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Alexander B. Tuzikov Alexandra S. Gambaryan Lekh Raj Juneja Nicolai V. Bovin 《Journal of carbohydrate chemistry》2013,32(9):1191-1200
ABSTRACT To investigate the specificity of various influenza virus strains we have prepared polyacrylic type conjugates of undecasaccharide (Neu5Acα2-6Galβ1-4GlcNAcβ1-2Manα1)2-3,6Manβ1-4GlcNAcβ1-4GlcNAc (YDS), and trisaccharides 6‵-sialyl-N-acetyllactosamine (6‵SLN), 6‵-sialyllactose (6‵SL), and 3‵-sialyllactose (3‵SL). Free oligosaccharides were transformed to glycosylamine-1-N-glycyl derivatives by sequential action of NH4HCO3, chloroacetic anhydride, and aqueous NH3. The known derivatization protocol has been optimized for these sialooligosaccharides. Coupling of obtained amino-spacered derivatives with poly(4-nitrophenyl acrylate) gave rise to two types of conjugates, namely with polyacrylic acid and polyacrylamide backbones; the conversion proceeded quantitatively and without destruction of the oligosaccharides. The content of oligosaccharides in the conjugates was 10, 20, and 30% mol for 3‵SL, 6‵SL, 6‵SLN, and 2, 5 and 10% mol for YDS. Free oligosaccharides and the glycoconjugates were tested as inhibitors of influenza virus adhesion, and also as blockers of virus infectivity in MDCK cell culture. Biantennary YDS demonstrated similar activity to trisaccharide 6‵SLN both as the free form and neoglycoconjugate. 相似文献
415.
Systematic investigations on the influence of electron beam radiation of different dosage on molecular degradation as well as crosslinking of ultra-high molar mass polyethylene containing various amounts of α-tocopherol as stabilizer were carried out in air and an inert nitrogen atmosphere. The samples were analyzed with respect to their content of insoluble crosslinked fraction and the molar mass distribution of the soluble fraction. The extent of crosslinking and degradation is dependend on the absorbed dosage of the radiation. The crosslinking process is favored in nitrogen atmosphere whereas in air molecular degradation is increasing. The extent of crosslinking as well as degradation can be reduced by the addition of α-tocopherol both, in air and nitrogen. 相似文献
416.
X‐ray photoelectron and x‐ray excited Auger spectra were measured for the intermetallic compounds LiMGa2 and Li2MGa (M = Rh, Pd, Ir, Pt). The valence band spectra exhibit characteristic differences in the location of the M d‐band between group 9 elements (Rh, Ir) and group 10 elements (Pd, Pt) on one side and between LiMGa2 and Li2MGa on the other. The experimentally observed differences are in excellent agreement with results from band structure calculations. The combination of binding energy shifts with Auger kinetic energy shifts allowed a separation of initial and final state contributions. Core hole screening is very efficient in accordance with the metallic character of the investigated phases. The magnitude of the screening correlates with the theoretically predicted composition of the density of states at the Fermi level. Application of Wertheim's electrostatic model allowed to estimate the charge distribution for LiRhGa2 and Li2RhGa. The sign of the charges agrees with expectations that result from the Extended Zintl Concept. The results show, how dangerous it is to draw conclusions on the chemistry of such systems from photoemission data alone. 相似文献
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Julietta Moustaka Nicolai Vitt Meyling Thure Pavlo Hauser 《Molecules (Basel, Switzerland)》2022,27(1)
The escalating food demand and loss to herbivores has led to increasing interest in using resistance-inducing microbes for pest control. Here, we evaluated whether root-inoculation with fungi that are otherwise known as entomopathogens improves tomato (Solanum lycopersicum) leaflets’ reaction to herbivory by Spodoptera exigua (beet armyworm) larvae using chlorophyll fluorescence imaging. Plants were inoculated with Metarhizium brunneum or Beauveria bassiana, and photosystem II reactions were evaluated before and after larval feeding. Before herbivory, the fraction of absorbed light energy used for photochemistry (ΦPSII) was lower in M. brunneum-inoculated than in control plants, but not in B. bassiana-inoculated plants. After herbivory, however, ΦPSII increased in the fungal-inoculated plants compared with that before herbivory, similar to the reaction of control plants. At the same time, the fraction of energy dissipated as heat (ΦNPQ) decreased in the inoculated plants, resulting in an increased fraction of nonregulated energy loss (ΦNO) in M. brunneum. This indicates an increased singlet oxygen (1O2) formation not detected in B. bassiana-inoculated plants, showing that the two entomopathogenic fungi differentially modulate the leaflets’ response to herbivory. Overall, our results show that M. brunneum inoculation had a negative effect on the photosynthetic efficiency before herbivory, while B. bassiana inoculation had no significant effect. However, S. exigua leaf biting activated the same compensatory PSII response mechanism in tomato plants of both fungal-inoculated treatments as in control plants. 相似文献
419.
Nicolai Plat Arkady Litmanovich Victor Yashin Yaroslav Kudryavtsev Elena Govorun 《Macromolecular Symposia》1997,118(1):347-362
The main task of the theory of macromolecular reactions in polymer blends is to describe an evolution of the blend structure under the concerted action of the reaction and interdiffusion. For a polymeranalogous reaction proceeding with autoacceleration in a compatible blend, the task has been solved by methods of linear non-equilibrium thermodynamics. The set of reaction-diffusion equations derived permits to describe the blend structure in details, including the parameters characterizing compositional heterogeneity and units' distribution of the reacting chains in any local region of the blend. For incompatible blend of two homopolymers, the competition between a phase separation and the reaction of end-coupling with a formation of diblock-copolymer has been considered. The peculiarities of the processes mentioned as well as the actual problems in this field are discussed. 相似文献
420.
V. Lesturgeon D. Durand T. Nicolai 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(1):83-91
Free radical co-polymerization of methyl methacrylate (MMA) and ethyl glycol dimethyl methacrylate (EGDMA) in solution leads
to the formation of polydisperse branched PMMA which grows in size until the system gels. The structure and the size distribution
of the PMMA aggregates were characterized at infinite dilution using static and dynamic light scattering and size exclusion
chromatography (SEC). The reaction extent was measured using SEC and Raman spectroscopy. The results show that the structure
and size distribution of PMMA aggregates formed close to the gel point are compatible with those of percolating clusters.
The structure factor of semi-dilute solutions of PMMA aggregates is the same as that of dilute solutions at distance scales
much smaller than the correlation length of the concentration fluctuations (). However, the cut-off function of the pair correlation function at for semi-dilute solutions is more gradual than the cut-off function at for dilute solutions.
Received 11 May 1998 and Received in final form 22 October 1998 相似文献