The purpose of this study was to test the hypothesis that more recently developed rubber dam systems (OptraDam ® Plus and OptiDam™) are faster and easier to handle, and that the quality of isolation is not decreased. The rubber dam systems were applied in standard conditions on a dental simulator in several model clinical situations. The time of preparation, application and removal were measured and the quality of isolation was evaluated. The median time of rubber dam placement was 51 s (Q1 = 38 s; Q3 = 79 s). The shortest median time of application was with OptiDam™ (42 s), followed by a conventional rubber dam (53 s), and finally the longest was with OptraDam® Plus (58 s). The median volume of fluid remaining in the isolated space after 5 minutes was 9.5 mL (Q1 = 8 mL; Q3 = 10 mL). The largest median volume of remaining water was with OptiDam™ (10 mL), followed by a conventional rubber dam (9.5 mL) and the least with OptraDam® Plus (8.5 mL). The afore-stated hypothesis about the advantages of modern rubber dam isolation systems was accepted for OptiDam™, but rejected for OptraDam® Plus. The results could contribute to decision-making concerning the choice of rubber dam system. and Martin Kapitán, Zdeňka Šustová, Romana Ivančaková, Jakub Suchánek
Hluk patří v dnešní době k nejrozšířenějším škodlivinám životního prostředí a způsobuje závažná civilizační onemocnění. V současné době v ČR nejsou známy v dostatečné míře relevantní poznatky o hlučnosti jednotlivých typů povrchů vozovek a jejích změnách. Předkládaný článek se zabývá měřením povrchů vozovek metodou malé vzdálenosti (CPX) dle návrhu normy ISO 11819-2. Proto jsou podrobně diskutovány jednotlivé aspekty, jež mají v různé míře na vlastní měření v terénu vliv. Představeny jsou dílčí výsledky získané v rámci projektu TAČR č. TA01030459 – "Změna hluku povrchů vozovek v průběhu několika let používání", které mají poskytnout základní informace o hladinách akustického tlaku A styku pneumatika/vozovka různých typů i stáří povrchů vozovek používaných na území ČR. Výsledky potvrzují, že specializované "nízkohlučné povrchy" mohou přispět ke snižování nadměrné hlukové zátěže ze silniční dopravy, ovšem je velmi důležité provádět měření v souladu s doporučením nejnovějších norem a u prezentovaných výsledků sledovat, jaká je zvolena srovnávací základna pro porovnání mezi běžným a "nízkohlučným" povrchem., Nowadays, noise ranks among the most common pollutants of the environment and causes serious civilization-linked diseases. In the Czech Republic, relevant information on the noise level of individual road surfaces and their changes are currently largely unavailable. The present article deals with the measurement of road surfaces by Close ProXimity method (CPX) in accordance with the draft of standard ISO 11819-2. Therefore, individual aspects, which have different impacts on field measurement, are discussed in detail. Partial results obtained within a project of TAČR No. TA01030459 – "Change in the noise of road surfaces over several years of use" are presented. They are to provide basic information on the levels of acoustic pressure and the interface tyre/road of different road surface types and age used in the Czech Republic. The results confirm that specialized "low-noise surfaces" may help to reduce excessive noise from road transport, but it is necessary to perform measurements in compliance with recommendations from the latest standards, and to monitor the presented results regarding selected comparison bases for a comparison between common and "low-noise" surfaces., Vítězslav Křivánek, Rudolf Cholava, Karel Effenberger, and Literatura
Sdělení představuje souhrn aktuálních znalostí o fotokatalytickém jevu na povrchu nanočástic TiO2, přehled publikovaných sdělení o jejich známých a potenciálních zdravotních účincích, o biocidním působení i o možném využití v oblastí zlepšení kvality životního prostředí. Součástí je i přehledná diskuze reklamních tvrzení producentů nátěrů obsahujících nanočástice TiO2., Presented is a summary of current knowledge about the photocatalytic effect on the surface of TiO2 nanoparticles, review of published information and documents about the potential health effects, about their biocidal activity and about possible use of photocatalysis in improving the quality of the environment. It also includes a transparent discussion on advertising claims of producers of paints containing nanoforms TiO2., Bohumil Kotlík, Lenka Škrabalová, Lenka Šubčíková, and Literatura
INTRODUCTION: The aim of this study was to find out the impact of degradation and regeneration of force over time at NiTi springs on the value and course of the final acting force and to verify the possibility of using these phenomena for a directed transition to the reverse plateau and its maintaining. METHODS: Static and cyclic mechanical loadings were performed. At first unused springs were tested. Afterwards the springs were mechanically stabilized by stress cycling and finally tested again. The difference in shape of the working curves was assessed. For simulation and description of the force degradation the modified Voight model was used. RESULTS: New springs, mainly those with large hysteresis, showed a significant stress-strain curve movement and shape changes during the cycling. The effect of the stress-strain curve course change disappeared fully in the stabilized springs. Multiple loading led to an overall decrease of force value during the measurement. The effect of force degradation and regeneration over time by simple static loading varies in the range of percentage of the nominal force in the plateau area. The transition between stress-strain curve phases caused by the degradation or regeneration of the force wasn't observed in case of mechanically stabilized springs. CONCLUSIONS: Springs should be mechanically stabilized before their application. The degree of force degradation over time is insignificant for mechanically stabilized springs. Degradation or regeneration of force over time, mechanical stabilization or micromovements in the mouth don't cause any transition between individual stress-strain curve phases. and A. Bezrouk, L. Balský, M. Smutný, T. Nosek, J. Záhora, J. Hanus, R. Polma