Polyethylene Surface Research Articles

Surface wear in a custom manufactured temporomandibular joint prosthesis.

The wear of a novel temporomandibular joint (TMJ) prosthesis was evaluated in an animal model. The prosthesis consisted of an additively manufactured titanium alloy (Ti6Al4V) mandibular condyle and glenoid fossa created through selective laser melting, with a machined vitamin E‐enriched ultra‐high molecular weight polyethylene (UHMWPE) surface attached to the fossa. Thirteen TMJ prosthesis were implanted in sheep, six of which had condylar heads coated with HadSat® diamond‐like carbon (H‐DLC). Euthanasia took place after 288 days, equaling 22 years of human mastication. Linear and volumetric wear analysis of the fossa was performed by optical scanning. The condylar head surfaces were assessed by scanning electron and confocal laser microscopy. The average linear UHMWPE wear, when combined with the coated condyle, was 0.67 ± 0.28 mm (range: 0.34–1.15 mm), not significantly differing (p = .3765, t‐test) from the non‐coated combination average (0.88 ± 0.41 mm; range: 0.28–1.48 mm). The respective mean volumetric wear volumes were 25.29 ± 11.43 mm3 and 45.85 ± 22.01 mm3, not significantly differing (p = .1448, t‐test). Analysis of the coated condylar surface produced a mean Ra of 0.12 ± 0.04 μm and Sa of 0.69 ± 0.07 μm. The non‐coated condylar surface measured a mean Ra of 0.28 ± 0.17 μm and Sa of 2.40 ± 2.08 μm. Both Sa (p = .0083, Mann–Whitney U test) and Ra (p = .0182, Mann–Whitney U test), differed significantly. The prosthesis exhibits acceptable wear resistance and addition of the H‐DLC‐coating significantly improved long‐term condylar surface smoothness.

Dopamine-Supported Metallization of Polyolefins─A Contribution to Transfer to an Eco-friendly and Efficient Technological Process.

Metallization is a common method to produce functional or decorative coatings on plastic surfaces. State-of-the-art technologies require energy-intensive process steps and the use of organic solvents or hazardous substances to achieve sufficient adhesion between the polymer and the metal layer. The present study introduces a facile bio-inspired "green" approach to improve this technology: the use of dopamine, a small-molecule mimic of the main structural component of adhesive mussel proteins, as an adhesion promoter. To understand dopamine adhesion and identify conditions for successful metallization, polyethylene surfaces were dip-coated with dopamine and metallized with nickel by electroless metallization; essential parameters such as temperature, pH value, concentration of dopamine and buffer, and the deposition time were systematically varied. Effects of adding oxidants to the dopamine bath, cross-linking, thermal and UV post-treatment of the polydopamine film, and plasma pretreatment of the substrate were investigated. The properties of the polydopamine layer and the quality of the metal film were studied by physico-chemical, optical, and mechanical techniques. It was shown that simple dip-coating of the substrate with dopamine under optimal conditions is sufficient to support metal layers with a good optical quality. Technologically relevant metal layer quality and adhesion were obtained with annealed and UV-treated polydopamine films and enhanced by plasma pretreatment of the substrate. The study shows that dopamine provides a new interfacial design for plastic metallization that can reduce energy consumption, use of hazardous substances, and reject rate during manufacturing. The results are essential findings for further technological developments of a universal platform to promote adhesion between plastics and metal or potentially also other material classes, enabling economic material development and more eco-friendly applications.

Obtainment and Characterization of Metal-Coated Polyethylene Granules as a Basis for the Development of Heat Storage Systems.

The research studied the feasibility of using copper-coated polyethylene granules as a basis for creating efficient heat storage systems. A technology for imparting catalytic properties to a polymer surface by the joint processing of polymer granules and an activator metal in a ball mill with their subsequent metallization in a chemical reducing solution is proposed. The efficiency of copper-coating a polyethylene surface is shown to be largely determined by the activation stage and the assumption regarding the mechanism of interaction of the activator metal with the polymer surface is made. To obtain different amounts of metal on the polyethylene granules, it is proposed that the method of remetallization is used. It was established that the rate of copper ion reduction depends on the number of previous coatings and is determined by the area of interaction of the metal-coated granules with the chemical reducing solution. The obtained metal-coated polyethylene granules were characterized in terms of the viability of using it as a phase transition material for a heat storage system. Using the developed installation that simulates the heat accumulator operation, it was shown that the efficiency of using metal-coated polyethylene granules to create heat storage systems is higher. The copper coating deposited on the polyethylene granules was studied using scanning electron microscopy and X-ray diffraction analysis.

Mechanical characteristics of the carbonized layer on the surface of polyethylene treated by the ion-plasma method

Polymer materials, in particular polyethylene, are actively used as a material for implants. Ion-plasma treatment improves the biocompatibility of polymers. This effect is achieved due to the formation of a carbonized layer on the polymer surface after ion-plasma treatment. This article examines the mechanical properties of the carbonized layer. In experiments on uniaxial tension, the dependence of the elastic modulus of the carbonized layer on the fluence of ion-plasma treatment was obtained. The dependence of the deformation corresponding to the destruction of the carbonized layer on the fluence of ion-plasma treatment was also determined. It was found that at high fluence values, the carbonized layer acquires properties corresponding to brittle materials, and at low ion doses, the properties of the polymer substrate material manifest themselves.

Screening of cultivation media for LDPE biodegradation by Penicillium verrucosum CNM-FP-02

The paper’s aim was to select the optimal mineral medium for LDPE biodegradation by the strain Penicillium verrucosum CNM-FP-02. It was selected 5 mineral salt media (MSM), which differed in salt content and N/P ratio. After 40 days of submerged cultivation, the following parameters were determined: catalase activity and pH of cultural media, biomass accumulation, rate of LDPE degradation, optical microscopy and the tensile testing of polyethylene. It was observed that catalase activity on all media, except MSM 4, was higher in the presence of LDPE. The addition of polyethylene to the growth media stimulated the fungal biomass accumulation by 19.3-93.1% (4 media out of 5 tested). The percentage of degradation of LDPE films was different, depending on the culture medium, from 0.41% to 0.92%. The most active LDPE films were degraded on medium MSM 2. Visualization of plastic strips under an optical microscope revealed the immobilization of the microorganism and the damage on the polyethylene surface. The tensile test showed increased elasticity of the plastic in the variants treated with fungal strain. In conclusion, in order to stimulate the biodegradation of LDPE by the strain P. verrucosum CNM-FP-02, the medium MSM 2 (N/P ratio 1:1) was selected.

Preventing Pseudomonas aeruginosa Biofilms on Indwelling Catheters by Surface-Bound Enzymes.

Implanted medical devices such as central venous catheters are highly susceptible to microbial colonization and biofilm formation and are a major risk factor for nosocomial infections. The opportunistic pathogen Pseudomonas aeruginosa uses exopolysaccharides, such as Psl, for both initial surface attachment and biofilm formation. We have previously shown that chemically immobilizing the Psl-specific glycoside hydrolase, PslGh, to a material surface can inhibit P. aeruginosa biofilm formation. Herein, we show that PslGh can be uniformly immobilized on the lumen surface of medical-grade, commercial polyethylene, polyurethane, and polydimethylsiloxane (silicone) catheter tubing. We confirmed that the surface-bound PslGh was uniformly distributed along the catheter length and remained active even after storage for 30 days at 4 °C. P. aeruginosa colonization and biofilm formation under dynamic flow culture conditions in vitro showed a 3-log reduction in the number of bacteria during the first 11 days, and a 2-log reduction by day 14 for PslGh-modified PE-100 catheters, compared to untreated catheter controls. In an in vivo rat infection model, PslGh-modified PE-100 catheters showed a ∼1.5-log reduction in the colonization of the clinical P. aeruginosa ATCC 27853 strain after 24 h. These results demonstrate the robust ability of surface-bound glycoside hydrolase enzymes to inhibit biofilm formation and their potential to reduce rates of device-associated infections.

Biofilm Formation of Clinical Klebsiella pneumoniae Strains Isolated from Tracheostomy Tubes and Their Association with Antimicrobial Resistance, Virulence and Genetic Diversity.

(1) Background: Due to the commonness of tracheotomy procedures and the wide use of biomaterials in the form of tracheostomy tubes (TTs), the problem of biomaterial-associated infections (BAIs) is growing. Bacterial colonization of TTs results in the development of biofilms on the surface of biomaterials, which may contribute to the development of invasive infections in tracheostomized patients. (2) Methods: Clinical strains of K. pneumoniae, isolated from TTs, were characterized according to their ability to form biofilms, as well as their resistance to antibiotics, whether they harbored ESβL genes, the presence of selected virulence factors and genetic diversity. (3) Results: From 53 patients, K. pneumoniae were detected in 18 of the TTs examined, which constituted 34% of all analyzed biomaterials. Three of the strains (11%) were ESβL producers and all had genes encoding CTX-M-1, SHV and TEM enzymes. 44.4% of isolates were biofilm formers, SEM demonstrating that K. pneumoniae formed differential biofilms on the surface of polyethylene (PE) and polyvinyl chloride (PVC) TTs in vitro. A large range of variation in the share of fimbrial genes was observed. PFGE revealed sixteen genetically distinct profiles. (4) Conclusions: Proven susceptibility of TT biomaterials to colonization by K. pneumoniae means that the attention of research groups should be focused on achieving a better understanding of the bacterial pathogens that form biofilms on the surfaces of TTs. In addition, research efforts should be directed at the development of new biomaterials or the modification of existing materials, in order to prevent bacterial adhesion to their surfaces.

Adhesion of water-based paint on plasma-treated high-density polyethylene sheets

In this study, high-density polyethylene (HDPE) surfaces were treated with plasma to enhance the adhesion of a water-based paint. A custom-built cold atmospheric pressure plasma jet (CAPPJ) device using a neon transformer as its power source was developed and used in the surface treatment. The jet nozzle of the device was made from polytetrafluoroethylene with two bare stainless-steel electrodes positioned laterally through the nozzle and opposite each other with a 1 mm gap. Gas was allowed to pass through the nozzle, exiting through a 1 mm diameter hole where a plasma jet is ejected through the arc from the electrodes. The effect of plasma treatment on HDPE surfaces was determined. Air and nitrogen were used as the process gases and exposure times were also varied. Hydrophilicity of the surface increased with longer plasma exposure with a corresponding 50% increase in surface free energy compared to the untreated surface. From Fourier transform infrared and x-ray photoelectron spectroscopy analysis, it was seen that plasma treatment introduced oxygen containing functionalities onto the surface. Increase in adhesion of a water-based paint was observed for plasma-treated HDPE sheets.

Space Charge Accumulation in Linear Low-Density Polyethylene with Surface Fluorination of the Semiconductive Electrode

Several fluorinated polyethylene surface studies have proved that the fluorination reaction can effectively prevent charge from being injected into polyethylene. Therefore, this paper explores the influence of fluorinated electrode on space charge behavior in polyethylene. In this study, the space charge distribution inside polyethylene is measured by laser-PWP (Pressure Wave Propagation) method while altering electrode fluorination duration and fluorination temperature. The experimental results show that measured homocharge injection is increased in polyethylene to which a fluorinated semiconductive electrode is heat pressed. Attenuated Total Reflectance-Infrared (ATR-IR) spectroscopy and Scanning Electron Microscope (SEM) are also performed, revealing that the fluorinated layer of semiconductive electrode on the interface between polyethylene and electrode block impurities from entering polyethylene. The measured space charge distribution, being the planar average amount, also reveals impurity generation since heterocharge formation is observed. As such impurities are blocked, in the meantime the electrodes' homocharge injection remains un-affected, thereby the measured apparent charge is greatly increased.

A simple and highly reliable method to enhance the adhesion properties of polyethylene using Kapton-taping process

Although polyethylene (PE) is one of the most frequently used synthetic polymers in the plastics market, it is very difficult to imprint or bond PE with adhesives without pre-treatments based upon electrical, chemical and thermal processes. This is because a uniform adhesion property of PE cannot be expected without these processes. In this study, we suggest a simple, fast and cost-effective method to improve the adhesion properties of PE using a Kapton tape, which is a polyimide film generally used in flexible electronics. Specifically, by wrapping PE substrates applied with an adhesive using a Kapton tape and curing the sample using either a hot-press or a hot plate, the standard deviation of the shear strength decreased by 82.1% and 87.6%, respectively. To further improve the adhesion of PE substrates, we functionalized their surface using coupling agents, such as (3-glycidoxypropyl) methyldiethoxysilane and (3-aminopropyl) trimethoxysilane after an ultraviolet-ozone process. Using X-ray photoelectron spectroscopy and vacuum Fourier-transform infrared spectroscopy analysis, we proved that a significant improvement in the adhesion of PE occurred because of chemical crosslinking between either epoxy or amine groups functionalized on the PE substrates and epoxy-based adhesives comprising diglycidyl ether epoxy resin and triethylenetetramine hardener. This study is important, as it suggests a simple and very effective method to obtain highly reliable adhesion properties of PE using conventional adhesives. Kapton-taping can be a simple, yet very effective, method to achieve highly reliable adhesion properties of polyethylene substrates with conventional adhesives, resulting in a significant decrease in the standard deviation of shear strength, in comparison to other curing methods, such as hot plate and hot-press. • We demonstrated a method to improve the adhesion properties of polyethylene by simply wrapping samples using a Kapton tape. • Kapton taping method significantly lowered the standard deviation of the shear strength. • Functional groups that can be crosslinked with the main components of the adhesive greatly improved the adhesive properties. • The ultraviolet-ozone treatment was necessary for facile modification of coupling agents on bare PE surface.

Developing eco‐friendly ceramic composite separator with competitive electrochemical properties using water‐based polymer binder for lithium‐ion batteries

The ceramic composite separators used in lithium-ion batteries (LIBs) are conventionally fabricated using a polymeric binder dissolved in an organic solvent, which can have adverse effects on the environment as well as the human body. Additionally, there are limited processes available for the fabrication of these separators owing to the requirement for carbon neutrality, which has attracted considerable attention worldwide to mitigate climate change. To address these issues, we propose an eco-friendly ceramic composite separator with outstanding adhesive strength and low interfacial resistance between the polyethylene (PE) separator and the aqueous polymeric binder with ceramic particles. To fabricate the proposed separator, the hydrophobic surface of the PE separator is preferentially modified into the hydrophilic surface by benzoyl peroxide (BPO) treatment. Following this, the water-soluble binder, that is, polyacrylic acid (PAA), with Al2O3 ceramic particles is coated on the surface of the pre-treated PE separator. The resultant PE separator with the hydrophilic surface and the water-based polymeric coating layer strongly adhere because of the formation of hydrogen bonds between the PAA and functional groups on the BPO pre-treated PE surface; these results in superior adhesive strength, and it reduces the interfacial resistance related with lithium-ion mobility through the separator. Consequently, the LIB half-cell employing the proposed separator displays superior rate performance and outstanding capacity retention.

The effect of electrospun polylactic acid/chitosan nanofibers on the low density polyethylene/ploy lactic acid film as bilayer antibacterial active packaging films

Bilayer antibacterial films were prepared using electrospun polylactic acid (PLA)/chitosan (Ch) nanofiber on low-density polyethylene (LDPE)/PLA films. Blends of Ch and PLA with the selected ratios of 5.0%, 10.0%, 15.0%, and 20.0% Ch were electrospun on the surface of LDPE/PLA composite film. Scanning electron microscopic images indicated a smooth and bead-free surface for all composite nanofibers with a diameter range from 50–200 nm. Fourier transform infrared spectra depict the presence of PLA and CH in the nanofiber. Hydrophobicity analysis showed that the PLA/Ch layer increase the hydrophobicity of bilayer films. The water vapor permeabilities of bilayer films were lower than those of LDPE/PLA film. The presence of PLA/Ch nanofiber layer resulted in the reduction in the oxygen permeability of bilayer films. When Ch content reached 10.0%, the bilayer films showed antibacterial activities against Escherichia coli and Staphylococcus aureus. Novelty impact statement Blends of chitosan and polylactic acid (PLA) was electrospun on to the surface of a low-density polyethylene (LDPE)/PLA film to produce bilayer antibacterial films. Electrospun nanofiber layers improved the antibacterial properties of the films and also reduced the oxygen and water vapor permeability levels of LDPE/PLA composite films without major interferences with their intrinsic physical and barrier properties.

Assessment of a Weak Mode of Bacterial Adhesion by Applying an Electric Field

Microbial attachment to surfaces is ubiquitous in nature. Most species of bacteria attach and adhere to surfaces via special appendages such as pili and fimbriae, the roles of which have been extensively studied. Here, we report an experiment on pilus-less mutants of Caulobacter crescentus weakly attached to polyethylene surface. We find that some individual cells transiently but repeatedly adhere to the surface in a stick-slip fashion in the presence of an electric field parallel to the surface. These bacteria move significantly slower than the unattached ones in the same field of view undergoing electrophoretic motion. We refer this behavior of repeated and transient attachment as “quasi-attachment”. The speed of the quasi-attached bacteria exhibits large variation, frequently dropping close to zero for short intervals of time. We propose a polymeric tethering model to account for the experimental findings. This study sheds light on bacteria–surface interaction, which is significant in broader contexts such as infection and environmental control.

Electron beam irradiation inactivation of Bacillus atrophaeus on the PET bottle preform and HDPE bottle caps with different original colonies

In this study, electron beam (EB) irradiation was used for the inactivation of Bacillus atrophaeus on the surface of polythylene terephthalate (PET) bottle preform and high-density polyethylene (HDPE) bottle caps. The effects of EB irradiation doses (0,1,3,5,7,9 kGy) and original inoculated colony counts (101,102,103,104,105,106,107 CFU/sample) were evaluated on the residues of B. atrophaeus and the quality attributes of bottle caps and preform. A Weibull model for simulating the sterilization data was established by fitting the microorganism inactivation curves with a high coefficient (R2 > 0.93). The reductions of the microorganism lethal rate (log N/N0) up to 7.11log, 6.21log, 5.59log were shown on 38 mm bottle cap, 28 mm bottle cap and bottle preform with the original colony counts of 107 CFU/sample after the EB irradiation treatment at 9 kGy, respectively. The b* values of bottle preform and caps were slightly affected and the highest color change was observed for 28 mm bottle cap treated by 9 kGy EB irradiation, which resulted in a decrease of b* value from −39.86 ± 0.15 to −41.25 ± 0.42. Nevertheless, EB irradiation could be applied in the decontamination of PET bottle preform and HDPE bottle caps under reasonable doses.

Using environmental sampling to evaluate the effectiveness of decontamination methods to reduce detection of porcine epidemic diarrhea virus RNA on feed manufacturing surfaces.

Porcine epidemic diarrhea virus (PEDV) is a possible biological hazard in feed mills. If the virus enters a feed mill, it becomes widely distributed and is difficult to decontaminate from both feed contact and non-feed contact surfaces. The objective of this study was to evaluate a variety of liquid and dry decontamination treatments that could be used to reduce the amount of PEDV found on feed manufacturing surfaces. This experiment was designed as a 5 × 10 factorial with five different feed manufacturing surfaces and 10 decontamination treatments with three replicates of each combination. Surfaces included stainless steel, solid polyethylene, woven polypropylene tote bag, rubber, and sealed concrete coupons. One mL (1×105 TCID50/mL) of stock PEDV was applied to each surface and allowed to dry completely for 60 min. Next, for decontamination requiring surface application, the application was performed and allowed 15 min contact time. The quantity of PEDV RNA was determined using quantitative reverse transcription PCR. A decontamination treatment × surface interaction was observed (P < 0.0001), indicating the efficacy of treatment is dependent upon the surface in which it is applied. Within the cement surfaces, the sodium hypochlorite resulted in the greatest (P < 0.05) cycle threshold (Ct) value, followed by formaldehyde which had a greater (P < 0.05) Ct value compared to remaining treatments. Within polyethylene, rubber, and stainless steel surfaces, the formaldehyde treated surfaces had the greatest Ct values (P < 0.05), followed by the sodium hypochlorite treatment, with other treatments all having lower Ct values (P < 0.05). For the woven polyethylene surfaces, the formaldehyde and sodium hypochlorite treatments had greater Ct values compared to all other treatments (P < 0.05). Additional research is necessary to identify the role of decontamination treatment on PEDV infectivity and develop methods for decontamination of feed manufacturing facilities.

Unravelling the attributes of novel cyanobacteria Jacksonvillea sp. ISTCYN1 by draft genome sequencing

Filamentous cyanobacteria, Jacksonvillea sp. ISTCYN1 was isolated from agriculture field and cultured in BG-11 medium. This study, report the genome sequence of cyanobacteria Jacksonvillea thatto the best of our knowledgeis the firstgenome sequenceof thisgenus. The 5.7 MB draft genome sequence of this cyanobacterium contains 5134 protein-coding genes. The phylogenetic tree was constructed based on genome and Desertifilum sp. IPPAS B-1220 validated the closest relationship with Jacksonvillea sp. ISTCYN1. The growth of strain ISTCYN1 has been reported in the presence of different types of plastic when used as a sole carbon source. SEM analysis revealed biofilm formation by cyanobacterial strain ISTCYN1 on the surface of high and low-density polyethylene and polypropylene. In the presence of these plastics, EPS production has also been reported by this strain. Whole genome sequence analysis reveals the presence of many genes involved in biofilm formation. The presence of key enzymes responsible for plastic degradation laccase, esterase, lipase, thioesterase, and peroxidase have been predicted in the genome analysis. Genome analysis also provides insight into the genes involved in biotin biosynthetic pathways. Furthermore, the presence of many selenoproteins reveals the selenium acquisition by this cyanobacterium.

About the deterioration of polyethylene exposed to plasma discharges: A comparison between two models

The present work is devoted to the modelling of the deterioration process of polyethylene exposed to reactive plasma. In particular, we present the comparison between two different models. The first one, already presented in the literature, considers the H-abstractions due to the OH· and O· radicals, and some successive reactions, involving mainly other gaseous species. The second model, in addition to the first model reactions, is enriched by including the effects (both H-abstractions and chemisorptions) due to the collisions of a series of plasma ions with the surface. These collisions have been reproduced by ab initio molecular dynamics simulations. The performance of both models has been tested by implementing them in a code for simulation of surface chemical reactions induced by a plasma discharge. The related results are then compared with some experimental data.The first model is able to well reproduce the experimentally detected oxidation of the polyethylene surface exposed to plasma discharges. The second model, including also the decisive effects of the NO· radical on an already oxidized surface, is able to explain the presence of nitrogen on the sample surface.

Impedance Characteristics of Biofilms Formed on Graphene Films and Their Substrates

Biofilms are inhomogeneous film-like matters formed on materials by bacterial activities. They bring about many detrimental problems in various fields such as cooling pipes, kitchens, toilets, baths, marine structures, food industries, medical applications, hospitals etc., as well as beneficial purposes. Therefore, they should be controlled properly and the sensing is very important therefore. We have confirmed so far that graphene as one of representative 2D materials has high sensitivity to biofilm formation due to their pi electron clouds. The characteristics would lead to the application of biofilm sensors. In this experiment, we formed one layer, two layers and multi-layers graphenes were formed by a thermal CVD process on copper substrates and in some cases, they were moved to the surfaces of polyethylene and biofilms were formed on graphene films with those substrates. Then the impedance characteristics were measured and the relation between the impedance characteristics and biofilms formation/growth behaviors were investigated and discussed. As a result, we obtained the following results.1. In the case of graphene films on all substrates, the characteristic peaks of impedance were observed at some specific frequencies.2. The impedance peaks were different between copper substrates and PE ones.3. The impedance peaks were also different according to the numbers of graphene layers.4. The impedance peaks became more remarkable for non-freeze hydrated specimens.5. In the case of polymeric substrates, the impedance characteristics of biofilms showed different patters.We presume that the impedance peaks were obtained, since external polymeric substances (EPS) in biofilms would have absorbed electromagnetic waves. Therefore, the polymeric substrates could have affected the absorbance behaviors of electromagnetic waves differently. The application possibilities of the experimental results to biofilm sensors were finally discussed.

Assessment of polyethylene degradation by biosurfactant producing ligninolytic bacterium.

Accumulation of plastic waste has become an environmental threat and a global problem. In this research, polyethylene degrading ligninolytic bacteria were isolated from plastic waste polluted soil. Two bacterial isolates, namely PE2 and PE3 have been obtained from the soil samples. Polyethylene degrading ability of the isolates has been assessed individually in a synthetic media containing polyethylene as a carbon source. The results indicated that maximum weight reduction of polyethylene (6.68%) was found in PE3 inoculated media after thirty days of incubation. Fourier Transform Infrared Spectroscopic results showed the appearance of carbonyl peaks. 16S rRNA gene sequencing studies revealed that the potential isolate PE3 belongs to the genus Bacillus and it was named Bacillus sp. strain PE3. From the scanning electron microscopic results, it is inferred that Bacillus sp. strain PE3 could colonize on the polyethylene surface and form a biofilm. Besides, the viable Bacillus sp. strain PE3 on polyethylene surface was confirmed by fluorescence microscopic analysis. Alkanes and fatty acids were identified in the degraded products by gas chromatography-mass spectrometer analysis. From the results of native polyacrylamide gel electrophoresis, the activities of laccase and lignin peroxidase were noticed. Furthermore, extracellular production of biosurfactant has been observed in the Bacillus sp. strain PE3 inoculated mineral salt media and synthetic media with glucose and polyethylene as the carbon source respectively. The characterization studies of crude biosurfactant have confirmed that lipopeptide nature biosurfactant. The present study demonstrates that the ligninolytic enzymes laccase, lignin peroxidase, and lipopeptide type biosurfactant are produced by Bacillus sp. strain PE3 in the media with polyethylene as a carbon source.

Interactions of SARS-CoV-2 with inanimate surfaces in built and transportation environments

Understanding the interactions and transmission of pathogens with/via inanimate surfaces common in the built environment and public transport vehicles is critical to promoting sustainable and resilient urban development. Here, molecular dynamics (MD) simulations are used to study the adhesion of SARS-CoV-2 (the causative agent of COVID-19) to some of these surfaces at different temperatures (same for surfaces and ambiance) ranging from −23 to 60 °C. Surfaces simulated are aluminum, copper, copper oxide, polyethylene (PE), and silicon dioxide (SiO2). Steered MD (SMD) simulations are also used to investigate the transfer of the virus from PE and SiO2 when a contaminated surface is touched. The virus shows the lowest and highest adhesions to PE and SiO2, respectively (20 vs 534 eV). Influence of temperature is not found to be noticeable. Using simulated water molecules to represent moisture on the skin, SMD simulations show that water molecules can lift the virus from the PE surface but damage the virus when lifting it from the the SiO2 surface. The results suggest that the PE surface is a more favorable surface to transmit the virus than the other surfaces simulated in this study. The results are compared with those reported in a few experimental studies.