Separation and purification of isoflavones from Pueraria lobata by high-speed counter-current chromatography.

High-speed counter-current chromatography (HSCCC) was applied to the semipreparative separation and purification of puerarin and related isoflavones from a crude extract of Pueraria lobata. Analytical HSCCC was used for the preliminary selection of a suitable solvent system composed of ethyl acetate-n-butanol-water (2:1:3, v/v/v). Using the above solvent system the preparative HSCCC was successfully performed yielding six relatively pure isoflavones including puerarin from 80 mg of the crude extract in one-step separation.     

Perovskite-sensitized solar cell utilizing TiO2 nanograss: Effect of dipping time of CH3NH3PbI3 perovskite

Organic perovskite has potential to replace organic dye as light absorber in solar cell since it possesses better optical absorption in visible region than organic dye. This work is concerned with the investigation of the influence of CH₃NH₃PbI₃ perovskite dipping time on the performance of perovskite-sensitized solar cell (PSSC). The effect of the dipping time on the morphology and photoluminescence of the sample has also been investigated. It was found that the device achieved a power conversion efficiency (PCE) as high as 5.57 ± 0.4% at the optimum dipping time of 4 h. The highest PCE is due to the highest IPCE, lowest R_ct and the longest carrier lifetime (τ).     

Peculiarities of pendellösung fringes in quartz monocrystals

The scattering of X-rays in quartz monocrystals has been investigated. It has been discovered experimentally, that even for the thick quartz crystals, for which μt = 5, pendular bands can be obtained. The appearance of pendular bands depending on the crystal thickness, the reflecting plane families and the reflection order, was investigated as well.     

Complex Study of the Spearhead Superficial Crust from Burial Mound no. 1 near Novosvobodnaya Village

A complex study of a spearhead dated back to IV mill. BC from burial mound no. 1 near Novosvobodnaya village (collection of the State Historical Museum) and, in particular, the material of spearhead superficial crust has been performed. The elemental and phase composition of the metal of spearhead and the superficial crust on its surface have been determined by scanning electron microscopy, jointly with energydispersive X-ray microanalysis and X-ray phase analysis. A comparative analysis of the results of studying the spearhead superficial crust and similar crusts on other artifacts from the mounds near Novosvobodnaya village suggest natural origin of the crust on copper?arsenic artifacts.

     

Global Stability Results for the Weak Vector Variational Inequality

In this paper, we consider the global stability of solutions of a Weak Vector Variational Inequality in a finite-dimensional Euclidean space. Upper semi-continuity of the solution set mapping is established. And by a scalarization method, we derive a sufficient condition that guarantees the lower semi-continuity of the solution set mapping for the Weak Vector Variational Inequality