BEM FOR MODAL ANALYSIS OF 3-D ANISOTROPIC STRUCTURES

The boundary element method for the modal analysis of freevibration for 3-D anisotropic structures using particular solutionshas been developed. The complete polynomials of order two are used toconstruct the particular solutions for general anisotropic materials.The numerical results for 3-D free vibra- tion analysis of anisotropic cantilever beam by the method presented is in goodagreement with the results us- ing the Ritz technique. Foranisotropic materials, the numerical results calculated form theproposed method are in good agreement with the results from MSC.NASTRAN.

Scaffolds with anisotropic structure for neural tissue engineering

Nervous system injuries remain a great challenge due to limited natural tissue regeneration capabilities.Neural tissue engineering has been regarded as a promising approach for repairing nerve defects,which utilizes external biomaterial scaffolds to allow cells to migrate to the injury site and repair the tissue.Particularly,scaffolds with anisotropic structures biomimicking the native extracellular matrix(ECM)can effectively guide neural orientation and reconnection.Here,the advancements of scaffolds with anisotropic structures in the field of neural tissue engineering are presented.The fabrication strategies of scaffolds with anisotropic structures and their effects in vitro and in vivo are highlighted.We also discuss the challenges and provide a perspective of this field.

Preparation of Anisotropic MnO2 Nanocatalysts for Selective Oxidation of Benzyl Alcohol and 5-Hydroxymethylfurfural

Anisotropic MnO2 nanostructures,includingα-phase nanowire,α-phase nanorod,δ-phase nanosheet,α+δ-phase nanowire,and amorphous fl occule,were synthesized by a simple hydrothermal method through adjusting the pH of the precursor solution and using diff erent counterions.The catalytic properties of the as-synthesized MnO2 nanomaterials in the selective oxidation of benzyl alcohol(BA)and 5-hydroxymethylfurfural(HMF)were evaluated.The eff ects of micromorphology,phase structure,and redox state on the catalytic activity of MnO2 nanomaterials were investigated.The results showed that the intrinsic catalytic oxidation activity was mainly infl uenced by the unique anisotropic structure and surface chemical property of MnO2.With one-dimensional and 2D structures exposing highly active surfaces,unique crystal forms,and high oxidation state of Mn,the intrinsic activities for MnO2 catalysts synthesized in pH 1,5,and 10 solutions(denoted as MnO2-pH1,MnO2-pH5,and MnO2-pH10,respectively)were twice higher than those of other MnO2 catalysts in oxidation of BA and HMF.With a moderate aspect ratio,theα+δnanowire of MnO2-pH10 exhibited the highest average oxidation state,most abundant active sites,and the best catalytic oxidation activity.

Anisotropic thermoelectric transport properties in polycrystalline SnSe_(2)

It is reported that SnSe_(2) consisting of the same elements as SnSe, is a new promising thermoelectric material with advantageous layered structure. In this work, the thermoelectric performance of polycrystalline SnSe_(2) is improved through introducing SnSe phase and electron doping(Cl doped in Se sites). The anisotropic transport properties of SnSe_(2) are investigated. A great reduction of the thermal conductivity is achieved in SnSe_(2) through introducing SnSe phase, which mainly results from the strong SnSe_(2)–SnSe inter-phase scattering. Then the carrier concentration is optimized via Cl doping, leading to a great enhancement of the electrical transport properties, thus an extraordinary power factor of ^5.12 μW·cm^(-1)·K^(-2) is achieved along the direction parallel to the spark plasma sintering(SPS) pressure direction( P). Through the comprehensive consideration on the anisotropic thermoelectric transport properties, an enhanced figure of merit ZT is attained and reaches to ^ 0.6 at 773 K in SnSe_(2)-2% SnSe after 5% Cl doping along the P direction, which is much higher than ^ 0.13 and ^ 0.09 obtained in SnSe_(2)-2% SnSe and pristine SnSe_(2) samples, respectively.

Multi-functional Hollow Structures for Intelligent Drug Delivery

Multi-fountional hollow structures have emerged as promising platforms for intelligent drug delivery due to their unique properties,such as high loading capacities and programmed drug release.In particular,hollow multishell structures(HoMSs)with multilevel shell and space can regulate the molecular-level interaction between drugs and materials,so as to achieve the temporal-spatial order and sequential release of drugs.The anisotropic hollow structures can control the drug diffusion process by inducing the macroscopic interface flow through autonomous movement,realizing the targeted drug transport and release.In this paper,a key focus will be HoMSs with their temporal-ordered architectures and anisotropic hollow carriers with directional movement.Their synthesis mechanisms,structure-property relationships,smartly programmed drug delivery and biomedical applications will be discussed,providing insights into designing next-generation intelligent drug carriers.

Anisotropic phononic crystal structure with low-frequency bandgap and heat flux manipulation

This study presents a two-dimensional phononic crystal with heat flux manipulation and wide bandgaps of out-of-plane modes within the low-frequency range. The anisotropic matrix made of spiral-multilayered materials with different thermal conductivities, and the coating layer inserted with metal are designed for heat flux manipulation. Rubber-coated metal cylinders are periodically embedded in the anisotropic matrix to obtain the low-frequency bandgaps of out-of-plane modes. Numerical simulation is carried out to validate the heat and elastic characteristics of the spiral-multilayered anisotropic structure and reveal the effects of the laying angle and temperature on the bandgaps. Subsequently, a spiral-multilayered plate with periodic structures is studied, which shows an obvious vibration attenuation in the frequency ranges of the bandgaps and a deflected heat flux from the initial propagation direction. In the experimental investigation, the multi-phase spiral-multilayered anisotropic plate is simplified to a single-phase anisotropic plate made of aluminum. The characteristics of this type of anisotropic phononic crystal structure may pave the way for the design of a new kind of thermo-acoustic metamaterial serving in combined thermal and acoustic environments.

A New BEM for Fractional Nonlinear Generalized Porothermoelastic Wave Propagation Problems

The main purpose of the current article is to develop a novel boundary element model for solving fractional-order nonlinear generalized porothermoelastic wave propagation problems in the context of temperaturedependent functionally graded anisotropic(FGA)structures.The system of governing equations of the considered problem is extremely very difficult or impossible to solve analytically due to nonlinearity,fractional order diffusion and strongly anisotropic mechanical and physical properties of considered porous structures.Therefore,an efficient boundary element method(BEM)has been proposed to overcome this difficulty,where,the nonlinear terms were treated using the Kirchhoff transformation and the domain integrals were treated using the Cartesian transformation method(CTM).The generalized modified shift-splitting(GMSS)iteration method was used to solve the linear systems resulting from BEM,also,GMSS reduces the iterations number and CPU execution time of computations.The numerical findings show the effects of fractional order parameter,anisotropy and functionally graded material on the nonlinear porothermoelastic stress waves.The numerical outcomes are in very good agreement with those from existing literature and demonstrate the validity and reliability of the proposed methodology.

Complex band structures of 1D anisotropic graphene photonic crystal

The complex band structures of a 1D anisotropic graphene photonic crystal are investigated, and the dispersion relations are confirmed using the transfer matrix method and simulation of commercial software. It is found that the result of using effective medium theory can fit the derived dispersion curves in the low wave vector.Transmission, absorption, and reflection at oblique incident angles are studied for the structure, respectively.Omni-gaps exist for angles as high as 80° for two polarizations. Physical mechanisms of the tunable dispersion and transmission are explained by the permittivity of graphene and the effective permittivity of the multilayerstructure.

Synergistic fluorescent hydrogel actuators with selective spatial shape/color-changing behaviors via interfacial supramolecular assembly

Biomimetic intelligent polymeric hydrogel actuators with cooperative fluorescence-color switchable behaviors are expected to find great potential applications in soft robotics,visual detection/display,and camouflage applications.However,it remains challenging to realize the spatial manipulation of synergistic shape/color-changing behaviors.Herein,we report an interfacial supramolecular assembly(ISA)approach that enables the construction of robust fluorescent polymeric hydrogel actuators with spatially anisotropic structures.On the basis of this ISA approach,diverse 2D/3D soft fluorescent hydrogel actuators,including chameleon-and octopi-shaped ones with spatially anisotropic structures,were facilely assembled from two different fluorescent hydrogel building blocks sharing the same physically cross-linked agar network.Spatially control over synergistic shape/color-changing behaviors was then realized in one single anisotropic hydrogel actuator.The proposed ISA approach is universal and expected to open promising avenues for developing powerful bioinspired intelligent soft actuators/robotics with selective spatial shape/color-changing behaviors.

The Prey Capture Mechanism of Micro Structure on the Sarracenia Judith Hindle Inner Surface

Low friction surface has attracted considerable attention due to its potential application in various fields. As a typical carnivorous plant, Sarracenia Judith Hindle possesses unique slippery surface to capture prey especially in wet environment. In order to make clear the low friction mechanism, structural characterization was carried out and unique inclined micro-thorn structure was found on the inner wall surface. Micro-droplets harvest on the surface of the micro-thorn was discovered via the observation in wet environment. Friction force measurement was conducted by sliding the ants＇ footpad on the inner surface and polymer replica surfaces, which demonstrated that the friction force decreases on those surfaces in wet environment or inward direction. Further analysis manifested that the slippery inner surface grown with hierarchical micro-thorn structure leads to the friction decrease, and that is the fundamental mechanism for prey capture and retention in the pitcher of carnivorous plant Sarracenia Judith Hindle.

In-situ polymerization for mechanical strong composite actuators based on anisotropic wood and thermoresponsive polymer

Stimuli-responsive hydrogels hold an irreplaceable statue in intelligent actuation materials because of their reversible stretchability and excellent biocompatibility.However,the poor mechanical performance and complicated fabrication process of anisotropic structures severely limit their further applications.Herein,we report a high-strength thermoresponsive wood-PNIPAM composite hydrogel actuator with complex deformations,through a simple in-situ polymerization.In this composite hydrogel actuator,the anisotropic wood and the thermoresponsive PNIPAM hydrogel hydroel can work together to pro-vide bending and even other complex deformations.Owing to strong interfacial interaction,this actuator perfectly realized the combination of good mechanical properties(∼1.1 MPa)and fast actuation speed(∼0.9 s).In addition,by adjusting the orientation direction of wood,this actuator can achieve various complex deformations.Such composite hydrogel actuator could be a good candidate for intelligent appli-cations,such as intelligent actuators,smart valves,manipulators and even soft robots.

Anisotropic hemp-stem-derived biochar supported phase change materials with efficient solar-thermal energy conversion and storage

As cheap and renewable sources,the exploitation of biomass resources was of great value in phase change energy storage.In this study,hemp stems were converted into biochars with three-dimensional multi-level anisotropic pores through a temperature-controlled charring process,which were used as supports for polyethylene glycol(PEG6000)to form shape-stable composite phase change materials(ss-CPCMs).It is shown that the ss-CPCMs using anisotropic hemp-stem-derived biochar obtained at a carbonization temperature of 900℃as a support has high PEG6000 loading rate(88.62wt%),large latent heat(170.44 J/g)and favorable thermal stability owning to its high surface area and hierarchical pores.The biochar-based ss-CPCM also has good light absorption ability with a maximum solar-thermal conversion efficiency of 97.70%.In addition,the different thermal conductivities in the transverse and longitudinal directions of ss-CPCMs reflect the unique anisotropic structure.This work can not only improve the high-value utilization of biochars,but also provide the ss-CPCMs with excellent performance for solar-thermal conversion and storage systems.

Ionoprinting controlled information storage of fluorescent hydrogel for hierarchical and multi-dimensional decryption

Information storage and corresponding encryption/decryption are highly important owing to the prevalence of counterfeit activities and information leakage in the current age. Herein, we propose a novel method to store information via controllable ionoprinting onto fluorescent hydrogel for hierarchical and multi-dimensional decryption.Through incorporating pyrene moieties and carboxylic groups into polymeric hydrogel network, fluorescence changing and controllable shape deformation behaviors could be achieved and integrated by ionoprinting of Fe3+ions. The diffusion of Fe^3+ions into fluorescent hydrogel can quench the fluorescence of pyrene moieties, and chelate with carboxylic groups to generate anisotropic structures for shape deformation simultaneously. Thus, fluorescence quenching-based 2D information and actuation-based 3D information could be hierarchically decrypted when exposed to UV light and being put into water, respectively. Importantly, the stored information could be erased by replacing Fe^3+with H^+, which allows the fluorescent hydrogel as a recyclable information storage material. This work may provide new insights in designing and fabricating novel soft devices for hierarchical and multidimensional information encryption, against the rising problems of counterfeiting and confidential information disclosure.