Photoreceptor loss in age-related macular degeneration

PURPOSE: The authors showed previously that parafoveal rods, but not cones, decrease during the course of adulthood in donor eyes that were screened to exclude the grossly visible macular drusen and pigmentary disturbances typical of age-related macular degeneration (AMD). Because AMD begins in the parafovea, this selective loss of rods actually may be subclinical AMD not yet visible in the fundus. If so, AMD must have a predilection for rods over cones. The authors tested this hypothesis by determining the relative numbers of cones and rods in donor eyes with mid-to late-stage AMD and in age-matched controls. METHODS: Thirteen eyes (from seven donors) with grossly visible macular drusen and pigmentary disturbances were either wholemounted for photoreceptor counts or sectioned through the fovea for histopathology and carbonic anhydrase histochemistry to label red-green cones. Eyes were assigned to AMD or control groups on the basis of histopathology and clinical history. RESULTS: Five nonexudative AMD (NE-AMD) eyes from three donors showed sparing of foveal cones and loss of rods and cones in the parafovea. In two donors, rod loss exceeded cone loss at most parafoveal locations, and in one donor, rod density was normal and cone density was reduced. In eight exudative AMD (EX-AMD) eyes from five donors, photoreceptors surviving along the margins of and overlying disciform scars were largely cones. CONCLUSIONS: Photoreceptors are lost in NE-AMD as well as in the more severe exudative form, consistent with functional and clinical studies. The authors propose that rods die in older eyes without evidence of overt retinal pigment epithelial disease. In persons susceptible to AMD, the retinal pigment epithelium becomes dysfunctional. Secondarily, rod loss continues and cones begin to degenerate. Eventually, only degenerate cones remain; ultimately, all photoreceptors may disappear.     

Impact of osmotic agent on the transport of components using forward osmosis to separate ethanol from aqueous solutions

The separation of low molecular weight organic compounds such as the ethanol from aqueous solutions represents an important area to be investigated and increment the range of applications of forward osmosis. This investigation assesses the effects of using different draw solutes for ethanol separation from dilute aqueous solutions. The influence of glucose, sucrose, sodium chloride, and magnesium chloride was evaluated in terms of total permeate, reverse solute and ethanol fluxes. Inorganic solutes promoted higher total permeate and ethanol fluxes than the organic solutes (2.5 and 1.5 times higher in average, respectively) for the same molar concentration, while presenting only 1.1 times higher reverse solute fluxes. Despite the lower ethanol flux promoted by the organic draw solutes, these osmotic agents promoted higher concentration of ethanol in the total permeate flux, suggesting that they can also be alternatives for specific processes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4499–4507, 2017     

Surface area variations of coal during solvent extraction

Changes in the surface area of a Wyoming sub-bituminous coal with progressive extraction have been investigated. Surface areas were determined from CO₂ adsorption isotherms at 196 K using the BET equation with 0.234 nm² for the molecular cross-sectional area of the CO₂ molecule at 196 K. Surface areas of the extracted coal varied with extraction time, yield and with the nature of the solvent. A maximum surface area of 265 m²/g was obtained from a four-hour treatment using tetralin at 350 °C as the solvent. The raw coal had a surface area of 99 m²/g.     

Impact of Urbanization on the Hydrodynamics of a Water Table in a Floodplain with High Potential for Renaturation

Large river basins influence the development of human populations either by interfering with population growth or by providing a valuable resource that supports population growth. The Paraíba do Sul River catchment (55,400 km²) in southeastern Brazil supplies more than 14-million people with water, and is located in a region of Brazil with the highest Gross National Product (GNP). This catchment contains 77 floodplains (2156 km²) whose waters are highly regulated, and has a medium urbanization index (18.9%). Fifty-two of these floodplains (67.5%) have characteristics that make them suitable for the implementation of management practices that seek renaturation of the floodplain to ensure the sustainability of regional economic development. The floodplain examined in this study is highly managed and has a great potential for renaturation. We examined variations in groundwater level from the control section (lowest cross-section of the floodplain) to the propagation zone for flooding (9.43 km upstream) from January to December of 2013. The elevation of the water table near the structural control point had less seasonal oscillation than a distant area (p = 0.036). There was also a significant difference in the depth of the water table within the interior of the floodplain (urban area: 3.13 m, non-urban area: 0.49 m, p < 0.001). These results demonstrate that water regulation has been compromised in the study area due to the reduced connection between the river channel and floodplain in the urban region. Thus, land use in this floodplain has interfered with water storage capacity and the connectivity between sub-surface flows. These results suggest that this area is suitable for the implementation of techniques that seek renaturation of the floodplain, so that humans can continue to use this water and so that the effects of climatic changes can be mitigated.     

Computational Modeling for Automatic Path Planning Based on Evaluations of the Effects of Impacts of UAVs on the Ground

There are several works that approach the modeling of navigation environments for the automatic planning of paths for Unmanned Aerial Vehicles (UAVs). However these works do not consider the evaluation of risks to the population in case of accidents with UAVs. The present work proposes a grid-based method to construct visibility graphs based on the evaluation of effects of impacts of UAVs on the ground and on a set of geographic information. The metric used for the evaluation is the minimum acceptable period between accidents of this type. The geographic information to be used consists of georeferenced images and digital elevation models of the surfaces of the navigation environments; urban and rural population density information of the cities in these environments; and the polygonal representation of the cities. The visibility graphs constructed by the proposed method allow the UAVs to plan the shortest paths with a decrease of the probability of fatalities due to accidents with impact of UAVs on the ground. Analyses of the results are presented in this work.     

Determination of inorganic trace elements in edible marine fish from Rio de Janeiro State, Brazil

Fish and seafood may represent risk for human health since they can accumulate contaminants from aquatic environment and magnify them up the food chain. The purpose of this study was to analyze and evaluate the levels of aluminum, zinc, iron, manganese, cobalt, copper, arsenics, selenium, cadmium, barium, lead and bismuth in 11 fish species (Salmo salar, Sardinella brasiliensis, Pomatomus saltatrix, Micropogonias furnieri, Cynoscion leiarchus, Caranx crysos, Priacanthus arenatus, Mugil cephalus, Genypterus brasiliensis, Lopholatilus villarii and Pseudopercis numida) captured at Rio de Janeiro State Coast, Brazil. Concentration ranges (mg kg⁻¹ of wet weight) of the selected elements were compared with those reported in other studies. In some cases, comparison of certain elements in the same fish species was difficult due to the lack of data. Aluminum concentration was significantly high in all samples and only M. cephalus, C. leiarchus e C. crysos presented arsenic concentrations below 1 mg kg⁻¹, limit recommended by Brazilian legislation.     

Efficacy of surface hydrophobic agents in reducing water and chloride ion penetration in concrete

Hydrophobic agents are surface protection materials capable of increasing the angle of contact between the water and the concrete surface. For this reason, hydrophobic agents reduce water (in liquid form) penetration in concrete. Therefore, many European construction regulating agencies recommend this treatment in their maintenance policy. Nonetheless, there continues to be a gap in the understanding about which transport mechanisms of the concrete are modified by the hidrophobic agents. The aim of this study was to fill this gap in regards to reinforced concrete structures inserted in a marine environment. To this end, certain tests were used: Two involving permeability mechanism, one determining capillary absorption, and the last, a migration test used to estimate the chloride diffusion coefficient in saturated condition. Results indicated the efficacy of the hydrophobic agents in cases where capillary suction is the mechanism of water penetration (reduced by 2.12 and 7.0 times, depending of the product). However, when the transport mechanism is permeability this product is not advisable. Moreover, it was demonstrated that the chloride diffusion coefficient (in saturated condition) is reduced by the hydrophobic agents, however, the magnitude of this reduction is minor (reduced by 11% and 17%, depending on the product).      

Optimization of C:N ratio and minimal initial carbon source for poly(3‐hydroxybutyrate) production by Bacillus megaterium

BACKGROUND: The aim of this research was the optimization of poly(3‐hydroxybutyrate)—P(3HB)—production in submerged cultures of Bacillus megaterium in a mineral medium using sucrose as carbon source and nitrogen as the limiting substrate. Small‐scale experiments were carried out in shake flasks at 30 °C and 160 rpm in order to evaluate the best initial sucrose concentration and carbon:nitrogen ratio to maximize biomass accumulation and biopolymer production. An objective function in terms of residual sucrose and P(3HB) production was proposed in order to optimize the amount of carbon source used and the production of P(3HB). RESULTS: High production of P(3HB) was obtained, with approximately 70% (CDW) accumulation in cells without nitrogen limitation and strongly correlated with the pH of the culture. Scaling‐up the system to cultures in a bioreactor, with or without pH control, a reduction of P(3HB) accumulation (around 30% CDW) was observed when compared with shaker cultures, suggesting a possible role of oxygen limitation as a stress signaling for P(3HB) synthesis. CONCLUSIONS: Results of our experiments showed that Bacillus megaterium was able to produce P(3HB) at one of the highest production rates so far reported for this bacterium, making this microorganism very interesting for industrial applications. Comparisons of shaker and bench‐scale bioreactor experiments show both the importance of pH and aeration strategies. It is likely that complex aeration strategies linked to cell metabolism will be necessary for further developments using this bacterium. Copyright © 2009 Society of Chemical Industry