New plastic formations in the Anthropocene

Plastic pollution is one of the major challenges in the Anthropocene. Upon reaching the marine environment, plastic debris is subject to anthropogenic and environmental conditions that result in novel items that vary in composition, physical and chemical characteristics. Here, we reviewed and discussed the potential fate and threat to the environment of four recently described plastic formations: Plastiglomerates, pyroplastics, plasticrusts, and anthropoquinas. The threats identified were mostly related to the release of toxic chemicals and plastic ingestion. Transportation of alien invasive species or microbial pathogens and fragmentation of larger plastics into microplastics (<5 mm), potentially reaching marine trophic webs, are suspected as potential impacts based on the characteristics of these plastic formations. Some plastic forms may persist in the environment and voyage across the ocean, while others are denser and less likely to enter the plastic cycle or interact with biota. In the latter case, plastics are expected to become buried in the sediment and incorporate into the geological record. It is necessary to establish sampling protocols or standards that are specific to each plastic formation and start reporting the occurrence of these new plastic categories as such to avoid underestimating plastic pollution in marine environments. It is suggested that monitoring plans include these categories and identify potential sources. Further research must focus on investigating whether the suspected impacts are a matter of concern. In this sense, we have suggested research questions to address the knowledge gaps and have a better understanding of the impacts and distribution of the new plastic forms.

First record of an Anthropocene marker plastiglomerate in Andaman Island, India

One of the most significant environmental issues confronting our world is plastic trash, which is of particular concern to the marine environment. The sedimentary record of the planet may likely one day contain a horizon of plastic that can be potentially identified as an Anthropocene marker. Here we report the presence of 'plastiglomerate' from coastal habitats located in the Aves Island, Andaman Sea, India. This novel form of plastic pollution forms with the incineration of plastic litter in the environment and then mixing of organic/inorganic composite materials in the molten plastic matrix. The plastic pollutants were collected from the Aves Island beach during marine litter surveys. Micro-Raman (μ-Raman) spectroscopy was used to evaluate and confirm all putative plastic forms. Plastiglomerates were made of a polyethylene (PE) and polyvinyl chloride (PVC) matrix with inclusions of rock and sand. Therefore, our research offers new insight into the intricate process of plastiglomerates formation.

Conglomerate ring and tract-like enhancement lesions: Neuroimaging in Listeria monocytogenes brain abscess

This report aims to describe a characteristic neuroimaging of Listeria monocytogenes brain abscess in predisposed patients. A 56-year-old man presented with fever and headache for 3 weeks. Cerebrospinal fluid (CSF) revealed pleocytosis with lymphocytosis, high protein, and low glucose. Both hemoculture and CSF culture yielded L monocytogenes. Another case is a 23-year-old woman with systemic lupus erythematosus, who presented with fever, headache and left hemiparesis. CSF showed pleocytosis with polymorphonuclear cells predominance and low glucose. Hemoculture positive for L monocytogenes. Their MRI brain revealed conglomerate ring and tract-like enhancement lesions at the right parietotemporal lobe. The patients were diagnosed with L monocytogenes brain abscess. They received a high dose of ceftriaxone and ampicillin for 6 weeks. The clinical and MRI at the end of treatment was a substantial improvement. Our information can help the physician concern about this pathogen in patients who presented with brain abscess and had these MRI findings.

Identification and proportion of the enantiomers of the antihypertensive drug chlortalidone in its Form II by high quality single-crystal X-ray diffraction data

Chlortalidone (CTD) is a diuretic drug largely used as part of antihypertensive therapies. It is marketed as an equimolar mixture of its enantiomers in the racemic crystal phase named Form I, despite of the higher aqueous solubility of another crystal form. The latter, named Form II, was thought to contain both enantiomers as a racemic conglomerate, i.e., in the form of a mixture of crystals, half of which consists solely of the (R)-enantiomer, the other half the (S)-enantiomer. The occurrence of both enantiomers in individual crystals of CTD Form II was demonstrated in this study. Spontaneous resolution does really occur upon crystallization, as presumed previously even without physical evidence of the (S)-enantiomer. Both (R) and (S)-enantiomers were successfully identified as two domains of a twinned by inversion single crystal of CTD Form II. A reliable Flack parameter of 0.14(4) allowed to determine the proportion of the enantiomers in the crystal, which is formed with 86% of the (R)-enantiomer and 14% of the (S)-enantiomer.

Plastic Silica Conglomerate with an Extremophile Microbial Matrix in a Hot-Water Stream Paleoenvironment

A new and unusual type of fossil, siliceous hot-spring deposit (sinter)-comprising monomictic, quartzose conglomerate encrusted with silicified microbial laminates-has been recognized in distal portions of Jurassic and Miocene paleo-geothermal fields of South and North America, respectively. The siliceous clasts are inferred to have originated as conduit-delivered hydrothermal silica gel, owing to their general plastic morphologies, which were then locally reworked and redistributed in geothermally influenced stream paleoenvironments. Today, hot-spring-fed streams and creeks, in places with silica-armored pavements, host microbial mats coating streambeds and/or growing over, and silicifying at, stream air-water interfaces, for example, in Yellowstone National Park (USA) and Waimangu Volcanic Valley (New Zealand). However, the modern deposits do not contain the plastically deformed silica cobbles evident in Mesozoic and Cenozoic examples described herein. Moreover, the fossil microbial laminates of this study are relatively dense and strongly coat the silica cobbles, suggesting the mats stabilized the clasts under fully submerged and hot, high-energy conditions. Thus, this new sinter facies, typically found a few kilometers from main spring-vent areas, is a perhaps unexpected extreme environment in which life took hold in hydrothermal-fluvial settings of the past, and may serve as an additional target in the search for fossil biosignatures of early Earth and possibly Mars.

(Co-)amorphization of enantiomers - Investigation of the amorphization process, the physical stability and the dissolution behavior

A novel approach for improvement of the aqueous solubility of poorly water soluble compounds applying co-amorphous systems was investigated by application of the enantiomers of the chiral amino acid tryptophan (TRP) as the model system. (Co-)amorphization of various forms of crystalline TRP was achieved by ball milling. Solid state analysis demonstrated significant differences in the amorphization tendency and physical stability between the two TRP enantiomers alone, the TRP racemate and an equimolar physical mixture of D- and L-TRP (TRP conglomerate). Ball milling for 6 h was required to obtain fully amorphous plain D- and L-TRP, whereas the TRP racemate and the TRP conglomerate were transformed into their amorphous forms already within 90 and 60 min of ball milling, respectively. Physical stability of the co-amorphous TRP conglomerate was observed for up to 60 d at ambient conditions as well as 40 °C/0 % RH. In contrast, the amorphous TRP racemate showed a reduced physical stability under ambient conditions. Interestingly, the intrinsic dissolution rates of the amorphous TRP conglomerate and racemate were not higher than those of the respective crystalline forms. In conclusion, applying two enantiomers of a chiral compound may be a promising approach for fast amorphization of an API and for improving the physical stability of the resulting amorphous form.