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排序方式: 共有1103条查询结果,搜索用时 62 毫秒
991.
Katarzyna Waszkowiak 《International Journal of Food Science & Technology》2008,43(8):1437-1442
In the research the activity of rosemary extract introduced using connective tissue proteins was investigated, taking into consideration the effect of the type of carrier (collagen and elastin), carrier concentration (1%, 2%, 4%) and the method of its introduction to fat substrate (rehydrated or unhydrated). Antioxidative activity was assessed using the Oxidograph instrumental test. The activity of rosemary extract on protein preparations was significantly affected by the rehydration of these preparations. The application of collagen as carrier of rosemary extract had an advantageous effect on the activity of this antioxidant. In turn, under the adopted testing conditions the application of elastin resulted in partial masking of antioxidative activity of rosemary extract. Amounts of the carriers, onto which the antioxidant was introduced, did not have a statistically significant effect on this activity. 相似文献
992.
Agnieszka Cydzik‐Kwiatkowska Irena Wojnowska‐Baryła Katarzyna Selewska 《European Journal of Lipid Science and Technology》2010,112(5):609-613
The aim of the research was to evaluate the possibility of using the crude glycerol fraction from biodiesel manufacturing processes for granular sludge production. The experiment was carried out simultaneously in four sequencing batch reactors (SBRs) at different carbon loads: 0.2 ± 0.08, 0.6 ± 0.16, 1.1 ± 0.27, and 1.3 ± 0.35 g COD/g TSS per cycle (COD – chemical oxygen demand, TSS – total suspended solids). Granulation did not occur in the reactor with the lowest organic carbon load. In the remaining reactors small granules began to appear after 25 cycles of reactor operation. In all reactors the efficiency of carbon removal remained at ca. 80%. The highest granular sludge production per cycle was 0.31 ± 0.28 g TSS/L; it was obtained at an organic load of 1.1 ± 0.27 g COD/g TSS per cycle. Most of the introduced COD was removed in the reactors during the first 5 h of aeration; the COD removal rate was correlated with the organic load and varied from 123.12 to 472.76 mg COD per litre and hour. Practical applications: With the increasing production of biodiesel fuel a problem arises with the utilization of glycerol that is a by‐product of the process. By‐product glycerol fraction from small agricultural installations is usually contaminated. Its composition varies depending on parameters of the transesterification process and it is unprofitable to purify it. In the present research we investigated one possible way of dealing with the by‐product. The glycerol fraction was successfully used as a carbon source for the production of aerobic granular sludge. The granules obtained can be used as a seed sludge in granule‐based reactors, or can be cofired with coal or directly combusted. Since aerobic granular sludge is one of the most promising technologies investigated during the last few years it appears to possess high utility. 相似文献
993.
Thin alumina coatings containing zirconia or alumina nanoparticles having diameter of ~20–30 nm were deposited by the sol–gel dip-coating process on silicon wafers. The mass content of nanoparticles in the alumina coating was fixed at 15% in relation to the theoretical mass of alumina matrix resulted from the amount of the applied precursor. Atomic force microscopy (AFM) was used to image the surface topography of as-made coatings and find out the wear level after frictional tests. Tribological tests were performed with the use of a microtribometer operating in the load range of 30–100 mN. It was found that the presence of α-alumina (corundum) or zirconia nanoparticles enhances the tribological performance of alumina layers annealed at 100 °C by decreasing the average wear rate by 20% and 63% for zirconia and corundum nanoparticles, respectively. No wear was observed for samples containing both types of nanoparticles annealed at 500 °C. 相似文献
994.
Katarzyna Kosek-SzottAuthor Vitae 《Ad hoc Networks》2012,10(3):635-660
Ad-hoc networks suffer from the problem of hidden nodes (terminals), which leads to severe degradation of network throughput. This survey gives a comprehensive overview of Medium Access Control (MAC) protocols which directly or indirectly address this problem. The presented protocols are grouped in several categories and are described in the order of their publication date. To give the reader a deep understanding of the progress made in the area of alleviating the hidden node problem a brief summary of the key ideas as well as a detailed comparison of different protocols are presented. Open research directions are also discussed to serve as a starting point for future protocol design and evaluation. 相似文献
995.
Katarzyna Białowicz Krzysztof Mazurek Urszula Kiełkowska Mieczysław Trypuć 《Chemical Engineering Communications》2013,200(12):1467-1475
Investigation was carried out on the optimal conditions of the synthesis of KVO3 and Cl2 from KCl and V2O5 in the presence of atmospheric oxygen. The influence of the excess of KCl relative to V2O5 was investigated. Also, the effect of quartz sand introduced into the reaction mixture on the yield of KVO3 synthesis was determined. The obtained product of synthesis was isolated from the post-reaction mixture. 相似文献
996.
Diana Mańko Katarzyna Szymczyk Bronisław Jańczuk 《Journal of Adhesion Science and Technology》2013,27(11):1081-1095
The measurements of the contact angle of the aqueous solutions of TX-100 and TX-165 mixture with propanol on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) were carried out. On the basis of the obtained results, the dependence between the cosine of contact angle and surface tension as well as between the adhesion and surface tension of the solutions in the light of the work of adhesion of the solutions to the PTFE and PMMA surface was discussed. The dependence between the adhesion and surface tension for PMMA was correlated to the surface concentration of propanol as well as TX-100 and TX-165 mixture concentration determined from the Frumkin equation at the PMMA-air, PMMA-solution and solution–air interfaces. For this purpose, the surface tension of PMMA covered by a surface active agent film was determined using the Neumann et al. equation and next the PMMA–solution interface tension was evaluated from the Young equation. The values of the surface tension of PMMA covered by propanol and surfactants mixture layer were applied to describe the changes of the adhesion work of solutions to PMMA surface as a function of propanol and surfactants mixture concentration. The adhesion work of the aqueous solutions of TX-100 and TX-165 mixture with propanol to the PTFE and PMMA surfaces was discussed in the light of the adhesion work of particular components of the solutions. On the basis of the results obtained from the contact angle measurements, the standard Gibbs free energy of adsorption of particular components of solution was also considered. 相似文献
997.
Wojciech Bocian Beata Naumczuk Magdalena Urbanowicz Jerzy Sitkowski Anna Bierczyska-Krzysik Elbieta Bednarek Katarzyna Wiktorska Magorzata Milczarek Lech Kozerski 《International journal of molecular sciences》2021,22(14)
The compounds 7-ethyl-9-(N-methylamino)methyl-10-hydroxycamptothecin (2) and 7-ethyl-9-(N-morpholino)methyl-10-hydroxycamptothecin (3) are potential topoisomerase I poisons. Moreover, they were shown to have favorable anti-neoplastic effects on several tumor cell lines. Due to these properties, the compounds are being considered for advancement to the preclinical development stage. To gain better insights into the molecular mechanism with the biological target, here, we conducted an investigation into their interactions with model nicked DNA (1) using different techniques. In this work, we observed the complexity of the mechanism of action of the compounds 2 and 3, in addition to their decomposition products: compound 4 and SN38. Using DOSY experiments, evidence of the formation of strongly bonded molecular complexes of SN38 derivatives with DNA duplexes was provided. The molecular modeling based on cross-peaks from the NOESY spectrum also allowed us to assign the geometry of a molecular complex of DNA with compound 2. Confirmation of the alkylation reaction of both compounds was obtained using MALDI–MS. Additionally, in the case of 3, alkylation was confirmed in the recording of cross-peaks in the 1H/13C HSQC spectrum of 13C-enriched compound 3. In this work, we showed that the studied compounds—parent compounds 2 and 3, and their potential metabolite 4 and SN38—interact inside the nick of 1, either forming the molecular complex or alkylating the DNA nitrogen bases. In order to confirm the influence of the studied compounds on the topoisomerase I relaxation activity of supercoiled DNA, the test was performed based upon the measurement of the fluorescence of DNA stain which can differentiate between supercoiled and relaxed DNA. The presented results confirmed that studied SN38 derivatives effectively block DNA relaxation mediated by Topo I, which means that they stop the machinery of Topo I activity. 相似文献
998.
Thakur Raghu Raj Singh Martin J. Garland Katarzyna Migalska Ester Caffarel Salvador Rahamatullah Shaikh Helen O. McCarthy A. David Woolfson Ryan F. Donnelly 《应用聚合物科学杂志》2012,125(4):2680-2694
We characterized hydrogels, prepared from aqueous blends of poly(methyl vinyl ether-co-maleic acid) (PMVE/MA) and poly(ethylene glycol) (PEG 10,000 Daltons) containing a pore-forming agent (sodium bicarbonate, NaHCO3). Increase in NaHCO3 content increased the equilibrium water content (EWC) and average molecular weight between crosslinks (Mc) of hydrogels. For example, the %EWC was 731, 860, 1109, and 7536% and the Mc was 8.26, 31.64, 30.04, and 3010.00 × 105 g/mol for hydrogels prepared from aqueous blends containing 0, 1, 2, and 5% w/w of NaHCO3, respectively. Increase in NaHCO3 content also resulted in increased permeation of insulin. After 24 h, percentage permeation was 0.94, 3.68, and 25.71% across hydrogel membranes prepared from aqueous blends containing 0, 2, and 5% w/w of NaHCO3, respectively. Hydrogels containing the pore-forming agent were fabricated into microneedles (MNs) for transdermal drug delivery applications by integrating the MNs with insulin-loaded patches. It was observed that the mean amount of insulin permeating across neonatal porcine skin in vitro was 20.62% and 52.48% from hydrogel MNs prepared from aqueous blends containing 0 and 5% w/w of NaHCO3. We believe that these pore-forming hydrogels are likely to prove extremely useful for applications in transdermal drug delivery of biomolecules. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
999.
Myszka K Leja K Olejnik-Schmidt AK Czaczyk K 《Journal of Bioscience and Bioengineering》2012,113(5):631-633
A selective isolation procedure of clostridial strains from natural samples able to convert glycerol to 1,3-propanediol (1,3-PD) and organic acids was investigated. The modified PY medium of high concentration of NaHCO(3) was shown to be highly selective for Clostridium bifermentans. Obtained isolates produced mainly 1,3-PD, lactic, acetic, and formic acids from glycerol. 相似文献
1000.
Flak D Braun A Michalow KA Wyrwa J Parlinska-Wojtan M Graule T Rekas M 《Journal of nanoscience and nanotechnology》2012,12(8):6401-6411
Nanoscaled Fe2O3 powders as candidates for gas sensing material for hydrogen detection were synthesized by the high temperature flame spray assisted combustion of ferrocene dissolved in benzene. X-ray diffraction (XRD) and selected area electron diffraction (SAED) show that the as prepared nanopowder consists of maghemite (gamma-Fe2O3) with low crystallinity. Thermal post-treatment causes a phase transformation towards hematite (alpha-Fe2O3) accompanied by an increase in the crystallinity. Upon exposure to air and hydrogen at elevated temperatures, both phases show a significant variation of conductivity and activation energy-as evidenced by impedance spectra-and thus a favorable sensor response, surpassing even that of flame-synthesized nanocrystalline tin dioxide. The conductivity has been identified as of electronic origin, affected by trap states located in the region adjacent to grain boundaries. Quantitative analysis of the impedance spectra with equivalent circuits shows that the conductivity is thermally activated and affected by the interaction of hydrogen with the sensor material. The calculated Debye screening length of gamma-Fe2O3 and alpha-Fe2O3 is about 27 nm and 16 nm, respectively, what contributes significantly to the sensitivity of the material. Gamma-Fe2O3 and alpha-Fe2O3 exhibit high sensor response towards hydrogen in a wide concentration range. Gamma-Fe2O3 shows n-type semiconducting behavior up to 573 K. Alpha-Fe2O3 shows p-type semiconducting behavior, as reflected in the dynamic changes of the resistivity. For both sensor materials, 523 K was the optimal operating temperature. 相似文献