Types Of Polymers Research Articles

Microplastics in surface seawater of Kongsfjorden, Svalbard, Arctic

Microplastics have now become an emerging contaminant with high concern in the Arctic and Sub-Arctic Region. Here, the Kongsfjorden system in the Arctic has been investigated for abundance, distribution, and characteristic of microplastics in surface seawater. Eighteen samples were collected using an in-situ filtration sampling method, and then analyzed by Fourier-transform infrared spectroscopy. The average abundance of microplastics in surface seawater was 3.6 items m−3, with an abundance range of 0.0—10.0 items m−3. The highest abundance of microplastics was located adjacent to the eddy in Kongsfjorden, where a microplastic accumulation zone might have formed. Microplastics transported by ocean currents and those from local discharges might converge in this zone. Two sampling stations were set up at the wastewater treatment plant outfall, which showed an abundance range of 4.0—6.0 items m−3, slightly higher than the average abundance. Of the six polymer types identified, rayon, polyester and polyamide were the most common composition. Proportions in fiber form in surface water was 84.6 %, and blue (28.2 %) and transparent (25.6 %) were predominant colors. Most microplastics (>90.0 %) were less than 1 mm in the longest dimension. This study provided important baseline data as well as a practical microplastic sampling method for polar marine environments.

Invisible threat to mesopelagic fish: Microplastics and artificial cellulose particles in bigfin lanternfish Symbolophorus californiensis from the Northwest Pacific Ocean

Lanternfishes play an important role in connecting epipelagic and mesopelagic ecosystems. Due to their global distribution, diel vertical migration, and low trophic position, they may be highly susceptible to the ingestion of microplastics (MPs) and artificial cellulose particles (ACs). However, the role of lanternfishes in these emergent pollution research remains underestimated. In this study, we compared the abundance and characteristics of MPs and ACs in the stomach and intestine of bigfin lanternfish (Symbolophorus californiensis) from the Northwest Pacific Ocean. The results showed no difference in the abundance and size of MPs between the stomach (0.28 ± 0.63 items/individual, 103.72–2946.58 μm) and intestine (0.32 ± 0.56 items/individual, 122.03–4398.17 μm). The majority of MPs were fibrous in shape, with blue and transparent being the predominant colors. Polyester (28.2 %) and polyethylene terephthalate (20.5 %) were the most common polymer types. ACs were also primary in the shape of fiber (93.2 %), with transparent being the predominant color. The abundance of ACs in the intestine (0.49 ± 0.83 items/individual) was significantly higher than that in the stomach (0.18 ± 0.43 items/individual), while similar particle sizes were observed. This study provides an important baseline on lanternfishes contamination by MPs and ACs. Understanding this impact of mesopelagic fish is crucial for enhancing our comprehension of the vertical transfer mechanism of these pollutants between epipelagic and mesopelagic ecosystems.

Occurrence and characterization of microplastics in bottled drinking water

Microplastics (MPs) have been identified in diverse settings, including drinking water, freshwater, food, air, and marine environments. This study employed stereomicroscopic and µ-Raman techniques to analyze water samples from ten widely consumed bottled water brands, aiming to detect and characterize MPs. Additionally, the oral consumption of MPs per capita was estimated. The average abundance of MPs ranged from 9 ± 1.00 MPs/L to 3 ± 1.73 MPs/L across all brands. Various MPs shapes were observed, including fibers, fragments, films, and pellets, with fibers being predominant (58.928%). MPs were categorized by color into five groups (red, blue, black, yellow, and transparent), with red comprising approximately 35.714% of the total count. All identified MPs were less than 500 µm in size. µ-Raman analysis validated the presence of eight different polymer types in the samples, namely Polypropylene (PP) (37.5%), Polymethyl methacrylate (PMMA) (3.571%), polystyrene (PS) (33.928%), polycarbonate (PC) (3.571%), polybutylene1 (PB1) (14.2%), Isotactic polypropylene (iPP) (7.142), Nylone 6-α polymorph (αNY6) (5.357%), and polyvinyl alcohol (PVOH) (1.785%). The estimated daily intake of MPs per person was determined to be 0.42 MPs, translating to an annual intake of 153.3 MPs per person. The origin of MPs in bottled water was likely attributed to both raw water sources and packaging materials, underscoring the need for further investigation. Given the potential health implications of human exposure to drinking water MPs, careful consideration should be given to the use of plastic packaging for potable water.

Occurrence of microplastics in the gastrointestinal tracts of four most consumed fish species in Giresun, the Southeastern Black Sea.

Microplastic studies investigating concentrations in water are numerous, but the majority of microplastics settle and are retained in sediment, and higher concentrations are regularly reported in sediments. Thus, MPs accumulation may be more threatening to benthic fish living in sediments than to pelagic fish. The presence, abundance and diversity of microplastics were investigated by collecting samples from two pelagic, European anchovy, and horse mackerel and two benthic fish species, red mullet, and whiting that are popularly consumed in Giresun province of Türkiye, located on the southern coast of the Black Sea. Visual classification and chemical compositions of microplastics was performed using a light microscope and ATR-FTIR spectrophotometry, consecutively. The overall incidence and mean microplastics abundance in sampled fishes were 17 and 1.7 ± 0.18 MP fish-1, respectively. MPs were within the range of 0.026-5mm in size. In most of the cases, the MP was black in color with 41%. With the rates of 56%, polypropylene was the predominant polymer type. The most dominant MP type was identified as fiber followed by fragments and pellets. The relationship between MP amounts in fish and Fulton condition factor was not strong enough to establish a cause-effect relationship.

Distinct microbial community structures formed on the biofilms of PLA and PP, influenced by physicochemical factors of sediment and polymer types in a 60-day indoor study

Microplastics (MPs) are colonized by biofilm-forming microbes. Biodegradable plastics, popular replacements for traditional plastics, still have unknown biofilm formation characteristics. We conducted a 60-day indoor experiment, where sediment was exposed to traditional MPs (polypropylene, PP), biodegradable MPs (polylactic acid, PLA), and glass beads (GLASS). The microbial communities in the MPs-biofilm were analyzed using high-throughput sequencing. Results indicated that Proteobacteria was the dominant phylum on all substrates, followed by Actinobacteria, and Firmicutes. At the genus level, the majority of microorganisms colonizing PP possessed nitrification and denitrification capabilities, while the dominant bacteria on PLA were capable of degrading lignin, cellulose and carbon metabolism. The genus Sphingomonas, a promising bacteria capable of degrading biodegradable microplastics, was particularly discovered on the PLA biofilm, meanwhile, bacterial colonization of PLA indirectly increased the potential for human transmission of pathogens. Redundancy analysis revealed that the pH and moisture significantly affected the bacterial communities. Pearson correlation heatmap indicated that the abundance of the majority of dominant bacterial genera of two MPs biofilms is negatively correlated with the physicochemical parameters of sediment (pH, moisture, TN, TP), except for salinity. The microbial communities associated with PP and PLA exhibited distinct differences caused by the combined effects of changes in physicochemical properties of sediment and different material substrates. This study provides further evidence of the significant selective features exhibited by microbial colonization on these two MPs when exposed to the same source community, offering insights into the exploration of promising bacteria for MPs degradation.

Stable Persistent Room-Temperature Phosphorescent Hydrogels Based on Ionically Crosslinked Nonaromatic Carboxylate Polymers.

Developing pure organic room-temperature phosphorescent (RTP) hydrogels is important for expanding the practical applications of phosphorescent materials. However, most of the reported RTP hydrogels containing aromatic phosphors suffer from short phosphorescent lifetimes, unstable underwater RTP emissions, and complex preparation processes. Herein, novel nonaromatic RTP hydrogels are prepared by using two types of non-traditional luminescent polymers, sodium alginate and a polymeric carboxylate, which are not RTP emissive or very weakly emissive in aqueous environments. The prepared hydrogels exhibit the following features: I) color-tunable RTP emissions with ultra-long lifetimes up to 451.1ms, II) excellent anti-swelling properties and stable persistent RTP emission even after being immersed in deionized water for months, III) efficient and large-scale preparation of hydrogel fibers by wet spinning technique. Experiment results and theoretical calculations show that the stable and long-lifetime RTP emissions of the hydrogels originate from the introduction of more nonconventional chromophores which are strongly crosslinked with ionic bonding between carboxylate groups and calcium ions and enhanced through-space interactions between them. This work provides a reliable strategy for designing nonaromatic hydrogels with stable and persistent RTP.

Characteristics, Abundance and Polymer Type of Microplastics in Anadara granosa (Blood Clam) from Coastal Area of Palopo City

Plastic waste in marine waters will undergo a degradation process that breaks down large plastic pieces into smaller particles called microplastics. The abundance of microplastics, caused by their small size (<5mm) can be easily indirectly consumed by aquatic animals. Anadara granosa is one of the bivalves that is quite vulnerable to microplastic contamination because it has the nature of a filter feeder which means it can sift particles and organic matter around it. The purpose of this study was to determine the characteristics, abundance, and types of microplastic polymers in blood clams (A. granosa). The results of microplastic observations made on 60 blood clams were 153 microplastic particles identified from 47 individuals (78%) of contaminated blood clams with an average microplastic abundance of 0.591 ± 0.083 item/gr. Fiber-type microplastics are the most dominant form found and blue is the most dominant color found in the sample. Based on the average abundance of microplastics in Anadara granosa in the coastal area of Palopo City, it is lower than several studies that have been conducted previously. Fourier Transform-Infra Red was conducted to determine the type of polymer in microplastics. Three types of polymers were found in the Anadara granosa samples polyethylene terephthalate (PET), polystyrene, and polyester. The three types of polymers have effects on human health such as respiratory problems, skin irritation, and genotoxicity. Action is needed to prevent microplastic pollution in Palopo City’s rivers before microplastic pollution becomes more severe in the future.

Spatiotemporal variations and the ecological risks of microplastics in the watersheds of China: Implying the impacts of the COVID-19 pandemic

China is not only the first reported place of the COVID-19 pandemic but also is the biggest microplastic emitter in the world. Nevertheless, the impact of the COVID-19 pandemic on microplastic pollution in the watersheds of China remains poorly understood. To address this, the present study conducted a data mining and multivariate statistical analysis based on 8898 microplastic samples from 23 Chinese watershed systems before and during the COVID-19 pandemic. The results showed that the COVID-19 pandemic extensively affected the abundance, colors, shapes, polymer types, and particle sizes of microplastic in Chinese watershed systems. Before and during the COVID-19 pandemic, 77.27 % of the Chinese watershed systems observed increased microplastic abundance. Moreover, the COVID-19 pandemic itself, natural conditions (such as altitude and weather), and anthropogenic factors (such as civil aviation throughput) are highly intertwined, jointly impacting the microplastic in the watersheds of China. From the perspective of ecological risks, the COVID-19 pandemic was more likely to aggravate the microplastic pollution in the middle and down reaches of the Yangtze River Watersheds. Overall, whether before or during the COVID-19 pandemic, the main watershed systems of China still stayed at a high pollution level, which rang the alarm bell that watershed systems of China had been at serious ecological risk accused of microplastic contamination.

Microplastic evidence assessment from water and sediment sampling in a shallow tropical lake.

Microplastics (MPs) severely threaten inland waterbodies due to the direct impact of human activities. In the present study, spatial and temporal patterns of MPs in a shallow tropical lake were assessed, describing their size, morphology, and polymer types. Water and sediment samples were collected from Lake Chapala during three seasons, and MPs were quantified with a stereomicroscope. The structure, elemental composition, and polymeric composition were determined via environmental scanning electron microscopy and Fourier transform infrared spectroscopy. The highest average concentration of microplastics in Lake Chapala was detected during the low-water period in April 2022 (2.35 items/L), exceeding the July 2022 rainy season concentration (1.8 items/L) by 0.25 items/L, and sediment concentrations were also higher in April 2022 (219 items/kg) compared to July 2022 (210 items/kg). This study highlights the significant pollution of Lake Chapala with microplastics, emphasizing the need for urgent measures to manage plastic waste and mitigate its environmental impact on aquatic ecosystems. PRACTITIONER POINTS: Microplastic contamination was evaluated in Lake Chapala. The distribution profiles of microplastics were different in each area. Heavy metals osmium, tellurium, and rhodium were found associated with the PMs. Polymers were found in this study.

Microplastic pollution in aquafeed of diverse aquaculture animals

Microplastics have emerged as pervasive contaminants, and determining their occurrence in aquafeed is key for evaluating their risks to farmed animals and, by extension, humans. However, knowledge about microplastic in aquafeed is still limited. Herein, we determined microplastic characteristics in aquafeed for five important aquaculture animals with different feeding habits. Aquafeed samples were collected for spotted sea bass, shrimp, grass carp, Tilapia, and frogs from main companies in China. The samples were digested using chemical digestion, and the residuals were subjected to a density separation. Microplastics were identified under the microscope and characterized by their shape, color, size, and polymer type. The results showed that microplastics are highly abundant in the feed of frogs, followed by spotted sea bass, Tilapia, grass carp, and shrimp. We found that feed size contributes to the total microplastic abundance in the feed. Further, microplastics were mainly in microfiber form, and the dominant polymer type was propylene, suggesting that packaging and processing are the main sources of pollution. Additionally, the most abundant size of microplastics was 100–1000 μm. Calculating microplastic ingestion risk, the spotted sea bass had the greatest recorded risk of microplastic ingestion, followed by grass carp, frogs, Tilapia, and shrimp. This study lays a foundational step toward understanding microplastic effects on aquaculture animals and calls for further environmentally relevant laboratory experiments to assess the risk of microplastic ingestion on animals and potential transfer to humans.

Curcumin- and quercetin-functionalized polypropylenemembranes as active food packaging material.

A wide range of active agents, synthetic and natural agents such as essential oils, chitosan and polyphneols consisting of curcumin, gallic acid, anthocyanins, and catechins have been used in order to develop antimicrobial packaging systems, and among them, natural polyphenolic compounds, specially curcumin (Cur) has great potential due to effective biological activities in developing food packaging material. Quercetin (Quer) is also the mostly studied flavonol as a color-changing indicator in the food industry and has been already developed as a realistic alternative for smart and active food packaging. The reason for choosing these two polyphenolic compounds is that they simultaneously possess many beneficial properties such as antioxidant, antibacterial, antiviral, antitumoral, and anti-inflammatory effects. Additionally, the main objective of the study is to combine polypropylene (PP), which is the most preferred and cost-effective polymer in the packaging industry, with these active ingredients, rather than using more expensive polymer types. In this context, PP-Quer or PP-Cur membranes, which are new experiences based on these literatures were chemically characterized by Fourier transform infrared spectroscopy, and the surface morphology of these composite membranes was characterized by scanning electron microscopy. The antibacterial response against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria species was investigated. Furthermore, the reactive oxygen species generation and anticancer activity of these composite membranes using human colorectal adenocarcinoma (HT-29) were observed. We proposed that PP-Quer or PP-Cur composite membranes can be a potential candidate as active packaging material in the food industry.

Microplastic fate in a chronosequence of biosolid‐amended agricultural soil in Southern Ontario, Canada

AbstractMunicipally sourced biosolids are commonly used as cost‐effective fertilizers, diverting material from landfills and contributing to the circular economy. However, biosolids contain high concentrations of microplastics (MPs), which are emerging contaminants of concern due to their ubiquity in the environment. Despite this, there is a lack of environmentally relevant field studies. In 2022, composite topsoil samples (0–15 cm depth) were collected from seven agricultural fields in Southern Ontario, Canada, representing a chronosequence of biosolid applications ranging from 1 to 9 years since amendment and a control (untreated) field. MP particles down to 20 μm in size were extracted by density separation, enumerated, characterized by stereomicroscope and polymers identified using attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy. Here, we report on the characteristics, abundance and polymer type of MP particles in the study area to assess their fate in biosolid‐amended soils. The average MP concentration among fields was 6.87 ± 1.47 MP g−1 (3.43 ± 0.74 mg MP kg−1). Additionally, the MP soil pool increased with repeated applications of biosolids. The dewatered biosolid plastic content of 8816 ± 1809 MP g−1 dry weight (11.6 ± 17.5 g MP kg−1 dry weight) was used to estimate a mean MP loading of 94.5 ± 10.9 kg ha−1 to each field per application, suggesting that 7% of the MP soil pool persisted over time. Quantifying the MP pool in biosolid‐amended agricultural soil will inform evidence‐based plastic policy changes in our global effort to understand and reduce plastic pollution.

Source identification, characteristics, and spatial distribution of airborne microplastic deposition in Lahore City, Pakistan.

A large volume of atmospheric microplastics (MPs) has been observed worldwide and is considered an emerging global environmental issue. Nevertheless, no significant assessment of the atmospheric deposition of MPs in Pakistan has been reported yet. The present study was designed to highlight the source, type, and spatial distribution of MPs in atmospheric fallout in Lahore, Pakistan. A total of 23 sites were sampled in Lahore with a heterogeneous background of human activities. All samples were collected in a box with a one-foot depth fitted with a steel tray of 0.1 m2 at the bottom. Fenton's reagent and hydrogen peroxide were used to remove organic matter, and sodium chloride for density separation, while the MPs were quantified through a stereomicroscope, and polymers were identified through ATR-FTIR spectroscopy. The highest deposition rate (particles/m2/day) was observed at Badami Bagh, i.e., 6819, followed by Mall Road 4414, and Chung 4263, while the lowest was in Sabzazaar (i.e., 524) and Township (1047) with an average deposition rate of 2340 ± 1392. Among the MPs, the major portion was fiber, i.e., 96%, while fragment was 1.9%, sheets 0.78%, foams 1.12%, beads 0.04%, and other MPs 0.06%. At all sampling sites, 20 different types of polymers were identified with different percentages, of which polyester fibers were predominant with an abundance of 96.09% associated with clothes and textiles. A high frequency of MPs was found in populated areas with dense traffic, plastic wastes, household plastic materials, and mismanagement of wastes, which accelerates the atmospheric deposition of airborne microplastics. Evaluation and characterization of MP help assess health and environmental impacts, cleanup efforts, and guiding regulations. It also provides valuable information for waste management innovation to reduce plastic pollution.

Evaluating the sources of microplastic contamination and quantifying its abundance in the Balu River, Dhaka, Bangladesh.

Microplastics (MPs) are prevalent environmental pollutants due to their durable composition, extensive use, and improper disposal. Despite their widespread presence, rivers have received less attention in microplastic research than other water bodies. This study focused on investigating the origins, prevalence, spatial distribution, and physicochemical characteristics of microplastics in the surface waters of the Balu River, located in Dhaka, Bangladesh. Surface water samples were collected at six sampling sites of Balu River (each about 1-5km apart) adjacent to the footwear industry, jute factory, textile mill, paper mill, agro and beverage factory, and cement plant. The study found that the average concentration of microplastics in the sampled water bodies was 102.5 ± 12.83 (items/l). Samples near the textile mill had the highest microplastic abundance (122 ± 18 items/l), while the cement plant had the lowest (58.5 ± 8 items/l). Analysis using a stereomicroscope revealed that fibers (29%), microplastics smaller than 100µm (45%), and transparent microplastics (19%) were the most prevalent types observed in terms of shape, size, and color, respectively. Furthermore, scanning electron microscopy (SEM) observation suggested the potential for additional degradation of these microplastics into smaller particles, potentially reaching the nanoplastic scale. Additionally, Fourier transform infrared (FTIR) analysis identified 07 distinct polymer types among the microplastics: nylon (24%), polyvinyl chloride (19%), high-density polyethylene (17%), low-density polyethylene (14%), polystyrene (12%), polypropylene (7%), and nitrile (7%). The findings of this study serve as a crucial indicator of microplastic contamination, providing valuable insights into the sources and magnitude of microplastic pollution within the significant freshwater ecosystem of Balu River, Bangladesh, particularly focusing on its river systems.

Application of Hydrophilic Polymers to the Preparation of Prolonged-Release Minitablets with Bromhexine Hydrochloride and Bisoprolol Fumarate.

Minitablets have been extensively studied in recent years as a convenient pediatric form because they allow successful administration even in very young children. Their advantages include easy dose adjustment by multiplication of single units as well as the possibility of drug release modification by coating or forming matrix systems. The aim of this study was to demonstrate the possibility of the formulation of prolonged-release minitablets with bromhexine hydrochloride (BHX) and bisoprolol fumarate (BFM) dedicated to pediatric patients. Minitablets with 3 mm diameter and 15 mg mass, containing 1 mg of active substance in 1 unit, were prepared by direct compression with hydroxypropyl methylcellulose (HPMC) of different grades, methylcellulose, sodium alginate, or polyvinyl alcohol (PVA) as a sustained-release polymer. Different amounts of polymers and different compression forces were evaluated. Analysis of minitablets included their uniformity, hardness, and dissolution tests. The kinetics of drug substance release were analyzed with dedicated software. The prepared minitablets met the pharmacopeial requirements with respect to the uniformity of mass and content. The compressibility of BFM was significantly better than that of BHX, yet all minitablets had good mechanical properties. Dissolution studies showed a strong relationship between the type of polymer and its amount in the mass of a tablet and the dissolution rate. Prolonged release of up to 8 h was achieved when HPMC of 4000 cP viscosity was used in the amount of 30% to 80%. Sodium alginate in the amount of 50% was also effective in prolonging dissolution, but PVA was much less effective. Studies on the release kinetics showed that dissolution from prolonged-release minitablets with BHX fit the best to Hopfenberg or Hixson-Crowell models, while in the case of BFM, the best fit was found for Hopfenberg or Korsmeyer-Peppas models.

Recent Advances in Fluorescent Polyimides.

Polyimide (PI) refers to a type of high-performance polymer containing imide rings in the main chain, which has been widely used in fields of aerospace, microelectronic and photonic devices, gas separation technology, and so on. However, traditional aromatic PIs are, in general, the inefficient fluorescence or even no fluorescence, due to the strong inter- and intramolecular charge transfer (CT) interactions causing unavoidable fluorescence quenching, which greatly restricts their applications as light-emitting functional layers in the fabrication of organic light-emitting diode (OLED) devices. As such, the development of fluorescent PIs with high fluorescence quantum efficiency for their application fields in the OLED is an important research direction in the near future. In this review, we provide a comprehensive overview of fluorescent PIs as well as the methods to improve the fluorescence quantum efficiency of PIs. It is anticipated that this review will serve as a valuable reference and offer guidance for the design and development of fluorescent PIs with high fluorescence quantum efficiency, ultimately fostering further progress in OLED research.

Formulation and evaluation of melatonin as fast dissolving oral strips using combined polymers

Background and objective: Fast-dissolving oral thin film (FDOF) is a novel and most advanced form of solid dosage form that dissolves or disintegrates in 1 minute when put in the mouth without water or chewing. Pre-gastric absorption of FODFs from the mouth, pharynx, and esophagus as saliva flows down into the stomach would improve the therapeutic benefit of the drug as oral films disintegrated in the mouth. The study is designed and purposed to use most water soluble, best type and concentration of polymers to be selected for use in combination to formulate melatonin oral thin films. Different types of synthetic water soluble polymers were utilized the preparation of films (hydroxypropyl methyl cellulose HPMC15M, sodium carboxy methyl cellulose NACMC). Methods: Solvent casting method was performed for preparation of twelve placebo films at the beginning, to obtain and select suitable polymer type and concentration for use in combination to be formulated for drug loading. The films were evaluated for their characteristics like mechanical properties (thickness and folding endurance), surface pH and disintegration time. Percentage of release and assay of melatonin was taken. Comparison studies were performed on melatonin films from this study with melatonin oral disintegrating tablets release profiles. Best batch could be selected. Drug-excipient compatibility carried out as pre formulation study to see whether there is interaction between the drug and excipients used. Results: Results from FT-IR showed no interaction between melatonin and polymers used, the prepared formulations were clear, transparent, non-sticky and easily removed from the plate surface with the thickness ranging from (0.04-0.07) mm depending on the polymer concentration. The times required for the films to disintegrate was ranging from 21-26 seconds, and the majority of melatonin was released within first 2 minutes within the dosage form. Conclusion: Melatonin can be formulated as fast dissolving oral films using combination of water-soluble polymers by solvent casting method to obtain ease of administration without using water during administration, fast onset of action resulted from rapid disintegration.

Controllable Synthesis of Chain Center Dye-Labeled Star Polymers for Quantitative Examination of Interchain Conformation by Time-Resolved Fluorescence Resonance Energy Transfer.

Using a "core-first" approach with atom transfer radical polymerization, fluorescent center-functional star polymers of equivalent molecular weight but with varying numbers of arms (di-, tri-, and tetra-arm) were prepared. The sensitivity of fluorescence, combined with a dye-labeling technique introducing a fluorescent donor (carbazole) and an acceptor (anthracene) at the center of poly(methyl methacrylate) (PMMA) chains, enabled the application of time-resolved fluorescence resonance energy transfer to obtain quantitative insights into the conformation of the star polymer chains in the film state. When the results of star-branched polymers were compared with those of linear polymers of identical type and molecular weight, the impact of branching on polymer behavior was isolated for examination. Although the star topology does not alter the average intercoil distance, it affects the distance dispersity. Star polymers with higher arm numbers display decreased dispersity from distance due to reduced intermolecular aggregation at their geometric centers. This study presents the first spectroscopic evidence regarding the distribution of geometric centers in star polymers, offering a physical understanding of chain interpenetration and entanglement within star polymers.

Assessment of microplastics in human stool: A pilot study investigating the potential impact of diet-associated scenarios on oral microplastics exposure

As emerging contaminants microplastic particles have become of particular relevance as they are widely present in the environment and of potential concern to human health. Humans are exposed through different routes, with oral intake and inhalation being the most significant. Dietary intake substantially contributes to oral exposure, although data is still lacking. This first-of-its-kind pilot study investigates the influence of different plastic use and food consumption scenarios (normal, low, high) on microplastic content in stool reflecting oral intake by performing an intervention study with fifteen volunteers. Stool samples were analyzed for ten different plastic types in three size fractions including 5–50 μm (qualitative), 50–500 μm and 500–5000 μm (quantitative). In all samples, microplastic particles were detected with median concentrations up to 3.5 particles/g stool in the size fraction 50–500 μm. Polyethylene was the most frequently detected polymer type. The different scenarios did not result in a consistent pattern of microplastics, however, the use of plastics for food packaging and preparation, and the consumption of highly processed food were statistically significantly associated with microplastics content in stool. These results provide initial findings that contribute to filling current knowledge gaps and pave the way for further research.

Vertical Flux of Microplastics in the Deep Subtropical Pacific Ocean: Moored Sediment-Trap Observations within the Kuroshio Extension Recirculation Gyre.

The Kuroshio Extension recirculation gyre in the western North Pacific is an accumulation site of plastic litter transported by the Kuroshio Current. A sediment trap was moored at a depth of 4900 m at Station KEO within the Kuroshio Extension recirculation gyre, and the vertical flux of microplastics in sinking particles of size <1 mm was observed. Forty-one sediment-trap samples collected from July 1, 2014, to October 2, 2016, were analyzed with a micro-Fourier transform infrared spectrometer and microplastics were detected in all samples. Seventeen polymer types were identified, and 90% of the microplastics were less than 100 μm in size. Microplastic sinking was driven by the action of the biological pump, which was in turn driven by seasonal variations in solar radiation and increased surface primary production typical of the spring season. Microplastic mass flux varied from 4.5 × 10-3 to 0.38 mg m-2 day-1 during the sampling period, with a mean and standard deviation of 0.054 ± 0.075 mg m-2 day-1. Extrapolating the annual microplastic mass flux at Station KEO to the entire Kuroshio Extension recirculation gyre, it is estimated that 0.028 million metric tons of microplastics are transported annually to 4900 m depth in this area.