Impacts of small dams on the phytoplankton and invertebrates in an Amazonian river

The construction of small hydroelectric plants (SHPs) has increased greatly worldwide, and the impacts of these impoundments can cause changes in the aquatic biota. Here, we investigated the ecological attributes (abundance, richness, and species diversity) of three communities (phytoplankton, invertebrates in the water column, and benthos) and the functional groups of phytoplankton, before and after the construction of five SHPs in an Amazonian river. The communities were sampled at two sites, one upstream and another downstream of each dam or construction site, before the dam closure. The dam did not change the limnological factors, and the acid waters and low electrical conductivity, typical of “cerrado” rivers, were characteristic of both the pre- and post-dam phases. For aquatic communities, the phytoplankton abundance increased and the diversity of groups decreased in the post-dam phase. Regarding the morphology-based functional groups (MBFG), there was an increase in groups I (small algae with a high surface/volume ratio) and V (phytoflagellates), with a reduction in groups VI (diatoms) and VII (large mucilaginous colonies) in the post-dam phase. The relative abundance of zooplankton species increased in the post-dam phase, and the opposite was observed for the benthic community, with reductions in abundance, richness, and group diversity in the post-dam phase. The structure of the three communities differed between the pre- and post-dam phases, but no difference in communities' similarity was observed between the upstream and downstream sites in both phases. The results show that the change in hydrodynamics, from lotic to semi-lentic, in the reservoirs of the SHPs, was the main driving force for the alterations in the three communities. For phytoplankton, SHPs are favorable in the sense of decreasing the incidence of algal blooms, particularly of cyanobacteria.     

Physiological features of periodontal regeneration and approaches for periodontal tissue engineering utilizing periodontal ligament cells

Experimental studies have shown that the potential of periodontal regeneration seems to be limited by the regenerative capacity of the cells involved. The regeneration of damaged periodontal tissues is mediated by various periodontal cells and is regulated by a vast array of extracellular matrix informational molecules that induce both selective and nonselective responses in different cell lineages and their precursors. In this paper, we first review periodontal ligament tissue and its different cell subpopulations including fibroblasts and paravascular stem cells, and their functions during the development and homeostasis of periodontal tissues. Because conventional periodontal regeneration methods remain insufficient to obtain a complete and reliable periodontal regeneration, the concept of periodontal tissue engineering has been based on the generation of the conditions necessary to improve the healing of periodontal tissues. Additionally, the potential of periodontal ligament cells for use in periodontal tissue engineering to overcome the limitations of conventional periodontal regenerative therapies is discussed, followed by an update of the recent progress and future directions of research utilizing periodontal ligament cells for predictable periodontal regeneration.     

In vitro invasiveness and intracellular survival of Salmonella strains isolated from the aquatic environment

Salmonella has a life cycle between the host and the external environment where it is exposed to stressful conditions that may affect its virulence. In this study, we compared the capability of two aquatic (S. Oranienburg S76 and Saintpaul S70) and one clinical isolates (S. Oranienburg S347) to adhere and invade epithelial cells, and to survive within macrophages. S76 and S70, were less adherent to Caco‐2 cells than S347, but they were more invasive. The intracellular survival and growth of S76 in macrophages was increased with time, while S347 showed the highest peak value and S70 survived at moderate levels. Induced cell death in infected epithelial cells and macrophages revealed no differences between all strains. In conclusion, the contrasting responses detected between environmental and clinical isolates could indicate the importance of the distinct adaptation conditions of the strains to the isolation environment that could differentially affect their interaction with the host.     

Real-space imaging of inelastic Friedel-like surface oscillations emerging from molecular adsorbates

We report real space imaging measurements of inelastic Friedel oscillations. The inelastic electron tunneling spectroscopy, using scanning tunneling microscopy, around dimers of dichlorobenze adsorbates on Au(111) surface display clear spatial modulations that we attribute to inelastic scattering at the molecular sites caused by molecular vibrations. Due to local interactions between the adsorbate and the surface states, the molecular vibrations generate a redistribution of the charge density at energies in a narrow range around the inelastic mode. Our experimental findings are supported by theoretical arguments.     

Potential Ecological Roles of Artemisinin Produced by Artemisia annua L.

Artemisia annua L. (annual wormwood, Asteraceae) and its secondary metabolite artemisinin, a unique sesquiterpene lactone with an endoperoxide bridge, has gained much attention due to its antimalarial properties. Artemisinin has a complex structure that requires a significant amount of energy for the plant to synthesize. So, what are the benefits to A. annua of producing this unique compound, and what is the ecological role of artemisinin? This review addresses these questions, discussing evidence of the potential utility of artemisinin in protecting the plant from insects and other herbivores, as well as pathogens and competing plant species. Abiotic factors affecting the artemisinin production, as well as mechanisms of artemisinin release to the surroundings also are discussed, and new data are provided on the toxicity of artemisinin towards soil and aquatic organisms. The antifungal and antibacterial effects reported are not very pronounced. Several studies have reported that extracts of A. annua have insecticidal effects, though few studies have proven that artemisinin could be the single compound responsible for the observed effects. However, the pathogen(s) or insect(s) that may have provided the selection pressure for the evolution of artemisinin synthesis may not have been represented in the research thus far conducted. The relatively high level of phytotoxicity of artemisinin in soil indicates that plant/plant allelopathy could be a beneficial function of artemisinin to the producing plant. The release routes of artemisinin (movement from roots and wash off from leaf surfaces) from A. annua to the soil support the rationale for allelopathy.     

Bactericidal and Anticorrosion Properties in PVK/MWNT Nanocomposite Coatings on Stainless Steel

A PVK/MWNT nanocomposite coating on stainless steel is developed and tested for antimicrobial and anticorrosion properties. The coating is prepared via electrochemical deposition onto SS surfaces and is monitored using cyclic voltammetry. High‐resolution XPS measurements of the C 1s and N 1s regions are used to estimate the film composition. AFM shows a homogeneous thin film of several µm thickness with well‐defined globular domains. The bactericidal functionality of the electrodeposited film is demonstrated by its antibacterial activity against Escherichia coli, even with low MWNT loading (≈6%). The excellent anticorrosion property of the coating is demonstrated after 7 d of exposure to NaCl (0.5 M ) solution.

     

Inference of lexical ontologies. The LeOnI methodology

In this article we present a method for semi-automatically deriving lexico-conceptual ontologies in other languages, given a lexico-conceptual ontology for one language and bilingual mapping resources. Our method uses a logistic regression model to combine mappings proposed by a set of classifiers (up to 17 in our implementation). The method is formally described and evaluated by means of two implementations for semi-automatically building Spanish and Thai WordNets using Princeton's WordNet for English and conventional English-Spanish and English-Thai bilingual dictionaries.