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]
• 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

• 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

• γ-Ray Mass Attenuation Coefficients of Some Semiconductor Crystals at
Liquid Nitrogen Temperature

Abstract: Abstract In this study, the change according to the liquid nitrogen temperature (− 196 °C) of γ-ray mass attenuation coefficients ( $$\mu /\rho$$ ) for TlGaSe2, TlInGaSe2, Tl0.7In0.3Se2, Ga0.9In0.1Se, GaTe0.4Se0.6, GaTe0.8Se0.2, GaSe, GaSe:Sn, GaTe, and GaTe:Cd semiconductor crystals has been investigated by using an extremely narrow collimated-beam transmission method in the energy 59.54 keV. TlGaSe2, TlInGaSe2, Tl0.7In0.3Se2, Ga0.9In0.1Se, GaTe0.4Se0.6, GaTe0.8Se0.2, GaSe, GaSe:Sn, GaTe, and GaTe:Cd semiconductors were grown by the Bridgman-Stockbarger method in our current crystal growth laboratory. These crystals have been annealing at a temperature of 300 °C for 30 min. Then, these semiconductors were kept in liquid nitrogen for 3 min. $$\gamma$$ -ray mass attenuation coefficients of semiconductors were measured first at room temperature (25 °C) after annealing at (300 °C) and finally discarded into the liquid nitrogen (− 196 °C). $$\gamma$$ -rays of 241Am were detected by using a high-resolution Si(Li) detector and energy-dispersive X-ray fluorescence spectrometer (EDXRFS). The data were collected into 4096 channels of a multichannel analyzer and the spectra were collected for 1800s. Also, the experimental results have been compared with WinXCom and FFAST theoretical results for 25 °C.
PubDate: 2022-10-15

• Reconnaissance Hydrocarbon Prospecting of Afikpo, Oban Massif and Up-Dip
Niger Delta, Nigeria

Abstract: Abstract The purpose of this study is to identify areas with requisite sedimentary thickness and geothermal gradient capable of supporting the formation and accumulation of hydrocarbon fluids from organic rich source rocks. It also aims to delineate intra-sedimentary features that promote hydrocarbon migration and compartmentalization within reservoir rocks in Afikpo, Oban Massif and Niger Delta basins, southeastern Nigeria. Depths to the top and base of the magnetized crust were determined using statistical-spectral analysis of the aeromagnetic data contained in several square windows. The centroid method was applied and the results verified using forwarding modeling of the spectral peak. The results of spectral analysis show that the sedimentary thickness within the study area ranges from 1.35 to 3.84 km. Curie point depths (CPDs) obtained varies between 12.99 and 34.92 km. The maximum and minimum geothermal gradient values are 43.99° and 15.75°Ckm−1, respectively. These values show reasonable agreement with the results of earlier studies carried out in the region and nearby analogue basins. Some of the areas with shallow CPDs coincide with locations of thin sedimentary thickness, and deeper CPD regions correlate with areas of thick sedimentary cover. Good consistency was observed between the CPDs and geothermal gradient as areas of shallow CPDs tallied with zones of moderate and high temperature gradients. These results of geothermal gradients show remarkable agreement with wells data acquired within the Niger Delta Basin. The north–central, north–western and southeastern regions, which show sedimentary thickness of over 3 km in the presence of active intra-sedimentary structural elements as well as favorable temperature gradients, are recommended for further detailed petroleum system analysis.
PubDate: 2022-10-14

• Calcite Nanocrystal Production Using Locally Isolated Ureolytic Bacteria
and Assessing Their Resistance to Extreme Conditions

Abstract: Abstract Microbially induced calcium carbonate precipitation (MICP) is an abundant process in nature and involves the microorganism's activities. Therefore, our aim was to characterize the crystals precipitated by locally isolated urease-producing bacteria (Sporosarcina pasteurii N4, Lysinibacillus boronitolerance N6, Bacillus sp. N2, and Bacillus sp. N5) and to evaluate their resistance under extreme conditions. The Fourier transform infrared spectroscopy analysis confirmed the presence of calcium carbonate in the precipitates. The X-ray diffraction analysis demonstrated that calcite is the dominant polymorph produced using strains. The scanning electron microscope micrograph showed that precipitated calcium carbonate was in the shape of nanocrystal aggregates. The size of particles ranged between 20 and 50 nm. All survived strains were halotolerant and were able to grow in acidic and alkaline medium, but at an optimal pH level of 7. Bacterial growth obtained in the temperature range of 20–47 °C. Also, they showed 44–70% viability after 28-day desiccation stress using flow cytometry. These local bacteria can tolerate extreme conditions as well as production of calcium carbonate, and this suggests that four local strains are suitable candidates for the MICP applications. They can be a good alternative to conventional methods in the soil stabilization and other MICP-related applications.
PubDate: 2022-10-14

• Fundamental Changes in Theory of Duncan’s Model for Economic Design of
Control Charts in the Presence of Multiple Assignable Causes

Abstract: Abstract One of the most widely used tools for quality engineers in quickly detecting assignable causes and monitoring processes is control charts. Duncan (in J Am Stat Assoc 51(274):228–242, 1956), in order to improve product quality and reduce the economic costs of the quality cycle, presented the first economic design of the $$\bar{X}$$ control chart in the presence of multiple assignable causes. In his model and all the economic designs derived from it, it is assumed that after the occurrence of an assignable cause, no other assignable cause occurs until the correct alarm is issued. This assumption is unrealistic and impractical in production and service processes. Therefore, in this paper, we present a realistic and practical economic design in the presence of multiple assignable causes for the $$\bar{X}$$ control chart under the Weibull shock model in industry. The numerical results of our model show well that in the previous models, the average cost per unit time of the quality cycle is severely underestimated compared to the actual value. Therefore, it is suggested that in order to eliminate the shortcomings of the previous economic design in the presence of multiple assignable causes, in future research, they should be redesigned based on our proposed model.
PubDate: 2022-10-11

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