Effect of Direct Current on Interfacial Tension of Condensate Droplet Immersed in Brine

The effect of direct current (DC) on the wetting behavior of Cu substrate by liquid Ga–25In–13Sn alloy at room temperature is investigated using a sessile drop method. It is found that there is a critical value for current intensity, below which the decrease of contact angle with increasing current intensity is approximately linear and above which contact angle tends to a stable value from drop shape. Current polarity is a negligible factor in the observed trend. Additionally, the observed change in contact angles is translated into the corresponding change in solid-liquid interfacial tension using the equation of state for liquid interfacial tensions. The solid-liquid interfacial tension decreases under DC. DC-induced promotion of solute diffusion coefficient is likely to play an important role in determining the wettability and solid-liquid interfacial tension under DC.

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Manipulation of single sub-femtolitre droplets via partial coalescence in a direct-current electric field

Flow ◽

10.1017/flo.2021.12 ◽

2021 ◽

Vol 1 ◽

Author(s):

Mostafa Shojaeian ◽

Steffen Hardt

Keyword(s):

Electric Field ◽

Interfacial Tension ◽

Direct Current ◽

Applied Electric Field ◽

Reciprocating Motion ◽

Partial Coalescence ◽

Direct Current Electric Field ◽

Underlying Principle ◽

Before And After ◽

Current Electric Field

Abstract It is demonstrated how aqueous droplets with volumes down to the sub-femtolitre range can be manipulated, including the withdrawal of minute samples from the droplets. The underlying principle is that of partial coalescence with a liquid reservoir in an applied electric field. Upon partial coalescence, a droplet merges with a reservoir and reappears with a smaller diameter. The droplets studied here perform a reciprocating motion between two reservoirs during which their volume gets reduced. Manipulation of droplets with diameters down to 400 nm is reported. A similarity relation is derived expressing the ratio of droplet diameters before and after partial coalescence as a function of the ratio between electric and interfacial-tension forces. The presented scheme allows the withdrawal of minute samples from small droplets and could prove helpful in various applications where droplets are used as tiny reaction spaces or when the goal is to tailor the size of individual droplets.

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Effect of direct current on gas condensate droplet immersed in brine solution

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01184-4 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2845-2860

Author(s):

Princewill M. Ikpeka ◽

Johnson O. Ugwu ◽

Gobind G. Pillai ◽

Paul Russell

Keyword(s):

Interfacial Tension ◽

Oil Recovery ◽

Electrical Current ◽

Gas Condensate ◽

Displacement Efficiency ◽

Electric Voltage ◽

Gas Condensate Reservoirs ◽

Droplet Movement ◽

Droplet Trajectory ◽

Condensate Droplet

AbstractEnvironmentally sustainable methods of extracting hydrocarbons from the reservoir are increasingly becoming an important area of research. Several methods are being applied to mitigate condensate banking effect which occurs in gas condensate reservoirs; some of which have significant impact on the environment (subsurface and surface). Electrokinetic enhanced oil recovery (EEOR) increases oil displacement efficiency in conventional oil reservoirs while retaining beneficial properties to the environment. To successfully apply this technology on gas condensate reservoirs, the behavior of condensate droplets immersed in brine under the influence of electric current need to be understood. A laboratory experiment was designed to capture the effect of electrical current on interfacial tension and droplet movement. Pendant drop tensiometry was used to obtain the interfacial tension, while force analysis was used to analyze the effect of the electrical current on droplet trajectory. Salinity (0–23 ppt) and electric voltage (0–46.5 V) were the main variables during the entire experiment. Results from the experiment reveal an increase in IFT as the voltage is increased, while the droplet trajectory was significantly altered with an increase in voltage. This study concludes that the interfacial tension increases progressively with an increase in DC current, until its effect counteracts the benefit obtained from the preferential movement of condensate droplet.

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ECG changes after direct current cardioversion of atrial fibrillation by the transthoracic and transvenous routes

Journal of Cardiothoracic and Vascular Anesthesia ◽

10.1016/s1053-0770(98)90291-9 ◽

1998 ◽

Vol 31 ◽

pp. 69

Author(s):

M HARBINSON

Keyword(s):

Atrial Fibrillation ◽

Direct Current ◽

Ecg Changes ◽

Direct Current Cardioversion

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Inter-Method Reliability of Pulse Volume Related Measures Derived Using Finger-Photoplethysmography

Journal of Psychophysiology ◽

10.1027/0269-8803/a000197 ◽

2018 ◽

Vol 32 (4) ◽

pp. 182-190 ◽

Cited By ~ 4

Author(s):

Kenta Matsumura ◽

Koichi Shimizu ◽

Peter Rolfe ◽

Masanori Kakimoto ◽

Takehiro Yamakoshi

Keyword(s):

Light Intensity ◽

Adverse Effects ◽

Light Source ◽

Direct Current ◽

Resting State ◽

Current Component ◽

Psychophysiological Measures ◽

Pulse Volume ◽

Optical Paths ◽

Sensor Positions

Abstract. Pulse volume (PV) and its related measures, such as modified normalized pulse volume (mNPV), direct-current component (DC), and pulse rate (PR), derived from the finger-photoplethysmogram (FPPG), are useful psychophysiological measures. Although considerable uncertainties exist in finger-photoplethysmography, little is known about the extent of the adverse effects on the measures. In this study, we therefore examined the inter-method reliability of each index across sensor positions and light intensities, which are major disturbance factors of FPPG. From the tips of the index fingers of 12 participants in a resting state, three simultaneous FPPGs having overlapping optical paths were recorded, with their light intensity being changed in three steps. The analysis revealed that the minimum values of three coefficients of Cronbach’s α for ln PV, ln mNPV, ln DC, and PR across positions were .948, .850, .922, and 1.000, respectively, and that those across intensities were .774, .985, .485, and .998, respectively. These findings suggest that ln mNPV and PR can be used for psychophysiological studies irrespective of minor differences in sensor attachment positions and light source intensity, whereas and ln DC can also be used for such studies but under the condition of light intensity being fixed.

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