Transiting exoplanets from the CoRoT space mission XII. CoRoT-12b: a short-period low-density planet transiting a solar analog star

We report the discovery by the CoRoT satellite of a new transiting giant planet in a 2.83 days orbit about a V = 15.5 solar analog star (M(*) = 1.08 +/- 0.08 M(circle dot), R(*) = 1.1 +/- 0.1 R(circle dot), T(eff) = 5675 +/- 80 K). This new planet, CoRoT-12b, has a mass of 0.92 +/- 0.07 M(Jup) and a radius of 1.44 +/- 0.13 R(Jup). Its low density can be explained by standard models for irradiated planets.

Development of a DNA-dosimeter system for monitoring the effects of solar-ultraviolet radiation

Solar radiation sustains and affects all life forms on Earth. In recent years, the increase in environmental levels of solar-UV radiation due to depletion of the stratospheric ozone layer, as a result of anthropogenic emission of destructive chemicals, has highlighted serious issues of social concern. This becomes still more dramatic in tropical and subtropical regions, where the intensity of solar radiation is higher. To better understand the impact of the harmful effects of solar-UV radiation on the DNA molecule, we developed a reliable biological monitoring system based on the exposure of plasmid DNA to artificial UV lamps and sunlight. The determination and quanti. cation of different types of UV photoproducts were performed through the use of specific DNA repair enzymes and antibodies. As expected, a significant number of CPDs and 6-4PPs was observed when the DNA-dosimeter system was exposed to increasing doses of UVB radiation. Moreover, CPDs could also be clearly detected in plasmid DNA when this system was exposed to either UVA or directly to sunlight. Interestingly, although less abundant, 6-4PPs and oxidative DNA damage were also generated after exposure to both UVA and sunlight. These results confirm the genotoxic potential of sunlight, reveal that UVA may also produce CPDs and 6-4PPs directly in naked DNA and demonstrate the applicability of a DNA-dosimeter system for monitoring the biological effects of solar-UV radiation.

Surface Plasmon-Induced Band Gap in the Photocurrent Response of Organic Solar Cells

A 260 nm layer of organic bulk heterojunction blend of the polymer poly(3-hexylthiophene) (P3HT) and the fullerene [6,6]-phenyl C(61)-butyric (PCBM) was spin-coated in between aluminum and gold electrodes, respectively, on top of a laser inscribed azo polymer surface-relief diffraction grating. Angle-dependent surface plasmons (SPs) with a large band gap were observed in the normalized photocurrent by the P3HT-PCBM layer as a function of wavelength. The SP-induced photocurrents were also investigated as a function of the grating depth and spacing.

Making solar fuels by artificial photosynthesis

In order for solar energy to serve as a primary energy source, it must be paired with energy storage on a massive scale. At this scale, solar fuels and energy storage in chemical bonds is the only practical approach. Solar fuels are produced in massive amounts by photosynthesis with the reduction of CO(2) by water to give carbohydrates but efficiencies are low. In photosystem II (PSII), the oxygen-producing site for photosynthesis, light absorption and sensitization trigger a cascade of coupled electron-proton transfer events with time scales ranging from picoseconds to microseconds. Oxidative equivalents are built up at the oxygen evolving complex (OEC) for water oxidation by the Kok cycle. A systematic approach to artificial photo synthesis is available based on a ""modular approach"" in which the separate functions of a final device are studied separately, maximized for rates and stability, and used as modules in constructing integrated devices based on molecular assemblies, nanoscale arrays, self-assembled monolayers, etc. Considerable simplification is available by adopting a ""dyesensitized photoelectrosynthesis cell"" (DSPEC) approach inspired by dye-sensitized solar cells (DSSCs). Water oxidation catalysis is a key feature, and significant progress has been made in developing a single-site solution and surface catalysts based on polypyridyl complexes of Ru. In this series, ligand variations can be used to tune redox potentials and reactivity over a wide range. Water oxidation electrocatalysis has been extended to chromophore-catalyst assemblies for both water oxidation and DSPEC applications.

USE OF SOLAR ENERGY IN THE TREATMENT OF WATER CONTAMINATED WITH PHENOL BY PHOTOCHEMICAL PROCESSES

The solar driven photo-Fenton process for treating water containing phenol as a contaminant has been evaluated by means of pilot-scale experiments with a parabolic trough solar reactor (PTR). The effects of Fe(II) (0.04-1.0 mmol L(-1)), H(2)O(2) (7-270 mmol L(-1)), initial phenol concentration (100 and 500 mg C L(-1)), solar radiation, and operation mode (batch and fed-batch) on the process efficiency were investigated. More than 90% of the dissolved organic carbon (DOC) was removed within 3 hours of irradiation or less, a performance equivalent to that of artificially-irradiated reactors, indicating that solar light can be used either as an effective complementary or as an alternative source of photons for the photo-Fenton degradation process. A non-linear multivariable model based on a neural network was fit to the experimental results of batch-mode experiments in order to evaluate the relative importance of the process variables considered on the DOC removal over the reaction time. This included solar radiation, which is not a controlled variable. The observed behavior of the system in batch-mode was compared with fed-batch experiments carried out under similar conditions. The main contribution of the study consists of the results from experiments under different conditions and the discussion of the system behavior. Both constitute important information for the design and scale-up of solar radiation-based photodegradation processes.

Open-circuit voltages: Theoretical and experimental optimizations of rear passivated silicon solar cells using Fz and Cz wafers

The theoretical and experimental open-circuit voltage optimizations of a simple fabrication process of silicon solar cells n(+)p with rear passivation are presented. The theoretical results were obtained by using an in-house developed program, including the light trapping effect and metal-grid optimization. On the other hand, the experimental steps were monitored by the photoconductive decay technique. The starting materials presented thickness of about 300 pm and resistivities: FZ (0.5 Omega cm), Cz-type 1 (2.5 Omega cm) and Cz-type 2 (3.3 Omega cm). The Gaussian profile emitters were optimized with sheet resistance between 55 Omega/sq and 100 Omega/sq, and approximately 2.0 mu m thickness in accordance to the theoretical results. Excellent implied open-circuit voltages of 670.8 mV, 652.5 mV and 662.6 mV, for FZ, Cz-type 1 and Cz-type 2 silicon wafers, respectively, could be associated to the measured lifetimes that represents solar cell efficiency up to 20% if a low cost anti-reflection coating system, composed by random pyramids and SiO(2) layer, is considered even for typical Cz silicon. (C) 2009 Elsevier Ltd. All rights reserved.

Nonlinear Interactions in a Piezoceramic Bar Transducer Powered by a Vacuum Tube Generated by a Nonideal Source

Interactions between the oscillations of piezoceramic transducer and the mechanism of as excitation-the generator of the electric current of limited power-supply-are analyzed in this paper In practical situations, the dynamics of the forcing function on a vibrating system cannot be considered as given a priori, and it must be taken as a consequence of the dynamics of the whole system. In other words, the forcing source has limited power as that provided by a dc motor for an example, and thus its own dynamics is influenced by that of the vibrating system being forced. This increases the number of degrees of freedom of the problem, and it is called a nonideal problem. In this work, we present certain phenomena as Sommerfeld effect, jump, saturation, and stability, through the influences of the parameters of the governing equations motion. [DOI: 10.1115/1.3007909]

Implication of the visual system in the regulation of activity cycles in the absence of solar light: 2-[I-125]iodomelatonin binding sites and melatonin receptor gene expression in the brains of demersal deep-sea gadiform fish

Relative eye size, gross brain morphology and central localization of 2-[I-125]iodomelatonin binding sites and melatonin receptor gene expression were compared in six gadiform fish living at different depths in the north-east Atlantic Ocean: Phycis blennoides (capture depth range 265-1260 m), Nezumia aequalis (445-1512 m), Coryphaenoides rupestris (706-1932 m), Trachyrincus murrayi (1010-1884 m), Coryphaenoides guentheri (1030 m) and Coryphaenoides (Nematonurus) armatus (2172-4787 m). Amongst these, the eye size range was 0.15-0.35 of head length with a value of 0.19 for C.(N.) armatus, the deepest species. Brain morphology reflected behavioural differences with well-developed olfactory regions in P.blennoides, T.murrayi and C. (N.) armatus and evidence of olfactory deficit in N. aequalis, C. rupestris and C. guentheri. All species had a clearly defined optic tectum with 2-[I-125] iodomelatonin binding and melatonin receptor gene expression localized to specific brain regions in a similar pattern to that found in shallow-water fish. Melatonin receptors were found throughout the visual structures of the brains of all species. Despite living beyond the depth of penetration of solar light these fish have retained central features associated with the coupling of cycles of growth, behaviour and reproduction to the diel light-dark cycle. How this functions in the deep sea remains enigmatic.

The polar ionosphere at Zhongshan Station on May 11, 1999, the day the solar wind almost disappeared

The solar wind almost disappeared on May 11,1999: the solar wind plasma density and' dynamic pressure were less than 1 cm(-3) and 0.1 nPa respectively, while the interplanetary magnetic field was northward. The polar ionospheric data observed by the multi-instruments at Zhongshan Station in Antarctica on such special event day was compared with those of the control day (May 14). It was shown that geomagnetic activity was very quiet on May 11 at Zhongshan. The magnetic pulsation, which usually occurred at about magnetic noon, did not appear. The ionosphere was steady and stratified, and the F-2 layer spread very little. The critical frequency of dayside F-2 layer, f(0)F(2), was larger than that of control day, and the peak of f(0)F(2) appeared 2 hours earlier. The ionospheric drift velocity was less than usual. There were intensive auroral E-s appearing at magnetic noon. All this indicates that the polar ionosphere was extremely quiet and geomagnetic field was much more dipolar on May 11. There were some signatures of auroral substorm before midnight, such as the negative deviation of the geomagnetic H component, accompanied with auroral E-s and weak Pc3 pulsation.

Melanocytic nevi, solar keratoses, and divergent pathways to cutaneous melanoma

Background: Some melanomas form on sun-exposed body sites, whereas others do not. We previously proposed that melanomas at different body sites arise through different pathways that have different associations with melanocytic nevi and solar keratoses. We tested this hypothesis in a case-case comparative study of melanoma patients in Queensland, Australia. Methods: We randomly selected patients from among three prespecified groups reported to the population-based Queensland Cancer Registry: those with superficial spreading or nodular melanomas of the trunk (n = 154, the reference group), those with such melanomas of the head and neck (n = 77, the main comparison group), and those with lentigo maligna melanoma (LMM) (n = 75, the chronic sun-exposed group). Each participant completed a questionnaire, and a research nurse counted melanocytic nevi and solar keratoses. We calculated exposure odds ratios (ORs) and 95% confidence intervals (CIs) to quantify the association between factors of interest and each melanoma group. Results: Patients with head and neck melanomas, compared with patients with melanomas of the trunk, were statistically significantly less likely to have more than 60 nevi (OR = 0.34, 95% CI = 0.15 to 0.79) but were statistically significantly more likely to have more than 20 solar keratoses (OR = 3.61, 95% CI = 1.42 to 9.17) and also tended to have a past history of excised solar skin lesions (OR = 1.87, 95% CI = 0.89 to 3.92). Patients with LMM were also less likely than patients with truncal melanomas to have more than 60 nevi (OR = 0.32, 95% CI = 0.14 to 0.75) and tended toward more solar keratoses (OR = 2.14, 95% CI = 0.88 to 5.16). Conclusions: Prevalences of nevi and solar keratoses differ markedly between patients with head and neck melanomas or LMM and patients with melanomas of the trunk. Cutaneous melanomas may arise through two pathways, one associated with melanocyte proliferation and the other with chronic exposure to sunlight.

Estudo morfofisiológico e anatômico de dois genótipos de cacaueiro (Theobroma cacao L.) submetidos a diferentes condições de radiação solar

A luminosidade desponta como um dos fatores abióticos de maior importância no estabelecimento das plantas, podendo ocasionar alterações a nível fisiológico e anatômico, interferindo diretamente no desenvolvimento das mesmas e consequentemente, sua produtividade. O cacaueiro (Theobroma cacao – Malvaceae) possui grande interesse econômico devido à utilização de suas sementes para produção de manteiga de cacau e chocolate. Neste sentido, o objetivo deste trabalho foi comparar características fisiológicas e anatômicas de dois genótipos de cacaueiro (PH 16 e IPIRANGA 01), submetidos a diferentes condições de radiação solar de modo a inferir a respeito das condições de luminosidade mais favoráveis ao desenvolvimento dos mesmos. Foram realizadas análises de crescimento, teor de pigmentos, trocas gasosas e anatômicas caulinares e foliares. O delineamento experimental foi em Blocos casualizados (DBC), com 4 repetições em arranjo fatorial 2 x 5, constituído de dois genótipos e 5 níveis de luminosidade (0% - pleno sol -, 18%, 30%, 50% e 80% de sombreamento), totalizando 40 parcelas com 10 plantas cada. Os dados obtidos foram submetidos à análise de variância e regressão. Os resultados de crescimento indicam maior adaptação, de ambos os genótipos, em condições de irradiância alta a moderada. O índice de qualidade de Dickson demonstrou maior capacidade de sobrevivência em condições de campo a níveis altos de irradiância para o genótipo PH 16 e a níveis de irradiância moderada para IPIRANGA 01. Os teores de pigmentos fotossintetizantes de IPIRANGA 01 mostram-se mais elevados na condição de 30% de sombreamento, enquanto que, para PH 16 os maiores teores foram observados em 50% de sombreamento. Ambos os genótipos demonstraram altas taxas de A, Ci, E, A/E, A/Gs e A/Ci, sob elevadas irradiâncias, assim como adaptações anatômicas caulinares e foliares a maiores luminosidades, tais como, maior espessamento do limbo foliar, parênquima paliçádico, esponjoso, limbo foliar, epiderme adaxial e densidade estomática, além de maior densidade e frequência de elementos de vaso e espessura do xilema secundário. Os genótipos PH 16 e IPIRANGA 01 apresentaram uma grande plasticidade em relação aos diferentes níveis de irradiância, no entanto, constatou-se que PH 16 apresentou melhor desempenho sob condições de alta irradiância, como as obtidas nos tratamentos a pleno sol e 18% de sombreamento, enquanto que, IPIRANGA 01 mostrou-se mais adaptado sob sombreamento moderado, a 30% de sombra.