Isolation of lappaconitine from Aconitum septentrionale roots by adsorption

Extracts of Aconitum septentrionale Koelle roots obtained using chloroform, isopropanol, and ethanol were purified using chloroform and basic γ-Al₂O₃. Ballast materials were selectively adsorbed by γ-Al₂O₃, increasing the mass fraction of lappaconitine in the extract. The ethanol extract was purified most. The degree of lappaconitine extraction by chloroform was unaffected by the presence of γ-Al₂O₃. However, the mass fraction in the extract and lappaconitine extraction from Aconitum septentrionale were increased more than twice. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 274–276, May–June, 2006.     

Magnetic permeability spectra of nanosized powders of hexaferrites

A study is made of the magnetic permeability spectra of ultrafine W-hexaferrites powders, obtained by mechanical activation. It is demonstrated that natural ferromagnetic resonance frequency can be controlled by mechanochemical treatment. The physical mechanisms of spectrum evolution are discussed.     

Ti-pumped Mo X-ray laser at 24 Å

We propose using the Ti XXI He- emission line to resonantly photo-pump Li-like Mo (Z=42) and produce lasing on several n=5 n=4 transitions near 24 Å. The continuum emission from Ti photoionizes the Mo to the Li-like isoelectronic sequence. Gains of 1–2 cm^–1 are calculated on these lines before the inclusion of Stark broadening which lowers the gain by as much as a factor of two.     

Redetermination of the crystal structure of potassium peroxodisulfate (K2S2O8)

The crystal structure of potassium peroxodisulfate was determined. The crystals are triclinic, a =5.115(1),b =7.034(2), c =5.505(1) å, α =106.32(2),gb =90.18(2), γ =106.12(2)?, V_cell = 181.90(7) å³, space group Pī, Z =1, d_calc =2.468 g/cm ³ [“Syntex P2₁,” λCuK_α, 994 reflections measured in a whole sphere to 2Τ_max =114?, including 496 independent reflections (R_int = 0.0571), R(F) = 0.0391, wR(F²) = 0.0933 for 486 F_hkl > 4Σ(F)]. An absorption correction (Μ = 171.37 cm^?1) was applied taking into account the shape and size of the crystal using data about face indices. The representative of the single crystal was proven by comparing the experimental and calculated diffractograms. The geometrical characteristics of S₂O ₈ ² : S-O 1.645(2), S = 0 1.421(3)-1.429(2), O-O 1.495(5) å, S-O-O 106.2(2)?.     

Crystallization of AgGaS2 melts enriched with Ag2S and Ga2S3

In this work we consider experiments with directed crystallization of melts with slight deviation from stoichiometric composition of AgGaS₂. The evolution of melt composition was calculated for both experiments using measured chemical composition of the solid phase. Also the difference in unit cell parameters and luminescence spectra for AgGaS₂ grown from the melts was found. Both monocrystal samples and samples synthesized from elementary Ag, Ga and S were used for thermal analyses. Obtained data suggests that different ways of preparing the samples are responsible for defects concentration and thus for so wide range (70°C) of melting temperatures reported in scientific literature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,microstructure, and electrochemical performance of Li-rich layered oxide cathode materials for Li-ion batteries

Russian Chemical Bulletin - Li-rich layered oxides Li1.2Mn0.54Ni0.13Co0.13O2 were synthesized by modified Pechini method using various compositions of the reaction mixture. Difference in the...     

Orthorecursive expansions in Hilbert spaces

Orthorecursive expansions over systems of closed subspaces of a Hilbert space are considered. Sufficient conditions for convergence of these expansions to the expanded elements are proved. The results obtained are illustrated on systems of contractions and translations of fixed functions.     

To mechanochemical dimerization of anthracene. Crystalline phenanthrene under high pressure and shear conditions

Calculations at the density functional theory level show that for phenanthrene, unlike anthracene, stable dimeric structures are absent. A study of the absorption and photoluminescence spectra of crystalline phenanthrene under a pressure to 30 kbar and a simultaneous shear reveals reversible changes in the spectra: a shift of absorption bands and luminescence to the long wave region, a decrease in the intensity, and disappearance of the vibrational structure. Unlike anthracene, the dimerization (and other irreversible transformations) of phenanthrene under the simultaneous effect of high pressure and shear is not observed.