A comparative analysis of gaseous phase hydration properties of two lichenized fungi: Niebla tigrina (Follman) Rundel & Bowler from Atacama Desert and Umbilicaria antarctica Frey & I. M. Lamb from Robert Island, Southern Shetlands Archipelago, maritime Antarctica

Gaseous phase hydration properties for thalli of Niebla tigrina from Atacama Desert, and for Umbilicaria antarctica from Isla Robert, maritime Antarctica, were analyzed using 1H-NMR relaxometry, spectroscopy, and sorption isotherm analysis. The molecular dynamics of residual water was monitored to distinguish the sequential binding very tightly, tightly, and loosely bound water fractions. These two species differ in hydration kinetics faster for Desert N. tigrina [A1 = 0.51(4); t1 = 0.51(5) h, t2 = 15.0(1.9) h; total 0.7 for p/p0 = 100%], compared to Antarctic U. antarctica [A1 = 0.082(6), t1 = 2.4(2) h, t2 = [26.9(2.7)] h, total 0.6 for p/p0 = 100%] from humid polar area. The 1H-NMR measurements distinguish signal from tightly bound water, and two signals from loosely bound water, with different chemical shifts higher for U. antarctica than for N. tigrina. Both lichen species contain different amounts of water-soluble solid fraction. For U. antarctica, the saturation concentration of water soluble solid fraction, cs = 0.55(9), and the dissolution effect is detected at least up to Δm/m0 = 0.7, whereas for N. tigrina with the similar saturation concentration, cs = 053(4), this fraction is detected up to the threshold hydration level equal to ΔM/m0 = 0.3 only.

The results of studies on the extension of methodological capabilities of determining physico-chemical conditions of lead-based liquid-metal coolants

The authors consider examples of using the thermal cycling method for heavy lead- and lead-bismuth-based coolants with simultaneous measurement of the thermodynamic activity (TDA) parameter of oxygen impurities. In these experiments, structural EI852 and EP823 ferritic-martensitic steels as well as EP302 austenitic steel were used as sources of iron impurities. As a result of the experiments, it was found that iron oxides previously formed in the coolant, as such or in the form of an oxide film on the structural steels, are not inert phases in heavy coolants, but can exchange iron and oxygen with the melt. The nature of this exchange depends both on the actual coolant impurity state and on external conditions, including, first of all, temperature. The experimental data obtained by thermal cycling of lead- and lead-bismuth coolants were analyzed both in the region of relatively high oxygen TDA values close to the oxygen saturation concentration and in the region of sufficiently low values of this parameter close to the saturation concentration of iron impurities. It is concluded that the proposed coolant thermal cycling method is informationally significant and can be recommended for further use, for example, to obtain quantitative data on the content of iron impurities in the coolant.

Reducing the Hygroscopic Swelling in MEMS Sensor using Different Mold Materials

Today, Hygroscopic swelling is one of the biggest challenging problem of Epoxy mold compound (EMC) in packaging with Microelectromechanical system (MEMS) devices. To overcome this hygroscopic swelling problem of EMC and guard the devices, MEMS devices are molded in this paper with different Mold Compound (MC) i.e. titanium and ceramic etc. during their interconnection with the board. Also, a comparatively performance analysis of this various mold compound with MEMS pressure sensor has been studied in this paper at 60% humidity, 140 mol/m³ saturation concentration and 25 ^oC. It was observed that hygroscopic swelling does not take place in the titanium mold compound. But, titanium is very costly so we have to consider something cheaper material i.e. ceramic in this paper. The Hygroscopic swelling in Ceramic Mold Compound after 1 year is nearly 0.05mm which is very less than epoxy.

Elaboration and mastering of technology of semiproduct smelting in EAF under magnesia slags

Technology of magnesia slags forming provides increase of electric energy utilization efficiency and furnace lining resistance due to early formation of stable slag foam and decrease of aggressive slag impact on the lining. At the same time the practice of operation with magnesia slags shows, that excessive over-saturation them by magnesium oxide results in heterogenization, decrease of refining properties and deterioration of some technological, technical and economic process indices. Therefore, study and elaboration technology of rational composition magnesia slags forming by periods of a heating in EAF is an actual task. Results of numerical simulation of slag temperature and chemical composition effect on MgO saturation concentration during different melting periods in EAF presented. Besides, results of analysis of refining abilities of magnesia slags depending on MgO saturation degree also presented study of magnesia slags viscosity effect depending on MgO basicity and saturation concentration, as well as magnesia slag chemical and phase composition effect on foaming efficiency. Results of theoretical and experimental study were used as a base of elaboration rational slag composition by periods of melting in the EAF and technological techniques of their formation. A technology elaborated and implemented at PAO “Seversky pipe plant” EAF shop by leaving some amount of high-magnesia slags of the previous heat and addition in two stages high-magnesia flux of “Magma” grade during the oxidizing period. This resulted in a record resistance of the refractory EAF lining, exceeding 1900 heats within a campaign and a high level of technological, technical and economic process indices.

INFLUENCE OF B2O3 AND CaO–SiO2 –B2O3 –Al2O3 SLAG SYSTEM BASICITY ON CONCENTRATION OF MAGNESIUM OXIDE SATURATION

Study of the effect of boron oxide and basicity of CaO – SiO2–B2O3 – Al2O3slag system on MgO saturation concentration was carried out using the simplex lattice method of experimental design, which allows one to construct mathematical models describing dependence of studied property on composition as a continuous function. Synthetic slags, corresponding in composition to vertices of studied simplex, were smelted in graphite crucibles from previously calcined oxides of analytical grade. Slag compositions corresponding to the remaining points of local simplex plan were obtained by counterblending slags of simplex tops. Using experimental data, mathematical models adequately describing effect of slag composition on saturation concentration of MgO were constructed. Graphic image of mathematical modeling results is represented by the composition diagram – saturation concentration of MgO. Analysis of experimental data presented in diagram made it possible to obtain new information on the effect of boron oxide and basicity of CaO – SiO2 – B2O3slags system containing Al2O3on MgO saturation concentration. It was established that in slags formed in basicity range of 2 – 3 and B2O3content of 1 – 3 %, saturation concentration of MgO varies from 3 to 9 %. Increase in B2O3content in slag to 4 % leads to an increase in MgO saturation concentration in slag of 11 – 13 %. Displacement of slags to area of increased basicity up to 3 – 4 is characterized by a decrease in MgO saturation concentration to 2 – 5 %, with 1 – 3 % of В2О3content and an increase to 7 – 9 % at 3 – 4 % В2О3in slag. Formation of slags in basicity range of 4 – 5 and B2O3content of 1 – 3 % does not lead to a significant decrease in concentration of slag saturation with magnesium oxide. Saturation concentration of MgO in slag in this area of basicity varies from 2 to 4 % and practically does not reach 7 % with an increase in В2О3content to 4 %. At the same time, there is an increase in cost of steel due to an increase in consumption of lime and material containing boron oxide.

The lifetimes of evaporating sessile droplets are significantly extended by strong thermal effects

The evaporation of sessile droplets is analysed when the influence of the thermal properties of the system is strong. We obtain asymptotic solutions for the evolution, and hence explicit expressions for the lifetimes, of droplets when the substrate has a high thermal resistance relative to the droplet and when the saturation concentration of the vapour depends strongly on temperature. In both situations we find that the lifetimes of the droplets are significantly extended relative to those when thermal effects are weak.