Investigation of radiation swelling in the zirconium-hydrogen system

Conclusions The radiation swelling of the hydrides ZrH_1.78–ZrH_1.90 at a temperature of 50°C is due to the accumulation of zirconium vacancies and their fine pile-ups. At 430–560°C, swelling is determined by the accumulation of fine (10Å) vacancy complexes. In this case, micropores are also formed, with a diameter of 50 Å, but their total volume does not exceed one-tenth of the macroswelling.The considerable buildup of vacancies in the hydrides studied is related with the substructure of the hydride, formed by dislocation voids and the boundaries of twins, which promote an increase of concentration and dispersivity of the injection sinks or themselves serve as these sinks. In samples of the hydride obtained by dehydrogenation of the phase, the numerous dislocations remaining in the hydride after decay of the -phase substructure obviously fulfill this function. The weak tendency of the zirconium vacancies in the hydride to amalgamation in the pores during increased irradiation temperature (by comparison with the behavior of vacancies in metals) is explained by the reduction of their surface energy as a result of interaction with hydrogen atoms.The displacement of hydrogen atoms from the tetrahedral positions during irradiation and their return during annealing changes the periods of the crystal lattice of zirconium hydride in the same way as the change of hydrogen content, which enables the number of defects of the hydrogen sublattice to be estimated.Translated from Atomnaya Énergiya, Vol. 42, No. 1, pp. 16–19, January, 1977.     

A new self-expanding lined stent-graft in the dog ureter: radiological, gross, histopathological and scanning electron microscopic findings

Recurrent or intractable ureteral strictures pose a significant problem for the practicing urologist. Metallic stents have been used sparingly for this problem with varying success. We investigated the use of a stent-graft consisting of a metal stent lined with a porous biocompatible polymer to determine if the liner would prevent urothelial ingrowth. One ureter of each of 11 dogs was treated with either a metallic woven stent or stent-graft inserted retrograde via a midline cystotomy. Six bare wire stents (controls) and five lined with a new, porous, biocompatible, polycarbonate elastomer liner (Corethane) were placed. The animals were followed radiographically with intravenous urography (IVP) at 6 weeks and just prior to sacrifice (12 to 22 weeks). Gross, histological, and electron microscopic analyses were performed. The results demonstrate that all of the bare metal stented animals developed moderate to severe hydroureteronephrosis with significant urothelial hyperplasia and ingrowth through the spaces between the metal wires. The animals implanted with lined stents showed one instance of mild hydroureteronephrosis (observed radiographically but not grossly at time of sacrifice) and virtually no papillary in-growths of urothelium through the stent interstices. This obstructive phenomenon was prevented by the porous polymer lining. There was no evidence of biodegradation of the liner on scanning electron microscopy. Based upon these findings, the marriage of a biocompatible polymer which provokes minimal tissue reaction, and metallic stents which provide tremendous strength, seems to offer significant advantages when placed into the urinary tract to maintain ureteral luminal patency.     

Characteristics of micromethods for the analysis of the in vitro synthesis of antibodies against xenogenic erythrocytes

In order to choose an optimal assay for screening cell microcultures containing anti-xenogenic erythrocyte antibodies in their supernatants, two microassays were compared: microhemagglutination and hemolytic patch assay. Samples of murine sera, each in both assays, were examined for the antibody titer. It is shown that the sensitivity of the assays is approximately at the same level, as the statistically significant difference in the amount of antibodies evaluated either by hemagglutination or by patch assay was not found. Hence one should not prefer any of the assays from the standpoint of sensitivity, when choosing the screening procedure for hybridomas of lymphoid cell microcultures secreting antibodies against xenogenic red blood cells.     

Radiation-induced swelling of zirconium hydride

Physics and Energy Institute (FÉI), Obninsk. Translated from Atomnaya Énergiya, Vol. 71, No. 2, 178–180, August, 1991.     

The application of lumbar sympathectomy in complex of treatment of obliterating atherosclerosis

The lumbar sympathectomy was conducted for the grade II (according to Fontaine) obliterating atherosclerosis of the lower extremities arteries in 309 cases as the main method of surgery, and in 426--in concurrence with reconstructive intervention on the main vessels. The indications for and the efficacy of the desympathization in various levels of the main arterial bed affection are discussed.