scholarly journals The persistence of the liquid state of aggregation above the critical temperature. The system ethylene

1937 ◽  
Vol 236 (766) ◽  
pp. 303-332 ◽  
Keyword(s):  
Critical Temperature ◽  
Hydrogen Chloride ◽  
Liquid State ◽  
Liquid Mixture ◽  
Molecular Compound ◽  
Continuous Change ◽  
Critical Temperatures ◽  
Component System ◽  
Rate Of Reaction ◽  
The Difference

The research described below arose from previous investigations carried out in this laboratory.* In a study of the influence of molecular compound formation on the rate of reaction (MAASS and SIVERTZ, 1925) it was found that although propylene and hydrogen chloride apparently react in a reproducible manner when the reactants are brought together in the liquid state, no measurable reaction occurs when they are brought together as gases. At first this was ascribed to the difference in concentration between the liquid and the gaseous states. However, it was shown (Sutherland and Maass, 1931) that when propylene and hydrogen chloride are brought together at room temperature as gases and heated above the critical temperatures of the mixture, no reaction occurs even when they are compressed to a concentration as great as that of the liquid mixture slightly below the critical temperature. The rate of reaction of the liquid mixture was found to increase with rise in temperature in the usual manner up to the critical temperature, but was found to be nil in the absence of the liquid phase. The acquirement of results of a similar nature by the application of the same procedure to other systems has been delayed owing to the fact that for most systems in which a homogeneous reaction takes place in the liquid state the critical temperatures and pressures are so high as to enhance greatly the experimental difficulties. An attempt to overcome these difficulties is still in progress. In the meantime other investigations have been undertaken with the object of finding a possible explanation for a discontinuity in reaction rate at the critical temperature. The first was an attempt to discover whether or not at the critical temperature a marked discontinuity of state exists in a two-component system, in contrast to the continuous change generally accepted as taking place in a one-component system.

PERSISTENCE OF THE LIQUID STATE OF AGGREGATION ABOVE THE CRITICAL TEMPERATURE

1938 ◽  
Vol 16b (9) ◽  
pp. 289-302 ◽  
Author(s):  
R. L. McIntosh ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Statistical Mechanics ◽  
Liquid State ◽  
Critical Pressure ◽  
Critical Density ◽  
Small Correction ◽  
Pressure Region ◽  
The Difference ◽  
Liquid States ◽  
Made In

The data obtained by Maass and Geddes (7) on the properties of ethylene in the critical-temperature–critical-pressure region have been substantiated although it was shown that a small correction had to be applied to their absolute values of density. It was shown that at the critical density of ethylene the difference between the densities of the medium below and above the point at which the meniscus disappeared was a maximum. The conclusion of Mayer and Harrison (made in their recent papers on statistical mechanics of condensing systems (6, 10)) that, at a temperature just above that at which the meniscus disappeared, the pressure of the system remains constant over a considerable variation of mass per volume, has been corroborated. The effect of the presence of small measured quantities of air has been examined. The phenomena observed are explained on the basis that there is a difference between the gaseous and liquid states of aggregation with a structure assigned to the latter.

AN INVESTIGATION OF THE HYDROGEN-CHLORIDE-PROPYLENE REACTION IN THE REGION OF THE CRITICAL TEMPERATURE

1938 ◽  
Vol 16b (12) ◽  
pp. 453-467 ◽  
Author(s):  
C. H. Holder ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Temperature Coefficient ◽  
Hydrogen Chloride ◽  
Liquid State ◽  
Critical Density ◽  
Positive Temperature ◽  
Gaseous State ◽  
Gaseous Mixtures ◽  
Reaction Velocity ◽  
Temperature Range

The reaction between hydrogen chloride and propylene has been studied in the gaseous state above the critical temperature and in the liquid state just below the critical temperature. Pressures were used such that the density of the gaseous mixtures could be made as great as the density of the liquid mixture at some temperature.The rate of reaction above the critical temperature increases slowly with increasing pressure until a certain critical density is attained, after which the rate increases rapidly. In the liquid state the reaction has a positive temperature coefficient except for a 25° temperature range just below the critical temperature. In this region there is a rapid decrease in density of the medium with rise in temperature and a negative temperature coefficient occurs.The density of the liquid reactants at a number of temperatures just below the critical temperature (here defined as the temperature where the visible meniscus disappears) has been reproduced above the critical temperature for a small temperature range. The reaction velocity data obtained under these conditions show a minimum in passing through the critical temperature region.The above results have been interpreted on the basis of a "structure" characteristic of the liquid state which favors higher reaction velocity and which may exist above the critical temperature at sufficiently high densities.

DENSITY-PRESSURE-TEMPERATURE RELATIONS OF THE HYDROGEN CHLORIDE-PROPYLENE SYSTEM IN THE CRITICAL TEMPERATURE-PRESSURE REGION. REACTION VELOCITY NEAR THE CRITICAL TEMPERATURE

1937 ◽  
Vol 15b (8) ◽  
pp. 345-351 ◽  
Author(s):  
C. H. Holder ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Hydrogen Chloride ◽  
Liquid State ◽  
Reaction Velocity ◽  
Temperature Range ◽  
Pressure Region

The relation between the density, pressure, and temperature of a 2:1 and of a 1:1 mixture of hydrogen chloride and propylene has been determined over the temperature range 78° to 115 °C. and up to pressures of 115 atm. These determinations are of interest in connection with the investigation of the influence of a "structure" of the liquid state on reaction velocity. Some preliminary measurements of reaction velocity in the critical temperature-pressure region have been made.

scholarly journals TEMPERATURE CHARACTERISTICS FOR PULSATION FREQUENCY IN GONIONEMUS

1928 ◽  
Vol 11 (5) ◽  
pp. 547-562 ◽  
Author(s):  
Ernst Wolf
Keyword(s):  
Critical Temperature ◽  
Functional Unit ◽  
Temperature Characteristic ◽  
Nerve Ring ◽  
Pulsation Frequency ◽  
Sense Organs ◽  
Critical Temperatures ◽  
Temperature Characteristics ◽  
System A ◽  
Definite Temperature

The frequency of contraction of the bell of Gonionemus was studied in relation to temperature, with intact animals and also where different operations were made on the nervous system. A number of values of µ are found for intact animals namely 8,100±, 10,500±, 32,000± and 22,500±, with critical temperatures at 9.6°, 12.3°, and 14.0°. Four different classes of operations were used: (1) Animals where the nerve ring was cut on two opposite sides of the bell; the µ values found are 10,500± and 21,300±, with a critical temperature at 13.4°. (2) Animals with four cuts through the nerve ring gave µ = 10,600 ± and µ = 21,000, with a critical temperature at 13.1°. (3) In animals where the bell was cut in half the temperature characteristic was found to be 16,900. And finally (4) in the animals where the nerve ring was totally removed µ values of 8,100, 16,000±, and 29,000 were found, with critical temperatures at 15.0° and 9.4°. These results are discussed from the standpoint of the theory which supposes that definite "temperature characteristics" may be associated with the functional activity of particular elements in a complex functional unit, and that these elements may be separately studied and identified by suitable experimental procedures involving the magnitudes of the respective temperature characteristics and the locations of associated critical temperatures. The swimming bell of medusæ with its marginal sense organs permits a fairly direct approach to such questions. It is found that even slight injuries to the marginal nerve ring, for example, produce specific modifications in the temperature relations which are different from those appearing when the organism is cut in half.

DENSITY DISCONTINUITIES AT THE CRITICAL TEMPERATURE

1933 ◽  
Vol 9 (6) ◽  
pp. 613-629 ◽  
Author(s):  
C. A. Winkler ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Small Region ◽  
Density Difference ◽  
Experimental Investigations ◽  
Sharp Change ◽  
Two Component System ◽  
Medium Increase ◽  
The Difference ◽  
Temperature Equilibrium ◽  
Continuous Relation

A technique for measuring densities in various parts of a one- or two-component system, raised above its critical temperature, is described. Considerable improvements over a method for this purpose recently described by one of the writers consist in greater flexibility of manipulation and in making possible a variation in the volume of space confining the medium during the experiment. Propylene and methyl-ether were the two media examined. From the results the following generalizations regarding aberrations from the continuity of state were found to hold for both.When either liquid was heated above the temperature at which the visible meniscus disappeared, the density below this point of disappearance was found to be greater than that above. The density was uniform throughout each portion, undergoing a relatively sharp change in the small region where the meniscus was last seen. After one hour of temperature equilibrium, the difference in density between top and bottom became constant and remained unaltered for six hours. Constant stirring or temperature fluctuations of the order of 0.02 °C. do not alter this density difference. A decrease in the volume available for the medium increases the density difference between the top and bottom, a continuous relation existing between available space and density difference. With decrease in available space, the densities of both upper and lower portions of the medium increase, the density of the lower more rapidly than that of the upper. These results were reproducible quantitatively in the experiments carried out to date. The density difference for a fixed available space decreases with rise in temperature and is measurable up to at least 10 °C. above the critical temperature. A number of miscellaneous experiments are described which form the basis of work now being carried out. The theoretical significance of aberrations from the continuity of state is discussed to the extent warranted by the present stage of the experimental investigations, and tentative conclusions are drawn.

Crystalline-To-Amorphous Transformation of Intermetallic Compounds in the Zr-Fe-M System Induced by Irradiation

1994 ◽  
Vol 373 ◽  
Author(s):  
Arthur T. Motta ◽  
Lawrence M. Howe ◽  
Paul R. Okamoto
Keyword(s):  
Critical Temperature ◽  
Low Temperature ◽  
Dose Rate ◽  
Intermetallic Compounds ◽  
Electron Energy ◽  
Energy Dependence ◽  
Electron Irradiation ◽  
Critical Temperatures ◽  
Lower Critical Temperature ◽  
Ternary Intermetallic Compounds

AbstractThe binary and ternary intermetallic compounds Zr3Fe, Zr2 Fe, (Zr0.5,Nb0.5)3Fe, Zr3(Fe0.9,Ni0.1) and Zr3(Fe0.5,Ni0.5) were subjected to 900 keV electron irradiation until amorphous to study the change in the dose-to-amorphization with temperature. The critical temperatures were observed to vary with dose rate, and with the type of compound. Hexagonal (Zr0.5,Nb0.5)3Fe had an appreciably lower critical temperature and higher dose to amorphization at low temperature than orthorombic Zr3Fe, whereas other orthorombic Zr3(Fex,NiI-x) compounds were essentially identical in behavior to Zr3Fe. The electron energy dependence of the dose-to-amorphization was studied in Zr3Fe between 250 and 900 keV. The analysis of the results gives displacement energies of EZrd = 26 eV, EFed = 18 eV in the Zr3Fe compound.

scholarly journals Strong correlation between electronic bonding network and critical temperature in hydrogen-based superconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Belli ◽  
Trinidad Novoa ◽  
J. Contreras-García ◽  
Ion Errea
Keyword(s):  
Critical Temperature ◽  
Physical Properties ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
Strong Correlation ◽  
Critical Temperatures ◽  
Structural And Electronic Properties ◽  
Superconducting Compounds ◽  
Better Than

AbstractBy analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity of creating an electronic bonding network between localized units is key to enhance the critical temperature in hydrogen-based superconductors. We define a magnitude named as the networking value, which correlates with the predicted critical temperature better than any other descriptor analyzed thus far. By classifying the studied compounds according to their bonding nature, we observe that such correlation is bonding-type independent, showing a broad scope and generality. Furthermore, combining the networking value with the hydrogen fraction in the system and the hydrogen contribution to the density of states at the Fermi level, we can predict the critical temperature of hydrogen-based compounds with an accuracy of about 60 K. Such correlation is useful to screen new superconducting compounds and offers a deeper understating of the chemical and physical properties of hydrogen-based superconductors, while setting clear paths for chemically engineering their critical temperatures.

scholarly journals Facilitating Organizational Unlearning using Appreciative Inquiry as an Intervention

2009 ◽  
Vol 34 (4) ◽  
pp. 67-78 ◽  
Author(s):  
T M Srithika ◽  
Sanghamitra Bhattacharyya
Keyword(s):  
Organizational Learning ◽  
Organizational Development ◽  
Appreciative Inquiry ◽  
Diagnostic Process ◽  
Continuous Change ◽  
Change Initiatives ◽  
Diagnostic Problem Solving ◽  
Cognitive Behavioural ◽  
Strength Based ◽  
The Difference

Drawing upon theoretical bases, this paper attempts to demonstrate a relationship between Appreciative Inquiry (AI), an organizational development (OD) intervention, and organizational unlearning. Present day organizations are characterized by continuous change. It has been accepted that change implies learning along various dimensions: cognitive, behavioural, and normative. Any type of organizational learning would involve: (1) creation of new knowledge and (2) getting rid of obsolete knowledge. The first aspect refers to learning while the second aspect relates to unlearning. While literature abounds in studies pertaining to organizational learning, literature on organizational unlearning is relatively few and far between. While appreciating the fact that both learning and unlearning complement each other and result in change, this paper has attempted to highlight the difference that inherently exists in the process of unlearning, as compared to the process of learning. And it is on account of these differences that the techniques or interventions that facilitate organizational learning may not be appropriate for organizational unlearning. According to Zell (2003), increased resistance to unlearn exists for individuals, groups or organizations due to their fear of loss of time and resources invested earlier in gaining such knowledge. Senge (1990) has described how the diagnostic process of analysing problems and identifying solutions by itself stifles creativity and flexibility and increases resistance. Thus, increased resistance and fear inherent in the unlearning process calls for an affirmative and strength-based approach such as Appreciative Inquiry, vis-a-vis other diagnostic problem-solving interventions. Based on an extensive review of existing literature, this paper attempts to demonstrate how AI can be used as an effective facilitator for unlearning. The complete AI process and principles have been enumerated and mapped to the unlearning process. With an eye to objectivity, the authors have also attempted to identify inhibiting factors that might hinder the process of unlearning while using AI as an intervention. While adding to existing literature, this paper is also expected to contribute meaningfully by sensitizing practising managers about this technique and logically establishing its efficacy, along with awareness creation of possible challenges that might arise during intervention. This in turn can have significant implications for longterm organizational change initiatives and OD practices.

Thermodynamic of the charged AdS black holes in Rastall gravity: P − V critical and Joule–Thomson expansion

2020 ◽  
Vol 35 (14) ◽  
pp. 2050113
Author(s):  
Sen Guo ◽  
Yan Han ◽  
Guo Ping Li
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Critical Temperature ◽  
Critical Exponents ◽  
State Equation ◽  
The State ◽  
Thermodynamic Quantities ◽  
Critical Temperatures ◽  
Ads Black Holes ◽  
And Inversion

In this paper, we study the thermodynamic of the charged AdS black holes in Rastall gravity. Firstly, the thermodynamic quantities of the charged AdS black holes in Rastall gravity are reviewed and the state equation of this black hole is obtained. Then, we investigate the [Formula: see text] critical and the Joule–Thomson expansion of the charged AdS black holes in Rastall gravity in which the critical temperature and the critical exponents are obtained. In addition, we get the inversion temperature and plot the isenthalpic and inversion curves in the [Formula: see text] plane, and also determine the cooling-heating regions of this black hole through the Joule–Thomson expansion. Finally, we investigate the ratio between the minimum inversion and critical temperatures, and find that the Rastall constant [Formula: see text] does not affect of this ratio.

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