The lesser-known Kumaon Meadow Blue Polyommatus dux Riley, 1926 (Lepidoptera: Lycaenidae: Polyommatinae: Polyommatini) from Uttarakhand, Western Himalaya

In spite of that Western Himalaya (Garhwal and Kumaon) geographically seems to be Oriental, the fauna of this high mountainous area has strong affinities with the Palaearctic region. The inner valleys of Kumaon Himalaya are close to Tibet, what is characterised by Sino-Himalayan xero-mountain elements, including the genus Polyommatus Latreille, 1804, one of the most diverse lycaenid genera in the Palaearctic region. In the Himalayas Polyommatus is represented by the diverse stoliczkanus species group. Here we report on Polyommatus dux Riley, 1926 from Kumaon Himalaya (type locality), what is an unusual member of the group displaying a hindwing ventral wingsurface with extensive structural colouration. Since the description the species has not been recorded. Therefore our finding is the second record since its discovery. On the basis of new material, the external habitus of the male is diagnosed and genitalia structures are described. Field observations are briefly recorded, imagines in nature are documented and the phenomena related to the butterfly wing surfaces are briefly discussed. The species is vulnerable to climate change driven range restriction and extinction threats, and thus considered as a candidate for flagship species for ecological studies in nature conservation investigations in the high-altitude region of the Kumaon Himalaya, Indi

Tailoring a Pt–Ru catalyst for enhanced methanol electro-oxidation

A carbon-supported (1:1) Pt–Ru (Pt–Ru/C) alloy catalyst has been prepared in-house by the sulfito-complex route, and has been tailored to achieve enhanced activity towards methanol electro-oxidation by annealing it at varying temperatures in air. The catalyst samples annealed between 250 and 300 ◦C in air for 30 min exhibit superior catalytic activity towards methanol electro-oxidation in a solid-polymer-electrolyte direct methanol fuel cell (SPE-DMFCs) operating at 90 ◦C. Both the as-prepared and annealed Pt–Ru/C catalysts have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and cyclic voltammetry. It is conjectured that while annealing the Pt–Ru/C catalysts, both Pt Pt and Pt Ru bonds increase whereas the Pt O bond shrinks. This is accompanied with a positive variation in Ru/Pt metal ratio suggesting the diffusion of Ru metal from the bulk catalyst to surface with an increase in oxidic ruthenium content. Such a treatment appears seminal for enhancing the electrochemical activity of Pt–Ru catalysts towards methanol oxidation

Synthesis and magnetic properties of nano-dimensional Fe1-xCuxAl2O4 (0.3 ≤ x ≤ 0.8)

Here we report, the sol-gel synthesized, microstructural analysis, surface and magnetic properties of solid solutions of Fe1-xCuxAl2O4. The singular phase of the samples for x values varied between 0.3 and 0.8 at 700 °C has been obtained. The powder X-ray diffraction, electron diffraction and HRTEM analysis reveal that the particle size systemically increases with the increase in x value. The XPS studies have confirmed the presence of Cu2+ species with a (Fe + Cu)/Al surface atomic ratio close to the bulk stoichiometric value. Unlike the common magnetic spinels with B-site magnetic cations, Fe1-xCuxAl2O4 shows only A-site magnetism in a diamond-type lattice. The samples with smaller particle size, namely the samples for x = 0.3 and 0.4 exhibit small magnetization. The origin of such magnetism is attributed to the inversion in the spinel structure and the defect induced magnetism. Except for the x = 0.7 sample, all other samples show spin glass behavior. © 2015 The Royal Society of Chemistry

Synthesis and magnetic properties of nano-dimensional Fe1-xCuxAl2O4 (0.3 ≤ x ≤ 0.8)

International audienceHere we report, the sol-gel synthesized, microstructural analysis, surface and magnetic properties of solid solutions of Fe1-xCuxAl2O4. The singular phase of the samples for x values varied between 0.3 and 0.8 at 700 °C has been obtained. The powder X-ray diffraction, electron diffraction and HRTEM analysis reveal that the particle size systemically increases with the increase in x value. The XPS studies have confirmed the presence of Cu2+ species with a (Fe + Cu)/Al surface atomic ratio close to the bulk stoichiometric value. Unlike the common magnetic spinels with B-site magnetic cations, Fe1-xCuxAl2O4 shows only A-site magnetism in a diamond-type lattice. The samples with smaller particle size, namely the samples for x = 0.3 and 0.4 exhibit small magnetization. The origin of such magnetism is attributed to the inversion in the spinel structure and the defect induced magnetism. Except for the x = 0.7 sample, all other samples show spin glass behavior. © 2015 The Royal Society of Chemistry

Synthesis, structure and magnetic properties of nanodimensional La1-xBaxFe0.5Mn0.5O3 perovskites

Here we report synthesis, structure and magnetic properties of low temperature synthesized nanodimensional La1-xBaxFe0.5Mn0.5O3 (x = 0.25, 0.33 and 0.50) perovskites. All the samples crystallize in cubic Pm-3m space group. The additional reflection spots (110) in electron diffraction (ED) requiring doubling of cubic cell parameter suggests the possible ordering of Fe and Mn in B-site. The magnetic property of the nanostructured samples is associated with the ferromagnetic clusters developed at the surface of nanoparticles. Such clusters disappeared subsequent to high temperature annealing. Importantly, unlike the homologous series La0.5Ca0.5Fe0.5Mn0.5O3 and La0.5Sr0.5Fe0.5Mn0.5O3 or electronically equivalent ferromagnetic LaFe0.5Cr0.5O3 (TC ∼ 120 K), La0.5Ba0.5Fe0.5Mn0.5O3 fails to exhibit any long range ordering. This curious observation can be better rationalized by considering the cationic size disorder parameter (σ2 = Σxiri 2 -andlt;rAandgt;2) in A-site rather than the random distribution of Fe and Mn in B-site. © 2018 Elsevier B.V

Synthesis, structure and magnetic properties of nanodimensional La1-xBaxFe0.5Mn0.5O3 perovskites

International audienceHere we report synthesis, structure and magnetic properties of low temperature synthesized nanodimensional La1-xBaxFe0.5Mn0.5O3 (x = 0.25, 0.33 and 0.50) perovskites. All the samples crystallize in cubic Pm-3m space group. The additional reflection spots (110) in electron diffraction (ED) requiring doubling of cubic cell parameter suggests the possible ordering of Fe and Mn in B-site. The magnetic property of the nanostructured samples is associated with the ferromagnetic clusters developed at the surface of nanoparticles. Such clusters disappeared subsequent to high temperature annealing. Importantly, unlike the homologous series La0.5Ca0.5Fe0.5Mn0.5O3 and La0.5Sr0.5Fe0.5Mn0.5O3 or electronically equivalent ferromagnetic LaFe0.5Cr0.5O3 (TC ∼ 120 K), La0.5Ba0.5Fe0.5Mn0.5O3 fails to exhibit any long range ordering. This curious observation can be better rationalized by considering the cationic size disorder parameter (σ2 = Σxiri 2 -andlt;rAandgt;2) in A-site rather than the random distribution of Fe and Mn in B-site. © 2018 Elsevier B.V