Influence of carbonate aggregate type on mechanical properties of mortars

Aim of research work was to examine the effect of alkali-aggregate reaction on mechanical properties of mortars. There we prepared samples - mortar prisms. As a binder we used lime, lime with addition of tuff, cement and cement with fly ash. We also used two different types of aggregate, limestone and dolomite. All samples were first cured in adequate environmental conditions. Samples with lime binder were cured in the laboratory conditions for three months. Samples based on cement binder were cured for 28 days in water. After that samples were exposed to accelerated aging conditions, increased temperatures and/or NaOH solution, and reference conditions - deionized water with 20°C. We measured mass and length change in predetermined time intervals up to three months. Compressive\ud and flexural test were carried out in order to determine influence of type of carbonate aggregate on mechanical properties of mortars

Design of the railway line Domžale - Brnik - Kranj

V magistrski nalogi je obravnavana zasnova železniške proge Domžale – Brnik – Kranj z navezavo na obstoječi železniški progi Ljubljana – Kamnik Graben in Ljubljana – Jesenice d.m. V prvem delu naloge predstavimo izhodišča in kratek razvoj omrežja TEN – T v Evropski uniji ter na območju Slovenije. V nadaljevanju opišemo vpeljavo železnice na primestna območja in pomembnost uporabe trajnostne mobilnosti. V drugem delu magistrske naloge opišemo robne pogoje trase, ki so vplivali na izbiro variante in orodja ter podloge, ki smo jih uporabili pri zasnovi železniške proge Domžale – Brnik – Kranj. V tem delu so predstavljene tudi tehnične zahteve, ki so določale izhodišča pri projektiranju železniške proge. Predstavljene so tri različne variante prog in njihova umestitev v prostor. V nadaljevanju drugega dela sta predstavljena vrednotenje in metodologija vrednotenja treh variant ter izbira najprimernejše variante, ki smo jo v nadaljevanju optimizirali. V tretjem delu magistrske naloge so podani tehnični podatki o izbrani varianti z vsemi tehničnimi elementi trase, izračuni progovnih hitrosti s pomočjo programa za izračun potovalnih časov med postajama in izdelanim voznim redom, s katerim smo ocenili razmik med zaporednima vlakoma, ki bi ga omogočala enotirna povezava Ljubljana – Domžale – Brnik – Kranj.This master’s thesis describes the design of the Domžale – Brnik – Kranj railway line with connection to the existing railway line Ljubljana – Kamnik Graben and Ljubljana – Jesenice d.m. In the first part of the thesis, we present the main points and short development of the TEN – T network in the EU and in Slovenia. Further, we describe introduction of the railway to the suburban areas, and importance of sustainable mobility. In the second part of the thesis, we describe the boundary conditions of the route, which influenced the choice of variants and tools and substrates used in the design of the railway line Domžale – Brnik – Kranj. In addition, this section also describes the technical requirements that determine the starting points for the design of the railway line. Three different variants of the railway lines and their placement in the space are presented. Further in the second part, evaluation and evaluation methodology of the three variants and selection of the most suitable variant are presented, which are then optimized. In the third part of the thesis, technical data are given on the selected variant with all the technical elements of the railway route, the calculations of linear speeds using the program for calculating travel times between stations and the timetable, with which we evaluated the frequency of trains, which would be allowed by the monorail connection Ljubljana – Domžale – Brnik – Kranj

Structural insights into photosystem II assembly

International audienceBiogenesis of photosystem II (PSII), nature's water splitting catalyst, is assisted by auxiliary proteins that form transient complexes with PSII components to facilitate stepwise assembly events. Using cryo-electron microscopy, we solved the structure of such a PSII assembly intermediate from Thermosynechococcus elongatus at 2.94 Å resolution. It contains three assembly factors (Psb27, Psb28, Psb34) and provides detailed insights into their molecular function. Binding of Psb28 induces large conformational changes at the PSII acceptor side, which distort the binding pocket of the mobile quinone (QB) and replace the bicarbonate ligand of non-heme iron with glutamate, a structural motif found in reaction centers of non-oxygenic photosynthetic bacteria. These results reveal novel mechanisms that protect PSII from damage during biogenesis until water splitting is activated. Our structure further demonstrates how the PSII active site is prepared for the incorporation of the Mn4CaO5 cluster, which performs the unique water splitting reaction