PBAT/organoclay composite films: preparation and properties

Environmental problems caused by the increased waste associated with short-term use of plastic materials, particularly by the food packaging industry, prompted the search for biodegradable alternatives. This contribution studied one of these alternatives, poly(butylene adipate-co-terephthalate)—PBAT, a polymer that is fully biodegradable in common landfills, compounded with a small amount of Cloisite 20A organoclay. Materials were mixed in a laboratory internal mixer and films prepared in a chill roll extruder. Results show that the presence of organoclay does not increase degradation of the polymer matrix during processing, nor affects its crystallization characteristics. However, organoclay addition significantly diminished oxygen and carbon dioxide permeability of the films, making them a very interesting alternative for the food packaging industry.     

Electrodeposition of Zn–SiC nanocomposite coatings

Zn–SiC composite coatings were obtained on mild steel substrate by electrodeposition technique with high-current efficiency. A slightly acidic chloride bath, containing SiC nanoparticles and gelatine as additive, was used. The electrodeposition was carried out under galvanostatic control with pulsed direct current; the effect of experimental parameters (temperature, average current density and particles concentration) on composition, morphology and structure of the deposit was studied. Coatings were characterized by means of scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffractometry and Vickers microhardness measurements. Zn–SiC electrodeposits with the best characteristics were obtained by performing electrodepositions at 45 °C, with 20 g L^?1 SiC in the bath and with average current density in the range 100–150 mA cm^?2. Under these experimental conditions, homogeneous and compact coatings, with low-grain size and SiC content ranging from 1.7 to 2.1 wt%, were found to be electrodeposited. Microhardness measurements showed for these deposits an increase of about 50 % with respect to those without nanoparticles obtained in the same experimental conditions.     

CD8+ T Cell Senescence: Lights and Shadows in Viral Infections,Autoimmune Disorders and Cancer

CD8⁺ T lymphocytes are a heterogeneous class of cells that play a crucial role in the adaptive immune response against pathogens and cancer. During their lifetime, they acquire cytotoxic functions to ensure the clearance of infected or transformed cells and, in addition, they turn into memory lymphocytes, thus providing a long-term protection. During ageing, the thymic involution causes a reduction of circulating T cells and an enrichment of memory cells, partially explaining the lowering of the response towards novel antigens with implications in vaccine efficacy. Moreover, the persistent stimulation by several antigens throughout life favors the switching of CD8⁺ T cells towards a senescent phenotype contributing to a low-grade inflammation that is a major component of several ageing-related diseases. In genetically predisposed young people, an immunological stress caused by viral infections (e.g., HIV, CMV, SARS-CoV-2), autoimmune disorders or tumor microenvironment (TME) could mimic the ageing status with the consequent acceleration of T cell senescence. This, in turn, exacerbates the inflamed conditions with dramatic effects on the clinical progression of the disease. A better characterization of the phenotype as well as the functions of senescent CD8⁺ T cells can be pivotal to prevent age-related diseases, to improve vaccine strategies and, possibly, immunotherapies in autoimmune diseases and cancer.     

Use of a liquid chromatograph-ion trap mass spectrometer for end-group characterization of various polyethoxylate materials

The separation and detection properties of various ethoxylated polymers were investigated with atmospheric pressure ionization liquid chromatography/mass spectrometry (LC/MS). Interesting chromatographic elution behavior based on functionality was noted. LC/MS using in-source CID (collision-induced dissociation) and tandem mass spectrometry (MS/MS) detection was compared for end-group identification. Excellent end-group identification was achieved when the end-group molecular weight (MW) was greater than 100 Da and the average MW of the polymer was less than 400 Da by both MS/MS and in-source CID. In cases where the end-group MW was less than 100 Da, because of the low mass cut-off in a quadrapole ion trap analyzer, in-source CID produced the only characteristic end-group ions. The use of a dual scan function allowed investigation of the oligomeric distribution followed by a narrow low-mass scan using in-source CID to generate end-group information. This approach is applicable on instruments without MS/MS capability.     

Mechanisms and Kinetics of Liquid Silicon Oxidation During Industrial Refining

During oxidative ladle refining (OLR) of silicon, the metal surface is partly oxidized, resulting in the formation of a condensed silica fume (SiO₂). This fugitive emission of silica represents a potential health hazard to the workers in the silicon and ferrosilicon industry. In the current work, industrial measurement campaigns aimed at recording the fume generation during OLR were performed at the Elkem Salten plant in Norway. The measured amounts of silica produced were 2.5–5.1?kg/h, depending on the gas flow rate in the refining process. The rate of silica production correlates with the total flow rate and amount of air in the purge gas, and increases as the flow rate increases. The results of this work suggest that fume generation during OLR primarily results from oxidation of the exposed metal surface, with oxygen transport from the surrounding atmosphere to the metal surface being the limiting factor. Other identified mechanisms of SiO₂ formation were splashing of the metal and/or oxidation of SiO gas carried with the refining purge gas.     

Active Oxidation of Liquid Silicon: Experimental Investigation of Kinetics

Small scale laboratory experiments on the oxidation of liquid silicon have reproduced important features of the industrial refining of liquid silicon: active oxidation led to the formation of amorphous silica spheres as a reaction product. The boundary condition for active oxidation in terms of maximum oxygen partial pressure in the bulk gas was found to lie between 2·10^?3 and 5·10^?3?atm at T?=?1,500?°C. The active oxidation of liquid silicon had linear kinetics, and the rate was proportional to bulk oxygen partial pressure and the square root of the linear gas flow rate, consistent with viscous flow mass transfer theory. Classical theory for unconstrained flow over a flat plate led to mass transfer rates for SiO_(g) which were 2–3 times slower than observed. However, computational fluid dynamic modeling to take into account the effects of reactor tube walls on flow patterns yielded satisfactory agreement with measured volatilization rates.     

Highly Efficient Alkyne Hydroarylation with Chelating Dicarbene Palladium(II) and Platinum(II) Complexes

1 We report on a novel reaction protocol for the coupling of arenes with alkynes (the Fujiwara reaction), yielding products of formal trans‐hydroarylation of the triple bond. The protocol makes use of a chelating N‐heterocyclic dicarbene palladium(II) complex as catalyst and allows us to perform the reaction in a few hours with only 0.1 mol % catalyst yielding the trans‐hydroarylation product in high yields and with excellent selectivity. We discuss the applicability of this reaction protocol, which appears at present quite general with respect to the alkyne, albeit limited to electron‐rich arenes. We also present the results of catalyst optimisation with respect to the nature of the nitrogen substituents in the carbene units, of the bridging group between the carbene units and of the coordinated anionic ligands. Finally, we also discuss the catalytic performance of a related chelating dicarbene complex of platinum(II).     

The GAUGAA Motif Is Responsible for the Binding between circSMARCA5 and SRSF1 and Related Downstream Effects on Glioblastoma Multiforme Cell Migration and Angiogenic Potential

Circular RNAs (circRNAs) are a large class of RNAs with regulatory functions within cells. We recently showed that circSMARCA5 is a tumor suppressor in glioblastoma multiforme (GBM) and acts as a decoy for Serine and Arginine Rich Splicing Factor 1 (SRSF1) through six predicted binding sites (BSs). Here we characterized RNA motifs functionally involved in the interaction between circSMARCA5 and SRSF1. Three different circSMARCA5 molecules (Mut1, Mut2, Mut3), each mutated in two predicted SRSF1 BSs at once, were obtained through PCR-based replacement of wild-type (WT) BS sequences and cloned in three independent pcDNA3 vectors. Mut1 significantly decreased its capability to interact with SRSF1 as compared to WT, based on the RNA immunoprecipitation assay. In silico analysis through the “Find Individual Motif Occurrences” (FIMO) algorithm showed GAUGAA as an experimentally validated SRSF1 binding motif significantly overrepresented within both predicted SRSF1 BSs mutated in Mut1 (q-value = 0.0011). U87MG and CAS-1, transfected with Mut1, significantly increased their migration with respect to controls transfected with WT, as revealed by the cell exclusion zone assay. Immortalized human brain microvascular endothelial cells (IM-HBMEC) exposed to conditioned medium (CM) harvested from U87MG and CAS-1 transfected with Mut1 significantly sprouted more than those treated with CM harvested from U87MG and CAS-1 transfected with WT, as shown by the tube formation assay. qRT-PCR showed that the intracellular pro- to anti-angiogenic Vascular Endothelial Growth Factor A (VEGFA) mRNA isoform ratio and the amount of total VEGFA mRNA secreted in CM significantly increased in Mut1-transfected CAS-1 as compared to controls transfected with WT. Our data suggest that GAUGAA is the RNA motif responsible for the interaction between circSMARCA5 and SRSF1 as well as for the circSMARCA5-mediated control of GBM cell migration and angiogenic potential.     

N-(Anilinoethyl)amide Melatonergic Ligands with Improved Water Solubility and Metabolic Stability

The MT₂-selective melatonin receptor ligand UCM765 (N-(2-((3-methoxyphenyl)(phenyl)amino)ethyl)acetamide), showed interesting sleep inducing, analgesic and anxiolytic properties in rodents, but suffers from low water solubility and modest metabolic stability. To overcome these limitations, different strategies were investigated, including modification of metabolically liable sites, introduction of hydrophilic substituents and design of more basic derivatives. Thermodynamic solubility, microsomal stability and lipophilicity of new compounds were experimentally evaluated, together with their MT₁ and MT₂ binding affinities. Introduction of a m-hydroxymethyl substituent on the phenyl ring of UCM765 and replacement of the replacement of the N,N-diphenyl-amino scaffold with a N-methyl-N-phenyl-amino one led to highly soluble compounds with good microsomal stability and receptor binding affinity. Docking studies into the receptor crystal structure provided a rationale for their binding affinity. Pharmacokinetic characterization in rats highlighted higher plasma concentrations for the N-methyl-N-phenyl-amino derivative, consistent with its improved microsomal stability and makes this compound worthy of consideration for further pharmacological investigation.     

Computer-Aided Search for 5-Arylideneimidazolone Anticancer Agents Able To Overcome ABCB1-Based Multidrug Resistance

ABCB1 modulation is an interesting strategy in the search for new anticancer agents that can overcome multidrug resistance (MDR). Hence, 17 new 5-arylideneimidazolones containing an amine moiety, as potential ABCB1 inhibitors, were designed, synthesized, and investigated. The series was tested in both parental (PAR) and multidrug-resistant (MDR) ABCB1-overexpressing T-lymphoma cancer cells using cytotoxicity assays. The ABCB1-modulating activity was examined in rhodamine 123 accumulation tests, followed by Pgp-Glo™ Assay to determine the influence of the most active compounds on ATPase activity. Lipophilic properties were assessed both, in silico and experimentally (RP-TLC). Pharmacophore-based molecular modelling toward ABCB1 modulation was performed. The studies allowed the identification of anticancer agents (p-fluorobenzylidene derivatives) more potent than doxorubicin, with highly selective action on MDR T-lymphoma cells (selectivity index >40). Most of the investigated compounds showed ABCB1-modulating action; in particular, two 5-benzyloxybenzylidene derivatives displayed activity nearly as strong as that of tariquidar.