Low-Temperature Predicted Structures of AgS (Silver Sulfide).

Silver sulfide phases, such as body-centered cubic argentite and monoclinic acanthite, are widely known. Traditionally, acanthite is regarded as the only low-temperature phase of silver sulfide. However, the possible existence of other low-temperature phases of silver sulfide cannot be ruled out.

Polymorphic Phase Transformations in Nanocrystalline AgS Silver Sulfide in a Wide Temperature Interval and Influence of Nanostructured AgS on the Interface Formation in AgS/ZnS Heteronanostructure.

Phase transformations that take place in nanocrystalline AgS silver sulfide have been systematically studied at temperatures from 298 to 893 K. The crystal structures of the polymorphic modifications -AgS, -AgS, and -AgS of nanocrystalline AgS have been found. It is established that the interstitial spacings between ions of silver in the superionic phases -AgS and -AgS are noticeably smaller than diameter of the Ag ion.

Elastic properties of superionic cubic silver sulfide β-AgS.

Measurement of heat capacity of superionic silver sulfide (argentite β-Ag2S) revealed that nanocrystalline argentite has a higher heat capacity than coarse-crystalline argentite. It is shown that the heat capacity of nanocrystalline substances includes an additional positive contribution caused by the limitation of the phonon spectrum on the part of low and high frequencies due to a small particle size. The estimation of this contribution on the basis of experimental differences in the heat capacities of nano- and coarse-crystalline argentite β-Ag2S in the region of its existence, 470-850 K, made it possible to determine for the first time the velocities of propagation of longitudinal and transverse elastic vibrations cl and ct and elastic stiffness constants c11, c12 and c44.

Synthesis of AgS colloidal solutions in DO heavy water.

For the first time, colloidal solutions of silver sulfide are synthesized by chemical deposition from solutions of silver nitrate and sodium sulfide in heavy water DO. In the synthesis, sodium citrate was used as a stabilizer. The sizes of AgS quantum dots in colloidal solutions were estimated by dynamic light scattering and transmission electron microscopy.

Cognitive Enhancer Noopept Activates Transcription Factor HIF-1.

The effect of noopept (N-phenylacetyl-L-prolyl-glycine ethyl ester) on the DNA-binding activity of HIF-1 in SH-SH5Y cells and the mechanisms of stabilization of this transcription factor were studied in vitro. Noopept was shown to increase both the basal DNA-binding activity of HIF-1 and the activity induced by various hypoxia mimetics. The mechanism of stabilization of the oxygen-sensitive HIF1α subunit by noopept involves the inhibition of HIF-1 prolyl hydroxylase, which is indirectly indicated by the data obtained using the ODD-Luc reporter, and the positive effect on the level of the HIF1α protein.