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581.
Joanna Kurczewska B?a?ej Gierczyk Micha? Ceg?owski Grzegorz Schroeder 《Thin solid films》2009,517(21):6076-6080
Three different magnetic iron oxide-silica matrices with polyoxaalkyl units have been obtained in a multi-step synthesis. The structures of the matrices were confirmed by Fourier transform infrared spectroscopy, while their surface morphology was analyzed by scanning electron microscopy. The scavenging ability was studied by ultraviolet-visible measurements. The results demonstrate very good scavenging efficiency of compounds studied against sodium cations (Na+). The complexing abilities of the magnetic iron oxide-silica surfaces were compared with those of the previously studied analogously modified non-magnetic silica surfaces. 相似文献
582.
The analysis of combustion non-repeatability in the dynamical working conditions of a Diesel engine is presented. In the frame of statistical analysis, applied to a number of acceleration trails, basic determinants such as standard square deviation, skewness, and kurtosis have been calculated for the mean indicated pressure (MIP). The methods of return maps, delay phase portrait reconstruction, recurrence plots and quantification recurrence analysis have been also used to analyze a single chosen course of the measured pressure starting from the idle run of engine, through its acceleration process and ending on a stable engine run with a certain velocity. The results show that recurrence techniques are able to identify various phases of the engine non-stationary work. 相似文献
583.
Lidia Gaffke Krzysztof Kubiak Zuzanna Cyske Grzegorz Wgrzyn 《International journal of molecular sciences》2021,22(16)
The Hfq protein is a bacterial RNA chaperone, involved in many molecular interactions, including control of actions of various small RNA regulatory molecules. We found that the presence of Hfq was required for survival of plasmid-containing Escherichia coli cells against high concentrations of chloramphenicol (plasmid p27cmr), tetracycline (pSC101, pBR322) and ampicillin (pBR322), as hfq+ strains were more resistant to these antibiotics than the hfq-null mutant. In striking contrast, production of Hfq resulted in low resistance to high concentrations of kanamycin when the antibiotic-resistance marker was chromosome-borne, with deletion of hfq resulting in increasing bacterial survival. These results were observed both in solid and liquid medium, suggesting that antibiotic resistance is an intrinsic feature of these strains rather than a consequence of adaptation. Despite its major role as RNA chaperone, which also affects mRNA stability, Hfq was not found to significantly affect kan and tet mRNAs turnover. Nevertheless, kan mRNA steady-state levels were higher in the hfq-null mutant compared to the hfq+ strain, suggesting that Hfq can act as a repressor of kan expression.This observation does correlate with the enhanced resistance to high levels of kanamycin observed in the hfq-null mutant. Furthermore, dependency on Hfq for resistance to high doses of tetracycline was found to depend on plasmid copy number, which was only observed when the resistance marker was expressed from a low copy plasmid (pSC101) but not from a medium copy plasmid (pBR322). This suggests that Hfq may influence survival against high doses of antibiotics through mechanisms that remain to be determined. Studies with pBR322Δrom may also suggest an interplay between Hfq and Rom in the regulation of ColE1-like plasmid replication. Results of experiments with a mutant devoid of the part of the hfq gene coding for the C-terminal region of Hfq suggested that this region, as well as the N-terminal region, may be involved in the regulation of expression of antibiotic resistance in E. coli independently. 相似文献
584.
585.
Transition metal oxides (FeO1.5 and CoO) were added to Gd-doped ceria (Gd0.1Ce0.9O2−δ, GDC) powder for preparing the thin-film electrolyte used in the anode-supported intermediate-temperature solid oxide fuel cell (SOFC). NiO–GDC anode substrate in a weight ratio of 65:35 was fabricated by the tape-casting method. Thin-film electrolyte was fabricated on the pre-sintered anode substrate by screen-printing method and then co-sintered to form the electrolyte/anode bilayer. The cathode, which is made of La0.6Sr0.4Fe0.8Co0.2O3 and GDC (LSCF–GDC) in a weight ratio of 50:50, was screen-printed on the thus-prepared electrolyte surface and sintered to form a complete single cell. The effects of transition metal oxides on the densification of thin-film GDC electrolyte and on the performance of intermediate-temperature SOFC were studied. Results showed that the densification temperature of thin-film GDC electrolyte could not be further reduced by modifying it with transition metal oxides (FeO1.5 and CoO) as sintering aids. Both the addition of Fe and Co to GDC enhanced the p-type conductivity of the electrolyte resulting in decreased ohmic resistance. However, they played different effects on the polarization behavior of the cells. Fe-loading decreased the single cell polarization resistance, thus greatly enhancing the charge-transfer process below 600 °C. At 500 °C, the charge-transfer resistance of the single cell with Fe-loaded GDC electrolyte is only 78% of that of the cell with pure GDC electrolyte. Conversely, Co-loading inhibited the charge-transfer process in the whole testing temperature range. Thus, it can be concluded that Fe-loaded GDC electrolyte is a promising electrolyte material for intermediate- and low-temperature SOFC. 相似文献
586.
UV radiation present in the environment may induce several eye disorders including inflammation and cataract. The aim of this work was to study catalase activity and Mg, Cu, Ca and Zn contents in the eyeballs of gibel carp exposed to ecologically relevant doses of UV radiation (0.09 kJ/m2 for UV-A and 0.98 kJ/m2 for UV-B) simulated in laboratory conditions. Ultraviolet exposure resulted in significant reduction of catalase activity in the eyeballs of tested fish. Reductions in Mg, Cu and Ca contents after UV exposure were also observed. The differences in Mg and Cu levels between control and UV exposed animals were statistically significant, whereas the reduction of Ca level was insignificant. Zinc level in the eyeballs of UV-exposed fish was significantly higher than in non-irradiated specimens. The results suggest that ultraviolet radiation affects prooxidant/antioxidant balance and Mg, Cu, Zn contents in the eyes of fish living in shallow habitats. These may lead to cataract formation. 相似文献
587.
Grzegorz A. Czapski Lidia Babiec Henryk Jko Magdalena Gssowska-Dobrowolska Magdalena Cielik Marta Matuszewska Magorzata Frontczak-Baniewicz Karolina Zajdel Agata Adamczyk 《International journal of molecular sciences》2021,22(18)
Tuberous sclerosis complex (TSC) is a rare, multi-system genetic disease with serious neurological and mental symptoms, including autism. Mutations in the TSC1/TSC2 genes lead to the overactivation of mTOR signalling, which is also linked to nonsyndromic autism. Our aim was to analyse synaptic pathology in a transgenic model of TSC: two-month-old male B6;129S4-Tsc2tm1Djk/J mice with Tsc2 haploinsufficiency. Significant brain-region-dependent alterations in the expression of several synaptic proteins were identified. The most prominent changes were observed in the immunoreactivity of presynaptic VAMP1/2 (ca. 50% increase) and phospho-synapsin-1 (Ser62/67) (ca. 80% increase). Transmission electron microscopy demonstrated serious ultrastructural abnormalities in synapses such as a blurred structure of synaptic density and a significantly increased number of synaptic vesicles. The impairment of synaptic mitochondrial ultrastructure was represented by excessive elongation, swelling, and blurred crista contours. Polyribosomes in the cytoplasm and swollen Golgi apparatus suggest possible impairment of protein metabolism. Moreover, the delamination of myelin and the presence of vacuolar structures in the cell nucleus were observed. We also report that Tsc2+/− mice displayed increased brain weights and sizes. The behavioural analysis demonstrated the impairment of memory function, as established in the novel object recognition test. To summarise, our data indicate serious synaptic impairment in the brains of male Tsc2+/− mice. 相似文献
588.
Sorption properties of bog iron ores with respect to Pb, Cu, Zn, Cr are evaluated at various pH. Maximum sorption determined in the experiments equals to 97.0, 25.2, 25.5, 55.0mg/g for lead(II), copper(II), zinc(II), and chromium(III), respectively. Chromium(VI) is bound in the amount of up to 10.0mg/g. The values of desorption indicate that most of the metals remain stably bound to the surface of bog iron ores, indicating that the chemisorption process prevails. The metals are sorbed as cations at the pH values from 4 to 9. Within this pH range up to 100% of the initial metal amount is immobilized. 90-100% of Cr(VI) is sorbed at pH between 3 and 5. Such properties, combined with favorable conditions of shallow mining and resultant low costs, may be regarded as an incentive for local utilization of bog iron ores in the environmental protection practice. 相似文献
589.
Degrees of Antioxidant Protection: A 2‐Year Study of the Bioactive Properties of Organic Milk in Poland 下载免费PDF全文
Kamila Puppel Tomasz Sakowski Beata Kuczyńska Grzegorz Grodkowski Marcin Gołębiewski Jerzy Barszczewski Barbara Wróbel Arkadiusz Budziński Aleksandra Kapusta Marek Balcerak 《Journal of food science》2017,82(2):523-528
The aim of this study was to determine the nutritional value of organic milk in Poland, investigate the influence of diet on antioxidant capacity and degree of antioxidant protection (DAP), and to examine the effect of season on the bioactive properties of milk from organic farms. From 2014 to 2015, 820 milk samples were collected from 6 organic farms during indoor feeding season (IDS) and pasture feeding season (PS). Pasture feeding season + corn grain (PSCG) cows’ daily ration during pasture feeding season was enriched with 4 kg a day of corn to improve dietary energy balance. Milk obtained during PS was found to have a higher fat content, slight but significantly lower protein content compared with milk from IDS. The study showed that the content of monounsaturated fatty acids (MUFA) in milk fat was strongly linked to the concentration of polyunsaturated fatty acids (PUFA) and, to a lesser extent, on the supply of MUFA. The IDS data (concentration of vitamin E, A, and β‐carotene) showed the lowest values compared with the PS and PSCG groups. Total antioxidant status (TAS) and DAP showed an increasing trend in organic milk. PSCG was associated with highest level of DAP (9% higher than PS and 79% higher than IDS) and TAS (37% higher than PS and 79% higher than IDS). The results obtained show that supplementation of the basic ration with corn grain improved both TAS and DAP. The higher DAP and TAS value is responsible for product stability, considering the risk factor related to levels of cholesterol‐oxide intake in humans. 相似文献
590.