Modern Physics Letters B

Elastic wave metamaterials, such as phononic crystals (PnCs) always composed of several materials in terms of periodical structures, possess unique acoustic characteristic which can exhibit outstanding performance in forbidding wave propagation with some specific frequencies. In this paper, due to the thermal sensitivity of the thermally induced shape memory polymers (SMP) and period thermal fields, a tunable planar acoustic metamaterial which is constituent homogeneous is proposed and designed to realize the function of waveguides. A thin plate model composed of homogenous thermally induced SMP and adhered with a series of metallic films at the top boundary which plays the role of local heating sources is established. The homogenous plate can be transferred into acoustic metamaterial once the non-uniform period thermal fields are imported. Based on the Fourier law of heat conduction and finite element method (FEM), a two-dimensional numerical model via COMSOL Multiphysics is carried out to perform the in-plane mode band structures and transmission spectra. The results show that the bandgap will be effectively opened and change obviously as the injected heat flux increases. Furthermore, band structures of $7\times 1$ supercell with thermal defect are performed to reveal the design guideline of waveguides which is supposed to be the basis of line-type and L-type waveguides. The tunable characteristics of waveguides based on thermal fields with thermal defects are also discussed. These results may pave a new avenue for the design of tunable acoustic metamaterial composed of thermal sensitive material which own a prospect to be applied in area of acoustic waveguides.

Two-dimensional stanene is limited in its application in nanoscale optoelectronic devices due to its zero-bandgap. Based on first-principles calculations of density functional theory, the effects of adsorption of Be atoms with different coverages and torsional deformation on the structure, electricity, and optics of stanene are systematically investigated. The adsorption of Be atoms makes stanene have an adjustable bandgap, the surface state is successfully transformed from a zero-bandgap quasi-metal to a semiconductor with a maximum bandgap of 0.260 eV, the change in Be atom coverage causes a blueshift of the absorption and reflection peaks. Torsional deformation can effectively adjust the bandgap of stanene, which varies from 0.278 eV to 0.110 eV. Torsion enhances the maximum absorption peak of light. Stanene is expected to be a candidate material for designing new nanoelectronic devices.

It has become a priority of physics, chemistry, and material science to find new perovskite materials with environmentally friendly, excellent photoelectric properties and stable structures. This paper reports the design of lead-free double perovskite Rb₂KBiCl₆ and the effects of pressure on its structural, electronic, and optical properties. Also, its thermoelectric (TE) properties were systematically studied using a first-principles calculation based on density functional theory (DFT). It is found that Rb₂KBiCl₆ exhibits significant optical absorption in the ultraviolet range and that the band gap is an ideal choice for series photovoltaic applications and for use in wide-band-gap photovoltaic materials. At the same time, Rb₂KBiCl₆ shows excellent TE properties. In addition, the research results suggest a new way to adjust the crystal structure, optical band gap, and electronic structure of such materials.

In this paper, a simple two-dimensional (2D) photonic crystal (PhC) plus-shaped resonator is suggested to detect different cancer cells as well as urine glucose. A novel biosensor design is presented that features a plus-shaped PhC resonator capable of detecting cancerous cells in human skin, cervix, blood, adrenal glands and breast, as well as detecting glucose levels in human urine to diagnose the likelihood of diabetes. Our biosensor boasts of an impressive quality factor of 307 for cancerous skin cells and 670.6 for glucose concentration in the blood. In addition, the device offers a maximum sensitivity of 750nm/RIU for detecting various cancerous cells and 2420nm/RIU for glucose in human urine. By positioning the resonator and the waveguide in a way that enables light to resonate in the middle of the structure and pass to the output terminal, we were able to focus on the absorption rate rather than the transmission. As a result, the maximum glucose and cancerous cell absorption rates reach 87.1% and 89.8%, respectively. Our unique yet simple sensor structure offers exciting new possibilities for detecting different cancerous cells and glucose concentrations, while the impressive sensitivity and quality factor make it an exceptional candidate for a wide range of biosensing applications.

The new class of Tricarboxylate-Bismuth (TB)-based Metal Organic Frameworks (MOFs) was attempted, using the impressive capability of alkaline earth metal Bismuth (Bi), to realize more massive complex structures for real-world applications including supercapacitors, energy storage devices, biomedical imaging, drug delivery, fluorescence sensing and far-UVC applications. The grown structure and band gap of the TB-based MOFs samples were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and Ultraviolet-Visible Absorption Spectroscopy (UV-Vis spectra), respectively. The SEM observation identifies the TB-based MOFs nanosheet layered with orthorhombic structure, which shows strong agglomeration with a grain size of 668 nm. The EDS analysis indicates the presence of Bi-peaks as well as carbon peaks (organic linkers) in the grown samples. Furthermore, the peak of TB-based MOFs structure during the Raman spectroscopy was also confirmed. The optical band gap of the newly synthesized TB-based MOFs was estimated and the optical band gap ($E_g)$ approximately $\sim 5.45$eV was confirmed. These findings open the possibility of Bi-based MOFs for the applications in far-UVC emission range.

Plasmonic nanostructures have been demonstrated for their application in thin film solar cells to enhance absorption. Of particular concern is the novel design, enabling the broadband absorption enhancement. Here, we proposed and implemented a periodic corrugated Au nanomesh for broadband light absorption enhancement. By combining plasmon treatment of pre-stretched substrate and nanosphere lithography, the Au nanomesh on the nanocorrugation with different period has been realized. Compared to the planar nanomesh, the periodic corrugated nanomesh exhibits observable absorption enhancement at broad wavelength range, especially from 700nm to 1000nm, which is of significance in bring solar energy up to more utilization due to poor absorption of thin film solar cells at the near-infrared band. The enhancement attributes to the spatially geometry deformation of nanomesh supported more plasmonic resonance at the different adjacent frequency. Also, the absorption enhancement is relative to the period of corrugation, which caused by the variation of geometry deformation amplitude of nanomesh. This periodic corrugated metallic nanomesh provides an alternative nanostructured electrode to broadband absorption enhancement for thin film solar cell application.

In numerous real-world applications, transverse vibrations of beams are nonlinear in nature. It is a task to solve nonlinear beam systems due to their substantial dependence on the 4 variables of the system and the boundary conditions. To comprehend the nonlinear vibration characteristics, it is essential to do a precise parametric analysis. This research demonstrates an approximation solution for odd and even nonlinear transverse vibrating beams using the Laplace-based variation iteration method, and the formulation of the beams depends on the Galerkin approximation. For the solution of the nonlinear differential equation, this method is efficient as compared to the existing methods in the literature because the solutions exactly match with the numerical solutions. The Laplace-based variation iteration method has been used for the first time to obtain the solution to this important problem. To demonstrate the applicability and precision of the Laplace-based iteration method, several initial conditions are applied to the governing equation for nonlinearly vibrating transverse beams. The natural frequencies and periodic response curves are computed using Laplace-based VIM and compared with the Runge–Kutta RK4 method. In contrast to the RK4, the results demonstrate that the proposed method yields excellent consensus. The Lagrange multiplier is widely regarded as one of the most essential concepts in variational theory. The result obtained are displayed in the table form.

Highlights

The highlights of the solution of the Euler–Bernoulli beam equation with quintic nonlinearity using Lagrange multiplier are:

• 1.Introducing the constraint of the boundary conditions into the equation using Lagrange multipliers.
• 2.Formulating the equations for the Lagrange multipliers and the deflection of the beam.
• 3.Solving the resulting system of algebraic equations using numerical methods.
• 4.Obtaining the deflection of the beam as a function of its length and the applied load.
• 5.Analyzing the behavior of the beam under different loads and boundary conditions.

In this work, we study the influence of the temperature on the mechanism of current transfer in the reverse branch of the current–voltage (I–V) characteristics of n-CdS/p-CdTe heterostructures. The study of the heterostructure, using the technique of on energy-dispersive X-ray analysis, showed that a layer of CdS_xTe${}_{1-x}$ is formed at the boundary of the heterojunction with a varying composition, being equal $x\approx 0.48$ from the side of CdS and $x\approx 0.02$ from the CdTe side. In the studied range of the temperatures and bias voltage, the current-voltage characteristics are described well by a power law $J=A{V}^{\alpha }$, where the exponent $\alpha$ changes with the temperature and voltage. Under the influence of the temperature and charge carrier concentration, the mechanism of current transfer in the structure changes from exclusion ($\alpha \approx 0.5$) to ohmic ($\alpha \approx 1$), and then goes to injection ($\alpha \approx 2$). The inhomogeneous intermediate CdS_xTe${}_{1-x}$ i-layer at the boundary of the n-CdS/p-CdTe heterostructure is characterized by the presence of metastable states that rearrange at high temperatures and certain charge carrier concentrations. As a result of this, the exclusion slows down and electrons are injected from the rear molybdenum contact.

An analysis is carried out for the free convection of magneto-micropolar liquid via a stretching surface for the inclusion of thermal radiation and chemical reaction. The transverse magnetic field is employed on the normal direction of flow with the impact of Peclet number relating to thermal and solutal transfer profiles. Referring to the current applications in several engineering problems, industrial applications, and more importantly the peristaltic pumping processes, blood flow phenomena, etc. the role of micropolar fluid is significant. Therefore, the objective of thismodel is to develop by incorporating thermal radiation which has several applications in aforesaid areas. However, the proposed model is solved analytically using the differential transform method (DTM) and prior to that transformation to ordinary system is obtained by using similarity transformations. The characteristic of various physical components associated with the governing equations is deployed graphically. The analysis of these parameters is described briefly in the discussion section. Further, a statistical approach response surface methodology (RSM) is used to optimize the heat transfer rate for the factors such as magnetic parameter, thermal radiation, and Peclet number.

In this paper, we propose a novel, simple and accurate analytical study based on nonlocal elasticity theory to forecast small-scale effects on the radial vibration of anisotropic gold nanospheres submerged in viscoelastic fluid (VEF). Eringen’s model is used to determine the motion equation for anisotropic nanospheres, with the fluid assumed to be viscoelastic and compressible. The frequency equation is derived by imposing the fluid-nanosphere interface continuity conditions. A comparison with the literature results is conducted to demonstrate the validity and correctness of this analysis, which indicates a very good agreement. The importance of small-scale effects in the radial vibration, which need to be included in the nonlocal elasticity model of submerged nanospheres, is eventually revealed by numerical examples. It is discovered that the nanosphere size, nonlocal parameter, and glycerol–water mixture have a significant impact on the vibration behaviors. Our results show that the small scale is crucial for the radial vibration of gold nanoparticles when the gold nanosphere is smaller than $5.5\mathrm{\text{nm}}$. Thus, the resulting frequency equation is very useful to interpret experimental measurements of the vibration characteristics of submerged gold nanospheres in VEF.

The ballistic deposition model of rod-like particles with power-law distributed noise is studied by the Monte Carlo simulation. In this modified model instead of particles with fixed unit sizes, vertical rods whose length follows the power-law distribution $P(l)\sim l^{-(\mu +1)}$ are deposited, where $\mu$ denotes the power-law strength exponent. This deposition leads to porous rock structures with varying porosity and conductivity. The time evolution of the surface roughness and the porosity of the resulting structures are studied. The conductivity of the structures is calculated using the parallel resistors in the percolation model using a random walk algorithm. Finally, we discuss the relation between porosity, conductivity and the strength exponent of the power-law noise. The results show that the surface roughness increases as a pseudo-step function versus deposition time for $\mu =1$, which leads to an observable reduction in porosity and conductivity. By increasing the $\mu$ exponent, the growth exponent of $\beta =0.33\pm 0.02$ for the Gaussian model appears. The conductivity increases as $\sigma ={\sigma }_{0}exp(\frac{\mathrm{\Phi }}{\phi })$ versus porosity, $\mathrm{\Phi }$, and remains constant for $\mu \ge {\mu }_c=5$ which the value of ${\mu }_c=5$ has been identified for BD.

We present a strong coupled quantum dot-nanomechanical resonator system and investigate its nonlinear optical properties using optical pump-probe technology. The process of evolution of the nonlinear Kerr spectrum is studied for different resonator frequencies under low temperature and room temperature, respectively, and the results indicate that even at room temperature the nonlinear Kerr spectrum can still be resolved. In addition, we further theoretically propose a room temperature nonlinear optical mass sensing scheme based on the hybrid nanoresonator system. When the masses of external nanoparticles (such as biomolecules including baculovirus, coronavirus, DNA, etc.) are attached to the nanomechanical resonator, the resonance frequency shift caused by nanoparticles can be measured by nonlinear Kerr spectrum, and then the mass of nanoparticles can be determined. The hybrid coupled nanoresonator system will have potential applications in ultra-sensitive and high-resolution mass sensors.