Some aspects of enhancement of accuracy in results of indirect measurements

Translated from Izmeritel'naya Tekhnika, No. 3, pp. 3–5, March, 1992.     

Phosphorus-enriched hemodialysis during pregnancy: Two case reports

Successful pregnancy leading to delivery of a viable infant is an uncommon occurrence either in women with established renal disease or in those with renal failure requiring chronic dialytic treatment. The frequency of conception in patients with renal failure has increased, however, and the outcome of such pregnancies has improved over the past 32 years. Current guidelines for dialysis in pregnant women include prolonged dialysis times, generally 20 or more hours per week. This extensive dialysis regimen often results in a decrease in the serum inorganic phosphorus levels, with possible detrimental effects to the health of the mother and the unborn child. In this article, we report the successful multidisciplinary management of two pregnant women with end-stage renal disease, both of whom developed hypophosphatemia after initiation of intensive hemodialysis. Sodium phosphate salts were added to the dialysate of each patient and this addition successfully corrected the decrease in serum inorganic phosphate concentration. One patient was able to carry the pregnancy for 28 weeks with delivery of a healthy 1260-g infant. The pregnancy of the second patient ended at 25 weeks of gestation with delivery of a nonviable infant.     

Topological complexity and the dynamics of coarsening

Coarsening or Ostwald ripening occurs in a vast array of two-phase systems. Coarsening results in a decrease in the interfacial area per unit volume and a concomitant increase in the size scale of the interfacial morphology. Much is known about the coarsening process in two-phase mixtures consisting of a polydisperse array of spherical particles. In contrast, in many two-phase mixtures, such as those found in two-phase polymers, ceramics, dendritic solid-liquid mixtures and order-disorder transformations, the interfaces are both interconnected and have a spatially varying mean curvature. Here we show that the morphological evolution of these topologically complex systems during coarsening can be quantified by measuring the probability of finding a patch of interface with a given curvature tensor. We find that the morphological evolution is described by the flow of probability density in this curvature space that is induced by the coarsening process. The hallmark of our approach is a close coupling between experiment and theory; we use the experimentally measured three-dimensional microstructure as an input to a phase-field calculation that then determines the flow in curvature space. The methodology is general, and applicable to many systems undergoing coarsening, regardless of their topology.     

Formation of amorphous powders of alloys of the Cu—Ti system with mechanical activation of powder mixtures

The active mechanical treatment (AMT) of powder mixtures of the Cu−Ti system in a high-power mill and in a medium-power vibrating ball mill in argon allows one to synthesise the phases and to obtain the powders in an amorphous (by X-ray measurements) state. AMT of mixture proceeds via the following stages: grinding of precursor powders, formation of a layered structure, interdiffusion (mass transfer), and attainment of an amorphous state. Zaporozh'e State Technical University. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(402), pp. 118–121. July–August, 1998.     

An electrochemical study of zinc-containing epoxy coatings on mild steel

A comparative electrochemical study has been carried out between conventional zinc-rich and novel zinc-containing paints. To study the cathodic protection performance of these coatings an assessment method based on a galvanic couple was employed. Current and potential were monitored with immersion time in 3.5% NaCl. The zinc-rich paint offered cathodic protection for about 7 days compared with 40 days for the new paint. However, the steel coupled with the zinc-rich remained corrosion free for a further period. This was probably due to the inhibitive effect of zinc salts deposited at the cathode. Thereafter a reversal in polarity was obtained once rust formed. Thus it is concluded that established cathodic protection criteria cannot be solely used to assess the protection properties of zinc-containing paints. Electrochemical impedance spectroscopy was also used to study the state of the coating with time. Diffusion parameters indicated that the new paints were covered with a lesser amount of corrosion products.     

In-Situ X-ray Diffraction Analysis of Metastable Austenite Containing Steels Under Mechanical Loading at a Wide Strain Rate Range

Metallurgical and Materials Transactions A - This paper presents and discusses the methodology and technical aspects of mechanical tests carried out at a wide strain rate range with simultaneous...