In vitro and in vivo ocular biocompatibility of electrospun poly(ɛ-caprolactone) nanofibers.

Biocompatibility is a requirement for the development of nanofibers for ophthalmic applications. In this study, nanofibers were elaborated using poly(ε-caprolactone) via electrospinning. The ocular biocompatibility of this material was investigated. MIO-M1 and ARPE-19 cell cultures were incubated with nanofibers and cellular responses were monitored by viability and morphology. The in vitro biocompatibility revealed that the nanofibers were not cytotoxic to the ocular cells. These cells exposed to the nanofibers proliferated and formed an organized monolayer. ARPE-19 and MIO-M1 cells were capable of expressing GFAP, respectively, demonstrating their functionality. Nanofibers were inserted into the vitreous cavity of the rat's eye for 10days and the in vivo biocompatibility was investigated using Optical Coherence Tomography (OCT), histology and measuring the expression of pro-inflammatory genes (IL-1β, TNF-α, VEGF and iNOS) (real-time PCR). The OCT and the histological analyzes exhibited the preserved architecture of the tissues of the eye. The biomaterial did not elicit an inflammatory reaction and pro-inflammatory cytokines were not expressed by the retinal cells, and the other posterior tissues of the eye. Results from the biocompatibility studies indicated that the nanofibers exhibited a high degree of cellular biocompatibility and short-term intraocular tolerance, indicating that they might be applied as drug carrier for ophthalmic use

A model for the impact of the nanostructure size on its gas sensing properties

The size of a metal oxide nanostructure plays a key role in its performance as a gas sensor.</p

Renormalization approach for quantum-dot structures under strong alternating fields

We develop a renormalization method for calculating the electronic structure of single and double quantum dots under intense ac fields. The nanostructures are emulated by lattice models with a clear continuum limit of the effective-mass and single-particle approximations. The coupling to the ac field is treated non-perturbatively by means of the Floquet Hamiltonian. The renormalization approach allows the study of dressed states of the nanoscopic system with realistic geometries as well arbitrary strong ac fields. We give examples of a single quantum dot, emphasizing the analysis of the effective-mass limit for lattice models, and double-dot structures, where we discuss the limit of the well used two-level approximation.Comment: 6 pages, 7 figure

Radiation-induced oscillatory magnetoresistance as a sensitive probe of the zero-field spin splitting in high mobility GaAs/AlGaAs devices

We suggest an approach for characterizing the zero-field spin splitting of high mobility two-dimensional electron systems, when beats are not readily observable in the Shubnikov-de Haas effect. The zero-field spin splitting and the effective magnetic field seen in the reference frame of the electron is evaluated from a quantitative study of beats observed in radiation-induced magnetoresistance oscillations.Comment: 4 pages, 4 color figure

Resistência a Septoria lycopersici em espécies de Solanum (Secção Lycopersicon) e em progênies de S. lycopersicum &#215; S. peruvianum

Septoria leaf spot (Septoria lycopersici) is one of the major fungal diseases of tomatoes (Solanum lycopersicum) in tropical and subtropical regions with humid climates and/or in areas cultivated under sprinkler irrigation systems. Sources of resistance have been found in accessions of Solanum (section Lycopersicon) species. However, many of the described sources are not effective under Brazilian conditions. The objective of this work was to evaluate wild and cultivated Solanum (section Lycopersicon) germplasm to S. lycopersici isolates. A collection of 124 accessions was initially evaluated under greenhouse conditions. Ten accessions were highly resistance (HR), whereas 33 were classified as having a resistant (R) response to S. lycopersici isolates. Field evaluation was also conducted with a sub-set of accessions identified as either HR or R in the greenhouse experiment. This field evaluation confirmed greenhouse tests and indicated the presence of some potential sources of rate-reducing resistance. One highly resistant and eight resistant S. habrochaites accessions were identified as being resistant under both conditions, confirming that this wild species is one of the most promising sources of resistance to S. lycopersici. Five new sources with high levels of resistance were found in S. peruvianum accessions (PI-306811, CNPH-1036, LA-1910, LA-1984 and LA-2744). One accession derived from an interspecific cross between S. lycopersicum and S. peruvianum was also found to be highly resistant and might be useful to introgress resistance factors from this wild species into cultivated tomato germplasm. However, additional breeding efforts will be necessary to introgress into the cultivated tomato the resistance factors identified in other S. peruvianum accessions due to the presence of natural crossing barriers between the two species.A mancha-de-septória (Septoria lycopersici) é importante doença fúngica do tomateiro (Solanum lycopersicum) em áreas tropicais e subtropicais com alta umidade ou quando esta hortaliça é cultivada sob irrigação por aspersão. Fontes de resistência têm sido encontradas em germoplasma de Solanum (secção Lycopersicon). No entanto, muitas das fontes descritas não funcionam nas condições brasileiras. Avaliou-se uma coleção de germoplasma de tomate cultivado e selvagem (Solanum secção Lycopersicon) visando identificar novas fontes de elevada resistência. Uma coleção de 124 acessos foi inicialmente avaliada sob condições de casa de vegetação. Somente dez acessos foram classificados como altamente resistentes e 33 foram classificados como resistentes. Um ensaio de campo foi também conduzido com um subconjunto de acessos promissores identificados no primeiro experimento. Foi confirmada a resposta da maioria dos acessos avaliados em casa de vegetação e indicou a presença de fontes de resistência capazes de reduzir a taxa de progresso da doença. Um acesso de S. habrochaites com elevada resistência e oito acessos resistentes foram identificados, confirmando que esta espécie representa uma das mais promissoras fontes de genes de resistência a S. lycopersici. Cinco novas fontes com elevados níveis de resistência foram identificadas em acessos da espécie S. peruvianum (PI-306811, CNPH-1036, LA-1910, LA-1984 e LA-2744). Um acesso, derivado de cruzamento interespecífico entre S. lycopersicum e S. peruvianum também mostrou-se altamente resistente e poderá ser útil na introgressão deste(s) gene(s) em germoplasma de tomateiro cultivado. No entanto, esforços adicionais de melhoramento serão necessários para transferir para o tomateiro cultivado os fatores de resistência identificados em outros acessos de S. peruvianum, uma vez que existem barreiras naturais de cruzamentos entre estas duas espécies

Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope

Nearby clusters and groups of galaxies are potentially bright sources of high-energy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than ~200 GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits exclude large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gamma-ray flux by a factor of ~5 over a smooth-halo assumption. We also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. In this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.Comment: accepted to JCAP, Corresponding authors: T.E. Jeltema and S. Profumo, minor revisions to be consistent with accepted versio

Capim-elefante (Pennisetum purpureum Schum.), sob duas doses de nitrogênio. Consumo e produção de leite

A produção de leite, o consumo voluntário de matéria seca e a taxa de passagem da FDN no trato gastrintestinal em quatro épocas do ano (julho, outubro, janeiro e março), de vacas mestiças, sob pastejo de capim-elefante, submetido a dois níveis de nitrogênio (300 e 700 kg de N/ha•ano), foram estimados. Foi usado pastejo rotativo com três dias de ocupação e 30 de descanso, empregando-se 36 vacas lactantes mestiças Holandês x Zebu, em uma lotação de 6 vacas/ha. A estimativa de consumo e a taxa de passagem foram determinadas em apenas 24 animais. Para a coleta de extrusas, foram usadas duas vacas esôfago-fistuladas. O consumo foi estimado usando-se a relação produção fecal:indigestibilidade dos alimentos. A produção fecal foi estimada usando-se a FDN da extrusa marcada com dicromato de sódio fornecida em dose única. O consumo de MS total não foi influenciado pelas doses de N e por épocas do ano, com valores médios diários de 10,9 e 10,5 kg /MS•vaca para as doses de 300 e 700 kg N/ha•ano, respectivamente. Entretanto, o consumo de MS do capim-elefante foi influenciado por doses de N e épocas, com valores de 6,5 e 5,6 kg/vaca•dia para as doses de N supracitadas, respectivamente. O capim-elefante contribuiu com 26,0% da MS total ingerida, durante a época seca (julho/outubro) e sua contribuição aumentou para 84,0% na época das águas (janeiro/março). A produção diária de leite não foi influenciada por doses de N, com produções médias de 11,6 e 12,3 kg de leite/vaca•dia, para as doses de 300 e 700 kg N/ha•ano, respectivamente.The milk production, the dry matter intake (DMI) and the NDF passage rate in the gastrointestinal tract in four seasons (July, October, January and March), of crossbred cows, under grazing of elephant grass, submitted to two levels of nitrogen (300 and 700 kg N/ha•year) were estimated. The rotation grazing with three days of occupation and 30 days of resting, using 36 crossbred Holstein Zebu milking cows, in a stocking rate of 6 cows/ha, was used. The estimates of the intake and passage rate were determined only in 24 animals. For the extrusa collection, two esophageal fistulated cows were used. The intake was estimated using the fecal output: feed indigestibility ratio. The fecal output was estimated using the NDF of the extrusa marked with sodium dichromium fed in an unique dose. The total dry matter intake was not affected by the N levels and the year seasons, with average values of 10.9 and 10.5 kg DM/cow, for the levels of 300 and 700kg N/ha•year, respectively. However, the DM intake of the elephant grass was affected by N levels and year seasons, with reported values of 6.55 e 5.63 kg/cow•day, for the above described N levels, respectively. The elephant grass contributed with 26% of the total DM intake during the dry season (July/October) and its contribution increased up to 84% in the rainy season (January/March). The milk production was not affected by N levels, with reported average production of 11.6 and 12.3 kg/cow•day, for the levels of 300 and 700 kg N/ha•year, respectively