Determination of fibrin and fibrinogen split products by their anticoagulant activity

A new diagnostic method to determine fibrinogen and fibrin splitting products is based on the fact that high-molecular fragments acting as specific inhibitors of fibrin self-assembly compose these products. Fibrinogen and fibrin splitting products are detected and determined quantitatively by prolongation of coagulation time in the test with the standard monomeric fibrin. The number of units of anticoagulating activity in the studied urine are the results of the determinations. Sensitivity of the method if necessary may be increased by adding of a certain amount of the fibrinogen and fibrin splitting products to the test that makes a favourable background for the action of the products. The method is rather sensitive, reliable and simple. It may be used in ordinary clinical laboratories. The method proved to be quite satisfactory when testing renal diseases at the clinic. It is of great significance for early detection of the transplanted kidney rejection. The new method is compared with the known immunological method which consist in determination of the inhibitory effect of the fibrinogen and fibrin splitting products on agglutination of erythrocytes of specific antibodies; the erythrocytes being subjected to "tanning" and "loading" with fibrinogen. A satisfactory correlation is found between the results of two methods.     

Non-alloy Cr/Au Ohmic contacts in the technology of planar beam-lead GaAs <Emphasis Type="Italic">p-i-n</Emphasis> diodes

The characteristics of non-alloy Cr/Au ohmic contacts in planar beam-lead GaAs p-i-n diodes have been studied. The room-temperature reduced contact resistance in the structures studied was 2 × 10⁻⁶ Ω cm². The obtained parameters of p-i-n diodes allow these devices to be used as limiters in radar protection systems.     

Denitration of Nitric Acid Raffinates with Urea

Urea denitration, i.e., precipitation of HNO₃ from simulated nitric acid raffinates of uranium works with urea, is studied, including factors influencing the process performance, particularly distribution of uranium and other admixtures between the liquid phase and precipitate. In denitration of solutions containing free nitric acid and nitrates, only free HNO₃ is precipitated. The method allows reduction of the HNO₃ concentration from 3.5 to 0.5 M in a single stage.     

Asymptotic Stability Conditions and Estimates of Solutions for Nonlinear Multiconnected Time-Delay Systems

This paper examines certain classes of multiconnected (complex) systems with time-varying delay. Delay-independent stability conditions and estimates of the convergence rate of solutions to the origin for those systems are derived. It is shown that the exponents in the obtained estimates depend on the parameters of Lyapunov functions constructed for the corresponding isolated subsystems. The problem of computing parameter values that provide the most precise estimates is investigated. Some examples are presented to demonstrate the effectiveness of the proposed approaches.     

Assessing the efficiency of centrifugal pumps

A method is developed for assessing the efficiency of centrifugal pumps, by optimization of the parameters so as to ensure maximum hydraulic efficiency. Formulas for the other components of the pump??s efficiency are presented.     

Manganese extraction from slag obtained in the production of refined manganese ferroalloys

The extraction of manganese from the tailings slag obtained in the production of refined manganese ferroalloys is studied thermodynamically and experimentally. In such extraction, the slag reacts with metal melts (hot metal, ferromanganese, and ferrosilicomanganese) containing reducing elements (carbon and silicon), with the goal of increasing the overall transfer of manganese to the final manganese ferroalloys. According to the results, the reduction of manganese by carbon only occurs in the case of hot metal. A method is developed for alloying hot metal with manganese from tailings slag obtained in the production of refined manganese ferroalloys.     

Active monitoring systems in the machining of discontinuous surfaces

A machine-tool system for active monitoring by vibrocontact measurement is proposed. This equipment increases the machining precision and productivity and also the technological margin of precision.     

The influence of combustion efficiency on the characteristics of ramjets

Methods for determining the combustion efficiency, thermodynamics parameters of propellants, and characteristics of ramjets are analyzed. Energetic and multizone models taking into account various physical processes of incomplete combustion are considered. An approach based on comparison of the combustion efficiency evaluated by different models is developed, and recommendations on their application are given. The results and mathematical models presented can be used in numerical computational and experimental studies of the working processes in ramjets.