Experimental investigation of paraffin-based fuels for hybrid rocket propulsion

Solid fuels for hybrid rockets were characterized in the framework of a research project aimed to develop a new generation of solid fuels, combining at the same time good mechanical and ballistic properties. Original techniques were implemented in order to improve paraffin-based fuels. The first strengthening technique involves the use of a polyurethane foam (PUF); a second technique is based on thermoplastic polymers mixed at molecular level with the paraffin binder. A ballistic characterization of paraffin-based hybrid rocket solid fuels was performed, considering pure wax-based fuels and fuels doped with suitable metal additives. Nano-Al powders and metal hydrides (magnesium hydride (MgH2), lithium aluminum hydride (LiAlH4 )) were used as fillers in paraffin matrices. The results of this investigation show a strong correlation between the measured viscosity of the melted paraffin layer and the regression rate: a decrease of viscosity increases the regression rate. This trend is due to the increasing development of entrainment phenomena, which strongly increase the regression rate. Addition of LiAlH4 (mass fraction 10%) can further increase the regression rate up to 378% with respect to the pure HTPB regression rate, taken as baseline reference fuel. The highest regression rates were found for the Solid Wax (SW) composition, added with 5% MgH2 mass fraction; at 350 kg/(m2s) oxygen mass flux, the measured regression rate, averaged in space and time, was 2.5 mm/s, which is approximately five times higher than that of the pure HTPB composition. Compositions added with nanosized aluminum powders were compared with those added with MgH2, using gel or solid wax

Otimização da utilização de marcadores moleculares microssatélites e sua aplicação em estudos com plantas daninhas.

Nota técnica

Population trends of the fan mussel Pinna nobilis from Portofino MPA (Ligurian Sea, Western Mediterranean Sea) before and after a mass mortality event and a catastrophic storm

Two Pinna nobilis populations thriving inside the borders of the Portofino Marine Protected Area (MPA) (Ligurian Sea, western Mediterranean Sea) were monitored before (2012) and after (September 2018) a dire mass mortality event that, since September 2016, spread through the whole Mediterranean Sea. In Portofino MPA, recorded mortality rates reached values of 91.29% and 43.94% in the two populations. The presence of a Haplosporidium protozoan parasite, considered to be the main cause of the mortality episodes, was confirmed from histological evidence: sporocysts and plasmodia were observed in all the tubules of the digestive glands of the collected specimens. Moreover, a catastrophic storm hit the Ligurian coasts at the end of October 2018, causing considerable damages both below and above the surface; a new survey conducted in November 2018 showed the complete annihilation of the two studied populations, as a probable combination of the continued parasite infections and the mechanical impacts caused by the storm. Finally, in June 2020 the sites were monitored again looking for traces of recovery, but no new specimens were recorded, indicating that P. nobilis became virtually absent from the MPA

Análise da estrutura populacional e determinação do fluxo gênico entre populações de arroz vermelho.

objetivo do trabalho foi caracterizar geneticamente populações de arroz vermelho do RS com suspeita de resistência aos herbicidas imidazolinonas e elucidar aspectos relacionados ao fluxo gênico de sementes entre diferentes locais

Social-ecological features of set nets small-scale fisheries in the context of Mediterranean marine protected areas

The small-scale fisheries (SSF) sector has attracted considerable attention over the last decade due to its major importance in sustaining the livelihoods of coastal communities worldwide, poverty alleviation, food security, social wealth and traditions. Despite this importance, quantitative and qualitative information on SSF is still largely lacking and when available, it tends to be scattered or very localized. SSF are also among the very few professional extractive activities generally allowed within Marine Protected Areas (MPAs), and are therefore expected to acquire further momentum in the near future in light of the projected increase of protected marine surface area due to international commitments. However, SSF associated with areas including MPAs may differ from those operating in unprotected contexts with regard to a range of socio-ecological aspects, thus potentially making management strategies currently in force unsuitable, and requiring the development of ad hoc local and regional policies. Here, we assessed the socio-ecological dimension of SSF operating within and around 11 Mediterranean MPAs, in six EU countries, with the aim of identifying relevant patterns that could inform policy and management relative to this fishing sector in view of the forthcoming increase of the marine surface area under protection. To do so, we have adopted a collaborative approach with fishers and combined a photo-sampling survey of 1,292 set net (mainly trammel-nets) fishing operations at landing with 149 semi-structured interviews with fishers, to gather information on features and catches of SSF fleets (e.g. vessel characteristics, gears, catch composition, catch and revenue per unit of effort). Overall, results highlighted: 1) multiple shared features emerging at regional level (i.e. among the 11 study areas), such as the predominant use of set nets, the major contribution of a limited number of species to the overall catch and revenue, the occurrence in the catch of threatened species and/or undersized individuals; 2) a variety of distinctive socio-ecological features differentiating local SSF communities such as the species mainly contributing to catch and revenue, species size distribution and fleet characteristics. In addition to presenting elements to inform common policies and strategies for SSF management in the context of MPAs, our study provides guidance for the development of a standard methodology for the full documentation of SSF in the Mediterranean Sea