We describe the fabrication of a biomimically designed superhydrophobic poly(ε‐caprolactone) surface, which was obtained using a modified electrostatic process. The fabricated surface exhibits a micron‐sized pyramid structure consisting of accumulated droplets and nanofibres. By using this simple one‐step process, we can achieve a superhydrophobic surface having both a high water contact angle and low threshold sliding angle, similar to that of the superhydrophobic plant leaf.
The underwater hearing sensitivity of a young male harbor porpoise for tonal signals of various signal durations was quantified by using a behavioral psychophysical technique. The animal was trained to respond only when it detected an acoustic signal. Fifty percent detection thresholds were obtained for tonal signals (15 frequencies between 0.25-160 kHz, durations 0.5-5000 ms depending on the frequency; 134 frequency-duration combinations in total). Detection thresholds were quantified by varying signal amplitude by the 1-up 1-down staircase method. The hearing thresholds increased when the signal duration fell below the time constant of integration. The time constants, derived from an exponential model of integration [Plomp and Bouman, J. Acoust. Soc. Am. 31, 749-758 (1959)], varied from 629 ms at 2 kHz to 39 ms at 64 kHz. The integration times of the porpoises were similar to those of other mammals including humans, even though the porpoise is a marine mammal and a hearing specialist. The results enable more accurate estimations of the distances at which porpoises can detect short-duration environmental tonal signals. The audiogram thresholds presented by Kastelein et al. [J. Acoust. Soc. Am. 112, 334-344 (2002)], after correction for the frequency bandwidth of the FM signals, are similar to the results of the present study for signals of 1500 ms duration. Harbor porpoise hearing is more sensitive between 2 and 10 kHz, and less sensitive above 10 kHz, than formerly believed. 相似文献
We visually observed that a dropwise condensation occurred initially and later changed into a filmwise condensation on hydrophobic textured surface at atmosphere pressure condition. It was observed that the condensate nucleated on the pillar side walls of the micro structure and the bottom wall adhered to the walls and would not be lifted to form a spherical water droplet using environmental scanning electron microscope. 相似文献
This paper proposes a robust adaptive backstepping synchronization method for a class of uncertain chaotic systems. Unknown factors including system uncertainties and external disturbances are estimated by a fuzzy disturbance observer. By use of the fuzzy disturbance observer, any prior information about the unknown factors is not need. The proposed method using the estimated values guarantees the global synchronization for chaotic systems with mismatched uncertainties in the sense of uniform ultimate boundedness. Finally, numerical examples are presented to show the effectiveness of the method. 相似文献
This paper contains a discussion of a relativistic spin-0 system in the presence of a Gödel-type background space-time. The Duffin–Kemmer–Petiau (DKP) equation in the presence of a Gödel-type background space-time is studied in detail. After a derivation of the final form of this equation in the considered framework, free spin-0 particles have been studied. 相似文献
We report the synthesis of Li2CoSiO4 by the sol-gel method and the preparation of a composite electrode by incorporating functionalized multi-walled carbon nanotubes (fn. MWCNTs) as conductive additive. XRD pattern of the composite confirms the structural stability of Li2CoSiO4 even after the addition of fn. MWCNTs. SEM images of the composite reveal the presence of conductive bridges formed by MWCNTs between the submicron-sized particles of Li2CoSiO4. The cyclic voltammograms of the composite cathode show redox peaks with higher current density than pure Li2CoSiO4 and the current density increases with increase in sweep rate. The diffusion coefficient of lithium has been improved by the addition of fn. MWCNTs from 1 × 10?14 to 8 × 10?14 cm2/s as calculated using Randles-Sevcik equation. The charge-discharge cycling performance of both pure Li2CoSiO4 and composite cathode has been discussed. 相似文献
Here, we present the spectroscopic ellipsometry investigation of synthetically grown wafer-scale two-dimensional (2D) MoS2 and WSe2 films to access quality and thickness uniformity. MoS2 and WSe2 samples were grown by chemical vapor deposition and atomic layer deposition, respectively. Complex dielectric function () and thickness information of these 2D films were extracted from the measured data using multilayer optical calculations. Broad spectral range (1.2–6 eV) and multiple angles of incidence were used to reduce correlations among fitting parameter. Lineshape of ε of MoS2 and WSe2 monolayer films are consistent with literature but shows higher values, suggests better quality of our samples. Eight-inch wafer size MoS2 monolayer sample shows ~ 70% uniformity with an average thickness of 0.65 ± 0.2 nm, and three-layer WSe2 sample of 8 × 1 cm2 area shows ~ 80% uniformity with an average thickness of 2.5 ± 0.4 nm. Our results will be helpful to accelerate commercialization process of 2D devices. 相似文献
Anaplastic thyroid cancer (ATC) is one of the most fatal human malignancies. Ursi Fel (UF) is the bile of a brown bear that has been traditionally used for heat clearance and toxin relief in Korean and Chinese medicines. In this study, we determined the anticancer effects of a UF extract and its active compound, ursodeoxycholic acid (UDCA), in FRO human ATC cells. FRO cells were treated with UF extract and UDCA at different concentrations for various durations. Cell viability was measured using an MTT assay. Cell apoptosis was investigated by flow cytometric analysis following Annexin V and propidium iodide (PI) staining, and Hoechst staining was used to observe nuclear fragmentation. The expression of pro-apoptotic (Bax, caspase-3, cytochrome c, and PARP), anti-apoptotic (Bcl-2), and angiogenetic (TGF-β, VEGF, N-cadherin, and sirtuin-1) proteins and the phosphorylation of Akt and mechanistic target of rapamycin (mTOR) were determined by western blot analysis. Treatment with UF extract at 10, 25, and 50 μg/mL and UDCA at 25, 50, and 100 μM/mL significantly inhibited the growth of FRO cells in a dose-dependent manner. Flow cytometry and Hoechst staining revealed an increase in the apoptosis of FRO cells mediated by UF extract and UDCA in a dose-dependent manner. UF extract (25 and 50 μg) and UDCA (50 and 100 μM) significantly increased the expression of Bax, caspase-3, cytochrome c, and PARP and inhibited the expression of Bcl-2, TGF-β, VEGF, N-cadherin, and sirtuin-1 in FRO cells. Furthermore, UF extract and UDCA treatment stimulated Akt phosphorylation and inhibited mTOR phosphorylation in these cells. These results indicate that UF extract and UDCA exert anticancer properties in FRO cells by inducing apoptosis and inhibiting angiogenesis via regulating the Akt/mTOR signaling pathway. 相似文献
By employing a new template method using surfactant/silicate solution template, highly mesoporous carbon/manganese oxide composite materials were prepared in one step and their performance as electrodes of supercapacitor was investigated. Because of the high dispersion of Mn oxide and well developed mesoporosity of carbon, a high specific capacitance and an improved rate performance were observed at the electrodes fabricated by Mn/carbon composite materials. 相似文献