Polydioxanone (PPDX), as an FDA approved polymer in tissue engineering, is an important component of some promising medical devices, e.g., biodegradable stents. The hydrolytic degradation of polydioxanone stents plays a key role in the safety and efficacy of treatment. A new fast and convenient method to quantitatively evaluate the hydrolytic degradation of PPDX stent material was developed. PPDX esophageal stents were degraded in phosphate-buffered saline for 24 weeks. For the first time, the changes in Raman spectra during PPDX biodegradation have been investigated here. The level of PPDX hydrolytic degradation was determined from the Raman spectra by calculating the area under the 1732 cm−1 peak shoulder. Raman spectroscopy, unlike Fourier transform infrared (FT-IR) spectroscopy, is also sensitive enough to monitor the decrease in the dye content in the stents during the degradation. Observation by a scanning electron microscope showed gradually growing cracks, eventually leading to the stent disintegration. The material crystallinity was increasing during the first 16 weeks, suggesting preferential degradation of the amorphous phase. Our results show a new easy and reliable way to evaluate the progression of PPDX hydrolytic degradation. The proposed approach can be useful for further studies on the behavior of PPDX materials, and for clinical practice.

We experimentally demonstrate that the statistical properties of distances between pedestrians which are hindered from avoiding each other are described by the Gaussian Unitary Ensemble of random matrices. The same result has recently been obtained for an n-tuple of non-intersecting (one-dimensional, unidirectional) random walks. Thus, the observed behavior of autonomous walkers conditioned not to cross their trajectories (or, in other words, to stay in strict order at any time) resembles non-intersecting random walks.

Biodegradable biliary stents are promising treatments for biliary benign stenoses. One of the materials considered for their production is polydioxanone (PPDX), which could exhibit a suitable degradation time for use in biodegradable stents. Proper material degradation characteristics, such as sufficient stiffness and disintegration resistance maintained for a clinically relevant period, are necessary to ensure stent safety and efficacy. The hydrolytic degradation of commercially available polydioxanone biliary stents (ELLA-CS, Hradec Králové, Czech Republic) in phosphate-buffered saline (PBS) was studied. During 9 weeks of degradation, structural, physical, and surface changes were monitored using Raman spectroscopy, differential scanning calorimetry, scanning electron microscopy, and tensile and torsion tests. It was found that the changes in mechanical properties are related to the increase in the ratio of amorphous to crystalline phase, the so-called amorphicity. Monitoring the amorphicity using Raman spectroscopy has proven to be an appropriate method to assess polydioxanone biliary stent degradation. At the 1732 cm−1 Raman peak, the normalized shoulder area is less than 9 cm−1 which indicates stent disintegration. The stent disintegration started after 9 weeks of degradation in PBS, which agrees with previous in vitro studies on polydioxanone materials as well as with in vivo studies on polydioxanone biliary stents.

Tightening of norms for air protection leads to a development of new and significantly more effective techniques for removing particulate matter, SOx and NOx from flue gas which originates from large solid fuel combustion. Recently, it has been found that combinations of these environmental technologies can also lead to the reduction of mercury emissions from coal power plants. Now the greatest attention is paid especially to the coal power plant in Opatovice nad Labem, close to Hradec Kralove. Its system for flue gas dedusting was replaced by a modern type of cloth fabric filter with the highest particle separation efficiency which belongs to the category of BAT. Using this technology, together with modernization of the desulphurisation device and increasing of nitrogen oxides removal efficiency, leads also to a reduction of mercury emissions from this power plant. The University of Hradec Kralove, the Opole University and EMPLA Hradec Kralove successfully cooperate in the field of toxic metals biomonitoring almost 20 years. In the Czech-Polish border region, comprehensive biomonitoring of mercury in bioindicators Xerocomus badius in 9 long-term monitored reference points is done. The values of mercury concentration measured in 2012 and 2016 were compared with values computed by a dispersion model SYMOS´97 (updated 2014). Thanks to modern methods of dedusting and desulphurisation, emissions of mercury from this large coal power plant are now smaller than before and that the downward trends continues. The results indicate that Xerocomus badius is a suitable bioindicator for a long-term monitoring of changes in mercury imissions in this forested border region. This finding is significant because it shows that this region is suitable for leisure, recreation, and rehabilitation.

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