Calcareous nannofossil stratigraphy and key biohorizons of ODP Leg 173 sites

Six sites were drilled on the southern Iberia Abyssal Plain during Ocean Drilling Program (ODP) Leg 173. Three holes (1067A, 1068A, and 1069A) recovered Eocene sediments consisting of thinly bedded turbidite deposits with interbedded hemipelagic sediments (Bouma sequence Te) deposited near the calcite compensation depth. The hemipelagic sediments are barren of nannofossils, necessitating the use of the turbidite deposits to erect an Eocene biostratigraphy for these holes. Moderately preserved, diverse assemblages of nannofossils were recovered from silty clays (Bouma sequence Td) and poorly preserved, less diverse assemblages were recovered from sandy/silty clays (Bouma sequence Tc). Hole 1067A has a continuous record of sedimentation (Subzones CP9a-CP14a) and Holes 1068A and 1069A have similar continuous records (Subzones CP9a-CP12a), although all holes contain barren intervals. Holes 1067A, 1068A, 1069A, 900A (ODP Leg 149), and 398D (Deep Sea Drilling Project Leg 47B) display a similar increase in mass accumulation rates in the lowermost middle Eocene. A reliable Eocene biostratigraphy has been erected using nannofossil data from turbidite sequences, allowing for correlation between Iberia Abyssal Plain sites.

(Table 1) Maximal daily erythemally effective UVB radiation and total ozone content at Vernadsky Station, Antarctica

One of the research programs carried out within the Czech-Ukrainian scientific co-operation is the monitoring of global solar and ultraviolet radiation at the Vernadsky Station (formerly the British Faraday Station), Antarctica. Radiation measurements have been made since 2002. Recently, a special attention is devoted to the measurements of the erythemally effective UVB radiation using a broadband Robertson Berger 501 UV-Biometer (Solar Light Co. Inc., USA). This paper brings some results from modelling the daily sums of erythemally effective UVB radiation intensity in relation to the total ozone content (TOC) in atmosphere and surface intensity of the global solar radiation. Differences between the satellite- and ground-based measurements of the TOC at the Vernadsky Station are taken into consideration. The modelled erythemally effective UVB radiation differed slightly depending on the seasons and sources of the TOC. The model relative prediction error for ground- and satellite-based measurements varied between 9.5% and 9.6% in the period of 2002-2003, while it ranged from 7.4% to 8.8% in the period of 2003-2004.

Filmes de nanopartículas de TiO2 e óxido de grafeno para fotocatálise

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2016.

The IUE INES System: Improved data extraction procedures for IUE

We present the extraction and processing of the IUE Low Dispersion spectra within the framework of the ESA “IUE Newly Extracted Spectra” (INES) System. Weak points of SWET, the optimal extraction implementation to produce the NEWSIPS output products (extracted spectra) are discussed, and the procedures implemented in INES to solve these problems are outlined. The more relevant modifications are: 1) the use of a new noise model, 2) a more accurate representation of the spatial profile of the spectrum and 3) a more reliable determination of the background. The INES extraction also includes a correction for the contamination by solar light in long wavelength spectra. Examples showing the improvements obtained in INES with respect to SWET are described. Finally, the linearity and repeatability characteristics of INES data are evaluated and the validity of the errors provided in the extraction is discussed.

Light harvesting in solar cells using natural pigments from red fruits adsorbed to mesoporous TiO2

Nature has developed strategies to present us with a wide variety of colours, from the green of leaves to the bright colours seen in flowers. Anthocyanins are between these natural pigments that are responsible for the great diversity of colours seen in flowers and fruits. Anthocyanins have been used to sensitize titanium dioxide (TiO2) in Dye-Sensitized Solar Cells (DSSCs). DSSCs have become one of the most popular research topic in photovoltaic cells due to their low production costs when compared to other alternatives. DSSCs are inspired in what happens in nature during photosynthesis. A primary charge separation is achieved by means of a photoexcited dye capable of performing the electron injection into the conduction band of a wide band-gap semiconductor, usually TiO2. With this work we aimed to synthesize a novel mesoporous TiO2 structure as the semiconductor in order to increase the dye loading. We used natural occurring dyes such as anthocyanins and their synthetic flavylium relatives, as an alternative to the widely used metal complexes of Ru(II) which are expensive and are environmentally unsafe. This offers not only the chance to use safer dyes for DSSCs, but also to take profit of waste biological products, such as wine and olive oil production residues that are heavily loaded with anthocyanin dyes. We also performed a photodegradation study using TiO2 as the catalyst to degrade dye contaminants, such as those from the wine production waste, by photo-irradiation of the system in the visible region of the light spectrum. We were able to succeed in the synthesis of mesoporous TiO2 both powder and thin film, with a high capacity to load a large amount of dye. We proved the concept of photodegradation using TiO2 as catalyst. And finally, we show that wine production waste is a possible dye source to DSSCs application.

Solar change and climate: an update in the light of the current exceptional solar minimum

Solar outputs during the current solar minimum are setting record low values for the space age. Evidence is here reviewed that this is part of a decline in solar activity from a grand solar maximum and that the Sun has returned to a state that last prevailed in 1924. Recent research into what this means, and does not mean, for climate change is reviewed.

Solar physics: shining a light on solar impacts

Comparing changes in temperature and solar radiation on centennial timescales can help to constrain the Sun’s impact on climate. New findings regarding the minimum activity level of the Sun reveal that comparisons made so far may have been too simplistic.