Superspace Higher Derivative Terms in Two Dimensions

We study $(2,2)$ and $(4,4)$ supersymmetric theories with superspace higher derivatives in two dimensions. A characteristic feature of these models is that they have several different vacua, some of which break supersymmetry. Depending on the vacuum, the equations of motion describe different propagating degrees of freedom. Various examples are presented which illustrate their generic properties. As a by-product we see that these new vacua give a dynamical way of generating non-linear realizations. In particular, our 2D $(4,4)$ example is the dimensional reduction of a 4D $N=2$ model, and gives a new way for the spontaneous breaking of extended supersymmetry.Comment: 23 pages, v3: comments added, published versio

Experimental analysis of micro-cracks on the change of moisture transport properties of AAC

In this paper, series of experiment measurements is carried out in order to study effect of freeze/thaw loading on the change of moisture transport properties of autoclaved aerated concrete. The samples were subjected to 15, 30 and 45 freeze/thaw cycles and subsequently basic physical properties, pore size distribution and water vapor and liquid water transport properties were investigated. The results showed significant changes in material properties of the material. The results of this research can be further implemented into computational models in order to bring the simulation results closer to the reality

α-Fe2O3 nanoparticles/vermiculite clay material: Structural, optical and photocatalytic properties

Photocatalysis is increasingly becoming a center of interest due to its wide use in environmental remediation. Hematite (-Fe2O3) is one promising candidate for photocatalytic applications. Clay materials as vermiculite (Ver) can be used as a carrier to accommodate and stabilize photocatalysts. Two different temperatures (500 degrees C and 700 degrees C) were used for preparation of -Fe2O3 nanoparticles/vermiculite clay materials. The experimental methods used for determination of structural, optical and photocatalytic properties were X-ray fluorescence (ED-XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS), N-2 adsorption method (BET), diffuse reflectance UV-Vis spectroscopy (DRS), photoluminescence spectroscopy (PL) and photocatalytic reduction of CO2, respectively. The data from XRD were confronted with molecular modeling of the material arrangement in the interlayer space of vermiculite structure and the possibility of anchoring the -Fe2O3 nanoparticles to the surface and edge of vermiculite. Correlations between structural, textural, optical and electrical properties and photocatalytic activity have been studied in detail. The -Fe2O3 and -Fe2O3/Ver materials with higher specific surface areas, a smaller crystallite size and structural defects (oxygen vacancies) that a play crucial role in photocatalytic activity, were prepared at a lower calcination temperature of 500 degrees C.Web of Science1211art. no. 188

Partial N=2{\cal N}=2 Supersymmetry Breaking and Deformed Hypermultiplets

We study partial supersymmetry breaking from ${\cal N}=2$ to ${\cal N}=1$ by adding non-linear terms to the ${\cal N}=2$ supersymmetry transformations. By exploiting the necessary existence of a deformed supersymmetry algebra for partial breaking to occur, we systematically use ${\cal N}=2$ projective superspace with central charges to provide a streamlined setup. For deformed ${\cal O}(2)$ and ${\cal O}(4)$ hypermultiplets, besides reproducing known results, we describe new models exhibiting partial supersymmetry breaking with and without higher-derivative interactions.Comment: 49 pages, v

Photocatalytic oxidation of methyl tert-butyl ether in presence of various phase compositions of TiO2

MTBE (methyl tert-butyl ether) represents a rising threat to the environment, especially drinking water, and its effective removal (with all by-products) is necessary. Even a very low concentration of MTBE makes the water undrinkable; therefore, an effective treatment has to be developed. This work is focused on MTBE photocatalytic oxidation in presence of various TiO2 photocatalysts with different phase composition prepared by different methods. It was confirmed the phase composition of TiO2 had the most significant influence on the photocatalytic degradation of MTBE. The rutile phase more easily reduces adsorbed oxygen by photogenerated electrons to superoxide radical, supporting separation of charge carriers. The presence and concentrations of by-products have to be taken into account as well. The conversion of total organic carbon (TOC) was used for the comparison, 40% of TOC was removed after 1 h of irradiation in presence of TiO2-ISOP-C/800 photocatalyst composed of anatase and rutile phase.Web of Science101art. no. 3

Nástroje k analýze rázů

The paper deals with evaluation the shock response spectrum (SRS), which is employed to analysis of impulse signals. This kind of spectra is a set of the minimum or maximum values of the time response produced by the single degree-of-freedom (SDOF) system, which is tuned to a set of resonance frequencies, to a shock signal. The response is evaluated as an output of the second order infinite response filter (IIR) with an input, which is the sequence of the acceleration signal samples. The theory is illustrated by examples.Příspěvek pojednává o výpočtu rázového spektra, které je použito k analýze impulsních signálů. Tento druh spektra je složen z množiny maximálních nebo minimálních hodnot časových odezev na impulsní buzení, získaných ze soustavy s jedním stupněm volnosti, která je naladěná na množinu rezonančních frekvencí. Odezva je vypočtena jako výstup IIR filtru s impulsním signálem ve formě posloupnosti hodnot vzorků signálů zrychlení

Photocatalytic decomposition of nitrous oxide using TiO2 and Ag-TiO2 nanocomposite thin films

TiO2 and Ag-TiO2 (0.05, 0.25 and 1 wt% of Ag) thin films were prepared by the sol–gel method. The prepared films were characterized using SEM-EDAX, XRD, Raman spectroscopy, atomic force microscopy and UV–Vis spectrometry. Photocatalytic decomposition of N2O was performed in an annular batch reactor illuminated with an 8 W Hg lamp (254 nm wavelength). The photoreactivity of Ag-TiO2 increases with the Ag amount to 0.25 wt% Ag. Further increase of Ag loading to 1 wt% Ag did not change N2O conversion. The Ag particles deposited on the TiO2 surface can act as electron–hole separation centers. The presence of water vapor and oxygen in the reaction mixture slightly improved N2O conversion.Web of Science20917517

Thorax measurement and analysis using electrical impedance tomography

The article deals with a novel method of visualizing interior of an object based on the measurements made on the boundary. Although an electrical impedance tomography is well established in areas where reference measurement can be easily made (difference method), it is still rather a theoretical approach for areas where reference cannot be taken (mainly in medicine). We have made a thorax measurement using difference method. The results show that electrical impedance tomography can provide valuable information for thorax visualization