A Study of Pressure Homogeneity in the Hexahedral Anvil High-Pressure Apparatus

1964 ◽  
Vol 86 (4) ◽  
pp. 729-735 ◽  
Author(s):  
G. A. Samara ◽  
A. Henius ◽  
A. A. Giardini
Keyword(s):  
High Pressure ◽  
Stress Distribution ◽  
Material Flow ◽  
Applied Load ◽  
Pressure Gradients ◽  
Operational Characteristics ◽  
Large Pressure ◽  
Heater Tube ◽  
High Pressure Apparatus ◽  
Increased Pressure

A study of operational characteristics and stress distribution in a large volume hexahedral apparatus has been made. Pyrophyllite containers with integral preformed gaskets were found to be superior to plain blocks. Pregasketing reduced material flow and sample deformation, increased by over 100 percent the central region of the container over which little or no deformation occurs, and greatly increased anvil life. Even so, large pressure gradients still existed within the container. These gradients become more severe the higher the pressure. Pressure efficiency and distribution were appreciably changed by varying the length and thickness of preformed gaskets. Built-in metal intensifiers increased pressure efficiency by up to 30 percent. The inclusion of a metal heater tube had no measurable influence on pressure gradients. Cycling decreased the applied load required to reach a given pressure only if the load was not allowed to fall below a certain minimum. This is attributed to the ability of pyrophyllite to remain static while supporting large stress gradients.

An absolute high-pressure microviscometer based on refractive index

1972 ◽  
Vol 331 (1585) ◽  
pp. 171-184 ◽  
Keyword(s):  
High Pressure ◽  
Refractive Index ◽  
Optical Constants ◽  
High Pressures ◽  
Point Contact ◽  
Viscosity Coefficient ◽  
Pressure Gradients ◽  
Viscosity Measurements ◽  
Large Pressure ◽  
Very High

A now method of measuring refractive index in a lubricant point contact is described which allows the density, pressure and viscosity in the fluid to be determined. The viscosity measurements are absolute, only the elastic and optical constants of the glass are needed. Due to the very high pressures developed (1 GPa) in the 0.3 mm diameter contact very large pressure gradients are produced, hence viscosities four orders higher than conventional high-pressure viscometers normally reach, can be measured. Four lubricants tested all showed that the pressure viscosity coefficient dropped sharply above 10 3 Pa s (10 4 poise); the limit of the normal viscometer. One fluid - a polyphenylether - apparently vitrified at high pressures to a limiting viscosity of 10 6 Pa s. Ball bounce is shown to limit the range of fluids that can be tested with this apparatus.

Pressure Gradients Affecting the Labyrinth during Hypobaric Pressure

1997 ◽  
Vol 106 (6) ◽  
pp. 495-502 ◽  
Author(s):  
Konrád S. Konrádsson ◽  
Björn I. R. Carlborg ◽  
Joseph C. Farmer
Keyword(s):  
Cerebrospinal Fluid ◽  
Eustachian Tube ◽  
Ambient Pressure ◽  
Pressure Gradients ◽  
Cochlear Aqueduct ◽  
Fluid Compartment ◽  
Large Pressure ◽  
Fluid Compartments ◽  
Pressure Changes ◽  
Considerable Pressure

Hypobaric effects on the perilymph pressure were investigated in 18 cats. The perilymph, tympanic cavity, cerebrospinal fluid, and systemic and ambient pressure changes were continuously recorded relative to the atmospheric pressure. The pressure equilibration of the eustachian tube and the cochlear aqueduct was studied, as well as the effects of blocking these channels. During ascent, the physiologic opening of the eustachian tube reduced the pressure gradients across the tympanic membrane. The patent cochlear aqueduct equilibrated perilymph pressure to cerebrospinal fluid compartment levels with a considerable pressure gradient across the oval and round windows. With the aqueduct blocked, the pressure decrease within the labyrinth and tympanic cavities was limited, resulting in large pressure gradients toward the chamber and the cerebrospinal fluid compartments, respectively. We conclude that closed cavities with limited pressure release capacities are the cause of the pressure gradients. The strain exerted by these pressure gradients is potentially harmful to the ear.

High-temperature calibration of a multi-anvil high pressure apparatus

2015 ◽  
Vol 35 (2) ◽  
pp. 139-147 ◽  
Author(s):  
Alexander G. Sokol ◽  
Yury M. Borzdov ◽  
Yury N. Palyanov ◽  
Alexander F. Khokhryakov
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Temperature Calibration ◽  
High Pressure Apparatus

scholarly journals Reactions under increased pressure: The reactivity of functionally substituted 3-oxo-2-arylhydrazones toward active methylene reagents in Q-tube

2021 ◽  
Vol 12 (2) ◽  
pp. 154-158
Author(s):  
Douaa Salman AlMarzouq
Keyword(s):  
High Pressure ◽  
Reaction Time ◽  
Reaction Times ◽  
Acid Ethyl Ester ◽  
One Pot ◽  
Two Component ◽  
Percentage Yield ◽  
Active Methylene ◽  
Total Reaction Time ◽  
Increased Pressure

A one-pot two-component reaction of 3-oxo-2-arylhydrazones with active methylene nitriles under high pressure in a Q-tube safe reactor was reported. Comparison between conventional and Q-tube safe reactor-assisted synthesis of organic compounds was done by comparing total reaction time and percentage yield. The results show that the compound 5-cyano-6-oxo-1,4-diphenyl-1,6-dihydro-pyridazine-3-carboxylic acid ethyl ester (3) was synthesized within 2 h in a yield of 97%. In addition, the pyrazolo[3,4-c]pyridines 5b and 5c were obtained in yields of 93 and 95% within 1 h reaction time, respectively. The obtained results suggest that Q-tube safe reactor-assisted syntheses were led to higher product yields within very short reaction times.

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