Investigation of the effect of a vertical surcharge on horizontal displacements and resistance of pile columns to horizontal loads

Conclusions 1. The principle of independence of the action of forces in the general case is not applicable to calculation of pile columns with relative embedment < 15. A vertical surcharge can somewhat decrease (in weak saturated soils) or increase (in clays of very stiff consistency) the resistance of pile columns to horizontal loads. In the investigated saturated soils, the bearing capacity decreased by no more than 15%, and in very stiff slump-prone soils it increased by a factor of 1.9.2. Under equal conditions, pile columns with cantilevers absorb a 1.3–1.6 times greater horizontal load than prismatic.3. When designing pile columns, the depth of their conditional embedment in the soil should be determined in conformity with the requirements of Instructions [12] and not by Table 12 in SNiP II-B.5-67*, since this leads to uneconomical reinforcement of the pile columns.4. For pile columns of agricultural buildings a permissible crack width of 0.3 mm should be adopted instead of the 0.2 mm according to SNiP II-B.5-67*.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 11–14, January–February, 1978.     

Electropolymerized flavin adenine dinucleotide as an advanced NADH transducer

Electropolymerizing the prosthetic group (flavin adenine dinucleotide, FAD) responsible in the active sites of dehydrogenases for NAD(+)|NADH regeneration, we succeeded in mimicking enzyme activity. Poly(FAD) characterized by an additional polymer-type redox reaction has been discovered as a highly effective electrocatalyst for NADH oxidation: operating at the lowest potentials reported for NADH transducers (0.00 V, pH 7.4), poly(FAD) is characterized by the electrochemical rate constant of 1.8 +/- 0.6 x 10(-3) cm s(-1), which is at the level of the NADH mass-transfer constant. Flow injection analysis of NADH with the poly(FAD)-modified wall-jet electrode as a detector has been characterized by a linear calibration range prolonged down to 5 x 10(-7) M and a sensitivity of 0.08 A M(-1) cm(-2), which taking into account the dispersion coefficient ( approximately 3), is at the diffusion-limiting value. In contrast to the low molecular weight mediators able to exhibit similar electrocatalytic properties, poly(FAD)-modified electrodes are characterized by the dramatically improved stability and, thus, can be considered as the most advantageous NADH transducers for analytical chemistry.     

Conditions for Instability of One Class of Nonlinear Nonautomomous Dynamic Systems

Consideration was given to the conditions for instability of the equilibrium states of a nonlinear nonautonomous dynamic systems obeying an ordinary vector differential equation of arbitrary order whose right-hand side satisfies the following conditions: (i) for any t 0, div 0$$ " align="middle" border="0"> almost everywhere on the set H that is a neighborhood of the equilibrium point of the system and (ii) at any point . The equilibrium states of such systems can be both stable and unstable. For one class of these systems, sufficient instability conditions were given, which enables one to carry out studies using only the information about the right-hand side of the system.     

Instability Conditions for Nonlinear Nonautonomous Dynamic Systems. II. Sufficient Conditions of Instability

In Part I, using a special class of scalar functions V(x, t, ) dependent on a parameter , we have derived new necessary and sufficient conditions for the instability (in some domain) of the equilibrium states of nonlinear nonautonomous dynamic systems of arbitrary order. In Part II, we derive new sufficient conditions for the instability of a class of unstable systems in terms of functions admitting a simple geometric interpretation.     

Preparation of High-Purity Arsenic via Hydrogen Reduction of Arsenic Trichloride

The chemical equilibria involved in the hydrogen reduction of arsenic trichloride under reaction conditions of practical interest are assessed by thermodynamic modeling. Experimental data for high-purity arsenic trichloride are used to optimize the reduction conditions. The optimal residence time of the gas mixture in the reaction zone is 30–50 s. The optimal reduction temperature is 1023 K. Condensation temperatures in the range 600–650 K make it possible to minimize the percentage of amorphous arsenic. The yield of elemental arsenic is 99.99%.