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31.
Viktória Torma Tamás Gyenes Zoltán Szakács Béla Noszál Árpád Némethy Miklós Zrínyi 《Polymer Bulletin》2007,59(3):311-318
Summary Entirely amino acid-based polymers were prepared by side-chain attachment to polysuccinimide derived from the thermal polycondensation
of aspartic acid. Following deprotonation of various amino acid ester hydrochlorides by a secondary amine, the restored primary
amino groups initiated the ring-opening of succinimide to form amide bonds. 1H and 13C NMR measurements revealed that the mole fraction of the introduced amino acid side chains could be controlled by the reaction
time, while no hydrolysis of methyl ester groups was observed. The synthesized polymers contain exclusively amino acids, which
makes them promising candidates as base materials of controlled drug delivery systems. 相似文献
32.
Gold nanoparticles in aqueous dispersion were prepared using the trisodium citrate reduction method to control the size of
particles by changing the concentration of HAuCl4. The average particle size measured by DLS is higher than that obtained by TEM at a zeta potential of -40 mV. When trisodium
citrate concentration is kept constant, the particle size increases with gold concentration. The kinetics of growth was studied
and apparent kinetic rate constants were determined at various gold/citrate ratios. Gold nanoparticles were attached to silanized
glass surfaces; Au rods were grown (ca. 200 nm) by adding more precursors and the rods’ growth rate was monitored by UV-Vis
spectroscopy as well as by AFM. Surface functionalization of gold surface was influenced by cysteine. The surface modification
by cysteine at pH=6.0 results in aggregation and the red shift of absorption maximum is nearly 200 nm. When glutathione molecules
are bound onto the cysteinelinked Au rods on the glass surface, the spectral shift reaches only an amount of 5–10 nm, because
the surface attachment hinders the tendency to aggregate. 相似文献
33.
Various methods of separating technetium from molybdenum anhydride irradiated with thermal neutrons in a nuclear reactor have been investigated. A method has been devised and tested In laboratory conditions for the concentration and separation of technetium, based on the co-precipitation of technetium with difficultly soluble phosphates and on Chromatographic purification. Milligram quantities of Tc99 have been obtained by this method. The separated technetium has been identified by means of spectrum analysis, and the absolute activity and maximum energy of its ß -radiations have also been measured. Some chemical properties of technetium have been studied.Presented on March 9, 1957 at the All-Union Radiochemistry Conference in Leningrad. 相似文献
34.
Renáta Oriňaková Radka Gorejová Viktória Čákyová Miroslav Džupon Miriam Kupková Tibor Sopčák Kadir Özaltin Matej Mičušík Ondrej Petruš Mária Omastová Marek Vojtko Petr Sáha 《应用聚合物科学杂志》2024,141(2):e54773
Over the last decades, biodegradable metals have gained popularity for biomedical applications due to their ability to assist in tissue healing. These materials degrade in vivo, while the corrosion products formed are either absorbed or excreted by the body, and no further surgical intervention is required for removal. Intensive research has been carried out mainly on degradable biomaterials based on Mg and Fe. In recent years, zinc-based degradable biomaterials have been explored by the biomedical community for their intrinsic physiological relevance, desirable biocompatibility, intermediate degradation rate, tuneable mechanical properties and pro-regeneration properties. Since pure Zn does not exhibit sufficient mechanical properties for orthopedic applications, various Zn alloys with better properties are being developed. In this work, the combined effect of minor Fe addition to Zn and a polyethyleneglycol (PEG) coating on the surface morphology, degradation, cytotoxicity and mechanical properties of Zn-based materials was studied. There are several studies regarding the influence of the production of Zn alloys, but the effect of polymer coating on the properties of Zn-based materials has not been reported yet. A positive effect of Fe addition and polymer coating on the degradation rate and mechanical properties was observed. However, a reduction in biocompatibility was also detected. 相似文献