THE EFFECT OF PRESSURE ON THE REDUCTION OF PORE VOLUME OF CONSOLIDATED SANDSTONES

Geophysics ◽  
1953 ◽  
Vol 18 (2) ◽  
pp. 298-309 ◽  
Author(s):  
D. S. Hughes ◽  
C. E. Cooke
Keyword(s):  
Hydrostatic Pressure ◽  
Pore Volume ◽  
Room Temperature ◽  
Pressure Coefficient ◽  
Berea Sandstone ◽  
Total Change ◽  
Effect Of Pressure ◽  
Percent Change ◽  
Pressure Changes

The changes in pore volume of jacketed dry sandstone samples have been measured under hydrostatic pressures over the range 50 to 1,000 bars (14,504 psi). The percent change in pore volume at each pressure and the pressure coefficient of change of pore volume have been computed. All measurements were made at room temperature. The total change in pore volume when the hydrostatic pressure was increased from 50 to 1,000 bars was found to be about 7.5 percent of the pore volume for a sample of Steven sandstone (porosity 18.5 percent) and approximately 3.0 percent of the pore volume for a sample of Berea sandstone (porosity 19.4 percent). The coefficient of change of pore volume with pressure is found to decrease rather rapidly with increasing pressure up to around 500 bars. Thus pressure changes applied to rock become much more important when the original geostatic load on the rock is small.

THE EFFECT OF PRESSURE ON THE ELECTRICAL RESISTANCE OF LITHIUM

1963 ◽  
Vol 41 (8) ◽  
pp. 1381-1384 ◽  
Author(s):  
D. Gugan
Keyword(s):  
Hydrostatic Pressure ◽  
Electrical Resistance ◽  
Low Temperatures ◽  
Pressure Coefficient ◽  
Residual Resistivity ◽  
Effect Of Pressure ◽  
Dilute Alloys

The change of resistance of lithium with hydrostatic pressure has been studied at low temperatures. Anomalous results have been found at all temperatures. The pressure coefficient of residual resistivity of dilute alloys of magnesium in lithium has been found to depend on the structure of the parent lattice.

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

The effects of osmotic pressure changes on the germination of Dictyostelium discoideum spores

1977 ◽  
Vol 23 (9) ◽  
pp. 1170-1177 ◽  
Author(s):  
David A. Cotter
Keyword(s):  
Ethylene Glycol ◽  
Dictyostelium Discoideum ◽  
Room Temperature ◽  
Thermal Inactivation ◽  
Sucrose Concentration ◽  
Lag Phase ◽  
Activation Process ◽  
Sucrose Solutions ◽  
Spore Population ◽  
Pressure Changes

Polyalcohols such as ethylene glycol and glycerol at 3 M penetrate and activate spores of Dictyostelium discoideum incubated at room temperature. Higher concentrations of ethylene glycol result in lysis upon suspension of spores in dilute phosphate buffer. Erythritol and arabitol at 3 M do not penetrate or activate D. discoideum spores.Air-dried spores or those incubated in 2 M sucrose solutions are not activated with the usual heat treatment of 45 °C for 30 min. The plasmolyzed spores are activated at temperatures above 45 °C when heated in the presence of 2 M sucrose for 30 min. The temperature for maximum activation and the temperature for thermal inactivation of spores are raised 7–10 °C in high sucrose concentrations. Long-term incubation of heat-activated spores in 2 M sucrose solutions does not result in a return to dormancy.Moderate sucrose concentrations near 0.2 M do not block the heat-induced activation process but must be removed from the spore population to prevent a return to dormancy within 6 h. Other polyhydric compounds at 0.25 M concentration also cause spore deactivation within 6 h of room temperature incubation. Oxygen uptake of spores undergoing deactivation in 0.18 M sucrose is inhibited as compared to control levels. Moderate concentrations of sucrose do not block the early events of postactivation lag and the spores accumulate at the end of the lag phase. The longer the spores remain unswollen at the end of the postactivation lag phase, the greater the percentage of spores which return to dormancy. The effects of moderate sucrose concentration (lowered water activity) are not duplicated by the same quantity of Ficoll, indicating that the colligative properties of the sucrose solutions are responsible for deactivation.

Glass Transition of LDPE and PP under High Quasi-Hydrostatic Pressure in Room Temperature

2021 ◽  
Author(s):  
Chaohu Yu ◽  
Yewen Zhang ◽  
Jingxian Xu ◽  
Yabo Sun ◽  
Zhi Li ◽  
...  
Keyword(s):  
Glass Transition ◽  
Hydrostatic Pressure ◽  
Room Temperature

scholarly journals Aerodynamic Phenomena Caused by the Passage of a Train. Part 2: Pressure Influence on Passing Trains

2021 ◽  
Vol 65 (192) ◽  
pp. 195-202
Author(s):  
Andrzej Zbieć
Keyword(s):  
High Speed ◽  
Rolling Stock ◽  
Literature Analysis ◽  
High Speed Railway ◽  
Railway Vehicles ◽  
Effect Of Pressure ◽  
Pressure Changes

In the series of articles describing the aerodynamic phenomena caused by the passage of a train, the effects of a train running at high speed on itself, on other trains, on objects on the track and on people are characterized. This impact can be of two types – generated pressure and slipstream. Apart from the literature analysis, the author’s research is also taken into account. The second part presents the effect of pressure changes on the front and side surfaces of passing trains. Conclusions concerning side windows and windscreens in high-speed railway vehicles and older type railway vehicles with lower allowable speeds and the possibility of using various rolling stock on the same lines are presented. Keywords: rolling stock, high-speed railways, aerodynamic phenomena

Effect of Hydrostatic Pressure on Geometry of Slip in Silicon Iron Single Crystals

1983 ◽  
Vol 22 ◽  
Author(s):  
A.V. Dobromyslov ◽  
G.V. Dolgikh ◽  
N.I. Talutz ◽  
V.T. Shmatov ◽  
B. I. Beresnev
Keyword(s):  
Hydrostatic Pressure ◽  
Single Crystals ◽  
Slip Plane ◽  
Special Structure ◽  
Normal Stresses ◽  
Silicon Iron ◽  
Screw Dislocations ◽  
Effect Of Pressure ◽  
Effect Of Hydrostatic Pressure

ABSTRACTThe effect of the pressure 550MPa on the choice of the acting slip plane in the single crystals of Fe−2,9%Si was studied. It was established that the presence of pressure resulted in the increase of the slip asymmetry. The effect of pressure is attributed to the action of normal stresses and to the special structure of screw dislocations.

scholarly journals Parathormone stability in hemodialyzed patients and healthy subjects: comparison on non-centrifuged EDTA and serum samples with second- and third-generation assays

2017 ◽  
Vol 55 (8) ◽  
pp. 1152-1159 ◽  
Author(s):  
Marie-Louise Schleck ◽  
Jean-Claude Souberbielle ◽  
Pierre Delanaye ◽  
Mario Plebani ◽  
Etienne Cavalier
Keyword(s):  
Healthy Subjects ◽  
Room Temperature ◽  
Wilcoxon Test ◽  
Dialysis Session ◽  
Third Generation ◽  
Serum Samples ◽  
Total Change ◽  
Edta Plasma ◽  
Calcium Measurement ◽  
Single Batch

Abstract Background: Parathyroid hormone (PTH) stability is important. Many studies have shown divergent results between EDTA and serum, which are mainly linked to differences in protocols or cut-offs used to determine whether or not PTH remained stable. No studies have yet compared PTH stability as measured by second- and third-generation assays on the same samples in hemodialyzed patients and healthy subjects. Methods: Five pairs of samples (EDTA and gel tubes) were obtained in 10 hemodialyzed patients before a dialysis session and in 10 healthy subjects. One pair was centrifuged and run directly to define the “T0”. Two pairs were kept at +4°C and two pairs were kept at +25°C. They were centrifuged after 4 and 18 h. Supernatant was kept at –80°C for 1 week. All samples were measured in a single batch, on Roche Cobas and DiaSorin XL second- and third-generation PTH assays. We used three different approaches to evaluate PTH stability: Wilcoxon test, an Acceptable Change Limit (ACL) according to ISO Guide 5725-6 and a Total Change Limit (TCL) derived from the sum of biological and technical variability according to WHO. Results: PTH decreased in all samples. Stability of PTH was mainly dependent on the way it was evaluated. Percentages of decrease were systematically lower in EDTA vs. serum. Wilcoxon and ACL showed that PTH was no more stable after 4 h at +4°C in EDTA or serum gel tubes. None of the subjects presented a PTH decrease higher than the TCL with EDTA plasma. In serum gel tubes, PTH was unstable only when kept at 25°C for 18 h. Conclusions: PTH seems more stable in EDTA than in serum gel tubes but only when samples have to stay unprocessed for a long period (18 h) at room temperature (25°C), which can happen when samples are delivered from external care centers. For all the other conditions, using serum gel tubes is recommended since calcium measurement, which is necessary for a good PTH results interpretation, can be achieved on the same tube.

The Distribution of P O2 and Hydrostatic Pressure Changes Within the Branchial Chambers in Relation to GILL VENTILATION OF THE SHORE CRAB CARCINUS MAENAS L

1969 ◽  
Vol 51 (1) ◽  
pp. 203-220
Author(s):  
G. M. HUGHES ◽  
B. KNIGHTS ◽  
C. A. SCAMMELL
Keyword(s):  
Hydrostatic Pressure ◽  
Ventilation System ◽  
Carcinus Maenas ◽  
Pressure Change ◽  
Shore Crab ◽  
Positive Pressure ◽  
Transparent Plastic ◽  
Gill Lamellae ◽  
Minimum Disturbance ◽  
Pressure Changes

1. A technique is described for replacing part of the branchiostegite of Carcinus maenas by a transparent plastic ‘window’ for direct observation of the gills in situ with minimum disturbance. 2. Observation of dye streams shows that most water enters the hypobranchial space through the Milne-Edwards openings above the chelae, flowing anteriorly and/or posteriorly to ventilate most of gills 3-8. Water also enters above the pereiopods to ventilate the rest of the gills. Water passes from the hypobranchial to the epibranchial space, confirming that there is a counterflow with respect to the circulation of blood through the gill lamellae. 3. By sampling water at different points in the branchial system, patterns of oxygen removal were studied. The gradients confirmed the direction of water flow observed by the use of dyes. 4. Rhythmic changes in hydrostatic pressure in normal forward-pumping of 3-12 mm. H2O were recorded from the branchial cavities, superimposed on a maintained negative pressure relative to that outside the crab of 0-10 mm. H2O. Reversals produced a brief positive pressure change of 0-22 mm. H2O. 5. The possible relationships of the rhythmic pressure changes to scaphognathite movements are discussed. 6. The role of reversals is discussed and it is concluded that their primary function during ventilation is in helping to clean the ventrally facing gill surfaces. But they are also important in respiration under certain special conditions which arise during the normal life of the animal. 7. The utilization of O2 during its passage over the gills is low (7-23%) in spite of the counterflow. Possible explanations of this are discussed in relation to a model of the whole ventilation system.

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