Study of the extraction of cobalt(II) from sulphate medium by using capric acid dissolved in chloroform

In this work we have first investigated the extraction of cobalt(II) from sulphate medium using capric acid dissolved in chloroform and then the effect of other diluents on the extraction process at 25°C. This study aims to understand the behaviour followed by this metal or, in other words, find its stoichiometry at the end of the extraction. This deportment is strongly dependent on many parameters like pH of the aqueous solution, acid concentration and the nature of the solvent. Each one of these parameters will be discussed. Temperature is another parameter that will be studied in this work. At the end of this research, we have found that stoichiometry of Co(II) complex is of the type CoA2(HR)2 (HR is an abridgment of capric acid). The equilibrium constant Kex and the thermodynamic parameters ΔH°, ΔS°, and ΔG° have been evaluated.Keywords: Capric acid; Cobalt(II); Sulphate medium; Solvent polarity, Temperature effect

The relationship between physical activity and quality of life during the confinement induced by COVID-19 outbreak: a pilot study in Tunisia

The present study aimed to determine the relationship between physical activity (PA) and quality of life (QoL) during the confinement caused by the COVID-19 outbreak. 216 participants (men: n = 112, women: n= 114) were included in the present study. They were divided into three groups (i.e., inactive group [IG]: less than 600 Metabolic Equivalent of Tasks (METs), n = 131; minimally active group [MAG]: from 600 to 2999 METs, n = 49; and health-enhancing PA group [HEPAG]: 3000 + METs, n = 36) based on their habitual PA level in the period of confinement. World Health Organization Quality of Life Instrument-Short Form (WHOQOL-Bref) and International Physical Activity Questionnaire-Bref (IPAQ-Bref) questionnaires were used to assess QoL and PA intensities. The main findings of the present study showed that MAG and HEPAG have better total PA, physical, psychological, social, and environmental QoL domains scores than IG (all, p<0.01). Small to large correlations (r ranging 0.14-0.72) were also observed between total PA, total walking activity, total moderate-intensity PA, total vigorous-intensity PA and QoL domains (all, p<0.01). PA with light- moderate- and vigorous intensities can be well recommended to decrease the negative psychosocial effect of confinement. However longitudinal studies are needed to draw causal inferences and underpin more robust and evidence-based and informed recommendations

Solvent extraction of nickel(II) from sulphate solution using capric acid

In this work we have studied the extraction of nickel(II) from a sulphate medium with capric acid noted (HA) in chloroform at 25°C in this study we will try to understand the behavior of this metal by varying a set of parameters like pH , the extractant concentration, polarity of solvent, effect of temperature on the extraction of this metal was also discussed. stoïchiometry of extracted species in the organic phase is NiR2(HR)2 , the equilibrium constants have been evaluated as well as thermody

Development of a boost-inverter converter under electromagnetic compatibility stress equipping a photovoltaic generator

Introduction. Static converters are among the most widely used equipment in several applications, for example, electric power transmission, motor speed variation, photovoltaic panels, which constitute the electronic components. The design of a power electronics device is done without any real means of predicting electromagnetic disturbances during the product development phase. This case-by-case development process is repeated until a solution is found that best respects all the electromagnetic compatibility constraints. The purpose is the development of a boost-inverter converter under electromagnetic compatibility constraints. The improvements made to the inverter are mainly in the control, the choice of power switches and the electromagnetic compatibility solutions brought to the device. The quality of the wave is improved by acting on the type of control and the choice of switches. Methods. In the first time, we have highlighted a comparison between two most frequently used power components (MOSFET and IGBT) in the inverter and the boost by simulation using ISIS and LT-spice softwares. The sinusoidal voltage with modulation circuit is greatly simplified by the use of the PIC16F876A microcontroller. In a second step, we validate the obtained results with experimental measurements. We start with the boost, then the inverter. In addition, the circuits made are housed in boxes to avoid accidental contact for people. The equipment is designed to isolate the load from the power supply in case of: over voltages, under voltages, high and low battery level and short circuits. Results. All the simulations were performed using the ISIS and LT-spice softwares. The obtained results are validated by experimental measurements performed in the ICEPS Laboratory at the University of Sidi Bel-Abbes in Algeria. The realization of a single-phase inverter with a pulse width modulation control, associated with a boost chopper and the waveforms of the current and voltage across each static converter its opening are presented. The sources of disturbances in power devices are at the origin of the temporal and frequency characteristics of the signals coming from the hot spots of the power switches and the resonances created during the switching of these elements.Вступ. Статичні перетворювачі відносяться до обладнання, що найбільш широко використовується в декількох застосуваннях, наприклад, для передачі електроенергії, зміни швидкості двигуна, у фотогальванічних панелях, які складають електронні компоненти. Проєкт устрою силової електроніки виконується без будь-яких реальних засобів прогнозування електромагнітних перешкод на етапі розробки продукту. Цей процес індивідуальної розробки повторюється доти, доки знайдено рішення, яке найкраще враховує всі обмеження електромагнітної сумісності. Метою є розробка підвищувально-інверторного перетворювача при обмеженнях за електромагнітною сумісністю. Удосконалення, внесені в інвертор, в основному стосуються управління, вибору силових вимикачів та рішень щодо електромагнітної сумісності, реалізованих у пристрої. Якість хвилі покращується за рахунок впливу на тип керування та вибір перемикачів. Методи. Вперше ми підкреслили порівняння між двома найбільш часто використовуваними силовими компонентами (MOSFET та IGBT) в інверторі та підвищенням шляхом моделювання з використанням програмного забезпечення ISIS та LT-spice. Синусоїдальна напруга зі схемою модуляції значно спрощується за рахунок використання мікроконтролера PIC16F876A. На другому етапі ми підтверджуємо отримані результати експериментальними вимірами. Починаємо з Boost, потім з інвертора. Крім того, виготовлені схеми розміщені в коробках, щоб уникнути випадкового дотику людей. Устаткування призначене для відключення навантаження від джерела живлення у разі: перенапруги, зниженої напруги, високого та низького рівня заряду батареї та короткого замикання. Результати. Усі розрахунки проводилися з використанням програм ISIS та LT-spice. Отримані результати підтверджені експериментальними вимірами, проведеними в лабораторії ICEPS Університету Сіді-Бель-Аббес в Алжирі. Представлено реалізацію однофазного інвертора з керуванням на базі широтно-імпульсної модуляції, пов'язаного з підвищуючим переривником, а також осцилограми струму та напруги на кожному відкритті його статичного перетворювача. Джерелами збурень у силових пристроях є часові та частотні характеристики сигналів, що надходять від гарячих точок силових ключів, та резонанси, що створюються при комутації цих елементів

Effect of Taekwondo Practice on Cognitive Function in Adolescents with Attention Deficit Hyperactivity Disorder.

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neuro-developmental/behavioral disorders among adolescents. Sport and physical activity seem to play a major role in the development of cognition, memory, selective attention and motor reaction time, especially among adolescents with ADHD. In this context, the objective of this study was to investigate the effects of a one-and-a-half-year-long Taekwondo (TKD) intervention on cognitive function in adolescents with ADHD. Two cognitive instruments, namely the Stroop and the Ruff 2 and 7 tests, were administered to assess attentional inhibitory control and sustained and selective visual attention, respectively. Comparisons between the TKD and control groups at baseline did not reveal significant differences. For post-test scores, there were statistically significant differences on the Stroop color block test (large effect size or ES = 1.26 [95% confidence interval or CI 0.30⁻2.22]), the color-word interference test (large ES = 2.16 [95% CI 1.10⁻3.26]), the interference test (large ES = 1.63 [95% CI 0.62⁻2.64]) and error (large ES = -2.20 [95% CI -3.31 to -1.10]). Similar trends were reported for the Ruff 2 and 7 automated detection trials (large ES = 2.78 [95% CI 1.55⁻4.01]), controlled search trials (large ES = 2.56 [95% CI 1.38⁻3.75]) and total speed (large ES = -2.90 [95% CI -4.15 to -1.64]). In conclusion, TKD practice increased selective attention in adolescents with ADHD. Practitioners should implement martial art programs in their general plans to favorably influence attention and health in adolescents with ADHD

The Effect of Mental Fatigue on Cognitive and Aerobic Performance in Adolescent Active Endurance Athletes: Insights from a Randomized Counterbalanced, Cross-Over Trial

The aim of this randomized counterbalanced, 2 × 2 cross-over study was to investigate the effects of mental fatigue on cognitive and aerobic performance in adolescent active endurance athletes. Ten active male endurance athletes (age = 16 ± 1.05 years, height = 1.62 ± 0.54 m, body mass = 55.5 ± 4.2 kg) were familiarized to all experimental procedures on day 1. On days 2 and 3, participants provided a rating of mental fatigue before and after completing a 30 min Stroop test that measures selective attention capacity and skills and their processing speed ability (mentally fatigued condition), or a 30 min control condition in a randomized counterbalanced order. They then performed d2 test and a 20 m multistage fitness test (MSFT), which was used to measure selective and sustained attention and visual scanning speed (i.e., concentration performance (CP) and total number of errors (E)) and aerobic fitness (i.e., maximum oxygen uptake (VO2max) and velocity at which VO2max occurs (vVO2max)), respectively. Rating of perceived exertion (RPE) was assessed after a MSFT. Subjective ratings of mental fatigue were higher after the Stroop task (p < 0.001). CP (p = 0.0.1), E (p < 0.001), vVO2max (p = 0.020), and estimated VO2max (p = 0.021) values were negatively affected by mental fatigue. RPE were significantly higher in the mentally fatigued than in the control conditions (p = 0.02) post-MSFT. Mental fatigue impairs aerobic and cognitive performance in active male endurance athletes

The Relationship between Cognitive Function, Lifestyle Behaviours and Perception of Stress during the COVID-19 Induced Confinement: Insights from Correlational and Mediation Analyses

Background: Home confinement during the COVID-19 outbreak may affect lifestyle behaviours, such as daily physical activity, social relationships, eating behaviours, and sleep, among others, which in turn may compromise mental health and psychological states. The aim of the present study was to determine the effects of COVID-19-induced home confinement on stress, attention, and lifestyle behaviours and the correlations between them. Methods: Participants included 144 students (aged 18–22 years, 62.5% female, 89.5% single). Stress, attention, and lifestyle behaviours were assessed using the Perceived Stress Scale (PSS), d2 test, and the Simple Lifestyle Indicator Questionnaire adapted and modified (SLIQ), respectively. Total PSS score, concentration performance (CP), errors (E), and lifestyle behaviours (e.g., diet, exercise/activity, alcohol, and smoking) before and during confinement were calculated. Results: The data showed a significant difference between before and during confinement in total PSS, CP, E, and all lifestyle behaviours (all, p < 0.05). Significant correlations existed between total PSS score, CP, E, and lifestyle behaviours (r= −87–98, all, p < 0.05). Conclusions: Home confinement has a negative effect on stress, attention, and lifestyle behaviours. This study suggests that the adoption of proper lifestyle behaviours, particularly diet, disciplined hygiene, and physical activity, boost health, psychological states, and cognitive function during COVID-19-induced confinement

Effects and Dose-Response Relationships of Motor Imagery Practice on Strength Development in Healthy Adult Populations: a Systematic Review and Meta-analysis.

BACKGROUND: Motor imagery (MI), a mental simulation of a movement without overt muscle contraction, has been largely used to improve general motor tasks. However, the effects of MI practice on maximal voluntary strength (MVS) remain equivocal. OBJECTIVES: The aims of this meta-analysis were to (1) estimate whether MI practice intervention can meaningfully improve MVS in healthy adults; (2) compare the effects of MI practice on MVS with its combination with physical practice (MI-C), and with physical practice (PP) training alone; and (3) investigate the dose-response relationships of MI practice. DATA SOURCES AND STUDY ELIGIBILITY: Seven electronic databases were searched up to April 2017. Initially 717 studies were identified; however, after evaluation of the study characteristics, data from 13 articles involving 370 participants were extracted. The meta-analysis was completed on MVS as the primary parameter. In addition, parameters associated with training volume, training intensity, and time spent training were used to investigate dose-response relationships. RESULTS: MI practice moderately improved MVS. When compared to conventional PP, effects were of small benefit in favour of PP. MI-C when compared to PP showed unclear effects. MI practice produced moderate effects in both upper and lower extremities on MVS. The cortical representation area of the involved muscles did not modify the effects. Meta-regression analysis revealed that (a) a training period of 4 weeks, (b) a frequency of three times per week, (c) two to three sets per single session, (d) 25 repetitions per single set, and (e) single session duration of 15 min were associated with enhanced improvements in muscle strength following MI practice. Similar dose-response relationships were observed following MI and PP. CONCLUSIONS: The present meta-analysis demonstrates that compared to a no-exercise control group of healthy adults, MI practice increases MVS, but less than PP. These findings suggest that MI practice could be considered as a substitute or additional training tool to preserve muscle function when athletes are not exposed to maximal training intensities

Allopatric diversification and evolutionary melting pot in a North African Palearctic relict: the biogeographic history of Salamandra algira

North Africa is a climatically and topographically complex region with unique biotic assemblages resulting from the combination of multiple biogeographic realms. Here, we assess the role of climate in promoting intra-specific diversification in a Palearctic relict, the North African fire salamander, Salamandra algira, using a combination of phylogenetic and population genetic analyses, paleoclimatic modelling and niche overlap tests. We used mitochondrial DNA (Cyt-b), 9838 ddRADseq loci, and 14 microsatellite loci to characterize patterns of genetic diversity and population structure. Phylogenetic analyses recover two major clades, each including several lineages with mito-nuclear discordances suggesting introgressive patterns between lineages in the Middle Atlas, associated with a melting pot of genetic diversity. Paleoclimatic modelling identified putative climatic refugia, largely matching areas of high genetic diversity, and supports the role of aridity in promoting allopatric diversification associated with ecological niche conservatism. Overall, our results highlight the role of climatic microrefugia as drivers of populations’ persistence and diversification in the face of climatic oscillations in North Africa, and stress the importance of accounting for different genomic regions when reconstructing biogeographic processes from molecular markers

The Effects of Physical Training on Quality of Life, Aerobic Capacity, and Cardiac Function in Older Patients With Heart Failure: A Meta-Analysis

Aim: The purposes of this meta-analysis were to quantify the effectiveness of physical training on quality of life (QoL), aerobic capacity, and cardiac functioning in older patients with heart failure (HF) and evaluate dose–response relationships of training variables (frequency, volume, and duration).Methods: Scholarly databases (e.g., PubMed/MEDLINE, Google Scholar, and Scopus) were searched, identifying randomized controlled trials that investigated the effectiveness of different training modes on QoL (assessed by the Minnesota Living with Heart Failure Questionnaire), aerobic capacity (assessed by the 6 min walk test) and cardiac function (assessed by left ventricular ejection fraction).Results: Twenty five studies were included with a total of 2,409 patients. Results showed that exercise training improved total QoL (small ES = −0.69; 95% CI −1.00 to 0.38; p &lt; 0.001), aerobic capacity (small ES = 0.47; 95% CI 0.15–0.71; p = 0.002) and cardiac function (moderate ES = 0.91; 95% CI 0.37–1.45; p = 0.001). In addition, univariate analyses revealed the moderating variable ‘training mode' significantly influenced aerobic capacity (Q = 9.97; p = 0.007), whereby, resistance training had the greatest effect (ES = 1.71; 95% CI 1.03–2.39; p &lt; 0.001), followed by aerobic training (ES = 0.51; 95% CI 0.30–0.72; p &lt; 0.001), and combined training (ES = 0.15; 95% CI −0.24 to 0.53; p = 0.45). Meta-regression analysis showed that only the duration of an intervention predicted the effect of physical training on QoL (coefficient = −0.027; p = 0.006), with shorter training durations (12 weeks) showing larger improvements.Conclusion: The present meta-analysis showed that physical training has positive effects on QoL, aerobic capacity, and cardiac function in older patients with HF. Practitioners should consider both training volume and mode when designing physical training programs in order to improve QoL and aerobic capacity in older patients with HF