Modern Physics Letters B

Polymer Nanocomposites (PNC) comprising polyvinylidene fluoride (PVDF)/Multi-walled Carbon Nanotubes (MWCNT) were studied. The structural composition and thermal stability were confirmed from XRD and DSC/TGA data, respectively. The extent of distribution of MWCNT in the PNC increases and the clustering of MWCNT also increases with an increase in the volume fraction of MWCNT ($f_{\mathrm{\text{MWCNT}}})$, as confirmed by FESEM. The PNC shows an insulator-to-metal transition (IMT), with both non-universal percolation threshold $(f_c)$ of $f_{\mathrm{\text{MWCNT}}}=0.006$ and scaling exponents $[s=0.36\pm 0.03,s^{\prime }=1.26\pm 0.1]$, respectively, attributed to adhesiveness/cold pressing and the higher aspect ratio/conductivity of MWCNT. Modulus spectroscopy confirms a non-Debye type universal relaxation behavior $(\beta =0.54)$ only for the percolative sample due to Maxwell–Wagner–Sillars/interfacial polarization, while only dipolar relaxation was probed or the samples below $f_c$. The $f_c$ with static effective dielectric constant $\sim 211$ and low tan $\delta$ may be suitable for charge storage applications.

The theme of this study is to investigate the impact of radiation with Thompson and Troian boundary slip on CNT-Fe₃O₄/kerosene oil (KO) hybrid nanofluid flow across a porous exponentially stretching sheet. The viscosity is considered to be temperature-dependent using Reynolds viscosity model. A comparative analysis is done for SWCNT-Fe₃O₄/KO and MWCNT-Fe₃O₄/KO. Methodology: The nonlinear partial differential equations (PDEs) are remodeled into non-dimensional ordinary differential equations (ODEs) using suitable similarity transformation. To solve the non-dimensional equations, the Legendre wavelet collocation technique (LWCT) is applied. The code is validated numerically as well as graphically with previous works and found to be in good agreement with them. Findings: It has been observed that thermal profiles are enhanced with the rise in radiation and heat generation. Additionally, in comparison, the velocity profile of MWCNT-Fe₃O₄/KO is found superior to SWCNT-Fe₃O₄/KO. It is observed that heat transfer (HT) rate is enhanced by 30.11% on elevating the volume fraction of Fe₃O₄ from 1% to 10% and is represented by a scatter plot.

A novel ring-core photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) is designed for ultra-low refractive index detection. A gold nanowire is coated on the outer surface of the PCF as a plasma material, greatly facilitating the manufacturing of the sensor. To achieve real-time detection, the analyte is located on the outside of the sensor. The mode coupling effect and main performance parameters are analyzed through finite element method. In addition, by optimizing several important structural parameters, the overall performance of the sensor has been greatly improved. The optimized sensor shows a maximum wavelength sensitivity of 26,000nm/RIU in the refractive index range of 1.14–1.26, maximum amplitude sensitivity of 300RIU${}^{-1}$, as well as minimum resolution of $3.85\times 10^{-6}$RIU. The PCF-SPR sensor with outstanding properties has great potential in applications such as oil logging, biosensing, and chemical monitoring.

This work is motivated by the importance of vertical vibration in nanofluids suspension, because of its wide applications in heat exchangers from one fluid to another, controlling the mixing in microvolumes, pharmaceutical industry, and engineering. The current study analyzes the effects of high-frequency vertical vibration on a horizontal Casson nanofluid layer heated from below saturated between rigid-rigid, rigid-free, and free-free boundary conditions. Field equations are derived by using time-average method, which describes the vibrational thermo-convection. These field equations are solved by utilizing linear stability analysis and Galerkin technique to obtain the thermal stability curve. By using this curve, the impacts of vertical vibration and physical governing factors on temperature profile are discussed. High-frequency vertical vibration is observed to have a stabilizing effect on Casson nanofluid suspension, thereby reducing thermo-convective heat transfer from one fluid to another. Stability threshold of vibrated suspension is increased approximately as $5.748\%$ and $81.937\%$ when $R_v\to 50$ and $R_v\to 100$, respectively. The significance of Brownian motion and thermophoretic force on convective heat transfer with vertical vibration is discussed. The resisting nature of Casson nanofluid on vibrational convective heat transfer is also tabulated.

A kind of acoustic metasurface (AMS) with multiple response frequency bands based on the replace method was proposed, which composed of six units, each containing three split hollow cubics (SHCs) (denoted as the AAA type of AMS). The simulation results demonstrated that the presented AMS can achieve the flexible modulation of the reflected wave direction. The AAA type of AMS had one response band, the AAC type of AMS had two different response bands, and the ABC type of AMS had three different response bands. Furthermore, the response bandwidth of the ABC type of AMS declined the most in the middle-frequency band, followed in the low-frequency band, and the least in the high-frequency band, when compared to the corresponding AAA type of AMS with single bandwidth. In addition, it was worth noting that the ABC type of AMS not only enlarged the manipulation direction of reflected acoustic wave, but also improved the effects of the wavefront distribution at the same frequency. This multiple band AMS will be beneficial for the application of architectural acoustics, and acoustic absorption and noise reduction.

In this work, we consider the results of studying the spectral distribution, the temperature dependence of photoconductivity, and the dependence of the spectral distribution of photoconductivity on the applied electric field of doped with rare earth elements GaTe single crystals in the temperature range of 30–300 K. As the temperature decreases to 30 K, the impurity peaks disappear, and the intense maximum shifts to the short wavelength region. The increase in impurity photoconductivity with increasing temperature is due to the thermooptical filling of acceptor levels with electrons and their further transition to the conduction band under the action of illumination. Such a temperature dependence of the photoconductivity is explained by the presence of acceptor levels in the band gap.

In nature, living organisms move in a collective state of aggregation, this collective motion is influenced by the nature of the environment, the obstacles refocused during the movement and the local interaction between individuals, this interaction is responsible for avoiding collision between each individual. In this paper, we study numerically the collective motion of self-organized organisms by expanding the Langevin dynamics, in which we have modeled the interaction between individuals by an elastic force. Modeling the interaction between individuals using an elastic force gives remarkable results. This interaction has an important effect if the individuals are dispersed a lot in space, but if a certain number of particles N is exceeded, this force is of no importance and the saturation velocity becomes constant. The results of the numerical simulation show that the average velocity of the individuals goes through a transient regime before reaching the permanent regime. Moreover, the results show that the system represents a transition from a nonequilibrium state to an equilibrium state, which is similar to a second-phase transition (paramagnetic/ferromagnetic) in the absence of the magnetic field; this phase transition is observable if the distance between two individuals is greater than a critical radius noted $R_c$.

In this paper, a triple-layer grating beam splitter with three-port output is designed. Through the combination of rigorous coupled-wave analysis (RCWA) and simulated annealing algorithms (SAA), the calculation and optimization of each parameter of the grating is carried out to make the diffraction efficiency of the grating meet the conditions. At the incident wavelength of 800nm, the diffraction efficiencies of 0th order and ±1st order under TE polarization are 31.6% and 31.4%, respectively. The diffraction efficiencies of 0th order and ±1st order under TM polarization are 32.7% and 32.5%, respectively. It can be seen that not only the total diffraction efficiency under TE polarization and TM polarization exceeds 90%, but also the uniformity of diffraction efficiency at each order exceeds 99%. Finally, the influence of grating parameters and incident wave characteristics on diffraction efficiency is discussed.

In this work, new varieties of unexpected scenarios for the solitons arising from the spatio-temporal dispersion ($1+1$)-dimensional Ito-equation (STDIE) are considered as an extension of the KdV (mKdV) type to higher order and usually employed to predict the rolling behavior of ships in regular sea. Moreover, they can describe the interaction process of two internal long waves specially the height of the water’s free surface above a flat bottom where $\mathrm{{\rm Y}}(x,t)$ is an analytic function. We will introduce these new unexpected and impressive scenarios for the solitons that emerged from this model for the first time in the framework of three distinct schemas. The three schemas that are employed for this target are the Paul-Painleve approach method (PPAM), the extended direct algebraic method (EDAM) and ($G^{\prime }$/G)-expansion method. Our obtained solitons are new compared with that achieved before by other authors who applied various schemas.

The catalyst surface was processed in the high-voltage electrical discharge device in oxygen environment. Continuous active oxide centers formed on the surface and complete filling of the surface with oxygen occur, and its thermo-physical properties, thermo-luminescence curves, scanning electron microscope and ESR spectrometers were studied. It was determined that the activity of the catalyst at values of the absorbed dose $D\le 21$kGy is many times higher than that of conventional catalysts. Thus, due to the sorption volume of the surface, the volume of the product formed in the liquid phase increases by 1.6 times.

In this work, the crystal structure of Leptothrix biosamples was studied using positron annihilation lifetime spectroscopy, MIKA modeling package and X-ray diffraction method. The structural analysis results showed that free cubic and orthorhombic phase Fe and trigonal Fe₂O₃ and cubic Fe₃O₄ phases were detected in Leptothrix biosamples. It has been determined that the concentration of cubic Fe₃O₄ phases in biosamples is higher than other phases. The theoretical bases of the regularity of distribution of hydrogen and oxygen atoms in the form of free and vacancies in the trigonal Fe₂O₃ and cubic Fe₃O₄ phases were calculated. On the other hand, the lifetime of vacancies in Fe, Fe₂O₃ and Fe₃O₄ structures has been determined.

This paper presents a performance analysis of indium-gallium-zinc-oxide (IGZO)- and pentacene-based top-gate-top-contact (TGTC) and bottom-gate-top-contact (BGTC) thin film transistors (TFTs). Extensive simulation has been performed to assess the performances in terms of threshold voltage, subthreshold slope, on-off current ratio, mobility, and figure of merit (FoM). Results indicate a trade-off between mobility and current ratio with respect to the permittivity of the dielectric layer, where tantalum oxide (Ta₂O${}_5)$ provides the optimum result in terms of FoM. The mobility of IGZO is significantly higher for both structures, whereas the current ratio for IGZO is higher than pentacene in the BGTC configuration. Comparing the structural configurations, Ta₂O₅-IGZO-based BGTC achieves $5.92\times$ and $41.8\times$ better mobility and current ratio, respectively, over TGTC structures. The threshold voltage of IGZO-based TFT is observed to increase with the permittivity of the dielectric in TGTC configuration but decrease in BGTC configuration. Meanwhile, the increase in oxide and active layer thicknesses causes a decrease in the threshold voltage. Moreover, both mobility and current ratio improve with a decrease in oxide or active layer thickness. Maximum mobility of 32.30cm²/Vs and a maximum current ratio of 7.54E+08 are achieved for Ta₂O₅-IGZO-based BGTC TFT with 10$\mu$m channel thickness and 5$\mu$m oxide thickness.