ISI Web of Science

Here, we present for the first time the rigorous boundary problem solution of the Maxwell’s equations for the determination of scattering characteristics of a structure. The structure consists of a finite set of infinite parallel circular cylinders that can be made of different lossy isotropic materials. We numerically analyzed two structures that differ only in the symmetrical arrangement of semiconductor cylinders in relation to a central metamaterial cylinder. The electrical radii of cylinders can be arbitrary. Both polarizations of the incident microwave are considered in this work. The Poynting vector of the plane microwave that reflected from and transmitted through the structures analyzed here. We investigated dependency on the radius of an arc where are placed the semiconductor cylinders, the semiconductor-specific resistivity, the operating frequency at two radii of the metamaterial cylinder. We discovered that the structure can have features of a band gap photonic crystal dependent on the topology and the polarization of the incident microwave. We have found that the structure can operate as a microwave reflector at the certain radius of the arc on which are located thirteen n-Si cylinders. The Poynting vector is very sensitive to the change of semiconductor-specific resistivity when the incident microwave has the parallel polarization.

Thallium sulfide layers of varying composition form on the surface of low-density polyethylene (PE) when the PE films have been sulfurized in a solution of higher polythionic acid H2S33O6, and then immersed in the alkaline solution of thallium (I) sulfate. The concentration of sulfur sorbed-diffused into PE surface increases with the increase of the sulfurization time and concentration of higher polythionic acid solution. The concentration of thallium in the Tl (x) S (y) layers depends on the sulfur concentration sorbed-diffused into PE, the concentration, and temperature of thallium (I) sulfate solutions. By chemical analysis of the obtained sulfide layers it was determined that the values of x and y in the TlxSy layers varies in the intervals: 1 < x < 3, 1 < y < 6. Two phases TlS, Tl2S2 were identified by X-ray diffraction analysis in thallium sulfide layers. Scanning Electron (SEM) and Atomic Force (AFM) microscopies were used to characterize surface morphology of thallium sulfide layers. The films deposited on the PE surface have a non-homogeneous structure, and consist of separated islands.

An investigation of the spatial variability of topsoil contamination level was performed in 49 preschool playgrounds located in Vilnius city and correlated with urban (height and age of the preschools and height of surrounding buildings) and natural (altitude) factors. Composite samples, consisting of 20-30 sub-samples, were collected from 10 cm topsoil layer with a 3-5 m distance from each other. Sieved fraction (b0.63 mm) was ashed at 400 °C, ground to b1.0 μm and analysed for the real total concentrations of 22 trace elements (Ag, B, Ba, Co, Cr, Cu, Ga, Li, Mn, Mo, Nb, Ni, Pb, Sc, Sn, Sr, Ti, V, Y, Yb, Zn and Zr) using optical atomic emission spectrophotometry. Information on construction year and height (number of building stories) of preschool and surrounding buildings was acquired from the Centre of Registers of Lithuania. Out of 22 analysed elements, 13 to a greater extent exceeded the background values in several areas and were used to calculate the total contamination index (Zs13). Out of 49 analysed areas, 21 had moderately hazardous to hazardous levels of contamination as indicated by Zs13. The main contaminating elements, exceeding the permissible concentrations were Ag, Cu, Mo, Pb, Sn and Zn, the origins of which coincide with city industry and traffic. Topsoil around the newer preschool buildings, despite their location, contained lower concentrations of contaminants, while areas at higher altitudes were more contaminated than those located at lower altitudes. The latter causality is biased, as the city industry, and hence the highest contamination, is in districts located higher above sea level than the remaining studied sites.

Investigation on 137Cs and 239,240Pu activity concentration was undertaken in a coastal zone of the Baltic Sea on the Lithuanian territory to study the vertical distribution of radionuclides (down to 30 cm). The Baltic seaside is one of the regions where the highest radionuclide concentrations after the Chernobyl NPP accident were detected. Moreover, this area is a significant recreational zone, therefore, peculiarities of radionuclide spreading in the environmental ecosystem are important from the radioecological point of view. The obtained results of vertical distribution of 137Cs and 239,240Pu in sand and forest soil suggest that the radionuclide downward migration depends on the structure of matrix and its chemical composition. Besides, the results of radionuclide distribution on the stripe between the Baltic Sea and the Curronian Lagoon indicate that the sea is a possible source of radioactive contaminants.

The biological effects of low-dose radiation have attracted attention, but data are currently insufficient to fully understand the beneficial role of the phenomenon. In the present study, we have investigated the effects of low doses of gamma-irradiation alone and in combination with all-trans-retinoic acid (RA) on proliferation, apoptosis and differentiation of the human promyelocytic leukemia HL-60 cells. Changes in cell behavior and protein expression were determined with the use of light and fluorescent microscopy, immunocytochemical and Western blot analysis. Low-dose irradiation with 1–100 cGy caused a dose-dependent inhibition of HL-60 cell proliferation, and induced apoptosis and differentiation to granulocytes with an increase in the number of CD15-positive cells. Pre-irradiation with 1–100 cGy for 24 h before treatment with RA promoted apoptosis but did not impair RA-induced differentiation. Both processes were associated with a decrease in the expression of the proliferating cell nuclear antigen (PCNA), BCL-2, c-MYC, and changes in both cytosolic and nuclear levels of protein tyrosine-phosphorylation as well as protein kinase C alpha or beta isoforms. These results demonstrate the beneficial role of low-dose irradiation in modulating leukemia cell proliferation, differentiation and apoptosis.

Carbon nanotube layers prepared as coatings on silica fibers are found to be suitable for terahertz detection in 0.5–7.3 THz range within temperatures of 4.2–70 K. In time-domain of terahertz excitation, two following constituents in the photoresponse are discriminated: the first one is attributed to the bolometric effect while the other one is related to the photoconductivity caused by the terahertz-induced hopping effect. In frequency domain, nonmonotonic behavior of the photoconductivity is associated with prevailing carbon nanotube-induced antenna effects in the electronic transport. The experimental observations are supported by theoretical estimates.

This paper presents a set of data obtained in experimental and theoretical studies of the indoor ozone concentration with displacement of the ozone source. The measurements were conducted for three typical room configurations. The simulation takes into account actual room sizes and deposition rates on the surface material to predict the indoor ozone concentration. Both experimental and simulated results suggest that the air exchange rate and the material surface in the room play a significant role in determining ozone levels in indoor environments. The simulated indoor ozone concentration was compared with experimental results (correlation r = 0.8), and the accuracy of the model was tested.

The magnetoresistance of thin polycrystalline La1-xSrxMnO3 films deposited on lucalox substrate using metal organic chemical vapor deposition technique was investigated in pulsed magnetic fields up to 18 T in the temperature range 100-320 K. The influence of film preparation conditions, ambient temperature variation and Sr content is analyzed in order to determine the optimal conditions for the design of CMR-B-scalar magnetic field sensor based on thin manganite film, operating at room temperature.

Colossal magnetoresistance effect B-scalar magnetic field sensors with effective areas of 0.05 mm2 were used very close to the rails for magnetic field measurements. These measurements were performed during static and dynamic railgun experiments. In static experiments three different rail materials were used and the results are compared to a finite element simulation.

The destructive laboratory device, generating half-period sinus-shaped magnetic field pulses of 0.15-2 ms duration is investigated numerically. The coil was placed into a steel reinforcement cylinder to resist magnetic forces, while in°uence of thickness of the reinforcement cylinder is considered in detail. The time-dependent non-linear magneto-mechanical model and the finite element software ANSYS are employed. On the basis of the mechanical analysis, reasonable explanation of the destruction nature is provid.