SAID SHEHATA

We report the optimized design and theoretical analysis of broadband omnidirectional mirrors made of silicon nanostructures. The design principle is based on regulating the electrochemical etching process of single-crystalline silicon substrates in an acidic solution using a train of sinusoidal current waveforms with tightly-spaced frequencies. The individual frequency of the etching current waveform is calibrated to produce a specific photonic band in the reflectance spectrum. A linear relationship is obtained between the frequency of the current signal and the resonant position of the photonic band. The frequency range of the etching waveform is selected to produce a broad photonic peak resulting from the bandgap overlap among multiple photonic bands associated with the individual frequency of each current signal. The transfer matrix method is utilized to calculate the angular reflectance spectra of the experimentally obtained omnidirectional mirrors for both transverse electric (TE) and transverse magnetic (TM) polarization of the incident light. Good agreement is found between the experimental and theoretical reflectivity spectra.

A gold nanoparticle/graphitic carbon nitride heterostructure nanocomposite was synthesized via an in-situ chemical reduction of Au3+ on the surface of graphitic carbon nitride and was applied for the non-invasive electrochemical detection of uric acid (UA) in human saliva. In this configuration, gold nanoparticles (Au-NPs) acted as highly active electrocatalytic sites, while graphitic carbon nitride (g-C3N4) served as a high-surface-area scaffold facilitating uniform nanoparticles dispersion and efficient electron transfer. Morphological and elemental characterization using scanning electron microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), BET analysis, and infrared spectroscopy (IR) confirmed the homogeneous distribution of Au-NPs anchored to the g-C3N4 sheets. Furthermore, electrochemical characterization was performed through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Electrochemical measurements demonstrated that Au-NPs@g-C3N4/CPE generated significantly higher UA oxidation peak currents compared with bare CPE. Under optimized pH conditions, accumulation potential, and differential pulse parameters the sensor exhibited a well-defined linear calibration range 0.5–10.0 μM (r = 0.9943) with a detection limit of 0.31 μM uric acid. Selectivity tests in artificial saliva showed negligible signal deviations (≤ ±2 %) in the presence of common salivary interferents such as ascorbic acid, creatinine, and glucose. Spike and recovery experiments using actual saliva samples achieved recoveries of 95.56-98.27 % confirming high analytical accuracy in complex biological matrices. Furthermore, the electrode retained over 90 % of its initial response after 60 days of ambient storage indicating excellent stability. The synergistic integration of Au-NPs with g-C3N4 significantly enhanced catalytic activity, electron transport, and UA adsorption making the Au-NPs@g-C3N4/CPE a cost-effective, sensitive, and reliable platform for point-of-care UA monitoring in saliva for clinical diagnostics and health applications.

A gold nanoparticle/graphitic carbon nitride heterostructure nanocomposite was synthesized via an in-situ chemical reduction of Au3+ on the surface of graphitic carbon nitride and was applied for the non-invasive electrochemical detection of uric acid (UA) in human saliva. In this configuration, gold nanoparticles (Au-NPs) acted as highly active electrocatalytic sites, while graphitic carbon nitride (g-C3N4) served as a high-surface-area scaffold facilitating uniform nanoparticles dispersion and efficient electron transfer. Morphological and elemental characterization using scanning electron microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), BET analysis, and infrared spectroscopy (IR) confirmed the homogeneous distribution of Au-NPs anchored to the g-C3N4 sheets. Furthermore, electrochemical characterization was performed through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Electrochemical measurements demonstrated that Au-NPs@g-C3N4/CPE generated significantly higher UA oxidation peak currents compared with bare CPE. Under optimized pH conditions, accumulation potential, and differential pulse parameters the sensor exhibited a well-defined linear calibration range 0.5–10.0 μM (r = 0.9943) with a detection limit of 0.31 μM uric acid. Selectivity tests in artificial saliva showed negligible signal deviations (≤ ±2 %) in the presence of common salivary interferents such as ascorbic acid, creatinine, and glucose. Spike and recovery experiments using actual saliva samples achieved recoveries of 95.56-98.27 % confirming high analytical accuracy in complex biological matrices. Furthermore, the electrode retained over 90 % of its initial response after 60 days of ambient storage indicating excellent stability. The synergistic integration of Au-NPs with g-C3N4 significantly enhanced catalytic activity, electron transport, and UA adsorption making the Au-NPs@g-C3N4/CPE a cost-effective, sensitive, and reliable platform for point-of-care UA monitoring in saliva for clinical diagnostics and health applications.

The 2024 outbreak of Highly Pathogenic Avian Influenza (HPAI) H5N1 in U.S. dairy cattle represents a significant change in the behavior of zoonotic influenza viruses. Previously, H5N1 was primarily an avian pathogen with limited infection in mammals. The emergence of clade 2.3.4.4b H5N1 in dairy herds across multiple states reveals the virus’s adaptation to mammalian hosts and highlights its potential for zoonotic transmission, raising important concerns for public health, veterinary medicine, and agriculture. The virus demonstrated unique tropism for mammary tissue, with high viral loads detected in milk. Genomic analysis identified mutations that enhance binding to mammalian receptors and facilitate systemic spread. Viral RNA was found in raw milk, posing food safety risks; however, standard pasteurization effectively inactivated the virus. Epidemiological data indicate the outbreak likely began with spillover from wild birds or contaminated fomites, followed by efficient local transmission within herds. Forty-one human cases linked to infected dairy operations were confirmed. The outbreak caused significant economic losses due to decreased milk production and trade restrictions. Although human-to-human transmission remains low, the zoonotic risk requires urgent attention. The 2024 HPAI H5N1 outbreak in U.S. dairy cattle highlights critical gaps in surveillance, biosecurity, and coordination across sectors. A One Health approach integrating veterinary, public health, and environmental efforts is essential. Recommendations include improved surveillance, stringent biosecurity measures, occupational safety protocols, focused research on viral evolution, and investment in diagnostics and vaccines. These actions are vital to reduce risks, protect public health, and ensure the sustainability of the dairy industry against future zoonotic influenza threats.

The major objective was to investigate the protective capabilities of endophytic bacterial strains isolated from a number of medicinal plant species towards Aspergillus spp. secured from the internal tissues of fungi-infected peanuts. Among 32 fungal isolates surveyed for mycotoxin production in various culture media (PDA, RBCA, YES, CA), 10 isolates qualitatively producing AFB1, besides 10 OTA-producers, were assayed by HPLC for quantitative toxin production. Aspergillus spp. isolate Be 13 produced an extraordinary quantity of 1859.18 μg mL−1 AFB1, against the lowest toxin level of 280.40 μg mL−1 produced by the fungus isolate IS 4. The estimated amounts of OTA were considerably lower and fell in the range 0.88–6.00 μg mL−1; isolate Sa 1 was superior, while isolate Be 7 seemed inferior. Based on ITS gene sequencing, the highly toxigenic Aspergillus spp. isolates Be 13 and Sa 1 matched the description of A. novoparasiticus and A. ochraceus, respectively, ochraceus, respectively, which are present in GenBank with identity exceeding 99%. According to 16S rRNA gene sequencing, these antagonists labeled Ar6, Ma27 and So34 showed the typical characteristics of Pseudomonas aeruginosa, Bacillus subtilis and Bacillus velezensis, respectively, with similarity percentages of 99–100. The plant growth-promoting activity measurements of the identified endophytes indicated the production of 16.96–80.00 μg/100 mL culture medium of IAA. Phosphate-solubilizing capacity varied among endophytes from 2.50 to 21.38 μg/100 mL. The polysaccharide production pool of bacterial strains ranged between 2.74 and 6.57 mg mL−1. P. aeruginosa Ar6 and B. velezensis successfully produced HCN, but B. subtilis failed. The in vitro mycotoxin biodegradation potential of tested bacterial endophytes indicated the superiority of B. velezensis in degrading both mycotoxins (AFB1-OTA) with average percentage of 88.7; B. subtilis ranked thereafter (85.6%). The 30-day old peanut (cv. Giza 6) seedlings grown in gnotobiotic system severely injured due to infection with AFB1/OTA-producing fungi, an effect expressed in significant reductions in shoot and root growth traits. Simultaneous treatment with the endophytic antagonists greatly diminished the harmful impact of the pathogens; B. velezensis was the pioneer, not P. aeruginosa Ar6. In conclusion, these findings proved that several endophytic bacterial species have the potential as alternative tools to chemical fungicides for protecting agricultural commodities against mycotoxin-producing fungi.

This study addresses the pressing need for integrated environmental management in Kuwait’s central coastal arid zone, which faces increasing environmental challenges due to extensive human activities and climate change. The research employs remote sensing (RS), geographic information systems (GIS), land use and land cover (LU/LC) change detection, watershed analysis, and fieldwork to assess both regional paleo-drainage systems and local basins. The findings identify Al-Jahra and Al-Mutlla’a as areas highly susceptible to flash flooding and Al-Mutlla’a to sand encroachment. Morphometric analysis indicates that regional basins such as B2, B3, and B4 exhibit moderate drainage densities (0.37–4.9) and elongated shapes, which mitigate flash flood risks. In contrast, local basins like Jal-Az-Zor and Jal-Al-Atraf have higher drainage densities (1.9–2.4), steep slopes (>45°), and elevated relief ratios (19.13–20.4), making them more vulnerable to flash floods and erosion. Urbanization analysis reveals a 33.7% expansion in urban areas between 1986 and 2021, with a notable acceleration from 2013 to 2021 at a rate of 10 km2 per year. Additionally, sand movement and land-use changes have heightened landscape instability, particularly in inland desert dune fields, which remain highly dynamic. The findings highlight the need for tailored land management policies, including proposed trenching projects around Al-Jahra and integrated environmental management plans to enhance resilience against these hazards and support sustainable development.

Background: Infestation in greenhouse cucumber with the two-spotted spidermite (Tetranychus urticae Koch) commonly causes severe damage to crop quality and
quantity and increases crop production costs.
Objective: This study was conducted to investigate the efficacy of high-abamectinproducing
isolates of S. avermitilis against T. urticae-infested cucumber and to assess
their impact on biochemical stress markers in these vegetables.
Methods: In this study, 72 non-antagonistic Streptomyces were isolated from rhizospheric
soil samples collected from eight different locations in Egypt and screened for their
ability to produce the secondary metabolite, abamectin.
Results: The screening process identified two potent abamectin-producing isolates, EW8
and T2, which produced 42.7 and 29.6 μg/L abamectin, respectively, as confirmed by
LC-MS/MS analysis. According to DNA sequence analysis of the 16S rRNA gene, these
two isolates belong to the species S. avermitilis. The acaricidal activity of either culture
suspensions of S. avermitilis strains WE8 and T2, or their extracts containing abamectin,
against the mobile stages and egg hatchability of T. urticae was evaluated in the laboratory
and the greenhouse. Data on the mortality among the examined female mites and the
reduction in their number of eggs point out a potential acaricidal activity of the examined
strains of S. avermitilis and their extracts containing abamectin against T. urticaes. Furthermore,
the extracts containing abamectin from these two S. avermitilis strains induced
oxidative stress in the infested cucumber plants by T. urticaes, as indicated by increased
levels of malondialdehyde (MDA). However, the levels of MDA in T. urticae-infested cucumber
plants varied depending on the strain and the specific abamectin crude extract used.
Conclusion: S. avermitilis strains T2 or WE8, or their crude extract could be applied in
greenhouse cucumber plantations to combat red mite infestation.