Search results for "FILTRATION"

Speciation and interactions of plutonium with humic substances and kaolinite in aquifer systems

2007

Abstract The speciation of plutonium (Pu) in contact with humic substances (HS) and kaolinite has been performed in aquifer systems. Mainly the redox behavior, complexation, and sorption of plutonium are discussed here. The redox behavior of Pu(VI) in contact with HS was studied and it was found that Pu(VI) is reduced to Pu(III) and Pu(IV) within a couple of weeks. The complexation constants (log  β LC ) of Pu(III) and Pu(IV) with HS have been determined by means of the ultrafiltration method. Furthermore, the sorption of Pu(III) and Pu(IV) onto kaolinite has been investigated as a function of pH by batch experiments under aerobic and anaerobic conditions.

The Coastal Sulfuric Acid Cave System of Santa Cesarea Terme (Southern Italy)

2017

Santa Cesarea Terme in Salento is the only area in which hypogenic caves have been recognized in the Apulia region. In this spa area, the rising of sulfidic thermal waters that mix with both recent fresh infiltration waters and coastal salt water has formed four active sulfuric acid speleogenesis (SAS) caves. These caves are characterized by the typical set of sulfuric acid meso- and micromorphologies, and also by the presence of both gypsum and native sulfur. In all caves, biofilms are visible in the sulfidic thermal waters and on the cave walls.

The effect of the pore structure and zeta potential of porous polymer monoliths on separation performance in ion-exchange mode.

2007

Most often, in bioseparations involving charged macromolecules, the chromatographic systems have low Reynolds and high Peclet numbers. For such systems, an expression is developed and presented in this work for evaluating the throughput in polymeric monoliths where ion-exchange adsorption occurs, as a function of (i) the pressure drop along the length of the monolith, (ii) the functional form and width of the throughpore-size distribution of the monolith, and (iii) the magnitude of the zeta potential on the surface of the throughpores of the monolith. Gaussian and log-normal throughpore-size distributions whose mean throughpore-size and standard deviation values are based on experimentally …

Early warning thresholds for partially saturated slopes in volcanic ashes

2013

Rainfall-induced landslides in steep soil slopes of volcanic origin are a major threat to human lives and infrastructure. In the context of constructing early warning systems in regions where extensive data on landslide occurrences and associated rainfall are inexistent, physically-based tools offer the possibility to establish thresholds for measurable field quantities. In this paper, a combined finite element infinite slope model is presented to study the transient hydraulic response of volcanic ash slopes to a series of rainfall events and to estimate seasonal safety factors. Furthermore, analytical considerations of partially saturated infinite slopes are made to define capillary stress…

Variable scale effects on hillslope soil erosion during rainfall-runoff processes

2021

Abstract The variation of soil erosion across scales remains a controversial issue. A theoretical framework, coupling the normalized Green-Ampt equation for infiltration, 1D kinematic wave model for overland flow, and WEPP erosion modeling approaches for soil erosion, was used to explain and quantify the direct effect of scale on the soil erosion process. The results show that the relation between interrill erosion and slope length accords with a power-law decreasing trend, while the relation of rill erosion versus slope length shows a power-law increasing trend. Moreover, the power-law scaling of interrill erosion becomes more prominent with an increase of rainfall duration and intensity b…

2017

Abstract. The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection–diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection–diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, wh…

Directionlets: Anisotropic Multidirectional representation with separable filtering

2006

In spite of the success of the standard wavelet transform (WT) in image processing in recent years, the efficiency of its representation is limited by the spatial isotropy of its basis functions built in the horizontal and vertical directions. One-dimensional (1-D) discontinuities in images (edges and contours) that are very important elements in visual perception, intersect too many wavelet basis functions and lead to a nonsparse representation. To efficiently capture these anisotropic geometrical structures characterized by many more than the horizontal and vertical directions, a more complex multidirectional (M-DIR) and anisotropic transform is required. We present a new lattice-based pe…

Relationships between glomerular filtration rate and left ventricular mass in uncomplicated essential hypertension

2007

Relationships between estimates of glomerular filtration rate and ultrasonographically determined renal volume in hypertensive patients.

2010

Determination of Glyphosate and AMPA in Food Samples Using Membrane Extraction Technique for Analytes Preconcentration

2021

The method for determining glyphosate (NPG) and its metabolite AMPA (aminomethyl phosphonic acid) in solid food samples using UAE-SLM-HPLC–PDA technique was developed. Firstly, ultrasonic-assisted solvent extraction (UAE) and protein precipitation step were used for the analyte isolation. Then, the supernatant was evaporated to dryness and redissolved in distilled water (100 mL). The obtained solution was alkalized to pH 11 (with 1 M NaOH) and used directly as donor phase in SLM (supported liquid membrane) extraction. The SLM extraction was performed using 2 M NaCl (5 mL) as an acceptor phase. The flow rate of both phases (donor and acceptor) was set at 0.2 mL/min. The membrane extraction t…