Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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 Iranian Journal of Science and Technology, Transactions A : ScienceNumber of Followers: 0      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1028-6276 - ISSN (Online) 2364-1819 Published by Springer-Verlag  [2467 journals]
• Dynamical Density of Two-Dimensional Dusty Plasmas

Abstract: Abstract Equilibrium molecular dynamics (EMD) simulation is employed to investigate the dynamical structure factors (DSFs), S(k, ω), of two-dimensional (2D) dusty plasmas over a broad series of plasma conditions of screening length (κ) and plasma coupling (Γ). Effect of changing wave vectors (k = 2π/L) on dynamical density S(k, ω) is measured with various arrangements of plasma parameters (Γ, κ). Reported results have been checked for the effect of various wave numbers on dynamical density (DSFs) S(k, ω) algorithm with diverse arrangement of (Γ, κ) parameters. The present investigations of dynamical density [S(k, ω)] illustrate that the amplitude and frequency of oscillation of the dust particle are varied with increasing Γ. The present study illustrates that the amplitude of oscillation of the plasma dynamical density nearly remains constant and slightly increases by an increase in N and κ, respectively, and amplitude of oscillation also influences with increasing of k. New findings show the modes of amplitude spectrum of S(k, ω) switch from damping spectra to damped oscillation and nearly sinusoidal mode as advancing plasma coupling. The reported forms of amplitude spectrum of plasma dynamical density shift to higher Γ; however, there is no significant change in modes of oscillation with an increment in κ and N. Results show that the plasma dynamical density S(k, ω) more fluctuates at extreme values of k and Γ, but it becomes less pronounced at large values of N. New outcomes of EMD are found to be more reliable, efficient and are in satisfactory agreement with previous available theoretical, experimental, and numerical results.
PubDate: 2022-11-28

• Dynamical Analysis of COVID-19 Model Incorporating Environmental Factors

Abstract: Abstract The continuing coronavirus pandemic has come up with considerable questions in front of the world. Presently, India is among concerned countries in Asia. Even though the recovery rate is more than the death rate, it is affecting human lives and experiencing losses to the market. Several methods were employed to study the spread of novel coronavirus. Mathematical modeling is one of the prominent techniques to evaluate the dynamics of novel coronavirus. In this work, we extend the mathematical model SEIAQRDT by incorporating environmental transmission to analyze the transmission of coronavirus in India. The notable aspect of the model incorporates asymptomatic population, quarantine individuals, and environmental transmission factors. These factors have enormous significance in the ongoing COVID-19 outbreak. The basic reproduction number $${{\varvec{R}}}_{0}$$ is calculated theoretically. Bifurcation analysis of $${{\varvec{R}}}_{0}$$ is also done analytically. The existence and stability analysis of disease-free equilibrium (DFE) and endemic equilibrium (EE) points are established. The impact of environmental factors in spreading COVID-19 pandemic is deliberated. The case study for India and Italy is presented and compared with real data, and the results are in accordance with the real situation.
PubDate: 2022-11-28

• The Trend of IgG and IgM Antibodies During 6-Month Period After the
Disease Episode in COVID-19 Patients

Abstract: Abstract SARS-CoV-2 is a newly emerged coronavirus that has been widely transmitted since late 2019. It has caused a pandemic and infected roughly 450 million people globally.Hitherto, there is no approved anti-COVID-19 treatment, and vaccination is the only experienced preventive strategy. It mainly promotes the immune system, which is vital as a barrier against COVID-19. Humoral immunity (antibody-mediated immunity), among the various functions of the immune system against the coronavirus, plays an outstanding role in preventing infection. Consequently, we intended to assess IgG and IgM antibodies, 3 and 6 months after infection, to trend their titer and see how long COVID-19 antibodies remained in the human body. According to the research-designed criteria, only 98 patients out of 4500 suspected cases of SARS-CoV-2 infection remained for analysis. Blood samples were taken in three time periods (Day Zero (T0), 3 and 6 months post-infection) and examined for COVID-19’s IgG and IgM antibodies titration using the ELISA platform. Though both IgG and IgM were still detectable for some subjects at the end of the period, the decline in their levels (from 14.45 ± 5.88 to 2.52 ± 2.33 for IgG [85% decline of antibody titer] and 8.3 ± 0.99 to 0.37 ± 0.14 for IgM [95.5% decline of antibody titer]) was statistically significant (P value 0.0001). There was no correlation between gender and IgG and IgM levels. Although the levels of both antibodies were overall higher in the senior group (≥ 60 years old), statistical analysis showed a significantly higher level just for IgM in this group (P value: 0.005). Following the results, although anti-SARS-CoV-2 IgM and IgG antibodies can persist in the blood for 6 months post-infection, their levels steeply declined over time. Therefore, relying on humoral immunity as a trustworthy barrier against SARS-CoV-2 infection calls for more extensive research.
PubDate: 2022-11-28

• Molecular Identification of Biofilm-Forming Marine Bacterial Strains
Isolated from Different Substrates of Mangrove Habitat

Abstract: Abstract Marine biofilms formed on submerged surfaces have major environmental and economic consequences, including the subsequent settlement of macrofoulers and biofouling formation. In marine aquaculture, biofouling is one of the main obstacles of sustainable production and instrument usage. The purpose of this study was to characterize the phylogenetic diversity of biofilm-forming bacteria examined on fishing nets and compare it with bacterial communities developing on the trunk of plants associated with a mangrove forest along the Persian Gulf. 16S rRNA amplicons were sequenced for 35 isolates from both of the surfaces samples studied here, of which 32 isolates showed high biofilm activities. The findings confirmed high diversity showing the predominance of γ-proteobacteria (74%) with five genera, Vibrio, Alteromonas, Pseudoalteromonas, Salinimonas and Bacterioplanes. Generally, Vibrio, Bacillus, Alteromonas and Salinimonas genera were identified on both fishing nets and trunk of plants. The genera of Tenacibaculum, Oceanobacillus and Fictibacilluse were only observed on plant trunk surfaces, while the genera of Bacterioplanes, Mesoflavibacter and Micrococcus were only isolated from fishing net surfaces. A list of marine biofilm-forming bacteria and their classification was presented for the first time in the mangrove ecosystem of the northern Persian Gulf, which should be followed by further studies on the chemical composition of biofilm-associated cues that restrain the settlement of macrofoulers as the first step to develop antifouling coatings.
PubDate: 2022-11-25

• MASS Spectrum of Heavy Quarkonium for Combined Potentials (Modified
Kratzer Plus Screened Coulomb Potential)

Abstract: Abstract In this work we combined two potentials modified Kratzer plus screened Coulomb potential. The result of the combination is used in the study of heavy quarks. The bound state energy spectra are derived by solving the radial Schrödinger equation (SE) with the modified Kratzer plus screened Coulomb potential. The mass spectra of heavy quarkonium systems (Charmonium and Bottomonium) are calculated using the energy spectra expression. The numerical results are consistent in comparison with the experimental values and studies of similar research published in the literature. Plots of mass spectra variations for various potential parameters are also shown for various quantum mechanical states.
PubDate: 2022-11-25

• On the Functorial Properties of the p-Analog of the
Fourier–Stieltjes Algebras

Abstract: Abstract In this paper, some known results about the functorial properties of the Fourier–Stieltjes algebra, B(G), will be generalized. First of all, the idempotent theorem on the Fourier–Stieltjes algebra will be promoted and linked to the p-analog one. Next, the p-analog of the $$\pi$$ -Fourier space introduced by Arsac will be given, and by taking advantage of the theory of ultrafilters, the connection between the dual space of the algebra of p-pseudofunctions and the p-analog of the $$\pi$$ -Fourier space will be fully investigated. As the main result, one of the significant and applicable functorial properties of the p-analog of the Fourier–Stieltjes algebras will be achieved.
PubDate: 2022-11-23

• Molecular Dynamics Simulation Study on the Effect of Oxali-Palladium as a
Catalytic Inhibitor of Human Topoisomerase IIα

Abstract: Abstract Among the many anticancer agents targeting topoisomerase IIα enzyme, palladium (II) analogues have gained in popularity as a promising enzyme inhibitor. In this article, molecular docking method and molecular dynamics (MD) simulations were employed to study the mechanism through which oxali-palladium (oxali-Pd) inhibits the enzymatic activity of human topo IIα. The results of docking simulation confirm the inhibitory effects of oxali-Pd on the catalytic core of topoisomerase IIα enzyme through a non-competitive process. Also, it is suggested that oxali-Pd might intercalate within the DNA bases according to the topo IIα dynamicity as well. The results of MD simulations reveal that oxali-Pd is surrounded by Arg713, Ser714, Lys723, GLN726, Ser 763, Met766, Thr767, Asn770, Leu771, Glu854, Gly855, and Arg929 residues of protein. The average value of ΔGsolv is about − 93.1 kJ.mol−1 for protein and − 95.1 kJ.mol−1 for complex. The average values of Coulombic and Lennard–Jones interaction energies are calculated to be about − 78.1 ± 18.9 and − 81.8 ± 10.2 kJ.mol−1, respectively. These interaction energy values demonstrate the both electrostatic and van der Waals forces are important in complex formation between topo IIα protein and oxali-Pd molecule. Therefore, based on the data obtained from this study, oxali-Pd acts as a catalytic inhibitor of human topo IIα and is not a poison to the enzyme.
PubDate: 2022-11-22

• Carbon Nanotubes: Smart Materials for the Active Elimination of
Electromagnetic Interference

Abstract: Abstract Single- and multi-layered composites of carbon nanotubes, with various weight percent, were fabricated to evaluate their electromagnetic interference shielding effect. Carbon nanotubes of two different lengths were tested for the selection of best nano-fillers as well as fillers for high microwave absorption. Our findings confirmed that longer multi-walled carbon nanotubes can be used for electromagnetic interference shielding where the shielding mechanism was found to be dominated by absorption in the microwave frequency region (2–18 GHz). Long carbon nanotubes-based composites show good electromagnetic wave absorption performance (reflection loss $$\approx 37$$ db) at high frequencies and reveal a broader bandwidth for microwave absorption. The mechanical properties, i.e., tensile strength, hardness, and electrical conductivity, were also improved with the incorporation of multi-walled carbon nanotubes. The measured absorption values, bandwidth, and tensile strength are believed to find attractive applications in the effective electromagnetic interference shielding and reduction of a radar signature. The observed results combined with the advantages of lightweight and corrosion resistant highlight the attractiveness of carbon nanotubes as shielding materials for commercial applications.
PubDate: 2022-11-21

• Mittag–Leffler Stability of Impulsive Nonlinear Fractional-Order
Systems with Time Delays

Abstract: Abstract Stability analysis of impulsive nonlinear fractional-order system (FOS) is discussed. First, the existence and uniqueness of solutions for FOS is discussed with help of fixed point theory. The nonlinear system is considered with a constant time delay and impulsive effects. Then, novel sufficient conditions to prove the Mittag–Leffler stability (MLS) of FOS are established by using well known mathematical techniques. Also, the results are extended to present finite-time MLS conditions for considered nonlinear FOSs. Finally, examples are given to show the validity of the derived results.
PubDate: 2022-11-19

• Stability and Bifurcation Analysis of Tumor–Macrophages Response Model
and Inhibitory Role of Treg Cells

Abstract: Abstract In this research paper, we propose a four-dimensional tumor–macrophages response model to study the role of Treg cells in the growth and dynamics of the model. The system of four nonlinear ordinary differential equations defines the proposed model, which represents the population growth of tumor cells, $$M_{1}$$ type of macrophages, $$M_{2}$$ type of macrophages, and Treg cells. The qualitative properties of the model are discussed including the existence, uniqueness, and positivity of solutions of the model. To convert the proposed model into its discrete counterpart, the piecewise constant argument method is applied. Linearization and stability analysis is also performed on the proposed model as well as on its discrete counterpart. The local asymptotic stability analysis on both the models is investigated at four biologically feasible equilibrium points. To discuss the emergence of bifurcation at the positive endemic equilibrium point, explicit criteria of Neimark–Sacker bifurcation analysis are implemented on the discrete counterpart of the model. Moreover, numerical simulation is also performed to illustrate the theoretical results numerically as well as graphically.
PubDate: 2022-11-16

• A Robust Analytical Method for Regularized Long Wave Equations

Abstract: Abstract The approximate solutions of regularized long wave (RLW) equations have been discussed here. According to the RLW equations, two solitary waves can pass through each other with reduced amplitude and produce secondary waves. RLW equations also model basic ocean engineering and research phenomena, such as shallow-water waves with long wavelengths and small amplitudes. An efficient analytical method known as the Aboodh transform homotopy perturbation method (ATHPM) has been utilized to examine RLW problems. The suggested method combines two effective techniques, the Aboodh transform and the homotopy perturbation method, to obtain accurate and approximate solutions to RLW equations. The outcome demonstrates that the ATHPM is extremely powerful, efficient and straightforward.
PubDate: 2022-11-15

• Effects of Treatment and Pre-treatment of Ethanolamine on Production of
Metabolites in Haematococcus pluvialis

Abstract: Abstract Haematococcus Pluvialis (H. pluvialis) is a microalga of freshwater which is a rich source of carotenoid. The astaxanthin, a type of carotenoid and antioxidant, has many health benefits. It has roles in healthier skin, endurance, heart health, joint pain relief and even can act as a super-antioxidant in cancer treatment. Optimizing physiological parameters of H. pluvialis can be a suitable method for increasing metabolites and producing astaxanthin. In order to improving the growth, pigments, proteins and carbohydrates in H. pluvialis, we used the influence of different concentration of ethanolamine by two methods of treatment and pre-treatment on its green and red phases. In the green phase, the ethanolamine treatment and pre-treatment increased all measured parameters on cells. The ethanolamine treatment also improved the amount of carotenoids and carbohydrates in red cells, but the amount of proteins and dry weight decreased in green cells. The ethanolamine pre-treatment did not have significant effects on dry weight of red cells, while increased the amounts of carotenoids, carbohydrates, and proteins. Moreover, it has effects on xanthophyll and increased the amount of astaxanthin. These results showed that ethanolamine has a high ability for improving signaling pathways of metabolites in H. pluvialis.
PubDate: 2022-11-11

• Improved Spectroscopic Characterizations of Laser-Induced Soil Plasma
Under Magnetic Effect at Various Laser Fluences

Abstract: Abstract This study investigates the impact of applied magnetic field on laser-induced breakdown spectroscopic emissions of river soil at various laser fluences. The soil samples were pelletized, and its plasma was generated by employing Nd: YAG laser (1064 nm, 8 ns) on the surface of samples in the presence of the magnetic field of 0.75 T at different laser fluences (47–96 J/cm2), which explore the significant improvement in the LIBS sensitivity by detecting trace elements (As, Mn, Cr, Ti, Co, Ba) with better signal-to-noise ratio. The emission signal enhancement up to fivefold and higher values of plasma parameters like electron temperature (Te) and electron number density (ne) is noticed with the magnetic field. Moreover, these parameters also show an increasing trend as a function of laser fluence with optimum values at a laser fluence of 80 J/cm2. The magnetic field-assisted LIBS provides better detection of toxic metals and more confined and repeatable plasma, which is confirmed by the plasma parameter βt < 1 determined in this work. Furthermore, the threshold laser fluence for soil samples was determined to be 7 J/cm2 and 13 J/cm2 with and without magnetic fields, respectively. The emission signal enhancement is accredited to the magnetic confinement of the soil plasma and has pivotal scope in the improvement in LIBS sensitivity.
PubDate: 2022-11-07

• Relations Between Almost n-Jordan Homomorphisms and Almost n-Homomorphisms

Abstract: Abstract Let A and B be topological algebras equipped with separating sequences of submultiplicative seminorms. For $$n\in \mathbb {N}$$ , $$n\ge 2$$ , we investigate under what conditions an almost n-Jordan homomorphism $$T:A\rightarrow B$$ is an almost n-homomorphism. We also study the automatic continuity of almost n-Jordan homomorphisms and almost n-homomorphisms. Finally, we present some results concerning additive n-Jordan homomorphisms on rings.
PubDate: 2022-11-02

• Collocation Method for Solving Two-Dimensional Fractional Volterra
Integro-Differential Equations

Abstract: Abstract In this paper, the collocation method is extended for solving two-dimensional fractional Volterra integro-differential equations (2D-FVIDEs). First, some theoretical results are presented to extend the collocation method to 2D-FVIDEs and to obtain corresponding linear algebraic system of equations. Then, it is proved the resulted linear system has a unique solution which shows the solution obtained from collocation method is unique. The convergence of the proposed method is also proved. Finally, some examples are given to illustrate the efficiency and accuracy of the proposed method.
PubDate: 2022-10-29

• Parametric Instability of an X-mode laser off a lower hybrid wave

Abstract: Abstract A high-frequency X-mode laser is susceptible to parametric decay into a lower hybrid wave and a sideband X-mode laser in magnetized plasma. The electron density perturbation associated with the lower hybrid wave couples with the oscillatory velocity due to the pump to produce a nonlinear current, driving the sideband. The pump and the sideband X-mode laser exert a low-frequency ponderomotive force on electrons driving the lower hybrid wave. For typical parameters, $$eA_{0} /m\omega c = 0.1,$$ $$\omega_{p} /\omega_{c} = 1,$$ $$m_{i} /m = 4000\,,$$ $$\omega_{pi} /\omega_{ci} = 25,$$ $$\omega_{0} /\omega_{ci} = 100$$ and $$k_{x} c/\omega = 0.1,$$ the growth rate increases linearly with $$\omega /\omega_{LH}$$ .
PubDate: 2022-10-28

• Effect of Fear, Treatment, and Hunting Cooperation on an
Eco-Epidemiological Model: Memory Effect in Terms of Fractional Derivative

Abstract: Abstract In this paper, we have studied a fractional-order eco-epidemiological model incorporating fear, treatment, and hunting cooperation effects to explore the memory effect in the ecological system through Caputo-type fractional-order derivative. We have studied the behavior of different equilibrium points with the memory effect. The proposed system undergoes through Hopf bifurcation with respect to the memory parameter as the bifurcation parameter. We perform numerical simulations for different values of the memory parameter and some of model parameters. In the numerical results, it appears that the system is exhibiting a stable behavior from a period or chaotic nature with the increase in the memory effect. The system also exhibits two transcritical bifurcations with respect to the growth rate of the prey. At low values of prey’s growth, all species go to extinction, at moderate values of prey’s growth, only preys (susceptible and infected) can survive, and at higher values of prey’s growth, all species survive simultaneously. The paper ended with some recommendations.
PubDate: 2022-10-26

• Biosynthesized Silver Nanoparticles Having High Redox Current Enhance
Anticancer Response for HepG2 Cells

Abstract: Abstract Silver nanoparticles (AgNPs) synthesized through the water extract of Trachyspermum ammi, Piper nigrum and Syzygium aromaticum had showed surface plasmon resonance in the range of 380 nm to 450 nm in UV–Vis spectra. Average size of these AgNPs was between 10 and 40 nm as observed in transmission electron microscopy image (TEM). High concentration of silver nitrate as a precursor showed an increase in the particle size, whereas the use of aqueous extract of Syzygium aromaticum exhibited high yield of AgNPs. Syzygium aromaticum synthesized AgNPs showed relatively increase in the oxidation peak current. The anticancer effect of these nanoparticles was investigated against HepG2 cells, and lowest IC50 value was observed in Syzygium aromaticum synthesized AgNPs as compared to the other two spices. Further, double staining by Hoechst 33,342/ PI dyes and DCFH-DA assay data unveiled that these nanoparticles induce apoptosis due to the generation of intracellular reactive oxygen species (ROS). The enhanced anticancer activities of Syzygium aromaticum synthesized AgNPs and corresponding increase in ROS. This may revealed that AgNPs with high redox current show the high anticancer properties.
PubDate: 2022-10-21

• The Effects of Pressure and Size Parameter on the Lattice Thermal
Conductivity in Multilayer Hexagonal Boron Nitride

Abstract: Abstract The shift in lattice thermal conductivity of multilayer hexagonal boron nitride is studied as a function of layer thickness, hydrostatic pressure, and temperature. A Morelli–Callaway model is used for pressures ranging from zero to 7 GPa and temperatures scale from 2 to 350 K. Hydrostatic pressure and size parameters such as the mean bond length, melting temperature, and bulk modulus affect the lattice thermal conductivity of bulk and multilayer hexagonal Boron Nitride. The peak value of lattice thermal conductivity for both bulk and multilayer is seen to fall when pressure is increased, and the decline in lattice thermal conductivity is greater as the number of layers decreases. The drop in thermal conductivity is due to a reduction in phonon movement in the system as the number of layers decreases. The Morelli–Callaway model based on Clapeyron–Murnaghan equations is an effective approach for determining the pressure impact of lattice thermal conductivity. The lattice thermal conductivity declined as pressure is reduced, and the mass density and bulk modulus decreased as the thickness of the thin layer increased, while compressibility, solid molar volume, and liquid molar volume rose. When the experimental data and theoretical calculations for bulk and multilayer h-BN were compared, the findings indicated good agreement. It's crucial to lower the heat conductivity of the materials that are useful for device applications.
PubDate: 2022-10-21

• Adsorptive Removal of Paclitaxel from Pharmaceutical Effluent Via
Fabricated Magnetic MWCNT and Graphene Oxide Nanocomposites

PubDate: 2022-10-19

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