New Colloid Silicate Solutions for Restoration and Conservation of Stone Facades

The kinetics of water absorption by samples taken from facades of buildings (marbled footinglimestone, bricks, plaster), both in initial state, those treated with solutions of classical water repellentsand new hydrophilic and hydrophobic colloid silicates, was studied, and the state of the initial materialwas assessed. Recommendations on how to stabilize stone and protect it from the destructive influence of the humid atmosphere are given.     

Cold-electron bolometer arrays

To improve electron cooling, expand the dynamic range, and match the input and output impedances, series/parallel arrays of cold-electron bolometers have been developed, manufactured, and measured at temperatures from 50 to 350 mK. The bolometers are integrated into cross-slot antennas to analyze the polarization of cosmic microwave background radiation at a frequency of 345 GHz. The maximum temperature response is 6.5 μV/mK. The noise-equivalent electric power at a temperature of 300 mK is 1.2 × 10^?17 W/Hz^1/2.     

Submillimeter-wave Josephson spectroscopy

A Josephson high-temperature superconducting (HTSC) submillimeter-wave spectrometer is designed, built, and experimentally investigated. The integrated detection structure of the spectrometer includes a YBCO Josephson junction on a bicrystalline boundary, a double-slot or log-periodic antenna, and a low-inductance resistive shunt. The selective detector response and the response at an intermediate frequency of 1.4 GHz are measured under the action of a signal in the frequency range 350–1250 GHz. Three methods of spectroscopy are investigated using this setup: 1) a method of Hilbert spectroscopy with processing of the detector response is implemented; 2) it is found that for a wide Josephson line at intermediate frequency (IF) the response has the same form as the detector response, making it possible to obtain a spectrum and the width of the generation line from IF response measurements; 3) for a narrow Josephson line the IF response corresponds to the regime of conversion with self-pumping. A new method is proposed for calculating the emission spectrum. The method consists of simple shift, summation, and subtraction operations. The advantages of the method are simplicity, high sensitivity, and high resolution. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 5, 338–343 (10 September 1999)     

Platinum nanoparticles on fullerene black as effective catalysts of hydrogenation

Fixation of platinum from H₂PtC_l6 on fullerene black through non-conjugate double bonds or hydroxyl groups created on their base in the presence of an organic base with postreduction by formate ions allows platinum particles of size 3–4 nm to be obtained. These compositions catalyze 1-decene and nitrobenzene hydrogenation and exceed in activity the traditional catalyst Pt/C with platinum particle size of 70–80 nm. The average size of the fixed platinum particles affects the catalytic activity stronger than the specific surface area and the electron conduction of the carrying agent.     

Boundary-value problem for nonlinear Schrödinger equation

Leningrad State University. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 79, No. 3, pp. 334–346, June, 1989.     

Interaction of 2-chloroquinoline- 3-carbaldehydes with 2-hetaryl- acetonitriles

The interaction of 2-chloroquinoline-3-carbaldehydes with 1H-benzimidazol-2-ylacetonitriles and 1-benzyl-1H-imidazol-2-ylacetonitrile has been studied. It was shown that products of condensation at the methylene group are formed under mild conditions. Carrying out the reaction under more forcing conditions leads to an intramolecular nucleophilic substitution of the chlorine atom and the formation of cyclic ionic compounds (in the case of N-substituted hetarylacetonitriles), which are subsequently dealkylated.