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The limited ionic conductivity of polymer electrolytes is a major issue for their industrial application. Enhancement of ionic conductivity in the poly(ethylene oxide), PEO, based electrolyte has been achieved by loading passive nanofillers such as SiO2 nanoparticles (NPs). To investigate the role of modifications in free volume characteristics and the polymer chain dynamics induced by the loading of passive fillers on the ionic conductivity of the PEO based ternary electrolyte, a systematic investigation has been carried out using positron annihilation and broadband dielectric spectroscopy. As a result of interfacial interactions, the loading of SiO2 NPs alters the semi-crystalline morphology of PEO resulting in a higher crystallinity at lower loadings due to the surface confinement of PEO chains, and the formation of smaller PEO crystallites at higher loadings due to interparticle nanoconfinement. These modifications are accompanied by a decrease in free volume fraction at the lowest loading (0.5 wt%) followed by an increase at higher loadings (≥2.0 wt%). The Almond-West formalism considering two different universalities in different temperature and frequency ranges has been used to explain the ion-conduction process at different NP loadings. The Li ion conductivity is observed to be maximum for a 5.0 wt% loading of SiO2 NPs. The enhancement in ionic conductivity is observed to be directly correlated with the free volume characteristics and segmental dynamics of the PEO matrix, confirming their role in ion transport in polymer electrolytes.
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BACKGROUND: Work-related stress, anxiety and depression (WRSAD) are common, overlapping mental health problems burdened with major medical, occupational, institutional and societal implications. Current occupational health (OH) management of WRSAD is based on clinical and managerial guidelines and individual risk assessment. AIMS: The study sought to identify patterns of OH advice in WRSAD and the relationships between the OH advice, available evidence, experience and expertise of the OH doctors (OHDs). METHODS: A retrospective cross-sectional analysis of 101 first-time OH consultations for WRSAD by nine OHDs. RESULTS: The three most common OH interventions included follow-up OH consultations, adjusted duties and referrals for counselling. All OHDs preferred a light-touch approach but the less experienced and qualified OHDs were more proactive and prescriptive. CONCLUSIONS: In the absence of a specific occupational medical guideline for the management of WRSAD, the OH interventions may be guided by clinical guidelines, individual risk assessment, the client's circumstances or the experience, expertise and preferences of the OHDs. In the study group, OH interventions were under-utilized and not consistently applied. Our findings support the argument for OH guideline for WRSAD to improve the consistency and effectiveness of OH interventions. This is important given the scale of the problem and the recent increase in WRSAD during the COVID-19 pandemic.
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COVID-19 , Saúde Ocupacional , Estresse Ocupacional , Estudos Transversais , Humanos , Pandemias , Estudos Retrospectivos , SARS-CoV-2RESUMO
CONTEXT: Thyroid disorders are common in diabetics and related to severe diabetic complications. TRPV2 ion channels have crucial functions in insulin secretion and glucose metabolism which have an important role in the pathophysiology of diabetes. Also, they have a significant effect on various immunological events that are involved in the HT pathophysiology. OBJECTIVE: This study aimed to investigate rs14039 and rs4792742 polymorphisms of the TRPV2 ion channels in type 2 diabetes mellitus (T2DM, n=100) Hashimoto thyroiditis (HT, n=70) and comorbid T2DM and HT (T2DM+HT, n=100) patients and control (n=100). DESIGN: Case-control study. SUBJECT AND METHODS: RT-PCR genotyping was used to determine rs14039 and rs4792742 polymorphisms with DNA samples of subjects and appropriate primer and probes. Besides, required biochemical analyses were performed. RESULTS: It was determined that the frequencies of the rs14039 GG homozygote polymorphic genotype and the G allele were significantly higher in T2DM+HT patients compared to the control (p=0.03 and p=0.01, respectively) and that especially the GG genotype increases the risk of T2DM+HT 3.046-fold (p=0.01, OR=3.046). It was detected that the GG genotype increased the risk of HT 2.54-fold (p=0.05, OR=2.541). TRPV2 rs4792742 polymorphisms reduce the risk of HT and T2DM+HT comorbidity almost by half and have a protective effect against HT and T2DM+HT. CONCLUSION: The rs14039 GG genotype of the TRPV2 gene significantly increases the risks of development of T2DM+HT and HT disorders, may have a significant role in the pathophysiology of these diseases, also leading to predisposition for their development. Conversely, rs4792742 polymorphic genotypes have a strong protective effect against the HT and T2DM+HT comorbidity.
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OBJECTIVE: The aim of this study was to: (a) screen a large group of unselected patients with juvenile systemic lupus erythematosus for anti-aquaporin 4 antibodies (AQP4-Ab); (b) identify clinical and laboratory predictors of the presence of AQP4-Ab positivity in juvenile systemic lupus erythematosus. METHODS: Sera from 90 patients with juvenile systemic lupus erythematosus were tested for the presence of AQP4-Ab using a cell-based assay. Demographics, clinical and immunological features, treatment received were summarized. Fisher's exact test was used to identify clinical predictors of positivity for AQP4-Ab. RESULTS: Five of 90 (5.5%) patients tested positive for AQP4-Ab, all of which had neurological involvement, mainly transverse myelitis and optic neuritis. AQP4-Ab-positive patients were more likely to have neurological symptoms (P = 0.002), less likely to experience dermatological manifestations (P = 0.045), and less likely to have detectable anti-dsDNA antibodies (P = 0.022). These patients were also more likely to have received anti-epileptic (P = 0.023) and anti-coagulant (P = 0.007) drugs. CONCLUSIONS: The findings of this study indicate that some patients with juvenile systemic lupus erythematosus develop antibodies against aquaporin-4 and may be at risk of developing a neurological clinical phenotype. We suggest that all juvenile systemic lupus erythematosus patients should be systematically screened for the presence of AQP4-Ab and this may help identify a high risk for neurological involvement in juvenile systemic lupus erythematosus.
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Aquaporina 4/sangue , Imunoglobulina G/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Adolescente , Adulto , Aquaporina 4/imunologia , Criança , Feminino , Humanos , Lúpus Eritematoso Sistêmico/complicações , Masculino , Mielite Transversa/diagnóstico , Mielite Transversa/etiologia , Neurite Óptica/diagnóstico , Neurite Óptica/etiologia , Estudos Retrospectivos , Adulto JovemRESUMO
The large number of potential applications of ionic liquids (ILs) requires an understanding of their environmental impacts including their adverse effects on microorganisms living in soil and water. The molecular mechanism of toxic activities of these liquids is yet to be understood in detail. Any foreign molecules, interacting with an organism, have to encounter first the cellular membrane, which is predominantly composed of the lipid bilayer. In this work, multilamellar vesicles (MLV) of phospholipids have been used to shed light on the effect of an IL on the structure of a cellular membrane. The MLVs formed by the zwitterionic lipid, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) are found to shrink as a consequence of interaction with an imidazolium-based IL, 1-decyl-3-methylimidazolium tetrafluoroborate ([DMIM] [BF4]). The absorbed ILs significantly modify the surface charge of the MLVs. While these observations indicate a strong membrane-IL interaction, synchrotron-based small angle X-ray diffraction (SAXD) measurements provide a structural description of the interaction. SAXD and Fourier transform infrared spectroscopy studies clearly reveal a disordering effect of the IL on the conformational organization of the lipid chains. The presence of the negatively charged lipid 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine sodium salt (DPPS) in MLVs plays an important role in disordering the chains in the membrane and inter-bilayer interactions.
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Membrana Celular/química , Líquidos Iônicos/química , Membranas Artificiais , Fosfolipídeos/química , Temperatura , Hidrodinâmica , Imidazóis/química , Bicamadas Lipídicas/química , Conformação MolecularRESUMO
An Artificial Intelligence system was developed and implemented for water, wastewater, and reuse plants to improve management of sensors, short and long-term maintenance plans, asset and investment management plans. It is based on an integrated approach to capture data from different computer systems and files. It adds a layer of intelligence to the data. It serves as a repository of key current and future operations and maintenance conditions that a plant needs have knowledge of. With this information, it can simulate the configuration of processes and assets for those conditions to improve or optimize operations, maintenance and asset management, using the IViewOps (Intelligent View of Operations) model. Based on the optimization through model runs, it is able to create output files that can feed data to other systems and inform the staff regarding optimal solutions to the conditions experienced or anticipated in the future.
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Inteligência Artificial , Tomada de Decisões , Instalações de Eliminação de Resíduos , Humanos , Estações do Ano , Eliminação de Resíduos Líquidos , Tempo (Meteorologia)RESUMO
In this study, the accumulation of some heavy metals in spiny eel (Mastacembelus mastacembelus Banks and Solander, 1794) living in Karakaya Dam Lake was determined and human health risk of this fish when consumed as food was examined. For this purpose, the amounts of copper (Cu), chromium (Cr), cadmium(Cd), iron (Fe), zinc (Zn) in water samples and in the muscle tissues of the fishes were determined. The amounts of heavy metals showed differences in the muscle tissues of Mastacembelus mastacembelus according to weight, length, sex and age groups of fish. In conclusion the amounts of heavy metals in the flesh of spiny eels were found lower than that recommended by EPA, WHO, FAO and TFC.
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Monitoramento Ambiental , Peixes/metabolismo , Metais Pesados/análise , Saúde Pública , Animais , Peso Corporal , Feminino , Geografia , Masculino , Músculos , Especificidade da Espécie , Turquia , Poluentes Químicos da Água/análiseRESUMO
BACKGROUND: Primary adrenal insufficiency (PAI) is a rare and severe condition requiring lifelong steroid replacement. During acute illness or stressful events, it is important to appropriately adjust glucocorticoid dose; failure to do so may lead to an adrenal crisis. The aim of the study was to explore patients PAI knowledge and understanding of the condition, steroid replacement adjustment during acute illness or stress and provided education. METHODS: Ten adult patients with PAI were purposefully recruited from two hospitals in a tertiary NHS Trust in England, UK. Data was collected using a mixed method approach utilising semi-structured audio-recorded interviews and hospital case note review. Interviews were transcribed verbatim and analysed using Burnard's content analysis framework. Information from the hospital case note review was captured using a matrix table based on pre-defined criteria. RESULTS: Four key themes emerged: 'Addison's disease and hydrocortisone replacement'; 'stress and corticosteroids'; 'patient compliance/adherence' and 'transition'. Patients reported feelings of 'going through a transition from uncertainty to adaption' following diagnosis. All participants had a good level of knowledge and understanding of required medication however application in times of need was poor. Medication adherence and prevention of a crisis relied not only on patient knowledge and application but also the support of family and health professionals. Health care professional knowledge required improvement to aid diagnosis and management of PAI. CONCLUSION: Patients with PAI did not apply existing knowledge to adjust steroid dose during acute illness or stress. Although a sample of limited size, our study identified there is a need to further explore why patients with Addison's disease do not apply existing knowledge during times of increased need. Future research should consider appropriate behaviour change interventions to promote medication adherence to reduce risk of an adrenal crisis.
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Doença de Addison/psicologia , Insuficiência Adrenal/psicologia , Conhecimentos, Atitudes e Prática em Saúde , Terapia de Reposição Hormonal/psicologia , Adesão à Medicação/psicologia , Educação de Pacientes como Assunto , Doença de Addison/terapia , Insuficiência Adrenal/terapia , Adulto , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Adulto JovemRESUMO
BACKGROUND: Postgraduate education, training and clinical governance in occupational medicine (OM) require easily accessible yet rigorous, research and evidence-based tools based on actual clinical practice. AIMS: To develop and evaluate an online resource helping physicians develop their OM skills using their own cases of work-related ill-health (WRIH). METHODS: WRIH data reported by general practitioners (GPs) to The Health and Occupation Research (THOR) network were used to identify common OM clinical problems, their reported causes and management. Searches were undertaken for corresponding evidence-based and audit guidelines. A web portal entitled Electronic, Experiential, Learning, Audit and Benchmarking (EELAB) was designed to enable access to interactive resources preferably by entering data about actual cases. EELAB offered disease-specific online learning and self-assessment, self-audit of clinical management against external standards and benchmarking against their peers' practices as recorded in the research database. The resource was made available to 250 GPs and 224 occupational physicians in UK as well as postgraduate OM students for evaluation. RESULTS: Feedback was generally very favourable with physicians reporting their EELAB use for case-based assignments. Comments such as those suggesting a wider range of clinical conditions have guided further improvement. External peer-reviewed evaluation resulted in accreditation by the Royal College of GPs and by the Faculties of OM (FOM) of London and of Ireland. CONCLUSIONS: This innovative resource has been shown to achieve education, self-audit and benchmarking objectives, based on the participants' clinical practice and an extensive research database.
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Educação a Distância , Educação Médica Continuada/métodos , Medicina do Trabalho/educação , Benchmarking , Guias como Assunto , Humanos , Internet , Médicos , Reino UnidoRESUMO
Understanding how a tiny dilute evaporative colloidal spray droplet gets transformed into a microgranule with a characteristic morphology is crucial from scientific as well as technological points of view. In the present work, it is demonstrated that the morphology and the size distribution of the microcapsules can be tuned simply by adjusting the drying temperature. Shape and size of the capsules are quantified at four different drying temperatures. It is shown that the morphology transits gradually from sphere to toroid with increasing temperature keeping the average volume-fraction of the correlated nanoparticles nearly unaffected for the synthesized granules. A plausible mechanism for the chronological pathway of such morphological transformation is illustrated. Computer simulation corroborates the experimentally observed morphological transition. The variation in hollowness and buckling tendency of the capsules are elucidated by scattering and imaging techniques.
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BACKGROUND: Periodic health surveillance (HS) of workers can identify early cases of occupational asthma. Information about its uptake and its content in the UK is lacking. AIMS: To identify the overall levels of uptake and quality of HS for occupational asthma within three high-risk industry sectors in the UK. METHODS: A telephone survey of employers, and their occupational health (OH) professionals, carried out in three sectors with exposures potentially capable of causing occupational asthma (bakeries, wood working and motor vehicle repair). RESULTS: A total of 457 organizations participated (31% response rate). About 77% employed <10 people, 17% between 10 and 50 and 6% >50. Risk assessments were common (67%) and 14% carried out some form of HS for occupational asthma, rising to 19% if only organizations reporting asthma hazards and risks were considered. HS was carried out both by in-house (31%) and external providers (69%). Organizational policies were often used to define HS approaches (80%), but infrequently shared with the OH provider. OH providers described considerable variation in practice. Record keeping was universal, but worker-held records were not reported. HS tools were generally developed in-house. Lung function was commonly measured, but only limited interpretation evident. Referral of workers to local specialist respiratory services was variable. CONCLUSIONS: This study provided new insights into the real world of HS for occupational asthma. We consider that future work could and should define simpler, more practical and evidence-based approaches to HS to ensure maximal consistency and use of high-quality approaches.
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Poluentes Ocupacionais do Ar/efeitos adversos , Asma/diagnóstico , Asma/etiologia , Doenças Profissionais/epidemiologia , Exposição Ocupacional/efeitos adversos , Asma/epidemiologia , Humanos , Doenças Profissionais/etiologia , Medição de Risco/métodos , Inquéritos e Questionários , Ensino/normasRESUMO
In-situ scanning small-angle X-ray scattering (SAXS) experiments have been performed to probe the drying of a single suspended droplet of silica colloids. It has been demonstrated that the formation of a nanoparticle shell during drying can be confirmed just by measuring the temporal evolution of the spatial transmission profile across the drying droplet. The shrinkage of the droplet stops once the shell is formed. The temporal dependence of the shell thickness and droplet radius has been estimated by quantitative analysis of the functionality of the transmission profiles. It is revealed that the position of the correlation peak originating from interactions between silica nanoparticles evolves linearly during the initial stage of drying and exhibits sigmoidal growth behavior in later stages. The interaction between colloidal particles in different drying stages has been investigated. We provide experimental confirmation of the transition from repulsive interaction to a capillary-driven short-range attraction during shell formation. The present work demonstrates that in-situ scanning SAXS on a suspended droplet is an invaluable technique for monitoring the dynamic self-organization of colloids as it probes the drying of complex fluids without the interference of a substrate.
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BACKGROUND: The generic term asbestos refers to a group of crystalline mineral silicates that occur naturally in various forms. Because of their properties of strength, heat and electrical resistance and their ability to withstand corrosion by acids and sea water, asbestos was used extensively both in the UK and worldwide. AIMS: To provide a historical perspective of this ubiquitous occupational hazard, consider the key changes in UK legislation aimed at improving the management of this occupational health risk and describe the evidence from the scientific literature concerning asbestos and disease. METHODS: Original articles, reviews (including reference textbooks) and scientific literature in PubMed and other principal medical science databases, 1960-2014, were searched. Publications by regulatory agencies and by governmental organizations were also considered and included where relevant. RESULTS: Asbestos remains the biggest cause of cancer deaths worldwide. For malignant mesothelioma deaths alone, it is estimated that in the UK, between 2015 and 2020, the number of cases will peak at 2500 cases annually. It is not clear whether there is a safe level of asbestos fibres in air. Evidence for the efficacy of health surveillance is lacking. CONCLUSIONS: Although the use of asbestos was banned in the UK in 1985 (amosite and crocidolite) and 1999 (chrysotile), it remains a significant occupational risk factor for work-related morbidity and mortality, causing both benign and malignant diseases, often with long latency. Further research is needed regarding exposure levels and health surveillance.
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Amianto/efeitos adversos , Asbestose/epidemiologia , Indicadores Básicos de Saúde , Exposição Ocupacional/legislação & jurisprudência , Exposição Ocupacional/estatística & dados numéricos , Asbestose/complicações , Asbestose/diagnóstico , Humanos , Exposição Ocupacional/efeitos adversos , Ocupações/tendências , Trabalho/normas , Trabalho/estatística & dados numéricos , Trabalho/tendênciasRESUMO
BACKGROUND: Consistent evidence from population studies report that 10-15% of the total burden of chronic obstructive pulmonary disease (COPD) is associated with workplace exposures. This proportion of COPD could be eliminated if harmful workplace exposures were controlled adequately. AIMS: To produce a standard of care for clinicians, occupational health professionals, employers and employees on the identification and management of occupational COPD. METHODS: A systematic literature review was used to identify published data on the prevention, identification and management of occupational COPD. Scottish Intercollegiate Guidance Network grading and the Royal College of General Practitioner three star grading system were used to grade the evidence. RESULTS: There are a number of specific workplace exposures that are established causes of COPD. Taking an occupational history in patients or workers with possible or established COPD will identify these. Reduction in exposure to vapours, gases, dusts and fumes at work is likely to be the most effective method for reducing occupational COPD. Identification of workers with rapidly declining lung function, irrespective of their specific exposure, is important. Individuals can be identified at work by accurate annual measures of lung function. CONCLUSIONS: Early identification of cases with COPD is important so that causality can be considered and action taken to reduce causative exposures thereby preventing further harm to the individual and other workers who may be similarly exposed. This can be achieved using a combination of a respiratory questionnaire, accurate lung function measurements and control of exposures in the workplace.
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Doenças Profissionais/terapia , Doença Pulmonar Obstrutiva Crônica/terapia , Padrão de Cuidado , Poeira , Humanos , Equipamento de Proteção Individual , Fatores de Risco , Fumar/efeitos adversos , Inquéritos e QuestionáriosRESUMO
Colloidal particles in a tiny drying droplet are forced to assemble due to attractive capillary forces. Jamming of the particles throughout the droplet remains either isotropic or anisotropic depending upon the drying kinetics and the physicochemical environment. In this work, we explore the dynamical evolution of such an assembly process across a single evaporative droplet by in situ scanning small-angle scattering using a micro-focused X-ray beam at the synchrotron source. A methodology has been elucidated to differentiate quantitatively between the isotropic and the anisotropic jamming process. Switching of jamming behaviour depending on the initial particle volume fraction in the droplet has been demonstrated. Three distinct stages of assembly, associated with droplet shrinkage, have been revealed even during isotropic jamming. This is in contrast to the drying of a pure liquid droplet under diffusion limited evaporation. It has been established that such in situ scattering measurements can also be used to estimate the temporal evolutions of the viscosity of a drying suspension as well as the diffusivity of nanoparticles in a droplet.
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OBJECTIVE: To determine whether a midwife-led intervention improved preparation for twin parenting and maternal psychosocial outcome. DESIGN: Randomised controlled trial. SETTING: Two maternity units in North East England. POPULATION: A cohort of 162 women with uncomplicated twin pregnancy. METHODS: Self-completion questionnaire at multiple time points. MAIN OUTCOME MEASURES: The primary outcome was probable postnatal depression (measured with the Edinburgh Postnatal Depression Scale, EPDS) 26 weeks after delivery. Secondary outcomes included preparation for parenting, maternal anxiety, parenting stress, and maternal wellbeing. RESULTS: The mean maternal EPDS scores at 26 weeks after delivery were 5.4 (SD 4.5) in the twin intervention (TI) group and 6.9 (SD 5.5) in the twin control (TC) group, and the mean difference between the groups was 1.5 (95% confidence interval, 95% CI, -0.2 to 3.3). The relative risk (RR) of having probable depression in the TI group compared with the TC group at 26 weeks was 0.48 (95% CI 0.19-1.20) for mothers and 0.84 (95% CI 0.42-1.70) for fathers. There were no statistically significant differences in maternal anxiety or parenting stress. TI mothers reported increased maternal wellbeing, reaction to motherhood, family support, mood, and greater self-confidence 26 weeks after delivery, and felt more prepared for parenting. CONCLUSION: As a result of the limited sample size, the study was unable to detect a difference in maternal depression using the maternal EPDS mean score. The antenatal preparation for parenting programme did not improve postnatal maternal anxiety or parenting stress; however, it did improve postnatal maternal wellbeing, mood, self-confidence, reaction to motherhood, and better prepared mothers to parent twin infants. Midwives have a key role in preparing mothers to parent twins.
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Depressão Pós-Parto/epidemiologia , Bem-Estar Materno/psicologia , Tocologia , Poder Familiar/psicologia , Pais/psicologia , Estresse Psicológico/epidemiologia , Adaptação Psicológica , Transtornos de Ansiedade/epidemiologia , Inglaterra , Feminino , Humanos , Masculino , Gravidez , Inquéritos e Questionários , GêmeosRESUMO
The diagnosis of occupational contact dermatitis (OCD) and occupational contact urticaria (OCU) is a process that involves fastidious clinical and occupational history taking, clinical examination, patch testing and skin-prick testing. A temporal relationship of work and/or the presence of a rash on the hands only raises suspicion of an occupational cause, and does not necessarily confirm an occupational causation. The identification of allergy by patch or prick tests is a major objective, as exclusion of an offending allergen from the environment can contribute to clinical recovery in the individual worker and avoidance of new cases of disease. This can be a complex process where allergens and irritants, and therefore allergic and irritant contact dermatitis, may coexist. This article provides guidance to healthcare professionals dealing with workers exposed to agents that potentially cause OCD and OCU. Specifically it aims to summarize the 2010 British Occupational Health Research Foundation (BOHRF) systematic review, and also to help practitioners translate the BOHRF guideline into clinical practice. As such, it aims to be of value to physicians and nurses based in primary and secondary care, as well as occupational health and public health clinicians. It is hoped that it will also be of value to employers, interested workers and those with responsibility for workplace standards, such as health and safety representatives. Note that it is not intended, nor should it be taken to imply, that these standards of care override existing statutory and legal obligations. Duties under the U.K. Health and Safety at Work Act 1974, the Management of Health and Safety at Work Regulations 1999, the Control of Substances Hazardous to Health Regulations 2002, the Equality Act 2010 and other relevant legislation and guidance must be given due consideration, as should laws relevant to other countries.
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Atenção à Saúde/normas , Dermatite Ocupacional/terapia , Saúde Ocupacional/normas , Urticária/terapia , Alérgenos/efeitos adversos , Atitude do Pessoal de Saúde , Dermatite Ocupacional/etiologia , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Irritantes/efeitos adversos , Educação de Pacientes como Assunto/métodos , Guias de Prática Clínica como Assunto , Padrão de Cuidado , Reino Unido , Urticária/etiologiaRESUMO
Micrometric grains of anisotropic morphology have been achieved by evaporation-induced self-assembly of silica nanoparticles. The roles of polymer concentration and its molecular weight in controlling the buckling behavior of drying droplets during assembly have been investigated. Buckled doughnut grains have been observed in the case of only silica colloid. Such buckling of the drying droplet could be arrested by attaching poly(ethylene glycol) on the silica surface. The nature of buckling in the case of only silica as well as modified silica colloids has been explained in terms of theory of homogeneous elastic shell under capillary pressure. However, it has been observed that colloids, modified by polymer with relatively large molecular weight, gives rise to buckyball-type grains at higher concentration and could not be explained by the above theory. It has been demonstrated that the shell formed during drying of colloidal droplet in the presence of polymer becomes inhomogeneous due to the presence of soft polymer rich zones on the shell that act as buckling centers, resulting in buckyball-type grains.
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The evaporation-induced self-assembly of mixed colloids has been employed to synthesize microspheres of TiO(2)/SiO(2) nanocomposites. Small-angle neutron/X-ray scattering and scanning electron microscopy experiments reveal the hierarchical morphology of the microspheres. Although the internal structure of the microspheres, consisting of solely silica nanoparticles, gets significantly modified with time because of the reduction in the high specific surface area by internal coalescence, the same for the composite microspheres remains stable over an aging time of 1 year. Such temporal stability of the composite microspheres is attributed to the inhibition of coalescence of the silica nanoparticles in the presence of titania nanoparticles. X-ray diffraction and thermogravimetric results show the improved thermal stability of the composite grains against the anatase-to-rutile phase transition. Such thermal stability is attributed to the suppression of the growth of titania nanoparticles in the presence of silica nanoparticles. The UV-vis results indicate the confinement effect of the TiO(2) nanoparticles in the silica matrix. A plausible mechanism has been elucidated for the formation of microspheres with different morphology during self-assembly.
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BACKGROUND: Lead has been recognized increasingly as a public health risk, although with the introduction of wide-ranging occupational and public health measures, levels of blood lead in the general population of the UK and other developed nations have been in decline in recent years. Nonetheless, cases of lead poisoning still occur. METHODS: We report on a large cluster of exposed lead workers and their families, including several children. The focus of the occupational and public health investigations was to identify the different groups at risk and the pathways by which potential exposures were taking place. RESULTS: Lead in the workplace was found to account for the raised blood lead levels amongst the workers with exposure occurring as a result of insufficient demarcation between 'clean' and 'dirty' areas, and from contamination of personal belongings with lead. Furthermore, there was evidence of para-occupational exposure of family members. CONCLUSIONS: The successful control of lead in this case required multidisciplinary working. Efforts included extensive workplace controls, along with the education and care of workers and their families, though complicated by lack of familiarity with the UK health service amongst the affected groups, language barriers, underlying low levels of literacy and high mobility.