Showing papers by "Université de Sherbrooke published in 2022"

A review of filamentous carbon nanomaterial synthesis via catalytic conversion of waste plastic pyrolysis products

Abstract: Waste plastics pose challenging issues to the environment and ecosystems due to their non-biodegradable nature. Aside from mechanical and thermal recycling, thermochemical recycling can convert waste plastics to high-value products. Pyrolysis and gasification processes can convert waste plastics to liquid and gaseous streams that can be used for the synthesis of various products (the waste-refinery concept). Moreover, these same streams can be used to produce filamentous carbon nanomaterials (CNM), that is, carbon nanotubes (CNT) and carbon nanofilaments (CNF). Despite the significant progress made in the field of filamentous CNM synthesis, a full understanding of all aspects of the growth mechanism is still unavailable and, thus, there is no obvious structural control. Consequently, the first section of this article is dedicated to a general summary of CNM, including the current understanding of their growth mechanisms, the difference between the various types, and the conditions which control their growth. The second section aims to synthesize the data published in the scientific literature over the past decade on the production of filamentous CNM from the pyrolysis of waste plastics. The different reactor designs used to convert waste plastics to CNM are considered, and the effects of different parameters, including the catalyst used and process parameters, on the yield and quality of CNM from various types of waste plastics are discussed. Finally, applications for CNM are reviewed.

First-principles study of lead-free double perovskites Ga2PdX6 (X = Cl, Br, and I) for solar cells and renewable energy

Abstract: The double perovskites are promising for solar cells and other optoelectronic applications. In this article, the optoelectronic, transport characteristics of new double perovskites Ga2PdCl6, Ga2PdBr6, and Ga2PdI6 are addressed. The structural and thermodynamic stabilities have been addressed by tolerance factor, and positive frequency of phonon dispersion. The reported band gaps are 2.05 eV, 1.60 eV and 0.80 eV which increases their performance for solar cells. The Ga2PdBr6 is ideal for visible light solar cells with absorption band 400 nm–620 nm. The optical properties analyzed by dielectric constants, polarization, absorption of light, and optical losses. Thermoelectric characteristics has been explained by figure of merit (ZT) in terms of chemical potential, and kelvin temperature. The room temperature ZT (0.77, 0.76, 0.75) for Ga2PdX6 (X = Cl, Br, I) make them potential for thermoelectric applications.

Newly identified climatically and environmentally significant high-latitude dust sources

Abstract: Abstract. Dust particles from high latitudes have a potentially large local, regional, and global significance to climate and the environment as short-lived climate forcers, air pollutants, and nutrient sources. Identifying the locations of local dust sources and their emission, transport, and deposition processes is important for understanding the multiple impacts of high-latitude dust (HLD) on the Earth's systems. Here, we identify, describe, and quantify the source intensity (SI) values, which show the potential of soil surfaces for dust emission scaled to values 0 to 1 concerning globally best productive sources, using the Global Sand and Dust Storms Source Base Map (G-SDS-SBM). This includes 64 HLD sources in our collection for the northern (Alaska, Canada, Denmark, Greenland, Iceland, Svalbard, Sweden, and Russia) and southern (Antarctica and Patagonia) high latitudes. Activity from most of these HLD sources shows seasonal character. It is estimated that high-latitude land areas with higher (SI ≥0.5), very high (SI ≥0.7), and the highest potential (SI ≥0.9) for dust emission cover >1 670 000 km2, >560 000 km2, and >240 000 km2, respectively. In the Arctic HLD region (≥60∘ N), land area with SI ≥0.5 is 5.5 % (1 035 059 km2), area with SI ≥0.7 is 2.3 % (440 804 km2), and area with SI ≥0.9 is 1.1 % (208 701 km2). Minimum SI values in the northern HLD region are about 3 orders of magnitude smaller, indicating that the dust sources of this region greatly depend on weather conditions. Our spatial dust source distribution analysis modeling results showed evidence supporting a northern HLD belt, defined as the area north of 50∘ N, with a “transitional HLD-source area” extending at latitudes 50–58∘ N in Eurasia and 50–55∘ N in Canada and a “cold HLD-source area” including areas north of 60∘ N in Eurasia and north of 58∘ N in Canada, with currently “no dust source” area between the HLD and low-latitude dust (LLD) dust belt, except for British Columbia. Using the global atmospheric transport model SILAM, we estimated that 1.0 % of the global dust emission originated from the high-latitude regions. About 57 % of the dust deposition in snow- and ice-covered Arctic regions was from HLD sources. In the southern HLD region, soil surface conditions are favorable for dust emission during the whole year. Climate change can cause a decrease in the duration of snow cover, retreat of glaciers, and an increase in drought, heatwave intensity, and frequency, leading to the increasing frequency of topsoil conditions favorable for dust emission, which increases the probability of dust storms. Our study provides a step forward to improve the representation of HLD in models and to monitor, quantify, and assess the environmental and climate significance of HLD.

Hygromechanics of softwood cellulosic nanocomposite with intermolecular interactions at fiber-matrix interface investigated with molecular dynamics

Abstract: Intermolecular interactions at the fiber-matrix interface strongly affect the hygromechanical behavior and overall mechanical performance of hydrophilic cellulosic nanocomposites. The mechanics of a model interface consisting of cellulose and galactoglucomannan, inspired by the natural material wood, is investigated by molecular simulations over the full hydration range. With the increment of moisture content, the composite swells anisotropically and non-monotonically with an initial shrinkage. The interphase, a 1–2 nm thick region of matrix strongly influenced by the fiber, shows features of enrichment and ordered structure distinct from bulk. Pulling tests reveal the interfacial shear strength as a function of moisture content. The stick-slip behavior is explained by the strong correlation between the number of hydrogen bonds and the interfacial shear stress, suggesting the force rendered by a single hydrogen bond to be ∼140 pN. These insights shed light on the mechanics of interface and interphase, a topic of less attention yet critical for understanding the mechanical performance of fiber-reinforced composites.

Proteomics Standards Initiative’s ProForma 2.0: Unifying the Encoding of Proteoforms and Peptidoforms

Abstract: It is important for the proteomics community to have a standardized manner to represent all possible variations of a protein or peptide primary sequence, including natural, chemically induced, and artifactual modifications. The Human Proteome Organization Proteomics Standards Initiative in collaboration with several members of the Consortium for Top-Down Proteomics (CTDP) has developed a standard notation called ProForma 2.0, which is a substantial extension of the original ProForma notation developed by the CTDP. ProForma 2.0 aims to unify the representation of proteoforms and peptidoforms. ProForma 2.0 supports use cases needed for bottom-up and middle-/top-down proteomics approaches and allows the encoding of highly modified proteins and peptides using a human- and machine-readable string. ProForma 2.0 can be used to represent protein modifications in a specified or ambiguous location, designated by mass shifts, chemical formulas, or controlled vocabulary terms, including cross-links (natural and chemical) and atomic isotopes. Notational conventions are based on public controlled vocabularies and ontologies. The most up-to-date full specification document and information about software implementations are available at http://psidev.info/proforma.

PixR, a Novel Activator of Conjugative Transfer of IncX4 Resistance Plasmids, Mitigates the Fitness Cost of <i>mcr-1</i> Carriage in Escherichia coli

Abstract: The spread of clinically relevant antibiotic resistance genes is often linked to the dissemination of epidemic plasmids. However, the underlying molecular mechanisms contributing to the successful spread of epidemic plasmids remain unclear.

Electrochemical Aptamer-Based Sensors: A Platform Approach to High-Frequency Molecular Monitoring In Situ in the Living Body.

Abstract: The monitoring of specific molecules in the living body has historically required sample removal (e.g., blood draws, microdialysis) followed by analysis via cumbersome, laboratory-bound processes. Those few exceptions to this rule (e.g., glucose, pyruvate, the monoamines) are monitored using "one-off" technologies reliant on the specific enzymatic or redox reactivity of their targets, and thus not generalizable to the measurement of other targets. In response we have developed in vivo electrochemical aptamer-based (E-AB) sensors, a modular, receptor-based measurement technology that is independent of the chemical reactivity of its targets, and thus has the potential to be generalizable to a wide range of analytes. To further the adoption of this in vivo molecular measurement approach by other researchers and to accelerate its ultimate translation to the clinic, we present here our standard protocols for the fabrication and use of intravenous E-AB sensors.

High-grade ovarian cancer associated H/ACA snoRNAs promote cancer cell proliferation and survival

Abstract: Small nucleolar RNAs (snoRNAs) are an omnipresent class of non-coding RNAs involved in the modification and processing of ribosomal RNA (rRNA). As snoRNAs are required for ribosome production, the increase of which is a hallmark of cancer development, their expression would be expected to increase in proliferating cancer cells. However, assessing the nature and extent of snoRNAs' contribution to cancer biology has been largely limited by difficulties in detecting highly structured RNA. In this study, we used a dedicated midsize non-coding RNA (mncRNA) sensitive sequencing technique to accurately survey the snoRNA abundance in independently verified high-grade serous ovarian carcinoma (HGSC) and serous borderline tumour (SBT) tissues. The results identified SNORA81, SNORA19 and SNORA56 as an H/ACA snoRNA signature capable of discriminating between independent sets of HGSC, SBT and normal tissues. The expression of the signature SNORA81 correlates with the level of ribosomal RNA (rRNA) modification and its knockdown inhibits 28S rRNA pseudouridylation and accumulation leading to reduced cell proliferation and migration. Together our data indicate that specific subsets of H/ACA snoRNAs may promote tumour aggressiveness by inducing rRNA modification and synthesis.

Fluvial Sediments as SCMs: Characterization, Pozzolanic Performance, and Optimization of Equivalent Binder

Abstract: This paper presents an assessment of recycling of thermally treated fluvial sediments as a supplementary cementitious material (SCM). Different calcination treatments were conducted with te...

COVID-19 – an opportunity to improve access to primary care through organizational innovations? A qualitative multiple case study in Quebec and Nova Scotia (Canada)

Abstract: COVID-19 catalyzed a rapid and substantial reorganization of primary care, accelerating the spread of existing strategies and fostering a proliferation of innovations. Access to primary care is an essential component of a healthcare system, particularly during a pandemic. We describe organizational innovations aiming to improve access to primary care and related contextual changes during the first 18 months of the COVID-19 pandemic in two Canadian provinces, Quebec and Nova Scotia.We conducted a multiple case study based on 63 semi-structured interviews (n = 33 in Quebec, n = 30 in Nova Scotia) conducted between October 2020 and May 2021 and 71 documents from both jurisdictions. We recruited a diverse range of provincial and regional stakeholders (e.g., policy-makers, decision-makers, family physicians, nurses) involved in reorganizing primary care during the COVID-19 pandemic using purposeful sampling (e.g., based on role, region). Interviews were transcribed verbatim and thematic analysis was conducted in NVivo12. Emerging results were discussed by team members to identify salient themes and organized into logic models.We identified and analyzed six organizational innovations. Four of these - centralized public online booking systems, centralized access centers for unattached patients, interim primary care clinics for unattached patients, and a community connector to health and social services for older adults - pre-dated COVID-19 but were accelerated by the pandemic context. The remaining two innovations were created to specifically address pandemic-related needs: COVID-19 hotlines and COVID-dedicated primary healthcare clinics. Innovation spread and proliferation was influenced by several factors, such as a strengthened sense of community amongst providers, decreased patient demand at the beginning of the first wave, renewed policy and provider interest in population-wide access (versus attachment of patients only), suspended performance targets (e.g., continuity ≥80%) in Quebec, modality of care delivery, modified fee codes, and greater regional flexibility to implement tailored innovations.COVID-19 accelerated the uptake and creation of organizational innovations to potentially improve access to primary healthcare, removing, at least temporarily, certain longstanding barriers. Many stakeholders believed this reorganization would have positive impacts on access to primary care after the pandemic. Further studies should analyze the effectiveness and sustainability of innovations adapted, developed, and implemented during the COVID-19 pandemic.

Evaluation of biological nitrogen fixation in coarse woody debris from Eastern Canadian boreal forests

Abstract: The contribution of Coarse Woody Debris (CWD) to N inputs in boreal ecosystems has been reported in intensively managed Scandinavian forests in Europe and in Pacific coastal rainforest in North America. These estimates range from 0.085 to 2 kg N ha −1 y −1 . Data from Eastern Canadian forests that receive fewer sylvicultural treatments than do Scandinavian forests and are exposed to a drier climate than the Canadian rainforest are scare. We evaluated contributions of CWD to total BNF in two forest sites dominated by balsam fir and black spruce. We also measured the conversion ratio (R ratio = ARA/N 2 ) for the acetylene reduction assay, which is the method most often used to estimate N 2 -fixation, using parallel 15 N 2 incubations to account for potential methodological biases. We further tested two factors that can affect the R ratio, hance quality of BNF estimates in deadwood; inhibition of N 2 -fixing methanotrophs by acetylene and molybdenum limitation of N 2 -fixation. We report that N 2 -fixation by CWD in balsam fir and black spruce from eastern boreal forest is low (0.05–0.12 kg N ha −1 y −1 ) compared to other estimates for coniferous forests. We also show that moss-covered CWD can significantly contribute to CWD N 2 -fixation and that improper validation of the ARA can lead to significant underestimation of N inputs. • Deadwood contributes to N inputs in Eastern Canadian forests. • Methodological approach used in >50% of studies underestimate N fixation. • Methanotrophic bacteria and covered deadwood contribute to N inputs in boreal forest. • The conversion factor of N-fixers activity into N inputs has to be measured.

Niche differentiation within a cryptic pathogen complex: climatic drivers and hyperparasitism at multiple spatial scales

Abstract: Pathogens are embedded in multi-trophic food webs, which often include co-occurring cryptic species within the same pathogen complex. Nonetheless, we still lack an understanding of what dimensions of the ecological niche might allow these cryptic species to coexist. We explored the role of climate, host characteristics (tree autumn phenology) and attack by the fungal hyperparasite Ampelomyces (a group of fungi attacking plant pathogens) in defining the niches of three powdery mildew species (Erysiphe alphitoides, E. hypophylla and E. quercicola) within a cryptic pathogen complex on the pedunculate oak Quercus robur at the continental (Europe), national (Sweden and France) and landscape scales (a 5 km2 island in southwestern Finland). Previous studies have shown that climate separated the niches of three powdery mildew species (E. alphitoides, E. hypophylla and E. quercicola) in Europe and two species (E. alphitoides and E. quercicola) in France. In our study, we did not detect a significant relationship between temperature or precipitation and the distribution of E. alphitoides and E. hypophylla present in Sweden, while at the landscape scale, temperature, but not relative humidity, negatively affected disease incidence of E. alphitoides in an exceptionally warm year. Tree variation in autumn phenology did not influence disease incidence of powdery mildew species, and hyperparasite presence did not differ among powdery mildew species at the continental, national and landscape scale. Climate did not affect the distribution of the hyperparasite at the continental scale and at the national scale in Sweden. However, climate affected the hyperparasite distribution in France, with a negative relationship between non-growing season temperature and presence of the hyperparasite. Overall, our findings, in combination with earlier evidence, suggest that climatic factors are more important than species interactions in defining the niches of cryptic species within a pathogen complex on oak.

Written-Based Progress Testing: A Scoping Review

Abstract: Progress testing is an increasingly popular form of assessment in which a comprehensive test is administered to learners repeatedly over time. To inform potential users, this scoping review aimed to document barriers, facilitators, and potential outcomes of the use of written progress tests in higher education.The authors followed Arksey and O'Malley's scoping review methodology to identify and summarize the literature on progress testing. They searched 6 databases (Academic Search Complete, CINAHL, ERIC, Education Source, MEDLINE, and PsycINFO) on 2 occasions (May 22, 2018, and April 21, 2020) and included articles written in English or French and pertaining to written progress tests in higher education. Two authors screened articles for the inclusion criteria (90% agreement), then data extraction was performed by pairs of authors. Using a snowball approach, the authors also screened additional articles identified from the included reference lists. They completed a thematic analysis through an iterative process.A total of 104 articles were included. The majority of progress tests used a multiple-choice and/or true-or-false question format (95, 91.3%) and were administered 4 times a year (38, 36.5%). The most documented source of validity evidence was internal consistency (38, 36.5%). Four major themes were identified: (1) barriers and challenges to the implementation of progress testing (e.g., need for additional resources); (2) established collaboration as a facilitator of progress testing implementation; (3) factors that increase the acceptance of progress testing (e.g., formative use); and (4) outcomes and consequences of progress test use (e.g., progress testing contributes to an increase in knowledge).Progress testing appears to have a positive impact on learning, and there is significant validity evidence to support its use. Although progress testing is resource- and time-intensive, strategies such as collaboration with other institutions may facilitate its use.

Effectiveness of treated flax fibers in improving the early age behavior of high-performance concrete

Abstract: In recent years, ecoefficiency incentives have recently attracted growing research attention towards the valorization of natural fibers in cement systems. Specific attractive features of natural fibers include cost-effectiveness, abundance, renewability, and non-toxicity while providing several functionalities to concrete such as volumetric stability, strength enhancement, and crack control. This study is aimed at leveraging the hydrophilicity , hygroscopicity, and bridging capacity of flax fibers to design high-performance concrete (HPC) with controlled autogenous shrinkage . The effect of raw fibers and that of alkali-treated fibers on autogenous shrinkage of HPC and its fresh and mechanical properties were investigated and compared to the effect of shrinkage reducing admixture (SRA) and expanded shale lightweight aggregate (LWA). Results show that while SRA was found efficient in reducing autogenous shrinkage at 7 days (64% lower), this option adversely affected mixture flowability and mechanical performance (particularly flexural capacity). Similarly, LWA reduced autogenous shrinkage (by 36%) but without a noticeable effect on mechanical performance. Interestingly, the use of alkali-treated fibers allowed obtaining an HPC mixture with reduced autogenous shrinkage (26% lower) while maintaining improved flowability, compressive strength , and flexural capacity (up to 17% increase). Therefore, alkali-treated flax fibers can be viewed as a viable tool for mitigating autogenous shrinkage, thereby offering a green alternative promoting the sustainability of the built environment.