Size-Selective Sliding of Sessile Drops on a Slightly Inclined Plane Using Low-Frequency AC Electrowetting

When placed on an inclined solid plane, drops often stick to the solid surface due to pinning forces caused by contact angle hysteresis. When the drop size or the plane’s incline angle is small, the drop is difficult to slide due to a decrease in gravitational force. Here we demonstrate that small drops (0.4–9 μL) on a slightly inclined plane (∼12°, Teflon and parylene-C surface) can be mobilized through patterned electrodes by applying low-frequency ac electrowetting under 400 Hz (110–180 V_rms), which has a mechanism different from that of the high-frequency ac method that induces sliding by reducing contact angle hysteresis. We attribute the sliding motion of our method to a combination of contact angle hysteresis and interfacial oscillation driven by ac electrowetting instead of the minimization of contact angle hysteresis at a high frequency. We investigated the effects of ac frequency on the sliding motion and terminal sliding of drops; the terminal sliding velocity is greatest at resonance frequency. Varying the electrowetting number (0.21–0.56) at a fixed frequency (40 Hz) for 5 μL drops, we found an empirical relationship between the electrowetting number and the terminal sliding velocity. Using the relationship between the drop size and ac frequency, we can selectively slide drops of a specific size or merge two drops along an inclined plane. This simple method will help with constructing microfluidic platforms with sorting, merging, transporting, and mixing of drops without a programmable control of electrical signals. Also, this method has a potential in heat transfer applications because heat removal capacity can be enhanced significantly through drop oscillation

Size-Selective Sliding of Sessile Drops on a Slightly Inclined Plane Using Low-Frequency AC Electrowetting

When placed on an inclined solid plane, drops often stick to the solid surface due to pinning forces caused by contact angle hysteresis. When the drop size or the plane’s incline angle is small, the drop is difficult to slide due to a decrease in gravitational force. Here we demonstrate that small drops (0.4–9 μL) on a slightly inclined plane (∼12°, Teflon and parylene-C surface) can be mobilized through patterned electrodes by applying low-frequency ac electrowetting under 400 Hz (110–180 V_rms), which has a mechanism different from that of the high-frequency ac method that induces sliding by reducing contact angle hysteresis. We attribute the sliding motion of our method to a combination of contact angle hysteresis and interfacial oscillation driven by ac electrowetting instead of the minimization of contact angle hysteresis at a high frequency. We investigated the effects of ac frequency on the sliding motion and terminal sliding of drops; the terminal sliding velocity is greatest at resonance frequency. Varying the electrowetting number (0.21–0.56) at a fixed frequency (40 Hz) for 5 μL drops, we found an empirical relationship between the electrowetting number and the terminal sliding velocity. Using the relationship between the drop size and ac frequency, we can selectively slide drops of a specific size or merge two drops along an inclined plane. This simple method will help with constructing microfluidic platforms with sorting, merging, transporting, and mixing of drops without a programmable control of electrical signals. Also, this method has a potential in heat transfer applications because heat removal capacity can be enhanced significantly through drop oscillation

Size-Selective Sliding of Sessile Drops on a Slightly Inclined Plane Using Low-Frequency AC Electrowetting

When placed on an inclined solid plane, drops often stick to the solid surface due to pinning forces caused by contact angle hysteresis. When the drop size or the plane’s incline angle is small, the drop is difficult to slide due to a decrease in gravitational force. Here we demonstrate that small drops (0.4–9 μL) on a slightly inclined plane (∼12°, Teflon and parylene-C surface) can be mobilized through patterned electrodes by applying low-frequency ac electrowetting under 400 Hz (110–180 V_rms), which has a mechanism different from that of the high-frequency ac method that induces sliding by reducing contact angle hysteresis. We attribute the sliding motion of our method to a combination of contact angle hysteresis and interfacial oscillation driven by ac electrowetting instead of the minimization of contact angle hysteresis at a high frequency. We investigated the effects of ac frequency on the sliding motion and terminal sliding of drops; the terminal sliding velocity is greatest at resonance frequency. Varying the electrowetting number (0.21–0.56) at a fixed frequency (40 Hz) for 5 μL drops, we found an empirical relationship between the electrowetting number and the terminal sliding velocity. Using the relationship between the drop size and ac frequency, we can selectively slide drops of a specific size or merge two drops along an inclined plane. This simple method will help with constructing microfluidic platforms with sorting, merging, transporting, and mixing of drops without a programmable control of electrical signals. Also, this method has a potential in heat transfer applications because heat removal capacity can be enhanced significantly through drop oscillation

Clarithromycin Attenuates Radiation-Induced Lung Injury in Mice

<div><p>Radiation-induced lung injury (RILI) is a common and unavoidable complication of thoracic radiotherapy. The current study was conducted to evaluate the ability of clarithromycin (CLA) to prevent radiation-induced pneumonitis, oxidative stress, and lung fibrosis in an animal model. C57BL/6J mice were assigned to control, irradiation only, irradiation plus CLA, and CLA only groups. Test mice received single thoracic exposures to radiation and/or oral CLA (100 mg/kg/day). Histopathologic findings and markers of inflammation, fibrosis, and oxidative stress were compared by group. On a microscopic level, CLA inhibited macrophage influx, alveolar fibrosis, parenchymal collapse, consolidation, and epithelial cell changes. The concentration of collagen in lung tissue was lower in irradiation plus CLA mice. Radiation-induced expression of tumor necrosis factor (TNF)-α, TNF receptor 1, acetylated nuclear factor kappa B, cyclooxygenase 2, vascular cell adhesion molecule 1, and matrix metallopeptidase 9 were also attenuated by CLA. Expression levels of nuclear factor erythroid 2-related factor 2 and heme oxygenase 1, transforming growth factor-β1, connective tissue growth factor, and type I collagen in radiation-treated lungs were also attenuated by CLA. These findings indicate that CLA ameliorates the deleterious effects of thoracic irradiation in mice by reducing pulmonary inflammation, oxidative damage, and fibrosis.</p></div

Effects of clarithromycin on VCAM-1 and MMP-9 expression levels in irradiated lungs of mice.

<p>(A) VCAM-1 expression in lungs of control (CTL), radiation only (RT), radiation + clarithromycin (RT+CLA), and clarithromycin only (CLA) animal groups. (B) MMP-9 expression in lungs of respective groups. Densitometry values were normalized to β-actin and data are presented as mean ± SEM (n = 2–6 mice per group). *<i>p</i><0.05 vs CTL mice; †<i>p</i><0.05 vs RT mice.</p

Effects of clarithromycin on TGFβ-1, CTGF, and collagen type I gene expressions and on tissue collagen concentration.

<p>(A) TGFβ-1 expression in lungs of control (CTL), radiation only (RT), radiation + clarithromycin (RT+CLA), and clarithromycin only (CLA) animal groups. (B) CTGF and collagen type I gene expressions in lungs of respective groups. Densitometry values were normalized to β-actin and data are presented as mean ± SEM (n = 2–6 mice per group). (C) Collagen concentration in lung tissue by group (n = 2–9 mice per group, Sircol collagen assay). *<i>p</i><0.05 vs CTL mice; †<i>p</i><0.05 vs RT mice.</p

Effects of clarithromycin on radiation-induced macrophage influx, alveolar septal changes, and apoptosis in lungs of mice.

<p>(A) Representative photomicrographs of H&E-stained lung sections from control (CTL), radiation only (RT), radiation + clarithromycin (RT+CLA), and clarithromycin only (CLA) animal groups (macrophage at arrow). (B) Representative photomicrographs of sirius red-stained lung sections from each group. Thin arrow indicates macrophage and bold arrow indicates thickened, fibrotic alveolar septum). Scale bar = 100μm. (C) Cleaved caspase-3 expression in lungs of control (CTL), radiation only (RT), radiation + clarithromycin (RT+CLA), and clarithromycin only (CLA) animal groups. (D) Cleaved caspase-3 expression in lungs of respective groups. Densitometry values were normalized to β-actin and data are presented as mean ± SEM (n = 2–6 mice per group). *<i>p</i><0.05 vs CTL mice; †<i>p</i><0.05 vs RT mice.</p

Effects of clarithromycin on Nrf2 and HO-1 expression levels and on HO-1 immunoreactivity in irradiated lungs of mice.

<p>(A) Nrf2 and HO-1 expression levels in lungs of control (CTL), radiation only (RT), radiation + clarithromycin (RT+CLA), and clarithromycin only (CLA) animal groups. Densitometry values were normalized to β-actin and data are presented as mean ± SEM (n = 2–6 mice per group). *p<0.05 vs CTL mice; †p<0.05 vs RT mice. (B) Immunostained HO-1 in lung tissue by group. Scale bar = 100 μm.</p

Effects of clarithromycin on inflammation in irradiated lungs of mice.

<p>(A) TNF-α expression in lungs of control (CTL), radiation only (RT), radiation + clarithromycin (RT + CLA), and clarithromycin only (CLA) animal groups. (B) TNFR1 and TNFR2 expression in lungs of respective groups. (C and D) Acetylated NF-κB p65 and (E) COX-2 expression in lungs of respective groups. Densitometry values were normalized to β-actin and data are presented as mean ± SEM (n = 2–6 mice per group). *<i>p</i><0.05 vs CTL mice; †<i>p</i><0.05 vs RT mice. (F) Immunostained COX-2 in lung tissue by group. Scale bar = 100 μm.</p

Additional file 1 of Endobronchial valves for emphysema and persistent air-leak: 10-year experience in an Asian country

Additional file 1. Institutional review board protocol numbers. Documentation of the IRB protocol numbers