SciCombinator

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Concept: Polyethylene

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The occurrence of microplastics (MPs) in saltwater bodies is relatively well studied, but nothing is known about their presence in most of the commercial salts that are widely consumed by humans across the globe. Here, we extracted MP-like particles larger than 149 μm from 17 salt brands originating from 8 different countries followed by the identification of their polymer composition using micro-Raman spectroscopy. Microplastics were absent in one brand while others contained between 1 to 10 MPs/Kg of salt. Out of the 72 extracted particles, 41.6% were plastic polymers, 23.6% were pigments, 5.50% were amorphous carbon, and 29.1% remained unidentified. The particle size (mean ± SD) was 515 ± 171 μm. The most common plastic polymers were polypropylene (40.0%) and polyethylene (33.3%). Fragments were the primary form of MPs (63.8%) followed by filaments (25.6%) and films (10.6%). According to our results, the low level of anthropogenic particles intake from the salts (maximum 37 particles per individual per annum) warrants negligible health impacts. However, to better understand the health risks associated with salt consumption, further development in extraction protocols are needed to isolate anthropogenic particles smaller than 149 μm.

Concepts: Water, Polymer, Carbon, Plastic, Polypropylene, Polyethylene, Plasticizer, Polyethylene terephthalate

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There are several well-described causes of a painful mass following total hip arthroplasty including polyethylene and metal wear debris, infection, expanding hematoma, dislocation, and synovial cysts. In addition to causing pain, these lesions, when large enough, may cause neurologic and vascular compromise. Rapid growth of the mass may clinically and radiographically resemble a sarcoma. Here, we report a case of a large painful hip mass which developed after total hip arthroplasty. The well-circumscribed mass was overlying and extending into the hip joint containing thousands of highly organized fibrin-containing “rice bodies”. To our knowledge, this is the first report of a large, highly organized (rice-body-containing) cyst complicating total hip arthroplasty.

Concepts: Causality, Hip replacement, Hip, Pelvis, Orthopedic surgery, Joint replacement, Synovial joint, Polyethylene

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Plastics are synthetic polymers derived from fossil oil and largely resistant to biodegradation. Polyethylene (PE) and polypropylene (PP) represent ∼92% of total plastic production. PE is largely utilized in packaging, representing ∼40% of total demand for plastic products (www.plasticseurope.org) with over a trillion plastic bags used every year [1]. Plastic production has increased exponentially in the past 50 years (Figure S1A in Supplemental Information, published with this article online). In the 27 EU countries plus Norway and Switzerland up to 38% of plastic is discarded in landfills, with the rest utilized for recycling (26%) and energy recovery (36%) via combustion (www.plasticseurope.org), carrying a heavy environmental impact. Therefore, new solutions for plastic degradation are urgently needed. We report the fast bio-degradation of PE by larvae of the wax moth Galleria mellonella, producing ethylene glycol.

Concepts: Petroleum, Polymer, Plastic, Polypropylene, Lepidoptera, Polyethylene, Moth, Polyethylene terephthalate

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Ion imprinting has become one of the fast-growing technologies that have gained a lot of attention recently especially in the area of materials science. One of them is called the ion-imprinted polymers (IIPs). The IIPs are synthesized on the principles of enzyme phenomenon whereby a polymer is altered by a polymerization that takes place in the presence of a template that will be later removed to create cavities that will recognize only the analyte of interest. This specific and selective affinity for the target species decreases the chances of competition with other different types of ions. The imprinting technique started with the discovery of the bulk polymerization method where by the monomer, initiator, crosslinker, and template are mixed together and allowed to polymerize, and then the resulting polymer is ground and sieved to get particles with sizes suitable for the polymer’s application. The IIPs have got some attractive qualities for use in environmental applications which include their stability and inexpensiveness and have a wide range of synthesis options with each suiting a certain unique application. Apart from environmental work, IIPs have applications in many other areas such as in membranes, in drug delivery, and in biosensors as alternatives to antibodies just to mention a few. This review focuses on the synthesis, types of imprinting, characterization, and applications of IIPs.

Concepts: Polymer, Polymer chemistry, Sol-gel, Monomer, Materials science, Polyethylene, Branching, Polymerization

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The mechanism of crack initiation from a clinically relevant notch is not well-understood for crosslinked ultra high molecular weight polyethylene (UHMWPE) used in total joint replacement components. Static mode driving forces, rather than the cyclic mode conditions typically associated with fatigue processes, have been shown to drive crack propagation in this material. Thus, in this study, crack initiation in a notched specimen under a static load was investigated. A video microscope was used to monitor the notch surface of the specimen and crack initiation time was measured from the video by identifying the onset of crack initiation at the notch. Crack initiation was considered using a viscoelastic fracture theory. It was found that the mechanism of crack initiation involved both single layer and a distributed multi-layer phenomenon and that multi-layer crack initiation delayed the crack initiation time for all loading conditions examined. The findings of this study support that the viscoelastic fracture theory governs fracture mechanics in crosslinked UHMWPE. The findings also support that crack initiation from a notch in UHMWPE is a more complex phenomenon than treated by traditional fracture theories for polymers.

Concepts: Fracture, Physics, Shock, Fracture mechanics, Fractography, Fatigue, Polyethylene, Fracture toughness

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Brushite (dicalcium phosphate dihydrate, DCPD) cement, owing to its high solubility in physiological condition and ability to guide new bone formation, is widely used to treat bone defects. In the present study, we have evaluated the effects of poly ethylene glycol (PEG) addition on the setting time, compressive strength and in vitro biocompatibility of brushite cement. The brushite cements were prepared by mixing β-tricalcium phosphate [β-TCP, Ca(3)(PO(4))(2)] and monocalcium phosphate monohydrate [MCPM, Ca(H(2)PO(4))(2). H(2)O]. PEG was introduced at 2.0 and 5.0 wt% with the liquid. Introduction of PEG resulted in marginal increase in both initial and final setting time; however, significantly affected the compressive strength. Effects of PEG incorporation on in vitro biocompatibility of brushite cements were studied by using human fetal osteoblast cells (hFOB) cells. Field emission scanning electron microscope (FESEM) images and immunohistochemical analysis indicated that pure and PEG incorporated brushite cement facilitates cell adhesion, proliferation and differentiation. Fewer cells expressed vinculin protein with increased PEG content in the cement. Cell proliferation was found to decrease with increased PEG concentration while the cell differentiation increased with PEG content. Our results provide a better understanding of in vitro biocompatibility of PEG added brushite cements that can be used to customize the cement compositions based on application need.

Concepts: DNA, Electron, Gene expression, Scanning electron microscope, Ethylene glycol, Polyethylene, Ethylene, Dicalcium phosphate

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INTRODUCTION: Hyperfibrinolysis is observed during and immediately after major orthopedic surgery. The kinetics and duration of this phase should be defined to adjust the duration of antifibrinolytic treatment with tranexamic acid (TXA). OBJECTIVE: We aimed to quantify the duration of postoperative fibrinolysis and to assess the biological impact of TXA administration. MATERIALS AND METHODS: Fourteen patients undergoing total hip replacement (THR) and 10 patients undergoing total knee replacement (TKR) with tourniquet were included in an observational, prospective, single-center study. Among these patients, 7 THR patients and 5 TKR patients received TXA (15mg/kg IV intraoperatively, followed by continuous infusion of 15mg/kg/h until end of surgery, then every 4hours until 16±2hours after surgery). D-dimers, euglobulin lysis time (ELT), and thrombin generation time (TGT) were measured prior to surgery as well as 6, 18 and 24hours (H) after. RESULTS: No significant difference in ELT was observed between the groups. In contrast, D-dimers significantly increased postoperatively in patients not treated with TXA (p<0.001), while such an increase was prevented in patients receiving TXA, as measured at H0, H6, H18 and H24 after THR, and at H6 and H18 after TKR (p<0.001). No significant between-group change in TGT, was observed (peak thrombin and endogenous thrombin potential) all along the study. CONCLUSION: This study shows that fibrinolysis peaked 6hours after end of surgery and maintained about 18hours after surgery, as evidenced by an increase in D-dimers. When administered for up to 16±2hours after surgery, TXA reduced postoperative fibrinolysis.

Concepts: Hip replacement, Orthopedic surgery, Joint replacement, Knee replacement, Polyethylene, Antifibrinolytic, John Charnley

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Nonvolatile resistive switching has been observed for the first time in CdSe nanowire (NW)/Au Schottky barrier diodes, where a Schottky contact electrode and an Ohmic contact electrode were formed at the Au/CdSe NW and CdSe NW/In interfaces, respectively. The CdSe NWs Schottky devices were found to possess multibit storage ability in an individual nanowire, and exhibited excellent memory characteristics, with a resistance on/off ratio exceeding four orders of magnitude, a long retention time of over 10(4) s and a lower operating voltage of 2 V. By replacing the SiO(2)/Si substrate with a poly ethylene terephthalate substrate, flexible and transparent memory devices with superior stability under strain were realized. The resistive switching of CdSe NW/Au Schottky devices is understood by electron trapping and detrapping in the interfacial oxide layer. Our findings provide a viable way to create new functional high-density nonvolatile multibit memory devices compatible with simple processing techniques for normal one-dimensional nanomaterials.

Concepts: Solar cell, Diode, Polyethylene, Ohm's law, P-n junction, Schottky barrier, Schottky diode, Ohmic contact

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The influence of PBR composition [clear polyurethane (PolyU) vs. clear linear low-density polyethylene (LLDPE) (top) and black opaque high-density polyethylene (bottom)] and shape (rectangular vs. tubular) on biofouling and the influence of biofouling on algae productivity were investigated. In 9-week experiments, PBR biofouling was dominated by pennate diatoms and clear plastics developed macroalgae. LLDPE exhibited lower photosynthetic-active-radiation (PAR) light transmittance than PolyU before biofouling, but higher transmittance afterwards. Both rectangular and tubular LLDPE PBRs accumulated biofouling predominantly along their wetted edges. For a tubular LLDPE PBR after 12weeks of biofouling, the correlation between biomass, percent surface coverage, and PAR transmittance was complex, but in general biomass inversely correlated with transmittance. Wrapping segments of this biofouled LLDPE around an algae culture reduced CO2 and NH3-N utilization, indicating that external biofouling must be controlled.

Concepts: Algae, Photosynthesis, Polyethylene, Plastics, Linear low-density polyethylene, High-density polyethylene, Low-density polyethylene, Polyolefins

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We asked whether cementless total hip arthroplasties that made use of alumina-on-highly cross-linked polyethylene bearings would improve hip score and functional activity and reduce the prevalence of polyethylene wear, osteolysis, and aseptic loosening.

Concepts: Hip replacement, Orthopedic surgery, Polyethylene