Sensitization of Luminescence of Europium Compounds on Solid Matrices by Terbium (III) Ions

The conditions of sensitization of the luminescence of Eu(III) by Tb(III) ions in complexes with inorganic (Na₂WO₄) and organic (nalidixic acid) ligands in sorbates on solid matrices (zeolite CaX and crystalline zirconium phosphate (ZrP)) and in coprecipitation with CaWO₄ have been investigated. It has been established that the maximum sensitization of the europium luminescence is attained in the case where Eu and Tb are present in a 1:0.5 ratio. In this case, the integral intensity of luminescence of Eu(III) (the band with _max = 612 nm) in the sorbate of its complex with nalidixic acid on ZrP accounts for more than 60% of the luminescence intensity of the industrial photoluminophor Y₂O₃:Eu (FL-612) possessing red luminescence, and the intensity of Tb(III) luminescence (the band with _max = 545 nm) accounts for about 40% of the luminescence intensity of the photoluminophor Gd₂O₂S:Tb possessing green luminescence.     

Unsteady gravity-elastic and gravity-capillary ship waves

The development of three-dimensional waves generated by a region of pressures moving uniformly and rectilinearly over the surface of a thin elastic isotropic plate covering an ideal fluid layer of finite depth is investigated. The pressures act starting at a certain instant. A qualitative similarity between the waves occurring and gravity-capillary waves is noted. The calculations are made for an ice cover. This model problem permits examining a number of properties of the oscillations of the ice cover occurring when hauling freight over ice roads, landing and takeoff of aircraft from ice fields, etc. [1]. The development of ship waves in a fluid of finite depth in the absence of a floating plate was investigated in [2, 3] and gravity-capillary waves were studied in [4–6]. Certain properties of steady three-dimensional waves occurring during movement of a load over the surface of a floating elastic plate were established in [1].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 26–32, September–October, 1978.     

Synthesis and Cyclizations of N-(Thieno[2,3-b]pyridin-3-yl)cyanoacetamides

Russian Journal of General Chemistry - 3-Aminothieno[2,3-b]pyridine-2-carboxylic acid esters readily reacted with 3,5-dimethyl-1-(cyanoacetyl)-1H-pyrazole to give previously unknown...     

The Radziszewski oxidation of cycloalkylidene‐α‐(thiazol‐ 2‐yl)acetonitriles: A new approach toward spirooxiranes

Upon treatment with H₂O₂/KOH in EtOH or with Na₂CO₃/H₂O₂ in acetone, cycloalkylidene‐α‐(4‐arylthiazol‐2‐yl)acetonitriles afforded 2‐(4‐arylthiazol‐2‐yl)‐1‐oxaspiro[2.5]octane‐2‐carboxamides and 2‐(4‐arylthiazol‐2‐yl)‐1‐oxaspiro[2.4]heptane‐2‐carboxamides in excellent yields (76–100%). J. Heterocyclic Chem., 2011.     

Cyanothioacetamide in the synthesis of spiro-fused hydrogenated quinolinethiones

The reaction of cyanothioacetamide with a twofold molar excess of 1-(4-morpholino)cyclohexene in dry dioxane afforded previously unknown 3-cyano-4-cyclohexanespiro-1,2,3,4,5,6,7,8-octahydroquinoline-2-thione. Its structure was established by X-ray diffraction analysis and IR and ¹H NMR spectroscopy.     

Surface wave generation in the process of finite deformation of the bottom of a basin

The process of generation of three-dimensional irrotational fluid motions induced by small local finite-duration displacements of part of the bottom of a basin is considered within the framework of wave linear theory for a basin of constant depth. The solution of the problem and an expression for the total wave field energy are obtained using integral transforms. The general properties of the process of unsteady wave generation induced by short-term and slow deformations of the bottom are analyzed. Within the framework of the piston generation model the energy characteristics of axisymmetric waves are compared for two time laws of bottom deformation of identical duration. In general, it is shown that under certain conditions the nature and intensity of the wave process depend on both the time law and the duration of the deformation process.Sevastopol. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 151–156, March–April, 1996.     

Luminescence of europium and ytterbium ions in strontium hexaborate

We have studied the luminescent properties of Eu^2+/3+ and Yb²⁺ ions in strontium hexaborate SrB₆O₁₀ for excitation in the 120–400 nm region. The luminescence spectra of Ln²⁺ ions in SrB₆O₁₀ consist of overlapping bands in the 370–520 nm region, due to 5d → 4f transitions at several nonequivalent centers. In the excitation spectra, besides the bands associated with 4f → 5d transitions in the Ln²⁺ ions, we also observe a band in the 135–160 nm region due to the transitions O(2p) → B(2s,2p) within the borate anions. The luminescence of the Eu³⁺ ions is excited most efficiently in the region of the Eu³⁺ charge transfer band (λ_max = 226 nm). The results obtained are compared with data for Ln in other strontium borates. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 770–774, November–December, 2006.