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Replacing of conventional technology for producing microfilters with a laser technology is presented in the paper. Two approaches for laser drilling through melting and sublimation are discussed. The paper describes possibilities of laser technology in obtaining filters and sieves with different diameters of the holes in the microwave range as well as high homogenity of structures. Detailed analysis of photo-etching as an alternative to laser drilling of microfilters with a certain geometry has been carried out. Advantages and disadvantages of the most common technologies are shown, too
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A lab exercise has been developed to teach students how to monitor and analyze basic characteristics of a photovoltaic (PV) panel. The exercise configuration is based on an electronic unit, previously constructed and reported by the authors. It is applied to measure and record the PV panel voltage at different current loads. Then the Volt-Ampere (V-I) and the output (P-V) characteristics of a PV panel are analyzed. The procedures are done for different light sources and different filters. The analysis and the visualization is executed by a software, developed previously by the authors.
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The influence of mixing procedure on the size of polyelectrolyte complexes (PECs) was investigated using modified jet mixing complexation technique. Two natural weak polyelectrolytes – chitosan and alginate were used for PECs formation. All the experiments were done with 0.1% solution of the polyelectrolytes in acetate buffer with pH 5 and ionic strengths 0.1 M. The average particle diameter was determined by the method of dynamic light scattering using the Microtrac Nanotrac Wave Particle Size, Zeta Potential and Molecular Weight Analyzer. It has been found that decreasing the diameter of the outlet tube, which brings PEC out from the mixing chamber, and increasing its length, reduces the average diameter of the complex that is in the nano-size range. Mixing at a higher pressure in the chamber, which depends on the open state of the jets at the same tube geometry, also results in the formation of smaller PECs. Possible explanation for the observed phenomenon could be the tendency of PEC to aggregate at lower velocities and longer mixing times
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The aim of this paper is to present the nature of the processes osmosis and diffusion, their crucial part in the excretory system of the living organism as well as the physical principles behind dialysis. There are two methods of dialysis - hemodialysis and peritoneal dialysis.
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The sixth issue of SILC “Viewpoints and perspectives in FLT” is comprised of seven papers, which reflect a wide variety of issues in the field of second language acquisition and teacher development and certification. It also offers a book review of a recent publication in the field of contemporary education.
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Improving the status of the teaching profession is seen as an important prerequisite for increasing its appeal for both practicing teachers and university graduates who have obtained a teaching qualification. This state-of-the-art review looks into recent research in the field of creating and maintaining teacher identity and a sense of belonging to the profession of teaching in general, and foreign language teaching in particular. It provides a commentary on a number of issues related to the role of identity in conceptualising professionalism in the field of language teaching. Current research views teacher identity as a multifaceted, dynamic, and context-bound phenomenon, which is closely related to defining and negotiating one's self, and managing the affective domain. Different interpretations of professionalism are discussed, starting from the externally imposed form, sponsored and delineated by policy-makers, to its independent variety, stemming from individual teachers’ views and reflections on their own beliefs and actions. Sponsored professionalism is linked to the recent call for measurable accountability in education worldwide and in Bulgarian higher education.
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