Double-Exchange Magnetic Interactions in High-Temperature Ferromagnetic Iron Chalcogenide Monolayers.

Smythite ( F e 3 S 4 ) is an iron-based chalcogenide with a lamellar structure, different from the compositionally identical mineral greigite. Owing to their natural abundance, such transition metal chalcogenides are promising materials for low-cost spintronic-based devices. Herein, we discuss the charge transfer processes and complex magnetic ordering in a two-dimensional (2D) smythite lattice. We find that F e 2 + / F e 3 + redox couple and complex magnetic ordering are governing factors in the charge transfer processes. A very strong ferromagnetic in-lattice coupling is also observed, which is attributed to the presence of three Fe-centres. To describe the magnetic behaviour molecular and periodic approaches have been considered. We found a substantial increase in Curie temperature with applied mechanical stress due to opening of the double exchange interaction angle. We also observe an in-plane Jahn-Teller distortion, which is further confirmed by the spin-orbit counter plot. Our study thus provides an insight into the double exchange mechanism favoured by the F e 2 + / F e 3 + redox couple and results in a strong ferromagnetic ordering.

Emergence of Topological insulator and Nodal line semi-metal states in XX'Bi (X = Na, K, Rb, Cs; X' = Ca, Sr).

In this article, we predict the emergence of non-trivial band topology in the family of XX'Bi compounds having [Formula: see text] (# 189) space group. Using first principles calculations within hybrid functional framework, we demonstrate that NaSrBi and NaCaBi are strong topological insulator under controlled band engineering. Here, we propose three different ways to engineer the band topology to get a non-trivial order: (i) hydrostatic pressure, (ii) biaxial strain (due to epitaxial mismatch), and (iii) doping. Non-triviality is confirmed by investigating bulk band inversion, topological Z2 invariant, surface dispersion and spin texture. Interestingly, some of these compounds also show a three dimensional topological nodal line semi-metal (NLS) state in the absence of spin orbit coupling (SOC). In these NLS phases, the closed loop of band degeneracy in the Brillouin zone lie close to the Fermi level. Moreover, a drumhead like flat surface state is observed on projecting the bulk state on the [001] surface. The inclusion of SOC opens up a small band gap making them behave like a topological insulator.

Goitrogenic/antithyroidal potential of moringa leaves (Moringa oleifera) and spinach (Spinacia oleracea) of Indian origin on thyroid status in male albino rats

Moringa leaves and spinach used as vegetables containing cyanogens and polyphenols having suspected antithyroidal activity; however, detailed studies in this aspect found unavailable. Goitrogenic/antithyroid potentiality of those plant foods of Indian origin was evaluated. To explore the goitrogenic/antithyroid effect of those plant foods cyanogenic glucosides, glucosinolates, thiocyanate and polyphenol content were measured. These plant foods were fed with diet regularly to adult male albino rats for 30 and 60 days respectively, followed by evaluation of morphological and functional status of thyroid,as thyroid gland weight, the activity status of thyroid hormone synthesizing enzymes viz. TPO, Na+-K+-ATPase, deiodinase I, thyroid hormone profiles, thyroid histoarchitecture as well as urinary iodine and thiocyanate. In moringa leaves and spinach fed diet, there was a significant increase in urinary excretion of thiocyanate and iodine, enlargement of thyroid gland along with hypertrophy of thyroid follicles and altered in the activities of thyroid hormone synthesizing enzymes with concomitant changes of thyroid hormone profiles. Effects were more severe in moringa leaves treated group than that of spinach. Biochemical analysis moringa leaves and spinach reveal that those are rich sources of goitrogens and their prolonged consumption gradually developed a relative state of biochemical and morphological hypothyroidism.

Effect of Excess Iodine on Oxidative Stress Markers, Steroidogenic-Enzyme Activities, Testicular Morphology, and Functions in Adult Male Rats.

Improper iodine intake is a major concern in public health. Chronic intake of low iodine affects gonadal functions of man and animals; however, such effects of excess iodine in male reproduction, specially on testicular morphology, testicular steroidogenic enzyme activities, sperm morphology, sperm viability, and sperm count including male hormonal profiles in reference to iodine status and thyroid hormone profiles are yet to be explored. With this background, adult male rats of 120 ± 10 gm Bw of 90 ± 5 days were divided broadly in two groups depending on the duration of the treatment for 30 and 60 days, respectively. Both the groups consisted of control animals. Excess iodine (100EI), i.e., 100 times more than its recommended level but within its tolerable ranges, was administered through gavage regularly to the first group of experimental animals for 30 and 60 days, respectively, and excessive iodine (500EI), i.e., 500 times more than its recommended level and above tolerable range in the same way and for the same durations, was administered to the other group of experimental animals. Overall results revealed that regular consumption of iodine in excess impairs reproductive functions in adult male rats depending on the dose and duration of its exposure through different mechanisms. Excess iodine accumulates in the testis which results in generation of reactive oxygen species (ROS) as evidenced by higher lipid peroxidation level as well as an imbalance in the pro-/antioxidant status inhibiting the activity of ∆(5) 3ß- hydroxysteroid dehydrogenase (HSD) and 17ß-HSD resulting to reduced synthesis of testosterone that causes structural and functional changes of the testis. Secondly, persistent generation of ROS in testis as a result of prolonged excess iodine exposure affects hypothalamo-pituitary-adrenal axis that stimulates synthesis and secretion of corticosterone which inhibits LH release that downregulates testosterone synthesis causing further testicular disruption. Thirdly, excess iodine when administered above its tolerable ranges for prolonged duration acts on thyroid itself developing a state of biochemical hypothyroidism (as evident by low T3) which further potentiate the disrupting effect of excess iodine on male gonads by reducing circulating testosterone level.

Synergic actions of polyphenols and cyanogens of peanut seed coat (Arachis hypogaea) on cytological, biochemical and functional changes in thyroid.

In animals, long-term feeding with peanut (Arachis hypogaea) seed coats causes hypertrophy and hyperplasia of the thyroid gland. However, to date there have been no detailed studies. Here, we explored the thyroidal effects of dietary peanut seed coats (PSC) in rats. The PSC has high levels of pro-goitrogenic substances including phenolic and other cyanogenic constituents. The PSC was mixed with a standard diet and fed to rats for 30 and 60 days, respectively. Animals fed with the PSC-supplemented diet showed a significant increase in urinary excretion of thiocyanate and iodine, thyroid enlargement, and hypertrophy and/or hyperplasia of thyroid follicles. In addition, there was inhibition of thyroid peroxidase (TPO) activity, 5'-deiodinase-I (DIO1) activity, and (Na+-K+)-ATPase activity in the experimental groups of rats as compared to controls. Furthermore, the PSC fed animals exhibited decreased serum circulating total T4 and T3 levels, severe in the group treated for longer duration. These data indicate that PSC could be a novel disruptor of thyroid function, due to synergistic actions of phenolic as well as cyanogenic constituents.