Substitution of Ca2+ in Calcite by Sn2+ and Sr2+ cations through ion exchange characterized by X-ray absorption and photoelectron spectroscopies

Tin (Sn2+) and strontium (Sr2+), two potential alternatives to lead (Pb2+) in perovskite formation, were explored in transforming calcium carbonate (CaCO3) into a leaving group in a cation exchange reaction. This is the first part of a sequential ion exchange process in transforming calcite into a Pb-free perovskite material for perovskite solar cell applications. Calcite, a polymorph of CaCO3, was successfully transformed into strontianite (SrCO3) through a cation exchange reaction. In the Sn substitution reaction on the other hand, no SnCO3 formation was noted. Instead, oxides of Sn were formed. The wider spaces in between Ca2+ cations in (100) orientation account for the higher atomic Sn2+ and Sr2+ concentrations as compared to (001) orientation, where the cation movement is restricted. X-ray absorption and photoelectron spectroscopies were used to investigate the ion-exchange transformation of calcite towards the formation of an intermediate carbonate material. Graphic abstract

THE USAGE OF ENGLISH COMMUNICATIVE VERBS IN SCIENTIFIC TECHNIAL PUBLICATIONS

In the article “The Usage of English Communicative Verbs in Scientific Technical Publications” communicative verbs of transmission, reception, exchange, transformation, storage and reproduction of information have been examined. It has been revealed peculiarities of communicative verbs typical usage for different scientific publications. The investigation of scientific publications has been corroborated the presence of five lexica-semantic communicative verbs groups.

Contribution of ion-exchange transformation of the adsorbed complex of atmospheric aerosols to the formation of seawater salt composition

Data on the total exchange capacity and composition of the adsorbed complex of terrigenous aerosols generated in arid and semiarid regions of the earth were summarized. It was calculated that as a result of change in composition of the adsorbed complex of aerosols occurring during their interaction with seawater, 2.64–4.86 million tons/year of dissolved Ca2+ are additionally enters into the ocean and 2.45–4.51, 0.73–1.34, and 0.08–0.14 million tons/year of dissolved Na+, K+, and Mg2+, respectively, are removed.

Derived sequences of complementary symmetric Rote sequences

Complementary symmetric Rote sequences are binary sequences which have factor complexity C(n) = 2n for all integers n ≥ 1 and whose languages are closed under the exchange of letters. These sequences are intimately linked to Sturmian sequences. Using this connection we investigate the return words and the derived sequences to the prefixes of any complementary symmetric Rote sequence v which is associated with a standard Sturmian sequence u. We show that any non-empty prefix of v has three return words. We prove that any derived sequence of v is coding of three interval exchange transformation and we determine the parameters of this transformation. We also prove that v is primitive substitutive if and only if u is primitive substitutive. Moreover, if the sequence u is a fixed point of a primitive morphism, then all derived sequences of v are also fixed by primitive morphisms. In that case we provide an algorithm for finding these fixing morphisms.

Cutting and Shuffling of a Line Segment: Effect of Variation in Cut Location

We present a computational study of the impact of variation in cut location on finite-time mixing of a line segment by cutting and shuffling, which is a one-dimensional piecewise isometry (PWI), also known as an interval exchange transformation (IET). A line segment of unit length is repeatedly cut into subsegments and shuffled according to any one of a variety of permutations. To mimic practical process error, variations drawn from a normal distribution are used to perturb cut locations. Illustrative examples of the mixing behaviors and finite-time measures of mixing are used to analyze the effect of variation in cut location for different permutations of subsegment mixing order. Mixing is significantly improved under irreducible nonrotational permutations when the dynamics show a resonance-like structure without variation. Specifically, the requirement of an irrational subsegment length ratio for good mixing can be relaxed as the underlying periodic dynamics is perturbed by the stochastic variation in cut location. Thus, good mixing can occur even with only four subsegments of roughly the same length for most irreducible nonrotational permutations.

Self-assembly of cobalt hexacyanoferrate crystals in 1-D array using ion exchange transformation route for enhanced electrocatalytic oxidation of alkaline and neutral water

1-D array of Co3[Fe(CN)6]2 film obtained by ion exchange mediated chemical transformation route from Co(CO3)0.35Cl0.20(OH)1.10 demonstrated an enhanced electrocatalytic oxidation of alkaline and neutral water.