Seismic behaviour of traditional timber frame walls: experimental results on unreinforced walls

Timber frame buildings are well known as an efficient seismic resistant structure and they are used worldwide. Moreover, they have been specifically adopted in codes and regulations during the XVIII and XIX centuries in the Mediterranean area. These structures generally consist of exterior masonry walls with timber elements embedded which tie the walls together and internal walls which have a timber frame with masonry infill and act as shearwalls. In order to preserve these structureswhich characterizemany cities in theworld it is important to better understand their behaviour under seismic actions. Furthermore, historic technologies could be used even in modern constructions to build seismic resistant buildings using more natural materials with lesser costs. Generally, different types of infill could be applied to timber frame walls depending on the country, among which brick masonry, rubble masonry, hay and mud. The focus of this paper is to study the seismic behaviour of the walls considering different types of infill, specifically: masonry infill, lath and plaster and timber frame with no infill. Static cyclic tests have been performed on unreinforced timber frame walls in order to study their seismic capacity in terms of strength, stiffness, ductility and energy dissipation. The tests showed how in the unreinforced condition, the infill is able to guarantee a greater stiffness, ductility and ultimate capacity of the wall.

Análise da disponibilidade de investimento em projetos de reabilitação portugueses

The importance of implementing sustainable practices in buildings is duly proved and understood by the majority of the population. However, its implementation is not yet a reality. Some studies have been performed with the goal of understand this lack of use of sustainable solutions, among building sector stakeholders. The conclusion is that one of the main factors contributing to this is related with economic constraints. Several studies have proven that many sustainable practices correspond to minor costs than traditional practices in a life cycle perspective. However, the building sector stakeholders are not aware of this and do not implement sustainable practices commonly. In this paper a costâ benefit methodology willing to cross this barrier and promote the sustainable practices implementation is presented.

Terahertz response of patterned epitaxial graphene

We study the interaction between polarized terahertz (THz) radiation and micro-structured large-area graphene in transmission geometry. In order to efficiently couple the radiation into the two-dimensional material, a lateral periodic patterning of a closed graphene sheet by intercalation doping into stripes is chosen. We observe unequal transmittance of the radiation polarized parallel and perpendicular to the stripes. The relative contrast, partly enhanced by Fabry-Perot oscillations reaches 20 %. The effect even increases up to 50 % when removing graphene stripes in analogy to a wire grid polarizer. The polarization dependence is analyzed in a large frequency range from < 80 GHz to 3 THz, including the plasmon-polariton resonance. The results are in excellent agreement with theoretical calculations based on the electronic energy spectrum of graphene and the electrodynamics of the patterned structure

Effect of sulfate and iron (III) on LCFA degradation by a methanogenic community

[Excerpt] Under anaerobic conditions long chain fatty acids (LCFA) can be converted to methane by syntrophic bacteria and methanogenic archaea. LCFA degradation was also reported in the presence of alternative hydrogenotrophic partners, such as sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB), which generally show higher affinity for H2 than methanogens and are more resistant to LCFA [1,2,3]. Their presence in a microbial culture degrading LCFA can be advantageous to reduce LCFA toxicity towards methanogens, although high concentrations of external electron acceptor (EEA) can lead to outcompetition of methanogens and cease methane production. In this work, we tested the effect of adding sub-stoichiometric concentrations of sulfate and iron(III) to methanogenic communities degrading LCFA. (...)

Energy production from lipids by novel anaerobes

[Excerpt] Anaerobic microbial diversity encloses a very high potential that can be used for biotechnological applications. This potential is still largely unexplored, since the majority of the microorganisms in Nature are unknown or poorly characterized. This work is focused on the study of novel anaerobic microorganisms that participate in the metabolism of lipids, long chain fatty acids (LCFA) and glycerol, with the main goal of producing valuable energy-rich organic compounds. For that, conventional anaerobic culturing procedures were combined with continuous bioreactors operation and allied to microbial ecology approaches. Two main examples of the work performed will be presented. (...)

Who is who in anaerobic oil biodegradation?

[Excerpt] Anaerobic bioremediation is an important alternative for the common aerobic cleanup of subsurface petroleum-contaminated soil and water. Microbial communities involved in anaerobic oil biodegradation are scarcely studied, and only few mechanisms of anaerobic hydrocarbons degradation are described. In this work, microbial degradation of aliphatic hydrocarbons (AHC) was studied by using culture-dependent and culture-independent approaches. Hexadecane and hexadecene-degrading microbial communities were enriched under sulfate-reducing and methanogenic conditions. The microorganisms present in the enriched cultures were identified by 16S rRNA gene sequencing. (...)

Proteomic analysis of nitrate-dependent acetone degradation by Alicycliphilus denitrificans strain BC

Alicycliphilus denitrificans strain BC grows anaerobically on acetone with nitrate as electron acceptor. Comparative proteomics of cultures of A. denitrificans strain BC grown on either acetone or acetate with nitrate was performed to study the enzymes involved in the acetone degradation pathway. In the proposed acetone degradation pathway, an acetone carboxylase converts acetone to acetoacetate, an AMP-dependent synthetase/ligase converts acetoacetate to acetoacetyl-CoA, and an acetyl-CoA acetyltransferase cleaves acetoacetyl-CoA to two acetyl-CoA. We also found a putative aldehyde dehydrogenase associated with acetone degradation. This enzyme functioned as a -hydroxybutyrate dehydrogenase catalyzing the conversion of surplus acetoacetate to -hydroxybutyrate that may be converted to the energy and carbon storage compound, poly--hydroxybutyrate. Accordingly, we confirmed the formation of poly-?-hydroxybutyrate in acetone-grown cells of strain BC. Our findings provide insight in nitrate-dependent acetone degradation that is activated by carboxylation of acetone. This will aid studies of similar pathways found in other microorganisms degrading acetone with nitrate or sulfate as electron acceptor.

Anaerobic oxidation of methane associated with sulfate reduction in a natural freshwater gas source

The occurrence of anaerobic oxidation of methane (AOM) and trace methane oxidation (TMO) was investigated in a freshwater natural gas source. Sediment samples were taken and analyzed for potential electron acceptors coupled to AOM. Long-term incubations with 13C-labeled CH4 (13CH4) and different electron acceptors showed that both AOM and TMO occurred. In most conditions, 13C-labeled CO2 (13CO2) simultaneously increased with methane formation, which is typical for TMO. In the presence of nitrate, neither methane formation nor methane oxidation occurred. Net AOM was measured only with sulfate as electron acceptor. Here, sulfide production occurred simultaneously with 13CO2 production and no methanogenesis occurred, excluding TMO as a possible source for 13CO2 production from 13CH4. Archaeal 16S rRNA gene analysis showed the highest presence of ANME-2a/b (ANaerobic MEthane oxidizing archaea) and AAA (AOM Associated Archaea) sequences in the incubations with methane and sulfate as compared with only methane addition. Higher abundance of ANME-2a/b in incubations with methane and sulfate as compared with only sulfate addition was shown by qPCR analysis. Bacterial 16S rRNA gene analysis showed the presence of sulfate-reducing bacteria belonging to SEEP-SRB1. This is the first report that explicitly shows that AOM is associated with sulfate reduction in an enrichment culture of ANME-2a/b and AAA methanotrophs and SEEP-SRB1 sulfate reducers from a low-saline environment.