Permeable membranes PUR/TETA and PUR/TEPA for CO2 capture prepared with one-step electrospinning technology

A simple one-step technology of wire electrospinning is presented for the manufacturing of air-permeable CO2-capturing membranes, easily transferable to industrial production lines. The design of the chemically-modified polyurethane nanofiber membranes for CO2 capture was based on a combination of molecular modeling and technological experiments using one-step electrospinning (i.e., a modifying agent dissolved directly in a spinning solution). Polyurethane (PUR Larithane), chemically modified by TETA/TEPA amines, was used in the present study for the membrane design. Special attention was paid to two key parameters significant for the design of the functional unit, i.e., the CO2 sorption capacity and air permeability which depended on the amine concentration. The optimal combination of these parameters was found for the PUR/TEPA membrane (5 wt.% of TEPA in spinning solution): the sorption capacity was 13.97 cm(3)/g with an air permeability of 0.020 m/s. Molecular modeling proved to be a valuable tool that helped to clarify, at the molecular level, the structure of chemically-modified nanofibrous membranes.Web of Science1011art. no. 10

Impacts of EU visa policy on incoming of Czech republic

The main purpose of the thesis is to evaluate the impacts of EU visa policy on incoming of Czech republic. For achieving this main purpose there were also defined sub-goals, which include comparison of the indicators of inbound tourism in Czech republic before and after joining Schengen Area and assessment of economic impact of applied EU visa policy on Czech republic. The diploma thesis is divided into seven chapters. The first three chapters introduce the theoretical overview of basic terms in the international tourism, statistical monitoring of tourism and visa policy. The next part of the thesis is devoted to analyzing the influence of EU visa policy on selected countries whose nationals require visas to EU. The final chapter appraises the results and brings the forecast of the situation without existence of common visa policy.Hlavním cílem diplomové práce je zhodnotit dopady vízové politiky Evropské unie na příjezdový cestovní ruch České republiky. Pro dosáhnutí prvotního cíle byly vymezeny dílčí cíle, ke kterým patří porovnání ukazatelů příjezdového cestovního ruchu České republiky před a po vstupu do Schengenského prostoru a vyčíslení ekonomického dopadu uplatňované vízové politiky Evropské unie pro Českou republiku. Diplomová práce je členěna do sedmi kapitol. První tři kapitoly představují teoretickou část, tedy přehled základních pojmů z mezinárodního cestovního ruchu, statistického sledování cestovního ruchu a vízové politiky. Další kapitoly jsou věnovány analýze vlivu vízové politiky EU na vybrané země, jejichž občané mají vízovou povinnost vůči EU. V poslední kapitole jsou vyhodnoceny dosažené výsledky a provedena prognóza situace bez existence společné vízové politiky

Impacts of EU visa policy on incoming of Czech republic

The main purpose of the thesis is to evaluate the impacts of EU visa policy on incoming of Czech republic. For achieving this main purpose there were also defined sub-goals, which include comparison of the indicators of inbound tourism in Czech republic before and after joining Schengen Area and assessment of economic impact of applied EU visa policy on Czech republic. The diploma thesis is divided into seven chapters. The first three chapters introduce the theoretical overview of basic terms in the international tourism, statistical monitoring of tourism and visa policy. The next part of the thesis is devoted to analyzing the influence of EU visa policy on selected countries whose nationals require visas to EU. The final chapter appraises the results and brings the forecast of the situation without existence of common visa policy

Polarographic and voltammetric determination of 2,2'-dinitrobiphenyl

Katedra analytické chemieDepartment of Analytical ChemistryPřírodovědecká fakultaFaculty of Scienc

Polarographic and voltammetric determination of 2,2'-dinitrobiphenyl

Katedra analytické chemieDepartment of Analytical ChemistryPřírodovědecká fakultaFaculty of Scienc

Characterization of special oxidic anticorrosive pigments by XRD and XFR analysis

Spinel type pigments were analyzed by X-ray fluorescence spectrometry and X-ray powder diffraction. X-ray fluorescence spectrometry determined the contents of specific elements and X-ray diffraction determined the crystalline structure of the samples. Three samples of spinel pigments were analyzed as such and after their application to aluminum and carbon core. The results of XRD showed the presence of crystalline phase of the pigment and also small amount of Fe2O3 and also the diffraction lines of the cores. The XRF analysis showed the presence of the elements from which were the pigments prepared and also trace amounts of impurities (P2O5, SO3)

Specific structure, morphology, and properties of polyacrylonitrile (PAN) membranes prepared by needleless electrospinning; Forming hollow fibers

Polyacrylonitrile (PAN) membranes have been prepared using needleless electrospinning with wire electrode and characterized by a series of methods HRSEM, XRD, air permeability and area weight measurements in dependence of high voltage and electrode distance. HRSEM analysis revealed the tendency to longitudinal rolling of strip-shaped PAN fibers forming hollow fibers. Combination of XRD analysis and molecular modeling explains this phenomenon as the consequence of the specific crystal structure of PAN fibers, where the isotactic PAN chains are arranged in layers forming belt shaped nanofibers with the strong tendency to roll up longitudinally forming hollow fibers. This effect offers the possibility to create hollow nanofibers by electrospinning with the appropriate choice of structure of polymer chains.Web of Science105art. no. 11015

Study of Surface Morphology, Structure, Mechanical And Tribological Properties of an Alsin Coating Obtained by the Cathodic Arc Deposition Method

AlSiN coatings were prepared by the cathodic arc deposition method at a temperature of 400 °C and pressure of 2.6 Pa. The chemical composition, determined by SEM/EDS analysis, shows that the AlSiN coating presented here has a stoichiometry structure (Al40Si9N51). XPS and XRD analyses indicated AlN in both cubic and hexagonal modifications in the coating, and that the coating has a not fully completed nanocomposite structure. Nanoindentation measurements indicate nanohardness and elastic modulus of 39 GPa and 389 GPa, respectively. The coating has a very good adhesion strength with an average critical load of 28.3N (first cohesive failure) and 62.3N (first adhesion failure). The estimated wear rate and coefficient of friction of the coating are 27.2 × 10−6 mm3 N−1 m−1 and 0.7, respectively (using the friction pair AlSiN/Al2O3)