Clarification of a dilute suspension of calcium carbonate in the presence of Praestol flocculants and aluminum sulfate coagulant

Russian Journal of Applied Chemistry - Kinetic features of clarification of 1% suspension of calcium carbonate under the action of coagulants (aluminum sulfate, hydroxoaluminum chloride) and...     

Experimental detection and investigation of muon catalyzed fusion of deuterium and tritium

Measurement of the neutron yield of the reaction $\text{dt}\text{μ →}{}^4\text{He}\text{+ μ}{}^{\mathrm{?}}\text{+ 17.6}\text{MeV}$, induced by negative muons in a mixture of gaseous D₂ and T₂, has shown that the rate of muon transfer from deuterium to tritium is λ_dt = (2.7 ± 0.9) × 10⁸s^?1 and that the lower limit of the formation rate of dt_μ molecules is λ_dtμ > 10⁸s^?1.     

AsLn2, a luciferin-related modified tripeptide from the bioluminescent earthworm Fridericia heliota

AsLn2, an unusual modified peptide, was isolated from the bioluminescent earthworm Fridericia heliota (Enchytraeidae). Its structure, elucidated by NMR and mass spectrometry, includes residues of tyrosine, CompX (a novel tyrosine modification product, reported in the accompanying paper), and N(omega)-acylated lysine. Chromatography, UV, and ¹H NMR data imply a close structural similarity of AsLn2 with F. heliota luciferin. AsLn2 appears to be an intermediate or by-product in F. heliota luciferin biosynthesis.     

Stabilization of a concentrated suspension of calcium carbonate with cationic praestol

Russian Journal of Applied Chemistry - The sedimentation stability of a 60% suspension of calcium carbonate in the presence of various commercial samples of cationic Praestol was studied, using a...     

Stabilization of kaolin suspension in the presence of copolymers of sodium 2-acrylamido-2-methylpropanesulfonate with N-vinylpyrrolidone

The kinetics of sedimentation of kaolin suspension in the presence of copolymers of sodium 2-acrylamido-2-methylpropanesulfonate with N-vinylpyrrolidone was studied as influenced by the concentrations, molecular weight, and chemical composition of the copolymer and by the concentration of salts added (NaCl, CaCl₂).     

The spectrum of the photoinduced change in the absorption coefficient of doped Y3Fe5O12 single crystals

For yttrium iron garnet single crystals with different types of majority impurities, the spectra of the photoinduced change in the absorption coefficient α are studied experimentally in the spectral range 0.7–1.9 μm. It is shown that the features of these spectra depend on both the impurity type in the crystal and the spectrum of the illuminating radiation. The experimental results can be explained in terms of the change in the Fe²⁺(Fe⁴⁺) absorption and the changed intensity of optical transitions in the Fe³⁺ ions in the vicinity of charged defects.     

ON THE MECHANISMS OF PHOTOLYSIS OF COMPOUNDS I AND II OF HORSERADISH PEROXIDASE AT 77 K*

Abstract—When Compounds I and II of horseradish peroxidase in glycerol/water glasses at 77 K were irradiated with the light of a mercury lamp, some changes in optical spectra as well as the development of strong EPR signals of a free-radical type were detected. In case of photolysis of Compound I the light of wavelengths around 400 nm was the most effective, while only short wavelength (≥ 280 nm) light affected Compound II. The results of experiments with thawing and freezing the product of photolysis of Compound I (called Intermediate Y) provide further evidence for the suggestion that the ferric state of the heme iron is generated in the course of the photolysis. The quantum yields of the photolysis of Compound I at different wavelengths of irradiating light were obtained and mechanisms of the photolysis of Compounds I and II are proposed.     

Spectral dependence of photoinduced optical absorption in doped yttrium iron garnet single crystals

The photoinduced optical absorption α of doped yttrium iron garnets (YIG) is investigated. It is found that the optical absorption α at a wavelength of 1.1 μm depends on the wavelength of irradiating light in the range 0.6–1.9 μm. It is demonstrated that, in the Y₃Fe₅O₁₂ crystal with an acceptor Ba impurity, the photoinduced increase in α is due to the formation of Fe⁴⁺ ions in octahedral sites. The charge transfer occurs through photoexcitation of the ⁶ A _1g (⁶ S) → ⁴ T _1g (⁴ G) and ⁶ A _1g (⁶ S) → ⁴ T _2g (⁴ G) transitions of octahedral Fe³⁺ ions. In the crystal with a donor Si impurity, the increase in α is caused by the formation of Fe²⁺ ions upon photoionization of silicon. __________ Translated from Fizika Tverdogo Tela, Vol. 43, No. 7, 2001, pp. 1233–1235. Original Russian Text Copyright ? 2001 by Doroshenko, Nadezhdin.