3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles during oxygen evolution reaction

The three-dimensional (3D) distribution of individual atoms on the surface of catalyst nanoparticles plays a vital role in their activity and stability. Optimising the performance of electrocatalysts requires atomic-scale information, but it is difficult to obtain. Here, we use atom probe tomography to elucidate the 3D structure of 10 nm sized Co2FeO4 and CoFe2O4 nanoparticles during oxygen evolution reaction (OER). We reveal nanoscale spinodal decomposition in pristine Co2FeO4. The interfaces of Co-rich and Fe-rich nanodomains of Co2FeO4 become trapping sites for hydroxyl groups, contributing to a higher OER activity compared to that of CoFe2O4. However, the activity of Co2FeO4 drops considerably due to concurrent irreversible transformation towards CoIVO2 and pronounced Fe dissolution. In contrast, there is negligible elemental redistribution for CoFe2O4 after OER, except for surface structural transformation towards (FeIII, CoIII)2O3. Overall, our study provides a unique 3D compositional distribution of mixed Co-Fe spinel oxides, which gives atomic-scale insights into active sites and the deactivation of electrocatalysts during OER.

CALCULATION OF THE CONSTANTS OF COPOLYMERIZATION OF METHACRYLAMIDE WITHN-VINYLCAPROLACTAM

In this work, a copolymer of methacrylamide with N-vinylcaprolactam was synthesized for the first time by the method of radical copolymerization, based on the obtained values of the copolymerization constants, the dependence of the instantaneous and average composition of the copolymer was calculated. The relative activity constants r1 and r2 of methacrylamide and N-vinylcaprolactam monomers in the reaction of radical copolymerization have been calculated. The probability of the formation of different sequences of units during the formation of the copolymer was investigated. The variance of the compositional distribution was found to have a minimum at the azeatropic point.Key words:copolymerization, methacrylamide, N-vinylcaprolactam, monomer, copolymer, instant composition, average composition, modification, compositional heterogeneity, dispersion

Control of the size and compositional distributions in a milling process by using a reverse breakage matrix approach

A method based on the reverse breakage matrix approach is proposed for controlling the effects that milling has on the particle size distribution and composition of the comminuted material. Applicability, possibilities, and limitations of the proposed method are tested on examples related to the process of wheat flour milling. It has been shown that the reverse matrix approach can be successfully used for defining the particle size distribution of the input material leading to the desired, predetermined particle size and compositional distribution in the output material. Moreover, we have illustrated that it is possible to simultaneously control both, input and output particle size distribution, together with the composition of the output material.

Structural and compositional characteristics of Fukushima release particulate material from Units 1 and 3 elucidates release mechanisms, accident chronology and future decommissioning strategy

The structural form and elemental distribution of material originating from different Fukushima Daiichi Nuclear Power Plant reactors (Units 1 and 3) is hereby examined to elucidate their contrasting release dynamics and the current in-reactor conditions to influence future decommissioning challenges. Complimentary computed X-ray absorption tomography and X-ray fluorescence data show that the two suites of Si-based material sourced from the different reactor Units have contrasting internal structure and compositional distribution. The known event and condition chronology correlate with the observed internal and external structures of the particulates examined, which suggest that Unit 1 ejecta material sustained a greater degree of melting than that likely derived from reactor Unit 3. In particular, we attribute the near-spherical shape of Unit 1 ejecta and their internal voids to there being sufficient time for surface tension to round these objects before the hot (and so relatively low viscosity) silicate melt cooled to form glass. In contrast, a more complex internal form associated with the sub-mm particulates invoked to originate from Unit 3 suggest a lower peak temperature, over a longer duration. Using volcanic analogues, we consider the structural form of this material and how it relates to its environmental particulate stability and the bulk removal of residual materials from the damaged reactors. We conclude that the brittle and angular Unit 3 particulate are more susceptible to further fragmentation and particulate generation hazard than the round, higher-strength, more homogenous Unit 1 material.

Formation Mechanism of Dilute Region and Microstructure Evolution in Laser Solid Forming TA15/Ti2AlNb Dual Alloy

TA15/Ti2AlNb multiple-layer samples and a dual-alloy sample were fabricated by laser solid forming (LSF) in this study. The formation mechanism of the dilute region and microstructure evolution of the dual alloy were analyzed. The results confirmed a “step” distribution of the composition among several initial layers in the multiple-layer samples, which can be explained by calculating the ratio of the remelted zone to the deposited Ti2AlNb zone in each deposited layer. However, the “step” compositional distribution disappears, and the compositional variation tends to be more continuous and smooth in the TA15/Ti2AlNb dual-alloy sample, which is attributed to alloy elements’ diffusion at the subsequent multiple re-melting and the longer thermal cycle. The macrostructure of the TA15/Ti2AlNb dual-alloy sample consists of epitaxially grown columnar prior β grains at the TA15 side and equiaxed grains at the Ti2AlNb side, while the microstructure shows a transition of α+β→α+α2+β/B2→α2+β/B2→α2+B2+O with increasing amounts of Ti2AlNb, leading to the microhardness also changing significantly.

The Motif of Journey in Kunwar Narain’s Poetry

The article is focused on the motif of a journey in the works of a modern Indian poet, Kunwar Narain, a representative of New Hindi poetry. This motif of a journey is extremely important in Indology studies. Starting with the Indian epic poems “Mahabharata” and “Ramayana”, the motif of pilgrimage has been one of the significant plot lines. During the Medieval period, the motif of a journey became an allegory of individuality cognition. In modern Hindi literature writers introduce innovation in the image of travel, remaining within the established Indian tradition. The research in this article is based on the bilingual collection of poems by Kunwar Narain “No other world”. The article argues that a journey becomes the leitmotif in the poet’s lyrics. As a result, the Indian poet writes a kind of a travel literature, which is based on the image of the way with two semantic motives: a journey as a hero’s movement in space and a hero’s search for his essence, including a peculiar path as an allegory of his spiritual formation. The article focuses on the compositional distribution of poems in the “Journey” section of the book. This distribution expresses the movement of the author’s thoughts. The analysis of the literary techniques, symbolic images and allusions was conducted in the frames of not only Indian literature, but also American poet Walt Whitman’s creations, which had a great influence on Kunwar Narain’s lyrics. Literary influences are identified that contributed to the formation of the Indian poet’s worldview.

Checked patterned elemental distribution in AlGaAs nanowire branches via vapor–liquid–solid growth

Ga-rich stripes parallel to the growth direction of AlGaAs nanowire branches intersect with a periodic arrangement of Ga-rich stripes perpendicular to them, leading to the realization of a checked pattern of compositional distribution.