Complex formation of chitosan with amikacin and gentamicin antibiotics

Complex formation of chitosan with Amikacin and Gentamicin antibiotics was studied. The optimal conditions for preparing the complexes were found.     

On the properties of “short” granular magnets with disordered chains of grains: A field between grains

The values and functional exponential form of the demagnetizing factor of “short” cylindrical samples of the polyspherical medium and samples (elements) of this medium, i.e., chains of spheres, have been established. The tortuosity factor of chains formed by spheres (as effective elementary conductors of the magnetic flux in a magnetized granular medium) has been analyzed. It has been demonstrated that the tortuosity factor for chains in a filling medium is insignificant. The strength of the field between spheres in the chain, like the magnetic permeability of the effective magnetization channel, has an extremum (bell-shaped) profile. It has been revealed (by using magnetophoresis of finely dispersed ferroparticles) that the gradient of this strength exhibits a two-extremum profile.     

Solution of the Dirichlet problem for a singularly perturbed reaction-diffusion equation in a square on a Bakhvalov grid

The Dirichlet problem for a singularly perturbed reaction-diffusion equation in a square is solved with the help of the classic five-point difference scheme and a grid that is the tensor product of 1D Bakhvalov grids. Without imposing additional matching conditions in the corners of the domain, it is shown that the grid solution to the problem has the accuracy O(N ⁻²) in the norm L _∞ ^h , where N is the number of grid nodes along each direction. The accuracy is uniform with respect to a small parameter. A simulation confirms the theoretical prediction.     

The first example of an intramolecular Diels-Alder furan (IMDAF) reaction of iminium salts and its application in a short and simple synthesis of the isoindolo[1,2-a]isoquinoline core of the jamtine and hirsutine alkaloids

1-(2-Furyl)-3,4-dihydroisoquinolines, easily prepared from readily available phenethylamines, undergo tandem alkylation/[4+2]-cycloaddition with allyl halides. The reaction proceeds via 2-allyl-1-furyl-3,4-dihydroisoquinolinium salt formation and subsequent intramolecular exo-Diels-Alder reaction of furan with the allyl fragment (IMDAF reaction). The adducts formed include the basic structural element of the isoindolo[1,2-a]isoquinoline alkaloids jamtine and hirsutine.     

Effect of Surfactants on the Immobilization of 4-(2-Pyridylazo)resorcinol on Silochroms

The effect of cationic surfactants (cetyltrimethylammonium bromide, cetylpyridinium bromide, and tetrabutylammonium perchlorate) and a nonionic surfactant (OP-7) on the conditions of the immobilization of 4-(2-pyridylazo)resorcinol (PAR) on three types of silica gel (Silochrom S-120 (200–350 m), Silochrom S-120 (315–500 m), and Silochrom S-80 (200–350 m)) was studied. It was found that OP-7 does not affect the adsorption of surfactants. The effect of cationic surfactants increases in the order tetrabutylammonium perchlorate < cetyltrimethylammonium bromide < cetylpyridinium bromide. The adsorption activity of silica gels increases in the order Silochrom S-120 (315–500 m) < Silochrom S-80 (200–350 m) < Silochrom S-120 (200–350 m). Cetylpyridinium bromide provides full immobilization of PAR on silica gel Silochrom S-120 (200–350 m) in the pH range 2–9.     

Chromaticity characteristics of iron (II, III) complexes with 1-nitroso-2-naphthol-3,6-disulfonic acid

Optimal conditions for the complexation of iron(II, III) with 1-nitroso-2-naphthol-3,6-disulfonic acid in two buffer solutions and the reduction of iron(III) with ascorbic acid or hydroxylamine were found by spectrophotometry and chromaticity measurements. Chemical analytical and chromaticity characteristics of complexes in solutions were determined. It was shown that two complexes formed depending on the oxidation state of iron. Molar coefficients of the chromaticity functions were 20 to 30 times higher than molar absorption coefficients. The complexes exhibited abnormal light absorption maxima (710–720 nm) among the known 1-nitroso-2-naphthol-3,6-disulfonates and were chemically inert, which offers promise for analytical purposes.     

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.     

Synthesis and insectoacaricidal activity of S-benzhydryl esters of phosphorus dithio- and monothioacids

Conclusions We synthesized a number of S-benzhydryl esters of phosphorus dithioacids that possess insectoacaricidal properties, in which connection the most active ester, O-ethyl S-benzhydryl methyldithiophosphonate, has the same contact activity as Chlorophos and Rogor.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2170–2172, September, 1978.