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501.
Loura LM Coutinho A Silva A Fedorov A Prieto M 《The journal of physical chemistry. B》2006,110(15):8130-8141
We studied the effect of a model basic peptide, hexalysiltryptophan, on the organization of dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylserine unilamellar vesicles by means of fluorescent resonance energy transfer (FRET) between fluorescently labeled phospholipids. Several FRET theoretical models assuming different bilayer geometries and probe distributions were fitted to the time-resolved data. The experiments were carried out at two temperatures in different regions of the lipid mixture phase diagram. At 45 degrees C, the expected gel/fluid phase separation was verified by model fitting in peptide-free vesicles, which from the FRET approach means that domains are larger than approximately 200 A. No noticeable alteration of membrane organization was detected upon increasing the peptide concentration. At variance, for the single fluid phase at 60 degrees C, there was a large increase in FRET efficiency upon peptide addition to the lipid vesicles, mainly caused by peptide-induced vesicle aggregation. The system gradually changed from unilamellar lipid vesicles to a multibilayer geometry, and a limit lamellar repeat distance of approximately 57 A was recovered. Furthermore, no evidence for lateral domain formation on the FRET length scale was found at this temperature, the cationic peptide being only able to induce local lipid demixing, causing a short-range sequestration of 2-3 acidic lipids around each surface-adsorbed peptide. 相似文献
502.
The aim was to evaluate the interaction between selected alcoholamines and components of artificial skin sebum. The rate and depth of penetration into the lipophilic bead imitating pilosebaceous unit lumen was applied for alcoholamine penetration activity assay. The activity differentiation of 0.5% aqueous alcoholamine solutions with a potential cleansing effect on the pilosebaceous unit was performed. The depth of aminomethylpropanol penetration increased from 0.080 mm after 15 min to 3.049 mm after 72 h. The depth of aminomethylpropendiol penetration increased with time from 0.148 to 4.064, respectively, of diisopropanolamine from 0.481 to 4.626, triethanolamine from 0.236 to 4.342, triisopropanolamine from 0.275 to 2.392 and trometamol from 0.338 to 4.580. The products of alcoholamines reaction with the model skin sebum are easily dispersed in water. The rate of alcoholamines reaction with the model skin sebum depends on the alcoholamine, being the highest in the case of diisopropanolamine, decreasing to minimum for triisopropanolamine. Selected alcoholamines would be applied in ex vivo and in vivo research. 相似文献
503.
Aleksander Ivanov 《Archive for Mathematical Logic》2012,51(1-2):93-98
It is shown that for every Turing degree d there is an ω-categorical group G such that the isomorphism type of G is of degree d. We also find an ω-categorical group G such that the isomorphism type of G has no degree. 相似文献
504.
505.
Mikhail V. Kalyaev Dmitry S. Ryabukhin Marina A. Borisova Alexander Yu. Ivanov Irina A. Boyarskaya Kristina E. Borovkova Lia R. Nikiforova Julia V. Salmova Nikolay V. Ulyanovskii Dmitry S. Kosyakov Aleksander V. Vasilyev 《Molecules (Basel, Switzerland)》2022,27(14)
Reactions of 3-(furan-2-yl)propenoic acids and their esters with arenes in Brønsted superacid TfOH affords products of hydroarylation of the carbon–carbon double bond, 3-aryl-3-(furan-2-yl)propenoic acid derivatives. According to NMR and DFT studies, the corresponding O,C-diprotonated forms of the starting furan acids and esters should be reactive electrophilic species in these transformations. Starting compounds and their hydroarylation products, at a concentration of 64 µg/mL, demonstrate good antimicrobial activity against yeast-like fungi Candida albicans. Apart from that, these compounds suppress Escherichia coli and Staphylococcus aureus. 相似文献
506.
Martin K. Leonowicz Marta Lawecka A. Ślawska-Waniewska Gulzhian I. Dzhardimalieva Aleksander S. Rozenberg Anatolii D. Pomogailo 《Macromolecular Symposia》2003,204(1):257-266
Metallopolymer nanocomposites on the bases of cobalt and iron acrylates as well as their cocrystallites have been obtained and characterized. Microstructure of the materials consists of both agglomerated and individual nanocrystallites which are homogeneously distributed in the polymer matrix. Mean crystallite size is 7-14 nm. All the composite materials exhibit soft magnetic properties at room temperature. The magnetic parameters are controlled by the intrinsic magnetic properties of the constituents and agglomeration of the particles. 相似文献
507.
Polymeric insulation used in high voltage applications and subjected to divergent electric fields emits ultraviolet radiation due to electroluminescence. The chromophores present in the polymer initiate photo-degradation of the material and, in dry environment, this leads to electrical treeing which causes premature failure of the insulation. The role of photostabilizers which can limit the photodegradation caused by ultraviolet radiation is studied for LDPE containing the usual and decreased concentration of air. Degassing or impregnating the polymer with an inert gas decreases the concentration of oxygen and prolongs the time to tree inception because the probability of forming excited or anionic oxygen is reduced. 相似文献
508.
Andrew A. Tolmachev Alexander A. Yurchenko Ernest S. Kozlov Anatoliy S. Merkulov Marina G. Semenova Aleksander M. Pinchuk 《Heteroatom Chemistry》1995,6(5):419-432
The reaction of phosphorus(III) halides with imidazo[1,2-a]pyridines in the presence of bases leads to the formation of 3-phosphorylated imidazo[1,2-a]pyridines. The reaction proceeds in high yield and requires no catalysts. In the compounds obtained, in contrast to phosphorylated indolizines, the phosphorus–heterocycle bond is stable and not cleaved by dry hydrogen chloride, alcohols, or water. Imidazo[1,2-a]pyridines with the phosphinic and phosphinous groups can be alkylated both at the phosphorus and at the nitrogen atom of the heterocycle, the alkylation direction being dependent on the strength of the alkylation reagent used. © 1995 John Wiley & Sons, Inc. 相似文献