Anisotropic imperfect interface in elastic particulate composite with initial stress

The model of an anisotropic interface in an elastic particulate composite with initial stress is developed as the first-order approximation of a transversely isotropic interphase between an isotropic matrix and spherical particles. The model involves eight independent parameters with a clear physical meaning and conventional dimensionality. This ensures its applicability at various length scales and flexibility in modeling the interfaces, characterized by the initial stress and discontinuity of the displacement and stress fields. The relevance of this model to the theory of material interfaces and its applicability in nanomechanics is discussed. The proposed imperfect interface model is incorporated in the unit cell model of a spherical particle composite with thermal stress owing to uniform temperature change. The rigorous solution to the model boundary value problem is obtained using the multipole expansion method. The reported accurate numerical data confirm the correctness of the developed theory, provide an estimate of its accuracy and applicability limits in the multiparticle environment, and reveal significant effects of the interphase or interface anisotropy and initial stress on the local fields and overall thermoelastic properties of the composite.

Terahertz Sensing for R/S Chiral Ibuprofen via All-Dielectric Metasurface with Higher-Order Resonance

A terahertz (THz) all-dielectric metasurface with crescent cylinder arrays for chiral drug sensing has been demonstrated. Through the multipole expansion method, we theoretically found that breaking the symmetry of the metasurface can excite higher-order resonance modes and provide stronger anisotropy as well as enhanced sensitivity for the surroundings, which gives a better sensing performance than lower-order resonance. Based on the frequency shift and transmittance at higher-order resonance, we carried out the sensing experiments on (R)-(−)-ibuprofen and (S)-(+)-ibuprofen solution on the surface of this metasurface sensor. We were able to monitor the concentrations of ibuprofen solutions, and the maximum sensitivity reached 60.42 GHz/mg. Furthermore, we successfully distinguished different chiral molecules such as (R)-(−)-ibuprofen and (S)-(+)-ibuprofen in the 5 μL trace amount of samples. The maximum differentiation was 18.75 GHz/mg. Our analysis confirms the applicability of this crescent all-dielectric metasurface to enhanced sensing and detection of chiral molecules, which provides new paths for the identification of biomolecules in a trace amount.

Orientation order parameters and effective conductivity of a 2-D solid with partially disordered array of circular inhomogeneities

The paper focuses on the quantitative characterization of the microstructure of a two-dimensional heterogeneous solid with circular inhomogeneities that may vary from perfectly periodic arrangement to completely random one. This characterization is linked to the calculation of the effective conductivity of the material. The partially disordered system of disks is generated in the framework of the representative unit cell model using Metropolis algorithm. The orientation order metrics are taken as the structural parameters providing a quantitative measure of disorder, and their variation caused by the gradual disordering of the periodic system is assessed. The effective conductivity of the heterogeneous solid with partially disordered microstructure is evaluated by the multipole expansion method. It is shown that effective conductivity cannot be fully characterized by only one orientation order metric, and the required additional ones are identified.

Analysis of water wave interaction with a submerged quarter-circular breakwater using multipole method

This article studies water wave interaction with a submerged quarter-circular breakwater based on potential theory and multipole expansion method. The obliquely and normally incident waves are independently considered. The series solution of velocity potential in the external fluid domain is expressed through the multipole expansions, while the series solution of velocity potential in the quarter-circular internal fluid domain is obtained through the separation of variables. Then, the unknown coefficients in the series solutions are determined by matching the boundary conditions between external and internal fluid domains. The calculation methods for the reflection and transmission coefficients of the submerged quarter-circular breakwater as well as the horizontal and vertical wave forces on the breakwater are presented. The wave forces acting on the submerged breakwater with a seaside quarter-circular-arc and that with a leeside quarter-circular-arc are compared. The hydrodynamic quantities of the submerged quarter-circular breakwater are also compared with those of the submerged semi-circular breakwater. In addition, the effects of breakwater radius, incident frequency, and incident angle on the hydrodynamic quantities of the quarter-circular breakwater are clarified. Valuable results for practical engineering application are drawn.

Forbidden transitions in nuclear weak processes relevant to neutrino detection, nucleosynthesis and evolution of stars

The distribution of the spin-dipole strengths in 16O and neutrino-induced reactions on 16O areinvestigated by shell-model calculations with new shell-model Hamiltonians. Chargedcurrent and neutral-current reactioncross sections are valuated in various particle and γ emission channels as well as the total ones at neutrinoenergies up to Eν≈ 100 MeV. Effects of multiparticle emission channels, especially the αp emission channels, on nucleosynthesis of 11B and 11C in core-collapse supernova explosions are investigated. The MSW neutrino oscillation effects oncharged-current reaction cross sections are investigated for future supernova burst. Electron capture rates for a forbidden transition 20Ne(Og.s.+) → 20F(2g.s.+) in stellar environments are evaluated by the multipole expansion method with the use of shell model Hamiltonians, and compared with those obtained by a prescription that treats the transition as an allowed GamowTeller (GT) transition. Different electron energy dependence of the transition strengths between the two methods is found to lead to sizable differences in the weak rates of the two methods.