Foreword

Structural Chemistry - Milestones of historical evolution of the Chemistry Department of the Lomonosov Moscow State University, which was formally separated from the physical-mathematical faculty...     

Growth of Yb-doped Y2O3, Sc2O3, and Lu2O3 single crystals by the micro-pulling-down technique and their optical and scintillation characterization

In this report, growth of Yb-doped sesqui-oxide crystals of Y₂O₃, Sc₂O₃, and Lu₂O₃ by the micro-pulling-down technique and their scintillation performance are discussed. Growth of these crystals is difficult mostly as a result of their extremely high melting point of around 2400 °C. Nevertheless, appropriate design of the thermal zone and careful control of the growth parameters allowed fabrication of these crystals of reasonable quality. Based on the results of measurements of emission spectra under α-ray excitation and pulse height spectra under α-ray and γ-ray excitations, scintillation characteristics of above crystals including emission wavelength and light yields under α-ray and γ-ray excitations were examined. Additionally, decay kinetics of these materials under α-ray excitation were evaluated.     

Microfluorescence analysis of nanostructuring inhomogeneity in optical fibers with embedded gallium oxide nanocrystals

A spectroscopic protocol is proposed to implement confocal microfluorescence imaging to the analysis of microinhomogeneity in the nanocrystallization of the core of fibers belonging to a new kind of broadband fiber amplifier based on glass with embedded nanocrystals. Nanocrystallization, crucial for achieving an adequate light emission efficiency of transition metal ions in these materials, has to be as homogeneous as possible in the fiber to assure optical amplification. This requirement calls for a sensitive method for monitoring nanostructuring in oxide glasses. Here we show that mapping microfluorescence excited at 633 nm by a He-Ne laser may give a useful tool in this regard, thanks to quasi-resonant excitation of coordination defects typical of germanosilicate materials, such as nonbridging oxygens and charged Ge-O-Ge sites, whose fluorescence are shown to undergo spectral modifications when nanocrystals form into the glass. The method has been positively checked on prototypes of optical fibers--preventively characterized by means of scanning electron microscopy and energy dispersive spectroscopy--fabricated from preforms of Ni-doped Li?O-Na?O-Sb?O?-Ga?O?-GeO?-SiO? glass in silica cladding and subjected to heat treatment to activate gallium oxide nanocrystal growth. The method indeed enables not only the mapping of the crystallization degree but also the identification of drawing-induced defects in the fiber cladding.     

From BACE1 inhibitor to multifunctionality of tryptoline and tryptamine triazole derivatives for Alzheimer's disease

Efforts to discover new drugs for Alzheimer's disease emphasizing multiple targets was conducted seeking to inhibit amyloid oligomer formation and to prevent radical formation. The tryptoline and tryptamine cores of BACE1 inhibitors previously identified by virtual screening were modified in silico for additional modes of action. These core structures were readily linked to different side chains using 1,2,3-triazole rings as bridges by copper catalyzed azide-alkyne cycloaddition reactions. Three compounds among the sixteen designed compounds exerted multifunctional activities including β-secretase inhibitory action, anti-amyloid aggregation, metal chelating and antioxidant effects at micromolar levels. The neuroprotective effects of the multifunctional compounds 6h, 12c and 12h on Aβ???? induced neuronal cell death at 1 μM were significantly greater than those of the potent single target compound, BACE1 inhibitor IV and were comparable to curcumin. The observed synergistic effect resulting from the reduction of the Aβ???? neurotoxicity cascade substantiates the validity of our multifunctional strategy in drug discovery for Alzheimer's disease.     

Regioselective synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles

An efficient and simple method for the synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles has been developed. It consists in the condensation of α-diketone monooximes with aromatic amines and formaldehyde on the presence of boron trifluoride etherate, leading to the formation of stable boron trifluoride complexes of N-oxides. Further reduction of these complexes led to the corresponding imidazoles. This method permits broad variations of substituents in the aryl part of these compounds.     

A new synthesis of 4′-trifluoromethyl-2,2′:6′,2″-terpyridine

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Pericyclic reactions in the synthesis of new 5-aryl-5,6-dihydroquinolino[2,1-b]quinazolin-12-ones

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Solutions of the generalized Dirichlet problem for the iterated slice Dirac equation

Applying the method of normalized systems of functions we construct solutions of the generalized Dirichlet problem for the iterated slice Dirac operator in Clifford analysis. This problem is a natural generalization of the Dirichlet problem.