The paper presents a study of the effect of a constant magnetic field (CMF) on the basic processes of quercetin electrochemical reactions. According to the observation made in previous studies, the presence of a double bond in the C-ring of quercetin enhances the antioxidant properties of that compound, whereas the presence of −OH groups also affects the antioxidant properties. Using cyclic voltammetry it was found that the constant magnetic field improves the efficiency of quercetin electrooxidation, especially of the third stage of the process, i. e. the stage in which the oxidation of the OH groups in the A-ring is the most difficult. The use of HPLC confirmed the electrochemical measurements and the results of cyclic voltammetry studies. The beneficial effect of the magnetic field on the efficiency of quercetin oxidation was confirmed by the results of impedance spectroscopy measurements. 相似文献
Stapled peptides are chemical entities in‐between biologics and small molecules, which have proven to be the solution to high affinity protein–protein interaction antagonism, while keeping control over pharmacological performance such as stability and membrane penetration. We demonstrate that the multicomponent reaction‐based stapling is an effective strategy for the development of α‐helical peptides with highly potent dual antagonistic action of MDM2 and MDMX binding p53. Such a potent inhibitory activity of p53‐MDM2/X interactions was assessed by fluorescence polarization, microscale thermophoresis, and 2D NMR, while several cocrystal structures with MDM2 were obtained. This MCR stapling protocol proved efficient and versatile in terms of diversity generation at the staple, as evidenced by the incorporation of both exo‐ and endo‐cyclic hydrophobic moieties at the side chain cross‐linkers. The interaction of the Ugi‐staple fragments with the target protein was demonstrated by crystallography. 相似文献
Nanosized carbon black (CB) was introduced into polypropylene/maleic anhydride-grafted polyolefin elastomer/intumescent flame retardant (PP/POE-MA/IFR) system to investigate the effect of nanofiller as synergist on thermal, electrical and mechanical properties of polymer composites. With 5 mass% CB into PP/POE-MA/IFR system (POFC5), the Tmax (corresponded to the temperature at the maximum mass loss rate) under air was increased by 122.4 °C; its limited oxygen index was as high as 31.4%; its vertical burning rating (UL-94) reached V0, and the peak value of heat release rate was decreased to only 19% of neat PP in cone calorimeter testing. Moreover, PP composites exhibited good electrical conductivity with more than 1.6 mass% CB, which is a low loading level to reach the critical percolation concentration. In addition, a good balance on stiffness and toughness of PP composites was achieved; especially, Young’s moduli and impact strength of POFC5 were increased to 1.26 and 2.5 times in comparison with that of neat PP, respectively. These results indicated that CB was an effective synergist in multi-component PP composites to simultaneously improve thermal, electrical and mechanical properties.
Derivatives of pyrimidine‐2(1H)‐selenone are a group of compounds with very strong antimicrobial activity. In order to study the effect of the position of the methoxy substituent on biological activity, molecular geometry and intermolecular interactions in the crystal, three derivatives were prepared and evaluated with respect to their antimicrobial activities, and their crystal structures were determined by X‐ray diffraction. The investigated compounds, namely, 1‐(X‐methoxyphenyl)‐4‐methyl‐6‐phenylpyrimidine‐2(1H)‐selenones (X = 2, 3 and 4 for 1 , 2 and 3 , respectively), C18H16N2OSe, showed very strong activity against selected strains of Gram‐positive bacteria and fungi. Two compounds, 1 and 2 , crystallize in the monoclinic space group P21/c, while 3 crystallizes in the space group P21/n; 1 has two molecules in the asymmetric unit and the other two ( 2 and 3 ) have one molecule. The geometries of the investigated compounds differ slightly in the mutual orientations of the aromatic and pyrimidineselenone rings. The O atom in 1 stabilizes the conformation of the molecules via intramolecular C—H…O hydrogen bonding. The packing of molecules is determined by weak C—H…N and C—H…Se intermolecular interactions and additionally in 1 and 2 by C—H…O intermolecular interactions. The introduction of the methoxy substituent results in greater selectivity of the investigated compounds. 相似文献
Journal of Thermal Analysis and Calorimetry - Tetragonal zirconia (3YSZ) and cermet nickel–tetragonal zirconia (Ni/3YSZ) were obtained by citric method. The porosity of samples was increased... 相似文献
Novel fluorescing dyes 1,3,4-triphenyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl)-1H-pyrazolo[3,4-b]quinoline (K1) and 2-[(2-hydroxyethyl)-(1,3,4-triphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amino]ethanol (L1) have been synthesized and investigated by the means of steady state and time-resolved fluorescence techniques. These compounds
act as sensors for the fluorescence detection of small inorganic cations (lithium, sodium, barium, magnesium and calcium)
in solvents of different polarities (THF and acetonitrile). The mechanism, which allows application of these compounds as
sensors, is an electron transfer from the electro-donative part of molecule to the acceptor part (fluorophore), which is retarded
upon complexation of the electro-donative part by inorganic cations. We found that crown ether-containing compound is very
sensitive to the addition of any investigated ions but amino alcohol-containing one exhibits better selectivity to the addition
of two-valued cations. Two kinds of the complexes (LM+ and L2M+) were found in the investigated systems. In addition, the dyes may be used as fluorescence indicators in solvents of lower
polarity like tetrahydrofuran. 相似文献
(S)-trans-4-Phenylbut-3-en-2-ol has been obtained in excellent yields and with high enantiomeric excess in the reduction of trans-4-phenylbut-3-en-2-one using the comminuted roots of carrot (Daucus carota L.), celeriac (Apium graveolens L. var. rapaceum), and beetroot (Beta vulgaris L. subsp. Vulgaris) in isooctane. This is the first Letter of this bioreduction with plant tissue in an organic solvent. 相似文献
Cocrystallization of baicalein with nicotinamide yields a 1:1 cocrystal [systematic name: pyridine‐3‐carboxamide–5,6,7‐trihydroxy‐2‐phenyl‐4H‐chromen‐4‐one (1/1)], C6H6N2O·C15H10O5. The asymmetric unit contains one baicalein and one nicotinamide molecule, both in neutral forms. Molecules in the cocrystal form column motifs stabilized by an array of intermolecular hydrogen bonds. 相似文献
In our work we propose a novel method of analysis of photorefractive transport equations. The method based on a perturbative
approach can be used in the case of two wave mixing and four wave mixing geometry, i.e. for the samples illuminated by interference
patterns. Presented approach can be employed for a broad range of material and experimental parameters, particularly for arbitrary
depth of light modulation pattern. The approximate analytical solution is compared with results of numerical calculations
and a good agreement practically in every case was found.
Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Šwinoujście, Poland 相似文献