CSA Technology Research Database

Graphene oxide (GO) are novel nanomaterials with a wide range of applications due to their high absorption capacity. This study was undertaken with a view to assess the bioaccumulation and acute toxicity of GO used in combination with the heavy metal mixture (Cr, Cu, Ni and Zn) to fish embryos and larvae. For this purpose, Salmo trutta embryos and larvae were subjected to the 4-day long treatment with three different concentrations of GO, the metal mixture, which was prepared of four metals at the concentrations corresponding to the maximum-permissible-concentrations for EU inland waters (Cr-0.01, Cu-0.01, Ni-0.034, and Zn-0.1 mg/L), and with GO in combination with MIX (GO+MIX). When used in combination with the metal mixture, GO exhibited a high metal sorption capacity. The obtained confocal fluorescence microscopy results showed that GO located in the embryo chorion causing its damage; in larvae, however, GO were found only in the gill region. Results of these experiments confirmed the hypothesis that GO affects the accumulation of metals and mitigates their toxic effects on organism. In embryos, the acute toxicity of exposure to GO and co-exposure to MIX+GO was found to manifest itself through the decreased heart rate (HR) and malondialdehyde (MDA) level and through the increased metallothionein (MT) concentration. Meanwhile, in larvae, GO and MIX+GO were found to induce genotoxicity effects. However, changes in HR, MDA, MT, gill ventilation frequency, yolk sack absorption and cytotoxicity compared with those of the control group were not recorded in larvae. The obtained results confirmed our hypothesis: the combined effect of MIX and GO was less toxic to larvae (especially survival) than individual effects of MIX components. However, our results emphasize that fish exposure to GO alone and in combination with heavy metal contaminants (MIX+GO) even at environmentally relevant concentrations causes health risks that cannot be ignored.

Quantum dots (QDs) are extensively explored in biomedicine but the understanding of the mechanism underlying the uptake of colloidal QDs by biological systems is still poor. The knowledge of their distribution in tissues and their possibilities to cross biological barriers, especially at early stages of organism development, is also still limited. The potential risk of nanoparticle exposure to aquatic organisms is continuously questioned in ecotoxicology. To answer this question, we investigated the interaction (penetration and distribution) of CdSe/ZnS-COOH QDs with the chorion as well as their toxicity, cytotoxicity and genotoxicity in “eye-egg” stage embryos of rainbow trout Oncorhynchus mykiss. Results of the confocal fluorescence microscopy, fluorescence spectroscopy and 3D image analysis of O. mykiss chorion showed that it consists of three different layers and has a hexagonal pattern of pores distribution. The present study has revealed that both the accumulation and the distribution of QDs within the chorion are related to its structure. QDs are accumulated in pore canals of the external membrane of a fertilized O. mykiss egg. Our study has shown that QDs exposure induces bradycardia in O. mykiss and, as a result, cardiac toxicity in embryos. However, embryo survival rates as well as cytotoxicity and genotoxicity effects in the fish exposed to QDs for 1 day were not found to differ significantly from those in 4-day exposed fish. Results of the mathematical modelling showed the adsorption of QDs aggregates on the outer surface of the chorion leading to the oxygen-deficient microenvironment in embryos. These results represent an important step forward towards a better understanding of the mechanisms underlying QDs impacts on living organisms, which is essential for clarifying the protective properties of biological structures, and is valuable for the evaluation of nanotoxicity to fish at early development stages.

In the paper, the variation of the intensity of the geomagnetic field force is analysed in time and space. For the research, the data from measurements of the intensity of the geomagnetic field force at four airports (Kaunas, Klaipėda, Palanga and Vilnius) and 6 geomagnetic field repeat stations aswell as the data from Belsk Magnetometric Observatory (Poland) were used. For the data analysis, the theory of covariance functions was applied. The estimates of the cross-covariance functions of the measured intensity of the geomagnetic field force or the estimates of auto-covariance functions of single data were calculated according to the random functions created from the force intensity measurement data arrays. The estimates of covariance functions were calculated upon varying the quantization interval on the time scale and applying the software created using Matlab package of procedures. The impact of radars of airports on the intensity of geomagnetic field variation and on changes of their covariance functions was established.

The accuracy of vehicle speed measured by a speedometer is analysed. The stress on the application of skew normal distribution is laid. The accuracy of measured vehicle speed depends on many error sources: construction of speedometer, measurement method, model inadequacy to real physical process, transferring information signal, external conditions, production process technology etc. The errors of speedometer are analysed in a complex relation to errors of the speed control gauges, whose functionality is based on the Doppler effect. Parameters of the normal distribution and skew normal distribution were applied in the errors analysis. It is shown that the application of maximum permissible errors to control the measuring results of vehicle speed gives paradoxical results when, in the case of skew normal distribution, the standard deviations of higher vehicle speeds are smaller than the standard deviations of lower speeds. In the case of normal distribution a higher speed has a greater standard deviation. For the speed measurements by Doppler speed gauges it is suggested to calculate the vehicle weighted average speed instead of the arithmetic average speed, what will correspond to most real dynamic changes of the vehicle speed parameters.

Terrestrial laser scanning (TLS) is one of the instruments for remote detection of damage of structures (cavities, cracks) which is successfully used to assess technical conditions of building objects. Most of the point clouds analysis from TLS relies only on spatial information (3D–XYZ). This study presents an approach based on using the intensity value as an additional element of information in diagnosing technical conditions of architectural structures. The research has been carried out in laboratory and field conditions. Its results show that the coefficient of laser beam reflectance in TLS can be used as a supplementary source of information to improve detection of defects in constructional objects.

In Lithuania, the old archival topographic maps of locations of small and medium scale and 1 : 10,000 scale contour photo plans were created on the basis of aerial images. The material of these scales provides documented records on the condition of the objects in the location and the landscape at the moment of aerial photography. Those maps can be used to restore the accurate topographic image of the terrain and buildings in 1945–1951 and in later years and perform the necessary topographic, photogrammetric, and geodetic measurements of the parameters of objects, to identify the location of objects and changes. This information is necessary for a variety of disputed property issues and for building farmhouses in reserves, in areas of forestry land parcels, and for assessment of changes in the landscape. Studies of landscape changes are needed for the assessment of renaturalization processes. This paper presents the geodetic method used for geomorphological changes at the channel of River Žalesa during the period 1942–2017, based on the collected archival cartographic materials: historical topographic maps from archive of the Lithuanian State Company Land Fund, Land Information System, and land management projects and orthophoto maps from Lithuanian spatial information portal and free open-access Sentinel-1 satellite data from the Copernicus Open Access Hub.

Since the beginning of the IEEE 802.11 technology its channel access in ISM bands was governed by simple rules to ensure fairness and co-existence: such as upper ceiling on maximum transmitted power, moderate out-of-band emission masks and requirement for tolerance to interference. However, over time these rules became outdated and no longer well suited for current capabilities of devices operating in ISM bands. In this paper we propose a new channel access model for IEEE 802.11 and other devices using unlicensed ISM bands at 2.4 GHz and 5 GHz based on Game Theoretic principles and Cognitive Radio features. It is shown that the proposed channel access method can significantly improve the efficiency of spectrum usage, as well as the quality of service that is experienced by users of ISM bands. Moreover, it would allow abolishing constraint on maximum transmission power and making unnecessary the use of CSMA/CA protocol by replacing it by more advanced Multi-Polling with Game Theory (GT) based protocol.

The purpose of this work was to develop a novel morphology of gas sensing layer based on porphyrin sheets and nanotubes and to investigate the physical-chemistry and sensing properties of the porphyrin layer. In the present work the porphyrins nanoparticles were synthesized by ionic selfassembly in aqueous solutions of two oppositely charged non-metal porphyrins, namely, the anionic Meso-tetra (4-sulfonatophenyl) porphine dihydrochloride (TPPS4) and cationic Meso-tetra (4-pyridyl) porphine (T4MPyP) and an ethanol was not added to the solution. We investigated in details the nanosheets and nanotubes formation and behaviors of aggregation induced by mixing an anionic TPPS4 and cationic T4MPyP acidic solutions by means of the UV-vis spectroscopy and aggregates structure and morphology by transmission electron microscopy (TEM), scanning electron microscopy (SEM). The sensing capabilities of the samples have been finally evaluated by exposing the films to the different concentration of ethanol atmospheres.

Currently, the construction of low energy buildings in Europe is promoted. Existing and newly developed design and construction concepts for such buildings are adapted to their national or regional climatic conditions. The European Parliament has assigned the member countries to get ready for the reduction of the energy consumption in buildings. Therefore, Lithuania, like other EU countries, must be examined for the use of the low energy building design and construction experience, the existing concepts of low energy buildings should be adapted or new concepts of low energy building responding to the region's climate should be created. In this article, the most popular European mid-region passive house concept and the energetic performance of the house, designed and built according to its requirements is analyzed, the main differences of this concept to the normative requirements of Lithuanian building regulations and proposals to improve provisions for the construction of low energy buildings in Lithuania is provided.

The paper addresses one engineering design problem, the optimization of pile placement schemes under grillage-type foundations. Aim of the optimization is to find pile placement scheme where the number of piles is minimal and reactive forces at all piles do not exceed the given allowable reaction. This global optimization problem is solved here using the simulated annealing algorithm which proved to be one of the most promising algorithms for grillage optimization. Optimization of real-life grillages using PC requires usually unacceptably long for engineering practice computation time, therefore present paper investigates the possibilities of employing grid computing for that. Numerical examples presented clearly show potential of grid computing in engineering design problems.