Corrosion resistance of sulfated cements in carbonate and in carbonate-sulfate mediums

Corrosion resistance of sulfated cements in carbonate and in carbonate-sulfate mediums has been studied. The samples have been placed in carbonate and carbonate-sulfate mediums for investigation stability of sulfated cements. The same researches were done with sulfate resistant portland cement to compare stability of samples. High corrosive resistant of sulfated cements is conditioned by forming dense and strong cement stone. The obtaining of corrosion resistant cements is possible with usage of the ordinary portland cement clinker with inclusion to them sulfoferrite and sulfoalumoferrite clinkers. Sulfated cements have the higher corrosion stability in contrast to ordinary sulfate resistant cement

Flows of real gas in nozzles with unsteady local energy supply

When gas flows at a high speed in a channel with a variable cross sectional area and high-intensity energy supply, it experiences complicated physical and chemical processes producing high-temperature gas effects. High-temperature gas effects are a key issue related to design and optimization of nozzles of plasmatron of alternating current. The finite volume method is applied to solve unsteady compressible Euler equations with high-temperature gas effects. Solutions of some benchmark test cases are reported, and comparison between computational results of chemically equilibrium and perfect air flowfields is performed. The results of numerical simulation of one-dimensional and two-dimensional under- and over-expanded nozzle flows with a moving region of energy supply are presented. Output nozzle parameters are calculated as functions of a number and time of burning of plasmatron arcs. The results obtained show a qualitative pattern of gas dynamics and thermal processes in the nozzle with unsteady energy supply demonstrating the displacement of the nozzle shock wave towards the nozzle outlet in the over-expanded nozzle flow in comparison to perfect gas flow

Combination of processes and combined solutions in improving the technique and technology of arc welding and fusion

In work systematized and considered on the row of examples basic types of combinations of influences and combination of processes which are developed for the use in the arc welding and naplavke a fluxible electrode. It is shown that new technical and technological effects at welding and naplavke can be got only at purposeful introduction to the technological process of additional influence

ИССЛЕДОВАНИЕ ИЗНАШИВАНИЯ СТАЛЕЙ ПРИ НИЗКИХ СКОРОСТЯХ СКОЛЬЖЕНИЯ ПО АБРАЗИВУ

The abrasive wear tests with sliding speed in the range of 0,1–86,0 mm/s is fulfilled for carbon steels with different structure. It is found that the reduction of sliding speed from tens mm/sec to a few millimeters per second has different influence upon wear of the samples with different type of structure. The most significant increase of wear is attributed to the samples with ferritic structure. When the sliding speed decreases from 86,0 to 5 mm/sec, the mass loss of ferritic samples increases by 10 %. The effect of reducing sliding speed upon the wear of the samples with the structure of martensite and austenite is found to be not so significant. Проведены испытания нелегированных сталей в различном структурном состоянии в диапазоне скоростей скольжения по абразиву 0,1–86 мм/с. Установлено, что снижение скорости скольжения с десятков до единиц миллиметров в секунду по-разному влияет на износ образцов с различным типом структуры. Наиболее существенно увеличивается износ образцов со структурой феррита. При уменьшении скорости скольжения с 86 до 5 мм/с потеря массы ферритных образцов возрастает на 10 %. Влияние снижения скорости на износ образцов со структурой мартенсита и аустенита не столь значительно.

Влияние мартенсита на кинетику бейнитного превращения в сталях 60С2ХФА и 55С3Г2ХФМБА

The effect of cooling below Ms point (up to 160 °С and 200 °С) on the kinetics of bainite transformation in steels 60Si2CrVА and 55Si3Mn2CrVMoNb at isothermal exposure in the range of 225–350 °С is described. It is shown that, in most cases, the appearance of martensite accelerates the beginning of transformation, but leads to a slowing its completion or early delay due to the stabilization of austeniteОписано влияние подстуживания ниже точки Мн (до 160°С и 200 °С) на кинетику бейнитного превращения в сталях 60С2ХФА и 55С3Г2ХФМБА при изотермической выдержке в диапазоне 225–350 °С. Показано, что в большинстве случаев появление мартенсита ускоряет начало превращения, но приводит к замедлению его окончания или ранней приостановке за счет стабилизации аустенит

Barcoding and Phylogenetic Inferences in Nine Mugilid Species (Pisces, Mugiliformes)

Accurate identification of fish and fish products, from eggs to adults, is important in many areas. Grey mullets of the family Mugilidae are distributed worldwide and inhabit marine, estuarine, and freshwater environments in all tropical and temperate regions. Various Mugilid species are commercially important species in fishery and aquaculture of many countries. For the present study we have chosen two Mugilid genes with different phylogenetic signals: relatively variable mitochondrial cytochrome oxidase subunit I (COI) and conservative nuclear rhodopsin (RHO). We examined their diversity within and among 9 Mugilid species belonging to 4 genera, many of which have been examined from multiple specimens, with the goal of determining whether DNA barcoding can achieve unambiguous species recognition of Mugilid species. The data obtained showed that information based on COI sequences was diagnostic not only for species-level identification but also for recognition of intraspecific units, e.g., allopatric populations of circumtropical Mugil cephalus, or even native and acclimatized specimens of Chelon haematocheila. All RHO sequences appeared strictly species specific. Based on the data obtained, we conclude that COI, as well as RHO sequencing can be used to unambiguously identify fish species. Topologies of phylogeny based on RHO and COI sequences coincided with each other, while together they had a good phylogenetic signal