Kuwait Journal of Science最新文献

A useful extension of the Laplacian matrix is proposed here and the corresponding modification of the Laplacian energy ($LE$) is presented. The neighbourhood degree sum-based Laplacian energy ($L_{N}E$) is produced by means of the eigenvalues of the newly introduced neighbourhood degree sum-based Laplacian matrix ($L_N$). We investigate the mathematical properties of $L_{N}E$ by comparing it with the Laplacian energy. The role of $L_{N}E$ in structure–property modelling of molecules is demonstrated by statistical approach. The formulation of $L_{N}E$ is not ad hoc; rather, its chemical significance exerts that it outperforms $LE$ in modelling physiochemical behaviours of molecules. Mathematical properties of $L_N$ are also revealed by finding crucial bounds of its eigenvalues with characterizing extremal graphs.

The precipitation over the Indonesian Maritime Continent (IMC) is one of the most challenging atmospheric parameters to predict accurately. The Weather Research Forecasting (WRF) model used in this study produces overestimated predictions of precipitation intensity compared to satellite data. Therefore, it is necessary to modify the model output to minimize the bias between predictions and satellite observations. The modification includes adjusting the dynamic model parameters and settings to better reflect atmospheric conditions in the IMC region, applying bias correction techniques through a linear scaling method, aligning the monthly average of the model's output with observational data, and conducting statistical analysis in several areas within the IMC. This procedure has significantly reduced the biases and is considered acceptable for each satellite area. Based on the results of the statistical analysis and by applying the precipitation threshold criteria, the accuracy of the predictions in each observation area is quite good, ranging from 0.59 to 1.0. Precipitation with a threshold of 50 mm/day or higher exhibits good accuracy, with a minimum value of 0.59 for RI and a maximum value of 0.97 for RIII and RV. On the other hand, precipitation with a threshold of 20 mm/day or higher demonstrates very good accuracy, with values of 0.97 for RI and 1.00 for RIII to RVI.

This study utilizes a hydrothermal-solvothermal method to facilitate the fabrication of organobentonite (OB) by intercalating the surfactant octadecylamine (ODA) using several solvents (water (OB-Aq), ethanol (OB–Et), and mix 50% water/ethanol (OB-Aq/Et)). The physicochemical features of the materials were investigated using X-ray diffraction, Fourier transform infrared, scanning electron microscopy, Brunauer-Emmett-Teller surface analyzer, and thermogravimetry differential thermal analysis characterization. The study of structural properties found that surfactant intercalation transformed the basal spacing. This was shown by a lower x-ray diffraction value of 2θ at <6° and the presence of peeled-off layers in the scanning electron microscope image. The thermogravimetry analysis and regeneration adsorption evaluated the structural stability of OB, demonstrating its capacity to withstand temperatures up to 300 °C and undergo three cycles of adsorption. In addition, the adsorption processes on direct yellow are mainly characterized by the pseudo-first-order kinetic and Langmuir isotherm models. The interaction between alumina-silica bentonite and ODA chains in this investigation influenced the adsorption mechanism. The adsorption system is influenced by pH, temperature, and ion competition, which can induce the disintegration of the direct yellow structure from the surfaces of the adsorbent. The mesoporous structures obtained have the highest Langmuir chemisorption capacities for OB-Aq, OB-Et, and OB-Aq/Et, with values of 270.27 mg/g, 108.696 mg/g, and 2000 mg/g, respectively. This work suggests using an efficient method to fabricate OB for anionic dyes removal, specifically direct yellow.

Contamination in domestic and drinking water during the conveyance process is one of the biggest health risks of all time. This is a very common hazard that is expected in the areas where water, sewer, and drainage pipes are laid in trenches near each other. The extent of the contamination spread in the case of intrusion through a pipe leak for water distribution networks (WDNs) laid on sloping terrain is not known. This article deals with the simulation and hydraulic analysis of organic contaminant intrusion in WDNs with significant consideration of the slope of the laid pipes. The source of organic contamination is considered to be the nearby leaking sewer water. The effects of sloping terrain on contaminant spread in the pipe network are studied in detail by injecting contaminant concentrations at eight different critical locations in the network. The results of contamination spread after a particular time at all nodes are compiled, and by using statistical techniques, a relation between the contaminant spread and pipe slope is proposed. The presented model is validated by comparing the actual values of the contaminant in water samples obtained at the site with the calculated ones, and it shows that the values deviate within the range of ±2% only, which is considered a good match. The research proves to be beneficial for the management of water distribution through pipe networks against contaminants to maintaining water quality and public health.

The need to increase thermal power stability and energy conservation have spurred the interest in various renewable energies. A diverse range of fabrication techniques and architectures have been developed to meet the global energy demand. Perovskite solar power technologies are the next emerging generation of photovoltaic thermal power systems for an enhanced and stable power supply. Thus, this project examines the thin radiation thermal stability of combined magneto-hybrid silicon oxide (SiO₂) and aluminum oxide (Al₂O₃) nanoparticles in exothermic propylene glycol (C₃H₈O₂)-Williamson fluid for perovskite thermal cells improvement. Without particles agglomeration, the fluid flow is influenced by lower wall velocity, Joule heating and Williamson shear stress in a bounded domain. An invariant coupled differential model is obtained through the similarity transformation of the governing model. The solutions to the invariant model is provided using semi-discretized finite difference method. The outcomes revealed that nanoparticles thermal propagation for perovskite power generation is strengthened with rising Brinkman number, radiation, and Frank-Kamenetskii terms. Also, criticality is raised at the unstable thermal region but damped at the stable thermal regime.

Herein, we report the influence of Ni at different concentrations on manganese oxide catalyst support (Ni/α-MnO₂) prepared by the combined wet-impregnation and chemical reduction methods. A correlated dependence of Ni concentration was observed on the structural, surface, and morphological properties of the catalyst. The catalytic activity of Ni/α-MnO₂ was evaluated for benzene hydrogenation to cyclohexane. Ni/α-MnO₂ shows superior catalytic activity, and benzene conversion efficiency achieves 96.1%, which is 2.4 times greater compared to α-MnO₂. Interestingly, high Ni species concentration on α-MnO₂ results in an increased benzene conversion percentage. The result is synergistically attributed to the highly dispersed Ni species on the surface of α-MnO₂, increased acidity, and the improved pore diameter of the Ni/α-MnO₂. This work provides a facile and convenient method to develop α-MnO₂ doped by Ni at various concentrations for enhanced catalytic performance as an alternative strategy to cope with the presence of aromatic compounds in fossil fuels.

Coconut shell waste can generate environmental problems if left without treatment, as it contains lignin, cellulose, and hemicellulose compounds, which pyrolyze to produce liquid smoke, charcoal, and tar. This study aims to prepare and characterize liquid smoke using several parameters, including the chemical content preserving tofu and the hedonic test of consumer preferences. The dried coconut shell (3000 g) was pyrolyzed at 300 °C for 5 h. Liquid smoke (grade 3) was purified by distillation (grade 2) and filtered with activated charcoal to produce grade 1 liquid smoke. The liquid smoke properties were characterized as yield, pH, phenol, and moisture, while the chemical components were identified by gas chromatography-mass spectroscopy (GC-MS). For the commercial and coconut shell liquid smoke (grade 1) used in this study, the application was aimed at preserving the tofu for three days. Panelists observed the aroma, the texture, and the appearance compared to the control. Ten panelists performed the hedonic test of fried preserved tofu. The organoleptic aspects included taste, texture, aroma, and color. The liquid smoke obtained from coconut shell pyrolysis was red-brown, with a yield of 52.75%, pH 0.5 (grade 3), pH 1.7 (grade 2), and pH 2.3, with a total phenol of 2.479 (grade 1). The GC-MS results exhibited three essential chemical compounds, namely phenol, methoxy phenol, and hydroxyphenyl phosphonic acid, influencing the preservation. The liquid smoke solution extended the shelf life of tofu, especially at a concentration of 1.5 (% v/v), so the water content decreased. The average panelist responded “good” on the hedonic test on all of the tofu treatments compared to the control.

The concept of Roman domination has been a subject of intrigue for more than two decades, with the fundamental Roman domination problem standing out as one of the most significant challenges in this field. This article studies a practically motivated generalization of this problem, known as the $k$-strong Roman domination. In this problem variant, defenders within a network are tasked with safeguarding any $k$ vertices simultaneously, under multiple attacks. The aim is to find a feasible mapping that assigns a (integer) weight to each vertex of the input graph with a minimum sum of weights across all vertices. A function is considered feasible if any non-defended vertex, i.e. one labeled by zero, is protected by at least one of its neighboring vertices labeled by at least two. Furthermore, each defender ensures the safety of a non-defended vertex by imparting a value of one to it while retaining a one for themselves. To the best of our knowledge, this paper represents the first theoretical study on this problem. The study presents results for general graphs, establishes connections between the problem at hand and other domination problems, and provides exact values and bounds for specific graph classes, including complete graphs, paths, cycles, complete bipartite graphs, grids, and a few selected classes of convex polytopes. Additionally, an attainable lower bound for general cubic graphs is provided.

Current breast cancer therapeutics are associated with short-term efficacy, increased drug resistance, and severe adverse reactions, thus demanding the development of new therapeutic approaches. This present study aimed to explore the cytotoxic activity of Morchella extracts in the context of the MCF-7 cell line (breast cancer) and ultra-performance liquid chromatography mass spectroscopy (UPLC-MS) analysis. The cytotoxic activity of the Morchella conica, Morchella delicosa, and Morchella escuelnta extracts was examined against the breast cancer cell line (MCF-7), using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay (MTT assay). The Morchella extracts were screened for the presence of compounds using ultra-performance liquid chromatography mass spectroscopy (UPLC-MS/MS) based analysis. All the Morchella extracts actively restricted the viability and proliferation of breast cancer cells in a dose-dependent manner, with half maximal inhibitory concentration (IC50) values ranging from 0.017 to 0.68 mg/ml. The main compounds identified in Morchella include alkaloid, sterol, flavonoid, terpenoid, fatty acid, peptide, glutamic acid, amino acid, coumarin, and cyclopyrrolone. In conclusion, Morchella extracts exhibited cytotoxic effects against breast cancer cell lines and decreased the viability of MCF-7 cell line. The Morchella compounds might be the main components contributing to the inhibition of breast cancer cells. The findings of this research offer an innovative framework for advanced investigations for the development of cancer therapeutics from this fungus.

In this work, the stems, leaves, and flowers of Ruta chalepensis L., R. graveolens L., and R. montana L. harvested in Morocco were subject to a comparative study to determine the phytochemical composition, antioxidant capacities, and the content of total phenols and flavonoids. For this purpose, 45 crude extracts (CEs) were prepared using different solvents, including water, ethyl acetate, methanol, ethanol, and hexane. Upon undergoing secondary metabolites screening, it was discovered that the different parts of three Ruta species contain a high level of secondary metabolites such as alkaloids, catechic tannins, flavonoids, coumarins, sterols, and triterpenes. This was confirmed by the results of the quantitative analysis, which proved that the three Ruta species contain a significant amount of total phenolic compounds, ranging from 27.05 to 213.42 mg GAE/g CE. With regard to antioxidant capacities, antiradical power (ARP) results prove that the majority of CEs have great ARP (were within the range of 0.42–1.99) compared to the BHT (butylated hydroxytoluene) standard (0.33 APR). In addition, the results of total antioxidant capacity (TAC) analysis of Ruta CEs showed good TAC (varies between 37.67 and 396.80 mg AAE/g CE).