Radiationless anapole states in on-chip photonics

High-index nanoparticles are known to support radiationless states called anapoles, where dipolar and toroidal moments interfere to inhibit scattering to the fa...     

O3R: Ontology-based mechanism for a human-centered environment targeted at the analysis of navigation patterns

Web Usage Mining (WUM) is the application of data mining techniques over Web server logs in order to extract navigation usage patterns. The analysis of mining patterns for assessing the knowledge they reveal is a critical phase in WUM. The main challenges are: (a) mining algorithms yield a huge number of patterns and (b) there is a significant semantic gap between URLs and events performed by users. In this paper, we describe the pattern analysis mechanisms integrated in O3R (Ontology-based Rules Retrieval and Rummaging), a human-centered environment for the analysis of navigation rules. O3R explores the synergy of mechanisms for retrieving and analyzing patterns. Filtering and clustering allow users to retrieve subsets of patterns with specific characteristics, in order to deal with the large volume of patterns. Rummaging mechanisms are targeted at assessing the meaning and relevance of pattern with regard to the domain, and it is particularly suitable for exploratory analysis. The distinctive feature of O3R is that is dynamically associates meaning to patterns using the concepts and relationships of a domain ontology, as a means of reducing the gap between syntactic URLs and semantic events performed by users. The paper describes the mechanisms in detail, and explores their synergic integration in the O3R prototype. It also reports two case studies that evaluate the use of O3R for the analysis of navigation patterns of a learning site.     

Chemical Defenses Against Fish Predation in Three Brazilian Octocorals: 11β,12β-Epoxypukalide as a Feeding Deterrent in Phyllogorgia dilatata

The feeding-deterrence properties of crude extracts of three Brazilian octocoral species, Neospongodes atlantica Kükenthal (Alcyonacea, Nephtheidae), Plexaurella regia Castro (Gorgonacea, Plexauridae), and Phyllogorgia dilatata Esper (Gorgonacea, Gorgoniidae), were investigated. All the extracts were incorporated into food strips at the concentrations occurring in the living organisms. Crude extract and its ethyl acetate fraction obtained from P. dilatata collected in Armação dos Búzios (Rio de Janeiro State), when incorporated into artificial diets and tested in the habitat of origin, reduced consumption of food strips by fishes, relative to controls. Crude extracts from two octocoral species collected at the National Marine Park of Abrolhos (Bahia State), N. atlantica and P. regia, had no apparent feeding-deterrence properties; in fact, they seemed to stimulate feeding. Bioassay-guided fractionation of the bioactive P. dilatata crude extract revealed that the deterrent property was restricted to a medium polarity fraction. Field palatability experiments with two pure compounds isolated from this fraction revealed that the furanocembranolide 11,12-epoxypukalide is a potent feeding deterrent produced by P. dilatata against fish. Apparently, furanocembranolides are a particular class of compounds with feeding deterrent properties, protecting some octocorals from potential fish predator species in both tropical and temperate environments.     

Comparison of Methodologies for the Extraction of Bacterial DNA from Mussels—Relevance for Food Safety

The control of the microbiological quality of bivalve molluscs assumes particular importance because they are among the most produced seafood products and mostly consumed as a whole, raw, or lightly cooked. The composition of the bacterial community associated with bivalves depends mostly on the microbiology of the surrounding environment at growing sites. Once the relationship between microbiology of bivalves and environment is established, a better classification and monitoring of the shellfish beds and evaluation of depuration strategies can be achieved. In this work, we tested if the methods of DNA extraction commonly used for the culture-independent microbiological analysis of sediment and water could be used directly, or with modifications, for the analysis of bacteria in mussels. The commercial kits Genomic DNA Purification Kit (MBI Fermentas, Vilnius, Lithuania), UltraClean^TM Soil DNA Isolation Kit (MOBIO Laboratories, Inc., Carlsbad, CA) and the method described by Griffiths and collaborators for DNA/RNA co-extraction were compared. The efficiency of extraction was assessed by DNA fluorescence and the denaturing gradient gel electrophoresis gel patterns of 16S ribosomal RNA gene fragments were used to compare the reproducibility and representativeness of the extraction methods. Results showed that the DNA/RNA co-extraction method with modifications was the most suitable. However, the results must be interpreted in the light of the purpose of the study and the relevance of maximizing extraction yield or diversity estimate, without compromising reproducibility. To our knowledge, this was the first attempt to transpose the procedure currently used for DNA extraction from sediments or waters, to the analysis of whole mussels.     

Polysaccharide‐based membranes loaded with erythromycin for application as wound dressings

In this study, the antibiotic erythromycin (Ery) was incorporated into chitosan (Ch)–alginate (A) and Ch–xanthan (X) membranes with the aim of using them as bioactive wound dressings. Drug incorporation was performed by direct addition (DA) to the polysaccharide mixture and by membrane impregnation in solution (IS). A higher incorporation efficiency was obtained for DA, but higher amounts of drug were loaded into membranes by the IS method (maxima ≈ 2.1 and 0.7 g/g for Ch–X and Ch–A, respectively) because the initial concentration of drug could be higher than that in the DA method. Ery release in phosphate‐buffered saline was slow, reaching about 12 and 32 mg of drug/g of membrane in 60 h for Ch–X and 4 and 16 mg/g for Ch–A by the DA and IS methods, respectively. With formulations prepared with IS, the required therapeutic dosage was reached within 60 h, whereas for those incorporating the drug by DA, prolonged use would be required. Both membrane types behaved as drug reservoirs, providing continuous antibiotic release to the wound site. Formulations with higher drug contents showed effective antibacterial activity against two species of bacteria commonly found in skin lesions, Staphylococcus aureus and Pseudomonas aeruginosa, and were thus potentially capable of protecting the wound site from bacterial attack. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43428.     

Geometrical characterization of fluorescently labelled surfaces from noisy 3D microscopy data

Modern fluorescence microscopy enables fast 3D imaging of biological and inert systems alike. In many studies, it is important to detect the surface of objects and quantitatively characterize its local geometry, including its mean curvature. We present a fully automated algorithm to determine the location and curvatures of an object from 3D fluorescence images, such as those obtained using confocal or light‐sheet microscopy. The algorithm aims at reconstructing surface labelled objects with spherical topology and mild deformations from the spherical geometry with high accuracy, rather than reconstructing arbitrarily deformed objects with lower fidelity. Using both synthetic data with known geometrical characteristics and experimental data of spherical objects, we characterize the algorithm's accuracy over the range of conditions and parameters typically encountered in 3D fluorescence imaging. We show that the algorithm can detect the location of the surface and obtain a map of local mean curvatures with relative errors typically below 2% and 20%, respectively, even in the presence of substantial levels of noise. Finally, we apply this algorithm to analyse the shape and curvature map of fluorescently labelled oil droplets embedded within multicellular aggregates and deformed by cellular forces.     

The Impact of [C16Pyr][Amp] on the Aggressiveness in Breast and Prostate Cancer Cell Lines

Breast (BrCa) and prostate (PCa) cancers are the most common malignancies in women and men, respectively. The available therapeutic options for these tumors are still not curative and have severe side effects. Therefore, there is an urgent need for more effective antineoplastic agents. Herein, BrCa, PCa, and benign cell lines were treated with two ionic liquids and two quinoxalines and functional experiments were performed—namely cell viability, apoptosis, cytotoxicity, and colony formation assays. At the molecular level, an array of gene expressions encompassing several molecular pathways were used to explore the impact of treatment on gene expression. Although both quinoxalines and the ionic liquid [C2OHMIM][Amp] did not show any effect on the BrCa and PCa cell lines, [C16Pyr][Amp] significantly decreased cell viability and colony formation ability, while it increased the apoptosis levels of all cell lines. Importantly, [C16Pyr][Amp] was found to be more selective for cancer cells and less toxic than cisplatin. At the molecular level, this ionic liquid was also associated with reduced expression levels of CPT2, LDHA, MCM2, and SKP2, in both BrCa and PCa cell lines. Hence, [C16Pyr][Amp] was shown to be a promising anticancer therapeutic agent for BrCa and PCa cell lines.