Thermodynamics of quark matter with multiquark clusters in an effective Beth-Uhlenbeck type approach

We describe multiquark clusters in quark matter within a Beth-Uhlenbeck approach in a background gluon field coupled to the underlying chiral quark dynamics using the Polyakov gauge which establishes the center symmetry of color SU(3) that suppresses colored states as an aspect of confinement. Quark confinement is modeled by a large quark mass in vacuum motivated by a confining density functional approach. A multiquark cluster containing $n$ quarks and antiquarks is described as a binary composite of smaller subclusters $n_1$ and $n_2$ ($n_1+n_2=n$). It has a spectrum consisting of a bound state and a scattering state continuum. For the corresponding cluster-cluster phase shifts we discuss simple ans\"atze that capture the Mott dissociation of clusters as a function of temperature and chemical potential. We go beyond the simple "step-up-step-down" model that ignores continuum correlations and introduce an improved model that includes them in a generic form. In order to explain the model, we restrict ourselves here to the cases where the cluster size is $1 \le n \le 6$. A striking result is the suppression of the abundance of colored multiquark clusters at low temperatures by the coupling to the Polyakov loop and their importance for a quantitative description of lattice QCD thermodynamics at non-vanishing baryochemical potentials. An important ingredient are Polyakov-loop generalized distribution functions of $n$-quark clusters which are derived here for the first time. Within our approach we calculate thermodynamic properties such as baryon density and entropy. We demonstrate that the limits of a hadron resonance gas at low temperatures and $\mathcal{O}(g^2)$ perturbative QCD at high temperatures are correctly reproduced. A comparison with lattice calculations shows that our model is able to give a unified, systematic approach to describe properties of the quark-gluon-hadron system.Comment: 20 pages, 11 figures, 6 table

The crucible/silicon interface in directional solidification of photovoltaic silicon

International audiencePhotovoltaic silicon ingots are currently grown in silica crucibles coated with a porous silicon nitride layer which acts as an interface releasing agent between the silicon and the crucible. The interactions between Si and the Si3N4 coating determine the infiltration and sticking phenomena occurring at the interface and also affect the pollution of Si by the components of the coating. In this investigation the interfacial interactions and microstructure are studied in crystallization experiments performed in crucibles involving high silicon masses (tens of kg) and long contact time between the silicon and the coated silica (tens of hours). It is shown that for long times, a dramatic change in the nature of the coating/Si interface takes place, with the formation of a self-crucible which prevents the direct contact between the silicon and the coating. The stability of the self-crucible is modeled taking into account the capillary and hydrostatic pressures. The influence of the self-crucible on different practical aspects of the photovoltaic silicon crystallization process is discussed. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Analysis of the incidence of postintubation injuries in patients intubated in the prehospital or early hospital conditions of the hospital emergency department and the intensive care unit

Marcin Cierniak,1 Dariusz Timler,1 Renata Sobczak,1 Andrzej Wieczorek,2 Przemyslaw Sekalski,3 Natalia Borkowska,2 Tomasz Gaszynski1 1Department of Emergency Medicine and Disaster Medicine, Barlicki University Hospital, 2Department of Anesthesiology and Intensive Therapy, Medical University of Lodz, 3Department of Microelectronics and Computer Science, IT Centre, Lodz University of Technology, Lodz, Poland Background: Intubation is still one of the best methods to secure the airway. In the case of prehospital or early hospital conditions when factors such as urgency, stress, or inaccuracy of the undertaken activities are involved, the risk of causing complications, for instance, edema or postintubation injuries, increases, especially while dealing with a difficult intubation. The risk of improper inflation of the endotracheal tube cuff also increases, which is considered in this study.Objective: The aim of this study was to evaluate the prevalence of postintubation complications, such as postintubation injuries or edema, in a research sample, and to examine whether such complications occur more often, for example, while using a guidewire. In this study, we also evaluated the injuries associated with the inflation of the endotracheal tube cuff.Materials and methods: This study was performed on a group of 153 patients intubated in prehospital conditions. The tests were carried out in three clinical sites that received patients from prehospital care. Postintubation injuries were revealed and photographed using videolaryngoscope, such as the C-MAC and the McGrath series 5. The endotracheal tube cuff pressure was measured using a pressure gage manual (VBM Medizintechnik GmbH). The quantitative analyses of differences between incidence of variables were assessed using χ2 test for P<0.05. Analyses have been carried out using the Statistica software.Results: In the group of 153 patients, postintubation injuries occurred in 17% of cases. The dependency between using the guidewire and the occurrence of the hematomas and loss of mucosa was statistically significant (P<0.01). In nearly half (42%) of the patients the endotracheal tube cuff pressure was excessively inflated over 30 cm H2O, and in two cases, endotracheal tube displacement was observed on account of poor cuff inflation (<20 cm H2O).Conclusion: The highest percentage of overfilled cuffs were observed in the admission room. In the other wards, it was observed in 25% of cases. Even though only six cases of poor cuff inflation were noticed, the relationship between the leakage and the clinical conditions of patients is worth examining. The results would help in taking additional measures to reduce the risk of complications. Keywords: postintubation injuries, postintubation edema, endotracheal tube cuff pressur