The main objective of this work is the improvement of the aerodynamic performance of a Chinook-type axial mining fan. It was achieved by investigating the behavior of several parameters affecting it. These include the effects of both the angle of attack of the blades and the blade / tube clearance on other parameters such as the total pressure, air flow, turbulent intensity (It), turbulent energy (Et) and the turbulent dissipeation (Dt) based on computational fluid dynamics (CFD). This study is part of an ongoing project about enhancing the operating conditions of the axial mining fan. The preliminary results indicate an existence of some intervals of both the angle of attack of the blades and the blades / tube clearance over which the fan’s performance is optimal. A functional angle of attack between 20 and 65° has been taken to avoid any risk of interference between blades during installation and rotation. The study of the current lines distribution showed that a leakage flow was developed around fan’s functional clearance. This is due to the existence of a pressure gradient between the facets of the blades in which the fluid flows from the area of higher pressure into area of lower pressure.KeywordsVentilationParametric CFDAngle of attackBlade-tube clearanceTurbulence
In additive manufacturing (AM) process, zero defect target is essential in industry. Before the component is completed, corrective actions are required to be performed. To this end, the integration and the development of non-destructive techniques and methods are of great interest. In this study, the part to be printed was designed via Solid Works Software and converted to STL file format. Then, the resulting G-Code serves as a setpoint for the 3D printer. An experimental in situ setup was conducted using camera of 5MP resolution related to Raspberry Pi to obtain real-time capture of final layer to be analyzed using the developed embedded algorithm. A bilateral filtering is applied on the captured image. In this work, two segmentation methods were used, namely the threshold method and the edge detection method. Both images are superimposed following a series of conducted convolutions. This process facilitates the comparison of both images pixel by pixel and the detection of difference whether it is an excess or a lack of material. Defect are detected when comparing non defected to defected layer. Result obtained was evaluated and discussed to obtain a conclusion and suggest areas for further research.KeywordsAdditive manufacturingDefectComputer vision
Natural root grafts (anastomoses) are morphological unions formed between roots of different trees. Common root systems allow translocation of water, nutrients and photosynthesis products between grafted trees, affecting their growth and their physiology. As carbohydrates are redistributed among grafted trees, the formation of a common root system could reduce the negative effect of intraspecific competition for light or soil resources within stands. The aim of this study was to investigate the role of root grafting on intraspecific competition and growth of balsam fir Abies balsamea. We studied inter‐tree relationships in three natural balsam fir stands of the boreal forest of Quebec (Canada) that contained an average 36% of grafted trees. At each stand, ring width and basal area of trees were measured using dendrochronology techniques. We used mixed linear models to test the effect of root grafting and intraspecific competition on annual basal area increment of trees. Trees before grafting had higher growth rates than trees once grafted. Thus, root grafting did not improve tree growth. Growth of grafted trees was more negatively affected by intraspecific competition than growth of non‐grafted trees. Thus, grafted trees cannot be considered as better competitors than non‐grafted trees. Under high intraspecific competition, growth of larger grafted trees was less affected than that of smaller trees suggesting that they were able to divert resources at their advantage within a union. Our study demonstrated that grafted trees acted on each other's growth and provides support for the idea that grafted trees respond to competition for resources more as a community rather than as individual trees.
Fly-in fly-out (FIFO) continues to be a fact of life for many men working in the mining industry. The goal of this article is to gain a better understanding of the impacts of FIFO on the overall health of men working in the mining sector and the relationship these men have to seeking help. A qualitative study of 22 men was conducted using a semi-structured interview guide modeled after Torkington et al. Results indicate that men present poor health as a result of workplace-specific performance requirements (long workdays, difficult environmental conditions), being physically far away from their family, and the fact that they do not often seek mental health help. Additional studies with a much larger sample of men are necessary.
The internal structure of oriented strand board (OSB) is made of a large number of voids. This results from the complexity of strand distribution within the panel and impacts panel performance greatly. In this research, X-ray microcomputer tomography was used to investigate the void characteristics of OSB panels with different structures. The results indicated that OSB panels have a porosity profile opposite to that of density. Unidirectionally oriented homogeneous boards showed slightly higher total porosity, a steeper porosity profile, and higher void size than other three-layer boards. Still, there was no significant difference between them. Although the changes in bending properties resulted from changes in core layer strand orientation, the slight difference in internal bond and water absorption rate was caused by the narrower void distribution and a larger void size. Panels containing a mixture of black spruce and aspen strands had a higher porosity, a steeper porosity profile, and a small void size compared to panels with black spruce strands. This resulted in better bending properties, worse internal bonding, and a lower water absorption rate and thickness swelling. Thus, the internal bond, water absorption rate, and thickness swelling of the panels with a mixed spruce-aspen core layer decreased with an increase in core layer proportion. An opposite trend was observed for panels with a black spruce core layer.
1. Major environmental changes affect the health and capacity of ecosystems to sustain Indigenous people's well-being in boreal landscapes. Collaboration between Indigenous communities and researchers could help assessing and mitigating the consequences of environmental changes. 2. We used Driver Pressure State Impact (DPSI) conceptual models to compare the perspectives of Indigenous and scientific communities on environmental changes in boreal landscapes of Quebec, Canada. 3. The Indigenous DPSI model emerged from interviews with local land-use experts from two Indigenous communities. The scientific model was informed by the publication topics of expert researchers. 4. We compared the Indigenous and scientific models and exposed convergences and divergences between perspectives. Forestry was identified as a major driver of change in both models. Most issues related to mining, hydro-power and forest road development were specific to the Indigenous model. Climate change and wildfires were of greater interest in the scientific model. 5. Convergences between the perspectives of Indigenous and scientific communities are conducive to collaborative research. Divergences could be addressed through reciprocal knowledge transfer activities, which would lead to research that better aligns with the concerns and needs of Indigenous communities.
Maintaining floristic diversity in recognized biodiversity hotspots is a priority for ecosystem conservation. However, different taxonomical treatments often lead to over or underestimation of floristic diversity in species-rich groups, in particular in Tropical regions as Mesoamerica where floristic surveys are less detailed. Also, understanding the effects of climate changes on species distribution is an emerging question of conservation biology and ecological studies. Here, we used the species-rich genus Piper (Piperaceae) in Veracruz, as a model system to compare reported and actual species richness and to model their occurrence under a climate change scenario. We compared morphological characters of specimens preserved in three of the main Mexican herbaria and then applied new taxonomical treatments. We also used environmental niche models (ENMs) as implemented in Maxent to detect the effects of climate changes on species with different levels of habitat specificity and with specialized biotic interactions. We found that from a total of 108 Piper species reported in Veracruz, 80 were consistent to the new taxonomical treatments due to synonymy or misidentification. ENMs showed that the main determinants of Piper distribution are linked to temperature and precipitations depending on the species. Therefore, different species are likely to respond differently to climate changes. As expected, species with higher habitat specificity and species exhibiting specialized mutualisms are more likely to experience niche contractions. This study shows the importance of reconsidering species richness and of modelling species distribution including specialized ecological interactions as prerequisite for establishing conservation criteria.
L’enseignement par expérientiels à distance ? Réflexion sur l’impact potentiel de la pandémie de COVID-19 sur le sentiment d’efficacité personnelle des étudiantes en art-thérapie (Experiential Distance Learning? Reflection on the Potential Impact of the COVID-19 Pandemic on the Sense of Self-Efficacy of Art Therapy Students)
RÉSUMÉ Le contexte sanitaire entourant la pandémie de COVID-19 a engendré un bouleversement individuel et social important, affectant du même coup les modalités pédagogiques traditionnelles. La formation en art-thérapie ne fut pas épargnée, notamment à l’Université du Québec en Abitibi-Témiscamingue (UQAT). L’UQAT adopte une approche d’enseignement par expérientiels qui engage les étudiantes dans un processus favorisant l’acquisition optimale des compétences inhérentes à l’exercice éthique de la profession, en leur permettant de prendre la posture d’art-thérapeute, au contact de leurs pairs, tout en intégrant émotionnellement les apprentissages réalisés. Comme le contexte pandémique a forcé un passage rapide à l’enseignement à distance, les autrices ont ainsi voulu mettre en perspective les effets potentiels de l’enseignement virtuel de l’art-thérapie sur le développement du sentiment d’efficacité personnelle des étudiantes en art-thérapie. Pour ce faire, elles fondent leur réflexion sur des résultats de sondages réalisés auprès d’étudiantes et de diplômées dans le cadre de l’évaluation du programme de maitrise en art-thérapie. Comme l’enseignement par expérientiels à distance implique des limites quant à l’expérience émotionnelle et le contact réel avec les pairs, il est justifié de se questionner sur les effets qu’auront ces changements sur le sentiment d’efficacité personnelle des stagiaires.
Purpose of review Transparent wood (TW) has attracted much interest from researchers as an emerging optical load-bearing material because of its advanced characteristics. These advantages mainly include being renewable, existing abundant reserves, low cost, interesting optical properties, outstanding mechanical performance, and low thermal conductivity. This review summarizes the current research activities that center on the development of transparent wood. Recent findings This review first addresses wood structural features and chemical composition. The effects of lignin removal, wood species, and resin types on the properties of transparent wood have been explored by researchers. Moreover, many studies highlight the properties of transparent wood, including optical and thermal properties and mechanical performance. An increasing number of studies have focused on the preparation of functional transparent wood and its commercial application. Summary We summarize transparent wood research processes and perspectives on several issues that need further exploration. Lignin removal is one of the most important factors in the processing of transparent wood. Thus, more efficient and greener methods need to be developed to achieve lignin removal or modification to suit the requirements of high-performance transparent wood. The main research objectives would be new functional properties such as electromagnetic shielding, intelligent photoelectric response, high hardness, and electrical conductivity of transparent wood. Graphical abstract
This paper investigates whether firm-level (idiosyncratic) political risk (PR) affects the relationship between corporate social responsibility (CSR) and firm value using a sample of 16,518 firm-year observations which correspond to 2055 unique firms belonging to the Russell 3000 Index over the sample period 2010-2020. Our main findings are as follows: First, firm-level PR does not affect firm value. Second, CSR is positively related to firm value, which is mainly driven by the social component of CSR. Finally, PR has no effect on the CSR-firm value relationship, regardless of the PR type. Our evidence suggests that firm-level PR is not priced in the financial market and as such it does not affect the CSR-firm value relationship. This is consistent with portfolio theory which suggests that only systematic risk is priced.
Old-growth forests of different ages provide specific structures, habitats and ecosystem services. Methods to distinguish this internal diversity are still rare, especially in boreal forests. This research therefore aims to determine the ability of Airborne Laser Scanning (ALS) technology to identify age-related structural diversity in old-growth boreal forests. The study area was located in primary boreal forests in Quebec (Canada) dominated by black spruce (Picea mariana). This area contained 71.8 km² of early old-growth forests (burned 110 years ago), 17.1 km² of late old-growth forests (protected areas; unburned for at least 250 years) and 370 km² of old-growth forests of unknown age (> 125-years-old). We divided the study area into 1 ha tiles, where we extracted seven ALS indices representing vertical and horizontal forest structure. We trained random forest models using an iterative approach to discriminate between early and late old-growth forests based on ALS indices. Model predictions were applied to the old-growth tiles of unknown age, and to 86 field plots (28 from provincial forest surveys and 58 from a dedicated survey of old-growth forests) to evaluate the predictive capacity of the models. The models very accurately distinguished early and late old-growth forests (error-rate = 4.9%). Old-growth survey plots confirmed model ability to discriminate early and late old-growth forests, but not provincial survey plots, possibly because of a lower reliability of these data when forest age exceeds 150 years. Model predictions for tiles of unknown age highlighted the presence of very large tracts of late old-growth forests within a matrix of old-growth forests of intermediate age (≈150–200 years). Overall, ALS-data can contribute to a finer structural age distinction and mapping of boreal old-growth forests. This enhanced knowledge of old-growth landscapes will greatly help to improve their protection, restoration and management. The scarcity of reliable field data for model evaluation is, however, a limitation to be addressed.
This research examined the the desulfurization of tailings from the Amaruq mine at a laboratory scale using froth flotation. Optimization of the flotation process was carried out by testing the conventional potassium amyl-xanthate collector (PAX) and three alternative collectors from the mercaptobenzothiazole (MBT) and dithiophosphate (DTP) families. The main goal was to assess the efficiency of the desulfurization process as a sustainable tailings management approach to prevent contaminated mine drainage generation. Mineralogical characterization of the Amaruq tailings using automated scanning microscopy (QEMSCAN®) revealed that the total sulfide and carbonate contents were about 8 wt% and 3 wt%, respectively; 63.39 % of the sulfur occurred as pyrrhotite, 30.17 % as pyrite, 3.63 % as gersdorffite, and 2.61 % as arsenopyrite. To compare the collector flotation yields, response surface methodology (RSM) was used for statistical design, analysis, and modelling of froth flotation experiments using three key-parameters: pH, activator (CuSO4) dosage, and collector dosage. Four quadratic mathematical models were developed for each collector to calculate sulfide recovery. Variance analysis (ANOVA) revealed that the factors that most affected sulfide recovery were collector type/dosage and pH. Process optimization yielded a maximum sulfide recovery of 96.73 % using 300 g/t PAX and 300 g/t CuSO4 at pH 11. A similar recovery of 95.83 % was achieved using an MBT-MTP based collector under the same conditions. The maximum recovery obtained using MTP and MTP-DTP based collectors while operating at optimal conditions (alkaline pH and maximum collector dosage at 350 g/t) was 88.65 %. The desulfurization process succeeded in decreasing the sulfur content in the tailings to<0.11 wt%. The final tailings were not acid-forming, as confirmed by the acid-base accounting (ABA) and net acid generation (NAG) static tests, compared to the highly acid-forming feed samples. Kinetic testing on the benign desulfurized tailings was also performed to predict and validate their acid generating potential, as well as their contaminant release rates (particularly As, Ni, Cu, Fe, and Zn). The Amaruq desulfurized material did not present any significant risk of contaminated mine drainage generation, and the leached contaminants did not exceed the criteria set by Quebec provincial legislation.
In the mining industry, mineralogical characterization using automated mineralogical devices (scanning electron microscope and reflected optical microscope) has become inescapable, especially for geometallurgical purposes. Mineralogical characterization using these techniques requires correct sampling of the material to obtain representative polished sections. This technical note proposes a method to decide the appropriate number of polished sections which need to be prepared according to the size class considered to achieve enough representability. To illustrate this method, two sampling protocols (at grain form for textural purposes and powder form) of a theoretical typical sulfide ore including a sizing preparation, are presented with the computation method of the variance of the fundamental error related to sampling. The sampling protocols are an adaptation of safety lines derived from the sampling theory of Pierre Gy and need to be adjusted according to the intrinsic properties’ knowledge of the material considered. The method can be very useful to better anticipate the lack of representativity of mineralogical data provided by automated mineralogical devices linked to the sampling preparation.
Introduction Mental health regional differences during pregnancy through the COVID-19 pandemic is understudied. Objectives We aimed to quantify the impact of the COVID-19 pandemic on maternal mental health during pregnancy. Methods A cohort study with a web-based recruitment strategy and electronic data collection was initiated in 06/2020. Although Canadian women, >18 years were primarily targeted, pregnant women worldwide were eligible. The current analysis includes data on women enrolled 06/2020-11/2020. Self-reported data included mental health measures (Edinburgh Perinatal Depression Scale (EPDS), Generalized Anxiety Disorders (GAD-7)), stress. We compared maternal mental health stratifying on country/continents of residence, and identified determinants of mental health using multivariable regression models. Results Of 2,109 pregnant women recruited, 1,932 were from Canada, 48 the United States (US), 73 Europe, 35 Africa, and 21 Asia/Oceania. Mean depressive symptom scores were lower in Canada (EPDS 8.2, SD 5.2) compared to the US (EPDS 10.5, SD 4.8) and Europe (EPDS 10.4, SD 6.5) (p<0.05), regardless of being infected or not. Maternal anxiety, stress, decreased income and access to health care due to the pandemic were increasing maternal depression. The prevalence of severe anxiety was similar across country/continents. Maternal depression, stress, and earlier recruitment during the pandemic (June/July) were associated with increased maternal anxiety. Conclusions In this first international study on the impact of the COVID-19 pandemic, CONCEPTION has shown significant country/continent-specific variations in depressive symptoms during pregnancy, whereas severe anxiety was similar regardless of place of residence. Strategies are needed to reduce COVID-19’s mental health burden in pregnancy. Disclosure No significant relationships.
Sulfide ore processing generates finely ground mine tailings that often contain sulfide minerals such as pyrite, pyrrhotite, arsenopyrite, and gersdorffite. These minerals can generate acid mine drainage or contaminated neutral drainage (CND) due to weathering (aqueous oxidation by oxygen, and bacterial activity). Contaminated neutral mine drainage affects the surrounding environment by contaminant release (e.g., As, Ni, Fe, Cu, and Zn), which is one of the most challenging environmental issues for the mining industry. This paper examines the feasibility of desulfurization by flotation at the laboratory scale as a sustainable tailings management approach to prevent CND generation from tailings produced by the Amaruq mine (Nunavut, Canada). The flotation tests were conducted using a five-level statistical experimental design (DOE) using five parameters that include: collector dosage (PAX), activator dosage (CuSO4), frother dosage (MIBC), pH, and solid content (Cs). The response surface methodology (RSM) was used to predict sulfur recovery and to choose the optimal conditions of flotation. The mineralogical properties of the samples before and after reprocessing were investigated by combining optical microscopy, X-ray diffraction spectroscopy (XRD), and the quantitative evaluation of materials by scanning electron microscopy (QEMSCAN®). The trace element (As, Co, Ni, etc.) microanalysis of the identified minerals was quantified using electron probe micro-analyser (EPMA), and the bulk chemical composition was analyzed using induction furnace, X-ray fluorescence, and ICP-AES/MS. Finally, the geochemical behavior of the initial (WTT) and desulfurized (DWT) tailings was evaluated using kinetic weathering cells. The main results demonstrated that sulfur recovery can reach up to 97 % using the following optimal conditions: pH of 11.5, PAX dosage of 158 g/t, CuSO4 dosage of 300 g/t, MIBC dosage of 55 g/t, and Cs of 29.3 %. Moreover, the residual sulfides within the desulfurized tailings were completely locked within the non-sulfide gangue minerals as analyzed by QEMSCAN® and optical microscopy. Kinetic testing was performed on WTT and DWT to assess their contaminant release rates (especially As, Ni, Cu, Fe, and Zn). The desulfurized material did not cause any significant risk of contaminated mine drainage generation. All released contaminants were below the limits of Quebec provincial legislation.
In the acute phase, burn patients undergo several painful procedures. Pediatric burn care procedures conducted in hydrotherapy have been known to generate severe pain intensity and moderate to high levels of anxiety. Hydrotherapy treatments are done with the use of opioids and benzodiazepines for pain and anxiety. Unfortunately, nonpharmacological methods are rarely combined with pharmacological treatments despite evidence showing that distraction can serve as an effective method for pain management and can potentially decrease analgesic requirements in other painful medical procedures. Virtual reality (VR) is a method that uses distraction to interact within a virtual environment. The use of VR is promising for pain reduction in varying settings. Considering the lack of optimal pain and anxiety management during burn wound care and the positive effect of an immersive distraction for painful procedures, using VR for burn wound care procedures may show promising results. This is a within‐subject randomized controlled trial design in which each participant will serve as his/her own control. A minimum of 20 participants, aged 7 to 17 years old undergoing a burn care session, will receive both standard and experimental treatments during the same session in a randomized order. The experimental treatment will consist of combining VR distraction using the video game Dreamland® to the current standard pharmacological care as per unit protocol. The control group will only receive the unit's standard pharmacological care. The mean difference in both pain intensity scores and in anxiety between the two different sequences will be the primary outcomes of this study. This study evaluates the effect of VR on burn wound care. If results from this study show a positive effect of VR compared to standard care, this protocol may provide guidance on how to implement this type of immersive care as part of the tools available for distraction of painful procedures for acute burn victims.
NOx fire emissions greatly affect atmosphere and human society. The top-down NOx fire emission estimation is highly influenced by satellite fire observation performance (e.g., fire detection) by affecting the derivation of emission coefficient (EC) and fire radiative power (FRP) magnitude. However, such influence is lack of comprehensive study. Here, we developed algorithm to evaluate such impacts in northeastern Asia using multi-source data during 2012–2019. Specifically, we extracted near-concurrent fire observations from MODIS and its successor VIIRS over their orbit-overlapping area and combined respectively with OMI NO2 concentration to derive NOx EC. We compared EC between MODIS and VIIRS, and defined a synergetic effect index (SEI) to explore the combined effects on NOx fire emission estimation due to potentially different ECs and FRP between the two sensors. Finally, we applied EC to estimate NOx emission and made comparison between MODIS and VIIRS. Results show that: 1) both sensors derived considerably higher NOx EC for low-biomass vegetation fires (e.g., grassland fires) than other vegetation fires; however, MODIS EC is about 30% lower than VIIRS EC while similar values are derived for forest fires; 2) synergetic effects induced by different ECs and FRP magnitudes between the two sensors are more significant during fall and winter than in spring and summer; 3) annual NOx emissions based on MODIS EC are 15–23% lower than that from VIIRS EC during 2012–2019, while both are lower than the conventional bottom-up emission inventories GFED and FINN by an average of 23–44%; nevertheless, the EC-based NOx estimations presented high spatiotemporal correlation of R usually between 0.70–0.95 with GFED and FINN. These results reveal and quantify the critical impacts of satellite fire observation performance on EC derivation and fire emission estimation, which is helpful in reducing estimation uncertainty.
Mine waste classification preceding mining, constitutes a proactive solution to classify and segregate mine waste into geo-environmental domains based upon the magnitude of their environmental risks. However, upstream classification requires multi-disciplinary and integrated approaches. This study integrates geological modeling and kinetic modeling to inform upstream mine waste classification based on the pH generated from the main acid-generating and acid-neutralizing reactions once waste rock is stored in oxidizing conditions. Geological models were used to depict the ante-mining spatial distribution of the main reactive minerals: pyrite, albite and calcite. Subsequently, the corresponding block models were created. The dimension of the elementary voxels for each block model was set at 40х40х40 m for this study. The kinetic modeling approach was performed using PHREEQC and VS2DRTI to consider unsaturated conditions. The kinetic modeling simulated a 1D column for each voxel. The column simulates the excavated state of the hosting rock involving kinetic reactions and unsaturated flow under highly oxidizing conditions. Subsequently, the resulting pH for different intervals of time was assigned to its respective voxel. The outcome consists of a spatio-temporal visualization of the pH defining ante-mining geo-environmental domains, thereby providing the opportunity for formulating proactive management measures regarding the hazardous geo-environmental domains.
As soils store more carbon (C) than the Earth’s atmosphere and terrestrial biomass together, the balance between soil C uptake in the form of soil organic matter and release as CO2 upon its decomposition is a critical determinant in the global C cycle regulating our planet’s climate. Although plant litter is the predominant source of C fuelling both soil C build‐up and losses, the issue of how litter chemistry influences this balance remains unresolved. As a contribution to solving that issue, we traced the fate of C during near‐complete decomposition of 13C‐labelled leaf and root litters from 12 plant species in a coarse‐textured soil. We separated the soil organic carbon (SOC) into mineral‐associated organic matter (MAOM) and particulate organic matter (POM) pools, and investigated how 14 litter chemical traits affected novel SOC formation and native SOC mineralization (i.e., the priming effect) in these soil fractions. We observed an overall net increase in SOC due to the addition of litter, which was stronger for root than for leaf litters. The presumed stable MAOM‐C pool underwent both substantial stabilisation and mineralization, whereas the presumably less stable POM‐C pool showed substantial stabilisation and reduced mineralization. Overall, the initial increase in soil C mineralization was fully counterbalanced by a later decrease in native soil C mineralization. POM‐C formation as well as MAOM‐C formation and mineralization were positively related to the initial litter lignin concentration and negatively to that of the nitrogen leachates, whereas the opposite was observed for POM‐C mineralization. Synthesis. Our results highlight the importance of litter chemical traits for SOC formation, and stabilisation, destabilisation, and mineralization. In our coarse‐textured soil, the amount of MAOM‐C did not change despite large C fluxes through this pool. The litter chemical traits that drove these processes differed from those frequently reported for fine‐textured soils far from mineral‐associated C saturation. To account for these discrepancies, we propose an integrative perspective in which litter quality and soil texture interactively control soil C fluxes by modulating several SOC stabilisation and destabilisation mechanisms. Irrespective, our results open new critical perspectives for managing soil C pools globally.
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