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Natural esters for green transformers: challenges and keys for improved serviceability
Get PDFThe service of mineral insulating oils for power transformer insulation and cooling aspects cannot be disavowed. However, the continued use of mineral oils is questionable due to environmental unfriendliness and the divestment from fossil fuels. This has provoked the quest for green alternative insulating liquids for high-voltage insulation. Natural esters are among the remaining alternatives that are renewable and environmentally friendly. Regardless of their environmental and technical merits, natural esters have some limitations that are slowing down their total acceptance by transformer owners and utilities. Critical limitations and concerns include esters’ pour point, viscosity, oxidative stability, and ionization resistance. In this work, the state of the art of “natural esters for transformers” is explored with the aim of potential improvements. The sections of the article are geared towards technical viewpoints on improving the overall workability and serviceability of natural esters in high-voltage applications. A comprehensive review of the existing literature is achieved, based on performance improvements of the natural ester using “additives” and “chemical modification”. The authors hope that this report may be helpful to transformer owners as well as influence the progression of natural esters for power transformer applications
Effect of the use of a cream with leucine and lactic acid associated with electrostimulation in contouring and facial tonus: A randomized clinical controlled trial
Get PDFEvidence has supported the use of leucine as a promising agent for the maintenance of muscle tone. This study aimed to assess the combined effect of leucine and cream-based lactic acid (novel cosmetic product), associated with the use of surface electrical stimulation to improve contour and facial tonus in women. A total of 23 women were randomly allocated into two groups: Experimental (EG)—use of the leucine-based cream and lactic acid + electrostimulation for facial toning (mean intensity 13 Hz and protocol in progression); and placebo (GP)—use of the placebo cream (without the addition of leucine and lactic acid) + stimulation with the same protocol as the EG. Each group used their cream daily and underwent the intervention protocol three x/week with stimulation for 40 min, for a total of 8 weeks. Three main outcomes were reported: angular variation of facial contour by means of photogrammetry, muscle tone through the electromyographic activity of the masseter and zygomatic muscles during rest and functional tasks of biting and smiling. A significant effect of the intervention and between the groups was obtained for the experimental group against the placebo group for facial contour and muscle tone. An increased muscular activity of the masseter (average 28%) when smiling, and a reduction of zygomatic activity (in average 41%) when biting were found. The use of cream containing leucine and lactic acid combined with electrostimulation contributes to the improvement of facial contour and muscle tone when biting and smiling
High‐intensity interval training combined with blood‐flow restriction predominantly alters anaerobic capacity in endurance‐trained athletes
No full textBlood-flow restriction (BFR) training has gained popularity amongst athletes and sport practitioners to enhance training adaptations and performance. However, BFR has typically been associated with low-intensity exercise, and there is still limited evidence of its impact when combined with high-intensity training. This study investigated the impact of high-intensity interval training (HIIT) with concurrent BFR on anaerobic and aerobic physical capacities and key physiological responses. In a pre-post, parallel-groups design, fifteen endurance-trained males (VO2max 65.0±4.8 mL/min/kg) included three sessions of HIIT per week (sets of 15 s ON/15 s OFF at 100% maximal aerobic power) into their usual training for three weeks either with (BFR group, n=9) or without restriction (CTL group, n=6). In BFR, cuffs were worn proximal on both quadriceps and inflated progressively from 50 to 70% of arterial occlusion pressure across training weeks. Before and after training, athletes completed a maximal incremental step cycling test, a Wingate anaerobic test (WAnT) and a 5-km cycling time trial. Blood samples were drawn during the time trials. Maximal aerobic power increased in BFR (364.8±60.7 vs 383.4±61.4 watts, p=0.003, Cohen’s effect size ES 0.27) but not in CTL (381.2±62.1 vs 385.5±64.4 watts, p=0.45, ES 0.05). Concomitantly, mean power output achieved during the WAnt also increased with BFR (23.8±4.0 vs 24.6±4.1 kJ, p=0.08, ES 0.28) but not in CTL (23.4±2.5 vs 23.4±2.4 kJ, p=0.95, ES 0.01). However, there was no change between groups in VO2max (BFR: 0.86% vs CTL: 1.77%, ES -0.15) and in both the mean power output (BFR: 1.81% vs CTL: 6.51%, ES -0.21) and completion time (BFR: -0.69% vs CTL: -2.55%, ES -0.21) of the 5-km time trial. During the time trial, BFR also induced greater changes in pH (BFR: -0.05 vs CTL: -0.03 units, ES -0.43) and base excess (BFR: -1.55 vs CTL: -0.70 units, ES -0.37), and lowered the potassium ion concentration (BFR: -0.55 vs CTL: 0.44 mmol/L, ES -0.63). There was no change between groups in lactate production from pre- to post-training. These findings suggest that short-term HIIT combined with BFR improved anaerobic capacity in endurance-trained athletes without meaningful effect on endurance exercise performance
Clearance of defective muscle stem cells by senolytics reduces the expression of senescence-associated secretory phenotype and restores myogenesis in myotonic dystrophy type 1
Get PDFMuscle weakness and atrophy are clinical hallmarks of myotonic dystrophy type 1 (DM1). Muscle stem cells, which contribute to skeletal muscle growth and repair, are also affected in this disease. However, the molecular mechanisms leading to this defective activity and the impact on the disease severity are still elusive. Here, we explored through an unbiased approach the molecular signature leading to myogenic cell defects in DM1. Single cell RNAseq data revealed the presence of a specific subset of DM1 myogenic cells expressing a senescence signature, characterized by the high expression of genes related to senescence-associated secretory phenotype (SASP). This profile was confirmed using different senescence markers in vitro and in situ. Accumulation of intranuclear RNA foci in senescent cells, suggest that RNA-mediated toxicity contribute to senescence induction. High expression of IL-6, a prominent SASP cytokine, in the serum of DM1 patients was identified as a biomarker correlating with muscle weakness and functional capacity limitations. Drug screening revealed that the BCL-XL inhibitor (A1155463), a senolytic drug, can specifically target senescent DM1 myoblasts to induce their apoptosis and reduce their SASP. Removal of senescent cells re-established the myogenic function of the non-senescent DM1 myoblasts, which displayed improved proliferation and differentiation capacity in vitro; and enhanced engraftment following transplantation in vivo. Altogether this study presents a well-defined senescent molecular signature in DM1 untangling part of the pathological mechanisms observed in the disease; additionally, we demonstrate the therapeutic potential of targeting these defective cells with senolytics to restore myogenesis
Opening the black box of project team members’ competencies improvement in a public sector organization for a successful transition to the project society
Get PDFThe purpose of this paper is to investigate the project team member’s skill developmental activities within the
context of a public organization, as to suggest both a theoretical understanding and a procedure adapted for this
development, which is based on a reflective approach. The methodology used is based on a qualitative inductive
approach subject to a single case study. For an organization with a lightweight project matrix structure to
efficiently decentralize the various HR practices related to skill development, the skills evaluation must be selfadministered, the development plan and training activities are integrated into the project’s lessons learned
sessions and support is offered to the project team by an external party (coach). The developmental approach
through learning in an occupational environment also enables the organization to adapt to the project society
with collaborative and qualified management. This original research stems from its descriptive and comprehensive approach to adapt project management and HRM theories to inform public management
Role transitions at the prosumer level: Spillover effects in the collaborative economy from an interactive marketing perspective
Get PDFPurpose:
The purpose of this study is to examine the process underlying how consumers shift roles from users to suppliers of goods or services in the collaborative economy (CE). It examines quantatively the impact of a series of explanatory variables underlying that switchover process.
Design/methodology/approach:
This study identifies and tests the key factors that motivate the userprovider transition by introducing the spillover effect from the proenvironmental literature into collaborative practices and using four experimental designs. Considering behavioral characteristics, context, intrinsic variables and socialization, this study provides an in-depth understanding of the process of transition from
user to supplier in the CE.
Findings:
The results suggest the interactive nature of the spillover as peer influence boosts changes in individual motivations, preferences and behaviors. Furthermore, promoting solidarity between members of the CE platform facilitates the transition of participants from users to providers. In addition, the users’ perception of socialization, satisfaction and sense of indebtedness may also play a significant role in the transition.
Research limitations/implications:
The study highlights the process underlying the switchover from user to provider at the prosumer level. More specifically, this study identifies key variables influencing the intention to switchover in the CE by drawing on the spillover effect from pro-environmental behavior and considering the spillover as an interactive process.
Practical implications:
Managers who wish to develop collaborative systems must attract a critical mass of providers to ensure the viability of their systems. Instead of recruiting new providers, managers may convert existing users into providers. This study identifies the key variables to modulate to this end.
Originality/value:
The findings offer important managerial implications and shed new light on the CE literature
A Tool for Study on Impact of Big Data Technologies on Firm Performance
Get PDFOrganizations can use big data analytics to evaluate large data volumes and collect new information. It aids in answering basic inquiries concerning business operations and performance. It also aids in the discovery of unknown patterns in massive datasets or combinations of datasets. Overall, companies use big data in their systems to enhance operations, provide better customer service, generate targeted marketing campaigns, and take other activities that can raise revenue and profitability in the long run. Therefore, it’s becoming increasingly important to apply and analyze big data approaches for business growth in today’s data-driven world. More precisely, given the abundance of data available on the Internet, whether via social media, websites, online portals, or platforms, to mention a few, businesses must understand how to mine that data for meaningful insights. In this context, Web scraping is an essential strategy. As a result, this work aims to explain the application of the developed tool to the specific case of retrieving big data information about the particular companies in our sample. The paper starts with a short literature review about Web scraping then discusses the tools and methods utilized, describing how the developed technology was applied to the specific scenario of retrieving information about big data usage in the enterprises present in our sample
Ice nucleation on silicone rubber surfaces differing in roughness parameters and wettability: Experimental investigation and machine learning–based predictions
Get PDFSuperhydrophobic surfaces serving as icephobic surfaces are a passive means of limiting the icing of surfaces. Ice nucleation time depends on not only liquid properties and environmental conditions but also surface features; however, it is challenging to investigate ice nucleation time and the influencing parameters simultaneously. This manuscript presents two approaches, experimental testing and machine learning, to study ice nucleation time on exposed surfaces. Hydrophobic/superhydrophobic silicone rubber surfaces were fabricated, and these surfaces varied in their wettability and roughness parameters. Superhydrophobic surfaces characterized by a higher arithmetic average, root mean squared, ten-point height, maximum height of the profile, and a Gaussian roughness distribution—skewness near 0—had longer ice nucleation times. We then used neural networks to model icephobicity in relation to ice nucleation time. The predicted ice nucleation time of the model, trained using some of the experimental results, demonstrated a good agreement with the experimental outcomes. Furthermore, this machine learning approach determined the relative importance of roughness parameters, surface wettability, temperature, and droplet volume in determining surface icephobicity. The proposed approach provides a starting point for studying heterogeneous ice nucleation prediction through an understanding of the key parameters required to optimize the icephobic behavior of superhydrophobic surfaces
Multi-model approach to integrate climate change impact on carbon sequestration potential of afforestation scenarios in Quebec, Canada
Get PDFAfforestation of unproductive or currently non-forested territories can increase carbon land sinks and thus contribute to mitigate climate change. However, investments on large-scale afforestation could be risky because of the predicted effect of climate change on forest productivity of newly created plantations. The aim of this study was to assess the carbon sequestration and mitigation potential of afforestation scenarios with different species (Picea mariana, Picea glauca, Pinus banksiana, Pinus resinosa and Populus spp) on open woodlands and abandoned farmlands in the Province of Quebec (Canada) under different radiative forcing projections. We modelled carbon dynamics in these lands under three Representative Concentration Pathways projections (RCP 2.6, RCP 4.5, and RCP 8.5) over the 2021–2100 period. The forest gap model PICUS was used to model tree growth of afforested species as a function of the Representative Concentration Pathways 2.6, 4.5 and 8.5; these data were then used as input in the Carbon Budget Model – Canadian Forest Sector 3 to simulate the evolution of ecosystem carbon stocks and fluxes as a function of forest management and climate. Carbon transfer to harvested wood products, and carbon fluxes associated with product life cycles and substitution effects on markets, were also included in the analyses. Results showed that Pinus species responded more strongly to variations in radiative forcing than for the other simulated species. Overall, aboveground biomass was particularly altered by increased radiative forcing, which in turn reduced harvesting yield and transfers to wood processing and products. At the end of the simulation, despite the expected impacts of radiative forcing on ecosystems, afforestation scenarios on open woodlands with black spruce, white spruce, and jack pine can deliver carbon mitigation of 32% – 70% over the baseline scenario and 4% – 12% for red pine on abandoned farmlands and, hence, contribute to efforts to reduce GHG emissions, especially over the long term. Although climate change is expected to impact the growth of newly planted areas as part of afforestation efforts, the results of our study suggest that the choice of species to plant and the selected forest management strategy have a greater impact on carbon stocks than climate change itself. This study provides a better understanding of the dynamics of afforestation under climate change and whether investments in plantation can contribute to GHG reduction targets
Longitudinal follow-up of the asthma status in a French–Canadian cohort
Get PDFAsthma affects 340 million people worldwide and varies in time. Twenty years ago, in Canada, the Saguenay–Lac-Saint-Jean asthma family cohort was created to study the genetic and environmental components of asthma. This study is a follow-up of 125 participants of this cohort to explore the appearance, persistence, and progression of asthma over 10–20 years. Participants answered a clinical standardized questionnaire. Lung function was assessed (forced expiratory volume in 1 s, forced vital capacity, bronchial reversibility, and methacholine bronchoprovocation), skin allergy testing was performed, blood samples were obtained (immunoglobulin E, white blood cell counts) and phenotypes were compared between recruitment and follow-up. From the participants without asthma at recruitment, 12% developed a phenotype of adult-onset asthma with the presence of risk factors, such as atopy, high body mass index, and exposure to smoking. A decrease of PC20 values in this group was observed and a decrease in the FEV1/FVC ratio in all groups. Also, 7% of individuals with asthma at recruitment developed chronic obstructive pulmonary disease, presenting risk factors at recruitment, such as moderate-to-severe bronchial hyperresponsiveness, exposure to smoking, and asthma. This study allowed a better interpretation of the evolution of asthma. Fine phenotypic characterization is the first step for meaningful genetic and epigenetic studies