Electrocatalytic Oxygen Reduction Reaction at Silver Nanoparticles (AgNPs) Electrode in Neutral Solution: 5-amino- 2-naphthalene-sulfonic acid (ANS) as a Reducing Agent for AgNPs

We report electrocatalytic oxygen reduction reaction (ORR) at silver nanoparticle (AgNPs) electrodes. The AgNPs was obtained in a general one-pot synthesis using 5-amino 2-naphthalene-sulfonic acid (ANS) as a reducing agent in aqueous and room-temperature conditions. The simultaneous formation of AgNPs and an oxidation of ANS were monitored by UV-vis spectroscopy. Surface morphology of AgNPs was characterized by transmission electron microscopy, which revealed that AgNPs appeared as a sphere. The average size of AgNPs was found to be 162 nm. Furthermore, the chemical identity of the nanostructures was established using X-ray photoelectron spectroscopy and X-ray diffraction. The prepared AgNPs showed electrocatalytic activity for reduction of oxygen in neutral pH. Rotating disk electrode voltammetry was used to elucidate kinetics of ORR at AgNPs electrode. These results reveal that oxygen reduction reaction at AgNPs-PANS electrode involved direct four electron pathways.

Geochemical heterogeneity of polychronous relict zircons from restitogenic ultramafic rocks of the Shaman massif (Eastern Transbaikal region)

Research subject. The distribution patterns of rare earth elements (REE), as well as Y and Th, in the grains of polychromous zircons from the restitogenic ultramafic rocks of the Shaman massif (Eastern Transbaikalia). This massif is a steeply inclined protrusion that is part of the eastern branch of the Baikal-Muya ophiolite belt.Materials and methods. 31 zircon grains 100–150 μm in size were isolated from a composite sample of harzburgites and dunites with a total weight of 4 kg for their subsequent U-Pb isotope dating. These analyzes were performed by the LA-ICP-MS method by scanning along straight profiles on the plane of sections of representative zircon grains.Results. All zircon grains from the general collection are characterized by a rounded shape, a rough surface, microfracturing, a weak cathodoluminescent glow to a complete absence, and an irregular oscillatory zoning. In some grains, microinclusions of epigenetic minerals, such as quartz, mica, etc. were found. It was previously determined that, within the entire collection of zircon grains, the values of their age, as well as U and Th contents, vary across rather wide intervals (3049–502 Ma), the reasons for which are the subject of discussions. The LA-ICP-MS scanning over the profiles of representative zircon grains from the general collection showed that REE, Th, and Y are distributed highly unevenly, occasionally showing signs of zoning. It is assumed that the zircons found in the ultramafic rocks of this massif are a relict phase and appeared as a result of the transformation of very ancient (more than 3 billion years old) juvenile crystals of this mineral, which had been originally located in the upper mantle protolith.Conclusions. Transformations of juvenile zircons and their transformation into a relict phase occurred in the process of partial melting of the protolith, during which they underwent thermal action (annealing), chemical resorption, as well as disturbances in their U-Pb systems, which caused uneven “rejuvenation” of their isotopic age. It is also assumed that the revealed geochemical heterogeneity of relict zircons was mainly due to the later redistribution of trace elements with the simultaneous formation of microinclusions of epigenetic minerals in the process of infiltration along microcracks into ultramafic rocks, precipitated by acidic melts.

Recent results from deuterium experiments on the Large Helical Device and their contribution to fusion reactor development

In recent deuterium experiments on the Large Helical Device (LHD), we succeeded in expanding the temperature domain to higher regions for both electron and ion temperatures. Suppression of the Energetic particle driven resistive InterChange mode (EIC) by a moderate electron temperature increase is a key technique to extend the high temperature domain of LHD plasmas. We found a clear isotope effect in the formation of the Internal Transport Barrier (ITB) in high temperature plasmas. A new technique to measure the hydrogen isotope fraction was developed in the LHD in order to investigate the behavior of the isotope mixing state. The technique revealed that the non-mixing and the mixing states of hydrogen isotopes can be realized in plasmas. In deuterium plasmas, we also succeeded simultaneously realizing the formation of the Edge Transport Barrier (ETB) and the divertor detachment. It is found that Resonant Magnetic Perturbation (RMP) plays an important role in the simultaneous formation of the ETB and the detachment. Contributions to fusion reactor development from the engineering point of view, i.e. Negative-ion based Neutral Beam Injector (N-NBI) research and the mass balance study of tritium, are also discussed

The basic architecture of mobile robotic platform with intelligent motion control system and data transmission protection

The requirements for a mobile robotic platform (MRP) with an intelligent traffic control system and data transmission protection are determined. Main requirements are the reduction of dimensions, energy consumption, and cost; remote and intelligent autonomous traffic control; real-time cryptographic data protection; preservation of working capacity in the conditions of action of external factors; adaptation to customer requirements; ability to perform tasks independently in conditions of uncertainty of the external environment. It is proposed to develop a mobile robotic platform based on an integrated approach including: navigation methods, methods of pre-processing and image recognition; modern methods and algorithms of intelligent control, artificial neural networks, and fuzzy logic; neuro-like methods of cryptographic data transmission protection; modern components and modern element base; methods of intellectual processing and evaluation of data from sensors in the conditions of interference and incomplete information; methods and means of automated design of MRP hardware and software. The following principles were chosen for the development of a mobile robotic platform with an intelligent control system and cryptographic protection of data transmission: hierarchical construction of an intelligent control system; systematicity; variable composition of equipment; modularity; software openness; compatibility; specialization and adaptation of hardware and software to the structure of algorithms for data processing and protection; use of a set of basic design solutions. The basic architecture of a mobile robotic platform with an intelligent traffic control system and data transmission protection has been developed, which is the basis for the construction of mobile robotic platforms with specified technical and operational parameters. To implement neuro-like tools, the method of tabular-algorithmic calculation of the scalar product was improved, which due to the simultaneous formation of k macroparticle products provides k times reduction of the time of the scalar product calculation. Keywords: mobile robotic platform; intelligent processing; architecture; neural network; autonomous control; sensors; data protection.

Daughter centrioles assemble preferentially towards the nuclear envelope in Drosophila syncytial embryos

Centrosomes are important organisers of microtubules within animal cells. They comprise a pair of centrioles surrounded by the pericentriolar material (PCM), which nucleates and organises the microtubules. To maintain centrosome numbers, centrioles must duplicate once and only once per cell cycle. During S-phase, a single new daughter centriole is built orthogonally on one side of each radially symmetric mother centriole. Mis-regulation of duplication can result in the simultaneous formation of multiple daughter centrioles around a single mother centriole, leading to centrosome amplification, a hallmark of cancer. It remains unclear how a single duplication site is established. It also remains unknown whether this site is pre-defined or randomly positioned around the mother centriole. Here, we show that within Drosophila syncytial embryos daughter centrioles preferentially assemble on the side of the mother facing the nuclear envelope, to which the centrosomes are closely attached. This positional preference is established early during duplication and remains stable throughout daughter centriole assembly, but is lost in centrosomes forced to lose their connection to the nuclear envelope. This shows that non-centrosomal cues influence centriole duplication and raises the possibility that these external cues could help establish a single duplication site.

Prebiotic Synthesis of α-Amino Acids and Orotate from α-Ketoacids Potentiates Transition to Extant Metabolic Pathways

The Strecker reaction of aldehydes is the preeminent pathway to explain the prebiotic origins of a-amino acids. However, biology employs transamination of a-ketoacids to give rise to amino acids which are then transformed to nucleobases, implying subsequent evolution of the biosynthetic pathways – abiotically or biotically. Herein, we show that a-ketoacids react with cyanide and ammonia sources to form the corresponding a-amino acids – via the Bucherer-Bergs pathway. An efficient prebiotic transformation of oxaloacetate to aspartate via N-carbamoyl aspartate enables the simultaneous formation of dihydroorotate, paralleling the biochemical synthesis of orotate as the precursor to pyrimidine nucleobases. Glyoxylate forms both glycine and orotate, and reacts with malonate and urea to form aspartate and dihydroorotate. These results, along with the previously demonstrated protometabolic analogs of the Krebs cycle suggest that there can be a natural emergence of congruent forerunners of biological pathways with the potential for seamless transition from prebiotic chemistry to modern metabolism.

Effect of high-temperature oxidation on the surface properties as applied to quenching of high-temperature bodies

This paper contains the results of studying the surface properties before and after high-temperature oxidation. For this, the plate zirconium samples with chromium, gold and silver coatings were prepared. Cut profiles of the samples were obtained to study the structure of coatings and the thickness of the oxide layer. The measurements of contact angles were carried out. The results showed that a porous heterogeneous oxide layer was formed on the samples after high-temperature oxidation. At the same time, the wettability of the samples was improved. The thickness of the oxide layer on the chrome-coated zirconium sample was the smallest. Using of electroplated silver coating for experiments involving heating to high temperatures seems inappropriate because it was damaged after the oxidation tests. It is assumed that the main factor which influence on the rise of the transition temperature to the intensive cooling regime during quenching is the appearance of the oxide layer, rather than the improved wettability and wickability. High-temperature oxidation leads to the simultaneous formation of an oxide layer with a low thermal effusivity and to an improvement in wettability, therefore the contribution of each of these two effects on quenching can be confused or overestimated.

Insights on the Electrocatalytic Seawater Splitting at Heterogeneous Nickel-Cobalt Based Electrocatalysts Engineered from Oxidative Aniline Polymerization and Calcination

Given the limited access to freshwater compared to seawater, a growing interest surrounds the direct seawater electrolysis to produce hydrogen. However, we currently lack efficient electrocatalysts to selectively perform the oxygen evolution reaction (OER) over the oxidation of the chloride ions that are the main components of seawater. In this contribution, we report an engineering strategy to synthesize heterogeneous electrocatalysts by the simultaneous formation of separate chalcogenides of nickel (NiSx, x = 0, 2/3, 8/9, and 4/3) and cobalt (CoSx, x = 0 and 8/9) onto a carbon-nitrogen-sulfur nanostructured network. Specifically, the oxidative aniline polymerization in the presence of metallic cations was combined with the calcination to regulate the separate formation of various self-supported phases in order to target the multifunctional applicability as both hydrogen evolution reaction (HER) and OER in a simulated alkaline seawater. The OER’s metric current densities of 10 and 100 mA cm−2 were achieved at the bimetallic for only 1.60 and 1.63 VRHE, respectively. This high-performance was maintained in the electrolysis with a starting voltage of 1.6 V and satisfactory stability at 100 mA over 17 h. Our findings validate a high selectivity for OER of ~100%, which outperforms the previously reported data of 87–95%.