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[en] Full text: Thermal degradation behavior during polymer pyrolysis can typically be described using three apparent kinetic parameters (i.e., pre-exponential factor, activation energy, and reaction order). Several efficient techniques have been developed to estimate these apparent kinetic parameters for simple thermal degradation behavior (i.e., single apparent pyrolysis reaction). Unfortunately, these techniques cannot be directly extended to the case of polymer pyrolysis with complex thermal degradation behavior (i.e., multiple concurrent reactions forming single or multiple DTG peaks). In this work, we proposed a deconvolution method to determine the number of apparent reactions and estimate three apparent kinetic parameters and contribution of each reaction for polymer pyrolysis with complex thermal degradation behavior. The proposed technique was validated with the model and experimental pyrolysis data of several polymer blends with known compositions. The results showed that (1) the number of reaction and (2) three apparent kinetic parameters and contribution of each reaction can be estimated reasonably. The simulated DTG curves with estimated parameters also agree well with experimental DTG curves. (author)
[en] Autoradiographical analysis was used to investigate the radionuclides distribution in the process of thermal decontamination of asphalt. Cs-137 and Sr-90 were introduced in asphalt to simulate real contamination. It was found that penetration of these radionuclides is very small (about 1 mm). No significant emission of radionuclides was observed in the process of thermal decontamination
[en] It is a necessary that using mechanical structure such plant brings degradation. Especially corrosion environment under high temperature and high pressure, mechanical equipment makes error suddenly, so it stops operation or breaking. It has been responsible for major costs and unit outage time.
[en] It was determined that grain growth takes place during isothermal annealing of uranium metal fuel elements at 5500 C. The average grain size changes with annealing time according to a relationship of the type D= -0.003 t 2 + 0.995 t + D0. (author)
[en] Degradation in piezoelectric materials properties due to extensive electrical and thermal cycling is a common phenomenon, which some time alter their internal characteristics. The degradation in properties can affect the function and efficiency of instruments in which these materials are being used. Therefore, it becomes important to identify the extent of changes in performance when exposed to different types of solutions. A piezoelectric ceramic disc was exposed to 3 different solutions, ordinary water, de-ionized water and a solution of NaCl. The PZT (Lead Zirconate Titanate) was immersed in these solutions at 80 deg. C and performance characteristics recorded for different frequencies. After effects of the immersed disc due to three different solutions have been analyzed and it is observed that the PZT ceramic is sensitive to the type of water, but regains its original performance characteristics within short period of time. Thin PZT Disc after immersion in NaCl solution in regaining its maximum output voltage in longer period as compared to ordinary and de-ionized water. (author)
[en] Complete text of publication follows. Inulin-type fructans can be found in more than 36.000 plant species and they are among the most abundantly occurring carbohydrates in nature. Inulin is a linear chain of fructose monomers having a terminal glucose moiety with an average degree of polymerisation (DP) of 10. Major goal of our study was to develop a new, inulin-containing functional food (biscuit) with pronounced prebiotic impact. Application of novel analytical and microbiological methods aimed at revealing of both heat degradation pathway and the exact prebiotic impact of inulin. Dependency of microbiological activity on the time-interval of thermal treatment was examined in cases of E. coli, Bifidobacterium and Enterococcus. 12 min of treatment at 190 deg C was the most efficient in order to acquire the most pronounced prebiotic effect. 90% of the original amount of inulin has been decomposed leading to a new product (biscuit) with multiplicated bacterium activating effect. Comparison of distinctive extraction and sample preparation protocols has been performed. Throughout our studies inulin was acquired from Chicorium intybus L. (chicory), Dahlia species (dahlia), Helianthus tuberosus (Jerusalem artichoke), and the samples were treated at 8 different temperatures for 9 distinctive time periods. Thermal treatments were carried out from 150 deg C up to 230 deg C. Mapping of the thermal degradation of the inulin was accomplished by means of HPLC-ELS-MS technique. Oligo-, and polymers deriving from inulin's heat degradation were isolated ranging from DP3 up to DP31. Various fructan oligomer degradates were identified directly with the exact number of fructose units, thus the entire decomposition pathway was revealed. Thermal degradation of inulin results in the formation of degradates activating the Bifidobacterium species 5 times more than the non-treated inulin. Major output of our study is that a new functional foodstuff with enhanced prebiotic effect is produced by thermal treatment of inulin. The activation of relevant microbes was justified by test experiments.