Notes

Alpha dog helical surfactant-like proteins self-assemble in to pH-dependent nanostructures.
We study the problem of resonant extraordinary transmission of electromagnetic and acoustic waves through subwavelength slits in an infinite plate, whose thickness is close to a half-multiple of the wavelength. We build on the matched-asymptotics analysis of Holley & Schnitzer (2019 Wave Motion91, 102381 (doi10.1016/j.wavemoti.2019.102381)), who considered a single-slit system assuming an idealized formulation where dissipation is neglected and the electromagnetic and acoustic problems are analogous. We here extend that theory to include thin dissipative boundary layers associated with finite conductivity of the plate in the electromagnetic problem and viscous and thermal effects in the acoustic problem, considering both single-slit and slit-array configurations. By considering a distinguished boundary-layer scaling where dissipative and diffractive effects are comparable, we develop accurate analytical approximations that are generally valid near resonance; the electromagnetic-acoustic analogy is preserved up to a single parameter that is provided explicitly for both scenarios. The theory is shown to be in excellent agreement with GHz-microwave and kHz-acoustic experiments in the literature.Transient electrokinetic (EK) flows involve the transport of conductivity gradients developed as a result of mixing of ionic species in the fluid, which in turn is affected by the electric field applied across the channel. The presence of three different coupled equations with corresponding different time scales makes it difficult to model the problem using the lattice Boltzmann method (LBM). The present work aims to develop a hybrid LBM and finite difference method (FDM)-based model which can be used to study the electro-osmotic flows (EOFs) and the onset of EK instabilities using an Ohmic model, where fluid and conductivity transport are solved using LBM and the electric field is solved using FDM. The model developed will be used to simulate three different problems (i) EOF with varying zeta-potential on the wall, (ii) similitude in EOF, and (iii) EK instabilities due to the presence of conductivity gradients. Problems (i) and (ii) will be compared with the analytical results and problem (iii) will be compared with the simulations of a spectral method-based numerical model. The results obtained from the present simulations will show that the developed model is capable of studying transient EK flows and of predicting the onset of instability.The mean-field homogenization scheme proposed by Lahellec & Suquet (2007 Int. J. Solids Struct.44, 507-529 (doi10.1016/j.ijsolstr.2006.04.038)) and revisited in a companion paper (Idiart et al. 2020 Proc. R. Soc. A 20200407 (doi10.1098/rspa.2020.0407)) is applied to random mixtures of a viscoelastic solid phase and a rigid phase. Two classes of mixtures with different microstructural arrangements are considered. In the first class the rigid phase is dispersed within the continuous viscoelastic phase in such a way that the elastic moduli of the mixture are given exactly by the Hashin-Shtrikman formalism. GSK-3 inhibitor In the second class, both phases are intertwined in such a way that the elastic moduli of the mixture are given exactly by the Self-Consistent formalism. Results are reported for specimens subject to various complex deformation programmes. The scheme is found to improve on earlier approximations of common use and even recover exact results under several circumstances. However, it can also generate highly inaccurate predictions as a result of the loss of convexity of the free-energy density. An auspicious procedure to partially circumvent this issue is advanced.A homogenization scheme for viscoelastic composites proposed by Lahellec & Suquet (2007 Int. J. Solids Struct.44, 507-529 (doi10.1016/j.ijsolstr.2006.04.038)) is revisited. The scheme relies upon an incremental variational formulation providing the inelastic strain field at a given time step in terms of the inelastic strain field from the previous time step, along with a judicious use of Legendre transforms to approximate the relevant functional by an alternative functional depending on the inelastic strain fields only through their first and second moments over each constituent phase. As a result, the approximation generates a reduced description of the microscopic state of the composite in terms of a finite set of internal variables that incorporates information on the intraphase fluctuations of the inelastic strain and that can be evaluated by mean-field homogenization techniques. In this work we provide an alternative derivation of the scheme, relying on the Cauchy-Schwarz inequality rather than the Legendre transform, and in so doing we expose the mathematical structure of the resulting approximation and generalize the exposition to fully anisotropic material systems.Interregional geological maps hold important information for geodynamic models. Here, we use such maps to visualize major conformable and unconformable contacts at interregional scales and at the level of geologic series from the Upper Jurassic onward across North and South America, Europe, Africa and Australia. We extract hiatus information from these paleogeological maps, which we plot in a paleogeographical reference frame to link the maps to the plate and plume modes of mantle convection. We assume that interregional patterns of hiatus surfaces are proxy records of continent-scale mantle-induced vertical motion of the lithosphere. We find significant differences in the distribution of hiatus across and between continents at the timescale of geologic series, that is ten to a few tens of millions of years (Myrs). This is smaller than the mantle transit time, which, as the timescale of convection, is about 100-200 Myrs. Our results imply that different timescales for convection and topography in convective support must be an integral component of time-dependent geodynamic Earth models, consistent with the presence of a weaker upper mantle relative to the lower mantle. Additional geological constraints together with interregional geological maps at the resolution of stages (1-2 Myrs), are needed to assist in future geodynamic interpretations of interregional geologic hiatus.
My Website: https://www.selleckchem.com/GSK-3.html