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Determination of titanium speciation in consumer plastics by Raman microspectroscopy
Get PDFThe main component of objects made of plastic is an organic polymer matrix, but plastics also contain a wide range of other chemicals, such as additives, processing aids and unintentionally added substances. At present, the scientific and regulatory communities face challenges due to the lack of access to basic information on their quantity and identity, which is crucial in relation to potential toxicity, management, recycling, environmental fate and resource uses. Moreover, an additional problem is that some additives, such as titanium oxide (TiO2), can be present in different crystallographic forms, which makes it necessary to characterise not only the total amount of titanium present, but also its polymorph. Titanium dioxide is widely used in plastics and is found in two different polymorphs: anatase and rutile. Here we highlight several advantages of Raman microspectroscopy over conventional Raman spectroscopy in the detection of TiO2 in plastics and synthetic textiles. A main advantage derives from a better signal-to-background ratio due to its small sampling volume. In this study, it was possible to detect the TiO2 form at concentrations as low as ∼ 450 mg kg−1. Furthermore, we demonstrate that the choice of the less used 405 nm laser for Raman spectroscopy could overcome the unwanted fluorescence background in some cases. We found the presence of anatase in all textiles analysed and rutile in virtually all consumer plastic samples
A systematic review of biomonitoring microplastics in environmental matrices: Emphasis on airborne particles, dry deposits, and comparative analysis with traditional methods
Get PDFThe use of plastics continues to rise each year due to their versatility and essential role in industries like manufacturing, agriculture, and food packaging. However, plastics present a serious environmental challenge because they take over 500 years to decompose. During this time, they break down into tiny particles known as microplastics (MPs), which are now found everywhere, water, soil, and even the air we breathe. Recently, researchers have even detected MPs in clouds, making their presence in the atmosphere a growing concern for both the environment and public health. Traditional methods for sampling MPs in the air, such as active and passive techniques, can be expensive and complicated, often requiring specialized equipment and expertise. This has sparked interest in biomonitoring—an eco-friendly alternative that uses plants, mosses, and lichens to naturally trap MPs from the air. Biomonitoring offers a simpler, more cost-effective, and non-invasive way to study airborne MPs, providing a potential solution for long-term monitoring of air quality. In this review, we examine studies that have explored the use of plants to monitor atmospheric MPs and compare these methods with traditional sampling techniques. We highlight the advantages and limitations of both approaches, focusing on how biomonitoring can offer important insights into the types, concentrations, and distribution of MPs in the air. Additionally, biomonitoring helps us understand how these pollutants might be impacting living organisms. With MP pollution becoming an increasingly urgent issue, this review underscores the value of biomonitoring as a practical and sustainable tool for policymakers and environmental managers looking to address the growing problem of atmospheric MPs
The density of virgin, consumer and environmental plastics: An investigation using gas displacement pycnometry
Get PDFDensity is a fundamental property of plastics and is particularly significant in determining the transport and fate of waste plastics that enter aquatic systems. However, densities are rarely determined in the environmental literature and values employed for modelling or impacts are often unsourced or derived from secondary databases. In this study, we employ helium displacement pycnometry to determine the skeletal densities of non-porous plastics whose polymer composition had been established from manufacturer\u27s data, resin codes or Fourier transform infrared spectrometry. Two independent, collaborative laboratories, providing measurements within 3.5 % of each other and with precisions of \u3c1 % (as relative standard deviation), analysed a total of 42 virgin, consumer and environmental plastics consisting of ten common polymer types. Measured densities of plastics in all categories, and most notably for polybutylene terephthalate, polyethylene terephthalate, polypropylene and polyvinyl chloride, were often outside the ranges reported by a comprehensive online resource. Possible reasons for discrepancies include the occurrence of dense additives (evaluated by X-ray fluorescence analysis), the presence of inaccessible microscopic pores below a laminated surface, contamination of the main polymer by a secondary one, and structural changes on weathering. Regardless of precise causes, most results suggest that individual polymers have a broader range of densities than is generally published or considered in the literature. Accordingly, and in particular where buoyancy is critical, more precise, sample-specific measurements are recommended
Adverse fetal and perinatal outcomes associated with Zika virus infection during pregnancy: an individual participant data meta-analysis
Get PDFBackground: Zika virus (ZIKV) infection during pregnancy is associated with an increased risk of congenital malformations. The prevalence of short and long-term consequences, however, remains uncertain due to heterogeneity across studies. Individual Participant Data Meta-Analysis (IPD-MA) offers an alternative approach to provide more precise and generalisable estimates through data harmonisation across studies, allowing for standardised definitions and exploration of heterogeneity. This project was undertaken to estimate absolute and relative risks of adverse outcomes for individuals with ZIKV infection during pregnancy. Methods: IPD-MA studies and their datasets were identified through a systematic search conducted in 2018 with the following criteria: observational longitudinal or surveillance-based studies investigating ZIKV during pregnancy or at birth, measured fetal, infant, or child outcomes, and included at least 10 participants. Here we used IPD data shared by March 2022 from 18 studies from international health organisations and research networks, comprising 24 unique datasets, in 11 countries. Datasets were harmonised with standardised definitions, using variables related to pregnant individuals, methods used for ZIKV diagnoses, fetal characteristics and outcomes, and pooled for analysis. Frequentist and Bayesian regression methods were applied to estimate outcome prevalence and evaluate the association between maternal ZIKV infection and fetal loss, microcephaly and congenital zika syndrome as primary outcomes. Findings: Data including 9568 pregnant individuals and 9608 newborns, were harmonised. The risk of severe primary microcephaly was significantly higher in ZIKV-positive pregnancies (1.5%, CI 0.8%–2.7%) compared to ZIKV-negative ones (0.3%, CI 0.1%–1.0%), with a relative risk of 4.5 (CI 1.5–13.3) in the one-stage meta-analysis. While some risk estimates were consistent between Bayesian and Frequentist methods, estimates for other outcomes varied, underscoring the influence of both the analytical approach and the definition of ZIKV on the associations. Interpretation: Our findings align with previously published meta-analyses and indicate an added burden to adverse pregnancy outcomes with higher prevalence compared to pre-epidemic population-based average values. Future research should focus on additional outcomes with clear definitions of maternal infection. Women of reproductive age should be informed about the risks of Zika infection during pregnancy to support reproductive planning. Funding: This project was supported by the Wellcome Trust grant number 206532/Z/17/Z, the WHO Health Emergencies Programme Global Arbovirus Initiative, and the WHO Department of Sexual and Reproductive Health and Research, including the Human Reproduction Special Programme (HRP)
Metabolic Diversity of a Widely Distributed Tropical Freshwater Crab Is Not Underpinned by Genetic Differences
Get PDFAimThe aim of this study was to understand the interplay between local and regional factors as drivers of population physiological diversity in a tropical freshwater crab species.LocationWestern Ghats, south-west India.TaxonBarytelphusa cunicularis, Brachyura, Crustacea.MethodsWe applied an integrative approach combining population genetics and whole animal physiology, using the tropical freshwater crab Barytelphusa cunicularis as our model species. We tested for effects of population location (e.g., latitude, altitude), season (as a proxy for rainfall and water temperature) and/or warming on indices of whole animal respiratory physiology (metabolic rate, MO2) and hypoxic performance (Pcrit, i.e., the PO2 at which routine MO2 can no longer be sustained) in five widely distributed populations of this species. We also generated population genetic data (mtDNA COI and nDNA histone H3 sequences) to determine the extent of any population genetic structuring and/or cryptic species diversity present to verify that we were investigating a single species.ResultsDespite a high level of genetic structuring between the different populations of B. cunicularis examined, the genetic distances observed were consistent with intra- and not interspecific differences in freshwater crabs. Populations varied in the diversity of the physiological (MO2) responses observed. There were significant effects of season and population on respiration in response to temperature and Pcrit in response to acute hypoxia.Main ConclusionsWe conclude that local environmental factors are important in shaping physiological diversity between populations in tropical freshwater species and systems. This highlights the need to include population-level responses in any projections we make on how biodiversity will respond to ongoing and future environmental changes, including those caused by climate change
Characteristics, behaviour and fluxes of microplastics in the coastal boundary zones of the Persian Gulf and Oman Sea
No full textRelatively little is known about microplastics (MPs) in the atmosphere of the coastal zone, including their interaction with the sea surface. In this study, MPs have been determined and characterised in the lower atmosphere, advecting air, depositing dusts, coastal sediments and seawater of the Persian Gulf and Oman Sea using a variety of sampling techniques (including filtration of water and pumped air and deployment of a vertical array of sediment traps). MPs were detected in all samples and were dominated by fibres that were, in most cases, small (\u3c100 μm) and black. MP numbers captured in advecting air showed no trends with height or differences between locations or deployments over land and sea, but a clear increase was observed during strong winds. MPs in atmospheric suspension and in deposited dusts, sediments and seawater were also heterogeneously distributed. Environmental or transport pathway fractionation was evident according to morphology and particle size (% fibres and % small fibres) and to polymer density. Regarding the latter, relatively low-density polymers (e.g., polyethylene, polypropylene) were more abundant in the atmosphere, advecting air and seawater, whereas higher density polymers (e.g., regenerated cellulosics, polyethylene terephthalate) were more abundant in settling dusts and sediments. Fluxes, based on particle counts and converted MP m−2 h−1, revealed advection (up to ∼ 1.2 × 106) was greater than deposition (up to ∼ 400) by at least three orders of magnitude over land but only by a factor of a few hundred over sea. Neglecting any differences in resuspension, this suggests a greater net loss of airborne MPs over the ocean. Net settling velocities for the population of MPs in the lower atmosphere, derived from depositional fluxes and concentrations in air, ranged from about 1.2 to 13.1 m h−1, with residence times at an elevation of 10 m ranging from 45 min to 8.3 h. Our observations suggest that long-range transport of the type of MPs detected is constrained by a succession of deposition-resuspension cycles that must be factored into future modelling
Insights into marine biological responses to Icelandic glacial outburst floods from remote sensing data
Get PDFCryospheric change has altered discharge patterns of the subglacial Skaftá cauldrons and Grímsvötn volcano beneath the Vatnajökull ice cap, SE Iceland (64.4220° N, 16.7902° W) at least since 1940. Jökulhlaup (glacial outburst floods) frequency has increased but their magnitude has decreased. This study examines jökulhlaup effects on the marine environment at the Gígjukvísl, Skaftá, and Kúðafljót estuaries. Remote sensing data integrated in situ, observational, and modelled data to analyse sea surface salinity (1/8° resolution), temperature (0.05° resolution), and observational chlorophyll-a data (1 km² resolution). Covering 11 jökulhlaups in Gígjukvísl/Skaftá and seven in Kúðafljót, a systematic response emerged in residual data. Salinity reduced by 0.428 ± 0.444 (Gígjukvísl/Skaftá) and 0.280 ± 0.423 (Kúðafljót) on jökulhlaup start-days, with smaller declines one to two weeks later linked to seawater dilution. Temperatures fell by around -0.5 °C pre-flood at both sites (± 0.710 °C at Gígjukvísl/Skaftá and ± 0.658 at Kúðafljót) and up to -0.6 ± 0.209 °C (Kúðafljót) post-flood from ice dam melting and meltwater discharge. This aligns with partially significant chlorophyll-a pre-flood reductions of ~1.2 ± 0.496 mg/m3 and three post-flood peaks with mean increases by up to 1.446 ± 7.968 mg/m3 (Gígjukvísl/Skaftá) and 3.269 ± 11.810 mg/m3 (Kúðafljót), suggesting short algal blooms through increased nutrients and sediments. These results advance the understanding of anomalous glacial freshwater discharges, potentially affecting regional to global ocean circulation and productivity
The Economic Impact and Policy Implications of Innovative Medical Technologies on the Canadian Healthcare System
No full textAbstract - Hamid Sadri - The Economic Impact and Policy Implications of Innovative Medical Technologies on the Canadian Healthcare SystemDespite considerable per capita expenditure, the Canadian healthcare system faces a complex crisis characterised by strained operational capacity, substantial shortages of Health Human Resources (HHR), and suboptimal patient outcomes. This crisis arises from a decentralised and fragmented structure, further aggravated by isolated budget allocations and persistent underfunding of critical infrastructure and medical technologies. The outcomes of these issues include excessively prolonged wait times for essential procedures and diagnostics, limited access to primary and specialised care, and persistent health disparities that disproportionately affect residents of smaller provinces and rural areas. This doctoral dissertation addresses these urgent issues by investigating the manner in which the strategic incorporation of medical technologies may serve as an effective short- to medium-term solution. This approach aims to enhance system efficiency, improve patient health outcomes, and promote health equity across Canada. Grounded in the theoretical frameworks of economic evaluation and health policy, this research centres on three interrelated fundamental questions.• What are the implications of applying time-dependent activity-based costing (TDABC) and adopting a novel total cost of care framework that transcends traditional budgetary silos?• To what extent can the strategic implementation of medical technologies enhance access to healthcare and promote equity across the Canadian population?• How can a needs-stratification model for older adults be developed and implemented to improve the provision of long-term care (LTC) services in Canada?To attain these objectives, a series of integrated research initiatives and methodological analyses was systematically conducted. The methodologies encompassed (i) the application and validation of TDABC for precise cost measurement within the Canadian context, (ii) the evaluation of various innovative medical technologies through Budget Impact Analyses and Cost-Effectiveness Analyses. Specifically, the technologies assessed comprised implantable cardiac monitors for unexplained syncope, AI-assisted colonoscopy for colorectal cancer screening, and transcatheter aortic valve replacement for aortic stenosis. These evaluations were conducted from the perspectives of both a provincial healthcare payer and a hospital administrator to provide a comprehensive understanding of their financial implications and patient outcomes. Additionally, the scope of the research was expanded to include a critical review of the LTC sector, a need accentuated by the COVID-19 pandemic. This led to the development of a novel framework that integrates a needs-based screening and selection model for older adults and strategically incorporates technology to enhance the quality of care delivery. The findings of this dissertation challenge the conventional view that medical technologies are the primary drivers of escalating healthcare costs. Instead, the research offers empirical evidence suggesting that these technologies constitute strategic investments that yield long-term value for the healthcare system. The analyses demonstrate their economic viability by illustrating how they lead to improved outcomes and significant reductions in future healthcare resource utilisation, thereby compensating for initial capital expenditure. A key contribution is the effective employment of an integrated costing approach that transcends traditional budget silos, providing a more comprehensive and accurate depiction of the total cost of care. The dissertation introduces a novel strategy for the LTC sector, one that strategically exploits technology to enhance care efficiency and quality of life, primarily through the prioritisation of home-based LTC. By delivering robust, evidence-based solutions rooted in thorough economic analysis, this work offers policymakers practical guidance to address the most pressing challenges facing the Canadian healthcare system, guiding it toward a more sustainable and equitable future
Low-energy multiphoton scattering at tree-level and one-loop order in a homogeneous electromagnetic field
No full textWe study low energy photons coupled to scalar and spinor matter in the presence of an arbitrary homogeneous electromagnetic field in a first-quantized (worldline) approach. Utilizing a Fock-Schwinger gauge for both the scattering photons and homogeneous background, simple compact expressions are found for both the photon- and background-dressed effective action and propagator in scalar and spinor quantum electrodynamics. The low-energy limit allows identification of the coupling of the scattering photons as one of an effective homogeneous superposition of their field strengths, with amplitudes following from application of a suitable linearization operator. To treat the linearization, several techniques are employed, including a functional expansion based on the proper time formalism and worldline Green’s functions, linearized vertex operators under a worldline path integral, and a matrix expansion in the field strengths. We find, in particular, that a replacement rule converting scalar amplitudes to spinor amplitudes at one-loop order can, surprisingly, be extended to tree level amplitudes in the low energy limit. Finally, we discuss a novel worldline representation of the momentum space matter propagators, obtaining a suitable worldline Green’s function for this path integral satisfying homogeneous Dirichlet boundary conditions and momentum space vertex operators representing the scattering photons already in momentum space