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Proceedings of the Institution of... Nov 2019Evaluation and prediction of wear play a key role in product design and material selection of total hip replacements, because wear debris is one of the main causes of... (Review)
Review
Evaluation and prediction of wear play a key role in product design and material selection of total hip replacements, because wear debris is one of the main causes of loosening and failure. Multifactorial clinical or laboratory studies are high cost and require unfeasible timeframes for implant development. Simulation using finite element methods is an efficient and inexpensive alternative to predict wear and pre-screen various parameters. This article presents a comprehensive literature review of the state-of-the-art finite element modelling techniques that have been applied to evaluate wear in polyethylene hip replacement components. A number of knowledge gaps are identified including the need to develop appropriate wear coefficients and the analysis of daily living activities.
Topics: Arthroplasty, Replacement, Hip; Finite Element Analysis; Humans; Mechanical Phenomena; Polyethylene
PubMed: 31466506
DOI: 10.1177/0954411919872630 -
Environmental Toxicology and... Aug 2023Co-exposure of tetracycline (TC) and polyethylene microplastic (MP-PE) pollution might result in more intricate effects on rice growth and grain quality. In present...
Co-exposure of tetracycline (TC) and polyethylene microplastic (MP-PE) pollution might result in more intricate effects on rice growth and grain quality. In present study, two different rice cultivars of contrasting drought tolerance, Hanyou73 (H73, drought-resistant) and Quanyou280 (Q280, drought-sensitive) were grown on MP-PE and TC-contaminated soils under drought. It was found that drought stress had different influence on TC accumulation in the two rice cultivars. H73 accumulated more TC in leaves and grains without drought stress while Q280 accumulated more TC under drought stress. Furthermore, metabolomics results demonstrated that under drought stress, about 80 % of metabolites in H73 and 95 % in Q280 were down-regulated as compared to non-drought treatments. These findings provide insights into the effects of TC and MP-PE with and without drought stress on potential risks to rice growth and grain quality, which has implications on rice production and cultivar election under multiple-stress conditions.
Topics: Oryza; Plastics; Polyethylene; Microplastics; Edible Grain; Tetracyclines; Stress, Physiological
PubMed: 37343773
DOI: 10.1016/j.etap.2023.104191 -
Water Research Aug 2022Microplastics are ubiquitous and consequently enter drinking water treatment plants. Knowledge of the microplastic fate in drinking water production is still very...
Microplastics are ubiquitous and consequently enter drinking water treatment plants. Knowledge of the microplastic fate in drinking water production is still very limited, although explorative studies have shown tap water contains low contents of microplastics. In this study, we measure microplastic concentrations in drinking water sources and assess the effectiveness of various drinking water treatment facilities to reduce the microplastic concentrations in water to gain insight into the fate of microplastics. Two analytical techniques, laser direct infrared spectroscopy (LDIR) and optical microscopy, have been applied to cover the particle size range from 20 µm to 5 mm. In total five different drinking water sites were investigated using four different types of raw water (groundwater, surface water, dune filtrate and riverbank filtrate) for drinking water production. This research shows that drinking water treatment removes the majority of microplastics and that concentration of microplastics larger than 20 µm in tap water is less than 2 microplastics particles per litre. Between the different raw water sources it is found that groundwater had by far the lowest microplastics concentrations (< 1.000 microplastics per m) and the highest concentration was found in riverine water, up to 460.000 particles per m, specifically in the Lek Canal () (a canal connected to the river Rhine). On average the most abundant plastics found are polyamide (PA, 33%), polyethylene terephthalate (PET, 15%), rubbers (10%), polyethylene (PE, 10%) and chlorinated polyethylene (CPE, 7%). This study also showed that natural treatment steps, such as dune infiltration and sedimentation, remove microplastics effectively. However, this may introduce an adverse effect where microplastics potentially accumulate in the sediment and environment.
Topics: Drinking Water; Environmental Monitoring; Microplastics; Plastics; Polyethylene; Rivers; Water Pollutants, Chemical
PubMed: 35780766
DOI: 10.1016/j.watres.2022.118790 -
Environmental Pollution (Barking, Essex... Apr 2021Polyethylene (PE) is the most abundant non-degradable plastic waste, posing a constant and serious threat to the whole ecosystem. In the present study, the fungal...
Polyethylene (PE) is the most abundant non-degradable plastic waste, posing a constant and serious threat to the whole ecosystem. In the present study, the fungal community of plastic wastes contaminating a landfill soil has been studied. After 6 months of enrichment, 95 fungi were isolated, mostly belonging to the Ascomycota phylum. They were screened under in vitro condition: most of fungi (97%) were capable of growing in the presence of PE powder (5-10 g L) as sole carbon source. Fusarium strains better tolerated high concentration of PE. Up to 13 strains were chosen for further degradation trails, where the process was monitored by respirometry tests and by observing changes in PE chemical and physical structure by FTIR analysis and SEM images. Major results were observed for Fusarium oxysporum, Fusarium falciforme and Purpureocillum lilacinum, as they caused strong oxidation phenomena and changes in the PE film morphology. Results suggested that the initial oxidation mechanisms targeted first the methyl terminal groups. Changes in the infrared spectra were strongly strain-dependent, denoting the activation of different degradation pathways. Through the SEM analysis, the actual damages provoked by fungi were observed, including swellings, pits and furrows, bumps and partial exfoliations. Considering the rising concern about plastic disposal worldwide, the ability of these fungi to colonize PE and utilize it as carbon source is of great interest, as no pretreatments and pro-oxidant stimulants were needed.
Topics: Biodegradation, Environmental; Ecosystem; Fungi; Fusarium; Polyethylene
PubMed: 33540258
DOI: 10.1016/j.envpol.2021.116548 -
Hernia : the Journal of Hernias and... Dec 2020In Africa and other Low Resource Settings (LRS), the guideline-based and thus in most cases mesh-based treatment of inguinal hernias is only feasible to a very limited...
INTRODUCTION
In Africa and other Low Resource Settings (LRS), the guideline-based and thus in most cases mesh-based treatment of inguinal hernias is only feasible to a very limited extent. This has led to an increased use of low cost meshes (LCMs, mostly mosquito meshes) for patients in LRS. Most of the LCMs used are made of polyethylene or polyester, which must be sterilized before use. The aim of our investigations was to determine changes in the biocompatibility of fibroblasts as well as mechanical and chemical properties of LCMs after steam sterilization.
MATERIAL AND METHODS
Two large-pored LCMs made of polyester and polyethylene in a size of 11 x 6 cm were cut and steam sterilized at 100, 121 and 134 °C. These probes and non-sterile meshes were then subjected to mechanical tensile tests in vertical and horizontal tension, chemical analyses and biocompatibility tests with human fibroblasts. All meshes were examined by stereomicroscopy, scanning electron microscopy (SEM), LDH (cytotoxicity) measurement, viability testing, pH, lactate and glycolysis determination.
RESULTS
Even macroscopically, polyethylene LCMs showed massive shrinkage after steam sterilization, especially at 121 and 134 °C. While polyester meshes showed no significant changes after sterilization with regard to deformation and damage as well as tensile force and stiffness, only the unsterile polyethylene mesh and the mesh sterilized at 100 °C could be tested mechanically due to the shrinkage of the other specimen. For these meshes the tensile forces were about four times higher than for polyester LCMs. Chemical analysis showed that the typical melting point of polyester LCMs was between 254 and 269 °C. Contrary to the specifications, the polyethylene LCM did not consist of low-density polyethylene, but rather high-density polyethylene and therefore had a melting point of 137 °C, so that the marked shrinkage described above occurred. Stereomicroscopy confirmed the shrinkage of polyethylene LCMs already after sterilization at 100 °C in contrast to polyester LCMs. Surprisingly, cytotoxicity (LDH measurement) was lowest for both non-sterile LCMs, while polyethylene LCMs sterilized at 100 and 121 °C in particular showed a significant increase in cytotoxicity 48 hours after incubation with fibroblasts. Glucose metabolism showed no significant changes between sterile and non-sterile polyethylene and polyester LCMs.
CONCLUSION
The process of steam sterilization significantly alters mechanical and structural properties of synthetic hernia mesh implants. Our findings do not support a use of low-cost meshes because of their unpredictable properties after steam sterilization.
Topics: Female; Humans; Male; Polyethylene; Steam; Sterilization; Surgical Mesh
PubMed: 32975699
DOI: 10.1007/s10029-020-02272-w -
Marine Pollution Bulletin Mar 2023This study reports first evidence of microplastic detection in the Patella caerulea collected from 5 different stations located in İskenderun Bay and Mersin Bay. A...
This study reports first evidence of microplastic detection in the Patella caerulea collected from 5 different stations located in İskenderun Bay and Mersin Bay. A total of 160 P. caerulea specimens were examined and 40 of them contained MPs in their soft tissues. The number of microplastics extracted per sample varied from 0.20 ± 0.5 items/ind to 0.45 ± 0.7 items/ind depending on station. Fibers were predominant type of MPs and accounted for 75 % to 87.5 % of total extracted MPs, followed by fragments (12.5-25 %). Majority of MPs were 0.5-1 mm size and black in color. Fourier transform infrared spectroscopy (FTIR) showed that the extracted MPs were polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), high density polyethylene (HDPE). This study contributes to the knowledge of the transfer of microplastics to the marine food web and highlights the need for protective measurements.
Topics: Microplastics; Plastics; Mediterranean Sea; Patella; Environmental Monitoring; Water Pollutants, Chemical; Polyethylene
PubMed: 36731374
DOI: 10.1016/j.marpolbul.2023.114684 -
Environmental Research Aug 2023Environment plastic litter accumulation is a significant concern, needing urgent advancements in plastic waste management. Recent investigations into plastic... (Review)
Review
Environment plastic litter accumulation is a significant concern, needing urgent advancements in plastic waste management. Recent investigations into plastic biodegradation by bacteria and their enzymes are creating exciting unique opportunities for the development of biotechnological plastic waste treatment methods. This review summarizes information on bacterial and enzymatic biodegradation of plastic in a wide range of synthetic plastics such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyurethane (PUR), polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC). Plastic biodegradation is facilitated by Acinetobacter, Bacillus, Brevibacillus, Escherichia, Pseudomonas, Micrococcus, Streptomyces, and Rhodococcus bacteria, and enzymes such as proteases, esterases, lipases, and glycosidases. Molecular and analytical procedures used to analyze biodegradation processes are outlined, as are the obstacles in verifying plastic breakdown using these methods. Taken together, the findings of this study will contribute significantly to the construction of a library of high-efficiency bacterial isolates and consortiums and their enzymes for use in plastic biosynthesis. This information is useful to researchers investigating plastic bioremediation and a supplement to the scientific and grey literature already accessible. Finally, the review focuses on expanding the understanding of bacterial capacity to break-down plastic utilizing modern biotechnological methods, bio-nanotechnological-based materials, and their future role in resolving pollution problems.
Topics: Plastics; Microplastics; Biodegradation, Environmental; Bacteria; Polyethylene
PubMed: 37172684
DOI: 10.1016/j.envres.2023.116110 -
Journal of Hazardous Materials Feb 2022A growing attention is attracted to the use of recycled plastics as food contact materials, and its chemical safety research and discrimination approach are...
A growing attention is attracted to the use of recycled plastics as food contact materials, and its chemical safety research and discrimination approach are indispensable. In current study, ultraviolet-visible spectrometry (UV-Vis) and ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) were used to provide spectral and mass fingerprinting for polyethylene (PE). Coupling with chemometrics, two methods were developed to discriminate recycled and virgin PE. UV-Vis combined with chemometrics could be a more accessible, simpler and faster approach. 237-331 nm in UV spectrum was regarded as marker region selected by orthogonal partial least-squares discrimination analysis (OPLS-DA) and the accuracy of both calibration and validation set could reach 100% in linear discrimination analysis (LDA) based on this region. Besides, 2314 ions were detected by UPLC-Q-TOF-MS and processed by MS-DIAL. 48 candidate chemicals were identified, including ketone, esters, carboxylic acid, alcohols and phenols, amine, nitriles, aldehydes and others. Possible origins of these compounds could be classified as plastic, food, drug, cosmetics and pesticide related. Many of these compounds are highly toxic, especially pesticide related, indicating that recycling in closed loop or sorting by the recycled plastic articles is very necessary if the recycled PE is going to be used as food contact material.
Topics: Chemometrics; Chromatography, High Pressure Liquid; Chromatography, Liquid; Mass Spectrometry; Polyethylene
PubMed: 34844336
DOI: 10.1016/j.jhazmat.2021.127165 -
Chemphyschem : a European Journal of... Jan 2020Whilst the formation of plastic nanoparticles (nanoplastics) from plastic wastes has been unequivocally evidenced, little is known about the effects of these materials...
Whilst the formation of plastic nanoparticles (nanoplastics) from plastic wastes has been unequivocally evidenced, little is known about the effects of these materials on living organisms at the subcellular or molecular levels. In the present contribution we show through molecular dynamics simulations that polyethylene nanoparticles dissolve in the hydrophobic core of lipid bilayers into a network of disentangled, single polymeric chains. The thereby induced structural and dynamic changes in the bilayer alter vital functions of the cell membrane, which if lacking a mechanism to decompose the polymer chains may result in the death of the cell.
Topics: Cell Membrane; Hydrophobic and Hydrophilic Interactions; Lipid Bilayers; Molecular Dynamics Simulation; Nanoparticles; Polyethylene
PubMed: 31483076
DOI: 10.1002/cphc.201900481 -
Plant Foods For Human Nutrition... Mar 2023This study aimed to evaluate the solar dryers' cover material effects on the colorimetric and physicochemical properties of pumpkin flowers (Cucurbita maxima). A direct...
This study aimed to evaluate the solar dryers' cover material effects on the colorimetric and physicochemical properties of pumpkin flowers (Cucurbita maxima). A direct cabinet solar dryer was designed using three cover types: polycarbonate, polyethylene, and aluminum with selective surface (titanium oxide coating). A unifactorial experimental design with three levels was adopted. Pumpkin flower stability was assured by reducing the initial moisture content (95.22%) and water activity (0.989) to 3.15% and 0.276 in the polycarbonate dryer, to 3.03% and 0.279 in the selective surface dryer, and 5.19% and 0.364 in the polyethylene dryer. The drying kinetics showed that the drying time needed to achieve the moisture equilibrium was 480, 540, and 720 min in the respective dryers, depending on the ambient conditions. The initial pumpkin flower hue angle was 76.52°; however, this value decreased to 74.81, 69.52, and 70.23° in the dryers with polycarbonate, polyethylene, and the selective surface respectively; this behavior indicates a pumpkin flower tendency to orange color. The dryer with the selective surface obtained the best properties in pumpkin flowers. The pumpkin flower showed an initial total soluble solid of 1.5°Brix increased to 30°Brix in the polycarbonate and polyethylene dryers and 39°Brix in the selective dryer. The titanium oxide dryer observed an increment in ascorbic acid content from 3.5 to 8.806 mg/100 g, whereas 6.45 and 5.87 mg/100 g in the polycarbonate and polyethylene dryer, respectively.
Topics: Cucurbita; Colorimetry; Flowers; Polyethylene
PubMed: 36370292
DOI: 10.1007/s11130-022-01032-8