Viricidal Activity of Thermoplastic Polyurethane Materials with Silver Nanoparticles.

The use of diverse Ag-based nanoparticulated forms has shown promising results in controlling viral propagation. In this study, a commercial nanomaterial consisting of ceramic-coated silver nanoparticles (AgNPs) was incorporated into thermoplastic polyurethane (TPU) plates using an industrial protocol, and the surface composition, ion-release dynamics and viricidal properties were studied. The surface characterization by FESEM-EDX revealed that the molar composition of the ceramic material was 5.5 P:3.3 Mg:Al and facilitated the identification of the embedded AgNPs (54.4 ± 24.9 nm). As determined by ICPMS, the release rates from the AgNP-TPU into aqueous solvents were 4 ppm/h for Ag and Al, and 28.4 ppm/h for Mg ions. Regarding the biological assays, the AgNP-TPU material did not induce significant cytotoxicity in the cell lines employed. Its viricidal activity was characterized, based on ISO 21702:2019, using the Spring viraemia of carp virus (SVCV), and then tested against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The results demonstrated that AgNP-TPU materials exhibited significant (75%) and direct antiviral activity against SVCV virions in a time- and temperature-dependent manner. Similar inhibition levels were found against SARS-CoV-2. These findings show the potential of AgNP-TPU-based materials as a supporting strategy to control viral spread.

Investigation of the In Vitro and In Vivo Biocompatibility of a Three-Dimensional Printed Thermoplastic Polyurethane/Polylactic Acid Blend for the Development of Tracheal Scaffolds.

Tissue-engineered polymeric implants are preferable because they do not cause a significant inflammatory reaction in the surrounding tissue. Three-dimensional (3D) technology can be used to fabricate a customised scaffold, which is critical for implantation. This study aimed to investigate the biocompatibility of a mixture of thermoplastic polyurethane (TPU) and polylactic acid (PLA) and the effects of their extract in cell cultures and in animal models as potential tracheal replacement materials. The morphology of the 3D-printed scaffolds was investigated using scanning electron microscopy (SEM), while the degradability, pH, and effects of the 3D-printed TPU/PLA scaffolds and their extracts were investigated in cell culture studies. In addition, subcutaneous implantation of 3D-printed scaffold was performed to evaluate the biocompatibility of the scaffold in a rat model at different time points. A histopathological examination was performed to investigate the local inflammatory response and angiogenesis. The in vitro results showed that the composite and its extract were not toxic. Similarly, the pH of the extracts did not inhibit cell proliferation and migration. The analysis of biocompatibility of the scaffolds from the in vivo results suggests that porous TPU/PLA scaffolds may facilitate cell adhesion, migration, and proliferation and promote angiogenesis in host cells. The current results suggest that with 3D printing technology, TPU and PLA could be used as materials to construct scaffolds with suitable properties and provide a solution to the challenges of tracheal transplantation.

Nanokaolin reinforced carboxylated nitrile butadiene rubber/polyurethane blend-based latex with enhanced tensile properties and chemical resistance

The demand for gloves (e.g., disposable gloves, medical gloves) is increasing due to the Coronavirus disease 2019 (COVID-19) pandemic. Stability in the supply chain in the glove industry is important, and thus strategies are used to solve the problem of the shortage of nitrile gloves. The blending of nitrile butadiene rubber (NBR) with polyurethane (PU) and the use of the nanocomposite concept is among the feasible approaches. The present study aims to investigate the effects of nanokaolin (NK) on the tensile and chemical properties of carboxylated nitrile butadiene rubber (NBR)/polyurethane (PU) latex blends. Three different loadings of NK (10, 20, and 30 parts per hundred rubber) were added to the NBR/PU (at a blending ratio of 85/15). The zeta potential showed that all the NBR compounds exhibit good colloidal stability. The incorporation of NK increased the crosslink density and tensile strength of the NBR/PU latex blends. The highest tensile strength was achieved when the NK loading was 20 phr. All the NBR blends and nanocomposites (NBR/PU-based) possess tensile properties that fulfill the requirements for glove application. The chemical resistance of NBR compounds was increased by the incorporation of NK due to the higher crosslink density and barrier properties contributed by the NK. © The Author(s) 2023.

Polyurethane foams from vegetable oil-based polyols: a review.

Polyurethane is a versatile material that can be converted into various forms according to applications. PU foams or PUFs are the most commonly used polyurethanes. These are materials of low density and low thermal conductivity that make them highly suitable for thermal insulating applications. Most of the synthesis of PUFs is still based on the petrochemical industry. There are issues associated with the oil industry, such as environmental pollution, sustainability, and market instability. More recently, we have experienced the COVID-19 pandemic which has destroyed the global supply chain of raw materials. Such sudden disruption of the supply chain affects the global economy. To eliminate the reliance on special ingredients, it is important to find and produce alternate and domestic raw materials. Vegetable oils are organic, cost-effective, and economically viable and present in abundant amounts. The oil consists of triglycerides. It can be functionalized to provide polyol for PU foam synthesis. Herein, we review the literature on factors influencing the properties of PUFs depending on polyols from vegetable oil as well as present a glimpse of the conversion of vegetable oils into polyols for PUF synthesis.

Feasibility of nasal bridge pressure injury prevention using a protective dressing and the Halyard Fluidshield® N95 mask in a COVID-positive environment.

The purpose of this study was to prevent nasal bridge pressure injury among fit-tested employees, secondary to long-term wear of the N95 mask during working hours. A prospective, single-blinded, experimental cohort design. Participants were enrolled using the convenience sampling methods and randomisation was utilised for group assignment. Eligibility was determined by a COVID Anxiety Scale score and non-COVID clinical assignment. Participants with a history of previous skin injury or related condition were excluded. The experimental group was assigned Mepilex Lite® and the control group used Band- Aid®. Formal skin evaluations were done by Nurse Specialists who are certified in wound and ostomy care by the Wound, Ostomy, Continence, Nursing Certification Board (WOCNCB®). Fit test logs were provided to participants to measure subjective user feedback regarding mask fit and level of comfort. The results of this feasibility trial are promising in supporting the use of a thin polyurethane foam dressing as a safe and effective dressing to apply beneath the N95 mask. Additional research is needed to validate results due to limited data on efficacy and safety of the various barrier dressings as a potential intervention to prevent skin breakdown to the nasal bridge.

USE OF POLYURETHANE INSULATED CHAMBERS TO REDUCE POST-HARVEST LOSSES OF FARM PRODUCE FOR THE NIGERIAN MARKET

General metabolic activity rises with increasing temperature in farm produce, which commonly leads to post-harvest losses. In recent times, control of temperature has been used successfully to control deterioration and maintain viability of these farm produce. This study focused majorly on post-harvest losses which are a recurring issue in Nigeria's agricultural sector, especially in the heat of COVID-19 pandemic. It also focused on the driving factors and the proactive measures that were adopted to tackle the problem. Losses of agricultural produce can occur before, during, or after harvesting. Post-harvest losses focus on the latter and are of great concern to the agricultural sector. Preservation of these produce can be achieved using a regulated and temperature-controlled storage area. Rigid polyurethane (PU), commonly used for insulated chambers, has a very low thermal conductivity coefficient of 0.023W/m.K at 10°C with an average K-value of 1.14m2 k/W per inch, depending on the formulation density. Rigid PU exhibits very good dimensional stability between -180 °C and +140 °C, making it a suitable storage technology to forestall and reduce post-harvest losses of agricultural produce. Nigeria has experienced an unimaginable food loss since the outbreak of the COVID-19 pandemic, threatening food security and precipitating massive importation. This has led to a surge in the country's post-harvest losses, currently estimated at $9billion (N3.4 trillion based on the current official exchange rate of N380) by the Federal Ministry of Agriculture. Post-harvest losses in Africa's most populous nation have been estimated to range between 5% and 20% for grains, 20% for fish and as high as between 50% and 60% for tubers, fruits and vegetables. Losses can be the result of reduction in quality and safety. In the absence of quality packaging and refrigeration systems for controlled temperature, farm produce deteriorate faster while the farmer waits to sell. Vitapur Nig. Ltd., a PU insulation company developed a PU-insulated chamber with a tricycle as its carrier to help forestall post-harvest losses. The designed regulated, PU-insulated chamber helps to preserve the quality of farm produce and the transportation problem is solved using the tricycle as the carrier. The study showed that the PU-insulated chamber, a composite that comprises majorly of rigid PU systems (Polyol and Isocyanate) and chromadek sheets as the facer can help reduce post-harvest losses by almost 27%, depending on the specific design used. [ FROM AUTHOR]

New In Situ-Generated Polymer-Iodine Complexes with Broad-Spectrum Antimicrobial Activity.

Iodine-containing systems show broad antiseptic properties that can be an invaluable tool in controlling infections in humans and animals. Here, we describe the first proof-of-concept studies on biocidal active polyamide- and polyurethane-iodine complexes that are produced in situ directly during the fabrication and/or polymerization process at laboratory and commercially relevant scales. These polymer-iodine materials are active against a broad range of microorganisms, including bacteria and fungi. It is suggested that the ease of manufacture and subsequent commercialization make said systems especially suited for applications as base materials for medical devices to reduce infection risks and control the spread of pathogens. IMPORTANCE Infectious diseases are of mounting medical and public concern. A major contributor to this trend is the proliferation of medical implants, which are inherently vulnerable to microbial contamination and the subsequent onset of hospital-acquired infections. Moreover, implant-associated infections in humans are often difficult to diagnose and treat and are associated with substantial health care costs. Here, we present the development of biocidal active polyamide- and polyurethane-iodine complexes that are generated in situ during fabrication. We show that the excellent antiseptic properties of water-soluble povidone-iodine can be similarly realized in water-insoluble engineering plastics, specifically polyamide- and polyurethane-iodine. These complexes have inherent biocidal activity against major pathogenic bacteria and fungi.

Synthesis and Evaluation of a Silver Nanoparticle/Polyurethane Composite That Exhibits Antiviral Activity against SARS-CoV-2.

In this proof-of-concept study, we aim to produce a polyurethane (PU)-based composite that can reduce the amount of viable SARS-CoV-2 virus in contact with the surface of the polymeric film without further interventions such as manual cleaning. Current protocols for maintaining the hygiene of commonly used touchpoints (door handles, light switches, shop counters) typically rely on repeated washing with antimicrobial products. Since the start of the SARS-CoV-2 pandemic, frequent and costly surface sanitization by workers has become standard procedure in many public areas. Therefore, materials that can be retrofitted to touchpoints, yet inhibit pathogen growth for extended time periods are an important target. Herein, we design and synthesise the PU using a one-pot synthetic procedure on a multigram scale from commercial starting materials. The PU forms a robust composite thin film when loaded with 10 wt% silver nanoparticles (AgNPs). The addition of AgNPs increases the ultimate tensile strength, modules of toughness and modulus of elasticity at the cost of a reduced elongation at break when compared to the pristine PU. Comparative biological testing was carried out by the addition of pseudotyped virus (PV) bearing the SARS-CoV-2 beta (B.1.351) VOC spike protein onto the film surfaces of either the pristine PU or the PU nanocomposite. After 24 h without further human intervention the nanocomposite reduced the amount of viable virus by 67% (p = 0.0012) compared to the pristine PU treated under the same conditions. The significance of this reduction in viable virus load caused by our nanocomposite is that PUs form the basis of many commercial paints and coatings. Therefore, we envisage that this work will provide the basis for further progress towards producing a retrofittable surface that can be applied to a wide variety of common touchpoints.

A hand-targeted auxiliary personal protective equipment for intervention of fomite transmission of viruses.

In COVID-19, fomite transmission has been shown to be a major route for the spreading of the SARS-CoV-2 virus due to its ability to remain on surfaces for extended durations. Although glove wearing can mitigate the risk of viral transmission especially on high touch points, it is not prevalent due to concerns on diversion of frontline medical resources, cross-contamination, social stigma, as well as discomfort and skin reactions derived from prolonged wearing. In this study, we developed FlexiPalm, a hand-targeted auxiliary personal protective equipment (PPE) against fomite transmission of viruses. FlexiPalm is a unique palmar-side hand protector designed to be skin-conforming and transparent, fabricated from medical-grade polyurethane transparent film material as a base substrate. It serves primarily as a barrier to microbial contamination like conventional gloves, but with augmented comfort and inconspicuousness to encourage a higher public adoption rate. Compared to conventional glove materials, FlexiPalm demonstrated enhanced mechanical durability and breathability, comparable hydrophobicity, and displayed a minimal adsorption of SARS-CoV-2 spike protein and virus-like particles (VLP). Importantly, FlexiPalm was found to bind significantly less viral protein and VLP than artificial human skin, confirming its ability to reduce viral contamination. A pilot study involving participants completing activities of daily living showed a high level of comfort and task completion, illustrating the usability and functionality of FlexiPalm. Moreover, we have demonstrated that surface modification of FlexiPalm with microtextures enables further reduction in viral adsorption, thereby enhancing its functionality. An effective implementation of FlexiPalm will bolster PPE sustainability and lead to a paradigm shift in the global management of COVID-19 and other infectious diseases in general.

Determining the effects of some bacteria on wooden toys treated with antibacterial protective coatings

Several protective coatings enhanced by antimicrobial agents and/or pigments were considered for the wooden toy market: water-based matte varnish, an ultra-hygiene water-based matte varnish (WBV-UH), a polyurethane matte varnish (PUV), and an ultra-hygiene antiviral polyurethane matte varnish (PUV-UH), as well as a water-based dye (WBV 5%K), an ultra-hygiene water-based dye (WBV-UH 5%K), a polyurethane dye (PUV 5%K), and an ultra-hygiene polyurethane dye (PUV-UH 5%K), which contain 5% red nano-pigment (K). By utilizing 7 kinds of bacteria and 2 types of yeast that are commonly detected in routine, daily settings, the efficacy of the different protective coatings on wooden toy surface was investigated. The antibacterial and antimicrobial activities of the tested dye samples were based on the agar-well diffusion method. Ultimately, the study found that the addition of antimicrobial agents to several different protective coatings and dyes resulted in the presence of antimicrobial activity vs. the lack thereof with protective coatings and dyes alone. Additionally, some of the dyes with added antimicrobial agents were found to be effective against biofilm formation. Overall, the addition of pigment into the coating, alongside the addition of antimicrobial agents, proved to be highly effective in inhibiting growth and spread of microorganisms on wooden toy surface.

Hydrogen-rich gas production from disposable COVID-19 mask by steam gasification.

Globally, the demand for masks has increased due to the COVID-19 pandemic, resulting in 490,201 tons of waste masks disposed of per month. Since masks are used in places with a high risk of virus infection, waste masks retain the risk of virus contamination. In this study, a 1 kg/h lab-scale (diameter: 0.114 m, height: 1 m) bubbling fluidized bed gasifier was used for steam gasification (temperature: 800 °C, steam/carbon (S/C) ratio: 1.5) of waste masks. The use of a downstream reactor with activated carbon (AC) for tar cracking and the enhancement of hydrogen production was examined. Steam gasification with AC produces syngas with H2, CO, CH4, and CO2 content of 38.89, 6.40, 21.69, and 7.34 vol%, respectively. The lower heating value of the product gas was 29.66 MJ/Nm3 and the cold gas efficiency was 74.55 %. This study showed that steam gasification can be used for the utilization of waste masks and the production of hydrogen-rich gas for further applications.

Aerogel-Functionalized Thermoplastic Polyurethane as Waterproof, Breathable Freestanding Films and Coatings for Passive Daytime Radiative Cooling.

Passive daytime radiative cooling (PDRC) is an emerging sustainable technology that can spontaneously radiate heat to outer space through an atmospheric transparency window to achieve self-cooling. PDRC has attracted considerable attention and shows great potential for personal thermal management (PTM). However, PDRC polymers are limited to polyethylene, polyvinylidene fluoride, and their derivatives. In this study, a series of polymer films based on thermoplastic polyurethane (TPU) and their composite films with silica aerogels (aerogel-functionalized TPU (AFTPU)) are prepared using a simple and scalable non-solvent-phase-separation strategy. The TPU and AFTPU films are freestanding, mechanically strong, show high solar reflection up to 94%, and emit strongly in the atmospheric transparency window, thereby achieving subambient cooling of 10.0 and 7.7 °C on a hot summer day for the TPU and AFTPU film (10 wt%), respectively. The AFTPU films can be used as waterproof and moisture permeable coatings for traditional textiles, such as cotton, polyester, and nylon, and the highest temperature drop of 17.6 °C is achieved with respect to pristine nylon fabric, in which both the cooling performance and waterproof properties are highly desirable for the PTM applications. This study opens up a promising route for designing common polymers for highly efficient PDRC.

Diseño de prótesis para amputación transmetatarsal y de Chopart

La Diabetes Mellitus es una enfermedad crónica no transmisible de origen multifactorial, cuya prevalencia en Chile es de 12,3% en la población mayor a 15 años. Dentro de las consecuencias de esta enfermedad se encuentra el pie diabético, cuyo tratamiento principal es la amputación parcial del pie. En este contexto, el objetivo de la investigación es diseñar una prótesis parcial de pie para los niveles de amputación transmetatarsal y de Chopart. La metodología empleada incluyó el establecimiento del perfil del paciente, la definición de las especificaciones de diseño y la posterior propuesta del diseño conceptual. Luego se abordó el diseño de detalle, realizando los cálculos de las fuerzas a las que está sometida la prótesis, la selección del material y el análisis de esfuerzos empleando el método de elementos finitos, para establecer el material y dimensiones definitivas. La prótesis diseñada está compuesta por una plantilla de material poliuretano-termoplástico o de polipropileno, y una cubierta estética de silicona;incluye en la misma plantilla los dos niveles de amputación parcial de pie, no restringe los grados de libertad del tobillo y es personalizada para el paciente, lo cual es relevante cuando se trabaja con pacientes con diabetes.Alternate :Diabetes Mellitus is a non-communicable chronic disease of multifactorial origin, whose prevalence in Chile is 12.3% in the population over 15 years of age. Among the consequences of this disease there is the diabetic foot, whose main treatment is the partial amputation of the foot. In this context, the objective of the research is to design a partial foot prosthesis for the transmetatarsal and Chopart levels of amputation. The used methodology included the establishment of the patient's profile, the definition of the design specifications and the subsequent proposal of the conceptual design. Then the detailed design was approached, carrying out the calculations of the forces to which the prosthesis is subjected, the material selection and the stress analysis using the finite element method to establish the final material and dimensions of the prosthesis. The designed prosthesis is composed of a polyurethane-thermoplastic or polypropylene material insole, and an aesthetic silicone cover;It includes both levels of partial foot amputation in the same template, does not restrict the degrees of freedom of the ankle, and is personalized for the patient, which is relevant when working with patients with diabetes.

Transparent Polyurethane Coating with Synergistically Enhanced Antibacterial Mechanism Composed of Low Surface Free Energy and Biocide

Recently, antibacterial coatings have gained great attention after the outbreak of COVID-19, thus durable transparent polyurethane (PU) coatings with anti-bacterial and anti-fingerprint performances are highly desired. In this work, the low surface free energy enables the hydroxyl-terminated polysiloxanes modified with quaternary ammonium salts (PQMS) enriched on the surface. The optimal PU-PQMS-40% coating with the thickness of 15 μm displayed 96% light transmittance and can be adopted to diverse substrates. This resultant coating exhibits excellent antibacterial activity against Gram-negative E. coli (99.2%) and Gram-positive S. aureus (98.6%) because of the synergistically enhanced antibacterial mechanism of both low surface free energy (27.54 ± 0.75 mJ·m−2) and quaternary ammonium salts (QAs). It is noteworthy that this antibacterial PU coating is capable of retaining its properties even after being subjected to 210 cycles of abrasion tests, manifesting a superior self-renewability. This coating system with combined features of transparency, antibacterial performance, chemical resistance, and durability make it a promising candidate for applications in the fields of electronic devices, automobile interiors, intelligent glass, and marine antifouling.

A Student-Led, Virtually-Developed Suborbital Payload: Investigating the Structure of Polyurethane Foam in Microgravity

The global COVID-19 pandemic impacted student science-led initiatives globally, forcing them to either cancel, postpone, or re-imagine their efforts in order to serve and inspire students. One such initiative, Shad Canada, a month-long summer STEAM and Entrepreneurship program for Canadian high school youth, that challenges its participants to create novel solutions to grand global and human challenges. In typical years, participants congregate physically in campuses to work in teams to devise solutions to societal problems. In the era of COVID-19, Shad went virtual. The program devised a novel challenge for their 2020 cohort: to design a microgravity payload for suborbital flight that leverages space and microgravity in a meaningful and creative way with impacts for science, research and humanity - all while collaborating online. Shad partnered with Luna Design and Innovation to create Canada’s first fully remote commercial space flight competition, offering one winning team 3-minutes of microgravity to test their research aboard Blue Origin’s New Shepard reusable suborbital vehicle. Working with industry, academic partners, Canadian Space Agency engineers, and other mentors and experts, sixty-two teams of over 600 students took on the challenge, proving their ability to adapt, innovate, and come together under one common goal. A judging panel of Shad representatives and industry experts evaluated the final projects based on their impact, scientific merit, technical feasibility and project plan. Mous4Inc. was ultimately selected as the winner of the Shad 2020 Design Challenge, developing a project that investigates the formation and structure of polyurethane foam in microgravity. This diverse team of ten students from across the country continue to work with mentors to develop a spaceborne polyurethane foam, with potential terrestrial applications. In the end, having strong communication, teamwork, and a central goal of connecting their ideas and interests was able to help Mous4Inc. design this winning project. This presentation centers around the student team’s experience with virtual suborbital payload development, believed to be the first student-led virtually-developed suborbital payload in Canada. This work will highlight both the novel virtual distributed payload development and building process, the value of such virtual payload development programs for other secondary students, lessons learned, and Mous4Inc.’s next steps with respect to launch, post-flight testing, publication and outreach. Copyright © 2021 by the International Astronautical Federation (IAF). All rights reserved.

State-of-the-art review of advanced electrospun nanofiber yarn-based textiles for biomedical applications.

The pandemic of the coronavirus disease 2019 (COVID-19) has made biotextiles, including face masks and protective clothing, quite familiar in our daily lives. Biotextiles are one broad category of textile products that are beyond our imagination. Currently, biotextiles have been routinely utilized in various biomedical fields, like daily protection, wound healing, tissue regeneration, drug delivery, and sensing, to improve the health and medical conditions of individuals. However, these biotextiles are commonly manufactured with fibers with diameters on the micrometer scale (> 10 µm). Recently, nanofibrous materials have aroused extensive attention in the fields of fiber science and textile engineering because the fibers with nanoscale diameters exhibited obviously superior performances, such as size and surface/interface effects as well as optical, electrical, mechanical, and biological properties, compared to microfibers. A combination of innovative electrospinning techniques and traditional textile-forming strategies opens a new window for the generation of nanofibrous biotextiles to renew and update traditional microfibrous biotextiles. In the last two decades, the conventional electrospinning device has been widely modified to generate nanofiber yarns (NYs) with the fiber diameters less than 1000 nm. The electrospun NYs can be further employed as the primary processing unit for manufacturing a new generation of nano-textiles using various textile-forming strategies. In this review, starting from the basic information of conventional electrospinning techniques, we summarize the innovative electrospinning strategies for NY fabrication and critically discuss their advantages and limitations. This review further covers the progress in the construction of electrospun NY-based nanotextiles and their recent applications in biomedical fields, mainly including surgical sutures, various scaffolds and implants for tissue engineering, smart wearable bioelectronics, and their current and potential applications in the COVID-19 pandemic. At the end, this review highlights and identifies the future needs and opportunities of electrospun NYs and NY-based nanotextiles for clinical use.

Microplastic Extraction from the Sediment Using Potassium Formate Water Solution (H2O/KCOOH)

Microplastics (MPs) are considered an important stratigraphic indicator, or ‘technofossils’, of the Anthropocene. Research on MP abundance in the environment has gained much attention but the lack of a standardized procedure has hindered the comparability of the results. The development of an effective and efficient method of MP extraction from the matrix is crucial for the proper identification and quantifying analysis of MPs in environmental samples. The procedures of density separation used currently have various limitations: high cost of reagents, limited solution density range, hazardous reagents, or a combination of the above. In this research, a procedure based on density separation with the use of potassium formate water solution (H2O/KCOOH) in controlled conditions was performed. Experimental sediment mixtures, spiked with polyethylene (PE), polystyrene (PS), polyurethane (PUR) and polyethylene terephthalate (PET) particles were prepared and an extraction procedure was tested in the context of a weight-based quantitative analysis of MPs. This article discusses the effectiveness and safety of the method. It additionally provides new information on the interactions between MP particles and the mineral matter of the sediment. Results were acquired with the use of instrumental methods, namely thermogravimetry (TG), Fourier Transform Infrared (FTIR) spectroscopy, Field Emission Scanning Electron microscopy and Energy Dispersive spectrometry (SEM/EDS), as well as X-ray fluorescence (XRF) analysis.

Catalytic upgrading of the polymeric constituents in Covid-19 masks

A substantial volume of various types of Covid-19 masks has been disposed of since the start of the global pandemic. These facemasks are made of non-degradable polymeric materials. As such, they currently signify a major source of microplastic pollution in the environment. Through incineration or pyrolysis, thermal processing has emerged as a mainstream approach in the waste management of the ever-increasing loads of generated facemasks. Via a combined experimental-theoretical framework, we report herein salient features that govern thermal decomposition of the distinct plastic-based components in 3 M N95 (with a respirator) and surgical facemasks. Protective three-four layers in the considered masks are composed of polypropylene (PP) that degrades in a one-step across the temperature window 330 - 480 degrees C. Char residues from the decomposition of ear straps (consisting of polyester) attain 24% and 15% fractions of the initial mass in the case of surgical and N95 masks, respectively. Thermo kinetic parameters are derived for the different components of the facemask by using the Coats-Redfern approach from the thermogravimetric analysis data. Here we also report the potentiality of producing value-added products from the face mask using the GCMS by virtue of the catalytic oxidation of the material expending the Niobium doped CeO2 catalyst under controlled conditions. Constructed mechanisms through density functional theory (DFT) computations illustrated the nature of chemical reactions that mark the two-stage decomposition curve of polyurethane (the material used in the nose area in N95 masks). These chemical events characterize rupture of C-C(O) bonds, sequential departure of CO2/C2H4 molecules, and fission of the C-C linkages. Outcomes from this investigation provide important information (i.e., thermal stability regions of the deployed polymers and potential emission profiles) needed in the urgent pursuit to safely and economically recycle polymeric constituents in Covid-19 masks, and potentially other types of medical wastes.

Autoclavable, Breathable, and Waterproof Membranes Tailored by Ternary Nanofibers for Reusable Medical Protective Applications

The COVID-19 created severe shortages of prevention materials and supplies, and the reuse of medical protective clothing is ongoing worldwide. However, it has remained a significant challenge to realize the reusability of the current medical protective clothing. We reported a scalable strategy to create autoclavable ternary electrospun nanofibrous membranes (TENMs) by introducing the elastomer polyurethane (PU) and low-surface-energy fluorinated polyurethane (FPU) into poly(ether sulfone) (PES) fibers via electrospinning. The advantage of this design was that we could balance the waterproof-breathable function and the thermostable performance of the membrane by controlling the PES/PU/FPU mass ratio. The resulting TENMs showed excellent performances of a high moisture transmission rate of 8.3 kg m-2 day-1, a high hydrostatic pressure of 82.56 kPa, a high bacteria retention rate of 99.99%, a high aerosol retention rate of 99.99%, and autoclave sterilization-invariant to 10 cycles. The successful preparation of the material can lead to the reuse of medical protective clothing in the foreseeable future. © 2021 American Chemical Society.

COVID 19 vaccine distribution solution to the last mile challenge: Experimental and simulation studies of ultra-low temperature refrigeration system.

Most COVID-19 vaccines require ambient temperature control for transportation and storage. Both Pfizer and Moderna vaccines are based on mRNA and lipid nanoparticles requiring low temperature storage. The Pfizer vaccine requires ultra-low temperature storage (between -80 °C and -60 °C), while the Moderna vaccine requires -30 °C storage. Pfizer has designed a reusable package for transportation and storage that can keep the vaccine at the target temperature for 10 days. However, the last stage of distribution is quite challenging, especially for rural or suburban areas, where local towns, pharmacy chains and hospitals may not have the infrastructure required to store the vaccine. Also, the need for a large amount of ultra-low temperature refrigeration equipment in a short time period creates tremendous pressure on the equipment suppliers. In addition, there is limited data available to address ancillary challenges of the distribution framework for both transportation and storage stages. As such, there is a need for a quick, effective, secure, and safe solution to mitigate the challenges faced by vaccine distribution logistics. The study proposes an effective, secure, and safe ultra-low temperature refrigeration solution to resolve the vaccine distribution last mile challenge. The approach is to utilize commercially available products, such as refrigeration container units, and retrofit them to meet the vaccine storage temperature requirement. Both experimental and simulation studies are conducted to evaluate the technical merits of this solution with the ability to control temperature at -30 °C or -70 °C as part of the last mile supply chain for vaccine candidates.