The article reports the results of integrated assessment of in situ stresses in rock mass in the Nurkazgan Mine. The visual observation of underground excavations and instrumental measurements of effective stresses denote the hydrostatic stress state within the studied minefield.

Exact algebraic algorithms for calculating the product of two elements of nilpotent associative algebras over fields of characteristic zero are considered (this is a particular case of simultaneous calculation of several multinomials). The complexity of an algebra in this computational model is defined as the number of nonscalar multiplications of an optimal algorithm. Lower bounds for the tensor rank of nilpotent associative algebras (in terms of dimensions of certain subalgebras) are obtained, which give lower bounds for the algebraic complexity of this class of algebras. Examples of reaching these estimates for different dimensions of nilpotent algebras are presented.

We obtain the lower bounds for the tensor rank for the class of nilpotent and solvable Lie algebras (in terms of dimensions of certain quotient algebras). These estimates, in turn, give lower bounds for the complexity of algebraic algorithms for this class of algebras. We adduce examples of attainable estimates for nilpotent Lie algebras of various dimensions.

Exact algebraic algorithms for classical simple Lie algebras over fields of characteristic zero are considered. The complexity of an algebra in this computational model is defined as the number of (non-scalar) multiplications of an optimal algorithm (calculating the product of two elements of the algebra). Lower bounds for the algebraic complexity are obtained for algebras in the series , , and . Bibliography: 3 titles.

The problem on possible creation of monitoring system ensuring reliable prediction of catastrophic manifestations of rock pressure is considered. The mathematical model of hierarchical block mass is presented for describing the development of nonlinear consolidation and deconsolidation processes. The analytical methods are proposed for the model investigation to reveal possible origination of catastrophes.

The use of photoresists as mask materials in ion implantation is studied theoretically and experimentally. Recommendations for optimizing mask thickness in the CMOS context are made.

Reaction of nitrogen(I) oxide with nitrogen-fixing systems Li/Me 3 SiCl/MCl n (MCl 4n = CrCl 3 , CoCl 2 , Cp 2 TiCl 2 , FeCl 3 , CuCl 2 ). In these systems nitrogen(I) oxide, molecular nitrogen, and air nitrogen undergo reductive silylation to tris(trimethylsilyl)amine. The efficiency of the process was estimated by the molar ratio of the tris(trimethylsilyl)amine formed to metal chloride MCl n n . The reaction of N 2 O with the nitrogen-fixing systems including CoCl 2 and Cp 2 TiCl 2 is not exhausted by the reduction of the former to molecular nitrogen and its subsequent fixation by transition metal complexes.

The reaction of nitrous oxide with some cyclopentadienyl Compounds of cobalt, rhodium, and titanium was studied. The corresponding furans were obtained in low to moderate yields.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An experiment on the modification of the optical constants of polymethyl-methacrylate and polystyrene films by light-ion bombardment is presented. It is shown that ion implantation is an efficient technique to modify the optical properties of polymers and that the values of their refractive index can be predicted from changes in the molecular refraction.

Generalized information on the results of determining the natural stresses in a rock mass, obtained under conditions of underground mines on the territory of Northern Eurasia, is given in the form proposed by M. L. Zobak for the project of the world-stress map. The quality of experimental data is analysed. In the main mineral resource regions, the features of variation in the stress state of rock mass with increase in depth of mining operations are noted.

The modem lines in the development of the nitrogen(I) oxide chemistry are considered. Data on the structure, physical properties and reactivity are generalised. The effect of N2O on the environment and the possibility of its utilisation are considered. Attention is focused on the processes in which the oxidative potential of nitrogen(I) oxide can be employed.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The diverse information collected during fulfillment of the present study on the Tashtagol deposit as a geomechanical entity on the local level, and also the procedure developed for numerical modeling make it possible to perform a detailed analysis of the geomechanical situation that develops near mining operations and in the adjacent mass. The constructed model is “open” for the introduction of additional information on stress fields, the number, location, and state of faults, and other geomechanical information, and is also easily adapted for solution of dynamic (for example, on blast-induced breaking) problems. Similar models may be constructed for all iron-ore deposits of the Gornoi Shorii.

A nontraditional monitoring procedure, which is based on the use of three-dimensional geomechanical models constructed in accordance with the hierarchical principal, ensures quantitative estimates of the stress-strain state of a mass, which assume practical significance. The algorithm that we have developed reflects the sequence of data preparation for the construction of a model and numerical analysis of stress fields using an original software package developed at the Mining Institute, Siberian Branch of the Russian Academy of Sciences. A different kind (geological, geophysical, and seismological) of data, which directly or indirectly characterize the field of stresses acting in a mass, and the adequate scale of the model is considered in formulating boundary conditions in models.