3 resultados para Modified barrier method

em AMS Tesi di Laurea - Alm@DL - Università di Bologna


Relevância:

30.00% 30.00%

Publicador:

Resumo:

During this project we have synthetized different compounds belonging to the class of amino-boranes for the study of bis-aryl-B=N system. We have decided to keep unchanged the aryl components and change only the amine to observe the effect of that on the B=N bond. The used amines are modified carbazoles with functional groups chosen to amplify or disempower the steric and the conjugation effect. We have found that the evaluation of steric barrier was possible studying the gearing aryls rotation around the C-B bonds, while the conjugation barrier is instead given by the energy needed to break the formal double bond B=N and allow the amine rotation. The work started with a proposed synthesis, improved for every reaction, then the products are characterized by NMR, fluorometric spectroscopy, mass spectrometry and X-Ray diffraction on single crystal. The following study on rotational energy barrier was possible theoretically through DFT calculation and experimentally with techniques like Dynamic NMR and EXSY. The fluorometric analysis was done for the study of the solvatochromic propriety of the products.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The waterproofing of hydraulic structure is done traiditionally like laying road on dam surface but with specific modified binders. An italian firm recently patented a new method that is re-adaptation of typical surface treatment of roads. The purpose of this study is to find out best aggregate-bitumen mixture that can perform well under service conditions of a large hydraulic structure such as dams. So, 4 different hard modified bitumen were tested with 2 aggregate types i.e. limestone and basalt. The experimental program contained the testing of bitumen aggregate adhesion, using the rolling bottle test and rheology of hard modified binders using multiple stress creep and recovery test and dynamic viscosity test. The results and discussion are presented in detail in this work.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Electrochemical hydrogen loading is a technique used to produce and study the hydrogenation in metals starting from a liquid solution containing water. It is a possible alternative to another, well-established technique which loads hydrogen starting from its gas phase. In this work, the electrochemical method is used to understand the fundamental thermodynamics of hydrogen loading in constraint systems such as thin films on substrates, and possibly distinguish the role of interfaces, stresses and microstructure during the hydrogenation process. The systems under study are thin films of Pd, Mg/Pd, and Ti/Mg multilayers. Possible future technological applications may be in the field of hydrogen storage and hydrogen sensors. Towards the end, the experimental setup is modified by introducing an automatic relay. This change leads to improvements in the data analysis and in the attainable information on the kinetics of the systems.