Multi-scaled femtosecond laser structuring of stationary titanium surfaces

The evolution of the topography of titanium surfaces treated with femtosecond laser radiation in stationary conditions as a function of radiation fluence and number of laser pulses is investigated. Depending on the processing parameters, ripples, microcolumns, wavy or smooth surfaces can be obtained. The ripples predominate for fluences near the damage threshold of titanium (0.2+/-0.1) J/cm(2), while microcolumns form during the first 200 pulses for fluences between (0.6+/-0.2) and (1.7+/-0.2) J/cm(2). A wavy topography develops for fluences and number of pulses higher than (1.7+/-0.2) J/cm(2) and 300, respectively. A bimodal surface topography consisting of surface ripples overlapping a microcolumnar topography can be obtained if the surfaces are firstly treated to create microcolumns followed by laser treatment with a lower fluence near the ablation threshold of the material, in order to generate periodic rippl

Habitat amount and ambient temperature dictate patterns of anuran diversity along a subtropical elevational gradient

Aim: Patterns of diversity along elevational gradients are driven by species characteristics but remain poorly understood. Filling this gap is imperative given the deteriorating conservation status of anurans worldwide. Here, we examine frog diversity and species composition along a sharp subtropical elevational gradient and assess the degree to which these are determined by environmental and spatial predictors. Location: An extensive southern Brazilian Atlantic Forest elevational gradient ranging from 300 to 1,800 m above sea level. Methods: We sampled 38 ponds and used structural equation modelling to examine the direct and indirect effects of area, climate, habitat amount, habitat complexity and productivity on frog species richness and abundance. We also applied joint species distribution models to investigate the importance of these predictors on frog species composition using species distribution and co-occurrence along the elevational gradient. Results: We recorded 12,636 individuals of 41 frog species. Frog species richness was highest at intermediate elevations, showing a hump-shaped pattern. Frog abundance was highest at lowlands and decreased towards higher elevations. We found support for only the habitat amount hypothesis in explaining overall species richness. Although temperature had a positive influence on productivity and frog abundance, neither predictors were related to species richness. Species composition diverged markedly between lowland and highland frog assemblages, which was mainly attributed to differences in ambient temperature. Main conclusion: Elevations containing more extensive natural habitat areas retained the most species-rich frog assemblages. The mid-elevational peak is likely attributed to lowland habitat (1,400 masl). The entire elevational gradient is, however, critical in maintaining anuran species diversity as lowland assemblages are distinct from those at mid- to high elevations. Our study also shows that anthropogenic habitat loss has a decisive effect on montane frog diversity, reinforcing the need to effectively protect these areas

Optimization of Microcystis aeruginosa cell disruption to enhance microcystin extraction and purification processes

[Excerpt] Worldwide occurrence of cyanobacterium Microcystis aeruginosa and accumulation of its hepatotoxin microcystin (MC) have been responsible for several incidents, leading the World Health Organization to implement guideline values for this toxin in water thus boosting the demand for MC’s analytical standards. Furthermore, cyanotoxins are also considered promising anticancer/antitumor drugs as well as antifungal, antialgal and insecticide agents. Consequently, the U.S. Environmental Protection Agency has introduced cyanotoxins in its list of substances to be studied as a precursor to regulatory action between 2018 and 2020. [...]info:eu-repo/semantics/publishedVersio

Synthesis and Chemical Functionalization of Pseudo-Homogeneous Catalysts for Biodiesel Production—Oligocat

With the increase in global demand for biodiesel, first generation feedstock has drawn the attention of governmental institutions due to the correlation with large land farming areas. The second and third feedstock generations are greener feedstock sources, nevertheless, they require different catalytic conditions if compared with first generation feedstock. In this work, we present the synthesis and characterization of oligoesters matrices and their functionalization to act as a pseudo-homogeneous acid catalyst for biodiesel production, named Oligocat. The main advantage of Oligocat is given due to its reactional medium interaction. Initially, oligocat is a solid catalyst soluble in the alcoholic phase, acting as a homogeneous catalyst, providing better mass transfer of the catalytic groups to the reaction medium, and as the course of the reaction happens, Oligocat migrates to the glycerol phase, also providing the advantage of easy separation of the biodiesel. Oligocat was synthesized through polymerization of aromatic hydroxy acids, followed by a chemical functionalization applying the sulfonation technique. Characterization of the catalysts was carried out by infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). The synthesized oligomers presented 5357 g·mol(−1) (Mw) and 3909 g·mol(−1) (Mn), with a moderate thermal resistance of approximately 175 °C. By sulfonation reaction, it was possible to obtain a high content of sulphonic groups of nearly 70 mol%, which provided the catalytic activity to the oligomeric matrix. With the mentioned physical–chemical properties, Oligocat is chemically designed to convert second generation feedstock to biodiesel efficiently. Preliminary investigation using Oligocat for biodiesel production resulted in conversion rates higher than 96.5 wt.%

Valorization of toxic cyanobacteria biomass - disruption efficiency assessment and consequent bioproduct availability using different disruption techniques

The worldwide occurrence of hepatotoxic cyanobacterium Microcystis aeruginosa and accumulation of its toxin microcystin-LR, have been responsible for several human deaths and animal intoxication incidents. In recognition to its toxicity, the World Health Organization and several national governments established guideline values for this toxin in water, which gave rise to an increasing demand for microcystin′s analytical standards. These standards might be useful either as laboratory standards to apply in human and environmental risk assessment or as tools for molecular and cell biology studies. However, their availability is still limited due to constraints found in production and purification processes, which inflate the final price to values as high as 28000 €/mg. As an example of the increasing interest observed over the last years, U.S. Environmental Protection Agency has recently announced that cyanotoxins became part of its list of substances to be studied as a precursor to regulatory action between 2018 and 2020. Consequently, the optimization of this cyanobacterium cultivation and toxin purification techniques is needed to decrease the production cost of such high added-value product. In biotechnological industrial scale processes, the costs associated with downstream processing often represent more than 60 % of the overall expenses. The aim of this work is therefore to provide an insight regarding the development of a costeffective process for obtaining high-quality and affordable microcystin-LR by evaluating the efficiency of three different methodologies (microwave, freeze-thaw cycles and bead mill) on the disruption of M. aeruginosa and consequent availability of bioproducts. For that purpose, several parameters including time, power, and temperature were tested. The best conditions determined for each extraction method were the following: i) 1.5 minutes at 800 W (microwave), ii) three 12- hour cycles at -20 ºC (freeze-thaw cycles), and iii) 7 minutes using 20 % (v/v) of glass beads (bead mill). According to cell counting and intracellular organic matter release determining techniques, freeze-thaw cycles have shown to be the best disruption method presenting an overall efficiency around 97 %

Even bigger data: preparing for the LHC/ATLAS upgrade

The Large Hadron Collider’s (LHC) experiments’ data volume is expected to grow one order of magnitude following the machine operation conditions upgrade in 2013-2014. The challenge to the scientific results of our team is: i) how to deal with a 10-fold increase in the data volume that must be processed for each analysis, while ii) supporting the increase in the complexity of the analysis applications, iii) reduce the turnover time of the results and iv) these issues must be addressed with limited additional resources given Europe’s present political and economic panorama. In this paper we take a position in this challenge and on the research directions to be explored. A systematic analysis of the analysis applications is presented to study optimization opportunities of the application and of the underlying running system. Than a new local system architecture is proposed to increase resource usage efficiency and to provide a gradual upgrade route from current systems.FCT grants SFRH/BPD/63495/2009; SFRH/BPD/47928/2008, by the UT Austin | Portugal FCT grant SFRH/BD/47840/2008; FCT project PEst-OE/EEI/UI0752/2011

Ageing effects on the wettability behavior of laser textured silicon

In the present work we investigate the ageing of acid cleaned femtosecond laser textured silicon surfaces. Changes in the surface structure and chemistry were analysed by Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS), in order to explain the variation with time of the water contact angles of the laser textured surfaces. It is shown that highly hydrophobic silicon surfaces are obtained immediately after laser texturing and cleaning with acid solutions (water contact angle >120 degrees). However these surfaces are not stable and ageing leads to a decrease of the water contact angle which reaches a value of 80 degrees. XPS analysis of the surfaces shows that the growth of the native oxide layer is most probably responsible for this behavior. (C) 2010 Elsevier B.V. All rights reserved