Divergent karyotypes in five genera of the African endemic fish family Distichodontidae (Cithariniformes, Osteichthyes).

The African family Distichodontidae comprises 109 species in 16 genera. Up-to-date cytogenetic information was available for the only distichodontid species Distichodusaffinis Günther, 1873. Here we report chromosome number and morphology in: Distichodusengycephalus Günther, 1864 (2n = 52, FN = 104), Ichthyborusbesse (Joannis, 1835) (2n = 46, FN = 92), Nannocharaxniloticus (Joannis, 1835) (2n = 54, FN = 106) and three taxa, Nannaethiopsbleheri Géry et Zarske, 2003, Nannaethiops sp., and Neolebiasunifasciatus Steindachner, 1894, that exhibit the same karyotypes (2n = 50, FN = 98). To confirm the Nannaethiops Günther, 1872 and Neolebias Steindachner, 1894 species identification, mt-DNA sequences of the two markers (COI and 16S rRNA) were obtained from karyotyped specimens and compared with the relevant sequences accessible from GenBank. The great prevalence of biarmed chromosomes (the karyotypes of most species contain exclusively biarmed chromosomes) is a distinctive characteristic of Distichodontidae and Cithariniformes as a whole.

Towards sustainable electrochemistry: green synthesis and sintering aid modulations in the development of BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) IT-SOFC electrolytes.

In this study, BaZr0.87Y0.1M0.03O3-δ perovskite electrolytes with sintering aids (M = Mn, Co, and Fe) were synthesized by a sustainable approach using spinach powder as a chelating agent and then compared with chemically synthesized BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes for intermediate temperature SOFCs. This is the first example of such a sustainable synthesis of perovskite materials with sintering aids. Structural analysis revealed the presence of a cubic perovskite structure in BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) samples synthesized by both green and conventional chemical methods. No significant secondary phases were observed in the samples synthesized by a sustainable approach. The observed phenomena of plane shift were because of the disparities between ionic radii of the dopants, impurities, and host materials. The surface morphology analysis revealed a denser microstructure for the electrolytes synthesized via green routes due to metallic impurities in the organic chelating agent. The absence of significant impurities was also observed by compositional analysis, while functional groups were identified through Fourier-transform infrared spectroscopy. Conductivity measurements showed that BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes synthesized by oxalic acid have higher conductivities compared to BaZr0.87Y0.1M0.03O3-δ (M = Mn, Co, and Fe) electrolytes synthesized by the green approach. The button cells employing BaZr0.87Y0.1Co0.03O3-δ electrolytes synthesized by the chemical and green routes achieved peak power densities 344 and 271 mW·cm-2 respectively, suggesting that the novel green route can be applied to synthesize SOFC perovskite materials with minimal environmental impact and without significantly compromising cell performance.

Modernized Synthesis Technique of Pr2NiO4+δ-Based Complex Oxides Using Low-Temperature Salt Melts.

Phases based on layered lanthanide nickelates are considered as promising electrode materials for various electrochemical devices, including solid oxide fuel cells and electrolysis cells. While such compounds may be prepared using either solid state or solution-assisted syntheses, each of these approaches entails certain problems. In the present work, we propose a novel approach for the simple and straightforward preparation of Pr2NiO4+δ-based materials. This approach involves co-melting of initial nitrate components, followed by high-temperature decomposition of the obtained mixture. The developed synthesis method exhibits a number of advantages over conventional techniques, enabling highly dispersed and single-phase powders to be obtained at a reduced synthesis temperature of 1050 °C. Therefore, the results of this work open new possibilities for the cost-effective preparation of Ruddlesden-Popper oxide phases.

First cytogenetic data on Afrotropical lutefishes (Citharinidae) in the light of karyotype evolution in Characiformes.

The Afrotropical lutefish family Citharinidae (Citharinoidei, Characiformes) comprises three genera with eight species in total. Although Citharinidae have been studied in terms of taxonomy and systematics, no cytogenetic information was available for any representative of the family. Furthermore, only one species out of 116 in Citharinoidei (Distichodusaffinis Günther, 1873) has been studied cytogenetically. Here, we report the karyotypes of Citharinuscitharus (Geoffroy St. Hilaire, 1809) from West Africa and Citharinuslatus Müller et Troschel, 1844 from Northeast Africa. The former has the diploid chromosome number 2n = 40 and the fundamental number FN = 80, while the latter has 2n = 44 and FN = 88. Hence, these karyotypes consist exclusively of bi-armed chromosomes. Such karyotypes were previously found in D.affinis and in many lineages of Neotropical species of another suborder of Characiformes, Characoidei. In contrast, the karyotypes dominated by uni-armed elements are typical for a number of phylogenetically basal lineages of Afrotropical and Neotropical Characoidei. We discuss the importance of our data on Citharinidae for the understanding of the karyotype evolution within the order Characiformes.

Nickel-Containing Perovskites, PrNi0.4Fe0.6O3-δ and PrNi0.4Co0.6O3-δ, as Potential Electrodes for Protonic Ceramic Electrochemical Cells.

Protonic ceramic fuel cells (PCFCs) offer a convenient means of converting chemical energy into electricity with high performance and efficiency at low- and intermediate-temperature ranges. However, in order to ensure good life-time stability of PCFCs, it is necessary to ensure rational chemical design in functional materials. Within the present work, we propose new Ni-based perovskite phases of PrNi0.4M0.6O3-δ (where M = Co, Fe) for potential utilization in protonic ceramic electrochemical cells. Along with their successful synthesis, functional properties of the PrNi0.4M0.6O3-δ materials, such as chemical compatibility with a number of oxygen-ionic and proton-conducting electrolytes, thermal expansion behavior, electrical conductivity, and electrochemical behavior, were comprehensively studied. According to the obtained data, the Co-containing nickelate exhibits excellent conductivity and polarization behavior; on the other hand, it demonstrates a high reactivity with all studied electrolytes along with elevated thermal expansion coefficients. Conversely, while the iron-based nickelate had superior chemical and thermal compatibility, its transport characteristics were 2-5 times worse. Although, PrNi0.4Co0.6O3-δ and PrNi0.4Fe0.6O3-δ represent some disadvantages, this work provides a promising pathway for further improvement of Ni-based perovskite electrodes.

Layered Oxygen-Deficient Double Perovskites as Promising Cathode Materials for Solid Oxide Fuel Cells.

Development of new functional materials with improved characteristics for solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) is one of the most important tasks of modern materials science. High electrocatalytic activity in oxygen reduction reactions (ORR), chemical and thermomechanical compatibility with solid electrolytes, as well as stability at elevated temperatures are the most important requirements for cathode materials utilized in SOFCs. Layered oxygen-deficient double perovskites possess the complex of the above-mentioned properties, being one of the most promising cathode materials operating at intermediate temperatures. The present review summarizes the data available in the literature concerning crystal structure, thermal, electrotransport-related, and other functional properties (including electrochemical performance in ORR) of these materials. The main emphasis is placed on the state-of-art approaches to improving the functional characteristics of these complex oxides.

Thermal lattice Boltzmann method for multiphase flows.

An alternative method to simulate heat transport in the multiphase lattice Boltzmann (LB) method is proposed. To solve the energy transport equation when phase boundaries are present, the method of a passive scalar is considerably modified. The internal energy is represented by an additional set of distribution functions, which evolve according to an LB-like equation simulating the transport of a passive scalar. Parasitic heat diffusion near boundaries with a large density gradient is suppressed by using special "pseudoforces" which prevent the spreading of energy. The compression work and heat diffusion are calculated by finite differences. A new method to take into account the latent heat of a phase transition Q(T) is realized. The latent heat is released or absorbed continuously inside a thin transition layer in a certain range of density, ρ_{1}<ρ<ρ_{2}. This allows one to avoid interface tracking. Several tests were carried out concerning all aspects of the processes. It is shown that the Galilean invariance and the scaling of the thermal conduction process hold, as well as the correct dependence of the sound speed on the heat capacity ratio. The method proposed has low scheme diffusion of the internal energy, and it can be applied to modeling a wide range of multiphase flows with heat and mass transfer even for high density ratios of liquid and vapor phases.

Description of a new species of the genus Protracheoniscus Verhoeff, 1917 and redescription of Protracheoniscuskryszanovskii Borutzky, 1957 from the southeast of European Russia (Isopoda, Oniscidea, Agnaridae).

A new species of woodlice, Protracheoniscuspokarzhevskii Gongalsky & Turbanov, sp. n. is described from Kalmykia, NE Pre-Caspian region, Russia. Protracheoniscuskryszanovskii Borutzky, 1957 from the same area is also redescribed. Diagnostic features of these species as well as affinities within the genus are provided and discussed.

Anisotropic instability of a dielectric liquid in a strong uniform electric field: Decay into a two-phase system of vapor filaments in a liquid.

The linear stability analysis of dielectric liquid placed in uniform electric field with respect to perturbations of density of an initially uniform state was carried out. The electric field increases the instability increment for the stratification along the field and decreases it for the transversal stratification. Thus, anisotropic separation into liquid and vapor phases is possible in high electric fields for a liquid that is initially in unstable state, as well as in metastable or stable states. Computer simulations of electrohydrodynamics confirm the theoretical calculations. It is important that new regions of low density phase appear as narrow cylindrical channels oriented along the field. This mechanism of generation of gaseous phase in locally high electric field can play a key role in processes of inception and ultrafast propagation of streamers during breakdown of liquid dielectrics in nanosecond range.