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1.
Sci Total Environ ; : 157419, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35850331

RESUMO

Although potentially hazardous chemical elements (e.g., Cu, Cr, Pb, Sb, Ti, Zn) have been studied in clothing textiles, their presence in cleaning textiles is unknown. In this study, 48 cleaning cloth products (consisting of 81 individual samples) purchased in Europe, and consisting of synthetic (petroleum-based), semi-synthetic or natural fibres or combinations of these different types, have been analysed for 16 chemical elements by X-ray fluorescence (XRF) spectrometry. Titanium was detected in most cases (median and maximum concentrations ~3700 and 12,400 mg kg-1, respectively) and Raman microspectroscopy revealed that TiO2 was present as anatase. Barium, Br, Cr, Cu, Fe and Zn were frequently detected over a range of concentrations, reflecting the presence of various additives, and Sb was present at concentrations up to about 200 mg kg-1 in samples containing polyester as catalytic residue from the polymerisation process. Lead was detected as a contaminant in four samples and at concentrations below 10 mg kg-1. Overall, the range of the chemical element profiles and concentrations was similar to those for clothing materials published in the literature, suggesting that broadly the same additives, materials and processes are employed to manufacture cloths and clothing textiles. The mechanisms by which potentially hazardous chemical elements are released into the environment with microfibres or mobilised into soluble or nano-particulate forms remain to be explored.

2.
J Phys Chem A ; 2022 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-35852300

RESUMO

The UV photolysis of solid FOX-7 at 5 K with 355 and 532 nm photons was investigated to unravel initial isomerization and decomposition pathways. Isomer-selective single photon ionization coupled with reflectron time-of-flight mass spectrometry (ReTOF-MS) documented the nitric oxide (NO) loss channel at 355 nm along with a nitro-to-nitrite isomerization, which was observed by using infrared spectroscopy, representing the initial reaction pathway followed by O─NO bond rupture of the nitrite moiety. A residual gas analyzer detected molecular oxygen for the 355 and 532 nm photolysis at a ratio of 4.3 ± 0.3:1, which signifies FOX-7 as an energetic material that provides its own oxidant once the decomposition starts. Overall branching ratios for molecular oxygen versus nitric oxide were derived to be 700 ± 100:1 at 355 nm. It is notable that this is the first time that molecular oxygen was detected as a decomposition product of FOX-7. Computations show that atomic oxygen, which later combines to form molecular oxygen, is likely released from a nitro group involving conical intersections. The condensed phase potential energy profile computed at the CCSD(T) and CASPT2 level correlates well with the experiments and highlights the critical roles of conical intersections, nonadiabatic dynamics, and the encapsulated environment that dictate the mechanism of the reaction through intermolecular hydrogen bonds.

3.
Genes Brain Behav ; : e12828, 2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35906757

RESUMO

The Reln gene encodes for the extracellular glycoprotein Reelin, which regulates several brain functions from development to adulthood, including neuronal migration, dendritic growth and branching and synapse formation and plasticity. Human studies have implicated Reelin signaling in several neurodevelopmental and psychiatric disorders. Mouse studies using the heterozygous Reeler (HR) mice have shown that reduced levels of Reln expression are associated with deficits in learning and memory and increased disinhibition. Although these traits are relevant to substance use disorders, the role of Reelin in cellular and behavioral responses to addictive drugs remains largely unknown. Here, we compared HR mice to wild-type (WT) littermate controls to investigate whether Reelin signaling contributes to the hyperlocomotor and rewarding effects of cocaine. After a single or repeated cocaine injections, HR mice showed enhanced cocaine-induced locomotor activity compared with WT controls. This effect persisted after withdrawal. In contrast, Reelin deficiency did not induce cocaine sensitization, and did not affect the rewarding effects of cocaine measured in the conditioned place preference assay. The elevated cocaine-induced hyperlocomotion in HR mice was associated with increased protein Fos expression in the dorsal medial striatum (DMS) compared with WT. Lastly, we performed an RNA fluorescent in situ hybridization experiment and found that Reln was highly co-expressed with the Drd1 gene, which encodes for the dopamine receptor D1, in the DMS. These findings show that Reelin signaling contributes to the locomotor effects of cocaine and improve our understanding of the neurobiological mechanisms underlying the cellular and behavioral effects of cocaine.

4.
J Child Health Care ; : 13674935221107962, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35703125

RESUMO

In the United Kingdom, the prevalence of children and young people (CYP) accessing acute paediatric inpatient care with mental health problems is increasing, with self-harm and eating disorders particularly prevalent. This study evaluated CYP experiences of being in receipt of acute paediatric inpatient care following either self-harm or crisis stemming from an eating disorder to inform domains for a person-centred outcome measure (PCOM). A series of stakeholder engagement events were conducted between April and July 2015 where creative approaches were used to explore stakeholder experiences of care and to identify outcome domains that were subsequently prioritised using a Nominal Group Technique. Data were analysed using inductive thematic approach, with significance scores calculated for domain statements. Ninety-six stakeholders (15 CYP, eight parents and carers, and 73 professionals) participated. Findings showed five priority PCOM domains: privacy and surveillance; holistic care; making choices, appropriate communication; working together to achieve care goals; and respect and empowerment. This single centre evaluation highlights the need for a PCOM to be developed for this patient group that comprehensively reflects stakeholders' expectations in order to inform improvements to quality of acute paediatric care.

5.
Phys Chem Chem Phys ; 24(29): 17449-17461, 2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35713004

RESUMO

For more than half a century, pericyclic reactions have played an important role in advancing our fundamental understanding of cycloadditions, sigmatropic shifts, group transfer reactions, and electrocyclization reactions. However, the fundamental mechanisms of photochemically activated cheletropic reactions have remained contentious. Here we report on the simplest cheletropic reaction: the [2+1] addition of ground state 18O-carbon monoxide (C18O, X1Σ+) to D2-acetylene (C2D2) photochemically excited to the first excited triplet (T1), second excited triplet (T2), and first excited singlet state (S1) at 5 K, leading to the formation of D2-18O-cyclopropenone (c-C3D218O). Supported by quantum-chemical calculations, our investigation provides persuasive testimony on stepwise cheletropic reaction pathways to cyclopropenone via excited state dynamics involving the T2 (non-adiabatic) and S1 state (adiabatic) of acetylene at 5 K, while the T1 state energetically favors an intermediate structure that directly dissociates after relaxing to the ground state. The agreement between experiments in low temperature ices and the excited state calculations signifies how photolysis experiments coupled with theoretical calculations can untangle polyatomic reactions with relevance to fundamental physical organic chemistry at the molecular level, thus affording a versatile strategy to unravel exotic non-equilibrium chemistries in cyclic, aromatic organics. Distinct from traditional radical-radical pathways leading to organic molecules on ice-coated interstellar nanoparticles (interstellar grains) in cold molecular clouds and star-forming regions, the photolytic formation of cyclopropenone as presented changes the perception of how we explain the formation of complex organics in the interstellar medium eventually leading to the molecular precursors of biorelevant molecules.

6.
Water Res ; 220: 118622, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35613485

RESUMO

Despite the significance of groundwater to the hydrological cycle and as a source of potable water, very little information exists on microplastics (MPs) in this environment. In the present study, MPs have been determined in ten well samples obtained from an alluvial aquifer in a semi-arid region (Shiraz, Iran) following filtration, digestion and inspection under a binocular microscope. A total of 96 MPs were identified, and concentrations ranged from 0.1 to 1.3 MP L-1 (mean and median = 0.48 and 0.43 MP L-1, respectively) and exhibited a complex distribution across the area that reflected differences in land use and local hydrology and geology. The majority of MPs (about 70%) were fibres of ≤ 500 µm in length, but fragments and films were present at some sites, and the dominant polymers were polystyrene, polyethylene and polyethylene terephthalate. Coupling meteorological and water table monitoring data from the regional water organization and published information on aquifer hydrology, we estimate a lag time from precipitation to water table intrusion of between one and five months and groundwater velocity flows of between 0.01 and 0.07 m d-1. Although the extent of retardation of MPs within the pores of groundwater is unknown, by considering empirical data and theoretical predictions on particle flow through porous media in the literature we surmise that MP residence times in the aquifer are likely to range from years to decades, thereby impeding any clear means of source identification. Nevertheless, and more generally, the consumption of potable groundwater may make to a contribution to MP exposure through ingestion.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Monitoramento Ambiental , Irã (Geográfico) , Microplásticos , Plásticos , Poluentes Químicos da Água/análise
7.
Chemosphere ; 303(Pt 2): 134914, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35588874

RESUMO

During the decommissioning and removal of radioactive material in nuclear facilities, fine, tritiated dusts of stainless steel, cement or tungsten are generated that could be accidently released to the environment. However, the potential radio- and ecotoxicological effects these tritiated particles may have are unknown. In this study, stainless steel particles (SSPs) representative of those likely to be tritiated are manufactured by hydrogenation and their tissue-specific bioaccumulation, release (depuration) and subsequent genotoxic response have been studied in the marine mussel, Mytilus galloprovincialis, as a baseline for future assessments of the potential effects of tritiated SSPs. Exposure to 1000 µg L-1 of SSPs and adopting Cr as a proxy for stainless steel revealed relatively rapid accumulation (∼5 h) in the various mussel tissues but mostly in the digestive gland. Over longer periods up to 18 days, SSPs were readily rejected and egested as faecal material. DNA strand breaks, as a measure of genotoxicity, were determined at each time point in mussel haemocytes using single cell gel electrophoresis, or the comet assay. Lack of chemical genotoxicity was attributed to the rapid processing of SSP particles and limited dissolution of elemental components of steel. Further work employing tritiated SSPs will enable radio-toxicology to be studied without the confounding effects of chemical toxicity.


Assuntos
Mytilus , Aço Inoxidável , Animais , Bioacumulação , Ensaio Cometa/métodos , Dano ao DNA
8.
J Alzheimers Dis ; 87(4): 1647-1657, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35527547

RESUMO

BACKGROUND: Genetic variants in TREM2 are strongly associated with Alzheimer's disease (AD) risk but alternative splicing in TREM2 transcripts has not been comprehensively described. OBJECTIVE: Recognizing that alternative splice variants can result in reduced gene expression and/or altered function, we sought to fully characterize splice variation in TREM2. METHODS: Human anterior cingulate autopsy tissue from 61 donors was used for end-point and quantitative PCR and western blotting to identify and quantify novel TREM2 isoforms. RESULTS: In addition to previously described transcripts lacking exon 3 or exon 4, or retaining part of intron 3, we identified novel isoforms lacking exon 2, along with isoforms lacking multiple exons. Isoforms lacking exon 2 were predominant at approximately 10% of TREM2 mRNA in the brain. Expression of TREM2 and frequency of exon 2 skipping did not differ between AD samples and non-AD controls (p = 0.1268 and p = 0.4909, respectively). Further, these novel splice isoforms were also observed across multiple tissues with similar frequency (range 5.3 -13.0%). We found that the exon 2 skipped isoform D2-TREM2 is translated to protein and localizes similarly to full-length TREM2 protein, that both proteins are primarily retained in the Golgi complex, and that D2-TREM2 is expressed in AD and non-AD brain. CONCLUSION: Since the TREM2 ligand binding domain is encoded by exon 2, and skipping this exon retains reading frame while conserving localization, we hypothesize that D2-TREM2 acts as an inhibitor of TREM2 and targeting TREM2 splicing may be a novel therapeutic pathway for AD.


Assuntos
Processamento Alternativo , Encéfalo , Glicoproteínas de Membrana , Receptores Imunológicos , Doença de Alzheimer , Encéfalo/metabolismo , Éxons/genética , Humanos , Ligantes , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo
9.
Antibiotics (Basel) ; 11(4)2022 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-35453201

RESUMO

Gram-positive bacteria do not produce lipopolysaccharide as a cell wall component. As such, the polymyxin class of antibiotics, which exert bactericidal activity against Gram-negative pathogens, are ineffective against Gram-positive bacteria. The safe-for-human-use hydroxyquinoline analog ionophore PBT2 has been previously shown to break polymyxin resistance in Gram-negative bacteria, independent of the lipopolysaccharide modification pathways that confer polymyxin resistance. Here, in combination with zinc, PBT2 was shown to break intrinsic polymyxin resistance in Streptococcus pyogenes (Group A Streptococcus; GAS), Staphylococcus aureus (including methicillin-resistant S. aureus), and vancomycin-resistant Enterococcus faecium. Using the globally disseminated M1T1 GAS strain 5448 as a proof of principle model, colistin in the presence of PBT2 + zinc was shown to be bactericidal in activity. Any resistance that did arise imposed a substantial fitness cost. PBT2 + zinc dysregulated GAS metal ion homeostasis, notably decreasing the cellular manganese content. Using a murine model of wound infection, PBT2 in combination with zinc and colistin proved an efficacious treatment against streptococcal skin infection. These findings provide a foundation from which to investigate the utility of PBT2 and next-generation polymyxin antibiotics for the treatment of Gram-positive bacterial infections.

10.
Environ Res ; 212(Pt B): 113213, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35398314

RESUMO

Despite the importance of agricultural soils, little is known about the fate of microplastics (MPs) in this environment. In the present study, MPs have been determined in soils and wind-eroded sediments from two vegetable-growing fields in the Fars province of Iran, one using plastic mulch for water retention (Field 1) and the other using wastewater for irrigation (Field 2). MPs were heterogeneously distributed in the surface (0-5 cm) and subsurface (5-15 cm) soils of both fields, with a maximum concentration overall of about 1.1 MP g-1 and no significant differences in concentrations between either fields or depths. Fibres represented the principal shape of MPs, but spherules, presumably from wastewater, also made a significant (∼25%) contribution to MPs in Field 2. Analysis of selected samples by Raman spectroscopy and scanning electron microscopy revealed that polyethylene terephthalate (PET) and nylon were the most abundant polymers and that MPs exhibited varying degrees of weathering. Concentrations of MPs in this study are within the range reported previously for agricultural soils, although the absence of PET observed in earlier studies is attributed to the use of insufficiently dense solutions to isolate plastics. Deployment of a portable wind tunnel revealed threshold wind velocities for soil erosion of up to 7 and 12 m s-1 and MP erosion rates up to about 0.4 and 1.1 MP m-2 s-1 for Fields 1 and 2, respectively. Erosion rates are considerably greater than published depositional rates for MPs and suggest that agricultural soils act as both a temporary sink and dynamic secondary source of MPs that should be considered in risk assessments and global transport budgets.


Assuntos
Microplásticos , Solo , Agricultura , Plásticos/análise , Águas Residuárias/análise
11.
Sci Total Environ ; 823: 153721, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35149068

RESUMO

Hypersaline lakes support unique ecosystems and biogeochemistries but are often subject to anthropogenic pressures from pollution, water abstraction-diversion and climate change. Less understood, however, are the inputs, distributions and impacts of microplastics (MPs) in hypersaline environments. In this study, MPs are determined in water and sediment cores of Maharloo Lake, south-west Iran, and in the anthropogenically-impacted rivers that recharge the lake. MP concentrations in river water ranged from 0.05 MP L-1 in the headwaters to about 2 MP L-1 downstream of industrial effluents, with intermediate (but elevated) concentrations observed in the lake. The maximum surface concentration in lake sediment cores was about 860 MP kg-1, and concentrations displayed a progressive reduction with increasing depth down to 50 cm that are qualitatively consistent with temporal changes in plastic production. The size distribution of MPs was skewed towards the finest fraction (< 100 µm) and the most abundant polymer types were polyethylene terephthalate, polyethylene and nylon. Flux calculations using river water data and published atmospheric deposition data for the region reveal that the atmosphere is, by at least an order of magnitude, the more important source. MPs added to the lake appear to be maintained in suspension by high density water but are subsequently deposited to sediments by encapsulation and nucleation as salts precipitate. In addition, it is proposed that direct atmospheric deposition to sediment takes place on areas that seasonally dry out and are subsequently inundated. The impacts of MPs on hypersaline ecosystems and biomass resources are unknown but warrant investigation.


Assuntos
Microplásticos , Poluentes Químicos da Água , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos , Irã (Geográfico) , Lagos , Plásticos , Poluentes Químicos da Água/análise
12.
Environ Pollut ; 301: 118943, 2022 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-35150801

RESUMO

Brominated flame retardants (BFRs) are an important group of additives in plastics that increase resistance to ignition and slow down the rate of burning. Because of concerns about their environmental and human health impacts, however, some of the most widely employed BFRs, including hexabromocyclododecane (HBCD) and commercial mixtures of penta-, octa- and deca- (poly)bromodiphenyl ethers (PBDEs), have been restricted or phased out. In this review, the oceanic sources and pathways of PBDEs, the most widely used BFRs, are evaluated and quantified, with particular focus on emissions due to migration from plastics into the atmosphere versus emissions associated with the input of retarded or contaminated plastics themselves. Calculations based on available measurements of PBDEs in the environment suggest that 3.5 and 135 tonnes of PBDEs are annually deposited in the ocean when scavenged by aerosols and through air-water gas exchange, respectively, with rivers contributing a further ∼40 tonnes. Calculations based on PBDE migration from plastic products in use or awaiting or undergoing disposal yield similar net inputs to the ocean but indicate a relatively rapid decline over the next two decades in association with the reduction in the production and recycling of these chemicals. Estimates associated with the input of PBDEs to the ocean when "bound" to marine plastics and microplastics range from about 360 to 950 tonnes per year based on the annual production of plastics and PBDEs over the past decade, and from about 20 to 50 tonnes per annum based on the abundance and distribution of PBDEs in marine plastic litter. Because of the persistence and pervasiveness of plastics in the ocean and diffusion coefficients for PBDEs on the order of 10-20 to 10-27 m2 s-1, microplastics are likely to act as a long-term source of these chemicals though gradual migration. Locally, however, and more important from an ecotoxicological perspective, PBDE migration may be significantly enhanced when physically and chemically weathered microplastics are exposed to the oily digestive fluids conditions of fish and seabirds.


Assuntos
Retardadores de Chama , Éteres Difenil Halogenados , Monitoramento Ambiental , Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Microplásticos , Plásticos , Reciclagem
13.
Sci Total Environ ; 822: 153451, 2022 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-35114223

RESUMO

Samples of fresh snow (n = 34) have been collected from 29 locations in various urban and remote regions of northern Iran following a period of sustained snowfall and the thawed contents examined for microplastics (MPs) according to established techniques. MP concentrations ranged from undetected to 86 MP L-1 (mean and median concentrations ~20 MP and 12 MP L-1, respectively) and there was no significant difference in MP concentration between sample location type or between different depths of snow (or time of deposition) sampled at selected sites. Fibres were the dominant shape of MP and µ-Raman spectroscopy of selected samples revealed a variety of polymer types, with nylon most abundant. Scanning electron microscopy coupled with energy-dispersive X-ray analysis showed that some MPs were smooth and unweathered while others were more irregular and exhibited significant photo-oxidative and mechanical weathering as well as contamination by extraneous geogenic particles. These characteristics reflect the importance of both local and distal sources to the heterogeneous pool of MPs in precipitated snow. The mean and median concentrations of MPs in the snow samples were not dissimilar to the published mean and median concentrations for MPs in rainfall collected from an elevated location in southwest Iran. However, compared with rainfall, MPs in snow appear to be larger and more diverse in their shape and composition (and include rubber particulates), possibly because of the greater size but lower terminal velocities of snowflakes relative to raindrops. Snowfall represents a significant means by which MPs are scavenged from the atmosphere and transferred to soil and surface waters that warrants further attention.


Assuntos
Microplásticos , Poluentes Químicos da Água , Monitoramento Ambiental , Irã (Geográfico) , Plásticos/análise , Neve , Poluentes Químicos da Água/análise
14.
Phys Chem Chem Phys ; 24(3): 1424-1436, 2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-34982080

RESUMO

NASA's New Horizons mission unveiled a diverse landscape of Pluto's surface with massive regions being neutral in color, while others like Cthulhu Macula range from golden-yellow to reddish comprising up to half of Pluto's carbon budget. Here, we demonstrate in laboratory experiments merged with electronic structure calculations that the photolysis of solid acetylene - the most abundant precipitate on Pluto's surface - by low energy ultraviolet photons efficiently synthesizes benzene and polycyclic aromatic hydrocarbons via excited state photochemistry thus providing critical molecular building blocks for the colored surface material. Since low energy photons deliver doses to Pluto's surface exceeding those from cosmic rays by six orders of magnitude, these processes may significantly contribute to the coloration of Pluto's surface and of hydrocarbon-covered surfaces of Solar System bodies such as Triton in general. This discovery critically enhances our perception of the distribution of aromatic molecules and carbon throughout our Solar System.

15.
Chemosphere ; 292: 133456, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34973256

RESUMO

Dust storms are common events in arid and semi-arid regions that have a wide range of impacts on the environment and human health. This study addresses the presence, characteristics and potential sources of microplastics (MPs) in such events by analysing MPs deposited with dust particles in the metropolis of Shiraz, southwest Iran, following an intense storm in May 2018. At 22 locations throughout the city, MP concentrations on a number basis ranged from 0.04 to 1.06 per g of dust (median = 0.31 MP g-1). Particles were mainly fibrous, with a mean diameter of about 20 µm and >60% under 100 µm in length, and polymer makeup was dominated by nylon, polypropylene and polyethylene terephthalate. Examination of selected MPs by scanning electron microscopy revealed varying degrees of weathering and contamination by extraneous geogenic particles amongst the samples. Using published MP concentrations in urban dusts and remote, arid soils, we estimate that between about 0.1 and 5% of MPs deposited by the dust storm are derived from local sources within the metropolis, with the remainder arising from more distant sources. HYSPLIT modelling, satellite imagery and published geochemical signatures of regional dust particles suggest that the deserts of Saudi Arabia constitute the principal distal and transboundary source. Dust storms may represent a significant means by which MPs are transported and redistributed in arid and semi-arid environments and an important source of MPs to the oceans.


Assuntos
Microplásticos , Plásticos , Cidades , Poeira/análise , Monitoramento Ambiental , Humanos
16.
Harmful Algae ; 111: 102131, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-35016773

RESUMO

Although phytoplankton is ubiquitous in the world's oceans some species can produce compounds that cause damaging effects in other organisms. These include the toxins responsible for paralytic shellfish poisoning, which, in UK waters, are produced by dinoflagellates from the Alexandrium genus. Within Great Britain (GB) a monitoring programme exists to detect this harmful genus as well as the Paralytic Shellfish Poisoning (PSP) toxins in the flesh of shellfish from classified production areas. The techniques used for toxin analysis allow for detailed analysis of the toxin profiles present in contaminated shellfish. It is possible to compare the toxin profiles of contaminated shellfish with the profiles from toxin producing algae and use this information to infer the causative microalgal species responsible for the contamination. This study sought to evaluate the potential for this process within the GB monitoring framework. Two species of toxic Alexandrium, A. catenella from Scotland and A. minutum from Southern England, were fed to mussels (Mytilus sp.) under controlled conditions. The toxin profile in mussels derived from feeding on each species independently, when mixed and when introduced sequentially was analysed and compared to the source algal cultures using K means cluster analysis. Toxin profiles in contaminated shellfish clustered with those of the causative algae and separately from one another during toxin accumulation and, where A. catenella was the sole toxin source, during depuration. During depuration after feeding with A. minutum and where mixed or sequential feeding was undertaken deviant toxin profiles were observed. Finally, data generated within this experimental study were compared to monitoring data from the GB official control programme. These data indicated that the causative algal species in sole source contaminations could be inferred from toxin profile analysis. This technique will be of benefit within monitoring programmes to enhance the value of data with minimal additional expense, where the toxin profiles of causative microalgae have been well described.


Assuntos
Dinoflagelados , Mytilus , Intoxicação por Frutos do Mar , Animais , Toxinas Marinhas/toxicidade , Frutos do Mar/análise
17.
J Phys Chem A ; 126(1): 125-144, 2022 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-34935392

RESUMO

We report the results on the combustion of single, levitated droplets of exo-tetrahydrodicyclopentadiene (JP-10) doped with titanium-aluminum-boron (Ti-Al-B) reactive metal nanopowders (RMNPs) in an oxygen (60%)-argon (40%) atmosphere by exploiting an ultrasonic levitator with droplets ignited by a carbon dioxide laser. Ultraviolet-visible (UV-vis) emission spectroscopy revealed the presence of gas-phase aluminum (Al) and titanium (Ti) atoms. These atoms can be oxidized in the gas phase by molecular oxygen to form spectroscopically detected aluminum monoxide (AlO) and titanium monoxide (TiO) transients. Analysis of the optical ignition videos supports that the nanoparticles are ignited before JP-10. The detection of boron monoxide (BO) further proposes an active surface chemistry through the oxidation of the RMNPs and the release of at least BO into the gas phase. The oxidation of gas-phase BO by molecular oxygen to boron dioxide (BO2) plus atomic oxygen might operate in the gas phase, although the involvement of surface oxidation processes of RMNPs to BO2 cannot be discounted. The UV-vis emission spectra also revealed the key reactive intermediates (OH, CH, C2, and HCO) of the oxidation of JP-10. Electronic structure calculations reveal that the presence of reactive radicals has a profound impact on the oxidation of JP-10. Although titanium monoxide (TiO) reacts to produce titanium dioxide (TiO2), it does not engage in an active JP-10 chemistry as all abstraction pathways are endoergic by more than 217 kJ mol-1. This is similar for atomic aluminum and titanium, whose hydrogen abstraction reactions from JP-10 were revealed to be endoergic by at least 77 kJ mol-1. Therefore, aluminum and titanium react preferentially with molecular oxygen to produce their monoxides. However, the formation of BO, AlO, and BO2 supplies a pool of highly reactive radicals, which can abstract hydrogen from JP-10 via transition states ranging from only 1 to 5 kJ mol-1 above the separated reactants, forming JP-10 radicals along with the hydrogen abstraction products (boron hydride oxide, aluminum monohydroxide, and metaboric acid) in the overall exoergic reactions. These abstraction barriers are well below the barriers of abstractions for ground-state atomic oxygen and molecular oxygen. In this sense, gas-phase BO, AlO, and BO2 catalyze the oxidation of gas-phase JP-10 via hydrogen abstraction, forming highly reactive JP-10 radicals. Overall, the addition of RMNPs to JP-10 not only provides a higher energy density fuel but is also expected to lead to shorter ignition delays compared to pure JP-10 due to the highly reactive pool of radicals (BO, AlO, and BO2) formed in the initial stage of the oxidation process.

18.
Sci Total Environ ; 812: 152308, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34952054

RESUMO

Polypropylene (PP) inkjet cartridges spilled during January 2014 in the northwest Atlantic Ocean from a container ship and subsequently retrieved from beaches around Europe and the Azores along with a matching reference cartridge that had not been exposed to the environment were physically and chemically characterized. Compared with the reference, the cartridges retrieved from the marine environment exhibited considerable cracking-fracturing, discoloration, surface roughness, loss of gloss and staining. Infrared analysis revealed that weathering was highly heterogeneous, with the carbonyl index ranging from <0.1 to >0.9 over areas of sub-mm-dimensions. The high degree of weathering was partly attributed to the presence, quality, and distribution of the titanium dioxide pigment, TiO2. Thus, in the absence of sufficient protection by encapsulation or addition of antioxidants, the ultraviolet light-absorbing pigment promoted the formation of free radicals and photocatalytic oxidation. The results of this study show that consumer plastics containing TiO2 for coloration or tinting purposes, when not designed for exterior use (in the absence of encapsulation or antioxidants), may experience accelerated weathering in the marine environment, and that estimates of plastic persistence should factor in the role of additives that promote photoactivity.


Assuntos
Plásticos , Polipropilenos , Oceano Atlântico , Titânio , Tempo (Meteorologia)
19.
Br J Gen Pract ; 72(715): e128-e137, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34903520

RESUMO

BACKGROUND: Health services are increasingly using digital tools to deliver care, and online consultations are being widely adopted in primary care settings. The intended consequences of online consultations are to increase patient access to care and increase the efficiency of care. AIM: To identify and understand the unintended consequences of online consultations in primary care. DESIGN AND SETTING: Qualitative interview study in eight general practices using online consultation tools in South West and North West England between February 2019 and January 2020. METHOD: Thematic analysis of semi-structured interviews with 19 patients and 18 general practice staff. RESULTS: Consequences of online consultations were identified that restricted patient access to care by making it difficult for some patients to communicate effectively with a GP and disadvantaging digitally-excluded patients. This stemmed from patient uncertainty about how their queries were dealt with, and whether practices used online consultations as their preferred method for patients to contact the practice. Consequences were identified that limited increases in practice efficiency by creating additional work, isolation, and dissatisfaction for some staff. CONCLUSION: Unintended consequences often present operational challenges that are foreseeable and partly preventable. However, these challenges must be recognised and solutions resourced sufficiently. Not everyone may benefit and local decisions will need to be made about trade-offs. Process changes tailored to local circumstances are critical to making effective use of online consultation tools. Unintended consequences also present clinical challenges that result from asynchronous communication. Online consultation tools favour simple, well-formulated information exchange that leads to diffuse relationships and a more transactional style of medicine.


Assuntos
Medicina Geral , Encaminhamento e Consulta , Medicina Geral/métodos , Humanos , Atenção Primária à Saúde/métodos , Pesquisa Qualitativa , Reino Unido
20.
Sci Total Environ ; 806(Pt 1): 150375, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34563907

RESUMO

Non-fibrous microplastics sampled by the Continuous Plankton Recorder (CPR) Survey throughout the North Atlantic Ocean during 2018 have been recorded and a selection (n = 17, or 16.7%) physically and chemically characterised. The average abundance of non-fibrous particles captured by the plankton silks and detectable by microscopy was estimated to be around 0.01 m-3, with the highest concentrations evident in shelf seas of northwest Europe. Amongst the samples analysed, median size was 180 µm and, based on visible properties (e.g., brittleness, layering) and infra-red spectra, all but one were identified as flakes of paint. Semi-quantitative analysis by energy-dispersive X-ray fluorescence spectrometry with a collimated beam revealed that six flakes from European shelf seas were Cu-based antifouling formulations (without evidence of organo-Sn compounds), and five with a broader geographical distribution were Pb-based formulations of likely marine origin. Other elements regularly detected included Cr, Fe, Ti and Zn that were present in pigments or as contaminants from the underlying substrate. After fibres, paint flakes appear to be the most abundant type of microplastic in the oceans that, because of the abundance and mobility of metallic additives, deserve closer scientific attention.


Assuntos
Microplásticos , Poluentes Químicos da Água , Oceano Atlântico , Monitoramento Ambiental , Pintura , Plásticos , Poluentes Químicos da Água/análise
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