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Purpose: The purpose of this study was to compare the efficacy of chitosan (CS)-derivative and its binding to citric-acid with chelators traditionally used in clinical practice. Methods: 50 lower pre-molars were decoronated, standardizing a length of 15 mm, subsequently were instrumented with telescopic technique up to diameter 40.02, irrigated with 5% sodium hypochlorite. The samples were divided according to the treatment of smear layer (SL) (n = 10). Group I: 5% CS-oligosaccharide, Group II: 5% CS-oligosaccharide citrate, Group III: 10% citric acid, Group IV: 17% ethylenediaminetetraacetic-acid (EDTA), and Group V: distilled water. The samples were sectioned longitudinally, sputtered with gold, and observed with scanning electron microscope (SEM) under ×2000 and ×5000 magnifications. Data were analyzed using Kruskall-Wallis test followed by Mann-Whitney U test. Results: In the apical third, CS-oligosaccharide citrate demonstrated better SL removal compared to the other groups (p < 0.05) but not with EDTA (p > 0.05). In the cervical and middle thirds, no differences were found (p > 0.05). Conclusion: CS-oligosaccharide and CS-oligosaccharide citrate demonstrated similar chelating effect to citric acid and EDTA but were not superior. [ABSTRACT FROM AUTHOR]

Hyperspectral unmixing (HU) is an important task for remotely sensed hyperspectral (HS) data exploitation. It comprises the identification of pure spectral signatures (endmembers) and their corresponding fractional abundances in each pixel of the HS data cube. Several methods have been developed for (semi-) supervised and automatic identification of endmembers and abundances. Recently, the statistical dual-depth sparse probabilistic latent semantic analysis (DEpLSA) method has been developed to tackle the HU problem as a latent topic-based approach in which both endmembers and abundances can be simultaneously estimated according to the semantics encapsulated by the latent topic space. However, statistical models usually lead to computationally demanding algorithms and the computational time of the DEpLSA is often too high for practical use, in particular, when the dimensionality of the HS data cube is large. In order to mitigate this limitation, this article resorts to graphical processing units (GPUs) to provide a new parallel version of the DEpLSA, developed using the NVidia compute device unified architecture. Our experimental results, conducted using four well-known HS datasets and two different GPU architectures (GTX 1080 and Tesla P100), show that our parallel versions of the DEpLSA and the traditional pLSA approach can provide accurate HU results fast enough for practical use, accelerating the corresponding serial versions in at least 30x in the GTX 1080 and up to 147x in the Tesla P100 GPU, which are quite significant acceleration factors that increase with the image size, thus allowing for the possibility of the fast processing of massive HS data repositories. [ABSTRACT FROM AUTHOR]

The concern that climate change may increase fire frequency and intensity has recently heightened the interest in the effects of wildfires on ecosystem functioning. Although short-term fire effects on forest soils are well known, less information can be found on the long-term effects of wildfires on soil fertility. Our objective was to study the 17-year effect of wildfires on forest net mineralization rates and extractable inorganic nitrogen (N) and phosphorus (P) concentrations. We hypothesize that (1) burned forest stands should exhibit lower net mineralization rates than unburned ones; (2) these differences would be greatest during the growing season; (3) differences between soil variables might also be observed among plots from different years since the last fire; and (4) due to fire-resistant geochemical processes controlling P availability, this nutrient should recover faster than N. We used a wildfire chronosequence of natural and unmanaged Pinus canariensis forests in La Palma Island (Canary Islands). Soil samples were collected during winter and spring at 22 burned and unburned plots. We found significantly higher values for net N mineralization and extractable N pools in unburned plots. These differences were higher for the winter sampling date than for the spring sampling date. Unlike extractable N and N mineralization rates, extractable P levels of burned plots exhibited a gradual recovery over time after an initial decrease. These results demonstrate that P. canariensis forest soils showed low resilience after wildfires, especially for N, and that this disturbance might induce long-term changes in ecosystem functioning. [ABSTRACT FROM AUTHOR]

We describe herein a useful model for assessing the environmental impact of the breakage of earthen dams used to retain leachate fluids. To create this model, we analyzed three parameters: (1) the characteristics of both the earthen dam and the leachate; (2) the behavior of the leachate cascade resulting from breakage of the dam; and (3) the environmental effect of the resulting pollution. To accomplish this, we first analyzed the failure of earthen dams for leachate according to the Dam Break Inundation Analysis methodology, which provides the characteristics of the leachate cascade or avalanche resulting from the dam breakage. We then used data for different earthen dams for leachates and calculated the volume of leachate that would reach each point the leachate-flow bed downstream of the dam to generate a graph identifying areas at risk from the leachate cascade. As a third step, we calculated the pollutant charge of leachate, and lastly identified and assessed the environmental factors (EFs) within the risk area. Through these steps we formulated an equation for the environmental risk index (ERI EF), which quantifies the potential environmental impact of the rupture of an earthen dam for leachate on the area surrounding such a dam, and which has a value that ranges from 0 to 1. In order to validate this methodology, we applied the ERI EF equation to nine man-made earthen dams for leachates. All nine are considered safe facilities in having had no accidents in the years since their construction. All have ERI EF values below 0.12, indicating that this value can serve as an appropriate guide to the environmental impact of the rupture of earthen dams that retain leachates. [ABSTRACT FROM AUTHOR]