Natural iron-containing minerals catalyze the degradation of polypropylene microplastics: a route to self-remediation learnt from the environment.

Virgin and environmentally aged polypropylene (PP) micropowders (V-PP and E-PP, respectively) were used as reference microplastics (MPs) in comparative photo- and thermo-oxidative ageing experiments performed on their mixtures with a natural ferrous sand (NS) and with a metal-free silica sand (QS). The ferrous NS was found to catalyze the photo-oxidative degradation of V-PP after both UV and simulated solar light irradiation. The catalytic activity in the V-PP/NS mixture was highlighted by the comparatively higher fraction of photo-oxidized PP extracted in dichloromethane, and the higher carbonyl index of the bulk polymer extracted with boiling xylene, when compared with the V-PP/QS mixture. Similarly, NS showed a catalytic effect on the thermal degradation (at T = 60 °C) of E-PP. The results obtained indicate that, under suitable environmental conditions (in this case, an iron-containing sediment or soil matrix, combined with simulated solar irradiation), the degradation of some types of MPs could be much faster than anticipated. Given the widespread presence of iron minerals (including the magnetite and iron-rich serpentine found in NS) in both coastal and mainland soils and sediments, a higher than expected resilience of the environment to the contamination by this class of pollutants is anticipated, and possible routes to remediation of polluted natural environments by eco-compatible iron-based minerals are envisaged.

Additive Manufacturing of Wet-Spun Polysulfone Medical Implants.

Research on additive manufacturing (AM) of high-performance polymers provides novel materials and technologies for advanced applications in different sectors, such as aerospace and biomedical engineering. The present article is contextualized in this research trend by describing a novel AM protocol for processing a polysulfone (PSU)/N-methyl-2-pyrrolidone (NMP) solution into medical implant prototypes. In particular, an AM technique involving the patterned deposition of the PSU/NMP mixture in a coagulation bath was employed to fabricate PSU implants with different predefined shape, fiber diameter, and macropore size. Scanning electron microscopy (SEM) analysis highlighted a fiber transversal cross-section morphology characterized by a dense external skin layer and an inner macroporous/microporous structure, as a consequence of the nonsolvent-induced polymer solidification process. Physical-chemical and thermal characterization of the fabricated samples demonstrated that PSU processing did not affect its macromolecular structure and glass-transition temperature, as well as that after post-processing PSU implants did not contain residual solvent or nonsolvent. Mechanical characterization showed that the developed PSU scaffold tensile and compressive modulus could be changed by varying the macroporous architecture. In addition, PSU scaffolds supported the in vitro adhesion and proliferation of the BALB/3T3 clone A31 mouse embryo cell line. These findings encourage further research on the suitability of the developed processing method for the fabrication of customized PSU implants.

The role of early synthetic materials degradation in the downfall of the Ansaldo A.1, an Italian World War I biplane fighter.

From the Pioneer Era of the aviation to World War I the evolution of aircraft technology and chemical synthesis enabled a unique coexistence of traditional craftsmanship, artistic decoration practices, and technological advancements. The study of the materials used in these early years of aviation is still an uncharted territory: a vast portion of remaining planes has been partially or completely repaired and restored, usually by total replacement of the fabric. The Italian biplane Ansaldo A.1 (1918) is a fighter aircraft and is one of the few planes in the world that still preserves its own original materials. In the last years, the fabric sections of the airplane have started to become brittle and loose cohesion, severely compromising the integrity of the aircraft, and resulting in a general alteration of the pictorial layers of the painted sections. A chemical investigation was undertaken to unveil the materials, and to elucidate the causes of the degradation. This study presents one of the first steps into the study of early historical aircrafts, defining the background for the conservation plans to preserve these objects for future generations.

Microplastic pollution in the sediments of interconnected lakebed, seabed, and seashore aquatic environments: polymer-specific total mass through the multianalytical "PISA" procedure.

The total mass of individual synthetic polymers present as microplastic (MP < 2 mm) pollutants in the sediments of interconnected aquatic environments was determined adopting the Polymer Identification and Specific Analysis (PISA) procedure. The investigated area includes a coastal lakebed (Massaciuccoli), a coastal seabed (Serchio River estuarine), and a sandy beach (Lecciona), all within a natural park area in Tuscany (Italy). Polyolefins, poly(styrene) (PS), poly(vinyl chloride) (PVC), polycarbonate (PC), poly(ethylene terephthalate) (PET), and the polyamides poly(caprolactame) (Nylon 6) and poly(hexamethylene adipamide) (Nylon 6,6) were fractionated and quantified through a sequence of selective solvent extractions followed by either analytical pyrolysis or reversed-phase HPLC analysis of the products of hydrolytic depolymerizations under acidic and alkaline conditions. The highest concentrations of polyolefins (highly degraded, up to 864 µg/kg of dry sediment) and PS (up to 1138 µg/kg) MPs were found in the beach dune sector, where larger plastic debris are not removed by the cyclic swash action and are thus prone to further aging and fragmentation. Surprisingly, low concentrations of less degraded polyolefins (around 30 µg/kg) were found throughout the transect zones of the beach. Positive correlation was found between polar polymers (PVC, PC) and phthalates, most likely absorbed from polluted environments. PET and nylons above their respective LOQ values were found in the lakebed and estuarine seabed hot spots. The pollution levels suggest a significant contribution from riverine and canalized surface waters collecting urban (treated) wastewaters and waters from Serchio River and the much larger Arno River aquifers, characterized by a high anthropogenic pressure.

New methodologies for the detection, identification, and quantification of microplastics and their environmental degradation by-products.

Sampling, separation, detection, and characterization of microplastics (MPs) dispersed in natural water bodies and ecosystems is a challenging and critical issue for a better understanding of the hazards for the environment posed by such nearly ubiquitous and still largely unknown form of pollution. There is still the need for exhaustive, reliable, accurate, reasonably fast, and cost-efficient analytical protocols allowing the quantification not only of MPs but also of nanoplastics (NPs) and of the harmful molecular pollutants that may result from degrading plastics. Here a set of newly developed analytical protocols, integrated with specialized techniques such as pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS), for the accurate and selective determination of the polymers most commonly found as MPs polluting marine and freshwater sediments are presented. In addition, the results of an investigation on the low molecular weight volatile organic compounds (VOCs) released upon photo-oxidative degradation of microplastics highlight the important role of photoinduced fragmentation at a molecular level both as a potential source of hazardous chemicals and as accelerators of the overall degradation of floating or stranded plastic debris.

Microplastics in fish meal: Contamination level analyzed by polymer type, including polyester (PET), polyolefins, and polystyrene.

Fish meal (FM) is an industrial product, mainly obtained from whole wild-caught fish, that is used as a high protein feedstuff component in aquaculture and intensive animal farming. Contamination of FM by microplastics (MPs), the synthetic polymer particles known to be nearly ubiquitous in the marine environment, is a likely consequence of their ingestion by zooplankton and other small marine animals that through the food chain end up in the fish commercialized not only for direct human consumption but also for the industrial production of FM. Unfortunately, analytical tools for quantifying contamination of FM by synthetic polymers are not available. A newly developed procedure described here allows quantification of the total amounts of polyolefins (including ethene and propene homo- and copolymers), polystyrene (PS), and poly(ethylene terephthalate) (PET), respectively, in FM. The multi-step procedure involves a sequence of solvent extractions, hydrolytic treatments to remove the biogenic matrix mainly consisting of proteins and some lipids, and selective depolymerization for PET. The gravimetric and SEC-UV techniques employed for the quantification of polyolefins and PS, respectively, only allowed to estimate their concentration in FM at around or below 100 mg/kg each, a more accurate quantification being prevented by the interference from the organic matrix and, in the case of polyolefins, by the limited sensitivity of the quantification by gravimetry. On the other hand, the contamination by PET MPs could accurately be quantified at 12.9 mg/kg based on the dry FM mass. Ways to overcome the sensitivity limitations for PS and polyolefins by using e.g. pyrolysis-GC/MS are highlighted.

Quantification of poly(ethylene terephthalate) micro- and nanoparticle contaminants in marine sediments and other environmental matrices.

Microplastics are ubiquitous pollutants in marine and freshwater bodies. Poly(ethylene terephthalate) microfibers (PMFs) are among the main primary microplastics (as-produced polymer microparticles). Released in large amounts in laundry wastewaters, PMFs end up in freshwater and marine sediments due to their high density. PMFs are potentially hazardous pollutants for ecosystems and human health, being a deceiving food source for animal organisms at the base of the food chain (e.g. sediment and water filtrators, including edible shellfish and small crustaceans). This study describes a simple, sensitive and versatile procedure for quantifying the total mass of PET micro- and nano-particles in sediments. The procedure involves aqueous alkaline PET depolymerization with phase transfer catalysis, oxidation and fractionations to remove interfering species and pre-concentrate the terephthalic acid (TPA) monomer, and TPA quantification by reversed-phase HPLC. Recovery of TPA from a model sediment spiked with 800 ppm PET micropowder was 98.2 %, with limits of detection/quantification LOD = 17.2 µg/kg and LOQ = 57.0 µg/kg. Analyses of sandy sediments from a marine beach in Tuscany, Italy, showed contamination in the 370-460 µg/kg range, suggesting that a not negligible fraction of PET microfibers released in surface waters ends up in shore sediments.

New polymer-supported mono- and bis-Cinchona alkaloid derivatives: synthesis and use in asymmetric organocatalyzed reactions.

The straightforward synthesis of polystyrene-supported Chinchona alkaloids and their application in the asymmetric dimerization of ketenes is reported. Six different immobilized derivatives, consisting of three dimeric and two monomeric 9-O ethers, were prepared by "click" anchoring of soluble alkaloid precursors on to azidomethyl resins. The resulting insoluble polymer-bound (IPB) organocatalysts were employed for promoting the dimerization of in-situ generated ketenes. After opening of the ketene dimer intermediates with N,O-dimethylhydroxylamine, valuable Weinreb amides were eventually obtained in good yield (up to 81 %) and excellent enantiomeric purity (up to 96 % ee). All of the IPB catalysts could be recycled effectively without significant loss of activity and enantioselectivity. The extension to other asymmetric transformations (meso-anhydride desymmetrization and α-amination of 2-oxindoles) is also briefly discussed.

Regulation of cardiac fatty acids metabolism in transgenic mice overexpressing bovine GH.

Cardiac energy metabolism depends mainly on fatty acid (FA) oxidation; however, regulation of FA metabolism in acromegalic (Acro) heart is unknown. The aim of the study was to evaluate cardiac expression of key proteins of FA metabolism in young and elder transgenic mice overexpressing bovine GH Acro. Expression of proteins regulating FA entry into the cells, their uptake by mitochondria and beta-oxidation were evaluated by western blot, while FA content by Fourier transform infrared microspectrometry. Regulatory mechanisms of key steps of FA metabolism were also studied. The expression of plasma-membrane FA carriers (fatty acid-binding protein and fatty acid transport protein-1) and acylCoA synthetase was higher in young and lower in elder Acro than in corresponding controls; likewise, expression of cytoplasm to mitochondria-1 (CPT-1), the key enzyme of mitochondrial FA uptake, and that of medium-chain acyl-CoA dehydrogenase and long-chain acyl-CoA dehydrogenase, two regulatory beta-oxidation dehydrogenases, followed a similar pattern. FA content was lower in young and higher in elder Acro than in wild-type, suggesting an increased utilisation in young animals. GH regulated expression of key proteins of FA metabolism through changes in peroxisome proliferator-activated receptor alpha (PPARalpha) expression, which varied accordingly. GH effect was confirmed by treatment of Acro mice with a receptor antagonist, which abolished changes in key proteins of FA metabolism in young Acro. GH increased phosphorylation of AMP-activated protein kinase and anti-acetyl-CoA-carboxylase, two regulatory kinases, leading to lower CPT-1 inhibition by malonyl-CoA, and intervened in regulating PPARalpha expression through the ERK 1/2 pathway. In conclusion, chronic GH excess increased FA metabolism in the young age, whereas its action was overwhelmed in elder ages likely by GH-independent mechanisms, leading to reduced expression of key enzyme of FA metabolism.

Cardiac expression of adenine nucleotide translocase-1 in transgenic mice overexpressing bovine GH.

Heart hypertrophy is a common finding of acromegaly, a syndrome due to GH excess. Impairment of adenine nucleotide translocase-1 (ANT-1) gene, the main mitochondrial ADP/ATP exchanger, leads to cardiac hypertrophy. The aim of the study was to evaluate cardiac expression and the functional role of ANT-1 in 1- to 12-month-old transgenic mice overexpressing bovine GH (acromegalic mice, Acro) and littermate controls (wild-type mice, Wt). GH specificity of protein degree variation was assessed treating Acro with pegvisomant, a GH receptor competitor. Tissue levels of ANT-1, NF-kappaB, ATP, and lactic acid were evaluated by western blot, bioluminescence, and Fourier transform infrared spectroscopy respectively. The degree of ANT-1 expression was higher in 1-month-old Acro than in Wt (47+/-5% OD vs 33+/-4% OD, P<0 01). On the contrary, ANT-1 expression was lower in 3- to 12-month-old Acro than in Wt (P<0 03). Changes in ANT-1 expression were associated with consistent changes of cellular ATP content, increasing at 1 month (P<0 05) and reducing thereafter in Acro when compared with Wt (P<0 04). Treatment with pegvisomant abolished ANT-1 and ATP changes observed in 1- and 3-month-old Acro, thus supporting a GH-dependent mechanism. Reduced ATP generation in hypertrophied hearts of older Acro was associated with increased lactic acid levels suggesting that part of energy was due to glycolysis. Variations in ANT-1 expression were linked to GH through changes in NF-kappaB, the levels of which changed accordingly. In conclusion, 1-month-old acromegalic mice had increased ANT-1 expression and higher degree of ATP production. Long-standing disease was associated with a consistent reduction of ANT-1 and ATP tissue levels, which became GH-independent in older animals. This study demonstrated a direct effect of GH on key proteins involved in energy metabolism of acromegalic hearts.