Iranian Journal of Science and Technology, Transactions A: Science最新文献

Functional response is vital in understanding and controlling disease dynamics through mathematical modeling. This study introduces the Crowley-Martin (C-M) functional response in tumor-host cell interaction dynamics, which accounts for the handling time of healthy host cells in destroying tumor cells and the magnitude of interference among these cells. When both interference and handling time of healthy host cells in destroying tumor cells are zero, tumor cells are eradicated effectively. As these parameters increase, the system shifts to a state of coexistence. The complex dynamics of the model are explored by discretize the continuous model using Euler’s method. The local stability and bifurcation of the model for different parameter values are studied, and appropriate conditions are established. Numerical simulations validate the theoretical results of Flip and Neimark-Sacker bifurcation, revealing complex dynamical behaviors, including chaotic patterns, which suggest disease progression. Based on the chaos appearing in the bifurcation diagrams, we propose an optimal control strategy to control tumor cell growth by introducing chemotherapy drugs.

Nonlinear differential equations are crucial to models in natural and biological sciences, making them a vibrant and compelling area of research. Fractional differential equations are currently reformed and presented in various formats, establishing their core concepts within a mathematical framework and practical applications. The present work demonstrates the existence and uniqueness of solutions for Hilfer fractional pantograph differential equations with stochastic impulses utilizing fixed point theory. The Banach contraction principle indicates that the solution is unique, and the Lery-Schauder fixed point theorem examines if it exists. Furthermore, the qualitative behavior of the dynamical system has been investigated. Finally, it offers a theoretical implementation.

Radio signal blackout in communication from ground-based stations to fast moving space reentry vehicles and vice-versa is a vital problem in space research missions. Many mitigation solutions, including electrophilic liquid injection into the plasma sheath and creating the magnetic window, have already been proposed and tested successfully in real flights. In this paper after describing the conditions for plasma sheath formation around an entering space vehicle, using scattering matrix method (SMM) and Fresnel coefficients, we showed analytically that up to some injected dust concentration, the radio wave transmission through plasma sheath can be ameliorated and so the blackout period is relatively decreased.

This work investigates the effect of Ce doping in ZnO by sol–gel combustion method on its photocatalytic activity and optoelectronic application. XRD, TEM analysis confirmed the wurtzite hexagonal structure of ZnO. EDX analysis depicted the presence of Ce in addition to Zn and O. UV–Vis studies revealed a decrement in energy band gap on introduction of Ce. PL data analysis showed the existence of various defects which upgrades enhancement of visible emission via activation through diverse wavelengths. The photocatalytic activity of the synthesized nanoparticles was studied by evaluating the degradation of methylene blue (MB) under solar and methyl orange (MO) under xenon light irradiation. Zn_0.99Ce_0.01O showed an efficiency of 96.9% under solar irradiation compared to 41.5% using a light source for the same duration of exposure. Hence sunlight could be considered as the best light source for the elimination of dyes from the water sources in the environment. Moreover, the CIE coordinates of Zn_0.97Ce_0.03O were obtained to be (0.36, 0.38) with CCT of 4574 K at 325 nm which shows warm white light validating its application in household optoelectronic devices.

First, we establish some extended and refined results in the theory of viscosity solutions including a continuous dependence theorem, and a regularity result. Then, by investigating a certain type of partial differential equations, we expand the application of viscosity solutions to a broad range of higher-order partial differential equations. Finally, in the last section, we prove some corollaries that show the applicability of our results.

The Rudimentary Analysis of Edible Silver foil has been Investigated by a Magnetic Field (B)-supported LIBS. The Silver Plasma was Produced by Employing an Nd-YAG Pulsed Laser (100 mJ,1064 nm,) on the Surface of Silver foil in the Presence of B = 0.75 T, which Analyzed the Significant Enhancement in the LIBS Sensitivity by Detecting the Essential and Toxic Elements (C, Ag, Al, Fe, Ca, Cr, Si, Mg, Na) in Silver Plasma. The Enhancement Factor is up to four-fold and Optical Emission Intensity, Plasma Parameters like Plasma Temperature (T_e) and electron Number Density (n_e) were Enhanced in the Presence of a Magnetic Field (B). The Signal Enhancement in Silver Plasma was Ascribed to Magnetic Confinement and an Increase in Recombination rate after Relaxing the Plasma. Moreover, the Value of Thermal beta is Estimated Analytically (βt < 1) in this Study, which Confirms the Validity of Magnetic Confinement in all Samples. The Elemental Composition was Determined by the Calibration-Free LIBS (CF-LIBS) Approach with Zero Fields and B-field. The Result Revealed that Silver Foils were Fraudulently Adulterated by 25–35% Aluminum, and 0.8–1.08% Chromium, which Eventually Accumulates in the Human body via the food Chain Leading to high Risks to Human Health

In this study, we examined the potential ability of the sulfonated melamine–formaldehyde resin (SMFR) as an acidic heterogeneous catalyst in the multicomponent synthesis of 3, 4-dihydropyrimidine. The incorporation of sulfonic acid groups into the melamine–formaldehyde resin framework resulted in a highly active and recyclable catalyst, promoting reactions under mild and environmentally friendly conditions. Key advantages of this method include short reaction times, high product yields, and efficient catalysis with minimal catalyst loading. The synthesized compounds were structurally confirmed through FT-IR, ¹³C NMR, and ¹H NMR spectroscopy, demonstrating the efficiency and reliability of the catalytic system under green synthesis conditions.

Graphical Abstract

Let (V_3(z,f)= (3/4)z+(3/10)a_2z^2+(1/20)a_3z^3) and (sigma _3^{(alpha )}(z,f)=z+(2/(2+alpha ))a_2z^2+(2/[(2+alpha )(1+alpha )])a_3z^3) be the cubic polynomials representing, respectively, the 3rd de la Vall(acute{e})e Poussin mean and the 3rd Ces(grave{a})ro mean of order (alpha ; (alpha ge 0)) of a normalized analytic function (f(z) = z+sum _{k=2}^{infty } a_k z^k.) If (mathscr {K}) denotes the usual class of normalized convex univalent functions in the open unit disc ({mathbb {D}}) in the complex plane centered at the origin, we demonstrate that (V_3(z,f)prec sigma _3^{(alpha )}(z,f)) in (mathbb {D}) for all (fin mathscr {K}) and for all real numbers (alpha) satisfying (3le alpha le 19). For all (alpha ge 19,) we also identify a sharp real number (multiplier) (gamma (alpha )) such that (gamma (alpha )cdot V_3(z,f)prec sigma _3^{(alpha )}(z,f)) in (mathbb {D}) for all (fin mathscr {K}.) Here ‘(prec)’ denotes subordination between two analytic functions.

This article proposes a new formulation of the adaptive finite element and finite difference methods to obtain an approximate solution to the Riesz-Caputo space-time fractional partial differential equations. We propose the targeted algorithm for complexity addressing in one dimensional nonuniform meshes. The proposed technique uses a known gradient recovery method with optimal accuracy: the polynomial preserving recovery technique, and offers adaptivity. This procedure is based on extensive analytical results about error margins, stability criteria, etc. To emphasize its efficiency even more, the article gives numerous numerical examples showing the algorithm has advantages over the other numerical approaches. This shows the method’s efficiency and a useful implementation for these kinds of fractional partial differential equations posed in fractional calculus.

The purpose of this present article is to illustrate the approximation and related properties of Szász-Jakimovski-Leviatan type operators constructed using Beta functions. In this context, approximations are obtained by constructing a new class of Szász-Jakimovski-Leviatan Beta type operators, which are introduced through the Appell polynomials in Dunkl formulations. In the investigations, the approximation is studied in Korovkin’s and weighted Korovkin’s spaces involving local and global approximations. The rate of convergence is also obtained in terms of the weighted modulus of continuity, Lipschitz functions, Peetre’s K-functional, and some direct theorems. Consequently, in the final paragraph, approximations are studied through A-statistical convergence.