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Materials (Basel, Switzerland) Jun 2024The integration of recycled polymers into additive manufacturing (AM) processes offers a promising opportunity for advancing sustainability within the manufacturing... (Review)
Review
The integration of recycled polymers into additive manufacturing (AM) processes offers a promising opportunity for advancing sustainability within the manufacturing industry. This review paper summarizes existing research and developments related to the use of recycled materials in AM, focusing on distinct polymers, such as polylactic acid (PLA), polyethylene terephthalate (PET), and acrylonitrile butadiene styrene (ABS), among others. Key topics explored include the availability of recycled filaments on the market, challenges associated with material variability and traceability, and efforts toward establishing ethical product standards and sustainability characterization methodologies. Regulatory considerations and standards development by organizations such as ASTM and ISO are discussed, along with recommendations for future advancements in improving the sustainability of filament recycling and achieving net-zero emissions in AM processes. The collective efforts outlined in this paper underscore the potential of recycled polymers in AM to foster a more sustainable and environmentally friendly manufacturing industry.
PubMed: 38930283
DOI: 10.3390/ma17122915 -
Materials (Basel, Switzerland) Jun 2024A novel UV-light-curable poly(ethylene glycol) diacrylate matrix composite material with unmodified and methacryloxyl-grafted TiO and TiO-ZrO systems was developed and...
A novel UV-light-curable poly(ethylene glycol) diacrylate matrix composite material with unmodified and methacryloxyl-grafted TiO and TiO-ZrO systems was developed and tested as a potential coating material for medical components. The main goal of the research was to evaluate how the addition of (un)modified inorganic oxide fillers affects the properties of the composition (viscosity, UV/Vis spectra), the kinetics of photocuring (photo-DSC), and the morphological (SEM), physicochemical, and thermal properties (DSC, TGA) of the resulting composites. The applied filler functionalization process decreased their polarity and changed their size, BET surface area, and pore volume, which influenced the viscosity and kinetics of the photocurable system. In addition, the addition of synthesized fillers reduced the polymer's glass transition temperature and increased its thermal stability. It was also observed that additional UV irradiation of the tested composite changed its surface, resulting in hydrophobic properties (with the addition of 7 wt.% filler, an increase in the contact angle by more than 45% was observed).
PubMed: 38930277
DOI: 10.3390/ma17122908 -
Materials (Basel, Switzerland) Jun 2024Graphite nanoplatelets (GNPs)-the segregated ultra-high molecular weight polyethylene (UHMWPE)-based composites with hybrid filler-decorated with FeO were developed....
Graphite nanoplatelets (GNPs)-the segregated ultra-high molecular weight polyethylene (UHMWPE)-based composites with hybrid filler-decorated with FeO were developed. Using X-ray diffraction and scanning electron microscopy, it was shown that the decorated component has the shape of separate granules, or their clusters were distributed evenly over the GNPs surface. The individual FeO nanoparticles are predominantly rounded, with diameters of approximately 20-60 nm. The use of GNPs/FeO as a filler leads to significant decreases in the percolation limit φc, 0.97 vol% vs. 0.56 vol% for GNPs/UHMWPE- and (GNPs/FeO)/UHMWPE segregated composite material (SCM), respectively. Modification of the GNP surface with FeO leads to an essential improvement in the electromagnetic interference shielding due to enhanced microwave absorption in the 26-37 GHz frequency range in its turn by abundant surface functional groups and lattice defects of GNPs/FeO nanoparticles.
PubMed: 38930178
DOI: 10.3390/ma17122808 -
Antioxidants (Basel, Switzerland) Jun 2024Pharmaceutical and personal care products (PPCPs) containing persistent and potentially hazardous substances have garnered attention for their ubiquitous presence in...
Pharmaceutical and personal care products (PPCPs) containing persistent and potentially hazardous substances have garnered attention for their ubiquitous presence in natural environments. This study investigated the impact of polyethylene glycol (PEG), a common PPCP component, on . Mussels were subjected to two PEG concentrations (E1: 0.1 mg/L and E2: 10 mg/L) over 14 days. Oxidative stress markers in both gills and digestive glands were evaluated; cytotoxicity assays were performed on haemolymph and digestive gland cells. Additionally, cell volume regulation (RVD assay) was investigated to assess physiological PEG-induced alterations. In the gills, PEG reduced superoxide dismutase (SOD) activity and increased lipid peroxidation (LPO) at E1. In the digestive gland, only LPO was influenced, while SOD activity and oxidatively modified proteins (OMPs) were unaltered. A significant decrease in cell viability was observed, particularly at E2. Additionally, the RVD assay revealed disruptions in the cells subjected to E2. These findings underscore the effects of PEG exposure on . They are open to further investigations to clarify the environmental implications of PPCPs and the possibility of exploring safer alternatives.
PubMed: 38929173
DOI: 10.3390/antiox13060734 -
Bioengineering (Basel, Switzerland) Jun 2024Ultra-high-molecular-weight polyethylene (UHMWPE) components for orthopedic implants have historically been integrated into metal backings by direct-compression molding...
Ultra-high-molecular-weight polyethylene (UHMWPE) components for orthopedic implants have historically been integrated into metal backings by direct-compression molding (DCM). However, metal backings are costly, stiffer than cortical bone, and may be associated with medical imaging distortion and metal release. Hybrid-manufactured DCM UHMWPE overmolded additively manufactured polyetheretherketone (PEEK) structural components could offer an alternative solution, but are yet to be explored. In this study, five different porous topologies (grid, triangular, honeycomb, octahedral, and gyroid) and three surface feature sizes (low, medium, and high) were implemented into the top surface of digital cylindrical specimens prior to being 3D printed in PEEK and then overmolded with UHMWPE. Separation forces were recorded as 1.97-3.86 kN, therefore matching and bettering the historical industry values (2-3 kN) recorded for DCM UHMWPE metal components. Infill topology affected failure mechanism (Type 1 or 2) and obtained separation forces, with shapes having greater sidewall numbers (honeycomb-60%) and interconnectivity (gyroid-30%) through their builds, tolerating higher transmitted forces. Surface feature size also had an impact on applied load, whereby those with low infill-%s generally recorded lower levels of performance vs. medium and high infill strategies. These preliminary findings suggest that hybrid-manufactured structural composites could replace metal backings and produce orthopedic implants with high-performing polymer-polymer interfaces.
PubMed: 38927852
DOI: 10.3390/bioengineering11060616 -
BMC Plant Biology Jun 2024Microplastic (MP) pollution in terrestrial ecosystems is gaining attention, but there is limited research on its effects on leafy vegetables when combined with heavy...
Microplastic (MP) pollution in terrestrial ecosystems is gaining attention, but there is limited research on its effects on leafy vegetables when combined with heavy metals. This study examines the impact of three MP types-polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS)-at concentrations of 0.02, 0.05, and 0.1% w/w, along with cadmium (Cd) and biochar (B), on germination, growth, nutrient absorption, and heavy metal uptake in red amaranth (Amaranthus tricolor L.). We found that different MP types and concentrations did not negatively affect germination parameters like germination rate, relative germination rate, germination vigor, relative germination vigor, and germination speed. However, they increased phytotoxicity and decreased stress tolerance compared to an untreated control (CK1). The presence of MPs, particularly the PS type, reduced phosphorus and potassium uptake while enhancing Cd uptake. For example, treatments PSCdB, PSCdB, and PSCdB increased Cd content in A. tricolor seedlings by 158%, 126%, and 44%, respectively, compared to the treatment CdB (CK2). Additionally, MP contamination led to reduced plant height, leaf dry matter content, and fresh and dry weights, indicating adverse effects on plant growth. Moreover, the presence of MPs increased bioconcentration factors and translocation factors for Cd, suggesting that MPs might act as carriers for heavy metal absorption in plants. On the positive side, the addition of biochar improved several root parameters, including root length, volume, surface area, and the number of root tips in the presence of MPs, indicating potential benefits for plant growth. Our study shows that the combination of MPs and Cd reduces plant growth and increases the risk of heavy metal contamination in food crops. Further research is needed to understand how different MP types and concentrations affect various plant species, which will aid in developing targeted mitigation strategies and in exploring the mechanisms through which MPs impact plant growth and heavy metal uptake. Finally, investigating the potential of biochar application in conjunction with other amendments in mitigating these effects could be key to addressing MP and heavy metal contamination in agricultural systems.
Topics: Amaranthus; Cadmium; Charcoal; Microplastics; Soil Pollutants; Germination; Nutrients; Seedlings
PubMed: 38926861
DOI: 10.1186/s12870-024-05312-0 -
Journal of Medical Case Reports Jun 2024Insulin autoantibody syndrome (IAS), or Hirata disease, is caused by high concentrations of insulin autoantibodies, which result in spontaneous, mainly post-prandial,...
BACKGROUND
Insulin autoantibody syndrome (IAS), or Hirata disease, is caused by high concentrations of insulin autoantibodies, which result in spontaneous, mainly post-prandial, hypoglycemic episodes. We report a case of a previously healthy 67-year-old man presenting with recurrent fasting hypoglycemia culminating in a diagnosis of insulin autoimmune syndrome linked to omeprazole and probably spices, namely, coriander, and ginger.
CASE PRESENTATION
A previously healthy 67-year-old Sinhalese man presented with recurrent syncopal attacks for 3 months, which were found to be hypoglycemic episodes. He experienced mainly fasting hypoglycemic attacks, at a frequency gradually increasing to daily attacks. His cardiovascular, respiratory, abdominal, and neurologic examinations were normal. He was found to have insulin levels > 6000 mU/L and a post-polyethylene glycol insulin recovery of less than 9.5%. Contrast-enhanced computed tomography of the pancreas was normal. The diagnosis of insulin autoantibody syndrome was confirmed by testing for the insulin autoantibody level, yielding a level of > 300 U/mL. With regard to a possible trigger, he had a history of omeprazole intake for 2 weeks, 4 weeks prior to the onset of symptoms. He also consumed an herbal supplement containing coriander and ginger extracts daily for a period of 1 year, approximately 2 years prior to the onset of hypoglycemic attacks. He was commenced on prednisolone 30 mg daily, and hypoglycemic episodes responded dramatically, and thus he was tapered off corticosteroids.
CONCLUSION
Omeprazole-induced insulin autoantibody syndrome is likely in this patient; however, the known hypoglycemic effects of coriander and ginger make it worthwhile to consider a possible association with insulin autoantibody syndrome. In addition, this case report highlights the need to consider insulin autoantibody syndrome even in patients presenting with fasting hypoglycemic attacks.
Topics: Humans; Male; Aged; Hypoglycemia; Insulin Antibodies; Omeprazole; Autoimmune Diseases; Insulin; Zingiber officinale; Syndrome; Autoantibodies
PubMed: 38926797
DOI: 10.1186/s13256-024-04616-x -
Scientific Reports Jun 2024Occupational radiation protection should be applied to the design of treatment rooms for various radiation therapy techniques, including BNCT, where escaping particles...
Occupational radiation protection should be applied to the design of treatment rooms for various radiation therapy techniques, including BNCT, where escaping particles from the beam port of the beam shaping assembly (BSA) may reach the walls or penetrate through the entrance door. The focus of the present study is to design an alternative shielding material, other than the conventional material of lead, that can be considered as the material used in the door and be able to effectively absorb the BSA neutrons which have slowed down to the thermal energy range of eV after passing through the walls and the maze of the room. To this aim, a thermal neutron shield, composed of polymer composite and polyethylene, has been simulated using the Geant4 Monte Carlo code. The neutron flux and dose values were predicted using an artificial neural network (ANN), eliminating the need for time-consuming Monte Carlo simulations in all possible suggestions. Additionally, this technique enables simultaneous optimization of the parameters involved, which is more effective than the traditional sequential and separate optimization process. The results indicated that the optimized shielding material, chosen through ANN calculations that determined the appropriate thickness and weight percent of its compositions, can decrease the dose behind the door to lower than the allowable limit for occupational exposure. The stability of ANN was tested by considering uncertainties with the Gaussian distributions of random numbers to the testing data. The results are promising as they indicate that ANNs could be used as a reliable tool for accurately predicting the dosimetric results, providing a drastically powerful alternative approach to the time-consuming Monte Carlo simulations.
PubMed: 38926477
DOI: 10.1038/s41598-024-65207-w -
Scientific Reports Jun 2024Stevia rebaudiana (stevia) is a plant in the Asteraceae that contains several biologically active compounds including the antidiabetic diterpene glycosides (e.g....
Stevia rebaudiana (stevia) is a plant in the Asteraceae that contains several biologically active compounds including the antidiabetic diterpene glycosides (e.g. stevioside, rebaudioside and dulcoside) that can serve as zero-calorie sugar alternatives. In this study, an elicitation strategy was applied using 5% polyethylene glycol (PEG), sodium chloride (NaCl; 50 and 100 mM) and gibberellic acid (2.0 and 4.0 mg/L GA) to investigate their effect on shoot morphogenesis, and the production of phenolics, flavonoids, total soluble sugars, proline and stevioside, as well as antioxidant activity, in shoot cultures of S. rebaudiana. Herewith, the media supplemented with 2 mg/L and 4 mg/L GA exhibited the highest shooting response (87% and 80%). The augmentation of lower concentrations of GA (2 mg/L) in combination with 6-benzylaminopurine (BAP) resulted in the maximum mean shoot length (11.1 cm). The addition of 100 mM NaCl salts to the media led to the highest observed total phenolics content (TPC; 4.11 mg/g-DW compared to the control 0.52 mg/g-DW), total flavonoids content (TFC; 1.26 mg/g-DW) and polyphenolics concentration (5.39 mg/g-DW) in shoots cultured. However, the maximum antioxidant activity (81.8%) was observed in shoots raised in media treated with 50 mM NaCl. The application of 2 mg/L of GA resulted in the highest accumulation of proline (0.99 μg/mL) as compared to controls (0.37 μg/mL). Maximum stevioside content (71 µL/mL) was observed in cultures supplemented with 100 mM NaCl and 5% PEG, followed by the 4 mg/L GA treatment (70 µL/mL) as compared to control (60 µL/mL). Positive correlation was observed between GA and stevioside content. Notably, these two compounds are derived from a shared biochemical pathway. These results suggest that elicitation is an effective option to enhance the accumulation of steviosides and other metabolites and provides the groundwork for future industrial scale production using bioreactors.
Topics: Stevia; Diterpenes, Kaurane; Glucosides; Plant Shoots; Gibberellins; Antioxidants; Secondary Metabolism; Flavonoids; Phenols; Sodium Chloride; Purines; Proline; Polyethylene Glycols; Benzyl Compounds
PubMed: 38926419
DOI: 10.1038/s41598-024-65483-6 -
PloS One 2024The Kyrenia Ship, found off the north coast of Cyprus, is a key vessel in the history of scientific underwater excavations and in the history of Greek shipbuilding. The...
The Kyrenia Ship, found off the north coast of Cyprus, is a key vessel in the history of scientific underwater excavations and in the history of Greek shipbuilding. The first volume of the site's final publication appeared in 2023 and provides detailed archaeological information tightly constraining the dating of the ship. A very specific date range is proposed: ca. 294-290 BCE, but is based on a less than certain reading of one coin recovered from the ship. While there is clear benefit to finding high-precision dates for the Kyrenia Ship and its rich assemblage using independent scientific dating (combined with Bayesian chronological modeling), efforts to do so proved more challenging and complex than initially anticipated. Strikingly, extensive radiocarbon dating on both wooden materials from the ship and on short-lived contents from the final use of the ship fail to offer dates using the IntCal20 calibration curve-the current Northern Hemisphere radiocarbon calibration curve at the time of writing-that correspond with the archaeological constraints. The issue rests with a segment of IntCal20 ca. 350-250 BCE reliant on legacy pre-AMS radiocarbon data. We therefore measured new known-age tree-ring samples 350-250 BCE, and, integrating another series of new known-age tree-ring data, we obtained a redefined and more accurate calibration record for the period 433-250 BCE. These new data permit a satisfactory dating solution for the ship and may even indicate a date that is a (very) few years more recent than current estimations. These new data in addition confirm and only very slightly modify the dating recently published for the Mazotos ship, another Greek merchant ship from the southern coast of Cyprus. Our work further investigated whether ship wood samples impregnated with a common preservative, polyethylene glycol (PEG), can be cleaned successfully, including a known-age test.
Topics: Radiometric Dating; Ships; Calibration; Archaeology; Cyprus; Carbon Radioisotopes; Bayes Theorem
PubMed: 38924012
DOI: 10.1371/journal.pone.0302645