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White rot, caused by Stromatinia cepivora (Anamorph: Sclerotium cepivorum Berk), is a serious soil-borne disease of the onion that restricts its cultivation and production worldwide. Herein, we isolated and characterized a plant growth-promoting rhizobacterium Stenotrophomonas maltophilia from healthy onion roots and an endophytic bacterium Serratia liquefaciens from healthy bean leaves. Both isolates showed strong fungistatic activity against S. cepivora using the dual culture and culture filtrate methods. This effect might be due to the presence of several volatile compounds, especially menthol in both culture filtrates as shown with a GC-MS analysis. Additionally, the root drench application of cell-free culture filtrates of S. maltophilia and S. liquefaciens significantly reduced the incidence and severity of white rot disease on treated onion plants, which was associated with the activation of both enzymatic (POX and PPO) and non-enzymatic (phenolics and flavonoids) antioxidant defense machineries of S. cepivora-infected onion plants. Moreover, the culture filtrates of both bacterial bioagents remarkably enhanced the growth (as expressed by root length, plant height, and number of leaves) and yield parameters (as indicated by bulb circumference, fresh weight of the bulb, and bulb yield per plot) of treated onion plants under field conditions during two successive seasons (2020/2021 and 2021/2022). This might be because of a reduced disease severity and/or the accumulation of the main auxin, indole-3-acetic acid (IAA), and its precursor, the amino acid tryptophan. Our findings suggest that both bioagents might be utilized as eco-friendly alternative control measures to reduce the utilization of chemical fungicides entirely or partially for the safer production of onion in S. cepivora-infested soils. [ABSTRACT FROM AUTHOR]

Strawberry fruits are subjected to many pathogens, especially the necrotrophic fungus Botrytis cinerea. Many salt compounds, plant extracts, and bio-agents were used to control gray mold in strawberry fruits caused by the fungus Botrytis cinerea. All the tested salt compounds reduced the mycelial growth of B. cinerea. The salt KH2PO4 was the most effective followed by the salt NaHCO3 and CaCl2 respectively. Fore disease severity, the highest concentration of any salt was the most effective in reducing disease severity. Spray strawberry fruits with three plant extract types, i.e., Garlic, Marjoram, and Thyme at two concentrations (10 and 20%) were effective in reducing mycelial growth. The highest effective concentration of Garlic extract in reducing disease severity was 20% compared with the other plant extracts and the control treatment. The results of the bio-agent experiment indicated that Trichoderma harzianum was the most effective in reducing the growth of B. cinerea in Petri dishes. In contrast, Trichoderma viride was the most effective one in reducing disease severity. All the tested fungicides gave sufficient control against strawberry fruit rot caused by the fungus B. cinerea in comparison with control during the two successive seasons. To the best of knowledge the allowable of the three used fungicides in strawberry fruits is unknown. So, one can say that strawberry fruits picked after spraying could not be marketed with apparent safety for human consumption until the strawberry fruits are free from any residues of the three fungicides. [ABSTRACT FROM AUTHOR]

The existence of coastal salt marshes along the Arabian Gulf and Red Sea shores and inland salt marshes led to many halophytes found in several regions of Saudi Arabia. Many grazing animals rely on marginal and neglected resources like halophytes. Consequently, the work objectives were to determine halophytic community diversity in this vital region and assess some halophytic species nutritional value in the studied area. Twelve plant species belonging to ten families were recorded in Al-Qunfudhah area from February 2018 to January 2020. Amaranthaceae was the dominant family, and chamaephyte was the predominant life form, which indicates a typical salt marches form. Among survived halophytic species, the highest importance value (IV) is found in Aeluropus lagopoides (87.02), Suaeda vermiculata (60.48); these plants are considered C4 pathway in protein biosynthesis. The results indicate that some halophytic species have high protein contents, fiber, and nitrogen-free extract, which render them an excellent source of forage. Such halophytic plant species may play an essential role in Saudi Arabia's welfare living in harsh arid regions by providing economic fodders throughout the year. In addition, exploring solutions to preserve wildlife plants from extinction is an essential step in protecting our ecosystem. [ABSTRACT FROM AUTHOR]

In this paper, a new tri-band metamaterial absorber based on crossed sun fractal structure for Radar Cross Section (RCS) reduction is presented. The proposed metamaterial absorber (MMA) exhibits three distinct absorption peaks at 2.2, 5.9 and 6.8 GHz with peak absorption values of 97, 91.6 and 93.3 % respectively. The proposed MMA unit cell is printed on FR-4 substrate with thickness 1.6 mm (0.0117λ0) and compact size 40 mm × 40 mm (0.293 λ0 × 0.293λ0), where λ0 is the free-space wavelength with respect to the lowest resonance frequency. Thanks to the new proposed fractal sun shape with sharp edges, we achieve the highest absorption rate at the lowest resonant frequency in comparison with the other published works. In addition, the simple equivalent circuit model is proposed to analyze and predict the frequency of the absorption phenomena of the proposed design. Radar target is characterized by Radar Cross Section (RCS). The surface currents and electric field distributions have been illustrated to understand the mechanism of the structure. In this paper we simulated and calculated the RCS of Perfect Electric Conductor (PEC) and compared this result by a PEC covered by metamaterial sheet. The proposed absorber structure can be used in different applications such as electro-magnetic protections, military and medical applications. All simulation results are performed using the Computer Simulation Technology (CST) Microwave Studio 2018 software, Advanced Design System (ADS) 2017 software, and Mathworks simulation tool MATLAB ver. 2011. In this paper, a new tri-band metamaterial absorber based on crossed sun fractal structure for Radar Cross Section (RCS) reduction is presented. The proposed metamaterial absorber (MMA) exhibits three distinct absorption peaks at 2.2, 5.9 and 6.8 GHz with peak absorption values of 97, 91.6 and 93.3 % respectively. The proposed MMA unit cell is printed on FR-4 substrate with thickness 1.6 mm (0.0117 λ0) and compact size 40 mm × 40 mm (0.293 λ0 × 0.293 λ0 ), where λ0 is the free-space wavelength with respect to the lowest resonance frequency. Thanks to the new proposed fractal sun shape with sharp edges, we achieve the highest absorption rate at the lowest resonant frequency in comparison with the other published works. In addition, the simple equivalent circuit model is proposed to analyze and predict the frequency of the absorption phenomena of the proposed design. Radar target is characterized by Radar Cross Section (RCS). The surface currents and electric field distributions have been illustrated to understand the mechanism of the structure. In this paper we simulated and calculated the RCS of Perfect Electric Conductor (PEC) and compared this result by a PEC covered by metamaterial sheet. The proposed absorber structure can be used in different applications such as electro-magnetic protections, military and medical applications. All simulation results are performed using the Computer Simulation Technology (CST) Microwave Studio 2018 software, Advanced Design System (ADS) 2017 software, and Mathworks simulation tool MATLAB ver. 2011. [ABSTRACT FROM AUTHOR]

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The present article's intent is to measure and identify the roller bearing inner race defect width and its corresponding characteristic frequency based on filtered time-domain vibration signal. In case localized fault occurs in a bearing, the rolling elements encounter some slippage as the rolling elements enter and leave the bearing load zone. As a consequence, the incidence of the impacts never reproduce exactly at the same position from one cycle to another. Moreover, when the position of the defect is moving with respect to the load distribution zone of the bearing, the series of impulses are modulated in amplitude in time-domain and the conforming Bearing Characteristic Frequencies (BCFs) arise in frequency domain. In order to verify the ability of time-domain in measuring the fault of rolling bearing, an artificial fault is introduced in the vehicle gearbox bearing: an orthogonal placed groove on the inner race with the initial width of 0.6mm approximately. The faulted bearing is a roller bearing quantification of the characteristic features relevant to the inner race bearing defect. It is located on the gearbox input shaft--on the clutch side. To jettison the frequency associated with interferential vibrations, the vibration signal is filtered with a band-pass filter based on an optimal daughter Morlet wavelet function whose parameters are optimized based on maximum Kurtosis (Kurt.). The residual signal is performed for the measurement of defect width. The proposed technique is used to analyse the experimental signal of vehicle gearbox rolling bearing. The experimental test stand is equipped with two dynamometer machines; the input dynamometer serves as an internal combustion engine, the output dynamometer introduces the load on the flange of the output joint shaft. The Kurtosis and Pulse Indicator (PI) are selected as the evaluation parameters of the de-noising effect. The results show the reliability of the proposed approach for identification and quantification of the characteristic features relevant to the inner race bearing defect. [ABSTRACT FROM AUTHOR]