Harmonic distortion levels in current power systems have increased due to technical advancements in industrial and renewable energy applications. So far, passive power filters have been widely employed to minimize harmonics and lessen their adverse effects. In this regard, this paper presents a novel bi-level design of damped double-tuned passive filters operating in a non-sinusoidal power system with nonlinearities at both the source and the load. A modern metaheuristic optimization technique known as wild horse optimization is applied to acquire the parameters of the used filters. Several objective functions, such as voltage total harmonic distortion, current total demand distortion, active power losses, and resonance-based metric minimization, were researched to improve the analyzed system's overall power quality performance. The mathematical derivations of the filter design expressions are given in detail. In the literature, there are several schemes for damped double-tuned filters. This paper investigates and analyses four schemes of this filter. The results are compared to those obtained from other metaheuristic optimization algorithms to ensure that the proposed algorithm produces the most effective outcomes. Statistical analysis is performed using many criteria to ensure the superiority of the proposed algorithm. Furthermore, depending on several assessment criteria, the analytical hierarchy process is employed to find the most effective candidate scheme. One of the schemes tested (scheme B) outperformed the others.

Infection of mammalian cells by SARS-CoV-2 coronavirus requires primary interaction between the receptor binding domain (RBD) of the viral spike protein and the host cell surface receptor angiotensin-converting enzyme 2 (ACE2) glycoprotein. Several mutations in the RBD of SARS-CoV-2 spike protein have been reported for several variants and resulted in wide spread of the COVID pandemic. For instance, the double mutations L452R and E484Q present in the Indian B.1.617 variant have been suggested to cause evasion of the host immune response. The common RBD mutations N501Y and E484K were found to enhance the interaction with the ACE2 receptor. In the current study, we analyzed the biosynthesis and secretion of the RBD double mutants L452R and E484Q in comparison to the wild-type RBD and the individual mutations N501 and E484K in mammalian cells. Moreover, we evaluated the interaction of these variants with ACE2 by means of expression of the S protein and co-immunoprecipitation with ACE2. Our results revealed that the double RBD mutations L452R and E484Q resulted in a higher expression level and secretion of spike S1 protein than other mutations. In addition, an increased interaction of these mutant forms with ACE2 in Calu3 cells was observed. Altogether, our findings highlight the impact of continuous S1 mutations on the pathogenicity of SARS-CoV-2 and provide further biochemical evidence for the dominance and high transmissibility of the double Indian mutations.

Azo dyes impact the environment and deserve attention due to their widespread use in textile and tanning industries and challenging degradation. The high temperature, pH, and salinity used in these industries render industrial effluent decolorization and detoxification a challenging process. An enrichment technique was employed to screen for cost-effective biodegraders of Direct Red 81 (DR81) as a model for diazo dye recalcitrant to degradation. Our results showed that three mixed bacterial cultures achieved ≥80% decolorization within 8 h of 40 mg/L dye in a minimal salt medium with 0.1% yeast extract (MSM-Y) and real wastewater. Moreover, these mixed cultures showed ≥70% decolorization within 24 h when challenged with dye up to 600 mg/L in real wastewater and tolerated temperatures up to 60 °C, pH 10, and 5% salinity in MSM-Y. Azoreductase was the main contributor to DR81 decolorization based on crude oxidative and reductive enzymatic activity of cell-free supernatants and was stable at a wide range of pH and temperatures. Molecular identification of azoreductase genes suggested multiple genes per mixed culture with a possible novel azoreductase gene. Metabolite analysis using hyphenated techniques suggested two reductive pathways for DR81 biodegradation involving symmetric and asymmetric azo-bond cleavage. The DR81 metabolites were non-toxic to nauplii and seeds. This study provided evidence for DR81 degradation using robust stress-tolerant mixed cultures with potential use in azo dye wastewater treatment.