Pacific Science Review A: Natural Science and Engineering最新文献

Volatile oils of Mentha piperita L (M. piperita) contain various chemical constituents. The aim of this work is to isolate essential oil from leaves of M. piperita, which is native to the Sultanate of Oman, by steam distillation and to analyse chemical constituents by gas chromatography–mass spectroscopy (GC–MS). Fourteen main chemical compounds, representing 91.11% of the leaf oils, were identified in essential oils as carvone (34.94%), pulegone (14.89%), methyl petroselinate (15.51%), d-limonene (11.20%), ρ-cineole (5.70%), methyl isoheptadecanoate (2.35%), 1-tridecene (2.21%), methylene-6,10,10-trimethylbicyclo (7.2.0), undec-5-ene (0.91%) and isopulegone (0.89%). Some minor chemical compounds were also obtained (verbenone (0.72%), β-myrcene (0.57%), β.-pinene (0.73%), sabinene (0.49%) and α-pinene (0.49%)). The extracted methanol extract of M. piperita and its fractions of hexane, chloroform, ethyl acetate, and butanol extracts as well as essential oil were tested for antimicrobial activity via disc diffusion. The crude extracts and essential oils exhibited moderate antibacterial activity against the tested bacteria (e.g., Gram positive Staphylococcus aureus (S. aureus), Gram negative Escherichia coli (E. coli) and Xanthomonas campestris (X. campestris)) within a range of 0–14%. Our findings demonstrate that leaf extracts and essential oils of M. piperita exhibit excellent antimicrobial activity and thus have strong potential as a source of natural antibiotics.

Ammi majus (A. majus) is an important medicinal plant traditionally used in Oman for the treatment of mouth ulcers. The objective of this study was to determine the antimicrobial and cytotoxic activities of different leaf extracts of A. majus using an established protocol. Different extracts were prepared using increasingly polar solvents. The antimicrobial activity of the extracts was determined using the disc diffusion method, and the cytotoxic activity of the extracts was assessed by the brine shrimp lethality bioassay. Exposure of the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli, Haemophilus influenzae and Proteus spp. bacterial strains to the different extracts revealed potential antimicrobial activity measured by zones of inhibition in the range of 0–20 mm. The cytotoxicity results showed an incremental rise in shrimp larvae mortality depending on the extract concentration, reaching 100% mortality at a concentration of 1000 μg/ml for all extracts. The methanol extract had the lowest of all LC₅₀ values at 45.75 μg/ml. The LC₅₀ values in ascending order for the chloroform, hexane, ethyl acetate, water and butanol extracts are 179.41, 288.31, 305.19, 417.94 and 570.02 μg/ml, respectively. In conclusion, in vitro and in vivo studies of the isolated leaf extracts are needed to determine the therapeutic potential of this plant.

Interval-valued fuzzy threshold graph is an extension of fuzzy threshold graph. In this paper, interval-valued fuzzy threshold graph, interval-valued fuzzy alternating 4-cycle, and interval-valued fuzzy threshold dimension are defined, and certain properties are studied. It is demonstrated that every interval-valued fuzzy threshold graph can be treated as an interval-valued fuzzy split graph.

Membrane gas separation has been recognized as the main technology that is used in chemical engineering for hydrogen recovery, air separation, natural gas sweetening, helium recovery, natural gas dehydration, and so on. Membrane-based gas separation processes have great potential for these industrial applications because of their environmental friendliness, energy efficiency and ease of scale up. Mathematical modelling of the membrane-based gas separation process can be useful to predict the performance of such separation processes. An improved mathematical model has been implemented in this research for the separation of a binary gas mixture using a membrane separator. The finite difference method (FDM) is applied to predict the membrane gas separation behaviour. The method is helpful as it involves the least effort and computational time because algebraic equations are used instead of differential equations. Different configurations, such as single stage and double stage, are used in this study. The results of the FDM simulation are compared with the simulation results of the model and the experimental data of several membrane systems.

Dendrimers are highly branched nanostructures and are considered a building block in nanotechnology with a variety of suitable applications. In this paper, a vertex degree-based topological index, namely, the F-index, which is defined as the sum of cubes of a graph's vertex degrees, is studied for certain dendrimers. In this study, we present exact expressions for the F-index and F-polynomial of six infinite classes of nanostar dendrimers.

Energy plays a vital role in the development of any nation. However, that development increases pollution levels. Recycling and utilization have become major concerns of developing nations. The goal of this research is to utilize banana peels for the production of bioethanol by using the yeast Saccharomyces cerevisiae. The effects of hydrolysis factors were investigated, and the optimized combination of factors with response surface designs was found. The results show that 45.088% of ethanol was obtained at 1.50% v/v acid concentration, 91.02 °C temperature and 21.66 min retention time. Analysis of variance (ANOVA) correlation coefficients Pred R² = 0.8650 and Adj R² = 0.9782 indicates an excellent evaluation of the experimental data by a second-order polynomial regression model.

The basis of the concept of interval valued intuitionistic fuzzy sets was introduced by K. Atanassov. Interval valued intuitionistic models provide more precision, flexibility, and compatibility to a system than do classic fuzzy models. In this paper, three new types of product operations (direct product, lexicographic product, and strong product) of interval valued intuitionistic (S,T)–fuzzy graphs are defined. One of the most studied classes of fuzzy graphs are regular fuzzy graphs, which appear in many contexts. For example, r-regular fuzzy graphs with connectivity and edge-connectivity equal to r play a key role in designing reliable communication networks. Hence, we introduced the concepts of regular and totally regular interval valued intuitionistic (S,T)–fuzzy graphs. Likewise, we defined busy vertices and free vertices in interval valued intuitionistic (S,T)–fuzzy graphs and studied their images under an isomorphism, which are highly important in fuzzy social networks.

The present study was designed to prepare different extracts from the leaves and fruit of Omani Ziziphus jujuba (Z. jujube) and to determine their total phenols and flavonoids content, including antioxidant activity, by applying modified established methods. Different extracts were prepared by Soxhlet extraction with methanol of powdered samples of either leaves or fruit. Both extracts were separately suspended in water and fractionated using solvents of different polarities, namely, hexane, chloroform, ethyl acetate, butanol, methanol and water, in an increasing polarity pattern. The different parameters mentioned above were determined using Folin-Ciocalteu reagent (FCR), aluminium chloride (AlCl₃) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) methods, as applied to each assay. The maximum content of total phenols in leaves was detected in the ethyl acetate extract, and the lowest was in the water extract. A similar result was also obtained from fruit extracts of Ziziphus jujube. However, the maximum content of flavonoids was detected in chloroform extract, and the minimum content was observed in hexane extract, with a similar trend being observed for total flavonoids content in the case of fruit extracts. Both the leaf and fruit extracts exhibited significant antioxidant activity, with the maximum percentage of inhibition being obtained in chloroform and hexane extracts and the lowest inhibition in the ethyl acetate extract. The present study demonstrates that all polar extracts of Omani Z. jujuba have significant antioxidant effects. This report is the first in Oman describing total phenols and flavonoids content, including assessment of antioxidant activity, of the extracts of Omani Z. jujube. Therefore, the active polar extracts of Omani Z. jujuba could be candidates for use as antibiotics.

In many real world problems, data sometimes comes from n agents (n ≥ 2), i.e., “multipolar information” exists. This information cannot be well-represented by means of fuzzy graphs or bipolar fuzzy graphs. Therefore, m-polar fuzzy set theory is applied to graphs to describe the relationships among several individuals. In this paper, some operations are defined to formulate these graphs. Some properties of strong m-polar fuzzy graphs, self-complementary m-polar fuzzy graphs and self-complementary strong m-polar fuzzy graphs are discussed.

Undoped and Pb-doped CdS (CdS:Pb) thin films were prepared on glass substrates by a spray technique using a perfume atomizer. The effects of Pb doping on the structural, morphological and optoelectrical properties of CdS thin films were studied. All of the films are polycrystalline in nature exhibiting hexagonal crystal structure. Crystallite size estimated from the Scherrer formula increased from 18.42 nm to 34.76 nm with increases in Pb doping concentration. The expansion of lattice parameters experienced with Pb doping might be due to the larger ionic radius of Pb²⁺ ions compared to that of the host Cd²⁺ ions. Increased optical transparency is observed for the doped films and the optical band gap experienced band bowing with increase in Pb doping concentration. Electrical resistivity values of the films were found to be on the order of 10¹ Ω cm. From the obtained results, it is observed that the CdS thin film coated with 6 wt.% Pb doping concentration exhibit better structural, morphological, optical and electrical properties.