Water diffusion in rough carbon nanotubes

We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nanotubes with different degrees of deformation at 300 K. We found that the number of hydrogen bonds that water forms depends on nanotube topology, leading to enhancement or suppression of water diffusion. The simulation results reveal that more realistic nanotubes should be considered to understand the confined water diffusion behavior, at least for the narrowest nanotubes, when the interaction between water molecules and carbon atoms is relevant.Comment: 17 pages, 8 figure

Diffusion behavior of water confined in deformed carbon nanotubes

We use molecular dynamics simulations to study the diffusion of water inside deformed carbon nanotubes, with different degrees of eccentricity at 300K. We found a water structural transition between tubular-like to single-file for the (7,7) nanotubes associated with a change from a high to low mobility regimes. The water which in the undeformed (9,9) nanotubes is frozen, becomes liquid for the distortion above a certain threshold. These water diffusion enhancement (suppresion) is related to a reduction (increase) in the number of hydrogen bonds. This suggests that the shape of the nanotube is a particularly important ingredient when considering the dynamical and structural properties of confined water.Comment: 16 pages, 9 figure

Indexação de plantas básicas de citros da Embrapa Mandioca e Fruticultura para a presença de viróides.

Os citros são hospedeiros naturais de espécies de viróides: viróide da exocorte dos citros (Citrus exocortis viroid, CEVd), viróide do nanismo do lúpulo (Hop stunt viroid, HSVd), Citrus bark cracking viroid (CBCVd), viróide da folha curvada dos citros (Citrus bent leaf viroid, CBLVd), viróide do nanismo dos citros (Citrus dwarfing viroid, CDVd) e, mais recentemente, também foi descrita a ocorrência do Citrus Viroid V (CVd-V) e Citrus viroid VI (CVd-VI). Somente o CEVd e variantes do HSVd são agentes causais de doenças, exocorte e xiloporose, respectivamente. No Brasil já foram identificados as espécies CEVd, HSVd e o CDVd

Optimization of supply diversity for the self-assembly of simple objects in two and three dimensions

The field of algorithmic self-assembly is concerned with the design and analysis of self-assembly systems from a computational perspective, that is, from the perspective of mathematical problems whose study may give insight into the natural processes through which elementary objects self-assemble into more complex ones. One of the main problems of algorithmic self-assembly is the minimum tile set problem (MTSP), which asks for a collection of types of elementary objects (called tiles) to be found for the self-assembly of an object having a pre-established shape. Such a collection is to be as concise as possible, thus minimizing supply diversity, while satisfying a set of stringent constraints having to do with the termination and other properties of the self-assembly process from its tile types. We present a study of what we think is the first practical approach to MTSP. Our study starts with the introduction of an evolutionary heuristic to tackle MTSP and includes results from extensive experimentation with the heuristic on the self-assembly of simple objects in two and three dimensions. The heuristic we introduce combines classic elements from the field of evolutionary computation with a problem-specific variant of Pareto dominance into a multi-objective approach to MTSP.Comment: Minor typos correcte

Termoterapia e premunizaçâo para o Citrus Tristeza Vírus (CTV) ,como ferramentas à certificação fitossanitaria de citros na Bahia.

A tristeza dos citros causada pelo CTV é considerada uma das doenças mais importantes para citricultura brasileira porque é endêmica em nossas condições. O manejo da doença nos pais é realizado pela utilização de porta-enxertos tolerante e premunização de espécies e variedades intolerantes com estirpes menos severas do vírus

Prevalence of high blood pressure in 122, 053 adolescents: A systematic review and meta-regression

Several studies have reported high prevalence of risk factors for cardiovascular disease in adolescents. To perform: i) systematically review the literature on the prevalence of high blood pressure (HBP) in adolescents; ii) analyze the possible methodological factors associated with HBP; and iii) compare the prevalence between developed and developing countries. We revised 10 electronic databases up to August 11, 2013. Only original articles using international diagnosis of HBP were considered. The pooled prevalence's of HBP were estimated by random effects. Meta-regression analysis was used to identify the sources of heterogeneity across studies. Fifty-five studies met the inclusion criteria and total of 122,053 adolescents included. The pooled-prevalence of HBP was 11.2%, 13% for boys, and 9.6% for girls (P < 0.01). Method of measurement of BP and year in which the survey was conducted were associated with heterogeneity in the estimates of HBP among boys. The data indicate that HBP is higher among boys than girls, and that the method of measurement plays an important role in the overall heterogeneity of HBP value distributions, particularly in boys

Density anomaly in a competing interactions lattice gas model

We study a very simple model of a short-range attraction and an outer shell repulsion as a test system for demixing phase transition and density anomaly. The phase-diagram is obtained by applying mean field analysis and Monte Carlo simulations to a two dimensional lattice gas with nearest-neighbors attraction and next-nearest-neighbors repulsion (the outer shell). Two liquid phases and density anomaly are found. The coexistence line between these two liquid phases meets a critical line between the fluid and the low density liquid at a tricritical point. The line of maximum density emerges in the vicinity of the tricritical point, close to the demixing transition

Taxa de decomposição de adubos verdes e disponibilidade de N influenciando o feijoeiro comum em sistema agroecológico de produção.

Os objetivos deste trabalho foram avaliar a produção de fitomassa, a quantidade de N fornecida por ela e a taxa de decomposição de adubos verdes e seus efeitos na cultura do feijoeiro comum em sistema de produção agroecológica.bitstream/CNPAF-2010/29763/1/comt-175.pd

Low genetic diversity associated with low prevalence of Anaplasma marginale in water buffaloes in Marajó Island, Brazil

The rickettsia Anaplasma marginale is the etiologic agent of bovine anaplasmosis, an important tick-borne disease affecting cattle in tropical and subtropical regions of the world. In endemic regions, the genetic diversity of this pathogen is usually related to the high prevalence of the disease in cattle. The major surface protein 1 alpha (MSP1a) has been used as a marker to characterize the genetic diversity and for geographical identification of A. marginale strains. The present study reports the characterization of A. marginale MSP1a diversity in water buffaloes. Blood samples were collected from 200 water buffaloes on Marajó Island, Brazil where the largest buffalo herd is located in the Western hemisphere. Fifteen buffaloes (7.5%) were positive for A. marginale msp1α by PCR. Four different strains of A. marginale with MSP1a tandem repeat structures (4-63-27), (162-63-27), (78-24-24-25-31) and (τ-10-10-15) were found, being (4-63-27) the most common. MSP1a tandem repeats composition in buffalos and phylogenetic analysis using msp1α gene showed that the A. marginale strains identified in buffaloes are closely related to A. marginale strains from cattle. The results demonstrated low genetic diversity of A. marginale associated with low bacterial prevalence in buffaloes and suggested that buffaloes may be reservoirs of this pathogen for cattle living in the same area. The results also suggested that mechanical transmission and not biological transmission by ticks might be playing the major role for pathogen circulation among water buffaloes in Marajó Island, Brazil.We thank the Coordination for the Improvement of Higher Education Personnel (CAPES) foundation and the National Council for Technological and Scientific Development (CNPq) for their financial support.Peer Reviewe