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Accurate and large-scale assessment of volumetric water content (VWC) plays a critical role in mining waste monitoring to mitigate potential geotechnical and environmental risks. In recent years, time-lapse electrical resistivity tomography (TL-ERT) has emerged as a promising monitoring approach that can be used in combination with traditional invasive and point-measurements techniques to estimate VWC in mine tailings. Moreover, the bulk electrical conductivity (EC) imaged using TL-ERT can be converted into VWC in the field using petrophysical relationships calibrated in the laboratory. This study is the first to assess the scale effect on the accuracy of ERT-predicted VWC in tailings. Simultaneous and co-located monitoring of bulk EC and VWC are carried out in tailings at five different scales, in the laboratory and in the field. The hydrogeophysical datasets are used to calibrate a petrophysical model used to predict VWC from TL-ERT data. Overall, the accuracy of ERT-predicted VWC is [Formula: see text], and the petrophysical models determined at sample-scale in the laboratory remain valid at larger scales. Notably, the impact of temperature and pore water EC evolution plays a major role in VWC predictions at the field scale (tenfold reduction of accuracy) and, therefore, must be properly taken into account during the TL-ERT data processing using complementary hydrogeological sensors. Based on these results, we suggest that future studies using TL-ERT to predict VWC in mine tailings could use sample-scale laboratory apparatus similar to the electrical resistivity Tempe cell presented here to calibrate petrophysical models and carefully upscale them to field applications., (© 2023. The Author(s).)

The investigation of spatio-temporal couplings (STCs) of broadband light beams is becoming a key topic for the optimization as well as applications of ultrashort laser systems. This calls for accurate measurements of STCs. Yet, it is only recently that such complete spatio-temporal or spatio-spectral characterization has become possible, and it has so far mostly been implemented at the output of the laser systems, where experiments take place. In this survey, we present for the first time STC measurements at different stages of a collection of high-power ultrashort laser systems, all based on the chirped-pulse amplification (CPA) technique, but with very different output characteristics. This measurement campaign reveals spatio-temporal effects with various sources, and motivates the expanded use of STC characterization throughout CPA laser chains, as well as in a wider range of types of ultrafast laser systems. In this way knowledge will be gained not only about potential defects, but also about the fundamental dynamics and operating regimes of advanced ultrashort laser systems.

The development of a cover for inclined acid-generating areas, such as the external face of dykes and the slope of waste rock piles, is undoubtedly one of the biggest technical reclamation challenges at several mine sites. The LaRonde mine site, owned and operated by Agnico Eagle Mines (Quebec, Canada) is currently engaged to identify an optimal reclamation scenario for the Dyke 1 of its acid-generating tailings storage facilities. One of the promising reclamation options for controlling water infiltration in the acid-generating waste rock on the Dyke 1 is the use of an inclined cover built with available mine waste materials. An instrumented inclined cell with an inclination angle of 18.3 degrees was built on a slope of this dyke to validate if low sulfide tailings and non potentially acid-generating waste rock can be used as cover material to reclaim the Dyke 1. The instrumented inclined cell was monitored for 3 years (2017 to 2019) using volumetric lysimeters, suction sensors, and volumetric water content sensors. The monitoring was done under natural climatic conditions and artificial wetting events. Under natural conditions, less than 1% (5 mm) of incident rainfall percolated in the volumetric lysimeters installed along the slope of the inclined cell. Under controlled conditions associated with artificial wetting events of 6.4 mm/h over a period of 12 h, net percolation values between 1 and 9% (4 to 60 mm) of the sum of incident precipitation were measured. The distance between the top of the cell and the Down Dip Limit (DDL) point was greater than the slope length of the cover under natural conditions and the DDL point moved from the bottom toward the top to reach values between 12 and 20 m from the top of the slope when the wetting events were applied on the cover. These results confirmed the suitability of mining materials as an inclined cover material to control water infiltration in reactive mine waste rocks., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The generation of acid mine drainage (AMD) remains a major environmental challenge for the mining industry. The reclamation of old mine sites with pre-oxidized tailings is particularly challenging because of indirect oxidation reactions which can limit the overall effectiveness of an oxygen barrier to prevent AMD. The goal of this project was to quantitatively compare the effectiveness of different cover systems to reclaim two pre-oxidized acid-generating tailings sites, located in Quebec (Canada). Following laboratory column tests, field measurements and observations, coupled hydrogeological and geochemical numerical simulations were conducted to evaluate the effect of various system characteristics. Cover performance was assessed by simulating the evolution of the degree of (water) saturation, pore water pressures, oxygen fluxes and leachate quality. Several reclamation options, including monolayer covers and two- or three-layer covers with capillary barrier effect(s) were simulated. The simulations indicate that because of reduced cover effectiveness with pre-oxidized tailings, the general design targets developed for non-oxidized tailings may not always be directly applicable to already oxidized tailings. The simulations also illustrate how the behaviour and efficiency of a monolayer cover placed over reactive tailings depend on specific factors, including water table position, initial porewater chemistry, and cover materials' hydrogeological properties and thicknesses. The results indicate that under a given set of conditions, a bilayer cover (with a capillary break above the reactive tailings) would not significantly improve cover performance (compared to a monolayer cover) due to water losses by evaporation. The simulations show, however, that a well-designed three-layer cover with capillary barrier effects (CCBE) would be efficient in reducing the oxygen flux and AMD generation, even in the case of highly pre-oxidized tailings. The outcomes from this investigation highlight some of the advantages of carrying out coupled hydrogeological and geochemical simulations to assess the long-term behaviour of reclaimed mining sites., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The heterogeneity of waste rock piles is due to the wide and variable grain size distribution of waste rock and construction methods leading to complex internal structures. The general objective of this work was to better understand the effect of such heterogeneity on the coupled transfer processes acting within waste rock piles producing Acid Mine Drainage (AMD). For this purpose, parametric numerical simulations were conducted with the TOUGH AMD numerical simulator, considering 1) three random spatial distributions of the same material properties to assess the resulting behavior, 2) four ranges of material properties with the same spatial distribution to evaluate the effect of the degree of heterogeneity, and 3) the effect of compacted layers due to circulation of heavy equipment during construction. Results show that fine-grained (denser with lower permeability) material present near the boundary of a pile can limit air entry. Coarse materials promote preferential flow of gas and water vapor. Fine-grained materials beneath the pile surface favor the internal condensation of water vapor and thus minimize water loss. The initiation of secondary gas convection cells requires a minimal degree of heterogeneity, which is closely related to the range of permeability between the coarse and the finer material ratio (k(coarse)/k(fine)). The presence of coarse grained material in the pile does not necessarily lead to more convection and higher AMD production. The magnitude of convection rather depends on the amount of fine-grained material and its distribution in the pile. Results also show that low-permeability compacted layers strongly limit convection. Results thus support waste rock pile construction methods integrating fine-grained materials or compacted layers to minimize AMD production.

IL-27 regulates immune responses as well as hematopoiesis and bone remodeling, but its cellular sources in the bone remain unknown. In this study, we investigated whether osteoclasts and osteoblasts-the 2 cell types orchestrating bone homeostasis-could be a source of IL-27 and identified stimuli that induce its expression in vitro. We observed that human monocyte-derived osteoclasts expressed a broader range of TLRs than did human primary osteoblasts and that both cell types exhibited a differential induction of IL-27 expression in response to TLR or cytokine stimulation. Whereas several TLR agonists, notably TLR4 and TLR7/8 agonists, induced substantial expression of IL-27 by osteoclasts, stimulation of osteoblasts with agonists of TLR3 and/or TLR4-the 2 TLRs selectively expressed by these cells-resulted in no or low IL-27 expression. In addition, IL-27 increased TLR3 expression in osteoclasts and enhanced poly(I:C)-mediated induction of IL-27 in these cells. IFN-γ, when combined with either IL-1β plus TNF-α, IL-11, or CNTF, induced significant levels of IL-27 in osteoclasts but not in osteoblasts. In the latter cells, the addition of type I IFN, together with proinflammatory cytokines, was necessary to induce substantial levels of IL-27. Immunohistochemical studies of inflamed and remodeling bone tissue, including cases of infectious osteomyelitis and bone metastases, provided evidence that osteoclasts, osteoblasts, and occasionally osteocytes or chondrocytes, could express IL-27 in situ. This autocrine production of IL-27 by TLR- or cytokine-activated bone cells might constitute a negative-feedback mechanism to limit bone erosion and to dampen T cell-mediated immune pathology during bone inflammation., (© Society for Leukocyte Biology.)

We measure the laser-induced damage threshold (LIDT) fluence under single shot at the surface of Sapphire samples prepared following the standards of two methods yielding to different surface finish and used in optical and laser industry. We use AFM microscopy to measure the roughness parameter Ra and power spectral density (PSD) of the sample surface. We show that the quality of surface topography resulting from surface preparation affects the damage threshold of Sapphire crystals exposed to femtosecond, picosecond, and nanosecond laser conditions at visible and near-infrared wavelengths. We observe a higher resistance to laser damage or macroscopic modification when the surface finish presents a smooth and regular topography. We indeed measure a 1.4 to 2 times increase of the LIDT fluence in femtosecond and picosecond regimes and up to 5 times with nanosecond pulses. Using simple damage model and PSD data, we correlate the LIDT reduction of Sapphire samples of lower quality of surface finish with the high-frequency tail component of their PSD distribution corresponding to striations of the width of a fraction of the laser wavelength. This study emphasizes the importance of detailed assessment of surface topography for laser damage evaluation and understanding and for indicating directions of improvement.

Waste rock piles producing acid mine drainage (AMD) are partially saturated systems involving multiphase (gas and liquid) flow and coupled transfer processes. Their internal structure and heterogeneous properties are inherited from their wide-ranging material grain sizes, their modes of deposition, and the underlying topography. This paper aims at assessing the effect of physical heterogeneity and anisotropy of waste rock piles on the physical processes involved in the generation of AMD. Generic waste rock pile conditions were represented with the numerical simulator TOUGH AMD based on those found at the Doyon mine waste rock pile (Canada). Models included four randomly distributed material types (coarse, intermediate, fine and very fine-grained). The term "randomly" as used in this study means that the vertical profile and spatial distribution of materials in waste rock piles (internal structure) defy stratigraphy principles applicable to natural sediments (superposition and continuity). The materials have different permeability and capillary properties, covering the typical range of materials found in waste rock piles. Anisotropy with a larger horizontal than vertical permeability was used to represent the effect of pile construction by benches, while the construction by end-dumping was presumed to induce a higher vertical than horizontal permeability. Results show that infiltrated precipitation preferentially flows in fine-grained materials, which remain almost saturated, whereas gas flows preferentially through the most permeable coarse materials, which have higher volumetric gas saturation. Anisotropy, which depends on pile construction methods, often controls global gas flow paths. Construction by benches favours lateral air entry close to the pile slope, whereas end-dumping leads to air entry from the surface to the interior of the pile by secondary gas convection cells. These results can be useful to construct and rehabilitate waste rock piles to minimize AMD, while controlling gas flow and oxygen supply., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The efficiency of a water cover to limit dissolved oxygen (DO) availability to underlying acid-generating mine tailings can be assessed by calculating the DO flux at the tailings-water interface. Fick's equations, which are generally used to calculate this flux, require knowing the effective DO diffusion coefficient (Dw) and the reaction (consumption) rate coefficient (Kr) of the tailings, or the DO concentration profile. Whereas Dw can be accurately estimated, few studies have measured the parameter Kr for submerged sulphide tailings. The objective of this study was to determine Kr for underwater sulphide tailings in a laboratory experiment. Samples of sulphide mine tailings (an approximately 6 cm layer) were placed in a cell under a water cover (approximately 2 cm) maintained at constant DO concentration. Two tailings were studied: TA1 with high sulphide content (83% pyrite) and TA2 with low sulphide content (2.8% pyrite). DO concentration was measured with a microelectrode at various depths above and below the tailings-water interface at 1 mm intervals. Results indicate that steady-state condition was rapidly attained. As expected, a diffusive boundary layer (DBL) was observed in all cases. An iterative back-calculation process using the numerical code POLLUTEv6 and taking the DBL into account provided the Kr values used to match calculated and experimental concentration profiles. Kr obtained for tailings TA1 and TA2 was about 80 d(-1) and 6.5 d(-1), respectively. For comparison purposes, Kr obtained from cell tests on tailings TA1 was lower than Kr calculated from the sulphate production rate obtained from shake-flask tests. Steady-state DO flux at the water-tailings interface was then calculated with POLLUTEv6 using tailings characteristics Dw and Kr. For the tested conditions, DO flux ranged from 608 to 758 mg O2/m(2)/d for tailings TA1 and from 177 to 221 mg O2/m(2)/d for tailings TA2. The impact of placing a protective layer of inert material over the tailings was also investigated for tailings TA1 (with high sulphide content). A protective layer of only 5 cm reduced the DO flux into the tailings at about 5 mg/m(2)/d, compared to 608 mg O2/m(2)/d without a protective layer, or an approximately 99% reduction in flux., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Interleukin (IL)-27 is a cytokine of the IL-12 family that displays either immunostimulatory or immunosuppressive functions depending on the context. In various murine tumor models including melanoma models, ectopic expression of IL-27 has been shown to play an anti-tumoral role and to favor tumor regression. In this study, we investigated whether IL-27 might play a role in the development of melanoma in humans. We analyzed the in situ expression of IL-27 in melanocytic lesions (n = 82) representative of different stages of tumor progression. IL-27 expression was not observed in nevus (n = 8) nor in in situ melanoma (n = 9), but was detected in 28/46 (61%) cases of invasive cutaneous melanoma, notably in advanced stages (19/23 cases of stages 3 and 4). In most cases, the main source of IL-27 was tumor cells. Of note, when IL-27 was detected in primary cutaneous melanomas, its expression was maintained in metastatic lesions. These in situ data suggested that the immunosuppressive functions of IL-27 may dominate in human melanoma. Consistent with this hypothesis, we found that IL-27 could induce suppressive molecules such as PD-L1, and to a lesser extent IL-10, in melanoma cells, and that the in situ expression of IL-27 in melanoma correlated with those of PD-L1 and IL-10.

Mine tailings coming from the exploitation of sulphide and/or gold deposits can contain significant amounts of arsenic (As), highly soluble in conditions of weathering. Open mine voids backfilling techniques are now widely practiced by modern mining companies to manage the tailings. The most common one is called cemented paste backfill (CPB), and consists of tailings mixed with low amounts of hydraulic binders (3-5%) and a high proportion of water (typically 25%). The CPB is transported through a pipe network, to be placed in the mine openings. CPB provides storage benefits and underground support during mining operations. Moreover, this technique could also enhance contaminant stabilization, by fixing the contaminants in the binder matrix. CPB composites artificially spiked with As were synthesized in laboratory, using two types of hydraulic binders: a Portland cement, and a mix of fly ash and Portland cement. After curing duration of 66 days, the CPB samples were subjected to several leaching tests in various experimental conditions in order to better understand and then predict the As geochemical behaviour within CPBs. The assessment of the As release indicates that this element is better stabilized in Portland cement-based matrices rather than fly ash-based matrices. The As mobility differs in these two matrices, mainly because of the different As-bearing minerals formed during hydration processes. However, the total As depletion does not exceed 5% at the end of the most aggressive leaching test, indicating that As is well immobilized in the two types of CPB., (Copyright © 2011 Elsevier Ltd. All rights reserved.)