A mass‐conservative staggered immersed boundary model for solving the shallow water equations on complex geometries

In this work, an approach is proposed for solving the 3D shallow water equations with embedded boundaries that are not aligned with the underlying horizontal Cartesian grid. A hybrid cut‐cell/ghost‐cell method is used together with a direction‐splitting implicit solver: Ghost cells are used for the momentum equations in order to prescribe the correct boundary condition at the immersed boundary, while cut cells are used in the continuity equation in order to conserve mass. The resulting scheme is robust, does not suffer any time step limitation for small cut cells, and conserves fluid mass up to machine precision. Moreover, the solver displays a second‐order spatial accuracy, both globally and locally. Comparisons with analytical solutions and reference numerical solutions on curvilinear grids confirm the quality of the method. Copyright © 2015 John Wiley & Sons, Ltd.     

Exact pressure integrations on submerged bodies in waves using a quadtree adaptive mesh algorithm

The development of an adaptive free surface, mesh cutting, methodology, in order to analytically integrate pressures on varying wet parts of partially submerged surfaces in the presence of waves, is presented. Given a function of free‐surface elevation, the algorithm checks for the intersection of the body with the free surface and, based on user‐defined parameters, modifies the initial mesh, by subdividing the elements where necessary and eliminating others, via a quadtree approach. Redundant sub‐divisions, generated in the quad‐division process, are partially eliminated, but the quadrilateral nature of the elements is always kept. The free‐surface function must be single‐valued and its definition domain simply connected. Hydrostatic and Froude–Krylov forces are computed exactly on each panel by means of analytical formulations, which are derived and presented, based on the theory of linear gravity waves and from applying Green's theorem. Copyright © 2014 John Wiley & Sons, Ltd.     

功率对氘代辉光放电聚合物结构和力学性能的影响

采用射频辉光放电聚合技术,在低压等离子体聚合装置上开展在5~20 W功率下氘代辉光放电聚合物薄膜的制备及性能研究。利用傅里叶变换红外吸收光谱仪表征薄膜的化学结构,讨论了功率变化对其官能团结构的影响规律。利用元素分析仪和纳米压痕仪表征薄膜中氘原子的相对含量和薄膜的力学性能。研究表明:随着功率的升高,薄膜中的氘含量先升高后降低,在10W时达到最大,薄膜中SP3 CD的相对含量增加,SP3 CD2的相对含量减小;聚合物薄膜的硬度和杨氏模量均随功率的增加而减小。     

A Multifunctional Surface That Simultaneously Balances Hydrophilic Enzyme Catalysis and Hydrophobic Water Repellency

The compatibility of multiple functions at a single interface is difficult to achieve, but is even more challenging when the functions directly counteract one another. This study provides insight into the creation of a simultaneously multifunctional surface formed by balancing two orthogonal functions; water repellency and enzyme catalysis. A partially fluorinated thiol is used to impart bulk hydrophobicity on the surface, and an N‐hydroxysuccinimide ester‐terminated thiol provides a specific anchoring sites for the covalent enzyme attachment. Different ratios of the two thiols are mixed together to form amphiphilic self‐assembled monolayers, which are characterized with polarization‐modulation infrared reflection–absorption spectroscopy and contact angle goniometry. The enzyme activity is measured by a fluorescence assay. With the results collected here, specific surface compositions are identified at which the orthogonal functions of water repellency and enzyme catalysis are balanced and exist simultaneously. An understanding of how to effectively balance orthogonal functions at surfaces can be extended to a number of higher‐scale applications.     

Modulation of Self-healing of Polyion Complex Hydrogel by Ion-specific Effects

We have prepared polyion complex (PIC) hydrogel consisting of poly(3-(methacryloylami no) propyl-trimethylamonium chloride) and poly(sodium p-styrenesulfonate) polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the selfhealing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.     

Sensitive detection of drug vapors using an ion funnel interface for secondary electrospray ionization mass spectrometry

In this study, we use an ion funnel (IF) at ambient pressure to enhance the sensitivity of secondary electrospray ionization (SESI). Atenolol, salbutamol and cocaine as test compounds are delivered to the SESI interface in the gas phase and are charged with three nano electrosprays. In our experiments, we show that the compounds can be detected at concentrations in the low pptv range, which is an increase of two orders of magnitude compared with the results without the IF. With a standard SESI interface, the compounds could not be detected at all. With the use of the SESI IF interface for the headspace analysis of bananas and limes, we can detect many more compounds and at higher intensities than with a standard SESI interface. Copyright © 2012 John Wiley & Sons, Ltd.     

Sequential-dissociation kinetics of non-covalent complexes of DNA with multiple proteins in separation-based approach: General theory and its application

Binding of multiple proteins to DNA is crucial in many regulatory cellular processes. The kinetics of assembly and disassembly of DNA–multiple protein complexes is very difficult to study in detail due to the lack of suitable experimental approaches. A separation-based approach has been recently proposed to resolve disassembly kinetics of such complexes. While conceptually simple, the separation-based approach generates experimental data with very complex patterns. The analysis of these patterns is a challenging problem on its own. Here we report on a mathematical approach that can extract a solution for the experimental data obtained in separation-based analysis of sequential dissociation of a DNA complex with multiple proteins. This case describes the dissociation of proteins one-by-one from the complex. Generally speaking, a mathematical solution of such problems requires calculations of multiple integrals. Our approach reduces this procedure to taking double integrals and constructing their superposition. We tested this approach with the experimental data obtained for three-step sequential dissociation of complexes of DNA with two protein copies.     

Critical Trace Trudinger-Moser Inequalities on a Compact Riemann Surface with Smooth Boundary

In this paper, the author concerns two trace Trudinger-Moser inequalities and obtains the corresponding extremal functions on a compact Riemann surface (Σ, g) with smooth boundary ?Σ. Explicitly, let λ₁(?Σ) = inf u∈W^1,2 (Σ,g),R ?Σ udsg=0,u6≡0 R Σ(|?gu|2 + u2 )dvg R ?Σ u2 dsg and H = n u ∈ W^1,2 (Σ, g) : Z Σ(|?gu|2 + u2 )dvg ? α Z ?Σ u2dsg ≤ 1 and Z ?Σ u dsg = 0o ,where W^1,2 (Σ, g) denotes the usual Sobolev space and ?g stands for the gradient operator.By the method of blow-up analysis, we obtain sup u∈H Z ?Σ e πu2 dsg ( < +∞, 0 ≤ α < λ1(?Σ),= +∞, α ≥ λ1(?Σ).Moreover, the author proves the above supremum is attained by a function uα ∈ H∩C∞(Σ)for any 0 ≤ α < λ1(?Σ). Further, he extends the result to the case of higher order eigenvalues. The results generalize those of [Li, Y. and Liu, P., Moser-Trudinger inequality on the boundary of compact Riemannian surface, Math. Z., 250, 2005, 363–386], [Yang,Y., Moser-Trudinger trace inequalities on a compact Riemannian surface with boundary,Pacific J. Math., 227, 2006, 177–200] and [Yang, Y., Extremal functions for TrudingerMoser inequalities of Adimurthi-Druet type in dimension two, J. Diff. Eq., 258, 2015,3161–3193]     

Study and optimization of the ultrasound-enhanced cleaning of an ultrafiltration ceramic membrane through a combined experimental–statistical approach

Membrane fouling is one of the main drawbacks of ultrafiltration technology during the treatment of dye-containing effluents. Therefore, the optimization of the membrane cleaning procedure is essential to improve the overall efficiency. In this work, a study of the factors affecting the ultrasound-assisted cleaning of an ultrafiltration ceramic membrane fouled by dye particles was carried out. The effect of transmembrane pressure (0.5, 1.5, 2.5 bar), cross-flow velocity (1, 2, 3 m s⁻¹), ultrasound power level (40%, 70%, 100%) and ultrasound frequency mode (37, 80 kHz and mixed wave) on the cleaning efficiency was evaluated. The lowest frequency showed better results, although the best cleaning performance was obtained using the mixed wave mode.A Box–Behnken Design was used to find the optimal conditions for the cleaning procedure through a response surface study. The optimal operating conditions leading to the maximum cleaning efficiency predicted (32.19%) were found to be 1.1 bar, 3 m s⁻¹ and 100% of power level.Finally, the optimized response was compared to the efficiency of a chemical cleaning with NaOH solution, with and without the use of ultrasound. By using NaOH, cleaning efficiency nearly triples, and it improves up to 25% by adding ultrasound.