INFLUENCE OF WELDING TECHNIQUES ON MICROSTRUCTURE AND HARDNESS OF STEEL JOINTS USED IN AUTOMOTIVE AIR CONDITIONERS

Austenitic steels belong to a group of special-purpose steels that are widely used in highly aggressive environments due to their enhanced anticorrosive behavior and high mechanical properties. The good formability and weldability of these materials has made them very popular in automotive AC systems. This study presents the results of hardness tests and microstructure observations on plasma- and laser-welded joints. The examined joints consisted of two different stainless steel components; i.e., a nipple made from corrosion-resistant AISI 304 steel and a corrugated hose made from 316L steel. Microplasma welding was carried out on a workstation equipped with an MSP-51 plasma supply system and a BY-100T positioner. The laser-welded joint was made on a numerically controlled workstation equipped with an Nd:YAG laser (without filler material) with 1 kW of maximum power; the rotational speed of the welded component was n = 4 rpm. Microstructural observations were performed using a scanning electron microscope and an optical microscope. Vickers hardness was measured with a hardness tester. The obtained results proved that both the microplasma- and laser-welded joints were free from any visible welding imperfections. In the micro areas of the austenitic steel weld, crystals of intercellular ferrite appeared against a background of austenite. The crystallization front (depending on the welding technology) was running from the fusion line towards the weld axis. The grain size depended on the distance from the fusion line

Spatial Relations between the Theatre and Its Surroundings: An Assessment Protocol on the Example of Warsaw (Poland)

Theater as a place, but also as a field of human and team activity involving the creation of performances performed in the presence of the viewer, has a centuries-old history. This study aims at examining the links between theatre architecture/space and public spaces, trying to answer to what extent these objects have become attractors in its space and how they affect the activity of cultural and social life. The subjects of the study are Warsaw theatres, both historical and contemporary, in the context of their impact on the surrounding public spaces. A specific methodology was elaborated to evaluate potential impacts. According to the spatial relations between the theatre and its surroundings, they are clustered in the following typologies: emanation, isolation, and interference theatre. The research methods applied for defining and solving the scientific problem are: (i) critical analysis, (ii) comparative analysis, (iii) observation without intervention, and (iv) intuitive method based on the author’s personal experience. The conclusions are based on empirical research, with particular emphasis on the research material obtained by field research. The results of the research allow one to draw conclusions regarding the influence of theatrical places on public spaces in the city structure. The mission of the theater is changed, activating events and building social bonds. Theater space and its surroundings are shaped in accordance with these new standards and social expectations to be transformed into a public space of a cultural nature. Thus, presently, urban theatrical space is a site for spectacle, with a social and cultural mission. Theater space and its surroundings should be shaped in accordance with changing standards and social expectations, and it should be a public space of a cultural nature

Analysis of the G/C polymorphism in the 5'-untranslated region of the RAD51 gene in breast cancer.

The breast cancer suppressor proteins BRCA1 and BRCA2 interact with RAD51, a protein essential for maintaining genomic stability by playing a central role in homology-dependent recombinational repair of the DNA double-strand breaks. Therefore, genetic variability in the RAD51 gene may contribute to the appearance and/or progression of breast cancer. A single nucleotide polymorphism in the 5'- untranslated region of RAD51 (a G to C substitution at position 135, the G/C polymorphism) is reported to modulate breast cancer risk. We investigated the distribution of genotypes and frequency of alleles of the G/C polymorphism in breast cancer. Tumor tissues were obtained from postmenopausal women with node-negative and node-positive breast carcinoma with uniform tumor size. Blood samples from age matched healthy women served as control. The G/C polymorphism was determined by PCR-based MvaI restriction fragment length polymorphism. The distribution of the genotypes of the G/C polymorphism did not differ significantly (P >0.05) from those predicted by the Hardy-Weinberg distribution. There were no differences in the genotype distribution and allele frequencies between node-positive and node-negative patients. There were no significant differences between distributions of the genotypes in subgroups assigned to histological grades according to Scarf-Bloom-Richardson criteria and the distribution predicted by Hardy-Weinberg equilibrium (P >0.05). Our study implies that the G/C polymorphism of the RAD51 gene may not be directly involved in the development and/or progression of breast cancer and so it may not be useful as an independent marker in this disease