Asymmetry of formation of π+-mesons by linearly polarized photons in the region of the first pion-nucleon resonance

This article presents measurements of the asymmetry of formation of ⁺ mesons on a proton by linearly polarized photons in the energy region from 220 to 320 MeV and for pion emission angles 90–135° in the c.m.s. Aphenomenological analysis is carried out on the basis of 25 measured values of the asymmetry and the data of other laboratories. As a result of the analysis, five independent values are obtained for the multipole amplitude functions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 94–101, May, 1978.     

Optical “memory” centers on an adsorption silicon surface

The charging of an illuminated silicon surface discovered by Abkevich [1] is of considerable interest for a number of practical applications (for example, semiconductor photography [2] and gas analysis). The present paper gives the results of investigations aimed at establishing the possibility of controlling the optical charge memory on the silicon surface by adsorption methods.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 92–96, January, 1981.We thank V. F. Kiselev for discussing the work and for helpful comments.     

Photoinjection phenomena in a silicon-silcon dioxide system

Silicon-silicon dioxide structures obtained by thermal, anodic, and chemical oxidation of silicon are studied by the photocharge and photoinjection current methods. It is shown that the extent of the fluctuation state tails" near the edges of the SiO₂ forbidden zone is small (0.2 eV). The threshold for negative photocharging of anodic oxide traps is found to decrease with increase in oxide thickness, a fact related to the existence of a nonstoichiometric transition layer between the silicon and silicon dioxide. The effect of hydration and dehydration on negative optical charge of oxide traps is studied, and it is shown that the basis of electron traps is formed by the most hydrated and deformed SiO₄H_n tetrahedra. The possibility of creating electron and hole traps in the oxide layer by doping with metal ions from a solution is demonstrated. It is found that the corresponding defects are also adsorption centers for water molecules by a coordination mechanism.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 3–7, July, 1981.In conclusion, the authors thank V. F. Kiselev for his interest in the study and valuable remarks.     

Graph Methodology and Principles of Linear Nonequilibrium Thermodynamics in the Theory of Flow-Injection Analysis

It is shown that chemical, configurational, and informational properties of flow-injection systems can be interrelated with the use of the methodology of the graph theory. The main equation of the theory is derived using a mathematical expression of the transition paths from the analyte to the detection of a product of the analytical reaction. Examples of specific developments are discussed for redox reactions, ligand exchange reactions, and heterogeneous exchange reactions, with due regard to, the hidden peculiarities of their chemical mechanisms that are essential for flow analysis and also for on-line preconcentration by coprecipitation. It is also shown that the conditions obtained in a flow system correspond to the basic postulates of linear nonequilibrium thermodynamics, which provides a basis for a new approach to the theory of flow analysis. An example of a complexation reaction was used for discussing the possibility that a linear interrelation exists between flows and forces in a flow system, which corresponds to the Onsager reciprocal relation.     

2-Benzopyrylium salts. 27. Some transformations of 6-oxodibenzo[a,g]-quinolizinium salts

The synthesis of 6-oxodibenzo[a,g]quinolizinium perchlorate — an analog of the alkaloid berberine — and a number of its derivatives, including mesoionic compounds, was accomplished on the basis of a 1-unsubstituted 3-(2-methylenecarboxyaryl)-2-benzopyrylium salt. The interconversions of the compounds obtained in this research were studied.See [1] for communication 26.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1381–1387, October, 1982.     

On the mechanism of vanillin formation in the catalytic oxidation of lignin with oxygen

The influence of catalyst (CuSO₄ solution), pH and temperature on the vanillin formation and oxygen consumption in oxidation of lignin in alkaline media have been studied. It was shown that the main role of catalyst in the lignin oxidation is to change the selectivity of hydroperoxide fragmentation rather than to accelerate oxidation.     

Temperature dependence of nqr spectra in MSbBrF3 (M=Na,Cs, NH4) and Cs3Sb2Br9

Conclusions We have studied the temperature dependence of the NQR parameters of¹²³Sb and⁸¹Br in the range 77–360 K for the complexes of MSbBrF₃ (M=Na, Cs, NH₄) and Cs₃Sb₂Br₉. We have established the temperature regions for which piezoelectric properties appear in the crystal hydrate NaSbBrF₃.H₂O, and in the compounds MSbBrF₃ (M=Na, NH₄) and Cs₃Sb₂Br₉ anomalous changes appear in the dependences of the quadrupole coupling constant, the asymmetry parameter of the electric field gradient for the antimony atoms and the resonance frequency of the bromine atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1501–1504, July, 1987.     

Synthesis and photoinitiated radical cyclization of allyl- and propynyloxymethyl substituted cyclopentanones to tetrahydrocyclopenta[c]furanols

Bicyclic cyclopentafuranols were formed by photoinitiated radical cyclization of allyl- and propinyloxymethyl substituted cyclopentanones with high regioselectivity. The irradiations were carried out at a wavelength of 300 nm in aprotic solvents such as benzene and acetonitrile. We could also show that reductive photoinduced electron transfer (PET) of the propynyloxymethyl substituted cyclopentanone 5 does not lead to any cyclization. The starting materials were synthesized in good yields following known procedures.     

Dissociative ionization of substituted piperideines

The fragmentation of different alkyl(aryl) substituted piperideines [tetrahydro-pyridines] was studied by analyzing high-resolution mass spectra and DADI [Direct Analysis of Daughter Ions] spectra. It was shown that the retrodiene decomposition of the ring is suppressed by competing processes of elimination of ring substitutents. The nature of the substituents and their mutual disposition on the ring have a substantial influence on the extent of their cleavage from the ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 795–800, June, 1988.