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101.
The perovskite Gd0.9Ba0.1CoO3 was prepared via solution and solution-polymerization methods in aqueous media. The thermal decomposition of precursor powders produced well crystallized nanostructured materials possessing an extensive nanoporosity. The average particle size obtained by the solution route was 150 nm, whereas by the solution-polymerization method was 61 nm. The characterization of gas response, performed on thick-films, revealed that the electrical resistance variation increases with reducing grain size. In oxygen, the films prepared with powder of solution-polymerization registered an increment of 1000%, compared to the powder made by the solution route, whereas in carbon dioxide was 1100%. 相似文献
102.
103.
Shenheng Guan Alma L. Burlingame 《Journal of the American Society for Mass Spectrometry》2010,21(3):455-459
Stored waveform inverse Fourier transform (SWIFT) technology has been implemented on a commercial Fourier transform ICR mass
spectrometer. Complex ejection/isolation waveforms can be generated on an arbitrary waveform generator (AWG) and applied to
the instrument by use of a high speed analog switch. High mass selectivity and subsequent electron capture dissociation (ECD)
of the SWIFT isolated ions has been demonstrated with analysis of intact Bovine histone H4. A mass selectivity about 0.1 m/z unit for isolation of the 18+ charge state ions was achieved. Adaptation of SWIFT on the commercial instrument provides an
enhanced capability for characterizing intact proteins by top-down analysis. 相似文献
104.
105.
Mueller JW Link NM Matena A Hoppstock L Rüppel A Bayer P Blankenfeldt W 《Journal of the American Chemical Society》2011,133(50):20096-20099
Parvulins compose a family of small peptidyl-prolyl isomerases (PPIases) involved in protein folding and protein quality control. A number of amino acids in the catalytic cavity are highly conserved, but their precise role within the catalytic mechanism is unknown. The 0.8 ? crystal structure of the prolyl isomerase domain of parvulin Par14 shows the electron density of hydrogen atoms between the D74, H42, H123, and T118 side chains. This threonine residue has previously not been associated with catalysis, but a corresponding T152A mutant of Pin1 shows a dramatic reduction of catalytic activity without compromising protein stability. The observed catalytic tetrad is strikingly conserved in Pin1- and parvulin-type proteins and hence constitutes a common feature of small peptidyl prolyl isomerases. 相似文献
106.
New agricultural strategies aim to reduce the use of pesticides due to their damage to the environment and humans, and the caused resistance to pathogens. Therefore, alternative sources of antifungal compounds from plants are under investigation lately. Extracts from plants have a wide composition of chemical compounds which may complicate the development of pathogen resistance. Botrytis cinerea, causing grey mould, is an important horticultural and ornamental pathogen, responsible for the relevant yield and quality losses. B. cinerea isolated from a different plant host may differ in the sensitivity to antifungal substances from plants. Assessing the importance of research covering a wide range of pathogens for the rapid development of biopesticides, this study aims to determine the sensitivity of the B. cinerea isolate complex (10 strains) to plant extracts, describe morphological changes caused by the extract treatment, and detect differences between the sensitivity of different plant host isolates. The results showed the highest sensitivity of the B. cinerea isolates complex to cinnamon extract, and the lowest to laurel extract. In contrast, laurel extract caused the most changes of morphological attributes in the isolates. Five B. cinerea isolates from plant hosts of raspberry, cabbage, apple, bell pepper, and rose were grouped statistically according to their sensitivity to laurel extract. Meanwhile, the bell pepper isolate separated from the isolate complex based on its sensitivity to clove extract, and the strawberry and apple isolates based on their sensitivity to cinnamon extract. 相似文献
107.
Alma Rosa Corrales Escobosa Julio Alberto Landero Figueroa J. Félix Gutiérrez Corona Katarzyna Wrobel Kazimierz Wrobel 《Analytical and bioanalytical chemistry》2009,394(8):2267-2276
The intent of this work was to gain further insight on the fungus-assisted degradation/solubilization of humic acid and the
related changes in metal-binding profiles. In the experimental design, Aldrich reagent humic acid (HA) or HA enriched with
Cu, Pb, and Ni (HA(Me)) was added to Fusarium oxysporum f. sp. lycopersici cultures in vitro. The cultures were supplied by different carbon- and nitrogen-containing nutrients (glucose, Glc, or glutamate,
Glu and ammonium, NH4+, or nitrate, NO3−, ions, respectively) in order to examine their possible effect on HA and HA(Me) decomposition. During the first 48 h of fungus
growth, gradual acidification to pH 2 was observed in medium containing Glc + NH4+, while for other cultures, alkalinization to pH 9 occurred and then, the above conditions were stable up to at least 200 h.
Size exclusion chromatography (SEC) with UV/Vis detection showed progressive degradation and solubilization of both HA and
HA(Me) with the increasing time of fungus growth. However, the molecular mass distributions of HA-related soluble species
were different in the presence of metals (HA(Me)) as referred to HA and were also influenced by the composition of growth
medium. The solubilization of Pb, Cu, and Ni and their association with HA molecular mass fractions were studied using inductively
coupled plasma mass spectrometry (ICP-MS) detection. Under acidic conditions, relatively high concentrations of low-molecular-mass
metallic species were found in culture supernatants, while in alkaline media, metal solubilization was generally poorer. In
contrast to low pH culture, SEC-ICP-MS results obtained in alkaline supernatants indicated metal binding to degradation products
of humic substances of MM > 5 kDa. In summary, the results of this study suggest that fungus-assisted degradation of HA and
HA(Me) might be controlled using appropriate N- and C- sources required for fungus growth, which in turn would affect molecular
mass distribution of soluble metallic species thus potentially influencing their actual bioaccessibility.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
108.
An expeditious transformation of 5-acyl-2H-pyran-2-ones with various amidines as 1,3-binucleophiles into isomerically pure (E)-α,β-didehydro-α-amino acid derivatives (DDAAD) containing the 5-pyrimidyl moiety at the β-position is described. The method was performed in ethanolic (or ethanol/water) solutions in the presence of Na2CO3 as a nontoxic base and under microwave-assisted conditions. When starting from the 5-ethoxycarbonyl-2H-pyran-2-one derivative and in the presence of DBU as a base the corresponding pyrano[2,3-d]pyrimidines were prepared. 相似文献
109.
Roberto Fernández de la Pradilla Prof. Dr. Carlos Montero Dr. Mariola Tortosa Dr. Alma Viso Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(3):697-709
Highly diastereoselective Claisen rearrangements of acyclic allyl vinyl ethers bearing a chiral sulfoxide at C‐5 provide γ‐δ‐unsaturated aldehydes or ketones with up to two consecutive asymmetric centers in the molecule whilst preserving a useful vinyl sulfoxide. The reactivity of related vinyl sulfides and sulfones has also been examined in this work. 相似文献
110.
Figueroa FL Escassi L Pérez-Rodríguez E Korbee N Giles AD Johnsen G 《Journal of photochemistry and photobiology. B, Biology》2003,69(1):21-30
The effect of irradiance (40 and 840 micromol photons m(-2) s(-1)) of short-term (48 h) irradiation on photosynthetic activity (estimated as oxygen evolution and as chlorophyll fluorescence), specific absorption and fluorescence excitation spectra, photosynthetic pigment accumulation (chlorophyll a and biliproteins) and UV-absorbing compounds (mycosporine-like amino acids, MAAs) was investigated in sun and shade species of the red algal genus Porphyra collected in Trondheimsfjord (Norway). In the sun type, high irradiance exposure (840 micromol photons m(-2) s(-1)) did not alter the Chl a concentration, however, exposure to a lower irradiance (40 micromol photons m(-2) s(-1)) for 48 h significantly increased the chlorophyll concentration. The content of MAAs was significantly higher in the suntype than in the shade type algae. Porphyra-334 is the main MAA in this species followed by shinorine. The total content of MAAs significantly (P<0.05) increased in the sun type after 48 h exposure to both high and low irradiances. However, in the shade type, porphyra-334 significantly decreased (P<0.05) after both high and low irradiance exposure. Photosynthetic activity (as oxygen evolution) and the optimal quantum yield (F(v)/F(m)), as an indicator of photoinhibition, decreased under low and high irradiance in the shade type algae and no full recovery was observed when the algae were transferred to very low irradiation.The sun type algae presented a higher capacity of acclimation to increased irradiance than the shade type algae. This high acclimation of sun type algae to short term high irradiance exposure (48 h) is explained by the higher thermal dissipation. This was estimated as the ratio of nonphotochemical quenching related to the light dose (q(N):dose) and by the accumulation of MAAs. 相似文献