Home – Home – Jornals – Advanced Search

A comprehensive study of water samples from the Medvezh’e, Yubileinoe, and Yamsoveiskoe oil-gas condensate fields was performed for the rapid identification of liquids from gas wells. The proportions of condensate, formation, and process waters in the produced mixture are assumed on the basis of their physicochemical parameters and chemical composition. Their dielectric parameters were studied at a frequency of 0.6 GHz. Dependences of the dielectric and radio emission parameters on the total salinity and concentrations of major cations have been established. Algorithms for identifying different types of well water based on their dielectric parameters are proposed.

A new method is suggested for calculation of transient electric-field response to conducting magnetically viscous earth excited by a grounded line source. Calculation algorithms are implemented in the computer program FwLL_MV. Using a conducting uniform, magnetically viscous half-space as an earth model, we have shown that magnetic relaxation affects the TEM response of equatorial and in-line arrays. As in the case of loop arrays, apparent resistivity steadily decreases with time. The higher the half-space resistivity and the shorter the offset, the earlier the voltage and the apparent resistivity begin to decrease as 1/ t . Magnetic relaxation and decay of eddy currents are independent processes within the range of resistivities typical of rocks.

The mechanochemical reduction of copper sulphide (Cu₂S) and lead sulphide (PbS) with elemental Fe as well as reduction of copper sulphide (Cu₂S) with silicon are studied. Metallic Cu and Pb are obtained due to the reducing power of iron and silicon, respectively. The obtained particles are characterized by XRD, VSM, SEM and TEM methods. While for Cu₂S and PbS the reduction by iron is rather straightforward leading to Cu and Pb metals in 10-23 nm dimensions, the process of Cu₂S reduction by silicon is more intricated. In this case the overall process proceeds via complicated mechanism with several overlapping steps. Phase transformations in copper sulphide phases, the formation of elemetal nanocopper with X-ray determined particle size of 23 nm and formation of ternary sulphide Cu₈SiS₆ with anomalous surface area values are the main products of the mechanochemical reaction.

A combination of First Principle Calculations (FPC) and statistical thermodynamics, i.e., the Cluster-Site Approximation (CSA), is applied to describe the bcc-based Fe-Al phase diagram. The formation energies of ordered compounds are calculated using Full-Potential Linearised Augmented Plane Wave (FP-LAPW) results, and the entropy term is evaluated using the so-called modified Cluster Variation Method (CVM). The CSA model has been used to model the bcc bases in the Fe-Al system. The results obtained from this combination are compared with those obtained from the irregular tetrahedron approximation of the CVM, with the same FP-LAPW total energies.

Mechanochemical (MC) treatment for degrading recalcitrant harmful PAH compounds (namely, anthracene and benzo[a]pyrene) adsorbed on marine sediments was investigated in laboratory. Optimal operating conditions (i.e., mill rotation speed, milling time, milling-to-milled mass ratio), together with explanation of their physical effects on sediment particle size and specific surface area were assessed, leading to fast (30-60 min) and very effective (>98 %) degradation of both contaminants under the experimental conditions investigated. Attempts carried out through HPLC analysis and DTA checks before and after MC treatment permitted to envisage likely pathways for chemical reactions occurring during the process, yielding amorphous carbon as final product. Further research is planned to exclude the formation of noxious gaseous by-products.

Results of a laboratory investigation aimed at determining technical efficiency as well as kinetics of chemical degradation of PCBs contaminating marine sediments by mechanochemical treatment with NaBH₄ are presented. Optimization of operating conditions allowed PCBs degradation to be achieved in very effective (>98 %) and fast (<30 min) manner. A kinetic approach to PCBs degradation accounting for variation of reaction rates for different PCB congeners was developed and a mathematical model useful for scaling-up MC treatment was convincingly achieved.

Amorphous solid electrolytes were synthesized in the systems Li₃N-P₂S₅ and Li₃N-P via mechanochemical route. Amorphous materials were obtained at the compositions with x = 50 and 60 in the system
xLi₃N×(100-x)P₂S₅ (mol. %), while crystalline Li₂S was obviously formed at the compositions with x = 70 and 80. The conductivity increased with increasing Li₃N content, and then decreased in the composition range x > 60. The highest conductivity of 2.2×10^-5 S/cm at room temperature was achieved at the composition with x=60. The formation of insulative Li₂S in the compositions with higher Li₃N content is responsible for the decrease of conductivity. Li₃N was reacted with P instead of P₂S₅ by milling in order to prevent the formation of Li₂S. The obtained materials were basically amorphous, but partially included crystalline materials such as Li₃P and Li₇PN₄. The 80Li₃N×20P (mol. %) material exhibited the highest conductivity of 1.0×10^-5 S/cm at room temperature in the system Li₃N-P.

The contribution describes chemical, physical and mineralogical properties of so-called Albanian (ore origin) leaching residuum from dumping ground of former Sered' Nickel Works (West Slovakia). The main mineral component of this residuum represents synthetic magnetite, which is known by its ability to sorb some substances. The changes in grain size and specific surface were studied as a function of grinding time and mill. The activation in ball mill during 25 min resulted in a two-fold increase in specific surface. Contrary to this fact, grinding in attritor led to a three-fold increase in specific surface already after 15min, i.e. from 1.31 to 3.86 m²/cm³.
For adsorption tests and following magnetic filtration the leaching residuum ground in the solution of K₄Fe(CN)₆ was applied. Obtained results point to the fact, that magnetic sorbent prepared in such a way and magnetic filtration enable substantial reduction of ion concentration of heavy metals such as copper, manganese and zinc.

High-energy ball-milling in hexane medium was employed to prepare amorphous Al-La-Fe-Ni alloys of three different nominal compositions (Al₈₂La₁₀Ni₄Fe₄, Al₈₅La₉Ni₃Fe₃ and Al₈₈La₆Ni₃Fe₃). Using a planetary ball mill (AGO-2) at a rotational speed of 300 rpm, nearly complete amorphization could be achieved for the Al₈₂La₁₀Ni₄Fe₄ alloy after milling for 350 h. In contrast, the Al₈₅La₉Ni₃Fe₃ and Al₈₈La₆Ni₃Fe₃ samples remained crystalline to a certain extent even after prolonged milling and contained fcc Al crystallites. The glass forming ability was found to increase with decreasing Al and increasing La content, which can be ascribed to the enhanced atomic size mismatch of the constituents on La addition. Amorphous Al₈₂La₁₀Ni₄Fe₄ powder undergoes two-stage crystallization with onset temperatures at 640 and 700 K and glass transition at 566 K. Differences to DSC traces of previously studied melt-spun samples are believed to be mainly due to carbon impurity incorporation and compositional changes during milling. Taking into account the DSC data, consolidation of amorphous Al₈₂La₁₀Ni₄Fe₄ powder was attempted by means of spark-plasma sintering at a temperature of 613 K and applied pressures of 400 and 600 MPa. Compacts produced under these conditions were found to have relative densities of 80 and 96 %, respectively.

Mechanochemistry-assisted treatment (MT) was applied for the first time to extract isofraxidin from Acanthopanax senticosus using water as solvent. Six extraction variables, i.e. solvent, Na₂CO₃ content, sample granularity, extraction time, liquid/solid ratio (ml/g), extraction temperature were investigated with respect to the yield of isofraxidin. The most favourable conditions were obtained by using superfine powered plant material (D₉₅ of 47 mm) with Na₂CO₃ content of 0.5 mass %, extracted with water (liquid/solid ratio of 20:1, ml/g) for 3 min at 25 ^oC. The results obtained using the optimized conditions were compared to those with heat reflux extraction. MT extraction was found to increase the yield of isofraxidin considerably while excluding organic solvents and reducing both extraction time and temperature.