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Košice, Slovakia

Vinas P.,University of Murcia | Campillo N.,University of Murcia | Andruch V.,Pavol Jozef Safarik University
TrAC - Trends in Analytical Chemistry

We give an overview of achievements in solidified floating organic drop microextraction (SFODME). We focus on the types of analyte investigated, the types of sample analyzed, the sample-pre-treatment procedures used, including derivatization and complexation, and we cover the articles available on-line up to 30 November 2014. SFODME has been applied to the determination of organic compounds and inorganic analytes. Although most extraction methods based on SFODME have been applied to water samples, the technique has also been used for analysis of other types of samples. We also briefly discuss the effects of different variables. We discuss the various modalities of SFDOME. Tables summarize the applications, selected experimental conditions and the most important parameters of SFODME. © 2015 Elsevier B.V. Source

SEM, EDS, TEM, FTIR and UV-vis analysis were used to investigate the biosorption, bioaccumulation and bioreduction of silver by the freshwater green alga Parachlorella kessleri. The dead algal biomass showed high potential for silver removal; 75% of silver was removed within 2 min. Surface sorption was the main mechanism; bioreduction contributed to the biosorption only to a small extent. In the presence of living P. kessleri cells a 68% decrease of silver concentration was observed within 24 h, but subsequently the majority of silver was released back into the solution within the next 14 days. According to UV-vis spectrometry, silver nanoparticles were formed in that time. The nanoparticles produced by the alga exhibited a lower toxicity against algal cells than silver ions at the same silver concentrations. The study demonstrated that living algal cells used a combination of two main mechanisms (sorption and reduction) for silver detoxification in their environment. © 2016 Elsevier Ltd. Source

Hofierka J.,Pavol Jozef Safarik University | Zlocha M.,State Geological Survey of Dionyz Stur
Transactions in GIS

Estimates of solar radiation distribution in urban areas are often limited by the complexity of urban environments. These limitations arise from spatial structures such as buildings and trees that affect spatial and temporal distributions of solar fluxes over urban surfaces. The traditional solar radiation models implemented in GIS can address this problem only partially. They can be adequately used only for 2-D surfaces such as terrain and rooftops. However, vertical surfaces, such as facades, require a 3-D approach. This study presents a new 3-D solar radiation model for urban areas represented by 3-D city models. The v.sun module implemented in GRASS GIS is based on the existing solar radiation methodology used in the topographic r.sun model with a new capability to process 3-D vector data representing complex urban environments. The calculation procedure is based on the combined vector-voxel approach segmenting the 3-D vector objects to smaller polygon elements according to a voxel data structure of the volume region. The shadowing effects of surrounding objects are considered using a unique shadowing algorithm. The proposed model has been applied to the sample urban area with results showing strong spatial and temporal variations of solar radiation flows over complex urban surfaces. © 2012 Blackwell Publishing Ltd. Source

Lukacova-Medvid'ova M.,Johannes Gutenberg University Mainz | Rusnakova G.,Johannes Gutenberg University Mainz | Rusnakova G.,Pavol Jozef Safarik University | Hundertmark-Zauskova A.,Johannes Gutenberg University Mainz
Computer Methods in Applied Mechanics and Engineering

In this paper we study a kinematic splitting algorithm for fluid-structure interaction problems. This algorithm belongs to the class of loosely-coupled fluid-structure interaction schemes. We will present stability analysis for a coupled problem of non-Newtonian shear-dependent fluids in moving domains with viscoelastic boundaries. Fluid flow is described by the conservation laws with nonlinearities in convective and diffusive terms. For simplicity of presentation the structure is modelled by the generalized string equation, but the results presented in the paper may be generalized to more complex structure models. The arbitrary Lagrangian-Eulerian approach is used in order to take into account moving computational domain. Numerical experiments including numerical error analysis and comparison of hemodynamic parameters for Newtonian and non-Newtonian fluids demonstrate reliability of the proposed scheme. © 2013 Elsevier B.V. Source

Novotny M.,Pavol Jozef Safarik University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

The Canvas protocol was developed by Harald Vogt [10] and should provide data integrity in Wireless Sensor Networks. However, Dieter Gollmann published [5] an attack on the protocol. This example supports a widespread belief that design of security protocols is notoriously error-prone. Therefore, it is required to use formal methods to analyze their security properties. In the paper we present design and analysis of a generalized Canvas protocol. We consider the fallacy of the Canvas scheme in different models of the attacker and present a solution for correcting the scheme. We discuss a motivation for generalization of the Canvas protocol and introduce a k-generalized version of the scheme for some parameter k ≥ 2. We build a formal model of the k-generalized Canvas protocol in the applied pi-calculus. This model includes a model of the network topology, communication channels, captured nodes, and capabilities of the attacker. In the semantic model of the applied picalculus we specify the data integrity property of the scheme. We prove that the proposed k-generalized Canvas scheme, in the presence of an active adversary, provides data integrity of messages assuming that at least one honest node exists on each path of the length k-1 in the communication graph of a sensor network. Finally, we discuss the usability of the proposed formal model for other WSN security protocols. © IFIP International Federation for Information Processing 2010. Source

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