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排序方式: 共有810条查询结果,搜索用时 15 毫秒
91.
Zdeňka Sedláková Josef Pleštil Josef Baldrian Miroslav Šlouf Pavel Holub 《Polymer Bulletin》2009,63(3):365-384
A series of novel polystyrene and poly(butyl methacrylate) montmorillonites (MMT-Na) nanocomposite latexes have been successfully
prepared by emulsion polymerization. First of all, chemical modification of MMT-Na with a reactive coupling agent (MMT-QS)
has been employed for the synthesis of hybrids. Subsequently, in situ seeded emulsion polymerization of hydrophobic vinyl
monomers, such as butyl methacrylate and styrene, using sodium dodecyl sulfate (SDS) and ammonium persulfate (APS) as surfactant
and initiator, respectively, were used for nanocomposite preparation. This technique allowed preparing of stable nanocomposite
latexes with high (30–45 wt.%) solids contents and with loading of inorganic particles up to 5 wt.%. The prepared wet dispersions
were subsequently characterized by light scattering method. In order to characterize the microstructure of the clay layers,
and that of the organoclay in polystyrene and poly(butyl methacrylate) nanocomposites, wide and small angle X-ray analyses
(WAXS, SAXS) and transmission electron microscopy (TEM) techniques were used. 相似文献
92.
93.
Vera P. Pavlović Jelena D. Vujančević Pavle Mašković Jovana Ćirković Jelena M. Papan Darko Kosanović Miroslav D. Dramićanin Predrag B. Petrović Branislav Vlahović Vladimir B. Pavlović 《Journal of the American Ceramic Society》2019,102(12):7735-7745
Titanium dioxide is a photocatalyst, known not only for its ability to oxidize organic contaminants, but also for its antimicrobial properties. In this article, significant enhancement of the antimicrobial activity of TiO2 (up to 32 times) was demonstrated after its activation by ball milling. The antimicrobial activity was analyzed for one fungal and 13 bacterial ATCC strains using the microdilution method and recording the minimum inhibitory concentration (MIC) values. In order to further investigate the correlation between the mechanical activation of TiO2 and its antimicrobial activity, the structure, morphology and phase composition of the material were studied by means of Electron Microscopy, X-ray diffraction and nitrogen adsorption-desorption measurements. UV-Vis diffuse reflectance spectra were recorded and the Kubelka-Munk function was applied to convert reflectance into the equivalent band gap energy (Eg) and, consequently, to investigate changes in the Eg value. X-ray photoelectron spectroscopy was used to analyze the influence of mechanical activation on the Ti 2p and O 1s spectra. The presented results are expected to enable the development of more sustainable and effective advanced TiO2-based materials with antimicrobial properties that could be used in numerous green technology applications. 相似文献
94.
Nadezhda Todorova Miroslav Rangelov Vanya Bogoeva Vishnya Stoyanova Anna Yordanova Ginka Nikolova Hristo Georgiev Daniela Dimitrova Safa Mohedin Katerina Stoyanova Ivanka Tsacheva 《International journal of molecular sciences》2021,22(15)
We addressed the issue of C1q autoantigenicity by studying the structural features of the autoepitopes recognized by the polyclonal anti-C1q antibodies present in Lupus Nephritis (LN) sera. We used six fractions of anti-C1q as antigens and selected anti-idiotypic scFv antibodies from the phage library “Griffin.1”. The monoclonal scFv A1 was the most potent inhibitor of the recognition of C1q and its fragments ghA, ghB and ghC, comprising the globular domain gC1q, by the lupus autoantibodies. It was sequenced and in silico folded by molecular dynamics into a 3D structure. The generated 3D model of A1 elucidated CDR similarity to the apical region of gC1q, thus mapping indirectly for the first time a globular autoepitope of C1q. The VH CDR2 of A1 mimicked the ghA sequence GSEAD suggested as a cross-epitope between anti-DNA and anti-C1q antibodies. Other potential inhibitors of the recognition of C1q by the LN autoantibodies among the selected recombinant antibodies were the monoclonal scFv F6, F9 and A12. 相似文献
95.
Plastic immersed heat exchangers are used in various applications where chemically neutral and noncorrosive equipment is required. Their potential competitors, namely, polymeric hollow‐fiber bundles, were investigated. Three different fiber bundles were tested as immersed coolers of a hot reservoir. Two types of polypropylene hollow fibers with various outside diameters were employed. Fibers were twisted with different curvature to achieve better distribution and improve natural convection on their outer surface. Calculation by experimental results was compared with the equation for natural convection across the horizontal cylinder, which overestimates heat transfer coefficients and can be applied for only rough estimation. Experimentally achieved pressure drops agreed well with theoretical prediction for laminar flow. 相似文献
96.
Slobodan D. Dolić Dragana J. Jovanović Krisjanis Smits Biljana Babić Milena Marinović-Cincović Slavica Porobić Miroslav D. Dramićanin 《Ceramics International》2018,44(15):17953-17961
Monoclinic scheelite-type BiVO4 is currently considered as one of the most promising non-titania photocatalysts, wheras tetragonal zircon-type BiVO4 is still poorly understood. Herein, a new and simple synthetic approach was applied and nanostructured single-phase zircon-type BiVO4 was successfully prepared by a controllable ethylene-glycol colloidal route. In addition, nanostructured monoclinic scheelite-type BiVO4 powders were also fabricated through annealing of the as-prepared samples. A comparative study of the two BiVO4 polymorphs was conducted and it turned out that the novel synthetic approach had a significant impact on porosity and photocatalytic performance of zircon-structured BiVO4. All the prepared materials, as-prepared and annealed, were mesoporous, while measured values of specific surface area of some zircon-structured samples (~34?m2/g) were ~7 times higher than those reported thus far for this phase. Interestingly, for the first time, zircon-type BiVO4, previously considered to be a poor photocatalyst, exhibited a better overall performance in degradation of methyl orange compared to monoclinic scheelite-type BiVO4. Hence, it could be expected that the here-presented synthesis and observations will both arouse interest in scarcely studied tetragonal zircon-type BiVO4 and facilitate as well as speed up further research of its properties. 相似文献
97.
Ordinary Gasoline Emissions Induce a Toxic Response in Bronchial Cells Grown at Air-Liquid Interface
Tereza Cervena Michal Vojtisek-Lom Kristyna Vrbova Antonin Ambroz Zuzana Novakova Fatima Elzeinova Michal Sima Vit Beranek Martin Pechout David Macoun Jiri Klema Andrea Rossnerova Miroslav Ciganek Jan Topinka Pavel Rossner Jr. 《International journal of molecular sciences》2021,22(1)
Gasoline engine emissions have been classified as possibly carcinogenic to humans and represent a significant health risk. In this study, we used MucilAir™, a three-dimensional (3D) model of the human airway, and BEAS-2B, cells originating from the human bronchial epithelium, grown at the air-liquid interface to assess the toxicity of ordinary gasoline exhaust produced by a direct injection spark ignition engine. The transepithelial electrical resistance (TEER), production of mucin, and lactate dehydrogenase (LDH) and adenylate kinase (AK) activities were analyzed after one day and five days of exposure. The induction of double-stranded DNA breaks was measured by the detection of histone H2AX phosphorylation. Next-generation sequencing was used to analyze the modulation of expression of the relevant 370 genes. The exposure to gasoline emissions affected the integrity, as well as LDH and AK leakage in the 3D model, particularly after longer exposure periods. Mucin production was mostly decreased with the exception of longer BEAS-2B treatment, for which a significant increase was detected. DNA damage was detected after five days of exposure in the 3D model, but not in BEAS-2B cells. The expression of CYP1A1 and GSTA3 was modulated in MucilAir™ tissues after 5 days of treatment. In BEAS-2B cells, the expression of 39 mRNAs was affected after short exposure, most of them were upregulated. The five days of exposure modulated the expression of 11 genes in this cell line. In conclusion, the ordinary gasoline emissions induced a toxic response in MucilAir™. In BEAS-2B cells, the biological response was less pronounced, mostly limited to gene expression changes. 相似文献
98.
Miroslav Trnka Petr Hlavinka Mikhail A. Semenov 《Journal of the Royal Society Interface》2015,12(112)
Ways of increasing the production of wheat, the most widely grown cereal crop, will need to be found to meet the increasing demand caused by human population growth in the coming decades. This increase must occur despite the decrease in yield gains now being reported in some regions, increased price volatility and the expected increase in the frequency of adverse weather events that can reduce yields. However, if and how the frequency of adverse weather events will change over Europe, the most important wheat-growing area, has not yet been analysed. Here, we show that the accumulated probability of 11 adverse weather events with the potential to significantly reduce yield will increase markedly across all of Europe. We found that by the end of the century, the exposure of the key European wheat-growing areas, where most wheat production is currently concentrated, may increase more than twofold. However, if we consider the entire arable land area of Europe, a greater than threefold increase in risk was predicted. Therefore, shifting wheat production to new producing regions to reduce the risk might not be possible as the risk of adverse events beyond the key wheat-growing areas increases even more. Furthermore, we found a marked increase in wheat exposure to high temperatures, severe droughts and field inaccessibility compared with other types of adverse events. Our results also showed the limitations of some of the presently debated adaptation options and demonstrated the need for development of region-specific strategies. Other regions of the world could be affected by adverse weather events in the future in a way different from that considered here for Europe. This observation emphasizes the importance of conducting similar analyses for other major wheat regions. 相似文献
99.
100.
ABSTRACTRecently, the problem of designing boundary controllers and observers for unstable linear constant-coefficient reaction–diffusion equation on N-balls has been solved by means of the backstepping method. However, the extension of these results to spatially varying coefficients is far from trivial. This work deals with radially varying reaction coefficients under revolution symmetry conditions on a sphere (the three-dimensional case). Under these conditions, the equations become singular in the radius. When applying the backstepping method, a similar type of singularity appears in the backstepping control and observer kernel equations. However, with a simple scaling transformation, we are able to reduce the singular equation to a regular equation, which turns out to be the same kernel equations appearing when using the one-dimensional backstepping method. In addition, the scaling transformation allows us to prove stability in the H 1 space. 相似文献