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1.
Environ Manage ; 62(4): 740-755, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29947967

RESUMO

Altered hydrological, sediment, and nutrient regimes can lead to dramatic increases in periphyton abundance in rivers below impoundments. Flushing flows are a commonly adopted strategy to manage the excess periphyton that can accumulate, but in practice they often prove ineffective. Designing hydrological regimes that include flushing flows may be overlooking key processes in periphyton removal, particularly the role of abrasion and molar action induced by substrate movement. Setting flow targets which aim to initiate substrate movement are likely to improve periphyton removal, but an understanding of the site-specific thresholds for substrate entrainment and periphyton removal is required. Despite decades of entrainment studies accurate and consistent measurement and prediction of substrate entrainment remains elusive, making it challenging to study the relationship between substrate movement and periphyton removal, and to set flow targets. This paper makes a case for using substrate entrainment and transport thresholds as the target metric for flushing flows to manage excess periphyton accrual. This paper critically reviews the determinants of periphyton accrual and associated management methods. This paper also aims to provide a reference for interdisciplinary research on periphyton removal by summarising the geomorphic and hydraulic literature on methods for estimating and measuring substrate entrainment and transport. This will provide a basis for ecologists to identify tools for quantifying entrainment and transport thresholds so they are better placed to explore the direct linkages between phases of sediment transport and periphyton accrual. These linkages need to be identified in order for river managers to set effective flushing flow targets.


Assuntos
Conservação dos Recursos Hídricos/métodos , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Perifíton , Rios/química , Movimentos da Água , Hidrologia
2.
ACS Appl Mater Interfaces ; 8(34): 22190-5, 2016 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-27500662

RESUMO

Layered materials, especially the transition metal dichalcogenides (TMDs), are of interest for a broad range of applications. Among the class of TMDs, molybdenum disulfide (MoS2) is perhaps the most studied because of its natural abundance and use in optoelectronics, energy storage and energy conversion applications. Understanding the fundamental structure-property relations is key for tailoring the enhancement in the above-mentioned applications. Here, we report a controlled powder vaporization synthesis of MoS2 flower-like structures consisting of vertically grown layers of MoS2 exhibiting exposed edges. This growth is readily achievable on multiple substrates, such as graphite, silicon, and silicon dioxide. The resulting MoS2 flowers are highly crystalline and stoichiometric. Further observations using contact angle indicate that MoS2 flowers exhibit the highest reported contact angle of ∼160 ± 10°, making the material super hydrophobic. This surface wettability was further tuned by changing the edge chemistry of the MoS2 flowers using an ozone etching treatment. Hydrogen evolution reaction (HER) measurements indicate that the surface treated with UV-ozone showed a reduction in the Tafel slope from 185 to 54 mV/dec, suggesting an increase in the amount of reactive surface to generate hydrogen.

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