Transient analysis of intermittent multijet sprays

This paper analyzes the transient characteristics of intermittent sprays produced by the single-point impact of multiple cylindrical jets. The aim is to perform a transient analysis of the intermittent atomization process to study the effect of varying the number of impinging jets in the hydrodynamic mechanisms of droplet formation. The results evidence that hydrodynamic mechanisms underlying the physics of ligament fragmentation in 2-impinging jets sprays also apply to sprays produced with more than 2 jets during the main period of injection. Ligaments detaching from the liquid sheet, as well as from its bounding rim, have been identified and associated with distinct droplet clusters, which become more evident as the number of impinging jets increases. Droplets produced by detached ligaments constitute the main spray, and their axial velocity becomes more uniformly distributed with 4-impinging jets because of a delayed ligament fragmentation. Multijet spray dispersion patterns are geometric depending on the number of impinging jets. Finally, an analysis on the Weber number of droplets suggests that multijet sprays are more likely to deposit on interposed surfaces, thus becoming a promising and competitive atomization solution for improving spray cooling.     

Synthesis of environmentally friendly,magnetic acid-type calix[4]arene catalyst for obtaining Biginelli adducts

An immobilized p-sulfonic acid calix[4]arene was synthesized on the surface of silica-coated Fe₃O₄ nanoparticles. Due to the combination of the magnetic recovery and the acid properties, it acted as a robust, safe and environmentally friendly catalyst for the one-pot synthesis of Biginelli adducts under microwave irradiation and solvent-free conditions. A series of Biginelli adducts were obtained in moderate to excellent yields, and most importantly, the catalyst could be easily recovered by an external magnet and reused five times without significant loss of catalytic activity (ca. 80% yield for all reuses using 0.64 mol% of the catalyst).     

Chemical Composition and Antioxidant,Anti-Inflammatory,and Enzyme Inhibitory Activities of an Endemic Species from Southern Algeria: Warionia saharae

Warionia saharae Benth. & Coss. (Asteraceae) is an endemic species of North Africa naturally grown in the southwest of the Algerian Sahara. In the present study, this species’ hydromethanolic leaf extract was investigated for its phenolic profile characterized by ultra-high-performance liquid chromatography coupled with a diode array detector and an electrospray mass spectrometer (UHPLC-DAD-ESI/MS). Additionally, the chemical composition of W. saharae was analyzed by gas chromatography–mass spectrometry, and its antioxidant potential was assessed through five in vitro tests: DPPH^● scavenging activity, ABTS^●+ scavenging assay, galvinoxyl scavenging activity, ferric reducing power (FRP), and cupric reducing antioxidant capacity. The UHPLC-DAD-ESI/MS analysis allowed the detection and quantification of 22 compounds, with taxifolin as the dominant compound. The GC–MS analysis allowed the identification of 37 compounds, and the antioxidant activity data indicate that W. saharae extract has a very high capacity to capture radicals due to its richness in compounds with antioxidant capacity. The extract also showed potent α-glucosidase inhibition as well as a good anti-inflammatory activity. However, weak anti-α-amylase and anticholinesterase activities were recorded. Moreover, an in silico docking study was performed to highlight possible interactions between three significant compounds identified in W. saharae extract and α-glucosidase enzyme.     

Parameter Identification of Damage Models Using Genetic Algorithms

One of the most widely employed models to evaluate ductile damage and fracture is due to Gurson. An inconvenience of the model is that several material parameters must be determined in order to represent adequately a given experimental behavior. Determination of such parameters is not trivial but can be performed by means of inverse analyses using optimization procedures. In this work, the material parameters are sought by fitting force vs. displacement curves computed using finite element simulation to experimental curves obtained from tensile tests. The resulting optimization problem is non-convex and may present several local minima, thereby posing some difficulties to gradient-based optimization procedures due to the strong dependence on initial estimates of the design variables (the material parameters in this case). An approach based on a genetic algorithm is used in an attempt to avoid this problem. This strategy makes also possible to exploit the parallel nature of evolutionary algorithms as, at each generation, the evaluation of the fitness function of one individual is independent of the fitness of the rest of the population. In this particular implementation, each individual is represented by a gray encoding sequence of genes, the parental selection is performed by means of a tournament selection, the crossover probability is 0.8 and the probability of mutation is 0.05.     

Influence of Harvest Time on the Chemical Profile of Pereskia aculeate Mill. Using Paper Spray Mass Spectrometry

This study evaluated the physicochemical characteristics and the production of bioactive compounds of Pereskia aculeata Mill. at different harvest times. Here, we performed a qualitative evaluation of the chemical profile by paper spray mass spectrometry (PSMS), the phenolic acid and flavonoid profile by high-performance liquid chromatography (HPLC), antioxidant activity, total carotenoids, total phenolic compounds, total flavonoids, total anthocyanins, color characteristics, total soluble solids (TSS), total solids (TS), pH, and total titratable acidity (TTA). The chemical profile was not affected, with the exception of 4,5-dimethyl-2,6-octadiene and azelaic acid, which was only identified in the leaves harvested during the winter. The content of four phenolic acids and three flavonoids were analyzed; out of these, no significant amounts of ellagic acid and quercetin were detected. There was no difference in production of bioactive compounds between seasons, reflecting the antioxidant activity, which also did not differ. Brightness, chroma, and leaf pH were the only physicochemical characteristics that did not vary between seasons.     

Drug Repurposing and De Novo Drug Discovery of Protein Kinase Inhibitors as New Drugs against Schistosomiasis

Schistosomiasis is a neglected tropical disease affecting more than 200 million people worldwide. Chemotherapy relies on one single drug, praziquantel, which is safe but ineffective at killing larval stages of this parasite. Furthermore, concerns have been expressed about the rise in resistance against this drug. In the absence of an antischistosomal vaccine, it is, therefore, necessary to develop new drugs against the different species of schistosomes. Protein kinases are important molecules involved in key cellular processes such as signaling, growth, and differentiation. The kinome of schistosomes has been studied and the suitability of schistosomal protein kinases as targets demonstrated by RNA interference studies. Although protein kinase inhibitors are mostly used in cancer therapy, e.g., for the treatment of chronic myeloid leukemia or melanoma, they are now being increasingly explored for the treatment of non-oncological conditions, including schistosomiasis. Here, we discuss the various approaches including screening of natural and synthetic compounds, de novo drug development, and drug repurposing in the context of the search for protein kinase inhibitors against schistosomiasis. We discuss the status quo of the development of kinase inhibitors against schistosomal serine/threonine kinases such as polo-like kinases (PLKs) and mitogen-activated protein kinases (MAP kinases), as well as protein tyrosine kinases (PTKs).     

Piper tectoniifolium Kunth: A New Natural Source of the Bioactive Neolignan (−)-Grandisin

The Piper species are a recognized botanical source of a broad structural diversity of lignans and its derivatives. For the first time, Piper tectoniifolium Kunth is presented as a promising natural source of the bioactive (−)-grandisin. Phytochemical analyses of extracts from its leaves, branches and inflorescences showed the presence of the target compound in large amounts, with leaf extracts found to contain up to 52.78% in its composition. A new HPLC-DAD-UV method was developed and validated to be selective for the identification of (−)-grandisin being sensitive, linear, precise, exact, robust and with a recovery above 90%. The absolute configuration of the molecule was determined by X-ray diffraction. Despite the identification of several enantiomers in plant extracts, the major isolated substance was characterized to be the (−)-grandisin enantiomer. In vascular reactivity tests, it was shown that the grandisin purified from botanical extracts presented an endothelium-dependent vasorelaxant effect with an IC₅₀ of 9.8 ± 1.22 μM and around 80% relaxation at 30 μM. These results suggest that P. tectoniifolium has the potential to serve as a renewable source of grandisin on a large scale and the potential to serve as template for development of new drugs for vascular diseases with emphasis on disorders related to endothelial disfunction.     

Kinetic studies for sorption of amino acids using a strong anion-exchange resin. Effect of ionic strength

This work deals with the influence of the ionic strength on the sorption of L-phenylalanine and L-tyrosine by a strong basic anion-exchange resin, converted to the hydroxide form with sodium hydroxide. Equilibrium uptake isotherms were obtained for phenylalanine and tyrosine by carrying out batch experiments at different ionic strength values of the solution. The model used to correlate these results is the modified Langmuir equation which has been applied with success to biological systems. Batch kinetic experiments were performed using a packed bed of differential length inserted in a liquid circulation loop and in which the ionic strength of the solution was varied. Moreover, an experiment at variable pH for tyrosine was also performed. Experimental transient concentration profiles were compared to those predicted by the pore diffusion model and enabled the estimation of the intraparticle diffusivities for phenylalanine and tyrosine.     

An N-capping asparagine–lysine–proline (NKP) motif contributes to a hybrid flexible/stable multifunctional peptide scaffold

Structural diversity drives multiple biological activities and mechanisms of action in linear peptides. Here we describe an unusual N-capping asparagine-lysine-proline (NKP) motif that confers a hybrid multifunctional scaffold to a computationally designed peptide (PaDBS1R7). PaDBS1R7 has a shorter α-helix segment than other computationally designed peptides of similar sequence but with key residue substitutions. Although this motif acts as an α-helix breaker in PaDBS1R7, the Asn5 presents exclusive N-capping effects, forming a belt to establish hydrogen bonds for an amphipathic α-helix stabilization. The combination of these different structural profiles was described as a coil/N-cap/α-helix scaffold, which was also observed in diverse computational peptide mutants. Biological studies revealed that all peptides displayed antibacterial activities. However, only PaDBS1R7 displayed anticancer properties, eradicated Pseudomonas aeruginosa biofilms, decreased bacterial counts by 100–1000-fold in vivo, reduced lipopolysaccharide-induced macrophages stress, and stimulated fibroblast migration for wound healing. This study extends our understanding of an N-capping NKP motif to engineering hybrid multifunctional peptide drug candidates with potent anti-infective and immunomodulatory properties.

An unusual N-capping asparagine-lysine-proline (5NKP7) motif yields a coil/N-cap/α-helix multifunctional scaffold in a computer-made peptide selective for anionic surfaces and with anticancer, antibacterial, antibiofilm, anti-infective (in vivo), and immunomodulatory potential.     

Electropolymerized molecularly imprinted polymers: perceptions based on recent literature for soon-to-be world-class scientists

Electropolymerized molecularly imprinted polymers (e-MIPs) are interesting selective electrochemically produced materials that imitate biological antibody–antigen systems. This review of recent developments (2018–2020) on the application of e-MIPs in analytical chemistry introduces beginners to this promising field of research, describing their development, common functional monomers, applied characterization techniques, and the instrumental detection techniques used. However, it also intends to tell experienced readers some of the advances and trends: the use of graphene and nanomaterials, recurring to synergetic computational studies (to predict and understand polymerization and molecular imprinted polymer–analyte interactions), the simultaneous detection of more than one analyte, multiplex e-MIP systems, enzymatic template removal, using epitopes as templates for large molecules and bacteria, or the application of electrochemical tags.