In Vitro

Epigallocatechin-3-gallate (EGCG) is the main compound of green tea with well-described antioxidant, anti-inflammatory, and tumor-suppressing properties. However, EGCG at high doses was reported to cause liver injury. In this study, we evaluated the effect of EGCG on primary culture of rat hepatocytes and on rat liver mitochondria in permeabilized hepatocytes. The 24-hour incubation with EGCG in concentrations of 10 μmol/L and higher led to signs of cellular injury and to a decrease in hepatocyte functions. The effect of EGCG on the formation of reactive oxygen species (ROS) was biphasic. While low doses of EGCG decreased ROS production, the highest tested dose induced a significant increase in ROS formation. Furthermore, we observed a decline in mitochondrial membrane potential in cells exposed to EGCG when compared to control cells. In permeabilized hepatocytes, EGCG caused damage of the outer mitochondrial membrane and an uncoupling of oxidative phosphorylation. EGCG in concentrations lower than 10 μmol/L was recognized as safe for hepatocytes in vitro

Partonic collectivity in large and small systems at the LHC

Under extreme conditions, such as high temperature and density, quarks and gluons can be deconfined. The deconfined matter, quark-gluon plasma (QGP), that existed within the first microsecond after the Big Bang, can be recreated in ultra-relativistic heavy-ion collisions at particle accelerators. One way to investigate the initial conditions and the dynamic evolution of such a collectively expanding medium is by studying the anisotropic flow, quantified by flow coefficients $v_n$. Experimental measurements of the QGP from various flow observables show remarkable agreement with the hydrodynamic calculations, suggesting the QGP behaves like a nearly ideal fluid. The collective behaviour associated with the presence of QGP is also observed in small collision systems at very high multiplicities with significantly more produced particles than in an average small system collision. Based on the existing studies, it is known that the anisotropic flow in small systems is mainly driven by the initial geometry of the system. However, the development of flow from the initial geometry through the dynamic evolution is still under discussion. In this thesis, the anisotropic flow is studied using different observables and across different collision systems. A new generic algorithm is developed to formulate multi-particle cumulants of arbitrary order in Pb--Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. The measurements of multi-particle cumulants of single and mixed harmonics are reported. \linebreak Mixed harmonic cumulants $MHC(v_m^k,v_n^l)$ have a unique sensitivity to the initial conditions. Thus, the results are compared to the calculations from hydrodynamical models in order to constrain initial conditions and transport properties of the QGP. The flow coefficients $v_2(p_{\rm T})$ are calculated using the two- and four-particle cumulants method. With these observables, it is possible to study the first two moments of the probability density function of elliptic flow, the mean $\langle v_2 \rangle$ and variance $\sigma_{v_{2}}$, and the relative flow fluctuations of identified particles for the first time in heavy-ion collisions. Moreover, the elliptic flow $v_2(p_{\rm T})$ with various identified particle species is studied in Pb--Pb collisions to further probe the initial conditions and properties of QGP, in particular, the particle production mechanisms, e.g., quark coalescence. The flow measurements of identified particles in heavy-ion collisions bring a unique insight into initial conditions and the properties of QGP. Therefore, such a study in small collision systems can contribute to understanding the role of initial conditions and the state of the recreated matter. However, the study of flow coefficients in small systems is more challenging due to significant non-flow contamination. The measurement is performed in p--Pb and pp collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ and 13 TeV, respectively. Thanks to the unique pseudorapidity coverage of ALICE, the flow coefficients with sufficient non-flow suppression are obtained using ultra-long-range two-particle correlations and the template fit method. Many similarities are observed in flow in large and small systems. The measured $v_2(p_{\rm T})$ coefficients exhibit mass ordering in the low transverse momentum region. Such a phenomenon originates from the radial expansion of the system. The baryon-meson grouping at the intermediate transverse momentum, which in Pb--Pb is typically associated with partonic collectivity and quark coalescence, is also reported in p--Pb and pp collisions. These observations are discussed in the context of models with and without the contribution of quark coalescence. The similarities between large and small systems show strong evidence that a droplet of QGP is created in small collision systems at high multiplicities

Analysis of the TOF single-channel performance by using cosmic rays triggered in the ALICE experiment during the 2016/17 data taking campaign

The ALICE Time-Of-Flight detector has well defined time resolution of 56 ps for the beam data. In this work project report, the analysis of cosmic rays is presented with the focus on receiving the time resolution for different levels of granularity of TOF. The obtained value (approx. 90 ps if there is a sufficient statistics) is uniform through different momentum bins, geometry of the detector and readout electronics as well

Generic algorithm for multiparticle cumulants of azimuthal correlations in high energy nucleus collisions

Multi-particle cumulants of azimuthal angle correlations have been compelling tools to probe the properties of the Quark-Gluon Plasma (QGP) created in the ultra-relativistic heavy-ion collisions and the search for the QGP in small collision systems at RHIC and the LHC. However, only very few of them are available and have been studied in theoretical calculations and experimental measurements. In this paper, we present a generic recursive algorithm for multi-particle cumulants, which enables the calculation of arbitrary order multi-particle cumulants. Among them, the new 10-, 12-, 14-, and 16-particle cumulants of a single harmonic, named $c_{n}\{10\}$, $c_{n}\{12\}$, $c_{n}\{14\}$, and $c_{n}\{16\}$, and the corresponding $v_n$ coefficients, will be discussed for the first time. These new multi-particle cumulants can be readily used along with updates to the generic framework of multi-particle correlations to a very high order. Finally, we propose a particular series of mixed harmonic multi-particle cumulants, which measures the general correlations between any moments of different flow coefficients. The predictions of these new observables are shown based on an initial state model MC-Glauber, a toy Monte Carlo model, and the HIJING transport model for future comparisons between experimental data and theoretical model calculations. The study of these new multi-particle cumulants in heavy-ion collisions will significantly improve the understanding of the joint probability density function which involves both different harmonics of flow and also the symmetry planes. This will pave the way for more stringent constraints on the initial state and help to extract more precisely how the created hot and dense matter evolves. Meanwhile, the efforts applied to small systems could be very helpful in the understanding of the origin of the observed collectivity at RHIC and the LHC.Comment: 13 pages, 6 figure