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101.
Oligocarbonate diols due to their resistance to oxidation and hydrolysis are particularly valuable components of polyurethanes for biomedical applications. It was shown that for their synthesis “green monomer,” ethylene carbonate can be used in the reaction with 1,6‐hexanediol, instead of usually applied toxic and harmful phosgene. Depending on reaction conditions, besides ester exchange leading to the desired product, competitive etherification is often observed. To optimize the reaction conditions leading to oligocarbonates of high molecular weight without oxyethylene fragments, the method of an experimental design was applied. Such approach enabled the estimation of the influence of reaction temperature, ethylene carbonate to 1,6‐hexanediol molar ratio and catalyst (NaCl) concentration on the molar mass of oligocarbonate diol, content of ether bonds and reaction time. Application of central composite method as an experimental design allowed not only to choose the optimal set of conditions, but also the coefficients of the regression equation were interpreted in a chemical way. Oligocarbonate diols obtained under optimal conditions were used for synthesis poly(urethane‐urea)s which exhibited very good mechanical properties (tensile strength 45–50 MPa and elongation at break up to 500%). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
102.
103.
Sławomir Wybraniec Karolina Starzak Anna Skopińska Maciej Szaleniec Jacek Słupski Katarzyna Mitka Piotr Kowalski Tadeusz Michałowski 《Food science and biotechnology》2013,22(2):353-363
An effect of metal cations on betanin stability was investigated in aqueous and organic-aqueous solutions. The presence of organic solvents (methanol, ethanol, and acetonitrile) affects substantially the pigments decomposition in acidic media induced by metal cations whose degrading action in such media is significantly higher than in aqueous solutions. The influence of Cu2+ on the stability was studied by spectrophotometry in more detailed manner, because of its ability to form complexes with betanin. The possibility of a complex formation between betanin and Ni2+ was also stated at pH 7–8; its relatively high stability in aqueous samples was observed. A presence of numerous products of betanin decomposition was detected in the wavelength range 380–500 nm in spectra obtained for most of metal cations investigated, especially for higher concentrations of the organic solvents. 相似文献
104.
An investigation was carried out to build an adequate but economical system for monitoring small landscape elements in The Netherlands. Many organizations concerned with landscape management and policy support such a system as an aid to stop the deterioration of the landscape. The designed monitoring system was tried out in three areas with different landscape types. Results showed that the system can answer a lot of questions about the development of landscape quality. With the aid of local volunteers the monitoring system is economical. 相似文献
105.
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
106.
107.
Christina Wildfire Engin Çiftyürek Katarzyna Sabolsky Edward M. Sabolsky 《Journal of Materials Science》2014,49(14):4735-4750
The incorporation of selective nanomaterials, such as common metal oxide semiconductor compositions, into resistive-type gas sensors has been shown by many researchers to lead to very high sensitivities and response rates, especially for micro-sized chemical sensors for room-temperature applications. The same strategy utilizing sensing nanomaterials has not been demonstrated for high-temperature sensors due to the intrinsic instability of typical metal oxide semiconductor nanomaterials at temperatures >500 °C. Within this work, doped Gd2Zr2O7 (GZO) nanomaterial compositions were investigated for H2 resistive-type sensors for applications between 600 and 1000 °C. This paper investigates the mechanism of H2 sensing for doped GZO nanomaterials and SnO2/GZO nanocomposites at the elevated temperatures. By integrating 10 vol.% nano-SnO2 into yttrium-doped GZO nanomaterials, a sensitivity of 4.15 % was retained for 4000 ppm H2 levels with a low signal drift of 0.42 %/h at 1000 °C in a 20 % O2/N2 gas stream. The signal drift was reduced by more than half of that compared to pure nano-SnO2 at the same conditions. The nano-GZO limited the grain growth of the nano-SnO2 particles and also prevented the nano-SnO2 from fully reducing to Sn at high temperatures in a low oxygen atmosphere. It is among the first resistive-type sensors operating at 1000 °C with sensing times of <5 min. This demonstration provided an example of a strategy of combining traditional metal oxide semiconductor and refractory nanomaterial compositions to form sensing nanocomposites with new sensing mechanisms, as well as, enhanced chemical and microstructural stabilities in high-temperature environments. 相似文献
108.
Carminna Ottone Vivian Farías Rivera Marco Fontana Katarzyna Bejtka Barbara Onida Valentina Cauda 《材料科学技术学报》2014,30(12):1167-1173
Highly mesoporous Zn O and g-Al2O3nanowires(NWs) are both synthesized by a hydrothermal method using commercially available porous anodic aluminium oxide(AAO) as template. AAO membrane acts as template for Zn O NWs and both as template and precursor for g-Al2O3 NWs. The formation of intermediate phases of porous Zn6Al2(OH)16CO3and boehmite(g-Al OOH) were observed, both occurring during the hydrothermal synthesis of porous Zn O and g-Al2O3 NWs, respectively, and disappearing after annealing at 600 C. This novel template-assisted hydrothermal process leads to the formation of porous Zn O and g-Al2O3NWs(specific surface area of 192 m2 g 1and 263 m2 g 1, respectively), showing pore sizes around 4 nm in diameter. The influence of the reaction parameters on the nanostructure morphology was also investigated. A Zn O seed layer, deposited on the AAO channels prior to the hydrothermal synthesis, leads to more compact Zn O nanowires(99 m2 g-1) protecting the AAO host from the chemical attack of the precursor solution. 相似文献
109.
Katarzyna Wykpis Magdalena Popczyk Antoni Budniok 《Bulletin of Materials Science》2011,34(4):997-1001
Zn-Ni coatings were deposited under galvanostatic conditions on steel substrate (OH18N9). The influence of current density
of deposition on the surface morphology, chemical and phase composition was investigated. The corrosion resistance of Zn-Ni
coatings obtained at current density 10–25 mA cm−2 are measured, and are compared with that of metallic cadmium coating. Structural investigations were performed by the X-ray
diffraction (XRD) method. The surface morphology and chemical composition of deposited coatings were studied using a scanning
electron microscope (JEOL JSM-6480) with EDS attachment. Studies of electrochemical corrosion resistance were carried out
in the 5% NaCl, using potentiodynamic and electrochemical impedance spectroscopy (EIS) methods. On the ground of these research,
the possibility of deposition of Zn-Ni coatings contained 24–26% at. Ni was exhibited. It was stated, that surface morphology,
chemical and phase composition of these coatings are practically independent on current density of deposition. On the basis
of electrochemical investigations it was found that corrosion resistance of these Zn-Ni coatings is also independent of current
density. These coatings are more corrosion resistant in 5% NaCl solution than metallic cadmium. It was suggested that the
Zn-Ni coating may be used as a substitute for toxic cadmium. 相似文献
110.
Marcin ?roda Katarzyna Cholewa-KowalskaMarek Ró?ański Marek Nocuń 《Optical Materials》2011,33(3):397-401
Glasses of different matrix (phosphate, borate, silicate and lead-silicate) were studied for their optical properties. The effect of Er dopant on transmittance and luminescence properties was presented. The significant “red shift” and “blue shift” of UV edge absorption were discussed based on the changes in the framework of the borate and phosphate glasses, respectively. It was showed that the integral intensity of the two main optical absorption transitions monotonically increases with the order: phosphate < borate < silicate < lead-silicate. Ellipsometric measurement was applied to obtain the refractive index of the glasses. The correlation between the shift of edge absorption and the change of refractive index was presented. Effect of glassy matrix on luminescence of Er3+ was discussed. 相似文献