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Mechanical properties of cells depend on various external and internal factors, like substrate stiffness and surface modifications, cell ageing and disease state. Some other currently unknown factors may exist. In this study we used force spectroscopy by AFM, confocal microscopy and flow cytometry to investigate the difference between single non-confluent and confluent (in monolayer) Vero cells. In all cases the stiffness values were fitted by log-normal rather than normal distribution. Log-normal distribution was also found for an amount of cortical actin in cells by flow cytometry. Cells in the monolayer were characterized by a significantly lower (1.4-1.7 times) Young's modulus and amount of cortical actin than in either of the single non-confluent cells or cells migrating in the experimental wound. Young's modulus as a function of indentation speed followed a weak power law for all the studied cell states, while the value of the exponent was higher for cells growing in monolayer. These results show that intercellular contacts and cell motile state significantly influence the cell mechanical properties. [ABSTRACT FROM AUTHOR]

2,2,2-Trichloro-4-fluoro-1,3,2?5-benzodioxaphosphole reacts with phenylacetylene to give 2,7-dichloro-5-fluoro-4-phenyl-2H-1,2?5-benzoxaphosphinine 2-oxide. Hydrolysis of the latter leads to opening of the oxaphosphinine ring with formation of (E)-2-(4-chloro-2-fluoro-6-hydroxyphenyl)-2-phenylethenylphosphonic acid. [ABSTRACT FROM AUTHOR]

2-Sulfanylethanol was added to readily available 1-alkyl 3,5-diallyl isocyanurates to obtain 1-alkyl 3,5-bis[3-(2-hydroxyethylsulfanyl)propyl] isocyanurates. Treatment of the products with thionyl chloride gave 1-alkyl 3,5-bis[3-(2-chloroethylsulfanyl)propyl] isocyanurates whose reaction with thiourea followed by hydrolysis resulted in preparation 1-alkyl 3,5-bis[3-(2-sulfanylethylsulfanyl)propyl] isocyanurates. Oxiative cyclization of the latter gave macrocyclic disulfides in 56-75% yields. The composition and structure of the macrocyclic disulfides were established on the basis of the elemental and X-ray diffraction analyses,1H and13C NMR and IR spectra, as well as MALDI-TOF and electron impact mass spectra. [ABSTRACT FROM AUTHOR]

The origin of the peculiar stellar complex in the outskirts of the spiral galaxy NGC 6946 is discussed. The complex hosts a superstar cluster, two dozen smaller bright clusters and many high-luminosity stars 5–30 Myears old. In spite of this, no features in H I or CO are associated with the complex. The most simple explanation is that the complex is a foreground blue compact galaxy, a member of the NGC 6946 group. The arc of high light absorption along the complex rim could then be the result of the ram pressure of the intergalactic medium gas. The existing velocity data cannot prove or disprove this hypothesis. [ABSTRACT FROM AUTHOR]

The basic characteristics of stellar complexes and superassociations, as well as the differences between these kinds of gigantic groups of young stars, are discussed. The main difference is that superassociations are the result of induced (triggered) star formation, while the stars and clusters in stellar complexes develop as a result of the spontaneous processes typical of galactic gaseous disks. [ABSTRACT FROM AUTHOR]

A number of 3-R-9-(2-oxopropyl)-1,5-dinitro-7,8-benzo-3-azsbicyclo[3.3.1]non-7-en-6-ones was synthesized by Mannich reaction involving Yanovsky adduct of 2,4-dinitronaphthol. It was established by molecular spectroscopy and X-ray diffraction analysis that the piperidine ring in these compounds was in the chairconformation with a diequatorial position of the substituent attached to the heteroatom and 2-oxo-propyl group, and the cyclohexenone fragment was in sofaform. By an example of 3-methyl-9-(2-oxopropyl)-1,5-dinitro-7,8-benzo-3-azsbicyclo[3.3.1]non-7-en-6-one the dissociative ionization of bicyclononanes under the electron impact was investigated. [ABSTRACT FROM AUTHOR]

A method for estimating the influence of operational mode parameters of a turbo-generator unit on its vibrational state is proposed and recommended for application in the automated vibration- monitoring system for turbo-generator rotors. Correlation and graphic methods are applied for determining the interrelation between the operational mode parameters and vibrational characteristics of a turbo-generator unit. Results of full-scale investigations on the vibrational state kinetics of the generator in variation of its power consumption are presented. [ABSTRACT FROM AUTHOR]

We have made a new comparison of the positions of Cepheids and clusters in the LMC and constructed a new empirical period–age relation taking into account all available data on Cepheids in the LMC bar provided by the OGLE project. The most probable relation is log T = 8.50–0.65 log P, in reasonably good agreement with theoretical expectations. Numerous Cepheids in rich clusters of the LMC provide the best data for comparing theories of stellar evolution and pulsation and the dynamical evolution of clusters with observations. These data suggest that stars undergoing their first crossing of the instability strip are first-overtone pulsators, though the converse is true of only a small fraction of first-overtone stars. Several rich clusters with suitable ages have no Cepheids—a fact that is not understood and requires verification. Differences in the concentration of Cepheids toward their cluster centers probably reflect the fact that the clusters are at different stages of their dynamical evolution, with the Cepheids in cluster coronas being ejected from the cluster cores during dynamical interactions between stars.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

A series of 7-carboxy-3-R-1,5-dinitro-3-azabicyclo[3.3.1]non-6-enes was synthesized by reduction of 3,5-dinitrobenzoic acid with sodium borohydride followed by Mannich reaction with formaldehyde and primary amines. The mechanism of decomposition under electron impact of the 3-azabicyclo[3.3.1]nonane was established. Enthalpies of formation of compounds synthesized were calculated by semiempirical PM3 method. [ABSTRACT FROM AUTHOR]

The nature of stellar complexes with peculiar populations and morphologies is investigated. The existence in the LMC of complexes made up of isolated stars, on the one hand, and consisting exclusively of clusters, on the other hand, could be due to different turbulence patterns in the initial gaseous medium. Arc-shaped stellar complexes are unlikely to be the result of star formation in a gaseous shell swept up by a central source of pressure, and instead probably reflect the shape of a bow shock that develops when a sufficiently dense cloud is subject to dynamical pressure. A peculiar arc-shaped complex in NGC 6946, which contains a young, massive cluster, may be the result of an oblique infall of a high-velocity cloud onto a region of the gaseous disk of the Galaxy with a strong, regular magnetic field; the properties of this complex can be explained as the result of a collision of the resulting shocks. The arc-shaped complexes in the LMC were also probably produced by high-velocity clouds moving obliquely through the more tenuous gas of the LMC disk. A similar complex in NGC 300 may owe its origin to the effect produced on a dense cloud by the shock from an extremely powerful external explosion, whose stellar remnant may have survived as an X-ray source now located along the line of symmetry of the arc of the complex. The rareness of such structures can be explained by the narrow range of conditions under which they can develop.© 2002 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

A new macrocycle including pyrimidine fragments, 12,23,36-trimethyl-24,40-dioxo-15,33-dithia-2,9,13,22,26,35,38,39-octaazatetracyclo[32.3.1.110,14.122,26]tetraconta-1(38),10(39),11,13,23,34,36-heptaene, was synthesized. According to the data of IR and UV spectroscopy and HF/6-31G** quantum-chemical calculations, macrocyclic compounds of this series in crystal exist in the amino form, one NH group of which is likely to be involved in intramolecular hydrogen bond, and the other, in intermolacular hydrogen bond. The strength of the latter depends on the macroring size. In solution, the above structures are supplemented by conformers containing both intramolecularly H-bonded and free amino groups, predominantly with trans structure of the HÄNÄCÍN fragment. The imino form of the aminopyrimidine moieties is hardly probable. [ABSTRACT FROM AUTHOR]

When 3-( a-thiocyanobenzyl-2(1H)-one is heated, competing processes of [ a]-annelation of the imidazole or thiazole rings occurs with formation of imidazo[1,5- a]- and thiazolo[3,4- a]quinoxalin-4(5H)-ones. [ABSTRACT FROM AUTHOR]

Complexes of young clusters and high-luminosity stars in the shape of regular, circular arcs have been found in a number of galaxies, first and foremost the LMC, NGC 6946, and M83. These shapes are found even in strongly inclined galaxies, suggesting that the observed arcs are projections of partial spherical shells. Obviously, these stellar shells must have formed from gaseous shells swept up by some source of central pressure and become gravitationally unstable. The power of this source corresponds to several dozen supernova explosions; however, its nature remains unclear. A central cluster providing a source of O stars and supernovae is usually absent. The presence of multiple arcs located close to each other can be explained by the fall of a swarm of fragments or by the progenitor stars originating in a single peculiar star cluster, implying the existence of stellar objects capable of giving rise to explosions with energies an order of magnitude higher than those of individual supernovae. The same objects may be responsible for gamma-ray bursts. It may be that only the most massive clusters with frequent or especially powerful supernova explosions are capable of producing HI supershells. Otherwise, it is impossible to explain why no supershells have been found around numerous clusters that should be capable of producing them according to current theories. The presence of star clusters in shell-like structures provides extremely important information about the physical conditions in and the ages of the initial gaseous shells, making stellar arcs the best available laboratory for studies of triggered star formation. [ABSTRACT FROM AUTHOR]

Two independent sets of arguments lead us to conclude that the progenitors of superintense bursts (with an energy yield larger than that for ordinary supernovae by one or two orders of magnitude) are born in massive dense star clusters, but generally flare up only after they have left the cluster; these are the same objects that are the progenitors of gamma-ray bursts (GRBs). Each of the giant stellar arcs which are grouped into multiple systems of stellar complexes in the LMC and NGC 6946 could only be produced by a single powerful energy release near its center. The progenitors of these systems of arc-shaped stellar complexes must have had a common source nearby, and it could only be a massive star cluster. Such clusters are actually known near both systems. On the other hand, calculations of the dynamical evolution of star clusters show that close binary systems of compact objects are formed in the dense central parts of the clusters and are then ejected from them during triple encounters. Mergers of the components of such systems are believed to be responsible for GRBs. Since their progenitors are ejected from the cluster before merging, the arc-shaped stellar complexes produced by GRBs are observed near (but not around) the parent clusters. If a considerable fraction of the GRB progenitors are formed as a result star encounters in massive star clusters, and if the GRBs themselves trigger star formation near the parent clusters, then observations of GRBs in star-forming regions are consistent with their origin during mergers of pairs of compact objects. [ABSTRACT FROM AUTHOR]

The reaction of [60]fullerene with diphenylphosphinoyl azide in toluene or in o-dichlorobenzene in the presence of traces of water affords 2-[ N-(diphenylphosphoryl)amino]-1-hydroxy[60]fullerene This reaction in THF gives a mixture of ( N-diphenylphosphoryl)[60]fullerenol[1,2- b]aziridine and a product of partial hydrolysis of the bisadduct of phosphorylated azide and fullerene. [ABSTRACT FROM AUTHOR]

Methods have been developed for dehydrating the unusually stable intermediate products of the Hantzsch reaction of N,N′-diphenylthioureas with derivatives of phenylchloropyruvic acid, viz. 4-hydroxy-4-methoxy (diethylamino)carbonyl-3,5-diphenyl-2-phenyliminothiazolidines, into the corresponding 4-methoxy-(diethylamino) carbonyl-3,5-diphenyl-2-phenyliminothiazolines. Characteristic features of the dissociative ionization of the latter and their anilide analog under the action of electron impact have been clarified. [ABSTRACT FROM AUTHOR]