Understanding cost escalation in nuclear reactor construction projects

This work seeks to evaluate overnight construction costs (OCC) and lead time escalation of nuclear reactors from 1955 to 2016. To this end, a comprehensive database of commercial Light Water Reactors (LWR) was developed and a statistical analysis was conducted. Findings reveal that there is significant delay in lead time, especially for the last generation reactors constructed from 2010’s. This results in the escalation of capital costs rather than a decline. Average OCC of newer reactors are 60% higher than the ones implemented in the earlier stages of the nuclear era. This suggests a negative learning curve effect for both OCC and lead time, which threats the market and financial sustainability of current and future nuclear energy projects. Although this is a general trend, this negative effect is country specific and, thus, induced by national policies and regulatory frameworks. Therefore, the role of nuclear technology to cope with the decarbonisation of the power sector must be better evaluated, taking into account the real cost impacts of nuclear technology implementation.This work was also funded by the Brazilian research funding agency CNPq.This work was funded by the Brazilian research funding agency CNPq and the Marie Curie International Research Staff Exchange Scheme Fellowship within the 7th European Union Framework Programme, under the project NETEP- European Brazilian Network on Energy Planning (PIRSES-GA-2013-612263)

Low-carbon scenarios for the Brazilian power system

The Brazilian power generation sector faces a paradigm change driven, on one hand, by a shift from a hydropower dominated mix and, on the other, by international goals for reducing greenhouse gases emissions. The objective of this work was to evaluate five scenarios for the Brazilian power system until 2050 using a multi-criteria decision analysis tool. These scenarios include a baseline trend and low carbon policy scenarios based on carbon taxes and carbon emission limits. To support the applied methodology, a questionnaire was elaborated to integrate the perceptions of experts on the scenario evaluation process. Taking into account the results from multi-criteria analysis, scenario preference followed the order of increasing share of renewables in the power system. The preferable option for the future Brazilian power system is a scenario where wind and biomass have a major contribution. The robustness of the multi-criteria tool applied in this study was tested by a sensitivity analysis. This analysis demonstrated that, regardless the respondents’ preferences and backgrounds, scenarios with higher shares of fossil fuel sources are the least preferable option, while scenarios with major contributions from wind and biomass are the preferable option to supply electricity in Brazil through 2050.This research was supported by a Marie Curie International Research Staff Exchange Scheme Fellowship within the 7th European Union Framework Programme, under project NETEP- European Brazilian Network on Energy Planning (PIRSES-GA-2013-612263)

Structure and Mechanism of Dimer-Monomer Transition of a Plant Poly(A)-Binding Protein upon RNA Interaction: Insights into Its Poly(A) Tail Assembly

Poly(A)-binding proteins (PABPs) play crucial roles in mRNA biogenesis, stability, transport and translational control in most eukaryotic cells. Although animal PABPs are well-studied proteins, the biological role, three-dimensional structure and RNA-binding mode of plant PABPs remain largely uncharacterized. Here, we report the structural features and RNA-binding mode of a Citrus sinensis PABP (CsPABPN1). CsPABPN1 has a domain architecture of nuclear PABPs (PABPNs) with a single RNA recognition motif (RRM) flanked by an acidic N-terminus and a GRPF-rich C-terminus. The RRM domain of CsPABPN1 displays virtually the same three-dimensional structure and poly(A)-binding mode of animal PABPNs. However, while the CsPABPN1 RRM domain specifically binds poly(A), the full-length protein also binds poly(U). CsPABPN1 localizes to the nucleus of plant cells and undergoes a dimer–monomer transition upon poly(A) interaction. We show that poly(A) binding by CsPABPN1 begins with the recognition of the RNA-binding sites RNP1 and RNP2, followed by interactions with residues of the β2 strands, which stabilize the dimer, thus leading to dimer dissociation. Like human PABPN1, CsPABPN1 also seems to form filaments in the presence of poly(A). Based on these data, we propose a structural model in which contiguous CsPABPN1 RRM monomers wrap around the RNA molecule creating a superhelical structure that could not only shield the poly(A) tail but also serve as a scaffold for the assembly of additional mRNA processing factors

The antimicrobial polymer PHMB enters cells and selectively condenses bacterial chromosomes

To combat infection and antimicrobial resistance, it is helpful to elucidate drug mechanism(s) of action. Here we examined how the widely used antimicrobial polyhexamethylene biguanide (PHMB) kills bacteria selectively over host cells. Contrary to the accepted model of microbial membrane disruption by PHMB, we observed cell entry into a range of bacterial species, and treated bacteria displayed cell division arrest and chromosome condensation, suggesting DNA binding as an alternative antimicrobial mechanism. A DNA-level mechanism was confirmed by observations that PHMB formed nanoparticles when mixed with isolated bacterial chromosomal DNA and its effects on growth were suppressed by pairwise combination with the DNA binding ligand Hoechst 33258. PHMB also entered mammalian cells, but was trapped within endosomes and excluded from nuclei. Therefore, PHMB displays differential access to bacterial and mammalian cellular DNA and selectively binds and condenses bacterial chromosomes. Because acquired resistance to PHMB has not been reported, selective chromosome condensation provides an unanticipated paradigm for antimicrobial action that may not succumb to resistance

Estimativa de sequestro de carbono por árvores em um sistema integrado de produção agropecuária em área de proteção ambiental no subtrópico brasileiro.

Edição especial dos resumos do IUFRO World Congress, 25., 2019, Curitiba