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Researchers have long sought to predict the mechanical behavior of polyethylene from its microstructure. In particular, the yield strength and yield kinetics have been reported to be dependent on crystallinity and crystal thickness, but the relative importance of these two microstructural attributes has not been shown. In the present work, a series of microstructures was obtained through a combination of controlled quench rates from the melt and inclusion of various amounts of hexene comonomer. The yield strength for a wide range of strain-rates was linearly dependent on the crystallinity, and independent of crystal thickness (chain stem length), both measured by Raman spectroscopy. Similarly, yield kinetics described by a Ree-Eyring two-process stress activated model showed linear dependence on crystallinity and no dependence on crystal thickness. The results of the present work call into question models of yield kinetics dependent on screw dislocation nucleation, which depend on crystal thickness.

Predicting the successful preservation of posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) is an important step for preoperative planning to secure the satisfactory outcomes. We aimed to examine the preoperative factors predicting the successful preservation of the PCL in cruciate-retaining TKA and the outcome of sacrificing the PCL.In this retrospective study, we analyzed TKAs consecutively performed by a single surgeon between January 2019 and August 2021 who had been preoperatively planned to undergo implantation of cruciate-retaining (CR) prostheses. The outcome of the current study was whether the PCL was retained or sacrificed. Anterior-stabilized (AS) tibial bearings when the PCL was sacrificed as needed were used intraoperatively. Age, sex, body mass index (BMI), and preoperative diagnosis from the patients' medical records were obtained. The medial-lateral width of epicondyle (MLW), the medial posterior condyle height (MPCH), the lateral posterior condyle height (LPCH), the ratio of MLW and MPCH, the ratio of MLW and LPCH, the Insall-Salvati index, and the severity of the varus or valgus deformity were measured using preoperative radiographs. Univariate and multivariate regression were fitted to assess the association of these factors with the successful retention of PCL. To examine the influence of sacrifice of the PCL on the surgical procedure, the size of the tibial and femoral components, the thickness of the polyethylene insert, and the rate of patella replacement between the CR group and AS group were also compared using t tests or chi-square tests.Among 307 TKAs included, PCL was sacrificed with concurrent use of AS prostheses in 89 (29.0%) procedures. Knees with rheumatoid arthritis (P 0.01), lower Insall-Salvati index (P 0.01), and more severe varus deformity (P = 0.011) were at a higher risk of sacrificing the PCL intraoperatively. There was no significant difference in age, sex, BMI, MLW, MPCH, LPCH, ratio of MLW and MPCH, ratio of MLW and LPCH, size of the tibial and femoral components, or replacement of the patella between the CR and AS groups. Converting from CR to AS was associated with a higher risk of using a thicker polyethylene insert (P 0.01).Rheumatoid arthritis, lower Insall-Salvati index, and more severe varus deformity were associated with an increased risk of sacrificing the PCL in TKAs planned to undergo implantation CR prostheses. Converting to AS tibial bearing may result in a thicker polyethylene insert. These factors should be carefully considered for the appropriate selection of prosthesis type preoperatively.

The aquaculture environment, especially the culture ponds and aquaculture products, is considered to be an important reservoir of colistin resistance genes. However, systematic investigations of colistin resistance in Penaeus vannamei farming in different culture modes are scarce. In this study, a total of 93 non-duplicated samples were collected from P. vannamei farms in five cities in China from 2019 to 2021. The prevalence, antibiotic resistance and multilocus sequence typing (MLST) of colistin-resistant bacteria were measured and analysed. The results showed that among the 1601 isolates in P. vannamei and its environmental samples, the pollution of colistin-resistant bacteria was serious (the overall prevalence was 37.3% and 28.8%, respectively), regardless of the earthen pond or high-density polyethylene (HDPE) film-lined pond. Among 533 isolates, the prevalence of mobile colistin resistance (mcr) genes, mcr-1, was the highest (60%, 320/533), followed by mcr-4 (1.5%, 8/533), mcr-8 (0.9%, 5/533), mcr-10 (0.6%, 3/533) and mcr-7 (0.4%, 2/533). The prevalence of mcr-1 in earthen ponds was significantly higher than that in HDPE film-lined ponds (67.5% vs. 49.1%, p .001). The dominant strain carrying mcr-1 was Bacillus spp. (54.1%, 173/320), followed by Enterobacter spp. (8.1%, 26/320), Staphylococcus spp. (6.3%, 20/320) and Aeromonas spp. (5.3%, 17/320). The antibiotic resistance profiles of 173 Bacillus spp. varied among different sampling locations and culture types. These isolates were highly resistant to cefepime, ceftriaxone, trimethoprim-sulfamethoxazole and ceftiofur (45%), and multidrug-resistant isolates were common (62.4%, 108/173). Sequence type (ST) 26 (37/66, 56%) was found to be the most prevalent ST in mcr-1-positive Bacillus cereus isolated from the aquaculture environment. In summary, our study pointed out that it is necessary to continuously monitor antibiotic usage and its residues regardless of the pond types, especially with regard to critical drugs such as colistin.

We evaluated the precision and accuracy of multilaboratory measurements for determining freely dissolved concentrations (C

Trans-anethole (AN), which exhibits strong insect-repellent activity against Plodia interpunctella larvae, was applied on a polyethylene terephthalate (PET) film as an active packaging coating layer. All developed films at different concentrations (25%, 30%, 40%, and 50%) exhibited significant insect repellent activities. However, these films did not significantly differ from the control film in terms of color and transparency. In addition, the developed polypropylene (PP) and PET laminated films containing 25% AN (PP/AN25/PET) exhibited strong and continuous insect-repellent activity for up to 42 days. Finally, the developed film showed 2.86-fold stronger repellent activity than that of the control film when applied to the almond flake cereals packaging. These results suggest that PP/AN25/PET could be used as a potent insect-repelling packaging film in a realistic grain-packaging system. PRACTICAL APPLICATION: A PP/trans-anethole/PET film that exhibited good insect-repellent activity for 42 days was newly developed in this study. As it showed strong insect repellency, especially in almond flake cereals packaging, it is expected to have high potential as an insect-repelling grain-packaging film.

Research into Piscirickettsia salmonis biofilms on materials commonly used in salmon farming is crucial for understanding its persistence and virulence. We used the CDC Biofilm Reactor to investigate P. salmonis (LF-89 and EM-90) biofilm formation on Nylon, Stainless steel (316L), Polycarbonate and High-Density Polyethylene (HDPE) surfaces. After 144 h of biofilm visualization by scanning confocal laser microscopy under batch growth conditions, Nylon coupons generated the greatest biofilm formation and coverage compared to Stainless steel (316L), Polycarbonate and HDPE. Additionally, P. salmonis biofilm formation on Nylon was significantly greater (p ≤ .01) than Stainless steel (316L), Polycarbonate and HDPE at 288 h. We used Nylon coupons to determine the kinetic parameters of the planktonic and biofilm phases of P. salmonis. The two strains had similar latencies in the planktonic phase; however, LF-89 maximum growth was 2.5 orders of magnitude higher (Log cell ml

The aim of the present study was to evaluate how much reduction in acetabular liner thickness could be tribologically acceptable in metal-on-vitamin-E diffused highly crosslinked ultra-high molecular weight polyethylene (Vit-E XLPE) bearings for total hip arthroplasty. We tested thick- (10.3 mm), moderate- (6.3 mm), and thin- (4.3 mm) Vit-E XLPE liners coupled with 28-mm cobalt-chromium femoral heads on a hip simulator to 5 million cycles, and peak contact stress was predicted based on mathematical modeling. Wear damage was also evaluated in terms of surface topology and morphology. Wear simulation demonstrated that the 2-4 mm thickness reduction (6.3 → 4.3 mm and 10.3 → 6.3 mm) did not significantly affect the wear rate for Vit-E XLPE liner, whereas 6-mm reduction (10.3 → 4.3 mm) significantly increased liner wear (by 309%) and head roughness (by 415%). This effect was attributed to a contact stress increase (by 24-41%). However, the wear rates for all thicknesses tested were much lower than those previously reported for thicker non-crosslinked materials. The original crystalline morphology was maintained in all liners after wear. Our results suggest that the 2-4 mm thickness reduction may be tribologically acceptable in Vit-E XLPE liners. However, more severe and longer term simulations are necessary to determine a minimum acceptable thickness.

To explore the feasibility and clinical efficacy of a modified medial collateral ligament indentation technique in total knee arthroplasty (TKA) with severe type II valgus deformity.Consecutive patients with Krackow type II valgus deformity20° who underwent a primary unilateral TKA between May 2008 and June 2017 were studied retrospectively. A medial collateral ligament indentation technique was performed in 20 patients (MCLI group), and 23 patients received the routine lateral structures release technique (LSR group). Radiological parameters, such as the valgus angle (VA), and functional outcomes including the use of constraint implants, Knee Society Score (KSS), Knee Society Function score (KSF), and thickness of the polyethylene insert were compared between the two groups.A total of 43 consecutive patients had a minimum 2-year follow-up. The preoperative VA was comparable between the MCLI (23.5° ± 5.8°) and LSR groups (21.3° ± 3.2°, P = 0.134), as was the postoperative VA (1.1° ± 2.1° and 2.5° ± 3.0°, respectively, P = 0.084). The mean KSS and KSF scores in the MCLI group were 30.2 ± 4.8 and 38.8 ± 4.8, respectively, before surgery, and they increased to 91.3 ± 2.6 and 86.5 ± 2.4 at the last follow-up. The scores in the LSR group were 31.5 ± 7.5 and 36.5 ± 7.8 before surgery and 92.4 ± 3.5 and 88.5 ± 3.6 at the last follow-up. While no statistically significant differences in pre- or postoperative functional scores were found between the two groups, the MCLI group had thinner polyethylene inserts (9.5 ± 1.1 mm vs 12.9 ± 1.5 mm) and less use of constrained condylar inserts (15% vs 69.6%). During follow-up, the MCLI group had fewer complications.A modified MCLI technique can achieve good outcomes in TKA with type II valgus deformity of20°. It can maintain a normal joint line level, reduce the use of constrained condylar knee prostheses, and is a reliable choice for severe genu valgum.

We aimed to explore a novel method for ear reconstruction stent remodeling to achieve high patient satisfactory outcomes.This study is a retrospective review of patients with congenital or acquired ear defects who were prepared for one-stage ear reconstruction with high-density porous polyethylene stent between May 2020 and May 2021. A standardized data collection template was used to collect related variables. In this study, the detailed reconstruction surgery process is carefully described, and the postoperative healing process of the ear reconstruction was closely observed.A total of 26 patients for one-stage ear reconstruction with high-density porous polyethylene stent or autogenous costal cartilage scaffolds were admitted to the department of plastic surgery in our hospital between May 2020 and May 2021. All patients were followed until their ear flaps were alive and details of the ear shape were revealed. The patients with new remolding method were no severe complications and only a patient had stent exposure, and were highly satisfied with both appearance and function.The application of novel remodeling method is a promising way for ear reconstruction stent shaping with little postoperative complication and excellent postoperative patient satisfaction.

Crosslinking substantially reduces the wear of ultra-high molecular weight polyethylene (UHMWPE) used in total hip arthroplasty (THA) but some reports have indicated that first generation liners manufactured without antioxidants may be vulnerable to in vivo oxidation. This study evaluated maximum oxidation using Fourier transform infrared spectroscopy per ASTM F2102-06

Metal on polyethylene (MoP) total hip arthroplasty prostheses are known to release metal debris. Basic science studies suggest that metal implants induce a pro-inflammatory response that ultimately chemoattracts leukocytes including macrophages and neutrophils to the surgical site. This raises concern of higher risk of infection with these prosthesis through the "trojan horse" mechanism by which neutrophils and macrophages transport intracellular pathogens from a remote site. This study compared the infection occurrence between MoP and ceramic on polyethylene (CoP) implants to determine if a higher infection rate in MoP is present. We reviewed a consecutive series of 6,052 CoP and 4,550 MoP primary total hip arthroplasty (THA) patients from 2015-2019. The occurrence of periprosthetic joint infection at two years was defined according to the 2018 ICM definition. Statistical analysis consisted of descriptive statistics, univariate analysis, and regression modeling. When compared to CoP, MoP patients were older, included more females, had a higher body mass index, and more commonly affected by comorbidities according to Elixhauser score. Total revisions were higher in the MoP group (3.19% vs 2.41%) The absolute incidence of PJI was higher in MoP (2.40% vs 1.64%). When we adjusted for confounding factors, MoP was found independently associated with a higher PJI risk. Despite MoP and CoP both being widely used for primary THA, we found a higher incidence of PJI in MoP patients. The association remained significant when controlled for possible confounders. We hypothesize that leukocyte recruitment to these implants may play a role and should be further investigated. This article is protected by copyright. All rights reserved.

Polyethylene materials are highly important polymers which are produced in the largest volume among all plastics. Due to the chemical inert property of saturated carbon-carbon bonds, the degradation of polyethylene is extremely challenging, which prevents them from efficient chemical recycling. Installing functional groups in the main chain of polyethylenes may facilitate the degradation and following chemical recycling of polyethylene materials. Here we report a highly selective approach for the synthesis of high-density polyethylenes bearing isolated in-chain carbonyls. Linear high-molecular weight polyethylene chains are synthesized via the palladium catalyzed copolymerization of ethylene with metal carbonyls. Different from traditional ethylene/CO copolymerization reactions, excellent non-alternating selectivity has been achieved. While the properties of polyethylene have been retained in the copolymer, faster degradation compared with that of polyethylene was observed upon UV light irradiation. The synthesized materials may therefore serve as more environmentally friendly alternative plastics than traditional polyethylene materials.

Heavy metals and microplastics are two types of general contaminants that can cause significant damage to water systems and organisms. However, the interaction of heavy metal ions with microplastic in aquatic systems received less attention compared with that of organic contaminants. This study aims to explore the interaction of copper (II) ions with microplastic (polyethylene) in aquatic systems. The adsorption experiments were performed by varying several operational parameters including equilibrium pH, initial Cu (II) concentrations, and contact times. The microplastic was characterized using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared. The results confirmed the porous nature of the microplastic surface and the existence of various binding sites. The maximum Cu (II) uptake by microplastic was recorded as 1.23 mg/g at pH 5, according to the Langmuir adsorption isotherm. The experimental isotherm data exhibited a good fit to the Toth model, followed by the Langmuir and Freundlich equations, according to the correlation coefficient and %error values. The pseudo-first kinetics equation showed a better fit to copper (II) kinetics data compared with the pseudo-second kinetics equation. Elution of copper (II) ions from copper (II)-loaded microplastic was attempted using several elutants, and the results indicated that 0.01 M HNO

Techniques for vacuum UV (VUV) photo-oxidation of materials, using emission from plasmas with wavelengths shorter than 180 nm, are reviewed focusing on adhesion improvement for polymers, such as, fluoropolymers, membranes used in fuel cells, polyimides, polyethylene, and polystyrene. Future adhesion research is proposed for VUV photo-oxidized polypropylene, poly(ethylene terephthalate), poly(ethylene 2,6-naphthalate), cyclo-olefin polymers, polybenzimidazole, and sustainable polymers.

One promising approach to recycle multicomponent plastic waste (e. g., multilayer plastic films) is selective dissolution. Selective dissolution is a solvent-mediated process in which differences in polymer solubility in a carefully chosen solvent system are exploited to recover a target polymer. Here, a computational approach was developed that rapidly predicts temperature-dependent polymer solubilities to guide the design of solvent systems for solvent-mediated polymer recycling. Polymer conformations were obtained from molecular dynamics simulations by modeling the polymer as a short oligomer and then used as input to the conductor-like screening model for real solvents (COSMO-RS) for solubility predictions. Using polyethylene (PE) and ethylene vinyl alcohol (EVOH) as representative polymers, the effect of simulation parameters was systematically studied, and predicted solubilities were found to be in good agreement with experimental measurements. The applicability of the approach was demonstrated by identifying selective solvents for PE and EVOH dissolution from a library of 524 solvents.

A new generation of ceramic on ceramic (BIOLOX ®delta) bearings has emerged more than 10 years ago proving a high resistance to wear and good clinical results. However, biological reactions to wear debris, particularly the nanoparticles, need to be evaluated. The first originality of this study is to start from real wear particles obtained by the hip walking simulator (CERsim). These particles were compared with particles obtained by usual methods to assess the biocompatibility of materials: press machine (CERpress). Two ranges of ceramic particles were thus observed: ceramic particles with micron (intergranular fractures) and nano sizes (intragranular fractures), and characterized compared to ultra-high molecular weight polyethylene (UHMWPE). The second originality of this work is to assess the cellular reaction using the primary joint chondrocyte cultures simulating the osteogenesis process and not the cell lines, which are used to simulate the biological reaction of osteolysis. The first results showed a significant difference in cell viability between the cells in contact with particles from the walking simulator and those obtained with the press machine. On the other hand, it was found that the way of extraction of the particles from the lubricant could significantly affect the biological reaction. More interestingly, nano-sized ceramic particles showed a significant impact on the secretion of functional inflammatory mediators, agreeing with recent results in vivo. These novel methods of characterizing the osteogenic impact of UHMWPE and ceramic wear debris can complement the conventional expertise method focusing previously on the osteolysis aspect.

Low-density polyethylene (LDPE) is ubiquitous in the packaging industry owing to its flexibility, toughness, and low cost. However, it is typically contaminated with other materials, seriously limiting options for mechanical recycling. Interest in chemical recycling techniques such as pyrolysis and hydrothermal liquefaction is growing, but most of these processes face technoeconomic challenges that have limited commercial deployment. This study concerns a hybrid chemomechanical approach using reactive twin-screw extrusion (TSE) for tailoring the molecular weight and chain structure of reclaimed LDPE. Two types of zeolite catalysts at several loading levels are evaluated over a range of processing conditions. Structural, thermal, and rheological properties of the extruded samples are investigated and compared to virgin LDPE and LDPE extruded without the catalyst. NMR spectroscopy is used to investigate changes in the structure of the polymer. LDPE extruded with microporous Y zeolite shows lower degradation temperature and increased short chain branching. Mesoporous MCM-41 also induces increased branching but has no effect on the degradation temperature. The theoretical mechanical energy input for the chemical modification is calculated by using process modeling. The demonstrated hybrid reactive extrusion process provides a potential low-cost, simple approach for repurposing LDPE-based flexible packaging as coatings and adhesives.

The practical synthesis of polar-functionalized polyolefins using transition-metal-catalyzed copolymerization of olefins with polar monomers is a challenge; the use of heterogeneous catalysts is little explored. Herein, we report the synthesis of heterogeneous naphthoquinone-based nickel (Ni/SiO2 ) and palladium (Pd/SiO2 ) catalysts through hydrogen bonding interactions of the ligands with the silica surface. Ni/SiO2 exhibits high activities (up to 2.65×106 g mol-1 h-1 ) during the copolymerization of ethylene with 5-hexene-1-yl-acetate, affording high-molecular-weight (Mn up to 630 000) polar-functionalized semicrystalline polyethylene (comonomer incorporation up to 2.8 mol %), along with great morphology control. The resulting copolymers possess improved surface properties and great mechanical properties. Pd/SiO2 can mediate ethylene copolymerization with polar monomers with moderate activity to produce high-molecular-weight copolymers with tunable comonomer incorporation.

Cone calorimeter and controlled atmosphere cone calorimeter experiments were conducted on various samples. The intent of the tests was to examine the behavior of uniform and composite samples in a range of thicknesses, irradiances, and oxygen concentrations. Single, uniform layers of acrylonitrile butadiene styrene (ABS) were compared to a composite mix, comprising of ABS with a surface layer of cardboard and a secondary layer of polyethylene bubble wrap (intended to represent a potential storage arrangement). The horizontal samples have been tested at irradiances of 25 and 50 kW/m2 and oxygen concentrations of 20.95%, 17%, and 15% to examine a range of significant variables. Results for the uniform arrangement indicated various correlations, previously observed in the works of others, such as the relationships typically described between applied heat flux, ignitability, heat release rate and the effect of the introduction of hypoxic conditions. However, results were shown to change significantly when samples were arranged to feature composite layers. A hypothesized cause of the behavioral change, namely the soot and char residual introduced from the incomplete combustion of the cardboard layer, highlights further important variables that require consideration in material testing under hypoxic conditions. Such variables, namely specific material behaviors and sample orientation, must be sufficiently captured in the design methodologies of systems reliant upon the introduction of hypoxic conditions. It is concluded that sufficiently capturing a wider range of variables in burning materials under hypoxic conditions will introduce further design resilience and help optimize fire protection/prevention methods. (Less)

Measurements of wear resistance and metal ion release are important for designing bearing couples or interfaces in total hip arthroplasty (THA). In this study, we investigated wear resistance and metal ion release of surface-modified metal-free all-polymer hip bearings, such as poly(ether-ether-ketone), (PEEK) on cross-linked polyethylene (PEEK-on-CLPE), with a hydrated gel-like surface layer, to propose an improved alternative to the conventional materials used to design THA bearings. The PEEK surface resulted in less metal ion release than the cobalt-chromium-molybdenum (Co-Cr-Mo) alloy surface owing to the lack of metal. The PEEK-on-CLPE bearing (6.33 mg/106 cycles) had lower wear (rate) than the bearing with Co-Cr-Mo alloy-on-CLPE (10.47 mg/106 cycles) under controlled laboratory conditions; the wear performance of the all-polymer hip bearings was further improved with hemi- or both-surface modified with a hydrated poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer (3.74 and 3.06 mg/106 cycles, respectively). The PMPC-grafted interface of PEEK-on-CLPE will be especially suitable for THA candidates. This study is of key importance for the design of lifelong THA and a better understanding of the limitations resulting from using PEEK. Further studies are necessary to evaluate the possibility of using this material in artificial hips.

Eco‐friendly composite materials have received more attention in recent years, and research has shown that biostructures have great potential as a solution to meet the needs of sustainability in product design and potential food packaging. In this study, the mechanical, thermal, morphological, water absorption properties and water vapor permeability of bio‐composites based on polyethylene and sour cherry shell powder (SCS) (0% –7.5%) have been investigated. It was observed that 2.5% of sour cherry shell increased elastic modulus and tensile strength and improved mechanical properties. Composites without adding sour cherry shell show 1.28% water absorption. Decreased water absorption was observed for treated composites containing 2.5% of sour cherry shell, and its amount was 1.26%. The presence of sour cherry shell increased the bio‐composite resistance to moisture absorption, but the addition had little effect on the thermal process properties of polyethylene. Vapor permeability in sour cherry shell / polyethylene bio‐composites, which was a significant difference between samples with sour cherry shells (2.5%–7.5%) and samples without sour cherry shells. Results indicated that polyethylene/sour cherry shell composites could be used to replace polyethylene in application such as stretch film, shrink film, and bags of fruit., Polyethylene/sour cherry shell bio‐composites could be used to replace polyethylene in application such as stretch film, shrink film and bags of fruit. valorization of fruits waste and increasing biodegradability and environmental issues was the objectives of this research.

The impact of a small amount of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) on the thermomechanical and electrical properties of blends comprising low-density polyethylene (LDPE) and isotactic polypropylene (PP) is investigated. SEBS is found to assemble at the PP:LDPE interface as well as within isolated PP domains. The addition of 10 wt% SEBS significantly increases the storage modulus between the melting temperatures of the two polyolefins, 110 and 160°C, and results in improved resistance to creep during both tensile deformation as well as compression. Furthermore, the ternary blends display a very low direct-current (DC) conductivity as low as 3.4 × 10 S m at 70°C and 30 kV mm , which is considerably lower than values measured for neat LDPE. The here presented type of ternary blend shows potential as an insulation material for high-voltage direct current power cables.