Search Results (143)

Due to the environmental concerns surrounding widely used antimicrobial agents, the use of nanotechnology to suppress crop diseases has attracted increasing attention in the agricultural field. This paper investigated the inhibitory effects of manganese-based nanomaterials (NMs) on rice leaf blight. In vitro experiments showed that manganese oxide (MnO₂) NMs and manganese tetroxide (Mn₃O₄) NMs directly inhibited Xanthomonas oryzae (Xoo) with a maximum OD value of 0.177, which was 11.5% lower than the control. In vivo experiments demonstrated that spraying MnO₂ NMs and Mn₃O₄ NMs reduced the diseased leaf length to 22–28% and 25–26%, respectively. This is due to Mn-based NMs inducing enhanced plant resistance by increasing the activity of phenylalanine ammonia–lyase in rice leaves by 36–61%. Single particle inductively coupled plasma mass spectrometry showed that Mn₃O₄ NMs are more frequently retained as NMs in rice than MnO₂ NMs, resulting in enhanced antimicrobial effects. Mn-based NMs exhibit strong antimicrobial activity and hold significant promise as alternatives for plant protection and agricultural applications; however, careful consideration must be given to their concentrations and application methods. Full article

An isocratic reverse-phase high-performance liquid chromatography (RP-HPLC) method, coupled with photodiode array detection (PDA), was developed for the identification and characterization of stress degradation products and an unknown process-related impurity of rivaroxaban in bulk drug form. Rivaroxaban, a selective and direct Factor Xa inhibitor, underwent forced degradation under hydrolytic (acidic, alkaline, and neutral), photolytic, thermal, and oxidative stress conditions, following the ICH’s guidelines. The drug displayed significant susceptibility to acid, base, and oxidative environments leading to the formation of eleven degradation products. All degradation products, along with process impurities and Rivaroxaban, were effectively separated using a (4.6 × 250 mm, 5 µm) C18 Thermo ODS Hypersil column at ambient temperature. The mobile phase composed of acetonitrile and monobasic potassium phosphate (pH 2.9) in a 30:70 (v/v) ratio, with a flow rate of 1.0 mL/min, and detection was carried out at 249 nm. The LC-PDA method was validated in accordance with the ICH’s guidelines and USP38-NF33, demonstrating specificity, linearity, accuracy, precision, and robustness. Recovery studies showed results within the range of 98.6–103.4%, with a % RSD LT 2%. The limits of detection (LOD) and quantitation (LOQ) for rivaroxaban were determined to be 0.30 ppm and 1.0 ppm, respectively. Stress studies confirmed that the degradation products did not interfere with rivaroxaban detection, establishing the method as stability-indicating. Specific impurities were identified, including impurity G at 2.79 min, impurity D at 3.50 min, impurity H at 5.32 min, impurity C at 6.14 min, impurity E at 8.36 min, impurity A at 9.03 min, and impurity F at 9.49 min. Additionally, several unknown impurities were observed at 3.20, 4.00, 4.59, and 4.77 min. Statistical evaluation confirmed the method’s reliability, making it suitable for routine analysis, quality control of raw materials, formulations of varying strengths, dissolution studies, and bioequivalence assessments of rivaroxaban formulations. Full article

The sunny–shady slope effect (SSSE) disrupts the thermal balance of permafrost subgrades, resulting in asymmetric thaw plates that lead to structural deformations such as longitudinal cracking and slope instability along the Qinghai–Tibet Highway (QTH). This study proposes three morphological indicators—road shoulder thawing depth difference (RSTDD), offset distance (OD), and active layer thickness difference (ALTD)—to quantitatively characterize the asymmetry of thaw plates. Through integrating remote sensing data and large-scale geological survey results with an earth–atmosphere coupled numerical model and a random forest (RF) prediction framework, we assessed the spatial distribution of thaw asymmetry along the permafrost section of the QTH. The results indicate the following: (1) The ALTD values are overall very small and almost unaffected by the SSSE. The RSTDD increases with mean annual ground temperature (MAGT) before stabilizing, while the OD shows no significant response to the MAGT. The RSTDD and OD ranges are 0–3.38 m and 0–8.65 m, respectively, and they are greatly affected by the SSSE. (2) The RSTDD and OD show obvious spatial differences in different geographical regions of the QTH. An RSTDD greater than 2 m is concentrated in the Xidatan Faulted Basin and Chumar River High Plain. An OD greater than 3 m is mainly distributed from the Chumar River High Plain to the Tongtian River Basin. (4) The RSTDD and OD are most affected by subgrade orientation with importance values of 49.84% and 51.80%, respectively. The importance of the effect of mean average ground temperature (MAGT) on the active layer thickness is 80.58%. Full article

This study systematically analyzed the color characteristics, microscopic inclusions (including fluid and mineral inclusions), spectral properties, and chemical composition of emerald samples from Kafubu, Zambia using infrared spectroscopy, UV–visible spectroscopy, Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The results were then compared with research data on emeralds from Afghanistan, Brazil, China, Colombia, Ethiopia, Madagascar, Russia, and the United States. The result establishes a global classification framework for emerald origins based on chromophores (Cr, V, Fe), categorizing deposits into two distinct groups: low-Fe regions and high-Fe regions. For high-Fe type IA emeralds, particularly those from Zambia and Madagascar exhibiting exceptionally similar Fe and Mg concentrations, a multi-element discrimination approach was developed. Using microscopic infrared testing to magnify and analyze the characteristic peaks related to OD in the range of 2550–2800 cm⁻¹, it can be classified as HDO-dominant, and the high alkali metal element content in Zambian emeralds can be reflected by the absence of the HDO vOD absorption peak at 2685 cm⁻¹. A further in-depth analysis of the trace elements in Zambian emeralds can provide a basis for inferring the possible rich ore geology for subsequent mining and provide more effective reference data for the identification of the origin of emeralds. Full article

Modeling cascading failure in an urban rail transit network (URTN) is essential for evaluating the impact of interruptions and network resilience. Here, a weighted coupled map lattice (CML) model is proposed. This model combines structural network coupling and passenger flow coupling to analyze the cascading failure process triggered by a station failure. Four network performance indicators are developed: network efficiency and subgraph connectivity from the network structure perspective, and OD connectivity and the reciprocal of average transfers from the network service perspective. The resilience of a URTN is measured based on the network performance indicators during station failures. Application of the model to the Wuhan URTN showed that station failure with high numbers of boarding and alighting passengers caused the highest decline in network resilience. The network’s structural resilience was stronger than its service resilience. The relationship between the percentage of failed stations and network performance indicated a significant threshold effect at a 5% failure percentage. Specifically, network performance decreased rapidly when the percentage of failed stations was below 5% and more gradually when it exceeded this threshold. Moreover, network performance exhibited high sensitivity to increases in external perturbation intensity when the failure station percentage was below 5%, but this sensitivity diminished significantly once the percentage surpassed 5%. Full article

The ability of a cell to keep its volume constant irrespective of intra- and extracellular conditions is essential for cellular homeostasis and survival. The purpose of this study is to elaborate a theoretical model of cell volume homeostasis and to apply it to a simulation of human aqueous humor (AH) production. The model assumes a cell with a spherical shape and only radial deformation satisfying the property that the cell volume in rest conditions equals that of the cell couplets constituting the ciliary epithelium of the human eye. The cytoplasm is described as a homogeneous mixture containing fluid, ions, and neutral solutes whose evolution is determined by net production mechanisms occurring in the intracellular volume and by water and solute exchange across the membrane. Averaging the balance equations over the cell volume leads to a coupled system of nonlinear ordinary differential equations (ODEs) which are solved using the $\theta$-method and the Matlab function ode15s. Simulation tests are conducted to characterize the set of parameters corresponding to baseline conditions in AH production. The model is subsequently used to investigate the relative importance of (a) impermeant charged proteins; (b) sodium–potassium (Na+/K+) pumps; (c) carbonic anhydrase (CA) in the AH production process; and (d) intraocular pressure. Results suggest that (a) and (b) play a role; (c) lacks significant weight, at least for low carbon dioxide values; and (d) plays a role for the elevated values of intraocular pressure. Model results describe a higher impact from charged proteins and Na+/K+ ATPase than CA on AH production and cellular volume. The computational virtual laboratory provides a method to further test in vivo experiments and machine learning-based data analysis toward the prevention and cure of ocular diseases such as glaucoma. Full article

In engineering, physics, and other fields, implicit ordinary differential equations are essential to simulate complex systems. However, because of their intrinsic nonlinearity and difficulty separating higher-order derivatives, implicit ordinary differential equations pose substantial challenges. When applied to these types of equations, traditional numerical methods frequently have problems with convergence or require a significant amount of computing power. In this work, we present the multi-stage differential transform method, a novel semi-analytical approach for effectively solving first- and second-order implicit ordinary differential systems, in conjunction with Adomian polynomials. The main contribution of this method is that it simplifies the solution procedure and lowers processing costs by enabling the differential transform method to be applied directly to implicit systems without transforming them into explicit or quasi-linear forms. We obtain straightforward and effective algorithms that build solutions incrementally utilizing the characteristics of Adomian polynomials, providing benefits in theory and practice. By solving several implicit ODE systems that are difficult for traditional software programs such as Maple 2024, Mathematica 14, or Matlab 24.1, we validate our approach. The multi-stage differential transform method’s contribution includes expanded convergence intervals for numerical results, more accurate approximate solutions for wider domains, and the efficient calculation of exact solutions as a convergent power series. Because of its ease of implementation in educational computational tools and substantial advantages in terms of simplicity and efficiency, our method is suitable for researchers and practitioners working with complex implicit differential equations. Full article

We derive a one-dimensional macroscopic model for biofilm formation in a porous medium reactor to investigate the role of longitudinal diffusion of substrate and suspended bacteria on reactor performance. By comparing an existing base model—one without longitudinal diffusion, which was the point of departure for our work, to the new model—we noticed significant changes in system dynamics. Our results suggest that neglecting it can lead to underestimation of quenching length and biofilm accumulation downstream, even in the advection-dominated regime. The effects of attachment and detachment of suspended bacteria on biofilm formation and substrate degradation were also examined. In the one-dimensional model, it was found that attachment has a stronger influence on substrate depletion, which becomes more pronounced as diffusion in the pore space increases. Full article

We synthesized n-type polymers poly{[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} [P(NDI2OD-T2)] and poly{[N,N′-bis(3-(4-cardanol)propyl)-naphthalene-1,4,5,8-tetracarboxylic diimide]-alt-[5,5′-bis(2-thienyl)-2,2′-bithiophene]} [P(NDICL-T2)] with cardanol-based side chains via Stille coupling to enhance electron mobility. Replacing the 2-octyldodecyl side chain with cardanol in P(NDICL-T2) improved electron mobility due to increased chain flexibility and ordered packing. Lower glass transition temperature (t_g), red-shifted UV-vis absorption, results from crystalline structure analysis, indicating tighter lamellar spacing and enhanced molecular ordering, and smoother surface morphology confirmed the enhanced intermolecular interactions and uniform film formation. Full article

As a novel industrial space to cope with global competition, industrial parks have gradually become important growth poles to promote regional development and provide a large number of employment opportunities. This study utilizes mobile phone signaling data to identify the commuting origins and destinations (OD) of different industrial parks in Nanjing while comparing the distribution of the working population, residential population, and commuting patterns across varying types and levels of industrial parks. The level of coordination of the employment–residential system in each park is quantified by calculating the resident commuting index (HSC_i), employee commuting index (WSC_i), and their coupling coordination degree. Additionally, geographic detectors are employed to identify the influencing factors and interaction effects that impact the employment–residential balance in industrial parks. Results show that industrial parks located in the central urban area attract more residential and working populations. The commuting volume of national and municipal as well as high-tech industrial parks is higher than other types of industrial parks. Most industrial parks experience more inward than outward commuting, and there is an uneven distribution of commuting flows, resulting in a network-like pattern of “central dense, peripheral sparse”. Various industrial parks exhibit a highly coupled job–housing system, and those with high HSC_i tend to have high WSC_i as well. The coupling coordination of industrial parks ranged from 0.16 to 0.93, with 13 being primary coordination or above and 3 being disordered. Industrial parks are classified into three types: employment-oriented, residential-oriented, and employment–residential balanced, with the residential-oriented type being predominant. The density of public transportation stops, park area, and land use mix are the primary factors affecting the employment–residential balance. Industrial parks with larger scale, better land allocation, and higher service facility levels are more likely to achieve coordination in the employment–residential system. Our work utilizes mobile signaling data to characterize the commuting patterns of industrial parks, providing insights for industrial park planning and promoting the integration of industry and city. Full article

This paper employs an integral reinforcement learning (IRL) method to investigate the optimal tracking control problem (OTCP) for nonlinear nonzero-sum (NZS) differential game systems with unknown drift dynamics. Unlike existing methods, which can only bound the tracking error, the proposed approach ensures that the tracking error asymptotically converges to zero. This study begins by constructing an augmented system using the tracking error and reference signal, transforming the original OTCP into solving the coupled Hamilton–Jacobi (HJ) equation of the augmented system. Because the HJ equation contains unknown drift dynamics and cannot be directly solved, the IRL method is utilized to convert the HJ equation into an equivalent equation without unknown drift dynamics. To solve this equation, a critic neural network (NN) is employed to approximate the complex value function based on the tracking error and reference information data. For the unknown NN weights, the least squares (LS) method is used to design an estimation law, and the convergence of the weight estimation error is subsequently proven. The approximate solution of optimal control converges to the Nash equilibrium, and the tracking error asymptotically converges to zero in the closed system. Finally, we validate the effectiveness of the proposed method in this paper based on MATLAB using the ode45 method and least squares method to execute Algorithm 2. Full article

This manuscript investigates the existence, uniqueness, and different forms of Ulam stability for a system of three coupled differential equations involving the Riemann–Liouville (RL) fractional operator. The Leray–Schauder alternative is employed to confirm the existence of solutions, while the Banach contraction principle is used to establish their uniqueness. Stability conditions are derived utilizing classical nonlinear functional analysis techniques. Theoretical findings are illustrated with an example. The proposed system generalizes third-order ordinary differential equations (ODEs) with different boundary conditions (BCs). Full article

This paper investigates the long-time behavior of fractional-order complex memristive neural networks in order to analyze the synchronization of both anatomical and functional brain networks, for predicting therapy response, and ensuring safe diagnostic and treatments of neurological disorder (such as epilepsy, Alzheimer’s disease, or Parkinson’s disease). A new mathematical brain connectivity model, taking into account the memory characteristics of neurons and their past history, the heterogeneity of brain tissue, and the local anisotropy of cell diffusion, is proposed. This developed model, which depends on topology, interactions, and local dynamics, is a set of coupled nonlinear Caputo fractional reaction–diffusion equations, in the shape of a fractional-order ODE coupled with a set of time fractional-order PDEs, interacting via an asymmetric complex network. In order to introduce into the model the connection structure between neurons (or brain regions), the graph theory, in which the discrete Laplacian matrix of the communication graph plays a fundamental role, is considered. The existence of an absorbing set in state spaces for system is discussed, and then the dissipative dynamics result, with absorbing sets, is proved. Finally, some Mittag–Leffler synchronization results are established for this complex memristive neural network under certain threshold values of coupling forces, memristive weight coefficients, and diffusion coefficients. Full article

With the increase in the number of distributed energy resources (DERs) and electric vehicles (EVs), it is particularly important to solve the problem of EV charging station siting and capacity determination under the distribution network considering a large proportion of DERs. This paper proposes a bi-level planning model for EV charging stations that takes into account the characteristics of the spatial–temporal distribution of charging loads under an uncertain environment. First, the Origin–Destination (OD) matrix analysis method and the real-time Dijkstra dynamic path search algorithm are introduced and combined with the Larin Hypercube Sampling (LHS) method to establish the EV charging load prediction model considering the spatial and temporal distribution characteristics. Second, the upper objective function with the objective of minimizing the cost of EV charging station planning and user charging behavior is constructed, while the lower objective function with the objective of minimizing the cost of distribution network operation and carbon emission cost considering the uncertainty of wind power and photovoltaics is constructed. The constraints of the lower-layer objective function are transformed into the upper-layer objective function through Karush–Kuhn–Tucker (KKT) conditions, the optimal location and capacity of charging stations are finally determined, and the model of EV charging station siting and capacity determination is established. Finally, the validity of the model was verified by planning the coupled IEEE 33-node distribution network with the traffic road map of a city in southeastern South Dakota, USA. Full article

The yeast Yarrowia lipolytica degrades petroleum compounds, including alkanes, via the monoterminal oxidation pathway, the hydrophobic carbon substrate assimilation is mediated by biosurfactants, and extracellular amphiphilic molecules are produced by the yeast cell. This study focuses on the ability of the strain Y. lipolytica CMGB32 to degrade n-hexadecane by producing biosurfactants with high potential for bioremediation. The hydrocarbon-degrading potential of the yeast strain was observed via a 2,6-dichlorophenolindophenol (DCPIP) test in Bushnell–Hass medium with 1% n-hexadecane, and cell hydrophobicity was expressed as microbial adhesion to hydrocarbons (MATH). Biosurfactant production on yeast peptone (YP) with 1% n-hexadecane was estimated after 72 h using the emulsification index (E₂₄%) against toluene. Crude biosurfactant (cell-free broth) stability tests were performed at different temperatures (4 °C, 70 °C) and NaCl concentrations (2–10%). The effects of a biosurfactant on synthetic wastewater remediation comprised the growth curves (OD measurements) of natural heavy metal degrader Rhodotorula mucilaginosa, determination of nutrients (spectrophotometrically), physico-chemical parameters, and removal capacity of lead and cadmium ions (via inductively coupled plasma mass spectrometry—ICP-MS). The antimicrobial and anti-adherence activities of 20 mg/mL and 40 mg/mL of the biosurfactant against pathogenic Candida krusei strains involved growth observations and the crystal violet microtiter method. The DCPIP decolorization occurred after six days, corresponding to the maximum growth phase of the Y. lipolytica culture. After 72 h, the cells presented high hydrophobicity (82.61% MATH) and stable biosurfactant production (E₂₄% 47%). The crude biosurfactant (5%) increased the growth of R. mucilaginosa strains cultivated on synthetic wastewater cultures contaminated with Pb²⁺ and Cd²⁺, increased the conductivity and COD (86%) of the samples, and determined Pb²⁺ (66%) and Cd²⁺ (42%) ions reduction. The concentrated biosurfactant inhibited C. krusei growth (70%) and biofilm adherence. In conclusion, Y. lipolytica CMGB32 shows important potential for development of biosurfactant-based technologies for the remediation of heavy-metal- and emerging pathogen-contaminated wastewaters. Full article