New Approach on the General Shape Equation of Axisymmetric Vesicles

The general Helfrich shape equation determined by minimizing the curvature free energy describes the equilibrium shapes of the axisymmetric lipid bilayer vesicles in different conditions. It is a non-linear differential equation with variable coefficients. In this letter, by analyzing the unique property of the solution, we change this shape equation into a system of the two differential equations. One of them is a linear differential equation. This equation system contains all of the known rigorous solutions of the general shape equation. And the more general constraint conditions are found for the solution of the general shape equation.Comment: 8 pages, LaTex, submit to Mod. Phys. Lett.

Vibrations of a plate on a two-parameter foundation subjected to moving rectangular loads of varying velocities

The vibrational characteristics of a plate on a two-parameter foundation under moving rectangular loads with variable velocities are investigated, and the general solution for the dynamic deflection of the plate is derived using the double Fourier transform. Employing the fast Fourier Transform, a rigid pavement is chosen to obtain numerical results, which are consistent with those from the classical solution. The effects of initial load velocity, load acceleration, load deceleration and horizontal resistance at the plate bottom on the dynamic deflection are discussed. An expression to predict the critical velocity is derived, and the results from this formula show very good agreement with those from the numerical analysis. The numerical analysis indicates that the maximum dynamic deflection occurs when the load velocity reaches the critical velocity for the plate. The initial velocity, the acceleration and the deceleration of the rectangular load influence the dynamic response, and the dynamic deflection of the plate at the critical velocity decreases significantly as they increases

Tide-surge interaction in the Pearl River Estuary: A case study of Typhoon Hato

In this study, the characteristics and mechanisms of tide-surge interaction in the Pearl River Estuary (PRE) during Typhoon Hato in August 2017 are studied in detail using a 3D nearshore hydrodynamic model. The wind field of Typhoon Hato is firstly reconstructed by merging the Holland parametric tropical cyclone model results with the CFSR reanalysis data, which enables the model to reproduce the pure astronomical tides and storm tides well; in particular, the distinctive oscillation pattern in the measured water levels due to the passage of the typhoon has been captured. Three different types of model runs are conducted in order to separate the water level variations due to the astronomical tide, storm surge, and tide-surge interactions in the Pearl River Estuary. The results show the strong tidal modulation of the surge level, as well as alteration of the phase of surge, which also changes the peak storm tidal level, in addition to the tidal modulation effects. In order to numerically assess the contributions of three non-linear processes in the tide-surge interaction and quantify their relative significance, the widely used “subtraction” approach and a new “addition” approach are tested in this study. The widely used “subtraction” approach is found to be unsuitable for the assessment due to the “rebalance” effect, and thus the new “addition” approach is proposed along with a new indicator to represent the tide-surge interaction, from which more reasonable results are obtained. Detailed analysis using the “addition” approach indicates that the quadratic bottom friction, shallow water effect, and nonlinear advective effect play the first, second, and third most important roles in the tidal-surge interaction in the estuary, respectively

H2O+: An Improved Framework for Hybrid Offline-and-Online RL with Dynamics Gaps

Solving real-world complex tasks using reinforcement learning (RL) without high-fidelity simulation environments or large amounts of offline data can be quite challenging. Online RL agents trained in imperfect simulation environments can suffer from severe sim-to-real issues. Offline RL approaches although bypass the need for simulators, often pose demanding requirements on the size and quality of the offline datasets. The recently emerged hybrid offline-and-online RL provides an attractive framework that enables joint use of limited offline data and imperfect simulator for transferable policy learning. In this paper, we develop a new algorithm, called H2O+, which offers great flexibility to bridge various choices of offline and online learning methods, while also accounting for dynamics gaps between the real and simulation environment. Through extensive simulation and real-world robotics experiments, we demonstrate superior performance and flexibility over advanced cross-domain online and offline RL algorithms

Mangrove forests can be an effective coastal defence in the Pearl River Delta, China

Coastal vegetation can reduce extreme water levels during storm events, but the controlling factors and processes in complex estuary or delta systems are still unclear. This limits an effective implementation of nature-based coastal defences in delta mega-cities in low-lying coastal areas. Here we have numerically modelled how mangroves can offer coastal protection to the large coastal cities located in the Pearl River Delta (China), such as Guangzhou and Shenzhen, during strong typhoons, like Hato (2017). Water level attenuation by mangroves is effective during extreme water level conditions and differences in mangrove forests’ properties drive their coastal protection function. The local (within-wetland) attenuation of extreme water levels is more effective with wide vegetation patches and higher vegetation drag. Narrower vegetation patches can still provide non-local (upstream) water level attenuation if located in the upper estuary channels, but their design needs to avoid amplification of water levels in other delta areas

Determination of pantoprazole in rat plasma by LC–MS/MS and its application to pharmacokinetics

A highly sensitive liquid chromatographic mass spectrometric (LC-MS/MS) method for determination of pantoprazole in rat plasma using omeprazole as the internal standard (IS) was developed. Plasma samples were precipitated by acetonitrile and separated on a Zorbax SB-C18 column with gradient profile at a flow of 0.4 mL/min. Detection was carried out by SIM mode on an ion-trap LC-MS/MS system with an electrospray ionization interface. The lower limit of quantification (LLOQ) was 5 ng/mL. Calibration curve was linear over the range from 5 to 5000 ng/mL. The intra- and inter-run relative standard deviations of the assay were less than 7 %. The mean absolute recoveries determined at the concentrations of 25, 400, and 4000 ng/mL were 87.40 ± 4.40 %, 87.77 ± 3.30 %, and 92.78 ± 5.02 %, respectively. The method was applied to the pharmacokinetic of 15 mg/kg of pantoprazole in six rats.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Microbiology, ecology, and application of the nitrite-dependent anaerobic methane oxidation process

Nitrite-dependent anaerobic methane oxidation (n-damo), which couples the anaerobic oxidation of methane to denitrification, is a recently discovered process mediated by “Candidatus Methylomirabilis oxyfera.” M. oxyfera is affiliated with the “NC10” phylum, a phylum having no members in pure culture. Based on the isotopic labeling experiments, it is hypothesized that M. oxyfera has an unusual intra-aerobic pathway for the production of oxygen via the dismutation of nitric oxide into dinitrogen gas and oxygen. In addition, the bacterial species has a unique ultrastructure that is distinct from that of other previously described microorganisms. M. oxyfera-like sequences have been recovered from different natural habitats, suggesting that the n-damo process potentially contributes to global carbon and nitrogen cycles. The n-damo process is a process that can reduce the greenhouse effect, as methane is more effective in heat-trapping than carbon dioxide. The n-damo process, which uses methane instead of organic matter to drive denitrification, is also an economical nitrogen removal process because methane is a relatively inexpensive electron donor. This mini-review summarizes the peculiar microbiology of M. oxyfera and discusses the potential ecological importance and engineering application of the n-damo process

A high-performance UV photodetector with superior responsivity enabled by a synergistic photo/thermal enhancement of localized surface plasmon resonance

In this paper, we propose a new strategy to enhance the photoelectric performance of ultraviolet (UV) photodetectors by exploiting a synergistic photo-thermal effect which is induced by a localized surface plasmon resonance. We demonstrate that a W18O49 plasmonic semiconductor is able to improve the performance of target photodetectors as a result of a localized surface plasmon resonance, which increases light absorption, enhances the photothermal effect to deliver an increased photocurrent, and provides photo-induced “hot electrons” to limit carrier depletion over prolonged light illumination. Consequently, a UV photodetector based on W18O49/TiO2 nanofibers is shown to exhibit an excellent photodetection performance with a high responsivity of up to 1.6 × 104 A W−1, which is five times greater than that of the pure TiO2 analogue and greatly exceeds those of the TiO2-based photodetectors reported to date.</p

A high-performance UV photodetector with superior responsivity enabled by a synergistic photo/thermal enhancement of localized surface plasmon resonance

In this paper, we propose a new strategy to enhance the photoelectric performance of ultraviolet (UV) photodetectors by exploiting a synergistic photo-thermal effect which is induced by a localized surface plasmon resonance. We demonstrate that a W18O49 plasmonic semiconductor is able to improve the performance of target photodetectors as a result of a localized surface plasmon resonance, which increases light absorption, enhances the photothermal effect to deliver an increased photocurrent, and provides photo-induced “hot electrons” to limit carrier depletion over prolonged light illumination. Consequently, a UV photodetector based on W18O49/TiO2 nanofibers is shown to exhibit an excellent photodetection performance with a high responsivity of up to 1.6 × 104 A W−1, which is five times greater than that of the pure TiO2 analogue and greatly exceeds those of the TiO2-based photodetectors reported to date.</p