Suchergebnisse

AbstractIncidental ultrafine particles (UFPs) constitute a key pollutant in industrial workplaces. However, characterizing their chemical properties for exposure and toxicity assessments still remains a challenge. In this work, the performance of an aerosol concentrator (Versatile Aerosol Concentration Enrichment System, VACES) was assessed to simultaneously sample UFPs on filter substrates (for chemical analysis) and as liquid suspensions (for toxicity assessment), in a high UFP concentration scenario. An industrial case study was selected where metal-containing UFPs were emitted during thermal spraying of ceramic coatings. Results evidenced the comparability of the VACES system with online monitors in terms of UFP particle mass (for concentrations up to 95 µg UFP/m3) and between filters and liquid suspensions, in terms of particle composition (for concentrations up to 1000 µg/m3). This supports the applicability of this tool for UFP collection in view of chemical and toxicological characterization for incidental UFPs. In the industrial setting evaluated, results showed that the spraying temperature was a driver of fractionation of metals between UF (<0.2 µm) and fine (0.2–2.5 µm) particles. Potentially health hazardous metals (Ni, Cr) were enriched in UFPs and depleted in the fine particle fraction. Metals vaporized at high temperatures and concentrated in the UF fraction through nucleation processes. Results evidenced the need to understand incidental particle formation mechanisms due to their direct implications on particle composition and, thus, exposure. It is advisable that personal exposure and subsequent risk assessments in occupational settings should include dedicated metrics to monitor UFPs (especially, incidental).

In this work, metal-insulator-semiconductor structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al2O3), silicon nitride, and silicon oxide (SiOx) to be used as passivation layers in Cu(In,Ga)Se-2 (CIGS) thin-film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties of the CIGS-insulator interface, capacitance versus conductance and voltage (C-G-V) measurements were done to estimate the number and polarity of fixed insulator charges (Q(f)). The density of interface defects (D-it) was estimated from capacitance versus conductance and frequency (C-G-f) measurements. This study evidences that the deposition of the insulators at high temperatures (300 degrees C) and the use of a sputtering technique cause surface modification on the CIGS surface. We found that, by varying the SiOx deposition parameters, it is possible to have opposite charges inside the insulator, which would allow its use in different device architectures. The material with lower Dit values was Al2O3 when deposited by sputtering. ; This work was supported by European Union's Horizon 2020 research and innovation programme ARCIGS-M project under Grant 720887. The work of J. M. V. Cunha and P. M. P. Salome was supported by the Fundacao para a Ciencia e a Tecnologia (FCT) through the project IF/00133/2015. The work of J. P. Teixeira and J. P. Leitao was supported by the FCT through the project UID/CTM/50025/2013. The work of B. Vermang was supported by the European Research Council under the European Union's Horizon 2020 research and innovation programme under Grant 715027.

Objective: To analyse the GARD perspective on the health effects of outdoor air pollution, and to synthesise the Portuguese epidemiological contribution to knowledge on its respiratory impact. Results: Ambient air pollution has deleterious respiratory effects which are more apparent in larger, densely populated and industrialised countries, such as Canada, Iran, Brazil and Portugal, but it also affects people living in low-level exposure areas. While low- and middle-income countries (LMICs), are particularly affected, evidence based on epidemiological studies from LMICs is both limited and heterogeneous. While nationally, Portugal has a relatively low level of air pollution, many major cities face with substantial air pollution problems. Time series and cross-sectional epidemiological studies have suggested increased respiratory hospital admissions, and increased risk of respiratory diseases in people who live in urban areas and are exposed to even a relatively low level of air pollution. Conclusions: Adverse respiratory effects due to air pollution, even at low levels, have been confirmed by epidemiological studies. However, evidence from LMICs is heterogeneous and relatively limited. Furthermore, longitudinal cohort studies designed to study and quantify the link between exposure to air pollutants and respiratory diseases are needed. Worldwide, an integrated approach must involve multi-level stakeholders including governments (in Portugal, the Portuguese Ministry of Health, which hosts GARD-Portugal), academia, health professionals, scientific societies, patient associations and the community at large. Such an approach not only will garner a robust commitment, establish strong advocacy and clear objectives, and raise greater awareness, it will also support a strategy with adequate measures to be implemented to achieve better air quality and reduce the burden of chronic respiratory diseases (CRDs).

In the past years, the strategies used to break the Cu(In,Ga)Se-2 (CIGS) light to power conversion efficiency world record value were based on improvements of the absorber optoelectronic and crystalline properties, mainly using complex post-deposition treatments. To reach even higher efficiency values, further advances in the solar cell architecture are needed, in particular, with respect to the CIGS interfaces. In this study, we evaluate the structural, morphological and optoelectronic impact of an Al2O3 layer as a potential front passivation layer on the CIGS properties, as well as an Al2O3 tunneling layer between CIGS and CdS. Morphological and structural analyses reveal that the use of Al2O3 alone is not detrimental to CIGS, although it does not resist to the CdS chemical bath deposition. The CIGS optoelectronic properties degrade when the CdS is deposited on top of Al2O3. Nonetheless, when Al2O3 is used alone, the optoelectronic measurements reveal a positive impact of this inclusion such as a very low concentration of interface defects while keeping the same CIGS recombination channels. Thus, we suggest that an Al2O3 front passivation layer can be successfully used with alternative buffer layers. Depth-resolved microscopic analysis of the CIGS interface with slow-muons strongly suggests for the first time that low-energy muon spin spectroscopy (LE-mu SR) is sensitive to both charge carrier separation and bulk recombination in complex semiconductors. The demonstration that Al2O3 has the potential to be used as a front passivation layer is of significant importance, considering that Al2O3 has been widely studied as rear interface passivation material. (C) 2020 Published by Elsevier Ltd. ; This work was supported in part by NovaCell (028075) and InovSolarCells (029696) and in part by FunrIa(do para a Ciencia c a Tecnologia and the ERDF through COMPETE2020. Fundacao para a Ciencia e a Tecnologia (FCT) is further acknowledged through 1F/00133/2015, PD/BD/142780/2018 and SFREHBD/1/1677G/2019. The European Union's Horizon 2020 research and innovation programme ARCIGS-M project (Grant agreement 720887) is also acknowledged. The financial support by National Funds through the FCT -Fundacao para a Ciencia e a Tecnologia, I.P., under the scope of the projects MB/50025/2020 and UIDP/50025/2020 -Programatico, are acknowledged. W. C. thanks the individual grant financed by the SusPhotoSolutions project CENTRO-01-0145-FEDER-000005. P. A. Fernandes would like to acknowledge FCT for the support of the project FCT UIDB/04730/2020. This work was supported with funds from FEDER (Programa Operacional Factores de Competitividade COMPETE) and from FCT [Fundacao para a Ciencia e Tecnologia (Portugal)] under Projects No. UID/FIS/04564/2016 and No. PTDC/FIS-MAC/29696/2017. The muon experiments were performed at the Swiss Muon Source SO, Paul Scherrer Institute, Villigen, Switzerland. The authors would like to thanks to Dr. Guy Brammertz for the helping in the interpretation of the TRPL data. ; Curado, MA (corresponding author), INL, Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal. marco.alberto@inl.int