Publications by authors named "Shaver M"

A diversity of chemicals are intentionally added to plastics to enhance their properties and aid in manufacture. Yet, the accumulated chemical composition of these materials is essentially unknown even to those within the supply chain, let alone to consumers or recyclers. Recent legislated and voluntary commitments to increase recycled content in plastic products highlight the practical challenges wrought by these chemical mixtures, amid growing public concern about the impacts of plastic-associated chemicals on environmental and human health.

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Article Synopsis
  • * Research focuses on high-density polyethylene (HDPE) and reveals that initial degradation mainly involves chain scission, which shifts to long-chain branching with increased exposure to oxygen.
  • * The study presents a rheology simulation method that can assess the quality of post-consumer recyclate (PCR), helping to improve recycling processes and support a circular plastics economy.
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Metal-free catalysts have garnered considerable interest as an environmental and economical alternative to precious metal catalysts. Bis(triphenylphosphine)iminium chloride (PPNCl) has emerged as a prominent choice due to its air and thermal stability and broad reactivity, especially in applications where a bulky cation is needed. The high phosphorus content and synthetic effort required for catalyst synthesis increase environmental impact; the recyclability of PPNCl in catalytic processes remains largely unexplored.

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Objective: The objective was to describe the social, environmental, and cultural adaptations to an existing falls program and assess acceptability and preliminary effectiveness of the program in reducing fear, reducing falls, and improving function among individuals poststroke in Guyana.

Methods: A quasi-experimental pilot study with a pretest/posttest in-group design was developed through a collaboration of researchers in Guyana and the US. Participants took part in the falls prevention program for 8 weeks.

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Fiber reinforced polymer composites (FRPs) are valuable construction materials owing to their strength, durability, and design flexibility; however, conventional FRPs utilize petroleum-based polymer matrices with limited recyclability. Furthermore, fiber reinforcements are made from nonrenewable feedstocks, through expensive and energy intensive processes, making recovery and reuse advantageous. Thus, FRPs that use biobased and degradable or reprocessable matrices would enable a more sustainable product, as both components can be recovered and reused.

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Background: Hypertension-induced mechanical stress on vascular smooth muscle cells (VSMCs) is a known risk factor for vascular remodeling, including vascular calcification. Caveolin-1 (Cav-1), an integral structural component of plasma membrane invaginations, is a mechanosensitive protein that is required for the formation of calcifying extracellular vesicles (EVs). However, the role of mechanics in Cav-1-induced EV formation from VSMCs has not been reported.

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The societal importance of plastics contrasts with the carelessness with which they are disposed. Their superlative properties lead to economic and environmental efficiency, but the linearity of plastics puts the climate, human health, and global ecosystems at risk. Recycling is fundamental to transitioning this linear model into a more sustainable, circular economy.

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Article Synopsis
  • Fluorophores with luminescence that changes based on concentration are important for applications like stress-sensing and dyeing in plastics.
  • Researchers study how the polymer's structure and properties affect this luminescence enhancement known as aggregation-induced enhanced emission (AIEE).
  • By optimizing dye and polymer interactions, and managing crystallinity, they find ways to improve quantification methods while addressing challenges like cost and efficiency.
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As society moves towards a net-zero future, the need to adopt more sustainable polymers is well understood, and as well as plastics, less visible formulation polymers should also be included within this shift. As researchers, industries and consumers move towards more sustainable products there is a clear need to define what sustainability means in fast moving consumer goods and how it can be considered at the design stage. In this perspective key challenges in achieving sustainable formulation polymers are highlighted, and opportunities to overcome them are presented.

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Polymeric frustrated Lewis pairs, or poly(FLP)s, have served to bridge the gap between functional polymer science and main group catalysis, pairing the uniqueness of sterically frustrated Lewis acids and bases with a polymer scaffold to create self-healing gels and recyclable catalysts. However, their utilization in radical chemistry is unprecedented. In this paper, we disclose the synthesis of polymeric frustrated radical pairs, or poly(FRP)s, by in situ photoinduction of FLP moieties, where their Lewis acidic and basic centers are tuned to promote single electron transfer (SET).

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The recycling of multimaterials such as payment or access cards poses significant challenges. Building on previous experimental work demonstrating the feasibility of chemically recyclable payment cards made from glycol-modified poly(ethylene terephthalate) (PET-G), we use life cycle assessment and techno-economic analysis to investigate two chemical recycling scenarios and evaluate their potential environmental and economic benefits. Recovering all components from the depolymerized products (Scenario 1) achieves substantial environmental benefits across most categories, reducing global warming by up to 67% compared to only recovering major components (Scenario 2).

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Most of plastic packaging waste does not degrade over time, which can lead to harmful effects on aquatic life and humans, highlighting the need for packaging materials that are easily degradable. Poly(mandelic acid) (PMA) is a biodegradable polymer that has been proposed as an alternative to polystyrene for use in packaging. However, its potential to replace the existing packaging materials also depends, among other factors, on the environmental sustainability of its production.

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Chemically cross-linked polymers offer excellent temperature and solvent resistance, but their high dimensional stability precludes reprocessing. The renewed demand for sustainable and circular polymers from public, industry, and government stakeholders has increased research into recycling thermoplastics, but thermosets have often been overlooked. To address this need for more sustainable thermosets, we have developed a novel bis(1,3-dioxolan-4-one) monomer, derived from the naturally occurring l-(+)-tartaric acid.

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Cardiovascular disease is the leading cause of death in the world, and vascular calcification is the most significant predictor of cardiovascular events; however, there are currently no treatment or therapeutic options for vascular calcification. Calcification begins within specialized extracellular vesicles (EVs), which serve as nucleating foci by aggregating calcium and phosphate ions. This protocol describes methods for obtaining and assessing calcification in murine aortas and analyzing the associated extracted EVs.

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Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) show immature features, but these are improved by integration into 3D cardiac constructs. In addition, it has been demonstrated that physical manipulations such as electrical stimulation (ES) are highly effective in improving the maturation of human-engineered cardiac tissue (hECT) derived from hiPSC-CMs. Here, we continuously applied an ES in capacitive coupling configuration, which is below the pacing threshold, to millimeter-sized hECTs for 1-2 weeks.

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Flap endonuclease 1 (FEN1) is an essential enzyme that removes RNA primers and base lesions during DNA lagging strand maturation and long-patch base excision repair (BER). It plays a crucial role in maintaining genome stability and integrity. FEN1 is also implicated in RNA processing and biogenesis.

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The linearity of the plastics economy is wasteful and polluting. To encourage recycling and decrease diversion to landfill, new legislation within the EU and UK will tax single-use plastic products made with less than 30% recycled plastic. At present, quantitative determination of recycled content is elusive and existing methods are inconsistent.

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Poor waste management and unchecked consumption underpin our current paradigm of plastics use, which is demonstrably unsustainable in the long term. Nonetheless, the utility and versatility of plastics suggest that the notion of a plastic-free society is also unsustainable. Responses to this conundrum are increasing, and among these are research efforts focused on the development of more sustainable plastics.

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Insulating materials are ubiquitous in a built environment and play a critical role in reducing the energy consumed to maintain habitable indoor environments. Mineral wool insulation (MWI) products, including glass, stone, and slag variants, are the most widely used class of insulating materials in Europe and account for more than 50% of the total market by volume. MWI typically consists of two key components: a mesh of inorganic fibers that are several micrometers in diameter, and an organic thermosetting adhesive commonly referred to as the "binder.

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Frustrated Lewis pairs (FLPs) are now ubiquitous as metal-free catalysts in an array of different chemical transformations. In this paper we show that this reactivity can be transferred to a polymeric system, offering advantageous opportunities at the interface between catalysis and stimuli-responsive materials. Formation of cyclic carbonates from cyclic ethers using CO as a C feedstock continues to be dominated by metal-based systems.

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Incorporating additives within host single crystals is an effective strategy for producing composite materials with tunable mechanical, magnetic and optical properties. The type of guest materials that can be occluded can be limited, however, as incorporation is a complex process depending on many factors including binding of the additive to the crystal surface, the rate of crystal growth and the stability of the additives in the crystallisation solution. In particular, the size of occluded guests has been restricted to a few angstroms - as for single molecules - to a few hundred nanometers - as for polymer vesicles and particles.

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Experimental and clinical studies have conclusively demonstrated that lowering elevated low-density lipoprotein cholesterol levels results in fewer major adverse cardiac events. Over the past few decades, statins have become the mainstay of lipid-lowering therapy, contributing significantly to the reduction of lipids, and providing patients with a cost-effective approach. However, with growing evidence in support of combination therapies providing increased benefits to certain patient populations, such as those intolerant to statins, there is an urgent need to investigate the safety and efficacy of alternative lipid-lowering drugs.

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Oxidative stress can damage organs, tissues, and cells through reactive oxygen species (ROS) by oxidizing DNA, proteins, and lipids, thereby resulting in diseases. However, the underlying molecular mechanisms remain to be elucidated. In this study, employing scanning ion conductance microscopy (SICM), we explored the early responses of human embryonic kidney (HEK293H) cells to oxidative DNA damage induced by potassium chromate (KCrO).

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Sterically hindered Lewis acid and base centers are unable to form Lewis adducts, instead forming frustrated Lewis pairs (FLPs), where latent reactivity can be utilized for the activation of small molecules. Applying FLP chemistry into polymeric frameworks transforms this chemistry into responsive and functional materials. Here, we report a versatile synthesis strategy for the preparation of macromolecular FLPs and explore its potential with the ring-opening reactions of cyclic ethers.

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