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1.
Waste Manag ; 125: 49-57, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33676200

RESUMO

Opaque PET (Polyethylene terephthalate) was recently introduced as a dairy packaging, mainly for milk bottles. Opaque PET, obtained as PET filled with mineral nanoparticles, allows for a reduction of bottles' thickness, thus a cost reduction for industrials. For this reason, the use of opaque PET is steadily increasing. However, its recyclability is nowadays an issue: although the recycling channels are well established for transparent PET, the presence of opaque PET in the household wastes weakens the existing recycling channels. Besides, many initiatives are launched in Europe to turn wastes into resources, as one key to a more circular economy. One of the biggest challenges is an efficient sorting of the plastic solid wastes since the PET is not miscible with other plastics such as polypropylene (PP) from the bottle caps and polyethylene (PE) from the other milk bottles. In this work, the mechanical properties of uncompatibilized blends of opaque PET (rPET-O) with recycled polypropylene (rPP) have been studied; both are collected from household wastes. The tensile properties and the fatigue life of rPP, monitored by in-situ digital image correlation and in-situ infrared thermography, are increased by the incorporation of rPET-O. rPET-O/rPP blends may be substituted to rPP for similar applications, with no need to sort the caps from the bottles. Thus, as a concept, the incorporation of opaque PET into the PP recycling sector may be a new route to absorb some of the growing amounts of opaque PET.


Assuntos
Plásticos , Polipropilenos , Animais , Europa (Continente) , Fadiga , Leite , Polietilenotereftalatos , Reciclagem
2.
Food Chem ; 351: 129284, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-33640773

RESUMO

Coating damage destroys the integrity features critical for maintaining the modified atmosphere inside the fruit. In this study, we developed a self-healing edible coating that maintains its barrier properties for extending the shelf life of strawberries. The coating was fabricated via the layer-by-layer assembly of chitosan (CS) and sodium alginate (SA). (SA/CS)3 formed by three assembly cycles could completely heal the visibly damaged area by treating water. The mechanical properties and the water and oxygen rates of the healed coating were 97%, 63%, and 95%, respectively, of the intact coating. (SA/CS)3 coating effectively delayed strawberry deterioration. Moreover, the coating reduced the impact of coating damage on strawberries by restoring the coating barrier properties. The present findings have important implications for solving the reduction in freshness caused by coating damage.


Assuntos
Filmes Comestíveis , Conservação de Alimentos/métodos , Alginatos/química , Quitosana/química , Qualidade dos Alimentos , Fragaria/química , Fragaria/metabolismo , Frutas/química , Frutas/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Oxigênio/química , Polietilenotereftalatos/química , Resistência à Tração , Água/química
3.
Cochrane Database Syst Rev ; 2: CD000071, 2021 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-33598915

RESUMO

BACKGROUND: Extracranial carotid artery stenosis is the major cause of stroke, which can lead to disability and mortality. Carotid endarterectomy (CEA) with carotid patch angioplasty is the most popular technique for reducing the risk of stroke. Patch material may be made from an autologous vein, bovine pericardium, or synthetic material including polytetrafluoroethylene (PTFE), Dacron, polyurethane, and polyester. This is an update of a review that was first published in 1996 and was last updated in 2010. OBJECTIVES: To assess the safety and efficacy of different types of patch materials used in carotid patch angioplasty. The primary hypothesis was that a synthetic material was associated with lower risk of patch rupture versus venous patches, but that venous patches were associated with lower risk of perioperative stroke and early or late infection, or both. SEARCH METHODS: We searched the Cochrane Stroke Group trials register (last searched 25 May 2020); the Cochrane Central Register of Controlled Trials (CENTRAL; 2020, Issue 4), in the Cochrane Library; MEDLINE (1966 to 25 May 2020); Embase (1980 to 25 May 2020); the Index to Scientific and Technical Proceedings (1980 to 2019); the Web of Science Core Collection; ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) portal. We handsearched relevant journals and conference proceedings, checked reference lists, and contacted experts in the field. SELECTION CRITERIA: Randomised and quasi-randomised trials (RCTs) comparing one type of carotid patch with another for CEA. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed eligibility, risk of bias, and trial quality; extracted data; and determined the quality of evidence using the GRADE approach. Outcomes, for example, perioperative ipsilateral stroke and long-term ipsilateral stroke (at least one year), were collected and analysed. MAIN RESULTS: We included 14 trials involving a total of 2278 CEAs with patch closure operations: seven trials compared vein closure with PTFE closure, five compared Dacron grafts with other synthetic materials, and two compared bovine pericardium with other synthetic materials. In most trials, a patient could be randomised twice and could have each carotid artery randomised to different treatment groups. Synthetic patch compared with vein patch angioplasty Vein patch may have little to no difference in effect on perioperative ipsilateral stroke between synthetic versus vein materials, but the evidence is very uncertain (odds ratio (OR) 2.05, 95% confidence interval (CI) 0.66 to 6.38; 5 studies, 797 participants; very low-quality evidence). Vein patch may have little to no difference in effect on long-term ipsilateral stroke between synthetic versus vein materials, but the evidence is very uncertain (OR 1.45, 95% CI 0.69 to 3.07; P = 0.33; 4 studies, 776 participants; very low-quality evidence). Vein patch may increase pseudoaneurysm formation when compared with synthetic patch, but the evidence is very uncertain (OR 0.09, 95% CI 0.02 to 0.49; 4 studies, 776 participants; very low-quality evidence). However, the numbers involved were small. Dacron patch compared with other synthetic patch angioplasty Dacron versus PTFE patch materials  PTFE patch may reduce the risk of perioperative ipsilateral stroke (OR 3.35, 95% CI 0.19 to 59.06; 2 studies, 400 participants; very low-quality evidence). PTFE patch may reduce the risk of long-term ipsilateral stroke (OR 1.52, 95% CI 0.25 to 9.27; 1 study, 200 participants; very low-quality evidence). Dacron may result in an increase in perioperative combined stroke and transient ischaemic attack (TIA) (OR 4.41 95% CI 1.20 to 16.14; 1 study, 200 participants; low-quality evidence) when compared with PTFE. Early arterial re-stenosis or occlusion (within 30 days) was also higher for Dacron patches. During follow-up for longer than one year, more 'any strokes' (OR 10.58, 95% CI 1.34 to 83.43; 2 studies, 304 participants; low-quality evidence) and stroke/death (OR 6.06, 95% CI 1.31 to 28.07; 1 study, 200 participants; low-quality evidence) were reported with Dacron patch closure, although numbers of outcome events were small. Dacron patch may increase the risk of re-stenosis when compared with other synthetic materials (especially with PTFE), but the evidence is very uncertain (OR 3.73, 95% CI 0.71 to 19.65; 3 studies, 490 participants; low-quality evidence). Bovine pericardium patch compared with other synthetic patch angioplasty Bovine pericardium versus PTFE patch materials  Evidence suggests that bovine pericardium patch results in a reduction in long-term ipsilateral stroke (OR 4.17, 95% CI 0.46 to 38.02; 1 study, 195 participants; low-quality evidence). Bovine pericardial patch may reduce the risk of perioperative fatal stroke, death, and infection compared to synthetic material (OR 5.16, 95% CI 0.24 to 108.83; 2 studies, 290 participants; low-quality evidence for PTFE, and low-quality evidence for Dacron; OR 4.39, 95% CI 0.48 to 39.95; 2 studies, 290 participants; low-quality evidence for PTFE, and low-quality evidence for Dacron; OR 7.30, 95% CI 0.37 to 143.16; 1 study, 195 participants; low-quality evidence, respectively), but the numbers of outcomes were small. The evidence is very uncertain about effects of the patch on infection outcomes. AUTHORS' CONCLUSIONS: The number of outcome events is too small to allow conclusions, and more trial data are required to establish whether any differences do exist. Nevertheless, there is little to no difference in effect on perioperative and long-term ipsilateral stroke between vein and any synthetic patch material. Some evidence indicates that other synthetic patches (e.g. PTFE) may be superior to Dacron grafts in terms of perioperative stroke and TIA rates, and both early and late arterial re-stenosis and occlusion. Pseudoaneurysm formation may be more common after use of a vein patch than after use of a synthetic patch. Bovine pericardial patch, which is an acellular xenograft material, may reduce the risk of perioperative fatal stroke, death, and infection compared to other synthetic patches. Further large RCTs are required before definitive conclusions can be reached.


Assuntos
Prótese Vascular , Endarterectomia das Carótidas/métodos , Polietilenotereftalatos , Politetrafluoretileno , Acidente Vascular Cerebral/prevenção & controle , Falso Aneurisma/epidemiologia , Angioplastia/métodos , Viés , Bioprótese , Prótese Vascular/efeitos adversos , Estenose das Carótidas , Endarterectomia das Carótidas/classificação , Endarterectomia das Carótidas/mortalidade , Humanos , Polietilenotereftalatos/efeitos adversos , Politetrafluoretileno/efeitos adversos , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/mortalidade , Complicações Pós-Operatórias/prevenção & controle , Ensaios Clínicos Controlados Aleatórios como Assunto , Veia Safena , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/mortalidade
4.
Waste Manag ; 124: 273-282, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33639412

RESUMO

Polyethylene terephthalate (PET) is a widely used plastic material that may cause significant environmental pollution. China is a major global producer and consumer of PET. Previous studies have focused on the effects of toxic elements from PET (e.g., antimony leached from PET products) on the environment. However, detailed information about PET, particularly about the PET production, trade, use, and recycling in China, is limited. This study developed a network model of PET flows in China, including the production, market trade, manufacturing and use, and waste management and recycling stages. Based on this network model, the characteristics of PET flows during three periods of development for the PET industry were analyzed. The results show that the fiber and bottle manufacturing industries are the industries with the largest PET in-use stocks. The PET flows showed different characteristics in the terms of waste import, recycling, and disposal (mechanical recycling, chemical recycling, incineration, landfill, and discarding) in the different periods of PET industrial development. Notably, the amount of discarded PET was significant, and the treatment of waste PET would probably be a challenge in the future. Policies for improving the PET cycling system were provided on the basis of the study results to promote the management and sustainable utilization of PET materials.


Assuntos
Polietilenotereftalatos , Gerenciamento de Resíduos , China , Plásticos , Reciclagem
5.
Mar Pollut Bull ; 165: 112176, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33621904

RESUMO

Spatiotemporal distribution and ecological risk of the polyethylene terephthalate (PET) plastic polymer and plasticizer di-(2-ethylhexyl) phthalate (DEHP) were investigated using both surface and core sediments in Jiaozhou Bay, China. The concentrations of PET and DEHP ranged 210.6-1929.7 µg/kg and 0-591.2 µg/kg, respectively. The depth profiles of PET and DEHP in the sediment cores indicated that PET and DEHP pollution increased since the 1970s, which is in accord with the regional PET and DEHP consumption history. The levels of PET in Jiaozhou Bay was found to represent low ecological risk based on the assessment models for Potential Ecological Risk factor and Potential Ecological Risk. The amounts of DEHP also posed a low risk to the aquatic organisms in the sediment phase as indicated by the Risk Quotient method.


Assuntos
Dietilexilftalato , Ácidos Ftálicos , Poluentes Químicos da Água , Baías , China , Dietilexilftalato/análise , Ácidos Ftálicos/análise , Polietilenotereftalatos , Rios , Poluentes Químicos da Água/análise
6.
Food Chem ; 347: 129040, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33484960

RESUMO

An Ultra High-Performance Liquid chromatography method quadruple time-of-flight mass spectrometry has been developed for the analysis of 11 cyclic polyesters oligomers, following a modified QuEChERS clean-up with alumina/primary secondary amine, in pasta. Target analytes were polyethylene terephthalate (PET) 1st series cyclic dimer to heptamer, polybutylene terephthalate (PBT) dimer to pentamer and a polyurethane oligomer. Standard addition method was applied for the calibration, and the limits of quantification ranged from 3.2 to 17.2 ng g-1. Recoveries ranged from 86.4 to 109.8%, RSDs were lower than 12% for all analytes, and matrix effect never exceeded ± 2.5%. The method was successfully applied to real commercial pasta samples, where the PET 1st series cyclic trimer was the most abundant oligomer, being found in all tested samples. The 1st series PET cyclic dimer and tetramer, as well as 1,4,7-trioxacyclotridecane-8,13-dione, were found in considerable amounts. Traces of the 2nd and 3rd series PET cyclic dimers were also found.


Assuntos
Análise de Alimentos/métodos , Espectrometria de Massas/métodos , Poliésteres/química , Polietilenotereftalatos/química , Óxido de Alumínio/química , Cromatografia Líquida de Alta Pressão , Dimerização , Farinha/análise , Poliésteres/análise , Polietilenotereftalatos/análise , Polimerização , Dióxido de Silício/química
7.
Am J Otolaryngol ; 42(2): 102872, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33418177

RESUMO

AIM: This study was aimed to compare the virological, suspect reported outcomes and provider preferences during COVID-19 swab taking procedure used for sampling. METHODS: The COVID-19 suspects are subjected to nasopharyngeal (NP) and oropharyngeal (OP) swabs for testing. Two types of swabs (Nylon and Dacron) are used for sample collection. Prospectively each suspect's response is collected and assessed for self-reported comfort level. The provider's experience with each suspect and virological outcomes recorded separately. The sample adequacy was compared based on swab types and demographic characteristics. RESULTS: A total of 1008 COVID-19 suspects were considered for comparison of various outcomes. Dacron and flocked Nylon swab sticks are used for taking 530 and 478 samples, respectively. Suspects who underwent the procedure using Nylon swabs were six times more likely to have pain/discomfort compared to when Dacron swab was used (Adj RR (95% CI: 6.76 (3.53 to 13, p=0.0001))). The providers perceived six times more resistance with the Nylon swabs compared to Dacron Swabs (Adj RR (95% CI: 5.96 (3.88 to 9.14, p=0.0001))). The pediatric population had a higher rate of blood staining in Dacron swab [Dacron 66 (80.5%); Nylon 51 (54.8%) p=0.0001]. The sample adequacy rate and laboratory positivity rate were not significantly different from each other. CONCLUSIONS: Given the comparable virological outcomes, the difference in suspect and providers comfort should drive swab selection based on characteristics of the suspects. The bulbous Nylon swab caused more pain/discomfort in adults compared to Dacron.


Assuntos
Atitude do Pessoal de Saúde , Nasofaringe/virologia , Orofaringe/virologia , Conforto do Paciente , Manejo de Espécimes/instrumentação , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Nylons , Polietilenotereftalatos , Estudos Prospectivos , Adulto Jovem
8.
Chemosphere ; 270: 129430, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33388502

RESUMO

Polyethylene terephthalate (PET) is one of the main plastic polymers contaminating natural ecosystems. Although PET microplastics (PET-MPs) have been found in both aquatic and terrestrial ecosystems, the information concerning their potential toxicity towards terrestrial organisms is limited. The present study aimed at investigating the ingestion and the possible adverse effects induced by a 40-days exposure to irregular shaped PET-MPs toward the giant snail Achatina reticulata. Giant snails were exposed via the diet to two concentrations (1% and 10% w/w; i.e., g of PET-MPs/g of the administered food) of PET-MPs and their capability to ingest and egest PET-MPs was assessed together with an evaluation of their potential effects at biochemical and individual levels. Oxidative stress-related biomarkers (i.e., the amount of reactive oxygen species, the activity of antioxidant enzymes and lipid peroxidation) and DNA fragmentation were measured in the digestive gland isolated from snails as biochemical endpoints. Changes in growth trajectories, in terms of body weight and shell size, were considered as morphometric endpoints. Our results demonstrated that A. reticulata can efficiently ingest and egest PET-MPs. Whilst giant snails did not experience an oxidative stress condition, significant changes in their growth trajectories were observed, with PET-MPs-treated snails grew more and more quickly than the control group. Our results suggest that PET-MPs might represent a risk during early-life stages for terrestrial organisms.


Assuntos
Microplásticos , Poluentes Químicos da Água , Animais , Exposição Dietética , Ecossistema , Estresse Oxidativo , Plásticos/toxicidade , Polietilenotereftalatos , Caramujos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
9.
Ecotoxicol Environ Saf ; 208: 111718, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396049

RESUMO

Plastics enter in terrestrial natural system primarily by agricultural purposes, while acid rain is the result of anthropogenic activities. The synergistic effects of microplastics and acid rain on plant growth are not known. In this study, different sizes of polyethylene terephthalate (PET) and acid rain are tested on Lepidium sativum, in two separate experimental sets. In the first one we treated plants only with PET, in the second one we used PET and acid rain together. In both experimentations we analyzed: i) plant biometrical parameters (shoot height, leaf number, percentage inhibition of seed germination, fresh biomass), and ii) oxidative stress responses (hydrogen peroxide; ascorbic acid and glutathione). Results carried out from our experiments highlighted that different sizes of polyethylene terephthalate are able to affect plant growth and physiological responses, with or without acid rain supplied during acute toxicity (6 days). SHORT DESCRIPTION: This study showed that different sizes of PET microplastics affect physiological and biometrical responses of Lepidum sativum seedlings, with or without acid rain; roots and leaves responded differently.


Assuntos
Chuva Ácida/toxicidade , Lepidium sativum/efeitos dos fármacos , Microplásticos/toxicidade , Polietilenotereftalatos/toxicidade , Poluentes Químicos da Água/toxicidade , Lepidium sativum/crescimento & desenvolvimento , Lepidium sativum/metabolismo , Lepidium sativum/fisiologia , Microplásticos/química , Estresse Oxidativo/efeitos dos fármacos , Tamanho da Partícula , Folhas de Planta/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Polietilenotereftalatos/química , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Poluentes Químicos da Água/química
10.
Sensors (Basel) ; 21(2)2021 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-33445532

RESUMO

Flexible electronics with continuous monitoring ability a extensively preferred in various medical applications. In this work, a flexible pressure sensor based on porous graphene (PG) is proposed for continuous cardiovascular status monitoring. The whole sensor is fabricated in situ by ink printing technology, which grants it the potential for large-scale manufacture. Moreover, to enhance its long-term usage ability, a polyethylene terephthalate/polyethylene vinylacetate (PET/EVA)-laminated film is employed to protect the sensor from unexpected shear forces on the skin surface. The sensor exhibits great sensitivity (53.99/MPa), high resolution (less than 0.3 kPa), wide detecting range (0.3 kPa to 1 MPa), desirable robustness, and excellent repeatability (1000 cycles). With the assistance of the proposed pressure sensor, vital cardiovascular conditions can be accurately monitored, including heart rate, respiration rate, pulse wave velocity, and blood pressure. Compared to other sensors based on self-supporting 2D materials, this sensor can endure more complex environments and has enormous application potential for the medical community.


Assuntos
Sistema Cardiovascular , Grafite/química , Monitorização Fisiológica/instrumentação , Dispositivos Eletrônicos Vestíveis , Adulto , Pressão Sanguínea , Desenho de Equipamento , Frequência Cardíaca , Humanos , Tinta , Monitorização Fisiológica/métodos , Polietilenotereftalatos/química , Polivinil/química , Porosidade , Análise de Onda de Pulso/instrumentação , Análise de Onda de Pulso/métodos , Respiração , Pele , Difração de Raios X
11.
Food Chem ; 347: 129006, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33472117

RESUMO

Multilayer bottles consisting of chitosan (CS), microcrystalline cellulose (MCC), whey protein isolate (WPI), and polyethylene terephthalate (PET) were tested as novel materials for packaging and extending shelf life of rosebud beverages. We studied the storage stability at 4 °C, 25 °C, 37 °C, and 55 °C by assessing the physical and biochemical parameters. The results show that multilayer PET bottles had better barrier performance and improved soluble solids content, pH, polyphenol content, color indices, and browning degree in rosebud beverages over the control at all studied temperatures. A shelf life model was established based on the Arrhenius equation, and the number of days when polyphenol contents dropped to <50% of the initial content was defined as the shelf life. Our results highlight the reliability of the prediction model, and we conclude that packaging rosebud beverages in multilayer PET bottles significantly extends the product shelf life, and this benefit was further extended at low temperatures.


Assuntos
Bebidas/análise , Celulose/química , Quitosana/química , Embalagem de Alimentos/métodos , Polietilenotereftalatos/química , Proteínas do Soro do Leite/química , Cor , Armazenamento de Alimentos , Concentração de Íons de Hidrogênio , Polifenóis/química , Temperatura
12.
Food Chem ; 345: 128739, 2021 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-33333359

RESUMO

A HPLC-UV/FLD method was validated for the quantification of six polyethylene terephthalate (PET) and four polybutylene terephthalate (PBT) oligomers. PBT oligomers are EU regulated, while the PET ones are considered non-intentionally added substances (NIAS). LOQs were higher than 0.4 and 3.5 µg kg-1 for the simulants and in the polymer extracts, respectively. Recoveries ranged from 95 to 114 % with RSDs below 12%. Migration testing of PBT and polypropylene coffee capsules were performed with H2O and simulant C, and extracts were obtained with accelerated solvent extraction (ASE). For the latter legislative limits weren't surpassed. As no migration limits are existing for the analytes, both EFSA's toxicological threshold of concern (TTC) and sum of oligomers approaches were applied. The majority of oligomers were below the TTC (90 µg/person/day), but the limit value of 50 µg/kg food was surpassed for some capsules, which indicates a significant intake in both single and multiple consumption.


Assuntos
Café/química , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Embalagem de Alimentos , Poliésteres/análise , Polietilenotereftalatos/análise , Polimerização , Cromatografia Líquida de Alta Pressão , Ciclização , Poliésteres/química , Poliésteres/isolamento & purificação , Polietilenotereftalatos/química , Polietilenotereftalatos/isolamento & purificação
13.
Diagn Microbiol Infect Dis ; 99(1): 115209, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33080426

RESUMO

Nasopharyngeal flocked swabs placed in viral transport media (VTM) are the preferred collection methodology for respiratory virus testing. Due to the rapid depletion of available reagents and swabs, we have validated an alternative swab placed in phosphate-buffered saline (PBS) for use in respiratory virus testing in a SARS-CoV-2 real-time polymerase chain reaction assay and a multiplexed respiratory virus panel. We collected nasopharyngeal (NP) swabs and oropharyngeal (OP) swabs from 10 healthy volunteers. Flocked swabs were placed in VTM and alternative swabs in PBS. In this feasibility study, we show that NP collection is better for detection of human material than OP collection, as measured by significantly lower RNase P gene cycle threshold values, and that a Dacron polyester swab in PBS shows equivalent detection of SARS-CoV-2 and RSV to a flocked swab in VTM in contrived specimens. Diluted SARS-CoV-2-positive patient specimens are detectable for up to 72 h at 4 °C.


Assuntos
/diagnóstico , Manejo de Espécimes/métodos , Meios de Cultura , Estudos de Viabilidade , Humanos , Nasofaringe/virologia , Orofaringe/virologia , Polietilenotereftalatos , Vírus Sincicial Respiratório Humano/genética , Vírus Sincicial Respiratório Humano/isolamento & purificação , /genética
14.
Water Res ; 190: 116731, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33310440

RESUMO

The entering of the widespread polyethylene terephthalate (PET) microplastics into biological wastewater treatment system results in their retention in sewage sludge, which inevitably enters the sludge treatment system. However, all previous studies regarding the impact of microplastics on sludge treatment system were conducted by directly adding microplastics to system and focusing on anaerobic sludge digestion, although PET microplastics commonly enter into the biological wastewater treatment system first before sludge being subsequently treated. The potential impact of the microplastics on waste activated sludge (WAS) aerobic digestion is also completely missing. Therefore, herein the influences of PET microplastics with different entry paths on WAS aerobic digestion as well as the key mechanisms involved was firstly explored. Experimental results demonstrated that compared to the control test, the entering of PET microplastics to biological wastewater treatment system inhibited WAS aerobic digestion by 10.9 ± 0.1% through the decreased hydrolysis, although WAS solubilization during aerobic digestion was improved due to the change of generated WAS characteristics. In contrast, when PET microplastics was directly added to the sludge aerobic digester, there was little impact on solubilization, while the hydrolysis were inhibited seriously, thereby suppressing WAS aerobic digestion more severely by 28.9 ± 0.1%. Further investigation revealed that PET microplastics reduced the populations of key bacteria (e.g., Saprospiraceae, Chitinophagaceae and Xanthomonadaceae) involved in aerobic digestion via induced oxidative stress or/and releasing toxic chemical. This study provided a more accurate approach to assessing the real situation regarding the influences of PET microplastics on aerobic sludge digestion.


Assuntos
Esgotos , Purificação da Água , Anaerobiose , Reatores Biológicos , Digestão , Microplásticos , Plásticos , Polietilenotereftalatos , Eliminação de Resíduos Líquidos , Águas Residuárias
15.
Environ Pollut ; 271: 116262, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33360657

RESUMO

In recent years, many studies are focusing on the negative effects of plastic pollution, and in particular on the nanosized plastic fragments and their implications on the environment and human health. Nanoplastics in the environment interact with a great number of substances, many of which are dangerous to humans, but the interaction mechanisms, the complexes formation processes, and their biological impact are still poorly understood. Here we report a study on the interactions of polyethylene terephthalate nanoplastics, produced by laser ablation, with three different types of contaminants: glyphosate, levofloxacin and Hg2+ ions, and we demonstrate that the nanoplastics form complexes with all three contaminants through their favorable binding. Most importantly, this study highlights that to demonstrate the overall effect of the nanoplastics internalized by cells in vitro, it is important to combine alternative methodologies, such as metabolomics, with standard biological assays (i.e., cell viability and ROS production). In this way it becomes possible to better understand the body's response to this new class of pollutants and their possible chronic toxicity. Summary: PET nanoplastics, fabricated by laser ablation, interact with aqueous pollutants forming nanoclusters. The nanoclusters affect the cells metabolism, suggesting long-term risks.


Assuntos
Microplásticos , Poluentes Químicos da Água , Poluição Ambiental , Humanos , Plásticos/toxicidade , Polietilenotereftalatos , Água , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
16.
Sci Total Environ ; 757: 143735, 2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33310567

RESUMO

Multiple studies in freshwater environments have verified that microplastic particles are present in water columns, sediment, and aquatic organisms. These studies indicated that certain freshwater ecosystems may act as temporary sinks of microplastic particles, leading to accumulation in the sediment and the ingestion by benthic organisms. Polyethylene terephthalate (PET) is one of the non-buoyant polymers that has been frequently found in aquatic sediments. This study aims to investigate a possible transfer of PET microfibers from aquatic to the terrestrial habitats and addressed selected effects (i.e. survival, general stress response, and growth) of PET microfibers using Chironomus riparius, a frequently applied model organism in ecotoxicological research. To assess the growth and development of C. riparius, a modified 28-day sediment chronic toxicity test was conducted, in which the main endpoint is time until emergence of the larvae. In this assay, C. riparius were exposed to artificial sediments spiked with PET microfibers. In addition, weight and head capsule lengths of the larvae were also measured. As a general stress response marker on the molecular level, Heat Shock Protein 70 (HSP70) levels were measured in two involved life stages, i.e. larvae and adults. Using staining method, ingestion of PET microfibers was verified in the adult sample. Our results clearly demonstrated that ingested microfibers by C. riparius larvae can be carried through subsequent life stages and end up in the adults. Accordingly, this is the first proof of aquatic-terrestrial transfer of PET microfibers for C. riparius. However, toxicity test results showed that there was no significant effect on the time until emergence, weight or head capsule lengths in the organisms exposed to PET microfibers compared to control organisms. HSP70 measurements showed no significant effects between control and exposure groups in the same life stage. The result suggests that PET microfibers in the applied concentration do not exert adverse effects both on organism and subcellular level in one generation.


Assuntos
Chironomidae , Poluentes Químicos da Água , Animais , Ecossistema , Sedimentos Geológicos , Larva , Plásticos , Polietilenotereftalatos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
17.
Environ Pollut ; 270: 116192, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33338957

RESUMO

Polyethylene terephthalate (PET) is a possible key component of nanoplastics in water environments, which can migrate pollutants through co-transport. In this regard, the co-transport of endocrine disruptors (such as bisphenol A, BPA) by nanoplastics is of emergent concern because of its cytotoxicity/bioaccumulation effects in aquatic organisms. In this work, a computational study is performed to reveal the BPA adsorption mechanism onto PET nanoplastics (nanoPET). It is found that the outer surface of nanoPET has a nucleophilic nature, allowing to increase the mass transfer and intraparticle diffusion into the nanoplastic to form stable complexes by inner and outer surface adsorption. The maximum adsorption energy is similar (even higher) in magnitude with respect to nanostructured adsorbents such as graphene, carbon nanotubes, activated carbon, and inorganic surfaces, indicating the worrying adsorption properties of nanoPET. The adsorption mechanism is driven by the interplay of dispersion (38-49%) and electrostatics effects (43-50%); specifically, dispersion effects dominate the inner surface adsorption, while electrostatics energies dominate the outer surface adsorption. It is also determined that π-π stacking is not a reliable interaction mechanism for aromatics on nanoPET. The formed complexes are also highly soluble, and water molecules behave as non-competitive factors, establishing the high risk of nanoPET to adsorb and migrate pollutants in water ecosystems. Furthermore, the adsorption performance is decreased (but not inhibited) at high ionic strength in salt-containing waters. Finally, these results give relevant information for environmental risk assessment, such as quantitative data and interaction mechanisms for non-biodegradable nanoplastics that establish strong interactions with pollutants in water.


Assuntos
Nanotubos de Carbono , Poluentes Químicos da Água , Adsorção , Compostos Benzidrílicos , Ecossistema , Microplásticos , Modelos Teóricos , Fenóis , Polietilenotereftalatos , Poluentes Químicos da Água/análise
18.
Waste Manag ; 119: 101-110, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33049515

RESUMO

The increasing amount of marine plastic waste poses challenges including, not only the collection, but also the subsequent recyclability of the plastic. An artificial accelerated weathering procedure was developed, which modelled the marine environment and investigated the recyclability of weathered and non-weathered PET. Marine conditions were simulated for poly(ethylene terephthalate) (PET) bottle material and high-density polyethylene (HDPE) cap material. It consisted of 2520 h cyclical weathering, alternating the sample between a salt spray and a Xenon-chamber-this corresponds to roughly 3-4 years on the surface of an ocean. It was proved that the molecular weight of PET is a function of weathering time and can be described mathematically. Microscopic examination of the surface of the PET bottles and HDPE caps proved that these surfaces were damaged. After weathering, manufacturing tests were performed on the PET material by extrusion, injection moulding, 3D printing and thermoforming. Quantitative comparison between products manufactured by the same technology was performed in order to compare the qualities of products made from original PET, non-weathered PET waste, which was the example of classical recycling, and weathered PET. In the case of products made from weathered PET, certain mechanical and optical properties (e.g. impact strength and transparency) were significantly impaired compared to the original PET and the recycled, non-weathered PET. Certain other properties (e.g. strength and rigidity) did not change significantly. It was proved that the samples from weathered plastic material can be successfully recycled mechanically and used to manufacture plastic products.


Assuntos
Plásticos , Reciclagem , Polietileno , Polietilenotereftalatos , Tecnologia
19.
Mar Pollut Bull ; 160: 111624, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32911117

RESUMO

The effects of microplastics (MPs) on the ecological functioning in marine sediments is largely unknown. However, coastal marine sediments and their resident communities play critical roles in the transformation of organic matter and the cycling of nutrients that influence both local and global processes. To investigate how microplastics influence ecosystem functions associated with sediment biogeochemistry, large bivalves and microphytobenthos, we conducted a 31-day laboratory experiment. The experiment tested the role of micro-polyethylene terephthalate (mPETs) at five concentrations (0%, 1%, 3%, 6%, and 8% based on wet weight of top 1 cm sediment). Canonical principle of coordinate analysis (CAP) was applied to assess change on the ecosystem functionality with increasing concentrations of mPETs. Our results highlight that stress effects on ecosystem function are the product of the interaction between Macomona liliana, microphytobenthos and mPETs.


Assuntos
Ecossistema , Poluentes Químicos da Água , Animais , Monitoramento Ambiental , Sedimentos Geológicos , Microplásticos , Plásticos , Polietilenotereftalatos , Poluentes Químicos da Água/análise
20.
Proc Natl Acad Sci U S A ; 117(41): 25476-25485, 2020 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-32989159

RESUMO

Plastics pollution represents a global environmental crisis. In response, microbes are evolving the capacity to utilize synthetic polymers as carbon and energy sources. Recently, Ideonella sakaiensis was reported to secrete a two-enzyme system to deconstruct polyethylene terephthalate (PET) to its constituent monomers. Specifically, the I. sakaiensis PETase depolymerizes PET, liberating soluble products, including mono(2-hydroxyethyl) terephthalate (MHET), which is cleaved to terephthalic acid and ethylene glycol by MHETase. Here, we report a 1.6 Å resolution MHETase structure, illustrating that the MHETase core domain is similar to PETase, capped by a lid domain. Simulations of the catalytic itinerary predict that MHETase follows the canonical two-step serine hydrolase mechanism. Bioinformatics analysis suggests that MHETase evolved from ferulic acid esterases, and two homologous enzymes are shown to exhibit MHET turnover. Analysis of the two homologous enzymes and the MHETase S131G mutant demonstrates the importance of this residue for accommodation of MHET in the active site. We also demonstrate that the MHETase lid is crucial for hydrolysis of MHET and, furthermore, that MHETase does not turnover mono(2-hydroxyethyl)-furanoate or mono(2-hydroxyethyl)-isophthalate. A highly synergistic relationship between PETase and MHETase was observed for the conversion of amorphous PET film to monomers across all nonzero MHETase concentrations tested. Finally, we compare the performance of MHETase:PETase chimeric proteins of varying linker lengths, which all exhibit improved PET and MHET turnover relative to the free enzymes. Together, these results offer insights into the two-enzyme PET depolymerization system and will inform future efforts in the biological deconstruction and upcycling of mixed plastics.


Assuntos
Proteínas de Bactérias/metabolismo , Burkholderiales/enzimologia , Plásticos/metabolismo , Engenharia de Proteínas/métodos , Modelos Moleculares , Mutação , Plásticos/química , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Conformação Proteica , Domínios Proteicos , Especificidade por Substrato
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