Microscopic Identification of Progressive Fracturing in Granite Under Triaxial and Uniaxial Stress Conditions from Bátaapáti Radwaste Repository

The program for the final disposal of low and intermediate level radioactive waste was established by Paks Nuclear Power Plant, Hungary. Preparation of final disposal has been done as part of a national program since 1993. The Central Nuclear Financial Fund and the Public Limited Company for Radioactive Waste Management (PURAM) have been established to coordinate organizations and activities for all tasks in connection, with nuclear waste treatment. The project was started with a geological screening in order to find the most suitable geological formation for a radioactive waste repository. The selected potential host rock is the Mórágy Granite Formation in the south-western part of Hungary, close to the village of Bátaapáti.This paper show and explain the results of an extensive study of the deformation and fracturing of Mórágy granite samples under uniaxial and triaxial loading conditions. In the investigation, the stress fracturing thresholds (crack initiation, crack coalescence and crack damage) were determined using stress–strain and stiffness curves without acoustic emission (AE) detection technique. Crack initiation was found to be best determined by the volumetric strain curve in both uniaxial and triaxial compression tests. As a detailed investigation, a comprehensive petrographical analysis using a petrological microscope was performed to identify the mode of cracking and the characterization of the cracking pattern

Optimization of activator solution and heat treatment of ground lignite type fly ash geopolymers

Geopolymers are inorganic polymers which can be produced by the reaction between silico aluminate oxides and alkali silicates in alkaline medium. Materials containing silica and alumina compounds are suitable for geopolymer production. These can be primary materials or industrial wastes, i. e. fly ash, metallurgical slag and red mud. In this paper, the results of the systematic experimental series are presented which were carried out in order to optimize the geopolymer preparation process. Fly ash was ground for different residence time (0, 5, 10, 30, 60 min) in order to investigate the optimal specific surface area. NaOH activator solution concentration also varied (6, 8, 10, 12, 14 M). Furthermore, sodium silicate was added to NaOH as a network builder solution. In this last serie different heat curing temperatures (30, 60, 90°C) were also applied. After seven days of ageing the physical properties of the geopolymer(compressive strength and specimen density)were measured. Chemical leaching tests on the rawmaterial and the geopolymers were carried out to determine the elements which can be mobilized by different leaching solutions. It was found that the above mentioned parameters (fly ash fineness, molar concentration and composition of activator solution, heat curing) has great effect on the physical and chemical properties of geopolymer specimens. Optimal conditions were as follows: specific surface area of the fly ash above 2000 cm2/g, 10 M NaOH, 30o C heat curing temperature which resulted in 21 MPa compressive strength geopolymer

Structural formation and leaching behavior of mechanically activated lignite fly ash based geopolymer

Geopolymers are inorganic polymers which can be produced by the reaction of aluminium silicate oxides and alkaline silicates in an alkaline medium. Nowadays, silicate bearing wastes, such as fly ash or slag and other by-products of power stations are very common raw materials for geopolymers. In our research a lignite type fly ash was mechanically activated in a high energy density mill (HEM) for different retention time, and geopolymer specimens were produced from these materials. After determining the optimal fly ash fineness, the concentration and composition of the alkaline activator solution were also investigated. The highest compressive strength was reached using fly ash with 2 m2/g specific surface area, activated with a mixture of Na-K silicate (water glass) and NaOH solution. The total dosage of alkaline activators to the fly ash was 40 m/m%, the NaOH activator of 12 M solution represented 25 m/m %, while Na-K silicate 75 m/m%. Then, the leaching properties of the main components and the mobility of toxic elements of the produced geopolymers were tested in distilled water, 1M acetic acid and 1M hydrochloric acid as well. The lowest mobility of the elements was obtained in most cases by the activator containing 100m/m% Na-K silicate solution (water glass) using the mechanically activated fly ash

Electrocyclization and Unexpected Reactions of Non-Stabilized α,β:γ,δ-Unsaturated Azomethine Ylides: Experimental and Theoretical Studies

This project was supported by National Research, Development and Innovation Fund of Hungary, financed under the (OTKA PD128612) funding scheme. The authors are grateful to the Bolyai Research Scholarship of the Hungarian Academy of Sciences (BO/799/21/7), the ÚNKP-21-5 new National Excellence Program, NVKP-16 (1-2016-0043), KFI-16 (1-2016-0177), KFI-18 (00097) and VKE-18 (00032) of the Ministry for Innovation and Technology from the Source of the National Research, Development and Innovation Fund for financial support

Synthesis and Fluorescence Mechanism of the Aminoimidazolone Analogues of the Green Fluorescent Protein: Towards Advanced Dyes with Enhanced Stokes Shift, Quantum Yield and Two-Photon Absorption

Novel small-molecular analogues the green fluorescence protein (GFP) chromophore are synthesised to expand and improve this fluorophore family and to deepen the understanding of their fluorescence mechanism. The introduction of an aminophenyl substituent and the repositioning of the hydroxyl group to enable strong intramolecular hydrogen bonding, not only enhances fluorescence emission, but also results in an increased Stokes shift and a considerable red shift. Experimental and computational results describe a dual fluorescence involving both excited-state intramolecular proton transfer and internal charge transfer (ESIPT?ICT) mechanism. The further improvement of the photophysical properties via the systematic variation of dialkylamino substituents at a single position of the chromophore led to a two-orders of magnitude enhancement in the quantum yields. In addition, the novel compounds also have significant two-photon absorption, which widens the possibilities for applications in the field of bioimaging