Tallinn University of Technology

About: Tallinn University of Technology is a education organization based out in Tallinn, Estonia. It is known for research contribution in the topics: European union & Oil shale. The organization has 3688 authors who have published 10313 publications receiving 145058 citations. The organization is also known as: Tallinn Technical University & Tallinna Tehnikaülikool.

Design and implementation of fractional-order PID controllers for a fluid tank system

Abstract: In this paper, we investigate the practical problems of design and digital implementation of fractional-order PID controllers used for fluid level control in a system of coupled tanks. We present a method for obtaining the PIλDμ controller parameters and describe the steps necessary to obtain a digital implementation of the controller. A real laboratory plant is used for the experiments, and a hardware realization of the controller fit for use in embedded applications is proposed and studied. The majority of tasks is carried out by means of the FOMCON (“Fractional-order Modeling and Control”) toolbox running in the MATLAB computing environment.

Interaction of firefly luciferase and silver nanoparticles and its impact on enzyme activity

Abstract: We report on the dose-dependent inhibition of firefly luciferase activity induced by exposure of the enzyme to 20 nm citrate-coated silver nanoparticles (AgNPs). The inhibition mechanism was examined by characterizing the physicochemical properties and biophysical interactions of the enzyme and the AgNPs. Consistently, binding of the enzyme induced an increase in zeta potential from −22 to 6 mV for the AgNPs, triggered a red-shift of 44 nm in the absorbance peak of the AgNPs, and rendered a 'protein corona' of 20 nm in thickness on the nanoparticle surfaces. However, the secondary structures of the enzyme were only marginally affected upon formation of the protein corona, as verified by circular dichroism spectroscopy measurement and multiscale discrete molecular dynamics simulations. Rather, inductively coupled plasma mass spectrometry measurement revealed a significant ion release from the AgNPs. The released silver ions could readily react with the cysteine residues and N-groups of the enzyme to alter the physicochemical environment of their neighboring catalytic site and subsequently impair the enzymatic activity.

Ferromagnetism in rare earth doped cerium oxide bulk samples

Abstract: Magnetic properties of rare earth (RE) doped ceria (RE = Nd, Sm, Gd, Tb, Er and Dy) samples have been investigated and reported in this paper. Room temperature ferromagnetism (FM) was observed in calcined powders as well as in sintered samples of Nd and Sm doped CeO2, whereas other RE dopants (Gd, Tb, Er and Dy) in CeO2 exhibit paramagnetic behaviour. The origin of magnetism in these samples can be related to oxygen vacancies and formation of fluorite crystal structure. Though the magnetization was found to be lower as compared to transition metal (TM) doped ceria, the segregation of metallic and secondary phases can be avoided in RE doped CeO2. CeO2 doped with Sm ions in different concentration (1, 5 and 15%) were also studied to see the dopant effects on magnetic properties. The origin of magnetism in these samples may be related to the oxygen vacancies created due to RE dopants, which was confirmed from the peak around 555 cm−1 in Raman spectra.