Ultraviolet irradiation of terarylenes: A facile,efficient, and environmentally friendly method for the synthesis of fused polycyclic products

Ultraviolet irradiation of hydroxyl substituted terarylenes provided a simple, efficient, and environmentally friendly method for the synthesis of imidazo[1,2-a]pyridines. The starting terarylenes were prepared via the one-pot, three-component condensation of readily accessible arylglyoxals, 2-aminopyridines, and dimedone.     

Luminescent Mono-, Di-, and Triradicals: Bridging Polychlorinated Triarylmethyl Radicals by Triarylamines and Triarylboranes

Up to three polychlorinated pyridyldiphenylmethyl radicals bridged by a triphenylamine carrying electron withdrawing (CN), neutral (Me), or donating (OMe) groups were synthesized and analogous radicals bridged by tris(2,6-dimethylphenyl)borane were prepared for comparison. All compounds were as stable as common closed-shell organic compounds and showed significant fluorescence upon excitation. Electronic, magnetic, absorption, and emission properties were examined in detail, and experimental results were interpreted using DFT calculations. Oxidation potentials, absorption and emission energies could be tuned depending on the electron density of the bridges. The triphenylamine bridges mediated intramolecular weak antiferromagnetic interactions between the radical spins, and the energy difference between the high spin and low spin states was determined by temperature dependent ESR spectroscopy and DFT calculations. The fluorescent properties of all radicals were examined in detail and revealed no difference for high and low spin states which facilitates application of these dyes in two-photon absorption spectroscopy and OLED devices.     

Autosolitons in dispersion-managed systems with in-line saturable absorbers

We study the formation of stable solitonlike pulses in dispersion-managed fiber transmission systems using an in-line fast saturable absorber. Operational regimes suitable for 40-Gbit/s channel rate transmission are demonstrated.     

Microbial enzymes mined from the Urania deep-sea hypersaline anoxic basin

We created a metagenome expression library from the brine:seawater interface of the Urania hypersaline basin, screened it for esterases, and characterized five of these. Two had no significant sequence homology to known esterases, hydrolyzed both carboxylesters and thioesters, and exhibited unusual, habitat-specific characteristics (preference for high hydrostatic pressure and salinity). One has an unusual structural signature incorporating three catalytic active centers mediating distinct hydrolytic activities and an adaptive tertiary-quaternary structure that alters between three molecular states, according to the prevailing physicochemical conditions. Some of the esterases have high activities, specificities, enantioselectivities, and exceptional stability in polar solvents, and they are therefore potentially useful for industrial biotransformations. One possesses the highest enantioselectivity toward an ester of the important chiral synthon solketal (E: 126[S]; 98%ee).     

On coupling of stochastic processes with embedded point processes

Criteria for semi-, wide-sense-, traditional regeneration and a coupling construction of stochastic processes with embedded point processes are presented.     

Physical models of cognition

This paper presents and discusses physical models for simulating some aspects of neural intelligence, and, in particular, the process of cognition. The main departure from the classical approach here is in utilization of a terminal version of classical dynamics introduced by the author earlier. Based upon violations of the Lipschitz condition at equilibrium points, terminal dynamics attains two new fundamental properties: it is spontaneous and nondeterministic. Special attention is focused on terminal neurodynamics as a particular architecture of terminal dynamics which is suitable for modeling of information flows. Terminal neurodynamics possesses a well-organized probabilistic structure which can be analytically predicted, prescribed, and controlled, and therefore which presents a powerful tool for modeling real-life uncertainties. Two basic phenomena associated with random behavior of neurodynamic solutions are exploited. The first one is a stochastic attractor—a stable stationary stochastic process to which random solutions of a closed system converge. As a model of the cognition process, a stochastic attractor can be viewed as a universal tool for generalization and formation of classes of patterns. The concept of stochastic attractor is applied to model a collective brain paradigm explaining coordination between simple units of intelligence which perform a collective task without direct exchange of information. The second fundamental phenomenon discussed is terminal chaos which occurs in open systems. Applications of terminal chaos to information fusion as well as to explanation and modeling of coordination among neurons in biological systems are discussed. It should be emphasized that all the models of terminal neurodynamics are implementable in analog devices, which means that all the cognition processes discussed in the paper are reducible to the laws of Newtonian mechanics.     

Two types of chaos in non-linear mechanics

Two types of chaos are associated with the Hadamard and Liapunov instabilities, respectively. Their criteria and peculiarities are analyzed.     

On the Codimension Growth of Finite-Dimensional Lie Algebras

We study the exponential growth of the codimensions c_n(L) of a finite-dimensional Lie algebra L over a field of characteristic zero. We show that if the solvable radical of L is nilpotent then exists and is an integer.     

Chemical Morphing of DNA Containing Four Noncanonical Bases

The ability of alternative nucleic acids, in which all four nucleobases are substituted, to replicate in vitro and to serve as genetic templates in vivo was evaluated. A nucleotide triphosphate set of 5‐chloro‐2′‐deoxyuridine, 7‐deaza‐2′‐deoxyadenosine, 5‐fluoro‐2′‐deoxycytidine, and 7‐deaza‐2′deoxyguanosine successfully underwent polymerase chain reaction (PCR) amplification using templates of different lengths (57 or 525mer) and Taq or Vent (exo‐) DNA polymerases as catalysts. Furthermore, a fully morphed gene encoding a dihydrofolate reductase was generated by PCR using these fully substituted nucleotides and was shown to transform and confer trimethoprim resistance to E. coli. These results demonstrated that fully modified templates were accurately read by the bacterial replication machinery and provide the first example of a long fully modified DNA molecule being functional in vivo.     

Electrocatalytic multicomponent transformation of cyclic 1,3-diketones, isatins, and malononitrile: facile and convenient way to functionalized spirocyclic (5,6,7,8-tetrahydro-4H-chromene)-4,3′-oxindole system

An electrochemically induced catalytic multicomponent transformation of cyclic 1,3-diketones, isatins, and malononitrile in alcohols in an undivided cell in the presence of sodium bromide as an electrolyte results in the formation of spirooxindoles with fused functionalized 5,6,7,8-tetrahydro-4H-chromene system in 83-98% yields. The application of this efficient electrocatalytic method to the formation of medicinally relevant spirocyclic (4H-chromene)-4,3′-oxindoles is beneficial from the viewpoint of diversity-oriented large-scale processes and represents novel, facile, and environmentally benign synthetic concept for multicomponent reaction strategy.