Synthesis, characterization and magnetic properties of four new organically templated metal sulfates [C5H14N2][M(II)(H2O)6](SO4)2, (M(II) = Mn, Fe, Co, Ni).

International audienceA series of novel organically templated metal sulfates, [C(5)H(14)N(2)][M(II)(H(2)O)(6)](SO(4))(2) with (M(II) = Mn (1), Fe (2), Co (3) and Ni (4)), have been successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, thermogravimetric analysis and magnetic measurements. All compounds were prepared using a racemic source of the 2-methylpiperazine and they crystallized in the monoclinic systems, P2(1)/n for (1, 3) and P2(1)/c for (2,4). Crystal data are as follows: [C(5)H(14)N(2)][Mn(H(2)O)(6)](SO(4))(2), a = 6.6385(10) Å, b = 11.0448(2) Å, c = 12.6418(2) Å, β = 101.903(10)°, V = 906.98(3) Å(3), Z = 2; [C(5)H(14)N(2)][Fe(H(2)O)(6)](SO(4))(2), a = 10.9273(2) Å, b = 7.8620(10) Å, c = 11.7845(3) Å, β = 116.733(10)°, V = 904.20(3) Å(3), Z = 2; [C(5)H(14)N(2)][Co(H(2)O)(6)](SO(4))(2), a = 6.5710(2) Å, b = 10.9078(3) Å, c = 12.5518(3) Å, β = 101.547(2)°, V = 881.44(4) Å(3), Z = 2; [C(5)H(14)N(2)][Ni(H(2)O)(6)](SO(4))(2), a = 10.8328(2) Å, b = 7.8443(10) Å, c = 11.6790(2) Å, β = 116.826(10)°, V = 885.63(2) Å(3), Z = 2. The three-dimensional structure networks for these compounds consist of isolated [M(II)(H(2)O)(6)](2+) and [C(5)H(14)N(2)](2+) cations and (SO(4))(2-) anions linked by hydrogen-bonds only. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers. The magnetic measurements indicate that the Mn complex (1) is paramagnetic, while compounds 2, 3 and 4, (M(II) = Fe, Co, Ni respectively) exhibit single ion anisotropy

Development of chitosan-gelatin nanofibers with cellulose nanocrystals for skin protection applications

In this work, natural-based and biodegradable nanofibers were produced by electrospinning for drug delivery and wound dressing applications, using gelatin (Gel), chitosan (CS), cellulose nanocrystals (CNC) and natural propolis extract. The polymeric formulations and electrospinning parameters were optimized, resulting in the development of Gel/CS nanofibers with mean diameters of 97 nm. CNC were successfully introduced into the optimized Gel/CS solution and the viscosity and conductivity values were recorded. The developed nanofibers were characterized using FESEM, ATR-FTIR, TGA and WCA. The incorporation of different CNC concentrations improved the solutions’ electrospinnability and the membranes’ physical integrity. Defect-free and uniform Gel/CS/CNC nanofibers were observed by FESEM images, and the fibers’ diameters slight increased. The hydrophilic character was maintained after the CNC incorporation. Finally, Gel/CS/CNC/Propolis nanofibers demonstrated antibacterial activity against both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteriaThe authors are thankful to TSSiPRO project, operation code NORTE01-0145-FEDER-000015. The authors are also grateful to FCT, Portugal for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020) and to 2C2T (UID/CTM/00264/2019). D. P. Ferreira thank the national funding by FCT through the individual scientific employment program-contract (CEECIND/02803/2017) and S. M. Costa thank the FCT PhD Scholarship (SFRH/BD/147517/2019)

Thermal Performance of Hybrid PVT Collector with Natural Circulation

Hybrid photovoltaic thermal (PVT) collectors allow simultaneous production of electrical energy thus heat energy. There are several configurations of hybrid collectors (to produce water or air). For hybrids water collectors, there are several configurations that differ by the nature of the absorber (serpentine, tubes...). In this paper, an absorber tank is studied. The circulation of the coolant is natural (we do not use the pump). We present the obtained results in our experimental study and we analyzed the data, and then we compare the results with the theory practices. The electrical performances of the hybrid collector are compared with those of conventional photovoltaic module mounted on the same structure and measured under the same conditions. We conducted experiments with natural circulation of the coolant (Thermosyphon), for a flow rate of 0.025kg/m²

Comparison of different adjustment models of the growth curve of Barbarin lambs under two bioclimatic zones in Tunisia

L’objectif de cette étude est d’analyser les performances de croissance de la race ovine Barbarine avec ses deux principaux écotypes (Barbarine à tête rousse et la Barbarine à tête noire) sous deux différents étages bioclimatiques (aride et semi-aride) ainsi que d’ajuster la courbe de croissance de cette race. On a utilisé les données de contrôle de croissance de vingt troupeaux de race ovine Barbarine, collectées durant 4 années, concernant 12 919 agneaux pesés à 21 jours d’intervalle. Les poids aux âges types ainsi que les Gains moyens Quotidiens (GMQ) 10-30, 30-50, 50-70 et 70-90 de la race Barbarine à tête rousse sont supérieurs à ceux de la Barbarine à tête noire. Les poids aux âges types de la Barbarine à tête rousse sont de 5,33 Kg, 8,50 Kg, 11,5 Kg, 15,2 Kg et 17,7 Kg respectivement pour les poids à 10, 30, 50, 70 et 90 jours. Celles des gains moyens sont de 160,3 g, 163,4g, 219,2 g et 157,5 g respectivement pour les GMQ10-30, GMQ30-50, GMQ30-70 et GMQ30-90. De même, les performances de croissance enregistrées sous l’étage bioclimatique aride sont supérieures à celles de l’étage semi-aride. L’ajustement des courbes de croissance a été effectué selon quatre modèles mathématiques non linéaires (Brody, Logistique, Gompertz et Von Bertalanffy). Ces modèles ont été évalués en fonction du coefficient de détermination (R²) et de la somme des carrées des écarts résiduels (SCER). Les résultats ont indiqué que le modèle Logistique, ayant les valeurs de R² les plus élevées et les SCER les plus faibles, a montré le meilleur ajustement de la croissance des agneaux barbarins, alors que le modèle de Brody a donné les valeurs de R² les plus basses et les SCER les plus élevées. Les paramètres de la fonction Logistique (A, B et C) sont respectivement de 17,9 ; 4,1 et 0,0381 pour la Barbarine à tête noire et de 18,8, 4,00 et 0,0406 pour la Barbarine à tête rousse. Les paramètres des courbes de croissance ont varié avec l’interaction écotype – étage bioclimatique, la ferme, l’interaction troupeau – année d’agnelage, l’âge de la mère, l’interaction  sexe – mode de naissance et le mois de naissance. Mots clés: Courbe de croissance, modèle non linéaire, race BarbarineThe objective of this study is to analyze the growth performance of the Barbarine sheep breed with its two main ecotypes (Red-headed Barbarine and Black-headed Barbarine) under two different bioclimatic zones (arid and semi-arid) as well as to adjust the growth curve of this breed. Growth monitoring data from twenty flocks of Barbarine sheep were used, collected over 4 years on 12 919 lambs weighed regularly at 21-day intervals. The weights at the standard ages as well as Averge Daily Gains (ADG) 10-30, 30-50, 50-70 and 70-90 of the Red-headed Barbarine are higher than that of the Black-headed Barbarine. The average weights at typical ages of the Red-headed Barbarine were 5.33 Kg, 8.50 Kg, 11.5 Kg, 15.2 Kg and 17.7 Kg respectively at 10, 30, 50, 70 and 90 days. Those of the ADG were 160.3 g, 163.4 g, 219.2 g and 157.5 g respectively for the ADG10-30, ADG 30-50, ADG 30-70 and ADG 30-90. Similarly, the growth performances recorded under the arid bioclimatic zone were higher than those of the semi-arid zone. The adjustment of the growth curves was carried out according to four nonlinear mathematical models (Brody, Logistics, Gompertz and Von Bertalanffy). These models were evaluated based on the coefficient of determination (R²) and the sum of squares of residual deviations (SCER). The results indicated that the Logistic model, having the highest R² values ??and the lowest SCERs, showed the best fit for Barbarin lamb growth while Brody's model gave the lowest R² values ??and the highest SCERs. The Logistic function parameters (A, B and C) were respectively 17.9, 4.08 and 0.0381 for the black-headed barbarine and 18.8, 4.00 and 0.0406 for the Red-headed Barbarine. These parameters varied with the interaction ecotype – bioclimatic zone, the farm, the interaction herd – year of lambing, the age of the mother, the interaction sex – mode of birth and the month of birth. Keywords: growth curve, nonlinear model, Barbary breed

Adjustment of the lactation curve of Holstein cows according to Wood's model

Les deux objectifs de cette étude ont été d’ajuster les courbes de lactation des vaches Holstein en Tunisie et d’étudier les facteurs de variations des paramètres de ces dernières. L’ajustement a été réalisé selon le modèle de Wood pour les 9 premières lactations. Les données proviennent de 190 905 contrôles journaliers de la quantité de lait, de la matière grasse (MG) et de la matière protéique (MP), collectés entre 1995 et 2011 et répartis sur 10 troupeaux issus de 4 différents secteurs de production. La fonction de Wood a servi pour modéliser les courbes de lactations par la régression non linéaire. Les paramètres de la courbe de lactation «a», MG et MP les plus élevées ont été enregistrés à la 3ème, 4èmeet 5ème lactation, contrairement au paramètre «b». Le paramètre «c» et la persistance la plus élevée de la courbe de lactation ont été enregistrés à la 1ère lactation. Pour les paramètres des courbes de lactation et ses traits (lait, MG et MP), ils ont tous été affectés par les facteurs inclus dans le modèle d’analyse à savoir le secteur, le troupeau, l’interaction année de vêlage-saison de vêlage et le numéro de lactation. Mots clés: Contrôles journaliers, ajustement, Wood, courbe de lactationThe two objectives of this study were to adjust the lactation curves of Holstein cows in Tunisia and to study the factors of variation of the parameters of the latter. The adjustment was made according to the Wood model for the first 9 lactations. The data comes from 190,905 daily checks of the quantity of milk, fat (MG) and protein (MP), collected between 1995 and 2011 and distributed over 10 herds from 4 different production sectors. Wood's function was used to model the lactation curves by nonlinear regression. The highest “a”, MG and MP lactation curve parameters were recorded at the 3rd, 4th and 5th lactation, unlike the “b” parameter. The “c” parameter and the highest persistence of the lactation curve were recorded in the 1st lactation. For the parameters of the lactation curves and its traits (milk, fat and protein), they were all affected by the factors included in the analysis model, namely the sector, the herd, the interaction year of calving - calving season and lactation number. Keywords: Daily checks, adjustment, Wood, lactation curv

Application of a Novel Synergetic Control for Optimal Power Extraction of a Small-Scale Wind Generation System with Variable Loads and Wind Speeds

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).The synergetic control technique (SCT) has the solution for understanding the symmetry inherent in the non-linear properties of wind turbines (WTs); therefore, they achieve excellent performance and enhance the operation of the WT. Small-scale WTs are efficient and cost-effective; they are usually installed close to where the generated electricity is used. This technology is gaining popularity worldwide for off-grid electricity generation, such as in rural homes, farms, small factories, and commercial properties. To enhance the efficiency of the WT, it is vital to operate the WT at its maximum power. This work proposes an efficient and fast maximum power point tracking (MPPT) technique based on the SCT to eradicate the drawbacks of the conventional methods and enhance the operation of the WT at the MPP regardless of wind speed and load changes. The SCT has advantages, such as robustness, simplified design, fast response, no requirement for knowledge of WT characteristics, no need for wind sensors or intricate power electronics, and straightforward implementation. Furthermore, it improves speed convergence with minimal steady-state oscillations at the MPP. The investigated configuration involves a wind-driven permanent magnet synchronous generator (PMSG), uncontrolled rectifier, boost converter, and variable load. The two converters are used to integrate the PMSG with the load. Three scenarios (step changes in wind speed, stochastic changes in wind speed, and variable electrical load) are studied to assess the SCT. The results prove a high performance of the suggested MPPT control method for a fast convergence speed, boosted WT efficacy, low oscillation levels, and applicability under a variety of environmental situations. This work used the MATLAB/Simulink program and was then implemented on a dSPACE 1104 control board to assess the efficacy of the SCT. Furthermore, experimental validation on a 1 kW Darrieus-type WT driving a PMSG was performed.Peer reviewe

<i>Virgatasporites</i> and <i>Attritasporites</i>: the oldest land plant derived spores, cryptospores or acritarchs?

peer reviewe

Hydrothermal synthesis of (C5H14N2)[CoCl4]⸳0.5H2O: Crystal structure, spectroscopic characterization, thermal behavior, magnetic properties and biological evaluation

The organic-inorganic compound (C5H14N2)[CoCl4]⸳0.5H2O, I, was characterized by various physicochemical techniques. The X-ray diffraction analysis revealed that the compound crystallizes in the centrosymmetric space group C2/c of the monoclinic system. The atomic arrangement the Co(II) complex is built from isolated [CoCl4]2– anions, 1-methylpiperazine-1,4-diium [C5H14N2]2+ cations and free water molecules. The crystal structure study showed that the cohesion of I is assured through N–H···Cl and N–H···O hydrogen bonds giving birth to a 3-D architecture. Hirshfeld surface analysis revealed that Cl···H/H···Cl and H···H (58.5 and 36.4%, respectively) are the most significant interactions between species. Minor O···H/H···O interactions are also present. The compound was characterized by thermal analysis, TGA-DTA showed the removal of the co-crystallized water before 100 °C and a first mass loss at around 120 °C. Magnetic measurements are in good agreement with isolated, S = 3/2, tetrahedral [CoCl4]2− anions. The negative Weiss constant of -1.35 indicates single-ion anisotropy and very weak antiferromagnetic interactions. UV–visible spectroscopy reveals three weak absorption bands in the visible range due to the d-d electronic transitions typical of the Co(II) tetra-coordinated. A bioassay showed antibacterial activity against the gram negative Klebsiella pneumonia and gram positive Bacillus ceureus, Listeria monocytogenes, and Micrococcus lutues