Structural stability and magnetic properties of Mn2FeAl alloy with a β-Mn structure

The synthesized Mn2FeAl alloys crystallize in a geometrically frustrated cubic β-Mn structure (space group: P4132) with an antiferromagnetic ordering whereas the previous theoretical findings suggest for a Heusler structure (L21: regular and X: inverse). The experimental stability of the structure is verified by electronic structure calculations performed for various arrangements of Mn, Fe and Al atoms in the β-Mn-type crystal structure. When compared the energy of the β-Mn structure with the energy of L21 and X type structures, it is found that for an expansion of the lattice volume β-Mn structure becomes more preferable in total energy than L21 and X-type structures. The calculated theoretical equilibrium lattice parameter value for the β-Mn2FeAl is within the accuracy of the experimental value obtained in this work. Additional DFT + U calculations for the optimized crystal structure of the β-Mn2FeAl revealed that the electronic correlations in the Mn ions result in the increased total magnetic moment. In the X type structure, Mn2FeAl is a half metal, whereas the disordered arrangement of atoms in the β-Mn structure leads to the closure of the semiconductor gap. The β- Mn2FeAl alloys exhibit antiferromagnetic ordering (TN ≈ 42 K), which is in excellent agreement with our electronic structure calculations. The detailed analysis of the magnetic and heat capacity measurements suggests a short-range magnetic ordering in the Mn2FeAl alloys. Owing to the strong antiferromagnetic spin fluctuation caused by the geometric frustration in β-Mn, a large enhancement in the electronic heat capacity is noticed. Mn2FeAl shows the characteristic features of spin glass as verified from the frequency dependent AC susceptibility analysis using critical power law and Vogel-Fulcher law. To the best of our knowledge, this is the first ever report on the theoretically predicted lowest ground state configuration for Mn2FeAl with a β-Mn structure and the experimental realization of spin glass features in this geometrically frustrated antiferromagnet. © 2020 Elsevier B.V.Department of Science and Technology, Ministry of Science and Technology, India, डीएसटी: - SB-FTP/PS097/2014, no-INT/ RUS / RFBR /379; University Grants Committee, UGC: F.30-49/2014; Science and Engineering Research Board, SERB; Russian Foundation for Basic Research, РФФИ: 19-52-45008, 20-02-00234; Inter-University Accelerator Centre, IUAC: UFR 57318; AAAA-A18-118020190098-5This work is financially supported by SERB -DST, New Delhi, India (Grant no - SB-FTP/PS097/2014 ) and DST New Delhi, India (Grant no-INT/ RUS / RFBR /379). The financial assistance provided by IUAC, New Delhi, India through Grant No. UFR 57318 and UGC, India Grant No. F. 30-49/2014 (BSR) is also acknowledged. Theoretical studies of β-Mn 2 FeAl are supported by the Russian Foundation for Basic Research (project nos. 19-52-45008 and 20-02-00234 ), theoretical studies of L2 1 , X-Mn 2 FeAl are supported by the state assignment of Minobrnauki of Russia (theme “Electron” No. AAAA-A18-118020190098-5).This work is financially supported by SERB-DST, New Delhi, India (Grant no- SB-FTP/PS097/2014) and DST New Delhi, India (Grant no-INT/RUS/RFBR/379). The financial assistance provided by IUAC, New Delhi, India through Grant No. UFR 57318 and UGC, India Grant No. F.30-49/2014(BSR) is also acknowledged. Theoretical studies of ?-Mn2FeAl are supported by the Russian Foundation for Basic Research (project nos. 19-52-45008 and 20-02-00234), theoretical studies of L21, X-Mn2FeAl are supported by the state assignment of Minobrnauki of Russia (theme ?Electron? No. AAAA-A18-118020190098-5)

Effect of kisspeptin on in vitro maturation of sheep oocytes

Aim: The aim of this study was to investigate the effect of kisspeptin (KP) on in vitro maturation (IVM) of sheep oocytes aspirated from the ovaries collected from slaughterhouse. Materials and Methods: Two different experiments were conducted to investigate the effect of KP (5, 10 and 15 μg/ml) alone (experiment 1) or in combination with follicle-stimulating hormone (FSH), luteinizing hormone (LH), and Estradiol (E2) (experiment 2) on IVM of sheep oocytes. Tissue culture medium 199 supplemented with Gentamicin was used as control medium. Good quality oocytes were randomly allocated into different IVM media and cultured at 38.5°C in 5% CO2 under humidified atmosphere for 24 h. The oocytes were evaluated for their cumulus cell expansion (CCE) and extrusion of the 1st polar body (PB) at the end of maturation. Results: The proportion of oocytes showing CCE and extrusion of PB was highest when the oocytes were matured in the medium supplemented with 10 μg/ml of KP. In experiment 2, oocytes were matured in 12 different maturation media (G1-G12: G1: Control, G2: KP alone, G3: FSH, G4: FSH+KP, G5: LH, G6: LH+KP, G7: E2, G8: E2+KP, G9: FSH+LH+E2, G10: FSH+LH+E2+KP, G11: FSH+LH+E2+fetal bovine serum (FBS), G12: FSH+LH+E2+FBS+KP). The proportion of oocytes showing cumulus expansion and PB extrusion was highest (98.33±1.05 and 89.17±2.38) when they were matured in FSH+LH+E2+FBS+KP (G12) and was significantly higher than other groups. The proportion of CCE and extrusion of PB was significantly increased when KP was supplemented to FSH and E2, but no effect was observed with LH. The maturation rates were significantly increased when FSH, LH, and E2 (G9) containing media were additionally supplemented with KP (G10). Conclusion: This study demonstrated that the addition of KP (10 μg/ml) to the FSH, LH, and E2 supplemented media would enhance the sheep oocyte maturation in vitro