Colloid-chemical properties and physiological activity of water-soluble humic preparations

Conditions were found for solid-phase mechanochemical activation of coals, allowing a significant increase in the yield of water-soluble humic preparations enriched in humic acids and mineral elements. The humic preparations are characterized by a decrease in the molecular mass and by changes in the ionic composition and surface activity. The physiological activity of the humic preparations was determined.     

Organoruthenium derivative of the cyclic [H7P8W48O184]33- anion: [{K(H2O)}3{Ru(p-cymene)(H2O)}4P8W49O186(H2O)2]27-

Reaction of [Ru(p-cymene)Cl2]2 with [H7P8W48O184]33- (P8W48) in aqueous acidic medium results in the organometallic derivative [{K(H2O)}3{Ru(p-cymene)(H2O)}4P8W49O186(H2O)2]27- (1); in addition to the four {Ru(p-cymene)(H2O)} units, an unusual WO6 group with four equatorial, terminal ligands is also grafted to the crown-shaped P8W48 precursor.     

Composition, structure, and luminescence of montmorillonites saturated with different aggregates of methylene blue

The distribution of various aggregates (dimers, trimers, and tetramers) of methylene blue (MB) formed in aqueous solution at various concentrations of dye has been calculated using the equilibrium aggregation constants betaq. Two montmorillonite samples with different cation exchange capacities, surface areas, and interlayer distances d001, Na-SWy, and Ca-Cheto, were saturated with methylene blue (MB) solutions with various ratios between monomers and higher aggregates of dye. The total amount of MB in the intercalated montmorillonite samples (MB-SWy and MB-Cheto) increases with increasing concentration of dye in water solutions, i.e., with increasing aggregates/monomers ratio of MB in water solution. In all intercalated montmorillonite samples with methylene blue except guest qth aggregate cations [MBqq+] low contents of Na+ (in MB-SWy) and Ca2+ (in MB-Cheto) cations were also determined. A very good positive correlation between the basal spacing d001 and the MB/montmorillonite molar ratio was revealed for saturated MB-montmorillonite samples. Structural analysis using a combination of diffraction data with molecular modeling revealed the differences in the interlayer arrangement of MB guests in MB-SWy and MB-Cheto intercalates. Also, fluorescence measurements showed the strong effect of the silicate layer charge on the spectroscopic behavior of MB guests intercalated in montmorillonite. Methylene blue exhibits a certain luminescence in MB-SWy samples with cation exchange capacity 0.80 meq g-1 and almost no luminescence in MB-Cheto samples with higher cation exchange capacity 1.50 meq g-1.     

Manifold constrained variational problems

The integral representation for the relaxation of a class of energy functionals where the admissible fields are constrained to remain on a -dimensional manifold is obtained. If is a continuous function satisfying for and for all then where is open, bounded, and is the tangential quasiconvexification of f at belong to the tangent space to at Received October 10, 1998 / Accepted December 1, 1998     

Exact results of statistical analysis of multichannel adaptive systems with continuous gradient algorithms

We obtained some exact expressions for the power of the output signal of adaptive systems with continuous gradient adjustment algorithms. It is shown that fluctuations of weight coefficients result in a decrease in the signal power at the adaptive-system output as compared with the output-signal power in the absence of fluctuations of the weight coefficients. The “overcompensation” phenomenon is explained by the presence of a non-Gaussian statistical relation between the weight- coefficient and input-signal vectors. N. I. Lobachevskii State University, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 9, pp. 914–921, September, 1999.     

T3P-Promoted Synthesis of a Series of 2-Aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones and Their Activity against the Kinetoplastid Parasite Trypanosoma brucei

A series of fourteen 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-phenyl-C-aryl imines with thionicotinic acid, two difficult substrates. The reactions were operationally simple, did not require specialized equipment or anhydrous solvents, could be performed as either two or three component reactions, and gave moderate–good yields as high as 63%. This provides ready access to N-phenyl compounds in this family, which have been generally difficult to prepare. As part of the study, the first crystal structure of neutral thionicotinic acid is also reported, and showed the molecule to be in the form of the thione tautomer. Additionally, the synthesized compounds were tested against T. brucei, the causative agent of Human African Sleeping Sickness. Screening at 50 µM concentration showed that five of the compounds strongly inhibited growth and killed parasites.     

Infrared spectroscopy of europium borates Eu<Emphasis Type="Italic">M</Emphasis><Subscript>3</Subscript>(BO<Subscript>3</Subscript>)<Subscript>4</Subscript> (<Emphasis Type="Italic">M</Emphasis> = Al,Cr, Fe,Ga) with a huntite mineral type of structure

Huntite-like EuM ₃(BO₃)₄ crystals (M = Al, Cr, Fe, or Ga) are synthesized by means of spontaneous crystallization from a solution in a melt. The infrared spectra of the compounds are measured. The experimental data and the results from ab initio DFT calculations are compared. The comparison shows that the compounds have a primarily noncentrosymmetric rhomboherdal structure with the R32 space group. This indicates these compounds could exhibit magnetoelectric and nonlinear optical properties.     

Notes on selectivity aspects in sorbic acid and sorbic alcohol hydrogenation

Sorbic acid and sorbic alcohol hydrogenations to the cis-hex-3-enoic acid or cis-hex-3-en-1-ol were carried out at the same conditions in three different systems—homogeneous, two-phase and heterogeneous. The complex [Cp*Ru(sorbic acid)]CF₃SO₃ was used as a catalyst. Selectivity and reactivity of both the compounds varied significantly. Using sorbic acid as a hydrogenation substrate by-products were the other izomers of hexenoic acid and hexanoic acid, with sorbic alcohol as a hydrogenation substrate by-products were aldehydes and hemiacetals.