Supramolecular ionics: electric charge partition within polymers and other non-conducting solids

Electrostatic phenomena in insulators have been known for the past four centuries, but many related questions are still unanswered, for instance: which are the charge-bearing species in an electrified organic polymer, how are the charges spatially distributed and which is the contribution of the electrically charged domains to the overall polymer proper-ties? New scanning probe microscopies were recently introduced, and these are suitable for the mapping of electric potentials across a solid sample thus providing some answers for the previous questions. In this work, we report results obtained with two of these techniques: scanning electric potential (SEPM) and electric force microscopy (EFM). These results were associated to images acquired by using analytical electron microscopy (energy-loss spectroscopy imaging in the transmission electron microscope, ESI-TEM) for colloid polymer samples. Together, they show domains with excess electric charges (and potentials) extending up to hundreds of nanometers and formed by large clusters of cations or anions, reaching supramolecular dimensions. Domains with excess electric charge were also observed in thermoplastics as well as in silica, polyphosphate and titanium oxide particles. In the case of thermoplastics, the origin of the charges is tentatively assigned to their tribochemistry, oxidation followed by segregation or the Mawell-Wagner-Sillars and Costa Ribeiro effects.73449551

BIOECOLOGY AND MANAGEMENT OF ERVA-MATE BORER, Hedypathes betulinus (KLUG, 1825) (COLEOPTERA: CERAMBYCIDAE)

A cultura da erva-mate ( Ilex paraguariensis A.St.-Hil.) apresenta grande import\ue2ncia social, cultural e econ\uf4mica no sul do Brasil. Com a forma\ue7\ue3o de povoamentos puros e o aumento da \ue1rea de plantio, observou-se um aumento populacional de muitas esp\ue9cies de insetos. Dentre os insetos-praga, a broca-da-erva-mate, Hedypathes betulinus (Klug, 1825) (Coleoptera: Cerambycidae), \ue9 a de maior import\ue2ncia econ\uf4mica, em raz\ue3o dos danos que causa e seu dif\uedcil controle. A fase larval ocorre no interior dos galhos e troncos das plantas, dificultando sua detec\ue7\ue3o e manejo. O manejo cultural e o mec\ue2nico s\ue3o os mais indicados, como a coleta de adultos, poda e queima de partes atacadas da planta, nutri\ue7\ue3o equilibrada, densidade adequada de plantas e manuten\ue7\ue3o de \ue1reas com vegeta\ue7\ue3o nativa ou ainda a introdu\ue7\ue3o do policultivo. Com essas t\ue9cnicas, espera-se um maior equilibrio do agroecossistema e, com isso, a diminui\ue7\ue3o dos insetos-praga a um n\uedvel aceit\ue1vel. Portanto, o objetivo deste trabalho \ue9 reunir e discutir as informa\ue7\uf5es da bioecologia e manejo da broca-da-erva-mate.The erva-mate ( Ilex paraguariensis A.St.-Hil.) has a social, cultural and economic importance in the southern states of Brazil. The pure stands of this culture was responsible for the increase of many species of insects. Hedypathes betulinus (Klug, 1825) (Coleoptera: Cerambycidae) is considered the main pestfrom an economic viewpoint because of its difficult control and potential for damage. The larval phase occurs inside the twings and trunks, what makes more difficult to deal with its detention and management. Cultural and mechanical management are the most indicated, such as collection of adults, prunning and burning of plant parts damaged by the insect, balanced nutrition, adequate plant density and maintenance of areas with native vegetation or also the introduction of policulture. These strategies may increase the agroecossystem balance and thus a reduction of the insect-pest to an aceptable level. Therefore, the objective of this study was to assemble and the discuss the information on the bioecology and management of erva-mate borer

Ab-initio study of model guanine assemblies: The role of pi-pi coupling and band transport

Several assemblies of guanine molecules are investigated by means of first-principle calculations. Such structures include stacked and hydrogen-bonded dimers, as well as vertical columns and planar ribbons, respectively, obtained by periodically replicating the dimers. Our results are in good agreement with experimental data for isolated molecules, isolated dimers, and periodic ribbons. For stacked dimers and columns, the stability is affected by the relative charge distribution of the pi orbitals in adjacent guanine molecules. pi-pi coupling in some stacked columns induces dispersive energy bands, while no dispersion is identified in the planar ribbons along the connections of hydrogen bonds. The implications for different materials comprised of guanine aggregates are discussed. The bandstructure of dispersive configurations may justify a contribution of band transport (Bloch type) in the conduction mechanism of deoxyguanosine fibres, while in DNA-like configurations band transport should be negligible.Comment: 21 pages, 6 figures, 3 tables, to be published in Phys. Rev.

Verification for Everyone? An Overview of Dynamic Logic

This note, reporting the homonym keynote presented in the International Symposium on Molecular Logic and Computational Synthetic Biology 2018, traces an informal roadmap on Dynamic Logic (DL) field, focusing on its versatility and resilience to be adjusted and adopted in a wide class of application domains and computational paradigms. The exposition argues the room for developments on tagging DL to the analysis of synthetic biologic domain.publishe

Composition Dependence of the Structure and Electronic Properties of Liquid Ga-Se Alloys Studied by Ab Initio Molecular Dynamics Simulation

Ab initio molecular dynamics simulation is used to study the structure and electronic properties of the liquid Ga-Se system at the three compositions Ga$_2$Se, GaSe and Ga$_2$Se$_3$, and of the GaSe and Ga$_2$Se$_3$ crystals. The calculated equilibrium structure of GaSe crystal agrees well with available experimental data. The neutron-weighted liquid structure factors calculated from the simulations are in reasonable agreement with recent neutron diffraction measurements. Simulation results for the partial radial distribution functions show that the liquid structure is closely related to that of the crystals. A close similarity between solid and liquid is also found for the electronic density of states and charge density. The calculated electronic conductivity decreases strongly with increasing Se content, in accord with experimental measurements.Comment: REVTeX, 8 pages and 12 uuencoded PostScript figures, submitted to Phys. Rev. B. corresponding author: [email protected]

Stationary Black Holes: Uniqueness and Beyond

The spectrum of known black-hole solutions to the stationary Einstein equations has been steadily increasing, sometimes in unexpected ways. In particular, it has turned out that not all black-hole-equilibrium configurations are characterized by their mass, angular momentum and global charges. Moreover, the high degree of symmetry displayed by vacuum and electro-vacuum black-hole spacetimes ceases to exist in self-gravitating non-linear field theories. This text aims to review some developments in the subject and to discuss them in light of the uniqueness theorem for the Einstein-Maxwell system.Comment: Major update of the original version by Markus Heusler from 1998. Piotr T. Chru\'sciel and Jo\~ao Lopes Costa succeeded to this review's authorship. Significantly restructured and updated all sections; changes are too numerous to be usefully described here. The number of references increased from 186 to 32

The global burden of childhood and adolescent cancer in 2017: an analysis of the Global Burden of Disease Study 2017

© 2019 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license Background: Accurate childhood cancer burden data are crucial for resource planning and health policy prioritisation. Model-based estimates are necessary because cancer surveillance data are scarce or non-existent in many countries. Although global incidence and mortality estimates are available, there are no previous analyses of the global burden of childhood cancer represented in disability-adjusted life-years (DALYs). Methods: Using the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 methodology, childhood (ages 0–19 years) cancer mortality was estimated by use of vital registration system data, verbal autopsy data, and population-based cancer registry incidence data, which were transformed to mortality estimates through modelled mortality-to-incidence ratios (MIRs). Childhood cancer incidence was estimated using the mortality estimates and corresponding MIRs. Prevalence estimates were calculated by using MIR to model survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated by multiplying age-specific cancer deaths by the difference between the age of death and a reference life expectancy. DALYs were calculated as the sum of YLLs and YLDs. Final point estimates are reported with 95% uncertainty intervals. Findings: Globally, in 2017, there were 11·5 million (95% uncertainty interval 10·6–12·3) DALYs due to childhood cancer, 97·3% (97·3–97·3) of which were attributable to YLLs and 2·7% (2·7–2·7) of which were attributable to YLDs. Childhood cancer was the sixth leading cause of total cancer burden globally and the ninth leading cause of childhood disease burden globally. 82·2% (82·1–82·2) of global childhood cancer DALYs occurred in low, low-middle, or middle Socio-demographic Index locations, whereas 50·3% (50·3–50·3) of adult cancer DALYs occurred in these same locations. Cancers that are uncategorised in the current GBD framework comprised 26·5% (26·5–26·5) of global childhood cancer DALYs. Interpretation: The GBD 2017 results call attention to the substantial burden of childhood cancer globally, which disproportionately affects populations in resource-limited settings. The use of DALY-based estimates is crucial in demonstrating that childhood cancer burden represents an important global cancer and child health concern. Funding: Bill & Melinda Gates Foundation, American Lebanese Syrian Associated Charities (ALSAC), and St. Baldrick's Foundation