Percolation Conditions Research Articles

Preparation and characterization of aptamer-based sorbent for the selective extraction of zearalenone and its derivatives from human urine.

The aim of this work is the development of a biomimetic strategy involving a molecular recognition mechanism using aptamers immobilized on a solid support for the analysis of the mycotoxin zearalenone (ZEA) and two of its derivatives in human urine: alpha-zearelenol (α-ZEL) and beta-zearelenol (β-ZEL). Three oligonucleotide sequences reported in theliterature as beingspecific to ZEA were thus covalently grafted onto activated sepharose, and a thorough study of the percolation and washing conditions was performed to promote the selective retention of the three targeted compounds. With the optimized extraction procedure, a strong and selective retention was obtained for ZEA and to a lesser extent α-ZEL and β-ZEL, with extraction recoveries of 88±9%, 77±15%, and 45±12% respectively, in standard solutions. Application of this procedure to spiked human urine strongly highlighted the efficiency of the clean-up effect resulting from the use of this selective sorbent. Limits of quantification of the whole analytical procedure including extraction on oligosorbent andLC-MS analysis were 0.18 and 0.24ngmL-1, for ZEA and α-ZEL, respectively, thus demonstrating clearly the potential of the developed method for monitoring human dietary exposure to these compounds.

Geophysical research applied to the evaluation of percolation conditions of an earth dam

Geophysical research applied to the evaluation of percolation conditions of an earth dam

Emergent conformality in high-density matter

This contribution discusses baryon-rich matter in the context of recent astrophysical observations of neutron stars (NSs) and the structure of the equation of state that arises from these observations. We show that, generating an ensemble of equations of state that fulfill multimessenger constraints, the speed of sound and trace anomaly can reach their conformal values at the center of maximally massive NSs. The local peak of the speed of sound appears at values of the energy and particle densities being consistent with deconfinement and percolation conditions of QCD phase transition. Some implications of advocating a pseudo-conformal symmetry in dense matter are presented.

Novel oligonucleotide-based sorbent for the selective extraction of cadmium from serum samples

The objective was to develop a sorbent functionalized with aptamers for the selective extraction of cadmium from biological samples. Two oligonucleotide sequences reported in literature as specific to cadmium were covalently grafted on activated Sepharose, with grafting yields of 45%. Once the supports packed in cartridges, a thorough study of the percolation conditions favoring Cd(II) retention was performed, demonstrating the importance of the nature of this medium. A high selectivity was reached when applying the optimal conditions as a recovery of 85% was obtained using the sorbent functionalized with one of the specific aptamers and only 1% on the control sorbent grafted with a scramble sequence. A high specificity was also obtained as recoveries for most of other ions were lower than 15%. The capacity of this oligosorbent estimated to 180 ng of Cd(II) for 30 mg of support was perfectly adapted to the trace analysis of Cd(II). The extraction procedure was then applied to a serum sample which was first subjected to acid precipitation. The initial concentration of cadmium in the serum was estimated to 1.83 µg/L using standard addition method and an extraction yield of 75 ± 1.6% was measured. Comparison of these results with those obtained without oligoextraction (recovery of 57%) showed a significant reduction of matrix effects in ICP-MS thanks to the use of the oligosorbent, underlining its interest for a more reliable quantification of Cd(II). This result was confirmed by performing the oligoextraction protocol on a certified serum.

Characterization of Soil Fertility at Different Relief Points in a Humid Residual Massif in the State of Ceará

Introduction: The relief acts as a soil formation factor and interferes, even indirectly, in the physical-chemical composition of soils, so that important variations in fertility can occur along a toposequence. In agricultural crops, variations in fertility have a major impact on productivity and production costs, which makes mapping soil fertility important. The aim of this study was to evaluate the fertility of soils under different agricultural crops and different points of relief in a mountainous area located in the municipality of Aratuba-CE. Theoretical reference: Various studies that relate soil types to the landscape show that deeper and more developed soils generally occupy flatter, or top, relief positions, where conditions for water percolation are favored. (ARTUR et al., 2014; SOUZA JUNIOR and DEMATTÊ, 2008). Braga et al. (2015) verified the existence of a correlation between soil fertility and distribution of tree species. Methodology: The design was in a randomized block in a split-plot scheme, with the plots formed by four cultivation areas, namely: banana trees (A1), banana trees and cashew trees (A2); grass (A3); pigeon pea (A4); and a control area (A5), maintained with natural vegetation. The subplots were formed by three relief positions: top, middle and slope. The physical-chemical variables of the soil were analyzed: pH, potassium, magnesium, calcium, phosphorus, aluminum, potential acidity, base sum, base saturation, total CEC, effective CTC, PST and soil density. Results: It was observed that the top areas have greater amounts of nutrients. Studies of this nature can provide indications about the evolution of pedogeomorphological systems in landscapes and enable the planning of the most appropriate and sustainable agricultural exploration. Conclusion: The top area presents nutrients in greater quantities, compared to the middle and slope, which may indicate that, although this region is more susceptible to leaching, this still occurs initially, to the point of not affecting soil fertility in the area. local.

A universal mechanism for the development of self-ordering processes in systems of identical particles

Based on the hypothesis of the existence of wave long-range action and its role in the development of self-ordering processes, expressed by us in previous works, we carried out a methodological analysis of the applicability of wave representations in systems of identical particles. The main attention in the analysis is paid to the practical application of de Broglie waves in systems of interacting particles. For this purpose, Bohr's theory of the hydrogen atom has been revised and inconsistencies that contradict modern ideas have been corrected. Two conclusions are made: wave representations of particles are of a material nature; the de Broglie wavelength should be determined in terms of the relative momentum of the interacting particles . Based on the materiality of wave representations, the features of the long-wave interaction of particles are determined. It is emphasized that in many manifestations this interaction has a resonant character. This interaction is the foundation for the universal mechanism for the development of self-ordering processes in systems of identical particles. The paper presents an algorithm for the emergence and functioning of a universal mechanism. The condition for the emergence is always any withdrawal of the system from the state of isotropic chaos and the formation of an initial subgroup of particles with the same magnitude and direction of momenta. The most common cause leading to the fulfillment of the condition is monoenergization of the spectrum of particles in the system. The causative agent of the mechanism is direct collisions of particles, in which the probability of long-wavelength representations is the highest. The development of the mechanism is limited only by the fulfillment of the percolation condition - overcoming the percolation threshold. The final stage of the mechanism is the formation of a superfluid component - a kind of macroparticle that does not interact with walls and other molecules. A characteristic wave feature of such a macroparticle is its coherence. Several final stages in the development of self-ordering processes for typical special phenomena in systems of identical particles are analyzed.

Reaching percolation and conformal limits in neutron stars

Generating an ensemble of equations of state that fulfill multimessenger constraints, we statistically determine the properties of dense matter found inside neutron stars (NSs). We calculate the speed of sound and trace anomaly and demonstrate that they are driven towards their conformal values at the center of maximally massive NSs. The local peak of the speed of sound is shown to be located at values of the energy and particle densities which are consistent with deconfinement and percolation conditions in QCD matter. We also analyze fluctuations of the net-baryon number density in the context of possible remnants of critical behavior. We find that the global maxima of the variance of these fluctuations emerge at densities beyond those found in the interiors of NSs.

Application of electrical resistivity tomography (ERT) in uranium mining earth dam

Abstract Dams are built to contain water or mining tailings and provide several benefits to society. The safety and stability of these structures are essential since eventual accidents can generate catastrophic damage. The main cause of ruptures is associated with abnormal seepage, which can progress to an internal erosion process. To assess the stability and safety of dams, periodic inspections are carried out, which typically include visual inspections and geotechnical instrumentation. Some geophysical methods have the potential to assist conventional geotechnical instrumentation using non-destructive and rapid acquisition investigations. The present study applied a finite element forward modeling to evaluate the percolation conditions and water stability in an earth dam of a decommissioned uranium mine in Brazil. The dam is the final structure of the contention system of mine water treatment. The electrical resistivity data were acquired using electrical resistivity tomography (ERT) and Schlumberger array. The results were presented from the inversion of data in 3D models. The data were processed by open-source software (modeling and inversion of geophysical data). The results indicate the presence of water in the vertical filter located in the crest area. The different levels of investigation indicated water infiltration in the rock mass of the dam foundation. These results are supported by structural surveys carried out in the area that indicate a fracturing pattern in the rock mass of the mine area. The results of the study were satisfactory for the desired purposes and demonstrate that geophysical methods constitute an important complementary tool for the geotechnical monitoring dams.

Community detection and percolation of information in a geometric setting

AbstractWe make the first steps towards generalising the theory of stochastic block models, in the sparse regime, towards a model where the discrete community structure is replaced by an underlying geometry. We consider a geometric random graph over a homogeneous metric space where the probability of two vertices to be connected is an arbitrary function of the distance. We give sufficient conditions under which the locations can be recovered (up to an isomorphism of the space) in the sparse regime. Moreover, we define a geometric counterpart of the model of flow of information on trees, due to Mossel and Peres, in which one considers a branching random walk on a sphere and the goal is to recover the location of the root based on the locations of leaves. We give some sufficient conditions for percolation and for non-percolation of information in this model.

Conformality and percolation threshold in neutron stars

Speed of sound is given attention in multi-messenger astronomy as it encodes information of the dense matter equation of state. Recently the trace anomaly was proposed as a more informative quantity. In this work, we statistically determine the speed of sound and trace anomaly and show that they are driven to their conformal values at the centers of maximally massive neutron stars. We show that the local peak in the speed of sound can be associated deconfinement along with percolation conditions in QCD matter.

Tropical Weathering History Recorded in the Silicon Isotopes of Lateritic Weathering Profiles

AbstractUnder tropical climates, mineral assemblages composing lateritic weathering profiles offer precious records of past weathering conditions. Silicon (Si) isotope signatures in the clay fractions of a deep lateritic profile in central Amazonia, Brazil, in combination with previously determined kaolinite ages, suggest that the surrounding region underwent two major weathering episodes, distinct in their intensity. The first episode (ca. 35–20 Ma) of moderate intensity produced well‐crystallized kaolinites from the parent sediment with limited Si isotope fractionation. A more recent (8–6 Ma) and shorter phase caused the replacement, from top to bottom of the profile, of the first kaolinite generation by a new population characterized by higher crystallographic disorder and stronger Si isotope fractionation, suggesting weathering under conditions of rapid water percolation. These inferences are supported by results from an isotope‐enabled reactive transport model, and they are consistent with paleoclimatic and paleogeographic evidences recorded over the Amazon Basin.

A study of the stability of information and telecommunication networks under conditions of stochastic percolation of nodes

In-depth studies of the topological properties of information and telecommunication networks contribute to the understanding of their functional capabilities, including stability. The study of the stability of complex networks to failures in operation when their components fail is based on modeling by sequentially removing nodes or edges of the network (percolation). The paper presents a comparative analysis of sequential and stochastic variants of percolation of network nodes and statistical estimates of the complex two-criterion network stability coefficient. During the study, methods for calculating the average path length based on graph theory were used. In the statistical analysis of the network stability, we applied the analysis of variance and pairwise comparisons according to the Tukey criterion, based on the provisions of the theory of mathematical statistics. The simulation is performed using the Barabashi–Albert and Erdős–Rényi random graph models. The difference between the method of stochastic percolation and sequential percolation is shown. The performed statistical analysis proved the influence of the factor changing the structure of networks on their stability due to stochastic percolation. The dynamics of network stability reduction under stochastic percolation for different types of networks is shown. It is revealed that in some cases, for example, in networks with high density, the stochastic percolation method is the most preferable one. The study shows the possible options for assessing the stability of networks without a priori knowledge about the type of connections between nodes and with a priori knowledge about the type of connections between nodes. In the former case, knowing the number of network nodes, one can calculate the limit values of stability, in the same way as if the nodes were deleted accidentally. The latter option can be used to calculate the stability of networks that are subject to random node failures, for example, when diagnosing technical systems.

Permeability Testing of Drill Core from Basement Rocks in the Fault-Hosted Gryphon U Deposit (Eastern Athabasca Basin, Canada): Insights into Fluid–Rock Interactions Related to Deposit Formation and Redistribution

Fluid percolation conditions in fault zones are often inferred in geologic studies, but the porosity and permeability of rocks are rarely tested during mineral exploration drilling. Routine permeability and porosity tests on drill core, with adequate detection limits and accuracy, can provide new insights into present- and paleo-fluid flow processes and deposit formation in sedimentary basins and permeable fault zones (e.g. uranium deposits, sub-sea hydrothermal ore deposits). In this study, geological and hydrogeological observations were combined with results of over a thousand permeability tests at spot-on unconfined drill core, extracted along transects through the Gryphon U deposit and fault zone, using a pressure-decay N2 gas probe with adequate seal to the rock surface. The new seal method allowed a wide range of permeability determinations under field conditions (over 5 × 10–20 to 10–12 m2). The penetrative macropore networks were observed directly from gas discharge patterns on drill core surfaces. For the tested crystalline basement rocks below the Athabasca Basin, we inferred that the matrix permeability and porosity distribution appear to be preserved since the late Paleoproterozoic/Mesoproterozoic, under the cover of a sedimentary basin. The permeability values at the present time, and the patterns of rock alteration and deformation, offer insights to paleo-hydrogeological conditions. The gneissic and pegmatitic host rocks have relatively low permeability at present time, except fractured (discrete flow channels) and/or intensely altered to a more porous rock. The alternating zones of silicification and desilicification appear to pre-date the intense argillic alteration, and it may have been a result of earlier hydrothermal activity. The Gryphon U deposit occurs in elongated narrow “lenses” along several fault strands of a fault zone (below the unconformity surface and within basement rocks). U-ore is a cementing mineral in fault-related fractures and fault rocks, but remnant flow channels in fractures in U-ore are still preserved. The most permeable and porous fault rocks are coarse gouges (~ 40% porosity, ~ 10–15 m2 permeability) with approximately three orders of magnitude higher rock matrix permeability than the gneissic host rocks. Such fault rocks locally contain carbonaceous matter, and similar fault rocks may have been preferentially mineralized by U to form the U ore lenses, but the role of brittle-ductile and ductile fault and shear zone rocks in U mineralization is not yet clear at Gryphon. Our review of U–Pb uraninite ages at Gryphon suggests a protracted faulting and U-mineralization history. In response to numerous episodic events of brittle deformation and hydrothermal alteration, the permeability and porosity of the host rocks and U-ores have evolved, as observed by multiple cross-cutting reaction fronts. We inferred from the test results and the alteration halo at the U deposit, affecting a wide part of the fault zone, that the permeability and porosity increased by the downward ingress of U-rich acidic basinal brine that percolated into the basement-hosted (rooted) shear/fault zone and nearby crystalline basement rocks. However, the younger prominent U roll/redox-fronts caused local-scale reduction in porosity and permeability by hematite cementation.

Mobility of contaminants of emerging concern in soil column experiments

In this study, laboratory column experiments under water saturated conditions were conducted for over 35 days to investigate the transport of nine pharmaceuticals (nadolol, sulfamethizole, sulfamethoxazole, sulfamethoxypyridazine, carbamazepine, ibuprofen, diclofenac, hydrochlorothiazide, and gemfibrozil) and four artificial sweeteners (acesulfame, saccharin, cyclamate, and sucralose) in two soils (S and C) with similar organic carbon content (between 0.8 and 1.1%) and pH (7.90 and 7.25) but different texture (58.3 and 85.5% of silt+clay, respectively). Ibuprofen and artificial sweeteners reached maximum concentrations at the outlet of the columns and showed a homogenous vertical profile in the aqueous phase, with the same concentration in all sampling ports under flow percolation conditions. Regarding carbamazepine and hydrochlorothiazide, apparent retardation was observed for both and was attributed to sorption. Nadolol, a positively charged beta-blocker, did not show any apparent breakthrough. After 35 days, the columns were washed using tap water for over one week. Soils were then analyzed at different depths and vertical concentration profiles were plotted. Overall, highest concentrations were measured in the top most layers for contaminants in the soil column with higher clay content (C), whereas vertical profiles were more uniform in that with lower clay content (S).

Susceptibility Prediction of Groundwater Hardness Using Ensemble Machine Learning Models

Groundwater resources, unlike surface water, are more vulnerable to disturbances and contaminations, as they take a very long time and significant cost to recover. So, predictive modeling and prevention strategies can empower policymakers for efficient groundwater governance through informed decisions and recommendations. Due to the importance of groundwater quality modeling, the hardness susceptibility mapping using machine learning (ML) models has not been explored. For the first time, the current research aimed to predict groundwater hardness susceptibility using the ML models. The performance of two ensemble models of boosted regression trees (BRT) and random forest (RF) is investigated through the arrangement of a comparative study with multivariate discriminant analysis (MDA). According to the hardness values in 135 groundwater quality monitoring wells, the hard and soft water are determined; then, 11 predictor variables including distance from the sea (DFS), land use, elevation, distance from the river (DFR), depth to groundwater (DTGW), pH, precipitation (PCP), evaporation (E), groundwater level (GWL), curvature, and lithology are used for predicting the groundwater hardness susceptibility map. Results indicated that the variables of DFR, DTGW, elevation, and DFS had a higher contribution to the modeling process. So, the high harness areas are mostly related to low elevations, low DTGW, and proximity to river and sea, which facilitate the percolation conditions for minerals containing calcium or magnesium into groundwater.

Performance evaluation of organoclays for the amoxicillin retention in a dynamic context

The hydraulic conductivity of diverse organoclays was determined through percolation experiments and compared to a raw Na-montmorillonite (Na-Mt). The incorporation of surfactants even at low content drastically changes the hydraulic conductivity with a large increase of about two order of magnitude in contrast to that of Na-Mt (10−12 m s−1). Batch kinetics and equilibrium adsorption experiments confirmed the proper affinity of organoclays to a zwitterion antibiotic: the amoxicillin (AMX) which was quickly adsorbed (at a time below 30 min) at large amounts (up to 1.4 × 10−3 mol g−1). However, in percolation conditions, the significant increase of the permeability led to a short interaction time between the organoclays and the pharmaceutical. In contrast to Na-Mt for which it took age to get only one drop of AMX, leachates, resulting of a percolation through organoclays, were collected for a time below 10 min, not enough sufficient to ensure a proper removal of an antibiotic with concentration reduced by 5–80% of the initial solution.

Intra- and intergranular fission gas transport on large irregular hexagonal grain networks by an included phase model

The evolution of intergranular fission gas bubbles, including growth, percolation through the fuel matrix, venting and tunnel collapse is simulated using the Included Phase Model (IPM). The model accounts for the effects of vacancy and fission gas species on bubble growth and morphology, which ultimately lead to tunnel formation, venting of fission gas, and subsequent tunnel collapse. A simplified two-dimension bubble model is implemented on a randomly generated irregular, equiangular hexagonal network of grain boundaries and coupled to an intragranular diffusion model. A set of 28 simulations were conducted on a 20 by 15 grid of hexagons with an open surface at one end to permit venting and ensuing tunnel collapse. Results are post-processed and considered statistically to investigate macroscopic fission gas release parameters and the percolation of the network. The behaviors of individual grains and edges are further investigated as a function of edge length, equivalent grain size, and proximity to the free surface. This analysis revealed discrete growth modes corresponding to the number of bubbles on each edge. These modes emerge because edge lengths vary continuously but only an integer number of bubbles precipitate on them, leading to an unequal number of bubbles per unit length for different grains, and corresponding difference in vacancy potential. This result may improve edge percolation conditions utilized in other models. Limitations resulting from the two-dimensional model and avenues future development of more quantitative models are also discussed.

Emission estimation and fate modelling of three typical pesticides in Dongjiang River basin, China

Pesticides are widely and intensively used in the world for crops protection. High pesticide loadings can potentially pollute the water resource. However, little is known about the usage, environmental emission and fate of pesticides in river basins. Here, we firstly established a pesticide emission estimation method, and investigated the environmental fate of three commonly used pesticides (chlorpyrifos, triazophos, and isoprothiolane) in Dongjiang River basin, southern China using mathematical modelling approach in combination with field monitoring. The distributed hydrological model SWAT (Soil and Water Assessment Tool) was applied to model the emission of the target pesticides from farmland to stream water, and their fate in the basin. A satisfactory model calibration for flow and suspended sediment was obtained based on eight-year observation data of four hydrological monitoring stations in Dongjiang River basin. The differences between the simulation and observation of pesticides were almost within an order of magnitude, including more than 53% differences within 0.5 order of magnitude. In the river basin, 78860 kg of chlorpyrifos, 54990 kg of triazophos and 35320 kg of isoprothiolane were sprayed onto the crops, the estimated annual emissions of the basin come up to 1801 kg, 3779 kg, and 2330 kg under the conditions of rainfall, surface runoff and percolation. After a series of environmental processes including settlement and degradation within the channels, the predicted export masses for chlorpyrifos, triazophos and isoprothiolane were reduced to 266 kg, 1858 kg, 1350 kg, respectively. Successful prediction suggests that the reliable estimation method combing the SWAT modelling can help us understand the source, concentration levels and fate of pesticides in river basin in different scales. Combing the method of emission and fate modelling method we proposed, countries and regions lacking pesticide-application database can facilitate better management of pesticides.

Ore and Chvátal‐type degree conditions for bootstrap percolation from small sets

AbstractBootstrap percolation is a deterministic cellular automaton in which vertices of a graph begin in one of two states, “dormant” or “active.” Given a fixed positive integer , a dormant vertex becomes active if at any stage it has at least active neighbors, and it remains active for the duration of the process. Given an initial set of active vertices , we say that G ‐percolates (from ) if every vertex in becomes active after some number of steps. Let denote the minimum size of a set such that G ‐percolates from . Bootstrap percolation has been studied in a number of settings and has applications to both statistical physics and discrete epidemiology. Here, we are concerned with degree‐based density conditions that ensure . In particular, we give an Ore‐type degree sum result that states that if a graph satisfies , then either or is in one of a small number of classes of exceptional graphs. (Here, is the minimum sum of degrees of two nonadjacent vertices in .) We also give a Chvátal‐type degree condition: If is a graph with degree sequence such that or for all , then or falls into one of several specific exceptional classes of graphs. Both of these results are inspired by, and extend, an Ore‐type result in a paper by Freund et al.

Comprehensive study of the percolation of water from surface runoff with an emphasis on the retention capacity and intensity of precipitation.

Urban hydrology was created in order to improve methods of managing the runoff of precipitation in towns and protect them from flooding while also protecting public health and environment. The essence of a future solution consists in finding an acceptable compromise of an alternative solution for draining rainwater from a territory. The content of this work is a study focused on resolving the percolation of water from surface runoff and the confrontation between a field test, laboratory analysis, and numerical analysis. By confronting and subsequently proposing conditions for percolation, documents will be created for making urban drainage better and more efficient. The reason for the origin of the subject work follows from the insufficient information on infiltration systems in Slovak technical standards and, likewise, the lack of support for the percolation of water from surface runoff. This work points out the approaches, principles, and fundamentals of a proposal for percolation. The aim of the work is distribution of scientific knowledge in the field of research and solutions for the percolation of water from surface runoff, with emphasis placed on the retention capacity of the selected territory and the intensity of precipitation. A geological study (orientational, detailed or supplementary) must always be conducted with any decision on rainwater percolation in a certain locality. Its range is dependent on the difficulty and type of construction. The preliminary study of areal condition should be focused on detailed engineering-geological and hydrological information. After this work, it is concluded that the percolation of rainwater in urban areas with suitable hydrogeological condition is an effective rainwater management technology as well as protection to congestion of sewer systems.