Astrakhan State University

About: Astrakhan State University is a education organization based out in Astrakhan, Russia. It is known for research contribution in the topics: Percolation & Carbamate. The organization has 547 authors who have published 565 publications receiving 2367 citations.

Synthesis and Antimicrobial Activity of Substituted Nitrotetrazole-5-Carbaldehyde Hydrazones

Abstract: A series of substituted -nitrotetrazole-5-carbaldehyde hydrazones were synthesized and tested for antimicrobial activity with respect to Staphylococcus aureus, Streptococcus pneumoniae, E. coli, P. aeruginosa, and Micrococcus. The minimum inhibitory concentrations were determined.

Virtual network as excitable medium

Abstract: We simulated the spread of an activity in a virtual group using the model of excitable medium. We assumed that the structure of the virtual group corresponds to a scale- free network. In our simulation, the network consists of 100 nodes, the average degree of the nodes is 1.98. We considered the propagation of excitation both in a homogeneous and an inhomogeneous excitable medium. The simulation showed that the initial conditions have a little effect on the behaviour of the model. In inhomogeneous medium, fraction of the excited nodes increases, when permanent excited elements ('active' centres) appear in the network. The fraction of the excited nodes increases, when we increase the number of the permanent excited elements. Locations of the active centres do not affect at the level of excitation. External source of activator increases the fraction of the excited nodes in the scale-free network with distribution of parameters.

Nitration of styrenes using 2-methyl-5-trinitromethyltetrazole

Abstract: Details of the methods of synthesis, chemical properties, and practical importance of tetrazoles have been reported in the studies [1, 2] and in a series of reviews [3-5]. At the same time, the chemical transformations of 5-trinitromethyltetrazoles have been investigated to a lesser degree. It is only known that 5-trinitromethyl-1H-tetrazole is denitrated in the presence of an alkaline solution of hydroxylamine to give the potassium salt of 5-dinitromethyltetrazole, while its reaction with excess diazomethane results in the formation of a mixture of the isomeric 5-(1-methyltetrazolyl)and 5-(2-methyltetrazolyl)trinitromethanes [6]. We have found that 2-methyl-5-trinitromethyltetrazole (1) reacts with the styrenes 2a-d as a nitrating agent. The reaction of tetrazole 1 with the ethenes 2a-d in a neutral medium results in the denitration of compound 1 to give the -nitro ketones 3a-c (from the alkenes 2a-c) or the 1-methyl-2-nitro-1-phenyl-1-ethanol 3d (from alkene 2d). In addition, the degradation products of compound 1 (the nitromethanone oxime 4 from the reactions with compounds 2a-c or the 5-dinitromethyltetrazole 5 from the reaction with compound 2d) are formed in low yields.

Heart Rate Variability in Nonlinear Rats with Different Orientation and Exploratory Activity in the Open Field.

Abstract: The basic behavioral activity of nonlinear rats was evaluated from the sum of crossed peripheral and central squares and peripheral and central rearing postures in the open fi eld test. This index was low ( 30 episodes). Male rats with high score of orientation and exploratory activity were characterized by higher indexes of total heart rate variability than rats with low or intermediate activity. Specimens with a greater contribution of VLF waves into the total power spectrum of heart rate variability were shown to dominate among the rats with high behavioral activity. Our results are consistent with the notions of a suprasegmental nature of VLF waves.

Synthesis of new functionally substituted hetarylcarbamates from methyl {4-[(2E)-3-(4-methoxyphenyl)-prop-2-enoyl]phenyl}carbamate

Abstract: Three-component condensation of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}- carbamate with ninhydrin and L-proline in methanol–water (10: 1) afforded methyl {4-[1,3-dioxo-1′- (4-methoxyphenyl)-1,1′,2′,3,5′,6′,7′,7a′-octahydrospiro[indene-2,3′-pyrrolizin]-2′-ylcarbonyl]phenyl}carbamate. Heating of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}carbamate with isatin and benzylamine in methanol gave methyl {4-[4′-(4-methoxyphenyl)-2-oxo-5′-phenyl-1,2-dihydrospiro[indole-3,2′-pyrrolidin]-3′-ylcarbonyl]phenyl}carbamate. The condensation of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2- enoyl]phenyl}carbamate with sarcosine and 11H-indeno[1,2-b]quinoxalin-11-one generated in situ from ninhydrin and o-phenylenediamine in boiling ethanol led to the formation of methyl {4-[4′-(4-methoxyphenyl)-1′-methyl-11,11a-dihydro-5aH-spiro[benzo[b]phenazine-6,2′-pyrrolidin]-3′-ylcarbonyl]phenyl}carbamate.