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A hybrid planar micro-lattice made of functionally graded materials is proposed where the active and passive constituents are constructed by functionally graded beams with and without partially distributed piezoelectric attachments respectively. The analytical model for predicting complex band structure is presented via the spectral element method in combination with the modified couple stress theory and power law, whose accuracy is validated by the finite element method. By adjusting size dependence, feedback control gain, material gradient and arrangement of piezo-patches, controllable wave propagation and attenuation is achieved, which further advances the implementation of optimizations to obtain ultra-wide low frequency stop bands. [ABSTRACT FROM AUTHOR]

This study investigates the size effects on the dispersion relation of the transverse waves propagating through micro-beam metamaterial covered by piezoelectric patches that are connected with external shunted circuits. Based on the modified couple stress theory and Hamilton's principle, the transfer matrix model is established for determining the complex band structure which incorporates the length scaling effect and the electromechanical resonance. Numerical results show the size-dependent behavior of the complex band structure in terms of the location, the range, and the decaying level. The differences are indicated between the results obtained by the non-classical model and the classical elasticity-based model and the effects of Poisson's ratio. The connection modes of the piezoelectric layers on the characteristics of transverse wave propagation and attenuation are also examined. Further, the tunable nature is demonstrated via investigating the influences of the unit cell length, the circuit parameters, and the distribution of piezoelectric materials on the attenuation diagram. [ABSTRACT FROM AUTHOR]

Current research on the inverse design of phononic crystals, which aim to retrieve optimal structures according to given band gaps, is limited to controlling elastic waves at the macro-scale. This work extends the concept to nano-scale and implements this concept with phononic nanobeam made up of functionally graded materials by applying the nonlocal strain gradient theory and the probabilistic tandem network (PTN), which is responsible for detecting size effects and unveiling implicit relationships between band gaps and nanostructures. An analytical model that has not been published before is proposed based on the plane wave expansion method to predict band structures within size, thickness and porosity effects, enabling quick preparation for composing a dataset to train the network. Acting as an auto-encoder-like framework, the component of PTN in the reverse path allows to effectively encode required band gaps into a latent space, while the network in the forward path serves as a surrogate model to map the candidates from the latent space to band gaps. Numerical results not only show the influences of size effects on band gaps but also verify the accuracy, diversity, and generalization ability to meet different requirements of the inverse design. The proposed PTN can fulfill the on-demand design by generating multiple phononic nanobeams possessing same man-made band gaps. Undoubtedly, the framework proposed in the present work makes it a promising approach to provide flexible and diversified solutions, paving the way to discovering innovative phononic crystals at nano-scale. • A nonclassic model is developed to predict band gaps with size and thickness effects. • The inverse design is realized for FGM PnCs at the nanoscale by DL-based framework. • Diversified feasible designs regarding same requirement of band gaps are obtained. • Accurate FGM nano-PnCs are produced corresponding to band gaps tailored on-demand. [ABSTRACT FROM AUTHOR]

Multilayer/bilayer tablets have been applied for the formulation of incompatible components for compound preparations, but more often they are used to modify drug release. The objective of this study was to explore the feasibility of developing, using a bilayer tablet strategy, an immediate- and extended-release formulation of amoxicillin. The formulation of each layer was optimized separately and the bilayer tablets were compressed at an immediate/extended layer weight ratio of 3:7. The in vitro release of the bilayer tablets was evaluated and it was found to be very similar to Moxatag®, an immediate- and extended-release formulation approved by FDA. The kinetic mechanism study showed that the release of the bilayer tablets correlated better with the Ritger–Peppas model (correlation coefficient R = 0.9963) and a non-Fickian drug release mechanism, and its release was principally driven by diffusion and secondarily by polymer erosion. The stress testing demonstrated that high temperature and humidity are potential risk factors affecting the quality of the bilayer tablets. In addition, the bilayer tablets showed a similar bioavailability to Moxatag® in beagle dogs. In conclusion, the results of the present study demonstrated for the first time the feasibility of developing an immediate- and extended-release formulation of amoxicillin for once-daily use using a bilayer tablet strategy. [ABSTRACT FROM AUTHOR]