Differential Energy Criterion for Brittle Fracture: Conceptualization and Application to the Analysis of Axial and Lateral Deformation in Uniaxial Compression of Rocks.

This paper discusses modeling the behavior and prediction of fracture of brittle materials. Numerous publications show that progress in this area is characterized by the emergence of a number of new models that meet the requirements of the mining industry, construction and other engineering practices. The authors focus only on one class of models, paying special attention to the compromise between simplicity of solution and versatility of the model.

Energy Criterion for Fracture of Rocks and Rock-like Materials on the Descending Branch of the Load-Displacement Curve.

This article deals with the problem of predicting the brittle fracture of rocks and similar materials, which can also include frozen sandy soils. Such materials, due to the diversity of their conditions of origin, are characterized by natural heterogeneity at the micro-, meso-, and macro-levels, which makes it difficult to develop sufficiently universal criteria for their strength. Despite a number of known models and criteria of strength and fracture, the search for such criteria remains an urgent problem.

Templating irreversible covalent macrocyclization by using anions.

Inorganic anions were used as templates in the reaction between a diamine and an activated diacid to form macrocyclic amides. The reaction conditions were found to perform the macrocyclization sufficiently slow to observe a template effect. A number of analytical methods were used to clarify the reaction mechanisms and to show that the structure of the intermediate plays a decisive role in determining the product distribution.

Macrocyclic receptor for pertechnetate and perrhenate anions.

The design and synthesis of a neutral macrocyclic host that is capable of perrhenate and pertechnetate recognition is described. The anion affinities and underlying coordination modes were estimated by several experimental and theoretical methods including a new technique--reverse (99)Tc NMR titration.

Molecular recognition of pertechnetate and perrhenate.

This tutorial review covers the chemistry of artificial receptors designed to recognize the pertechnetate and perrhenate anions. It focuses on the molecular features that give rise to effective and selective complexation. Specific receptor classes are discussed in the context of available solution-phase and solid-state data with differences between pertechnetate and perrhenate binding behavior being highlighted where appropriate.

[A system for assessing the stability of the osteosynthesis in femoral neck fractures].

Results of experimental investigation of different biomechanical parameters of the system "bone-fixative" and bony fixatives are analyzed in relation to different types of fractures of the femur neck. The data obtained are compared with clinical results of osteosynthesis. On this basis an index system is recommended for choosing the method of treatment of fractures and the particular type of the fixative.

[The characteristics of the electromagnetic situation close to overhead electric power transmission lines in St. Petersburg].

According to task by Environmental Protection Department of St. Petersburg Municipal Administration, levels of electromagnetic fields induced by high-voltage electric power lines were measured in development lands of St. Petersburg.

[The conservative treatment of children with vesico-ureteral reflux].

The article deals with the results of examination and nonoperative treatment of 120 children with vesicoureteral reflux (VUR). Their ages ranged from 3 to 13 years. The authors used a complex of methods for the examination of the functional condition of the kidneys, upper urinary tract (excretory urography, renoscintigraphy, electroureterography, clearance tests), lower urinary tract (cystography, cystoscopy, cystotonometry, urethroprofilometry, electromyography of the detrusor and its obturator apparatus), bacterio- and immunological studies (determination of the microbial number, bacteria covered with antibodies, immunoglobulins G, A, and M).

[Methods of biomonitored electrostimulation of neuromuscular structures and their technical realization].

Up-to-date approach to electrostimulation of neuromuscular structures of the skeletal muscles of man is discussed in the article. The authors analyse informative for bioregulation parameters of the object of electrostimulation. Two variants of realization of biomonitored electrostimulation, with an automated length of exposure and with arbitrary electrostimulation monitoring of motor activity, are described in the article.

[Experience in developing experimental devices for the multichannel electric stimulation of neuromuscular structures].

Multichannel electrostimulators are used for electrostimulation of some groups of muscles. A number of requirements should be borne in mind when designing such devices: the structure of the signals for multichannel electrostimulation must be physiological; the interaction between the channels must be eliminated; the energy of the electrostimulation must be measured; the impedance of the electrode-skin system must be stabilized; a method of electrode electrostimulation, not involving wetting, is to be developed.