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

A problem that statisticians frequently face is the analysis of survival data obtained from a non-random sampling procedure. When each subject can be selected with a chance proportional to its measure, the bias imposed on the sample is called length bias. This paper uses empirical likelihood to construct confidence intervals for the regression coefficients using a Buckley–James type estimator when the underlying sample is length-biased. For this purpose, the empirical log-likelihood ratio is derived, and its asymptotic distribution is shown to be a standard chi-square. A simulation study is carried out to compare the confidence intervals based on the empirical likelihood and those based on the normal approximation. Following this, it is revealed that the empirical likelihood method improves the performance of the confidence intervals, specifically for small sample sizes. Finally, the methods are illustrated by modeling the regression parameter and estimating confidence intervals for a set of real data.

In this research, an environmentally friendly, effective method is documented for the synthesis of pyrido[2,3-d]pyrimidine and 1,2,4-triazolo[4,3-a]pyrimidine derivatives using an affordable and facile-prepared dicationic molten salt based on Tropine. The aforementioned pyrimidine derivatives have found remarkable pharmacological and therapeutic roles. under the influence of this catalyst formulated as [(Tropine)₂C₃H₅OH].2Cl, the products are obtained during 50 to 120 and 15 to 70 min for both reactions respectively, along with high yields from 90 to 98% which was measured through chromatography method, under solvent-free conditions or in EtOH as a green solvent. Also, the catalyst can be easily recovered and reused at least for three times.

Melissa officinalis L. (Lemon balm) is a medicinal plant rich in phenolic compounds, possessing numerous health benefits. To enhance the plant’s medicinal properties and antioxidant activity, this study investigated the effect of two species of Nostoc, as nitrogen-fixing cyanobacteria, on the growth and phytochemical responses of M. officinalis. Also, several metabolites content including total phenol, total flavonoid, and rosmarinic acid (RA) were assessed. Additionally, alterations in the expression of RA biosynthesis-related genes, such as Rosmarinic acid synthase (RAS), Phenylalanine ammonia lyase (PAL), and Tyrosine amino transferase (TAT), were examined quantitatively. Pot cultivation was performed in a randomized complete block design in a greenhouse, with the treated plants irrigated with cyanobacterial suspensions at 21-day intervals for 84 days. The results demonstrated that cyanobacterial-treated plants exhibited significant improvements in root and shoot length, fresh and dry weights, leaf number, and ramification compared to the control. Additionally, there was a significant increase in the levels of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and proline content in treated plants, indicating an induction of oxidative stress and potential activation of antioxidant pathways. Moreover, cyanobacterial treatment significantly increased the content of total phenols and total flavonoids, as well as rosmarinic acid (RA). Also, cyanobacterial-treated plants exhibited higher expression levels of PAL and RAS genes compared to the control, suggesting an enhancement in the production of RA. In conclusion, the application of cyanobacterial elicitors positively influenced the growth and phytochemical responses of M. officinalis, leading to higher RA content and increased levels of antioxidants. This research highlights the potential of cyanobacterial bioelicitors as a cost-effective and sustainable approach to improve the medicinal quality and antioxidant activity of medicinal plants.

Graphical Abstract

The effects of cyanobacteria, Nostoc spp., on total flavonoid and rosmarinic acid (RA) content, and expression levels of some RA biosynthesis-related genes in Melissa officinalis L., RAS: rosmarinic acid synthase, PAL: phenyl alanine ammonia lyase, TAT: tyrosine amino transferase

One of the key nuclear processes for heavy element creation in stellar and primordial nucleosyntheses is the ⁷Be (p,(gamma )) ⁸B radiative capture reaction. At very low energies, Effective Field Theory (EFT) provides a model-independent framework for describing physical observables. At the energy range studied, we calculated the S-factor for the E1 transition of the p + ⁷Be Radiative Capture Reaction (0–0.5 MeV). The leading M1 contribution is relevant at energies 600 keV around the ({1}^{+}) resonance, although it is negligible. In comparison to other experimental and theoretical investigations, the astrophysical S factor values extrapolated to zero energy are determined to be S₁₇ (0) = 20.90 eV.b and S₁₇*(0) = 21.13 eV.b for EFT and EFT*, respectively.

Environmental remediation through biological methods is one of the main concerns of nations today. Benzopyrene (BP) is the main component of polycyclic aromatic hydrocarbons, and has been frequently found in the air, surface water, soil, and sediments. BP is resistant to remediation because of their low water solubility. Laccases are one of the best materials that could be employed for degradation of BP. Bacterial laccases are a high thermostable enzyme that can endure a vast range of pH; however, due to their low redox potential and activity, they have not been studied thoroughly. In this work, site specific mutation at a site near the Cu1, which is the primary electron acceptor in laccase-catalyzed oxidation, was applied to a laccase from Bacillus subtilis to increase laccase activity. The mutated gene cotA laccase was cloned in pET22b(+) plasmid and transformed in expression host Escherichia coli BL21 (DE3). The recombinant protein was produced under optimum induction (37 °C), purified and then analyzed through SDS-PAGE method. Enzyme activity was analyzed by specific laccase substrate (ABTS). further analysis was done for enzyme properties in different temperature, pH, and salt concentration. The results showed that the recombinant enzyme had a higher activity than native enzyme in the same condition. Determining biological degradation characteristics of BP using the recombinant laccase indicated that the recombinant laccase was more stable in different conditions and had a high enzyme potential. The functionality assays of these enzymes imply that the mutant-type is more potent given its affinity with the benzo[a]pyrene as the corresponding ligand and ABTS oxidation as a substrate under the in-silico and in-vitro conditions respectively. Furthermore, the Km and Vmax of the purified enzymes were determined in line with their activities, so that the mutant-type revealed 54% decrease in Km and 5.5-fold increase in Kcat and an increase in Kcat/Km parameter. In addition, through HPLC technique, the comparison of BP degradation by the natural and mutant enzymes confirmed the superior capability of the mutant enzyme in BP removal.

COVID-19 (Coronavirus Disease-2019) is a highly contagious disease that began spreading towards the end of 2019 and quickly became a global pandemic. Despite extensive efforts taken by public health authorities and policymakers, the disease continues to persist globally. To overcome this scenario, we construct a spatio-temporal time-fractional COVID-19 model that incorporates non-linear density dependent diffusion coefficients as well as the Caputo time-fractional derivative, which captures the disease dynamics more relevantly. The main objective of this article is to explore the existence and uniqueness of global weak solutions for the proposed model. We first construct weak solutions as sequences in a finite-dimensional space. We then ensure the convergence of these sequences through energy estimates and compactness results, thereby establishing the existence of weak solutions for the proposed model using the Faedo–Galerkin method. We then prove the uniqueness of weak solutions. Finally, we study stability of the model in the Mittag–Leffler sense.

A nonlinear partial differential equation that accounts for shear strain waves in a long bone’s development plate is investigated. Lie group classification is performed on the underlying equation and it is found that the principal Lie algebra consists of a single time translation symmetry. The underlying analysis prompts that the principal algebra is extended by a single space translation and consequentially it is found the Lie algebra is two dimensional. A linear combination of the translation symmetries results in highly fourth-order nonlinear ordinary differential. Courtesy of an ansatz method this highly fourth-order nonlinear ordinary differential results in obtaining series of hyperbolic and trigonometric traveling wave solutions. Finally, we compute conservation laws courtesy of the invariance and multiplier technique. The findings can well mimic complex waves and their dealing dynamics in a long bone’s development.

(Sn⁺⁴ and Pb⁺⁴) mono-doping and (Sn⁺⁴-Pb⁺⁴), (Sn⁺⁴-S^-2), and (Pb⁺⁴-S^-2) co-doping were used to investigate the performance of the water splitting activity of the (111) TiO₂ monolayer by performing periodic density functional theory (DFT) calculations. The pure (111) monolayer with a large bandgap energy (3.9 eV) limits the absorption of sunlight. However, the pure structure has appropriate conduction band (CB) and valence band (VB) energy edges, which, respectively, are above the reduction potential of the H⁺/H₂ and below the oxidation potential of H₂O/O₂ half-reactions. Upon Sn⁺⁴ and Pb⁺⁴ mono-doping and (Sn⁺⁴-Pb⁺⁴), (Sn⁺⁴-S^-2), and (Pb⁺⁴-S^-2) co-doping, the band gap energy of the (111) TiO₂ monolayer becomes smaller than that of the corresponding pure monolayer, which increases the photocatalytic efficiency. Among the considered monolayers in this work, the Sn⁺⁴ mono-doped as well as the (Sn⁺⁴-S^-2) co-doped (111) TiO₂ monolayers, which have appropriate CB energy potential for proton reduction, are the most desirable photocatalysts for hydrogen production. It is noted that all structures particularly the Pb⁺⁴ mono-doped, (Sn⁺⁴-Pb+⁴) and (Pb⁺⁴-S^-2) co-doped (111) TiO₂ monolayers with appropriate VB edges and narrow band gap energies are good candidates for O₂ evolution.

Several mechanisms that plants utilize to cope with the effects of drought stress are mediated by ethylene. However, plants utilize several mechanisms to cope with the adverse effects of drought stress through ethylene. As the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase can break ACC, the precursor of ethylene synthesis, the ACC deaminase-producing bacteria can be used to improve plant tolerance to drought stress. Silicon (Si) has beneficial effects on not only plant growth but also on environmental stresses such as drought stress. A field experiment was carried out to assess the effect of drought stress tolerant ACC deaminase-producing bacteria with and without the application of Si on the growth and yield of wheat under drought stress conditions. A novel bacteria strain, registered in the GenBank of BankIt with the Accession Number KT59926, Bacillus simplex UT1, was applied in this experiment. The main plots were three levels of irrigation (I) consisted of 7I level including all seven irrigation times as irrigation applied at stages of cultivation, seed germination, tillering, initial and mid-stem elongation, pre-flowering and grain-filling, five irrigation stages (5I), and three irrigation stages (3I). Sub-plots were randomly divided into four levels of treatments, including control treatment (no inoculation of bacteria, no Si application, and recommended nitrogen, phosphorus, potassium, and zinc fertilizers), the treatment of the application of B. simplex UT1, the treatment of the Si application as potassium silicate at the rate of 10 mg plant⁻¹, and the treatment of the combined application of B. simplex UT1 and silicon. The experiment was conducted as a randomized complete block design with four replicates (12 × 4 = 48 plots). Results indicated that the application of deficit irrigation increased the ethylene concentration of stems in all treatments, while the combined application of B. simplex UT1 and Si declined ethylene concentration. Irrigation saving (5I) decreased yield traits: grain yield (24.2%) and biological yield (26.2%), compared to the control irrigation level (7I). Combined application of B. simplex UT1 and Si decreased grain and biological yield by 12.4% and 11.5%, respectively. The application of the same treatment under the 3I level resulted in a greater increase in some yield traits including grain yield (16.1%) and biological yield (15.5%) compared to the control treatment. Significant differences in chlorophyll a, chlorophyll b, and solute conductance as affected by the combined inoculation of bacteria strain and application of Si were observed. Therefore, the combined applications of B. simplex UT1 and Si were effective in the alleviation of drought stress and enhancement of wheat production.