Room temperature absorption in laterally biased Quantum Infrared Detectors fabricated by MBE regrowth

In this paper, we show room temperature operation of a quantum well infrared photodetector (QWIP) using lateral conduction through ohmic contacts deposited at both sides of two n-doped quantum wells. To reduce the dark current due to direct conduction in the wells, we apply an electric field between the quantum wells and two pinch-off Schottky gates, in a fashion similar to a field effect device. Since the normal incidence absorption is strongly reduced in intersubband transitions in quantum wells, we first analyze the response of a detector based on quantum dots (QD). This QD device shows photocurrent signal up to 150 K when it is processed in conventional vertical detector. However, it is possible to observe room temperature signal when it is processed in a lateral structure. Finally, the room temperature photoresponse of the QWIP is demonstrated, and compared with theory. An excellent agreement between the estimated and measured characteristics of the device is foun

Fatty acid profiles of the main lipid classes of green seaweeds from fish pond aquaculture

The lipid composition of five species of green seaweeds (Chaetomorpha linum, Rhizoclonium riparium, Ulva intestinalis, Ulva lactuca, and Ulva prolifera) grown in fish pond aquaculture systems was studied. In particular, the overall fatty acid (FA) profile and the FA profile of each main lipid class found in these seaweed species were thoroughly analyzed. It was found that every seaweed had a specific FA profile, whose specificities were rendered more obvious with the study of the FA profile per lipid class. However, between U.lactuca and U.intestinalis, there were only minor differences. Nonetheless, it was possible to identify significant differences between the palmitic acid content in the phospholipid (PL) and glycolipid (GL) classes of each seaweed. A clear distinction between the FA profiles of R.riparium and C.linum, which belong to the Cladophorales order, and those of Ulva genus, Ulvales order, was also determined. Moreover, there were also differences among lipid classes, yielding large contrasts between PLs+GLs and triacylglycerols (TAGs) as well as between monoacylglycerols (MAGs) and free fatty acids (FFAs). This study also found evidence supporting the location of particular FAs in specific TAG positions. FA profiles have the potential to be used as a chemotaxonomic tool in green seaweeds, providing a simple method to check authenticity of seaweed used as food.Fundacao para a Ciencia e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Collisional dark matter density profiles around supermassive black holes

We solve the spherically symmetric time dependent relativistic Euler equations on a Schwarzschild background space-time for a perfect fluid, where the perfect fluid models the dark matter and the space-time background is that of a non-rotating supermassive black hole. We consider the fluid obeys an ideal gas equation of state as a simple model of dark matter with pressure. Assuming out of equilibrium initial conditions we search for late-time attractor type of solutions, which we found to show a constant accretion rate for the non-zero pressure case, that is, the pressure itself suffices to produce stationary accretion regimes. We then analyze the resulting density profile of such late-time solutions with the function $A/r^{\kappa}$. For different values of the adiabatic index we find different slopes of the density profile, and we study such profile in two regions: a region one near the black hole, located from the horizon up to 50$M$ and a region two from $\sim 800M$ up to $\sim 1500M$, which for a black hole of $10^{9}M_{\odot}$ corresponds to $\sim 0.1$pc. The profile depends on the adiabatic index or equivalently on the pressure of the fluid and our findings are as follows: in the near region the density profile shows values of $\kappa <1.5$ and in the limit of the pressure-less case $\kappa \rightarrow 1.5$; on the other hand, in region two, the value of $\kappa<0.3$ in all the cases we studied. If these results are to be applied to the dark matter problem, the conclusion is that, in the limit of pressure-less gas the density profile is cuspy only near the black hole and approaches a non-cuspy profile at bigger scales within 1pc. These results show on the one hand that pressure suffices to provide flat density profiles of dark matter and on the other hand show that the presence of a central black hole does not distort the density profile of dark matter at scales of 0.1pc.Comment: 7 pages, 8 eps figures, accepted for publication in MNRA

Modelling of corrosion-induced cover cracking in reinforced concrete by an embedded cohesive crack finite element

Corrosion of a reinforcement bar leads to expansive pressure on the surrounding concrete that provokes internal cracking and, eventually, spalling and delamination. Here, an embedded cohesive crack 2D finite element is applied for simulating the cracking process. In addition, four simplified analytical models are introduced for comparative purposes. Under some assumptions about rust properties, corrosion rate, and particularly, the accommodation of oxide products within the open cracks generated in the process, the proposed FE model is able to estimate time to surface cracking quite accurately. Moreover, emerging cracking patterns are in reasonably good agreement with expectations. As a practical case, a prototype application of the model to an actual bridge deck is reported

Rapid extraction and detection of ellagic acid in plant samples using a selective magnetic molecularly imprinted polymer coupled to a fluorescence method

A remarkable growth was noticed in the development of molecularly imprinted polymers (MIPs), which have used as efficient synthetic antibodies that contain selective cavities to the target molecule. Hereunder, a novel strategy using MIP as a sorbent in solid-phase extraction was coupled to a fluorescence method for ellagic acid (EA) purification and immediate detection. The synthesis of magnetic-MIP (MMIP) using a rapid and green ultrasound technology was assessed by central composite design to determine the optimal polymerization conditions for a high-imprinting polymer. The MMIP was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning/transmission electron microscopy, which accurately confirmed the functional, magnetic, and morphological features of MMIP. The prepared MMIP was demonstrated to be selective for EA compared to many similar phenols. The spectrofluorometric method showed a linear range from 0.05 to 2 μg·mL−1 of EA, and the limits of detection (LOD) and quantification (LOQ) were 0.005 and 0.02 μg·mL−1, respectively. Besides, the novel proposed smartphone method using the ultraviolet lamp as the excitation source presented a linear range from 0.2 to 4 μg·mL−1, a LOQ of 0.2 μg·mL−1, and a LOD of 0.07 μg.mL−1. The proposed strategy revealed high efficiency in the extraction and detection of EA in grape, redberry, and green tea. Effectively, the calculated recoveries were ranging from 80 to 102% with low values of relative standard deviation ([removed]10 página

Lectura a fondo 2

Contiene artículos de Carlos Guzman Bockler... [et al.]¿Exclusiones renovadas? tierra y migración en el siglo XXI. Visiones perifericas: poder y cotidianidad en las orillas de la Republica. Guatemala: Memoria abierta: el conflicto armado en perspectiva 1954-199

Pathogenicity of two recent Western Mediterranean West Nile virus isolates in a wild bird species indigenous to Southern Europe: the red-legged partridge

West Nile virus (WNV) is an emerging zoonotic pathogen whose geographic spread and incidence in humans, horses and birds has increased significantly in recent years. WNV has long been considered a mild pathogen causing self-limiting outbreaks. This notion has changed as WNV is causing large epidemics with a high impact on human and animal health. This has been particularly noteworthy since its introduction into North America in 1999. There, native bird species have been shown to be highly susceptible to WNV infection and disease with high mortalities. For this reason, the effect of WNV infection in North American bird species has been thoroughly studied by means of experimental inoculations in controlled trials. To a lesser extent, European wild birds have been shown to be affected clinically by WNV infection. Yet experimental studies on European wild bird species are lacking. The red-legged partridge (Alectoris rufa) is a gallinaceous bird indigenous to the Iberian Peninsula, widely distributed in South Western Europe. It plays a key role in the Mediterranean ecosystem and constitutes an economically important game species. As such it is raised intensively in outdoor facilities. In this work, red-legged partridges were experimentally infected with two recent WNV isolates from the Western Mediterranean area: Morocco/2003 and Spain/2007. All inoculated birds became viremic and showed clinical disease, with mortality rates of 70% and 30%, respectively. These results show that Western Mediterranean WNV variants can be pathogenic for some European bird species, such as the red-legged partridge

Effect of the feed procedure on production of biogas from anaerobic digestion of pear residues using a CSTR Digester

The anaerobic digestion for the production of biogas is one of the best alternative management procedures of the fruits and vegetables wastes (FWV) since it simultaneously allows energy recovery and material recycling if the digestate can be used for soil amendment. Nevertheless, the generation of this kind of residues is frequently concentrated in only few weeks per year, imposing a serious economic limitation. Thus, introduction of the FVW into the anaerobic digester of the municipal wastewaster treatment plant (MWTP) is a very interesting approach. The aim of this work was to investigate the digestion of pear residues using the anaerobic sludge obtained from a MWTP digester under mesophilic conditions and to explore the influence of the feed operating conditions using a continuously stirred tank reactor (CSTR) digester. The results indicate that the continuous feed allows the treatment of almost twice as much residue (10.5 vs 6.0 g L–1 d-1). System instabilities are observed at larger OLRs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Influence of alkalinity addition on biomethanization of fruit and vegetable waste and sewage sludge performance. Batch study

Fruit and vegetable wastes (FVW) are generated in large quantities around the world. This kind of residue constitutes a source of nuisance in municipal landfills because of its high biodegradability. Their high moisture and large biodegradable organic matter content facilitates their treatment by biological techniques among which the anaerobic digestion presents increasing attention. This alternative allows the recovery of energy and a solid product that can be used as an amendment for soils. In this work, we study the possibility of management of Fruit and Vegetable Wastes (FVW) through their simultaneous digestion with the primary sludge of Municipal Wastewater Treatment plants. Results indicate that feed to inoculum ratios and the pH control are the main variables determining the methane yields. The results for a ratio of 50% sludge together with 10 g NaHCO3/kg of residue are among the best obtained, with a methane yield of about 90 L per kg of volatile solids, and a methane concentration of 40% (v/v) of the biogas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech