Synthesis and free radical scavenging activity of coumarin derivatives containing a 2-methylbenzothiazoline motif

Coumarin and benzothiazole scaffolds can be found in a number of natural or synthetic antioxidants. In an effort to develop a novel radical scavenger and potential antioxidant, a series of coumarin derivatives containing 2‐methylbenzothiazoline motif and related compounds was synthesized and evaluated for their DPPH (1,1‐diphenyl‐2‐picrylhydrazyl) and ABTS^?+ (2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radicals scavenging activities. Among them, 7‐hydroxy‐3‐(2‐methyl‐2,3‐dihydrobenzo[d]thiazol‐2‐yl)‐2H‐chromen‐2‐one ( 3e ) has shown a significant free radical scavenging activity. From the structure–activity point of view, it was found that phenolic coumarin ring and benzothiazoline moiety in target compounds may contribute to the scavenging activity against free radicals.     

Analysis of Unconfined Compressive Strength of Rammed Earth Mixes Based on Artificial Neural Network and Statistical Analysis

Earth materials have been used in construction as safe, healthy and environmentally sustainable. It is often challenging to develop an optimum soil mix because of the significant variations in soil properties from one soil to another. The current study analyzed the soil properties, including the grain size distribution, Atterberg limits, compaction characteristics, etc., using multilinear regression (MLR) and artificial neural networks (ANN). Data collected from previous studies (i.e., 488 cases) for stabilized (with either cement or lime) and unstabilized soils were considered and analyzed. Missing data were estimated by correlations reported in previous studies. Then, different ANNs were designed (trained and validated) using Levenberg-Marquardt (L-M) algorithms. Using the MLR, several models were developed to estimate the compressive strength of both unstabilized and stabilized soils with a Pearson Coefficient of Correlation (R²) equal to 0.2227 and 0.766, respectively. On the other hand, developed ANNs gave a higher value for R² than MLR (with the highest value achieved at 0.9883). Thereafter, an experimental program was carried out to validate the results achieved in this study. Finally, a sensitivity analysis was carried out using the resulting networks to assess the effect of different soil properties on the unconfined compressive strength (UCS). Moreover, suitable recommendations for earth materials mixes were presented.     

Recovery of vanadium and nickel from heavy oil fly ash (HOFA): a critical review

Heavy oil fly ash “HOFA” is the fly ash generated in power stations using heavy oil as fuel. HOFA is considered a hazardous waste because it contains considerable amounts of heavy metals. However, it contains significant amounts of vanadium “V” and nickel “Ni”, which are precious metals for manufacturing processes. This paper presents a critical review of various approaches described in the literature for the recovery of V and Ni from HOFA, including processes of leaching, chemical precipitation, solvent extraction, and ion exchange. The optimum operational parameters and their effects on recovery efficiency are discussed. The digestion mixtures of strong mineral acids used for dissolving all metals present in HOFA are also highlighted. The leaching processes of V and Ni use mainly acidic and alkaline solutions. Bioleaching is a promising environmentally friendly approach for the recovery of V and Ni through using appropriate bacteria and fungi. After leaching, V and Ni compounds are recovered and purified using various techniques, including chemical precipitation, solvent extraction, and ion exchange. In most cases, V and Ni are recovered as thermally decomposable compounds that undergo calcination to produce V₂O₅ and NiO. Eventually, V and Ni are recovered as pure oxides in most approaches, but pure metals are obtained in exceptional procedures.

Overall flowchart of the recovery of V and Ni from HOFA showing the most common steps following the main three optional leaching approaches.     

Polyoxometalate supported on a magnetic Fe3O4/MIL-88A rod-like nanocomposite as an adsorbent for the removal of ciprofloxacin,tetracycline and cationic organic dyes from aqueous solutions

In this work, a magnetic H₃PW₁₂O₄₀/Fe₃O₄/MIL-88A (Fe) rod-like nanocomposite as a stable and effective ternary adsorbent was fabricated by the hydrothermal method and utilized for the removal of ciprofloxacin (CIP), tetracycline (TC) and organic dyes from aqueous solution. Characterization of the magnetic nanocomposite was accomplished by FT-IR, XRD, Raman spectroscopy, SEM, EDX, TEM, VSM, BET specific surface area and zeta potential analyses. The influencing factors on the adsorption potency of the H₃PW₁₂O₄₀/Fe₃O₄/MIL-88A (Fe) rod-like nanocomposite including initial dye concentration, temperature and adsorbent dose were studied. The maximum adsorption capacities of H₃PW₁₂O₄₀/Fe₃O₄/MIL-88A (Fe) for TC and CIP were 370.37 mg g⁻¹ and 333.33 mg g⁻¹ at 25 °C, respectively. In addition, the H₃PW₁₂O₄₀/Fe₃O₄/MIL-88A (Fe) adsorbent had high regeneration and reusability capacity after four cycles. In addition, the adsorbent was recovered through magnetic decantation and reused for three consecutive cycles without a considerable reduction in its performance. The adsorption mechanism was mainly ascribed to electrostatic and π–π interactions. According to these results, H₃PW₁₂O₄₀/Fe₃O₄/MIL-88A (Fe) can act as a reusable effective adsorbent for the fast elimination of tetracycline (TC), ciprofloxacin (CIP) and cationic dyes from aqueous solutions.

A magnetic Fe₃O₄/MIL-88A Fe rod-like nanocomposite containing H₃PW₁₂O₄₀ was fabricated and applied as a new magnetically recoverable ternary adsorbent to remove antibiotics and dyes from aqueous solutions.     

Ternary Copper Tungsten Sulfide (Cu2WS4) Nanoparticles Obtained through a Solvothermal Approach: A Bi-Functional Electrocatalyst for the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER)

In this work, Cu₂WS₄ nanoparticles have been synthesized via a solvothermal decomposition approach using a heterobimetallic single source precursor, WCu₂S₄(PPh₃)₃. The single source precursor, WCu₂S₄(PPh₃)₃, has been characterized using multinuclear NMR spectroscopy, while Cu₂WS₄ nanoparticles have been characterized by powder X-ray diffraction (PXRD) for which Rietveld refinement has been performed to authenticate the lattice structure of the decomposed product, Cu₂WS₄. Furthermore, FESEM and EDAX analyses have been performed to assess the morphology and composition of Cu₂WS₄. An electrochemical study in acidic as well as basic media suggested that Cu₂WS₄ nanoparticles possess efficient bifunctional activity towards electrochemical hydrogen as well as oxygen evolution reactions. Linear sweep voltammetry (LSV) performed in 0.5 N H₂SO₄ indicates an onset potential for the HER of 462 mV and a Tafel slope of 140 mV dec⁻¹. While LSV performed in 0.1 M KOH indicates an onset potential for the OER of 190 mV and a Tafel Slope of 117 mV dec⁻¹.     

Post‐COVID‐19 splenic infarction in a patient with chronic atrial fibrillation: A case report

We describe splenic infarction (SI), an infrequent condition, in an 82‐year‐old COVID‐19 patient with chronic atrial fibrillation (AF). COVID‐19 may cause thrombosis, and AF is a predisposing factor for splenic infarction. Suspicion of SI may be warranted in COVID‐19 patients with abdominal pain, especially if a predisposing factor exists.     

Eye bank versus surgeon prepared Descemet stripping automated endothelial keratoplasty tissues: Influence on adhesion force in a pilot study

Purpose:To evaluate and compare the biomechanical properties of the eye bank-prepared and surgeon prepared Descemet stripping automated endothelial keratoplasty (DSAEK) tissues.Methods:In this laboratory study, corneal tissues for research were randomly allocated in the following groups: a) surgeon-cut DSAEK and b) eye bank-prepared (pre-cut and pre-loaded) DSAEK. Endothelial cell loss (ECL), immunostaining for tight junction protein ZO-1, elastic modulus, and adhesion force were investigated.Results:ECL was not found to be significantly different between surgeon-cut DSAEK (7.8% ±6.5%), pre-cut DSAEK (8.6% ±2.3%), and pre-loaded DSAEK (11.1% ±4.8%) (P = 0.5910). ZO-1 was expressed equally across all groups. Surgeon-cut DSAEK grafts showed a significantly higher elastic modulus compared to pre-cut and pre-loaded DSAEK groups (P = 0.0047 and P < 0.0001, respectively). Adhesion force was significantly greater in the surgeon-cut DSAEK compared to pre-cut (P < 0.0001) or pre-loaded DSAEK groups (P = 0.0101).Conclusion:The laboratory data on the biomechanics of DSAEK grafts suggests that surgeon-cut DSAEK grafts present higher elastic modulus and adhesion force compared to eye bank-prepared DSAEK grafts.     

Exploring the anticancer activities of novel bioactive compounds derived from endophytic fungi: mechanisms of action,current challenges and future perspectives

Cancer is the second leading cause of death all around the world. The natural compounds derived from the endophytic flora of fungi are possible solutions to cancer treatment because they are safe for health, cost-effective, biocompatible and have fewer toxicity issues. The active ingredients in endophytic fungi that are responsible for anti-cancer activities are alkaloids, terpenoids, glycosides, saponin, peptides, steroids, phenols, quinones, and flavonoids. This review highlights the anti-cancer activities of entophytic fungus against human papillary thyroid carcinoma (IHH4), human pancreatic (PANC-1), ovarian (OVCAR-3), hepatic (HepG2), lung (A-549), human lymphoma (U937), human skin carcinoma (A431), breast (MCF-7), and Kaposi’s sarcoma. The emerging evidence suggested that bioactive compounds isolated from endophytic fungi showed their anti-cancer activities by revealing the disturbance of the microtubule network caused by increased levels of Bax and Bcl-2 proteins that triggers cell cycle arrest at the G2-M phase, by inhibiting the DNA replication via binding with topoisomerase II, by regulating the activity of extracellular signal-regulated kinase and NF-kB, by evaluating the levels of p21, p27, and cyclins B/D1/E that led to cell death by apoptosis and cell cycle arrest. This review will assist readers in better comprehending bioactive chemicals and the beneficial interaction between the fungal endophytes and medicinal plants.