresh Frozen ◽  
Gain Access ◽  
Scanning Electron ◽  
Transfer Device

Investigators have long realized the potential advantages of using a low temperature (LT) stage to examine fresh, frozen specimens in a scanning electron microscope (SEM). However, long working distances (W.D.), thick sputter coatings and surface contamination have prevented LTSEM from achieving results comparable to those from TEM freeze etch. To improve results, we recently modified techniques that involve a Hitachi S570 SEM, an Emscope SP2000 Sputter Cryo System and a Denton freeze etch unit. Because investigators have frequently utilized the fractured E face of the plasmalemma of yeast, this tissue was selected as a standard for comparison in the present study.In place of a standard specimen holder, a modified rivet was used to achieve a shorter W.D. (1 to -2 mm) and to gain access to the upper detector. However, the additional height afforded by the rivet, precluded use of the standard shroud on the Emscope specimen transfer device. Consequently, the sample became heavily contaminated (Fig. 1). A removable shroud was devised and used to reduce contamination (Fig. 2), but the specimen lacked clean fractured edges. This result suggested that low vacuum sputter coating was also limiting resolution.

scholarly journals Research on Performance Test System of Space Harmonic Reducer in High Vacuum and Low Temperature Environment

Machines ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Jing Wang ◽  
Zhihua Wan ◽  
Zhurong Dong ◽  
Zhengguo Li
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Performance Test ◽  
High Reliability ◽  
High Vacuum ◽  
Test System ◽  
Low Noise ◽  
Speed Ratio ◽  
Space Harmonic ◽  
Temperature Environment

The harmonic reducer, with its advantages of high precision, low noise, light weight, and high speed ratio, has been widely used in aerospace solar wing deployment mechanisms, antenna pointing mechanisms, robot joints, and other precision transmission fields. Accurately predicting the performance of the harmonic reducer under various application conditions is of great significance to the high reliability and long life of the harmonic reducer. In this paper, a set of automatic harmonic reducer performance test systems is designed. By using the CANOpen bus interface to control the servo motor as the drive motor, through accurately controlling the motor speed and rotation angle, collecting the angle, torque, and current in real time, the life cycle test of space harmonic reducer was carried out in high vacuum and low temperature environment on the ground. Then, the collected data were automatically analyzed and calculated. The test data of the transmission accuracy, backlash, and transmission efficiency of the space harmonic reducer were obtained. It is proven by experiments that the performance data of the harmonic reducer in space work can be more accurately obtained by using the test system mentioned in this paper, which is convenient for further research on related lubricating materials.

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