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This article describes the equilibrium shape of a liquid drop under applied fields such as gravity and electrical fields, taking into account material properties such as dielectric constants, resistivities, and surface tension coefficients. The analysis is based on an energy minimization framework. A rigorous and exact link is provided between the energy function corresponding to any given physical phenomena, and the resulting shape and size dependent force term in Young’s equation. In particular, the framework shows that a physical effect, such as capacitive energy storage in the liquid, will lead to 1/R “line-tension”-type terms if and only if the energy of the effect is proportional to the radius of the liquid drop: E∝R. The effect of applied electric fields on shape change is analyzed. It is shown that a dielectric solid and a perfectly conducting liquid are all that is needed to exactly recover the Young–Lippmann equation. A dielectric liquid on a conducting solid gives rise to line tension terms. Finally, a slightly resistive liquid on top of a dielectric, highly resistive solid gives rise to contact angle saturation and accurately matches the experimental data that we observe in our electro-wetting-on-dielectric devices. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This article discusses and experimentally verifies how to lower the operating voltage that drives liquid droplets by the principle of electrowetting on dielectric (EWOD). A significant contact angle change (120°→80°) is desired to reliably pump the droplet in microchannels for applications such as lab-on-a-chip or micrototal analysis systems. Typically, much higher voltages (> 100 V) are used to change the wettability of an electrolyte droplet on a dielectric layer compared with a conductive layer. The required voltage can be reduced by increasing the dielectric constant and decreasing the thickness of the dielectric layer, thus increasing the capacitance of the insulating layer. This dependence of applied voltage on dielectric thickness is confirmed through EWOD experiments for three different dielectric materials of varying thickness: Amorphous fluoropolymer (Teflon® AF, Dupont), silicon dioxide (SiO[sub 2]) and parylene. The dependence on the dielectric constant is confirmed with two different dielectric materials of similar thickness: SiO[sup 2] and barium strontium titanate. In all cases, the surface is coated with a very thin (200 Å) layer of amorphous fluoropolymer to provide initial hydrophobicity. Limiting factors such as the dielectric breakdown and electrolysis are also discussed. By using very thin (700 Å) and high dielectric constant (∼180) materials, a significant contact angle change (120°→80°) has been achieved with voltages as low as 15 V. Based on these results, a microfluidic device has been fabricated and tested, demonstrating successful transporting (pumping) of a 460 nL water droplet with only 15 V. [ABSTRACT FROM AUTHOR]

Arthritis is a chronic inflammatory disease accompanied by pathological reactions such as swelling, redness, fever, and pain in various joint areas. The drugs currently available to treat arthritis are associated with diverse side-effects. Therefore, there is a need for safer and more effective treatments to alleviate the inflammation of arthritis with fewer side-effects. In this study, a new sterol, Δ8(14)-ergostenol, was discovered, and its glycosides were synthesized and found to be more efficient in terms of synthesis or anti-inflammatory activity than either spinasterol or 5,6-dihydroergosterol is. Among these synthetic glycosides, galactosyl ergostenol inhibited the expression of inflammatory mediators in TNF-α-stimulated FLS and TNF-α-induced MMPs and collagen type II A1 degradation in human chondrocytes. These results suggest the new galactosyl ergostenol as a treatment candidate for arthritis. [ABSTRACT FROM AUTHOR]

Atmospheric rivers (ARs) are elongated filaments of intense water vapor transport that occur mostly in the warm sector of an extratropical cyclone. ARs play crucial roles in the global as well as regional atmospheric water budget. Globally, ARs occur in less than 10% of the Earth's circumference but are responsible for nearly 90% of the total poleward water vapor transport in the middle latitudes. The intense water vapor fluxes of ARs are frequently related to the occurrence of hydrologic extremes in the region of AR landfalls. Because of their large impacts on the occurrence of extreme hydrologic events as well as on the atmospheric water budget, ARs have become a topic of intense research in recent years. Most of previous studies focus on the coastal regions of the eastern Pacific and the eastern Atlantic in winters because AR landfalls often cause massive flood damages in heavily developed regions in the west coast regions of North America and Europe. Recent progresses in identifying ARs using gridded data allow us to objectively analyze the relationship between water vapor fluxes and regional hydrologic characteristics, especially extreme events around the world. This study analyzes the climatology of AR and its impacts on precipitation and temperature in Korea using an IVT-based AR identification method. It is found that the East Asian coastal regions including Korea are among the most intense AR hot spots in the world. The AR frequency and the AR-related precipitation amounts in Korea undergo large seasonal cycles with the maximum (minimum) in summer (winter). The interannual variability of the AR frequency over Korea, measured in terms of the coefficient of variation, is slightly less than 1, about the same as in the west coast of the North America. The effects of ARs on temperature over Korea also vary according to seasons. AR landfalls are generally associated with anomalously warm days over Korea. The warm anomalies are larger for winter than for summer and increase towards the north. [ABSTRACT FROM AUTHOR]

In this study, O-glycosides of cholesterol derivatives Δ 7 -cholestenol and Δ 8(14) -cholestenol were prepared by Schmidt glycosylation with various glycosyl imidates. In addition, 1,2,3-triazole-linked N-glycosides of Δ 8(14) -cholestenol were prepared via the "click" reaction of proparzylic Δ 8(14) -cholestenol with glycosyl azides. The anti-inflammatory activities of these molecules were investigated for inhibitory mRNA expression activity of CCL17 and CCL22, which are important biomarkers of atopic dermatitis. Both the O- and N-glycosides Δ 7 -cholestenol and Δ 8(14) -cholestenol were observed to exhibit good anti-inflammatory activity in vitro. In particular, the 1,2,3-triazole-linked N-glycoside of Δ 8(14) -cholestenol exhibited anti-inflammatory activity similar to that of O-glycoside in vitro and is expected to be more potent in vivo due to better stability., (Copyright © 2022 Elsevier Inc. All rights reserved.)