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Molecules (Basel, Switzerland) Feb 2021For many antibacterial polymer fibres, especially for those with natural functional additives, the antibacterial response might not last over time. Moreover, the...
For many antibacterial polymer fibres, especially for those with natural functional additives, the antibacterial response might not last over time. Moreover, the mechanical performance of polymeric fibres degrades significantly during the intended operation, such as usage in textile and industrial filter applications. The degradation process and overall ageing can lead to emitted volatile organic compounds (VOCs). This work focused on the usage of pine rosin as natural antibacterial chemical and analysed the weathering of melt-spun polyethylene (PE) and poly lactic acid (PLA) polyfilaments. A selected copolymer surfactant, as an additional chemical, was studied to better integrate rosin with the molecular structure of the plastics. The results reveal that a high 20 w-% of rosin content can be obtained by surfactant addition in non-oriented PE and PLA melt-spun polyfilaments. According to the VOC analysis, interestingly, the total emissions from the melt-spun PE and PLA fibres were lower for rosin-modified (10 w-%) fibres and when analysed below 60 ℃. The PE fibres of the polyfilaments were found to be clearly more durable in terms of the entire weathering study, i.e., five weeks of ultraviolet radiation, thermal ageing and standard washing. The antibacterial response against Gram-positive by the rosin-containing fibres was determined to be at the same level (decrease of 3-5 logs cfu/mL) as when using 1.0 w-% of commercial silver-containing antimicrobial. For the PE polyfilaments with rosin (10 w-%), full killing response (decrease of 3-5 logs cfu/mL) remained after four weeks of accelerated ageing at 60 ℃.
Topics: Anti-Bacterial Agents; Microbial Sensitivity Tests; Pinus; Plastics; Polyesters; Polyethylene; Polymers; Resins, Plant; Silver; Staphylococcus aureus; Textiles; Volatile Organic Compounds
PubMed: 33562272
DOI: 10.3390/molecules26040876 -
Molecules (Basel, Switzerland) Sep 2020The water-resistant characteristics of ultraviolet crosslinked polyethylene (UV-XLPE) are investigated specially for the dependence on the hydrophilicities of auxiliary...
The water-resistant characteristics of ultraviolet crosslinked polyethylene (UV-XLPE) are investigated specially for the dependence on the hydrophilicities of auxiliary crosslinkers, which is significant to develop high-voltage insulating cable materials. As auxiliary crosslinking agents of polyethylene, triallyl isocyanurate (TAIC), trimethylolpropane trimethacrylate (TMPTMA), and N,N'-m-phenylenedimaleimide (HAV2) are individually adopted to prepared XLPE materials with the UV-initiation crosslinking technique, for the study of water-tree resistance through the accelerating aging experiments with water blade electrode. The stress-strain characteristics and dynamic viscoelastic properties of UV-XLPE are tested by the electronic tension machine and dynamic thermomechanical analyzer. Monte Carlo molecular simulation is used to calculate the interaction parameters and mixing energy of crosslinker/water binary systems to analyze the compatibility between water and crosslinker molecules. Water-tree experiments verify that XLPE-TAIC represents the highest ability to inhibit the growth of water-trees, while XLPE-HAV2 shows the lowest resistance to water-trees. The stress-strain and viscoelastic properties show that the concentration of molecular chains connecting the adjacent lamellae in amorphous phase of XLPE-HAV2 is significantly higher than that of XLPE-TAIC and XLPE-TMPTMA. The molecular simulation results demonstrate that TAIC/water and TMPTMA/water binary systems possess a higher hydrophilicity than that of HAV2/water, as manifested by their lower interaction parameters and mixing free energies. The auxiliary crosslinkers can not only increase the molecular density of amorphous polyethylene between lamellae to inhibit water-tree growth, but also prevent water molecules at insulation defects from agglomerating into micro-water beads by increasing the hydrophilicity of auxiliary crosslinkers, which will evidently reduce the damage of micro-water beads on the amorphous phase in UV-XLPE. The better compatibility of TAIC and water molecules is the dominant reason accounting for the excellent water resistance of XLPE-TAIC.
Topics: Algorithms; Cross-Linking Reagents; Hydrophobic and Hydrophilic Interactions; Models, Theoretical; Molecular Structure; Monte Carlo Method; Polyethylene; Trees; Ultraviolet Rays; Water
PubMed: 32927806
DOI: 10.3390/molecules25184147 -
Journal of ISAKOS : Joint Disorders &... Jun 2022Aseptic loosening is a major cause of failure for unicondylar knee arthroplasty (UKA). In total knee arthroplasty (TKA), early migration as measured with... (Meta-Analysis)
Meta-Analysis Review
IMPORTANCE
Aseptic loosening is a major cause of failure for unicondylar knee arthroplasty (UKA). In total knee arthroplasty (TKA), early migration as measured with radiostereometric analysis (RSA) is a strong predictor of late revision for aseptic loosening of the tibial component. Migration in the first two years provides information on the fixation of an implant. However, the migration pattern of UKAs has not been systematically determined, and it is unclear if the migration pattern of UKAs is similar to that of TKAs. Therefore, the present meta-analysis aims to evaluate the migration patterns of tibial components of UKAs.
EVIDENCE REVIEW
All RSA studies reporting on migration at two or more postoperative time-points following UKA were included. Pubmed, Web of Science, Cochrane, and Embase were searched up to April 2021. The risk of bias was assessed using the methodological score of the Assessment of Quality in Lower Limb Arthroplasty tool. All phases of the review were performed by two reviewers independently. A random-effects model was applied to pool the migration data.
FINDINGS
The literature search yielded 3,187 hits, of which ten studies were included, comprising 13 study groups and 381 UKAs. The majority of the early migration occurred in the first 6 months postoperatively followed by a period of very little migration, similar to what is reported for TKAs. The pooled mean migration expressed as the maximum total point motion of all UKAs at 3 months, 6 months, 1 year, and 2 years was 0.43 mm (95% CI 0.38-0.48), 0.54 mm (95% CI 0.40-0.67), 0.59 mm (95% CI 0.52-0.66), and 0.61 mm (95% CI 0.55-0.68), respectively. Migration at one year and two years was higher than migration of TKAs as reported in previous studies. All-polyethylene UKAs migrated more at one year (0.69 mm; 95% CI 0.58-0.80) than metal-backed UKAs (0.52 mm; 95% CI 0.46-0.58).
CONCLUSIONS AND RELEVANCE
The migration pattern of UKAs is comparable with that of TKAs in the first two years as both types of implants show initial migration in the first few months and very little migration thereafter. However, UKAs had higher migration at 1-year and 2-year follow-up.
Topics: Arthroplasty, Replacement, Knee; Humans; Knee Prosthesis; Polyethylene; Prosthesis Failure; Radiostereometric Analysis; Reoperation
PubMed: 36178392
DOI: 10.1016/j.jisako.2021.12.002 -
Proceedings of the National Academy of... Aug 2021Estimated millions of tons of plastic are dumped annually into oceans. Plastic has been produced only for 70 y, but the exponential rise of mass production leads to its...
Estimated millions of tons of plastic are dumped annually into oceans. Plastic has been produced only for 70 y, but the exponential rise of mass production leads to its widespread proliferation in all environments. As a consequence of their large abundance globally, microplastics are also found in many living organisms including humans. While the health impact of digested microplastics on living organisms is debatable, we reveal a physical mechanism of mechanical stretching of model cell lipid membranes induced by adsorbed micrometer-sized microplastic particles most commonly found in oceans. Combining experimental and theoretical approaches, we demonstrate that microplastic particles adsorbed on lipid membranes considerably increase membrane tension even at low particle concentrations. Each particle adsorbed at the membrane consumes surface area that is proportional to the contact area between particle and the membrane. Although lipid membranes are liquid and able to accommodate mechanical stress, the relaxation time is much slower than the rate of adsorption; thus, the cumulative effect from arriving microplastic particles to the membrane leads to the global reduction of the membrane area and increase of membrane tension. This, in turn, leads to a strong reduction of membrane lifetime. The effect of mechanical stretching of microplastics on living cells membranes was demonstrated by using the aspiration micropipette technique on red blood cells. The described mechanical stretching mechanism on lipid bilayers may provide better understanding of the impact of microplastic particles in living systems.
Topics: Lipids; Mechanical Phenomena; Membranes, Artificial; Microplastics; Particle Size; Polyethylene; Polymethyl Methacrylate; Polystyrenes
PubMed: 34326264
DOI: 10.1073/pnas.2104610118 -
Biosensors Nov 2022Terahertz (THz) wave is a good candidate for biological sample detection, because vibration and rotation energy levels of biomolecule are in THz band. However, the...
Terahertz (THz) wave is a good candidate for biological sample detection, because vibration and rotation energy levels of biomolecule are in THz band. However, the strong absorption of THz wave by water in biological samples hinders its development. In this paper, a method for direct detection of THz absorption spectra of L-arginine suspension was proposed by using a strong field THz radiation source combined with a polyethylene cell with micrometer thickness in a THz time-domain spectroscopy system. And the THz absorption spectrum of L-arginine solution was simulated by the density functional theory and the simulation result is in good agreement with the experimental results. Finally, the types of chemical bond interaction that cause the absorption peak are identified based on the experimental and simulation results. This work paves a way to investigate the THz absorption spectra and intramolecular interactions of aqueous biological samples.
Topics: Arginine; Computer Simulation; Water; Terahertz Spectroscopy; Polyethylene
PubMed: 36421147
DOI: 10.3390/bios12111029 -
PeerJ 2024Ants belonging to the (Formicidae: Hymenoptera) species are ubiquitous insects that are commonly associated with household settings in Pakistan. Packaged foodstuffs are...
Ants belonging to the (Formicidae: Hymenoptera) species are ubiquitous insects that are commonly associated with household settings in Pakistan. Packaged foodstuffs are easily destroyed by household ants when packaging is made with materials that have a high susceptibility. This study evaluated the susceptibility of three common flexible plastic packaging materials namely: opaque polyethylene, transparent polyethylene and polypropylene, which were each tested at thicknesses of 0.02 mm for their susceptibility against . Except opaque polyethylene which is only available at 0.02 mm thickness, both transparent polyethylene and polypropylene were tested at higher thickness of 0.04 mm and 0.06 mm also against . In order to simulate household settings, experiments were conducted at the faculty building of the agriculture and environment department of The Islamia University of Bahawalpur, Pakistan during summer vacations when the building was quiet. Different corners were selected near water sources for maximum exposure to the largest number of ants. Experimental cages used for the experiment were built with wood and 2 mm iron gauze to allow only ants to enter the cages. Daily activity of ants was used as an infestation source in cages. Experiments were run over three time spans of fifteen days each from June 20th 2022 to August 15th 2022. Results showed all packaging materials were susceptible against at the 0.02 mm thickness level. Polypropylene was susceptible at 0.04 mm thickness but resistant to ants at 0.06 mm thickness, whereas polyethylene was still susceptible to ants at the higher thickness of 0.06 mm. Correlation of packaging damage with weather factors showed that temperature had a positive relationship, while relative humidity had a negative association with attack. Overall correlation of packaging damage with packaging thickness showed packaging thickness was negatively associated with packaging damage from the ants. Because major cutting role is performed by the mandibles, we studied mandibles of ants and three frequent pests of packaged foodstuff namely , and . The results showed that ants had the largest mandible and frontal mandibular tooth lengths compared with the mandibles and frontal teeth of the common stored product pests, indicating household ants have a higher pest status for packaged foodstuffs compared to common stored product pests. Although the thickness of the flexible plastic packaging was a major factor against household ants, the study results recommend the use of polypropylene with a thickness of at least 0.06 mm as foodstuff packaging against household ants compared with polyethylene packaging, which was found to be susceptible to ants even at 0.06 mm thickness.
Topics: Animals; Ants; Polypropylenes; Polyethylene; Coleoptera
PubMed: 38435990
DOI: 10.7717/peerj.16782 -
European Journal of Hospital Pharmacy :... Nov 2022Topical resorcinol 15% is a self-treatment for painful hidradenitis suppurativa nodules and abscesses with good results in reducing pain and lesion duration. The aim of...
OBJECTIVES
Topical resorcinol 15% is a self-treatment for painful hidradenitis suppurativa nodules and abscesses with good results in reducing pain and lesion duration. The aim of this study is to establish a 15% topical resorcinol formula, to develop a physicochemical and microbiological stability study and to further determine the compounding shelf-life in different package conditions following the European Pharmacopoeia (Ph. Eur.) specifications.
METHODS
Physicochemical and microbiological stability studies of the formulation were conducted for 12 months at room temperature (25°C±2°C) in different package conditions: aluminium tubes (aluminium A7-99.7% varnish DF-6172), plastic tubes (low density polyethylene) and amber plastic containers (polyethylene terephthalate). High performance liquid chromatography (HPLC) was developed as a method of indicating the stability of the resorcinol formulation. A microbiological growth assay was also validated according to the Ph. Eur. Physical properties were inspected to determine parameters such as odour, colour, pH, emulsion phase and extensibility index and its evolution.
RESULTS
The HPLC method was validated according to the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. At day 365, visual inspection remained unchanged only for preparations packaged in aluminium tubes. The pH did not vary by more than 0.3 units in all conditions. The extensibility index decreased in the preparations packaged in plastic and amber plastic containers. HPLC analysis conducted over 1 year did not show a degradation greater than 7% of resorcinol in the preparation in plastic and aluminium packages. The ability of ATCC strains to grow in resorcinol formulation was confirmed under the suitability test. Resorcinol packed in aluminium tubes achieved microbiological stability at day 365.
CONCLUSIONS
Only the formulation package in aluminium tubes showed physicochemical and microbiological stability of resorcinol for 12 months at room temperature (25°C±2°C).
Topics: Humans; Aluminum; Amber; Drug Stability; Emulsions; Hidradenitis Suppurativa; Pain; Polyethylene; Polyethylene Terephthalates; Resorcinols; Chemical Phenomena
PubMed: 33328205
DOI: 10.1136/ejhpharm-2020-002534 -
Environmental Pollution (Barking, Essex... Sep 2022Airborne microplastics (MPs) have recently drawn the attention of the scientific community due to their possible human inhalation risk. Indoor environments are of...
Airborne microplastics (MPs) have recently drawn the attention of the scientific community due to their possible human inhalation risk. Indoor environments are of relevance as people spend about 90% of their time indoors. This study evaluated MPs concentrations in three indoor environments: houses, public transport and working places, which are representative of urban life. Sampling involved the collection of airborne particulate matter on nylon 20 μm pore size filters. Samples were first visually inspected, and particles were characterized (colour, length or area). Polymer identification was performed through μFTIR analysis. Working conditions were controlled to guarantee quality assurance and avoid background contamination. Limits of detection, recovery tests and repeatability were performed with home-made polyethylene (PE), polypropylene (PP), and polystyrene (PS) standards. The highest average MP concentrations were found in buses (17.3 ± 2.4 MPs/m) followed by 5.8 ± 1.9 MPs/m in subways, 4.8 ± 1.6 MPs/m in houses, and 4.2 ± 1.6 MPs/m in the workplaces. Polyamide, PA (51%), polyester PES (48%) and PP (1%) were the polymers identified and most common in personal care products and synthetic textiles. Most of these polymers were below 100 μm in size for both fibres (64 ± 8%) and fragments (78 ± 11%). The frequency of MP particles in our study decreased with increasing size, which points to their potential as an inhalation hazard.
Topics: Environmental Monitoring; Humans; Microplastics; Plastics; Polyethylene; Polymers
PubMed: 35803441
DOI: 10.1016/j.envpol.2022.119707 -
International Journal of Molecular... Mar 2023We describe here the fabrication, characterization, and properties of tough bioplastics made of a babassu oil-based acrylic polymer (PBBM), hemicellulose xylan grafted...
We describe here the fabrication, characterization, and properties of tough bioplastics made of a babassu oil-based acrylic polymer (PBBM), hemicellulose xylan grafted with PBBM chains, and carnauba wax (CW). The plastic was primarily designed to obtain bioderived materials that can replace low-density polyethylene (LDPE) in certain food packaging applications. To obtain plastic, the radical polymerization of an original babassu oil-based acrylic monomer (BBM) in the presence of xylan macromolecules modified with maleic anhydride (X-MA) was conducted. The polymerization resulted in a material (PBBM-X) mostly consisting of highly branched PBBM/X-MA macromolecules. PBBM-X has a glass transition of 42 °C, a storage modulus of 130 MPa (at 25 °C, RT), and a Young's modulus of 30 MPa at RT. To increase the moduli, we blended PBBM-X with carnauba wax, a natural material with a high modulus and a melting temperature of ~80 °C. It was found that PBBM-X is compatible with the wax, as evidenced by the alternation of the material's thermal transitions and the co-crystallization of BBM side alkyl fragments with CW. As a result, the PBBM-X/CW blend containing 40% of the wax had a storage modulus of 475 MPa (RT) and a Young's modulus of 248 MPa (RT), which is close to that of LDPE. As polyethylene, the PBBM-X and PBBM-X/CW bioplastics have the typical stress-strain behavior demonstrated by ductile (tough) plastics. However, the bioplastic's yield strength and elongation-at-yield are considerably lower than those of LDPE. We evaluated the moisture barrier properties of the PBBM-X/(40%)CW material and found that the bioplastic's water vapor permeability (WVP) is quite close to that of LDPE. Our bioderived material demonstrates a WVP that is comparable to polyethylene terephthalate and lower than the WVP of nylon and polystyrene. Taking into account the obtained results, the fabricated materials can be considered as polyethylene alternatives to provide sustainability in plastics production in the packaging areas where LDPE currently dominates.
Topics: Xylans; Polyethylene; Plastics; Food Packaging; Plant Oils; Biopolymers
PubMed: 37047076
DOI: 10.3390/ijms24076103 -
Journal of Applied Microbiology Oct 2022To determine the antimicrobial potency of a surface-anchored quaternary ammonium salt (SAQAS)-based biocide during in vitro wet and dry fomite assays and to determine...
AIMS
To determine the antimicrobial potency of a surface-anchored quaternary ammonium salt (SAQAS)-based biocide during in vitro wet and dry fomite assays and to determine the mechanism of killing bacteria on the surface.
METHODS AND RESULTS
Wet and dry fomite assays were established in vitro for a commercially available biocide (SAQAS-A) applied to glass and low-density polyethylene (LDPE) surfaces. Both wet and dry fomite tests showed the active killing of Gram-positive and Gram-negative bacteria but not endospores. Assays measuring membrane permeability (ATP and DNA release), bacterial membrane potential and bacterial ROS production were correlated with the time-to-kill profiles to show SAQAS-A activity in suspension and applied to a surface.
CONCLUSIONS
SAQAS-A is an effective biocide against model strains of vegetative bacteria. The killing mechanism for SAQAS-A observed minimal membrane depolarization, a surge in ROS production and assessment of membrane permeability supported the puncture of cells in both suspension and surface attachment, leading to cell death.
SIGNIFICANCE AND IMPACT OF THE STUDY
SAQAS represents effective surface biocides against single challenges with bacteria through a mechanical killing ability that supports real-world application if their durability can be demonstrated to maintain residual activity.
Topics: Adenosine Triphosphate; Anti-Bacterial Agents; Anti-Infective Agents; Bacteria; Disinfectants; Gram-Negative Bacteria; Gram-Positive Bacteria; Microbial Sensitivity Tests; Polyethylene; Quaternary Ammonium Compounds; Reactive Oxygen Species
PubMed: 35870145
DOI: 10.1111/jam.15729