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21.
Formation of PCDD/Fs from the copper oxide-mediated pyrolysis and oxidation of 1,2-dichlorobenzene 总被引:1,自引:0,他引:1
Formation of polychorinated dibenzo-p-dioxins (PCDDs) has been demonstrated to occur via surface-mediated reactions of chlorinated phenols. However, polychlorinated dibenzofurans (PCDFs) are observed in much lower yields in laboratory studies than in full-scale combustors where PCDFs are in higher concentrations than PCDDs. This has led to the suggestion that at least PCDFs are formed from elemental carbon in the de novo process. However, the potential for PCDF formation from reactions of chlorinated benzenes has been largely overlooked. In this study, we investigated the potential contribution of chlorinated benzenes to formation of PCDD/Fs using 1,2-dichlorobenzene as a surrogate for reactions of other chlorinated benzenes and CuO/silica (3 wt % Cu) as a surrogate for fly ash. Results were similar for oxidative and pyrolytic conditions with a slight increase in more chlorinated products under oxidative conditions. Reaction products included chlorobenzene, polychlorinated benzenes, phenol, 2-monochlorophenol (2-MCP), dichlorophenols, and trichlorophenols with yields ranging from 0.01 to 2% for the phenols and from 0.01 to 10% for chlorinated benzenes. 4,6-Dichlorodibenzo furan (4,6-DCDF) and dibenzofuran (DF) were observed in maximum yields of 0.2% and 0.5%, respectively, under pyrolytic conditions and 0.1% and 0.3%, respectively, under oxidative conditions. In previous studies of the pyrolysis of 2-MCP under identical conditions, 4,6-DCDF and dibenzo-p-dioxin (DD) were observed with maximum yields of ~0.2% and ~0.1%, respectively, along with trace quantities of 1-monochlorodibenzo-p-dioxin (1-MCDD). Under oxidative conditions, 1-MCDD, DD, and 4,6-DCDF were observed with maximum yields of 0.3%, 0.07% and 0.1%, respectively. When combined with the fact that measured concentrations of chlorinated benzenes are 10-100× that of chlorinated phenols in full-scale combustion systems, the data suggest surface-mediated reactions of chlorinated benzenes can be a significant source of PCDD/F emissions. 相似文献
22.
Marcin Pastorczak Michael Wübbenhorst Gustavo Dominguez-Espinosa Lidia Okrasa Marek Pyda Marcin Kozanecki Slawomir Kadlubowski Piotr Ulanski Janusz M. Rosiak Jacek Ulanski 《Polymer》2012,53(1):161-168
The phase transition observed by various methods in poly(vinyl methyl ether)/water systems at around 18 °C has been assigned by some investigators to the pre-melting of water and by others to a glass transition of the polymer. In this study, broadband dielectric spectroscopy and temperature modulated differential scanning calorimetry were used to identify this transition in radiationally crosslinked poly(vinyl methyl ether) hydrogels, as well as to analyse sub-zero relaxation processes in such a three-phase (polymer/ice/liquid water) system. The process at 18 °C was related to the pre-melting of water induced by the segmental motions of the polymer; however, it was seen to be one transition due to the cooperative motions of both compounds. The atypical (two regimes) temperature dependence of the segmental motion process was observed and was related to confinement of the polymer chains between ice clusters below approximately ?24 °C; furthermore, the main dielectric process of hexagonal ice was identified and a Maxwell-Wagner effect was observed. 相似文献
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24.
Chunbao Li Slawomir Szczepaniak Liselot Steen Olivier Goemaere Sandra Impens Hubert Paelinck Guanghong Zhou 《International Journal of Food Science & Technology》2011,46(10):2159-2163
This study evaluates effect of tumbling time and cooking temperature on cooking rate, cooking loss (CL), colour, water activity and water‐holding capacity of cooked restructured ham rolls. In experiment were investigated three tumbling times (2, 4 and 6 h) at constant temperature (+4 °C) and three cooking temperatures (76, 86 and 96 °C). It was observed that CL decreased (P < 0.01) from 5.41% to 3.22% with tumbling time (2 h vs. 6 h) but increased (P < 0.01) from 2.35% to 7.25% along with cooking temperature (76 °C vs. 96 °C). In contrast, pH value increased (P < 0.01) from 6.18 to 6.24 with tumbling time (2 h vs. 6 h) but decreased (P < 0.01) from 6.22 to 6.17 along with cooking temperature (76 °C vs. 96 °C). In addition, high temperature had higher efficiency for thermal lethality than low temperature (F0 values were 19 and 92 min at 96 and 76 °C, respectively). Intermediate tumbling (4 h) and cooking (86 °C) could be preferential. 相似文献
25.
Rika E. Anderson Alexis D. Ostrowski Danielle E. Gran Jesse D. Fowler Alan R. Hopkins Randy M. Villahermosa 《Polymer Bulletin》2008,61(5):563-568
Summary Various diameters of polyaniline (PANI) nanofibers were easily made by varying the sweep rate in the
electrochemical polymerization of the aniline monomer. At a sweep rate of 5 mV/s, the PANI nanofibers have
an average diameter of 450 nm with a median of 440 nm. The fibers are short, on the order of a few microns
in length, and exhibit a branched geometry. Increasing the sweep rate to 50 mV/s produced longer nanofibers
with a smaller average diameter of 200 nm. Nanofibers synthesized at 100 mV/s were noted to be smaller
with an average and median diameter of 100 nm. These results illustrate the ease in which the morphology
of nanostructured PANI can be altered and indicate that the method has the potential to create multi-diameter
fibers or mixed-morphology materials. 相似文献
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28.
Slawomir Koziel Adrian Bekasiewicz 《International Journal of Numerical Modelling》2016,29(6):1028-1035
One of the important prerequisites for efficient design optimization of microwave structures is availability of fast yet reliable replacement models (surrogates) so that multiple evaluations of the structure at hand can be executed in reasonable timeframe. Direct utilization of full‐wave electromagnetic (EM) simulations for handling optimization‐related tasks is often prohibitive. A popular approach to construction of fast surrogates is data‐driven modeling. Unfortunately, it normally requires a large number of training samples, and it is virtually infeasible for structures that exhibit highly nonlinear responses (e.g. filters or couplers). In this work, a design‐oriented modeling technique is proposed where good accuracy is achieved by careful non‐uniform design space sampling that accounts for nonlinear relationship between the operating frequency of the structure and its geometry parameters, as well as carrying out the modeling process only for selected characteristic points of the structure responses (those that determine satisfaction/violation of given design specifications). Our approach is demonstrated using a miniaturized microstrip rat‐race coupler modeled in a wide range of geometry parameters and compared to conventional data‐driven modeling using kriging interpolation. Design optimization examples are also provided. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
29.
Katarzyna M. Terlikowska Anna M. Witkowska Malgorzata E. Zujko Bozena Dobrzycka Slawomir J. Terlikowski 《International journal of molecular sciences》2014,15(12):21703-21722
Recent findings on the molecular basis of ovarian cancer development and progression create new opportunities to develop anticancer medications that would affect specific metabolic pathways and decrease side systemic toxicity of conventional treatment. Among new possibilities for cancer chemoprevention, much attention is paid to curcumin—A broad-spectrum anticancer polyphenolic derivative extracted from the rhizome of Curcuma longa L. According to ClinicalTrials.gov at present there are no running pilot studies, which could assess possible therapeutic benefits from curcumin supplementation to patients with primary epithelial ovarian cancer. Therefore, the goal of this review was to evaluate potential preclinical properties of curcumin and its new analogues on the basis of in vivo and in vitro ovarian cancer studies. Curcumin and its different formulations have been shown to display multifunctional mechanisms of anticancer activity, not only in platinum-resistant primary epithelial ovarian cancer, but also in multidrug resistant cancer cells/xenografts models. Curcumin administered together with platinum-taxane chemotherapeutics have been reported to demonstrate synergistic effects, sensitize resistant cells to drugs, and decrease their biologically effective doses. An accumulating body of evidence suggests that curcumin, due to its long-term safety and an excellent profile of side effects should be considered as a beneficial support in ovarian cancer treatment strategies, especially in patients with platinum-resistant primary epithelial recurrent ovarian cancer or multidrug resistant disease. Although the prospect of curcumin and its formulations as anticancer agents in ovarian cancer treatment strategy appears to be challenging, and at the same time promising, there is a further need to evaluate its effectiveness in clinical studies. 相似文献
30.
Dawid Janas Stefanie K. Kreft Slawomir Boncel Krzysztof K. K. Koziol 《Journal of Materials Science》2014,49(20):7231-7243
We devised a simple and effective method of electrochemical functionalization of horizontally aligned CNT films in diluted HCl and H2SO4 solutions upon their electrolysis under a constant current mode. We were able to cause notable generation of carbon–oxygen and carbon–chlorine functional groups on the CNT film anodes as proven by EDX, XPS, and Raman spectroscopy. As a consequence, we observed significant changes of the morphology of the material under electron microscopy, what translated into improved compatibility of CNTs with hydrophilic media. In turn, application of CNT films as cathodes was found as a powerful tool for a thorough cleaning of the nanotubes. Finally, we demonstrated that by the selection of appropriate conditions, CNT films can act as easy-to-make and flexible electrodes with a high stability and performance superior to graphite for generation of non-oxidizing gases such as hydrogen from solution. CNT film electrodes are two orders of magnitude lighter and require much lower overpotential for faradaic splitting of water. 相似文献