Decorative metallic coatings applied with galvanic method

In the presented paper the authors aimed at describing the effects of basic parameters of galvanizing process upon the quality of the obtained silver decorative coatings

Microstructure and Degree of Degradation of ZnO Varistors in Surge Arresters Due to Operation

The paper presents the test results for the microstructure of ZnO varistors comprising high voltage gapless surge arresters. The tests were performed on varistors produced in different periods and by various manufacturers. The research was inspired by different characteristics of changes in values of current flowing through surge arresters as a function of changes in values of system voltage in a 220 kV substation, and the temperature in a multi-year cycle. Furthermore, the effects of varistor microstructure degradation following a failure of an unsealed surge arrester were investigated. The results provided the grounds for assessment of ZnO varistor microstructure parameters in terms of their durability and resistance to degradation processes

Investigation of Microstructure of ZnO Varistors Taken From Surge Arrester Counters

The paper presents investigations of microstructure of varistors of damaged surge arrester counters. A similar ZnO varistor, not subjected before to operation, was a point of reference in this research. The results of investigations of the ZnO varistors show an untypical phase composition of their material, which was characterized by unsatisfying homogeneity and cohesion. The degradation processes of varistor material in the subsequent stages were recognized and described. A harmful impact of humidity inside the untight surge arrester counter on its operation and its ZnO varistors was proved. Some conclusions being the result of the operation checking of surge arrester counters were presented too

Decorative metallic coatings applied with galvanic method

In the presented paper the authors aimed at describing the effects of basic parameters of galvanizing process upon the quality of the obtained silver decorative coatings

Study of Composite Insulator Sheds Subjected to Wheel Test

The paper presents investigation of the properties of the surface and the material stiffness – flexibility of series of samples taken from the sheds of the composite insulators. The insulators were previously subjected to wheel test. The wheel test and 1000 h salt fog test are regarded as alternative examination of the material resistance to the effects of electrical surface discharges. There were investigated two series of the samples of the composite insulators sheds. Examined specimens, made of HTV silicone rubber, were taken from the sheds of medium-voltage composite insulators of two different manufacturers. Insulators of both types passed the 1000 h salt fog test without reservation. Meanwhile, the wheel test can provide a basis for better distinguishing between physical properties of the tested materials. In the case of the insulators of one of the manufacturers the wheel test result was negative. Cross puncture effect of the sheds took place in several places. In addition, sheds were covered with dark coating of varying thicknesses. The results of the study indicated a significantly stronger influence of electrical and temperature factors on the sheds under investigations during the wheel test than in the case of the 1000 h salt fog test. It can be stated that these tests cannot be considered as alternative and it seems that wheel test enables better distinguishing between properties of the materials

Comparative Studies on Degradation of Varistors Subjected to Operation in Surge Arresters and Surge Arrester Counters

The paper presents results of investigation of microstructure and micro-hardness for material of ZnO varistors applied to 110 kV surge arrester and surge arrester counter. The research combined two pairs of varistors, each consisted of one varistor subjected before to operation, while the other one was brand new unit and constituted a reference. All varistors were made of the same material by the reputable manufacture. The tests revealed a different degree of the material degradation for varistors subjected before to operation. This also refers to different degradation mechanism observed for the material of these varistors, if typical effects of degradation of aged ZnO varistors were considered as a reference. Physical state of spinel in the microstructure had a significant impact on the material degradation, however a considerable loosening of the microstructure associated with bismuth oxide was observed too. It was surprising, since the precipitates of the bismuth oxide phase most often showed very good binding to the ZnO matrix and high resistance to associated electrical, thermal and mechanical effects. The degradation effects in the ZnO matrix proved to be limited only

Immunopolarization of CD4(+) and CD8(+) T cells to type-1-like is associated with melanocyte loss in human vitiligo

Vitiligo is an autoimmune condition characterized by loss of epidermal melanocytes. High frequencies of melanocyte-reactive cytotoxic T cells in the peripheral blood of vitiligo patients and the observed correlation between perilesional T-cell infiltration and melanocyte loss in situ suggest the important role of cellular autoimmunity in the pathogenesis of this disease. We isolated T cells from both perilesional and nonlesional skin biopsies obtained from five vitiligo patients, then cloned and analyzed their profile of cytokine production after short-term, nonspecific expansion in vitro. Perilesional T-cell clones (TCC) derived from patients with vitiligo exhibited a predominant Type-l-like cytokine secretion profile, whereas the degree of Type-1 polarization in uninvolved skin-derived TCC correlated with the process of microscopically observed melanocyte destruction in situ. Detailed analysis of broad spectrum of cytokines produced by perilesional- and nonlesional-derived CD4(+) and CD8(+) TCC confirmed polarization toward Type-1-like in both CD4 and CD8 compartments, which paralleled depigmentation process observed locally in the skin. Furthermore, CD8+ TCC derived from two patients also were analyzed for reactivity against autologous melanocytes. The antimelanocyte cytotoxic reactivity was observed among CD8(+) TCC isolated from perilesional biopsies of two patients with vitiligo. Finally, in two of five patients, tetramer analysis revealed presence of high frequencies of Mart-1-specific CD8 T cells in T-cell lines derived from perilesional skin. Altogether our data support the role of cellular mechanisms playing a significant part in the destruction of melanocytes; in human autoimmune vitilig

The Sarmatian Review, Vol. 19, No. 3

Contents: "SR INDEX"; "Jerzy Giedroyc-Melchior Wańkowicz Correspondence", edited by Aleksandra Ziółkowska-Boehm"; "BOOKS and Periodicals Received"; "Andrzej Walicki on Ideas in Russia" edited by Andrzej de Lazari (review); Marek Chodakiewicz, "Poland and the Future of NATO"; Richard J. Hunter, Jr., and Leo V. Ryan, C.S.V., "Prospects for the Polish Economy, 1999-2000"; Sally Boss, "Afterthoughts on Wisława Szymborska"; "LETTERS" "ANNOUNCEMENTS AND NOTES"; "About the Authors