Thermal buckling analysis of moderately thick functionally graded annular sector plates

In this article, thermal buckling analysis of moderately thick functionally graded annular sector plate is studied. The equilibrium and stability equations are derived using first order shear deformation plate theory. These equations are five highly coupled partial differential equations. By using an analytical method, the coupled stability equations are replaced by four decoupled equations. Solving the decoupled equations and satisfying the boundary conditions, the critical buckling temperature is found analytically. To this end, it is assumed that the annular sector plate is simply supported in radial edges and it has arbitrary boundary conditions along the circular edges. Thermal buckling of functionally graded annular sector plate for two types of thermal loading, uniform temperature rise and gradient through the thickness, are investigated. Finally, the effects of boundary conditions, power law index, plate thickness, annularity and sector angle on the critical buckling temperature of functionally graded annular sector plates are discussed in details.     

In Silico Evaluation of Hexamethylene Amiloride Derivatives as Potential Luminal Inhibitors of SARS-CoV-2 E Protein

The coronavirus E proteins are small membrane proteins found in the virus envelope of alpha and beta coronaviruses that have a high degree of overlap in their biochemical and functional properties despite minor sequence variations. The SARS-CoV-2 E is a 75-amino acid transmembrane protein capable of acting as an ion channel when assembled in a pentameric fashion. Various studies have found that hexamethylene amiloride (HMA) can inhibit the ion channel activity of the E protein in bilayers and also inhibit viral replication in cultured cells. Here, we use the available structural data in conjunction with homology modelling to build a comprehensive model of the E protein to assess potential binding sites and molecular interactions of HMA derivatives. Furthermore, we employed an iterative cycle of molecular modelling, extensive docking simulations, molecular dynamics and leveraging steered molecular dynamics to better understand the pore characteristics and quantify the affinity of the bound ligands. Results from this work highlight the potential of acylguanidines as blockers of the E protein and guide the development of subsequent small molecule inhibitors.     

Benchmark solution for free vibration of functionally graded moderately thick annular sector plates

In the present article, an exact analytical solution for free vibration analysis of a moderately thick functionally graded (FG) annular sector plate is presented. Based on the first-order shear deformation plate theory, five coupled partial differential equations of motion are obtained without any simplification. Doing some mathematical manipulations, these highly coupled equations are converted into a sixth-order and a fourth-order decoupled partial differential equation. The decoupled equation are solved analytically for an FG annular sector plate with simply supported radial edges. The accurate natural frequencies of the FG annular sector plates with nine different boundary conditions are presented for several aspect ratios, some thickness/length ratios, different sector angles, and various power law indices. The results show that variations of the thickness, aspect ratio, sector angle, and boundary condition of the FG annular sector plates can change the vibration wave number. Also for an FG annular sector plate with one free edge, in opposite to the other boundary conditions, the natural frequency decreases with increasing the aspect ratio for small aspect ratios. Moreover, the mode shape contour plots are depicted for an FG annular sector plate with various boundary conditions. The accurate natural frequencies of FG annular sector plates are presented for the first time and can serve as a benchmark solution.     

Study of Structural,Electrical and Optical Properties of (200)-Oriented CdTe Thin Films Depending on the Post-deposition Low Temperature

Cadmium telluride nanoparticles (CdTe NPs) have been synthesized by a sonochemical technique, deposited on glass and quartz glass at 100°C and 2.7?×?10^?6 kPa and then studied by analyzing the x-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), current–voltage test (I–V) and scanning electron microscopy (SEM). The XRD results indicated the formation of a strong preferential (200) orientation of CdTe with a cubic zinc-blende structure on both substrates. In order to show the effect of heating on the structure and optical properties of the prepared thin films, they were annealed at temperatures of 50°C, 70°C and 100°C for 1 h. It was found that the grain size in this orientation increases with the increase of the temperature. In addition, the obtained optical band gap energies by UV–Vis measurements were in the range of 1.46–1.53 eV. The electrical properties of the prepared films were observed to increase with annealing using I–V measurements. The thin films were also found to be uniform with a small particle size, as revealed by SEM.

     

Robust closed-loop global supply chain network design under uncertainty: the case of the medical device industry

Improving performance of global supply chains requires careful consideration of various factors including distance from markets, access to resources, exchange and tax rates, import tariffs, and trade regulations. In this paper, a comprehensive optimization model is proposed to maximise the after-tax profit of a closed-loop global supply chain for medical devices under uncertainty. The uncertainty of the decision-making environment is modelled using the budget of uncertainty concept in interval robust optimization. International financial issues due to the Economic Cooperation Organisation Trade Agreement as well as national regulations including transfer pricing limitations, exchange rates, tax rates, and import tariffs are considered. The proposed model considers various realistic assumptions pertaining to medical device supply chains such as multiple products, multiple periods, multiple echelons, and limited warehousing lifetime. In addition, reverse flows of perished and defective products are considered to address environmental concerns and customers’ requirements as well as to gain economic advantages. To tackle this problem, an efficient memetic algorithm is developed that incorporates adaptive variable neighbourhood search as its local search heuristic. Computational results demonstrate the efficiency of the proposed model in dealing with uncertainty in an agile manufacturing context. In addition, several managerial insights are discussed based on the results.     

Enhancement of mechanical properties of a soft magnetic Fe-based metallic glass

In this study, the effect of non-isothermal partial crystallisation on microstructure, and mechanical and magnetic properties of (Fe_0.9Ni_0.1)₇₇Mo₅P₉C_7.5B_1.5 BMG was investigated. Microstructural characterisations revealed that there was a phase separation in the as-cast BMG. Formation of nano-crystalline phases first occurred in the separated amorphous phase during initial stages of crystallisation process and then continued in the matrix phase. The nanocrystalline/amorphous matrix composite exhibited higher mechanical and magnetic properties compared to those of the as-cast BMG.     

Optimization of chemical activation of cotton fabrics for activated carbon fabrics production using response surface methodology

Abstract

The preparation of activated carbon fabric (ACF) from cotton fabric treated with phosphoric acid (H₃PO₄) was optimized using the response surface methodology (RSM). Experimental activation variables including; impregnation ratio, heating rate, activation temperature, and activation time were optimized based on the responses evaluated (adsorption capacity, yield of the produced ACF). The operation conditions for obtaining the ACFs with the highest the adsorption capacity and process yield were proposed. Optimized conditions were: impregnation ratio of 2, heating rate of 7.5 °C min^?1, the activation temperature of 500 °C, and the activation time of 30 min. The ACFs produced under optimized conditions were characterized by scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDX). The surface area and pore volume of carbon nanostructures were characterized by nitrogen adsorption isotherm at 77 °K using BET method. The obtained results showed that the produced ACFs have developed porous structure, fabric shape, BET surface area (690 m²/g) and total pore volume (0.3216 cm³/g), and well-preserved fibers integrity.     

On‐Chip Fabrication of Paclitaxel‐Loaded Chitosan Nanoparticles for Cancer Therapeutics

The use of solvent‐free microfluidics to fine‐tune the physical and chemical properties of chitosan nanoparticles for drug delivery is demonstrated. Nanoparticle self‐assembly is driven by pH changes in a water environment, which increases biocompatibility by avoiding organic solvent contamination common with traditional techniques. Controlling the time of mixing (2.5–75 ms) during nanoparticle self‐assembly enables us to adjust nanoparticle size and surface potential in order to maximize cellular uptake, which in turn dramatically increases drug effectiveness. The compact nanostructure of these nanoparticles preserves drug potency better than previous nanoparticles, and is more stable during long‐term circulation at physiological pH. However, when the nanoparticles encounter a tumor cell and the associated drop in pH, the drug contents are released. Moreover, the loading efficiency of hydrophobic drugs into the nanoparticles increases significantly from previous work to over 95%. The microfluidic techniques used here have applications not just for drug‐carrying nanoparticle fabrication, but also for the better control of virtually any self‐assembly process.