Brno University of Technology

About: Brno University of Technology is a education organization based out in Brno, Czechia. It is known for research contribution in the topics: Computer science & Fracture mechanics. The organization has 6339 authors who have published 15226 publications receiving 194088 citations. The organization is also known as: Vysoké učení technické v Brně & BUT.

Light scattering on PHA granules protects bacterial cells against the harmful effects of UV radiation.

Abstract: Numerous prokaryotes accumulate polyhydroxyalkanoates (PHA) in the form of intracellular granules. The primary function of PHA is the storage of carbon and energy. Nevertheless, there are numerous reports that the presence of PHA granules in microbial cells enhances their stress resistance and fitness when exposed to various stress factors. In this work, we studied the protective mechanism of PHA granules against UV irradiation employing Cupriavidus necator as a model bacterial strain. The PHA-accumulating wild type strain showed substantially higher UV radiation resistance than the PHA non-accumulating mutant. Furthermore, the differences in UV-Vis radiation interactions with both cell types were studied using various spectroscopic approaches (turbidimetry, absorption spectroscopy, and nephelometry). Our results clearly demonstrate that intracellular PHA granules efficiently scatter UV radiation, which provides a substantial UV-protective effect for bacterial cells and, moreover, decreases the intracellular level of reactive oxygen species in UV-challenged cells. The protective properties of the PHA granules are enhanced by the fact that granules specifically bind to DNA, which in turn provides shield-like protection of DNA as the most UV-sensitive molecule. To conclude, the UV-protective action of PHA granules adds considerable value to their primary storage function, which can be beneficial in numerous environments.

Pt-loaded Al2O3 catalytic filters for screen-printed WO3 sensors highly selective to benzene

Abstract: We describe the fabrication of low-cost benzene sensors by using screen-printing technology. Two different types of catalytic filters were developed to enhance the sensitivity of tungsten oxide films to benzene. The first type of filter consists of a porous Al 2 O 3 layer, loaded with a Pt layer on its surface. The second type of filter is based on a porous Al 2 O 3 layer, with Pt homogeneously distributed in its bulk. These filters were used to coat WO 3 -based sensors. The presence of by-products resulting from the incomplete catalytic combustion of benzene in the catalytic filters (that could further interact with the WO 3 film), explains the higher sensitivity of the coated sensors, as compared with the sensitivity of bare tungsten oxide sensors. In particular, it is shown that a very selective benzene sensor can be obtained by combining a coated and uncoated tungsten oxide sensor. This combined sensor, selectively detects benzene in a wide concentration range in the presence of interfering species such as ethanol, ammonia, nitrogen dioxide and water vapour.

Probabilistic linear discriminant analysis of i-vector posterior distributions

Abstract: The i-vector extraction process is affected by several factors such as the noise level, the acoustic content of the observed features, and the duration of the analyzed speech segment. These factors influence both the i-vector estimate and its uncertainty, represented by the i-vector posterior covariance. This paper present a new PLDA model that, unlike the standard one, exploits the intrinsic i-vector uncertainty. Since short segments are known to decrease recognition accuracy, and segment duration is the main factor affecting the i-vector covariance, we designed a set of experiments aiming at comparing the standard and the new PLDA models on short speech cuts of variable duration, randomly extracted from the conversations included in the NIST SRE 2010 female telephone extended core condition. Our results show that the new model outperforms the standard PLDA when tested on short segments, and keeps the accuracy of the latter for long enough utterances. In particular, the relative improvement is up to 13% for the EER, 5% for DCF08, and 2.5% for DCF10.