The Experimental Hydration of Obsidian as a Function of Relative Humidity and Temperature

1991 ◽  
Vol 56 (3) ◽  
pp. 504-513 ◽  
Author(s):  
J. J. Mazer ◽  
C. M. Stevenson ◽  
W. L. Ebert ◽  
J. K. Bates
Keyword(s):  
Relative Humidity ◽  
Driving Force ◽  
Rate Increase ◽  
Chemical Potential ◽  
Water Diffusion ◽  
Potential Difference ◽  
Molecular Water ◽  
Chemical Potential Difference ◽  
Isothermal Conditions ◽  
Age Estimates

The experimental hydration of obsidian for up to 30 days is described at relative humidities (RH) of 60, 90, 95, and 100 percent and at temperatures of 150, 160, and 175°C. Under isothermal conditions, the rate of hydration increased by as much as 25 percent between 60 and 100 percent RH. The RH dependence is nonlinear, with the majority of the rate increase occurring between 90 and 100 percent RH. The effect of RH can be related to the driving force for molecular water diffusion in obsidians as described by the chemical potential difference between water sorbed onto the obsidian surface and intrinsic water in the obsidian. The differences in hydration rates caused by RH differences in experiments approximate the error commonly described for obsidian-hydration dating. These results suggest that obsidian-hydration dating requires a knowledge of the site temperature and relative humidity in order to accurately generate age estimates.

DYNAMICAL MODES OF POLYMER TRANSLOCATING THROUGH INTERACTING PORE UNDER CHEMICAL POTENTIAL DIFFERENCE

2011 ◽  
Vol 25 (25) ◽  
pp. 3345-3351 ◽  
Author(s):  
WEI-PING CAO ◽  
LI-ZHEN SUN ◽  
CHAO WANG ◽  
MENG-BO LUO
Keyword(s):  
Monte Carlo ◽  
Polymer Chain ◽  
Power Law ◽  
Chemical Potential ◽  
Monte Carlo Technique ◽  
Potential Difference ◽  
Nonequilibrium Process ◽  
Chemical Potential Difference ◽  
Translocation Time

The translocation of polymer chain through an interacting pore under chemical potential difference Δμ is simulated using Monte Carlo technique. Three translocation modes, dependent on the polymer–pore interaction ε and Δμ, are discovered. The translocation process is found to be an nonequilibrium process, which influences the dependence of translocation time τ on ε and Δμ. It is found that τ decreases in a power law relation with the increase of Δμ, and the exponent is dependent on the interaction.

scholarly journals Nonequilibrium Thermodynamic Analysis of the Coupling between Active Sodium Transport and Oxygen Consumption

1974 ◽  
Vol 64 (3) ◽  
pp. 372-391 ◽  
Author(s):  
G. Danisi ◽  
F. Lacaz Vieira
Keyword(s):  
Oxygen Consumption ◽  
Sodium Transport ◽  
Chemical Potential ◽  
Nonequilibrium Thermodynamic ◽  
Potential Difference ◽  
Stoichiometric Ratio ◽  
Active Sodium ◽  
Na Transport ◽  
Chemical Potential Difference ◽  
Active Sodium Transport

Sodium transport and oxygen consumption have been simultaneously studied in the short-circuited toad skin. A constant stoichiometric ratio was observed in each skin under control condition (NaCl-Ringer's solution bathing both sides of the skin) and after block of sodium transport by ouabain. During alterations of sodium transport by removal and addition of K to the internal solution the stoichiometric ratio is constant although having a value higher than that observed in other untreated skins. The coupling between active sodium transport and oxygen consumption was studied after a theoretical nonequilibrium thermodynamic model. Studies were made of the influence of Na chemical potential difference across the skin on the rates of Na transport and oxygen consumption. A linear relationship was observed between the rates of Na transport and oxygen consumption and the Na chemical potential difference. Assuming the Onsager relationship to be valid, the three phenomenological coefficients which describe the system were evaluated. Transient increases in the rate of sodium transport and oxygen consumption were observed after a transitory block of sodium transport by removal of Na from the external solution. Cyanide blocks completely the rate of oxygen consumption in less than 2 min and the short-circuit current measured after that time decays exponentially with time, suggesting a depletion of ATP from a single compartment.

ELECTRO-CHEMICAL POTENTIAL DIFFERENCE VARIATION BY PULSED ULTRASOUND

1987 ◽  
pp. 589-593
Author(s):  
G.K. Johri ◽  
N.V. Dezhkunov ◽  
G. Iernetti ◽  
P. Ciuti ◽  
A. Francescutto
Keyword(s):  
Chemical Potential ◽  
Potential Difference ◽  
Pulsed Ultrasound ◽  
Chemical Potential Difference

A Study on Rolling Element Skew Measurement in a Tapered Roller Bearing With a Specialized Capacitance Probe

1999 ◽  
Vol 122 (3) ◽  
pp. 534-538 ◽  
Author(s):  
Yeyuan Yang ◽  
Steven Danyluk ◽  
Michael Hoeprich
Keyword(s):  
Rotational Speed ◽  
Chemical Potential ◽  
Contact Potential Difference ◽  
Roller Bearing ◽  
Potential Difference ◽  
Chemical Potential Difference ◽  
Contact Potential ◽  
Tapered Roller Bearing ◽  
Capacitance Probe ◽  
Tapered Roller

This paper reports on roller skew in tapered roller bearings. The roller skewing of a tapered roller bearing is experimentally measured with a specialized capacitance probe (Kelvin contact potential difference, CPD, probe). The probe measures the electro-chemical potential difference between the probe and roller surfaces. Two probes are inserted through holes in the housing and bearing outer race. The electrical signals from both ends of a roller are used to determine the skewing. The technique, as well as the effect of lubrication and rotational speed on the roller skewing, is presented. It is shown that the skewing increases with an increase in rotational speed, and the lubrication of the large end of the roller. A theoretical analysis has been developed to account for the experimental results. [S0742-4787(00)01803-8]

Potential Differences Across Natural Membranes Separating Unlike Salt Solutions

1931 ◽  
Vol 8 (2) ◽  
pp. 124-132
Author(s):  
S. C. BROOKS ◽  
A. C. GIESE ◽  
R. I. GIESE
Keyword(s):  
Calcium Ion ◽  
Cell Walls ◽  
Chemical Potential ◽  
Potential Difference ◽  
Alkali Metal Cations ◽  
Lower Epidermis ◽  
Salt Solutions ◽  
Chemical Potential Difference ◽  
Concentration Potential ◽  
Bioelectric Potentials

1. When the lower epidermis of the bulb scale of the onion separates 0.1M and 0.01M solutions of KCl, NaCl, or LiCl a transient "concentration" potential difference was observed, whose magnitude decreased in the order: K > Na > Li. 2. The potential difference of 0.1M: 0.01M CaCl2 is small and opposite in sign to that of the above chains. 3. When the epidermis separates like concentrations of chlorides of K, Na, and Li a cation "chemical" potential difference arises which is low but steady. 4. When K-salts with different anions are present on the opposite sides of the membrane, the anion "chemical" potential difference is small or lacking. 5. These facts are most simply accounted for by assuming that the epidermis is a mosaic of cation and anion permeable areas, the permeability to alkali metal cations much exceeding that for calcium ion or the anions tried. 6. It is pointed out that the cell walls may perhaps participate in the production of the bioelectric potentials observed in other plants.

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