Molecular dynamics simulations have been widely adopted to study oxygen ion diffusion mechanisms in materials for application in solid oxide fuel cells. Indeed, understanding the fundamental aspects of oxygen diffusion is important to develop new materials for this application. In this work, Nd1-xAExBaInO4-x/2 (AE = Ca, Sr, Ba) compounds have been studied by MD simulations focusing on oxygen diffusion mechanisms.
View Article and Find Full Text PDFJ Phys Chem A
October 2019
In the present work, we have investigated the possibility of using the quantum thermal bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is used in introducing nuclear quantum effects with a computational time, which is basically the same as in Newtonian simulations. At this end, we have considered the model fragmentation of CH for which an analytical function is present in the literature.
View Article and Find Full Text PDFThe isotope effect on the collective proton/deuteron transfer in hydrogen and deuterium fluoride crystals has been investigated at 100 K by ab initio quantum-thermal-bath path-integral molecular dynamics (QTB-PIMD) simulation. The deuterons within a planar zigzag chain of the orthorhombic structure simultaneously flip between covalent and hydrogen bonds due to the barrier crossing through tunnelling. The height of the corresponding static barrier normalized for one deuteron is 29.
View Article and Find Full Text PDFJ Chem Theory Comput
December 2016
The quantum thermal bath (QTB) has been presented as an alternative to path-integral-based methods to introduce nuclear quantum effects in molecular dynamics simulations. The method has proved to be efficient, yielding accurate results for various systems. However, the QTB method is prone to zero-point energy leakage (ZPEL) in highly anharmonic systems.
View Article and Find Full Text PDFJ Chem Theory Comput
March 2016
The quantum thermal bath (QTB) method has been recently developed to account for the quantum nature of the nuclei by using standard molecular dynamics (MD) simulation. QTB-MD is an efficient but approximate method when dealing with strongly anharmonic systems, while path integral molecular dynamics (PIMD) gives exact results but in a huge amount of computation time. The QTB and PIMD methods have been combined in order to improve the PIMD convergence or correct the failures of the QTB-MD technique.
View Article and Find Full Text PDFPurpose: To analyse the impact of acetazolamide (ACET) use in severe acute decompensation of chronic obstructive pulmonary disease requiring mechanical ventilation and intensive care unit (ICU) admission.
Patients And Methods: Retrospective pair-wise, case-control study with 1:1 matching. Patients were defined as cases when they had received acetazolamide (500 mg per day) and as controls when they did not received it.
Background And Objectives: Quantitative real time PCR (qPCR) offers rapid diagnosis of rickettsial infections. Thus, successful treatment could be initiated to avoid unfavorable outcome. Our aim was to compare two qPCR assays for Rickettsia detection and to evaluate their contribution in early diagnosis of rickettsial infection in Tunisian patients.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
February 2015
A new organic-inorganic material, diethylenetriammonium hexabromobismuthate (C4H16N3)BiBr6, was synthesized and characterized by X-ray diffraction, infrared absorption, Raman spectroscopy scattering and optical absorption. The crystal lattice is composed of discrete [BiBr6] anions surrounded by diethylenetriammonium cations. The title compound crystallizes in the non-centro-symmetric space group P212121 of orthorhombic system.
View Article and Find Full Text PDFRelaxor ferroelectric perovskites are highly polarizable and can exhibit giant coupling between elastic strain and an applied electric field. Here, we report an in situ extended X-ray absorption fine structure (EXAFS) study of a PbZn1/3Nb2/3O3 (PZN) single crystal as a function of the electric field. We show that the strong dipoles in the NbO6 octahedra bonds are aligned along the four ⟨011⟩ directions close to the orientation of the electric field, while a small reversible polar shift occurs for Zn in the direction of the electric field, i.
View Article and Find Full Text PDFPurpose: We aimed to determine the incidence and the prognostic impact [mortality and length of intensive care unit (ICU) stay (LOS)] of pulmonary embolism (PE) in critically ill patients with severe acute exacerbation of chronic obstructive pulmonary disease (COPD).
Methods: This is a retrospective study performed during a 5-year period in the ICU of Habib Bourguiba University Hospital (Sfax, Tunisia). All patients with severe acute exacerbation of COPD were included.
Purpose: To describe the epidemiologic features of acute renal failure related to pregnancy (PRARF) and to evaluate its prognostic impact.
Methods: Retrospective study conducted in a Tunisian intensive care unit over a period of 17 years (1995-2011). Women were included if they were more than 20 weeks pregnant and were admitted to the ICU during pregnancy or immediately (<7 d) post partum.
Background: To analyse the efficacy and safety of systemic infusion of hydrocortisone hemisuccinate in children admitted to the intensive care unit with severe scorpion envenomation, we assessed the impact on mortality and length of hospital stay.
Method: We conducted a pair-wise, case-control study with 1:1 matching, reviewing records over a 13-year period (1990-2002) for the intensive care unit (ICU) of the Habib Bourguiba University Hospital, Sfax, Tunisia. A total of 184 children were included in the study (92 cases and 92 controls); cases received hydrocortisone hemisuccinate during hospitalization and controls received no steroids.
The aim of this study is to analyze if the infusion of hydrocortisone hemisuccinate improve outcome in severe scorpion-envenomated adult patients admitted to intensive care unit (ICU). Pairwise retrospective case-control study with 1:1 matching was designed. Patients were defined as cases when they received hydrocortisone hemisuccinate (as alone steroids) during hospitalization and as controls when they did not received any steroids.
View Article and Find Full Text PDFUp to 2008, dopamine was the catecholamine that was the most recommended in our intensive care unit (ICU) after fluid resuscitation. However, recently, norepinephrine has become the catecholamine that was most recommended in our ICU after fluid resuscitation. The aim of this study was to determine if there was an efficacy or safety benefit to this protocol therapeutic change in patients with shock admitted to our ICU.
View Article and Find Full Text PDFThe incidence of ventilator-associated pneumonia (VAP) is particularly high in patients with trauma. The efficacy and safety of selective digestive decontamination (SDD) was not studied extensively. We aimed in our randomized double-blind, placebo-controlled study to evaluate whether SDD prevents VAP onset in multiple trauma patients.
View Article and Find Full Text PDFThe purpose of this study was to analyze the efficacy of corticosteroids in severe acute decompensation of chronic obstructive pulmonary disease requiring mechanical ventilation and intensive care unit (ICU) admission. Pairwise retrospective case-control study with 1:1 matching. Patients were defined as cases when they received corticosteroids and as controls when they did not received any steroids.
View Article and Find Full Text PDFMolecular dynamics (MD) simulations have been carried out to study isotope effects in lithium hydride and lithium deuteride crystals. Quantum effects on nuclear motion have been included through a quantum thermal bath (QTB). The interatomic forces were described either within the density functional theory (DFT) in the generalized gradient approximation (GGA) or by the phenomenological approach using the shell model.
View Article and Find Full Text PDFBackground: Hypotension and shocks are frequently observed in patients requiring admission in ICU. However, the optimal adrenergic support in shock is controversial.
Aim: To perform a descriptive approach of the current use of catecholamine in a medico-surgical ICU in patients with schoks.
Ann Cardiol Angeiol (Paris)
September 2015
We report the case of a severe acute pulmonary edema secondary to the administration of salbutamol to a patient admitted for severe asthma. The diagnosis of acute pulmonary edema was suspected on the clinical examination, chest radiography, biological (plasmatic Pro-BNP rate) and echocardiographic findings. Rapid improvement under dobutamine and mechanical ventilation argue in favour of cardiogenic pulmonary edema.
View Article and Find Full Text PDFIntroduction: Drugs' administration via feeding tubes is a potential source of iatrogenic events for the intensive care patients because of the problem of not adapted galenic forms.
Objectives: We analyzed the prescriptions of patients with enteral feedings to determine if the galenic forms were compatible with administration via feeding tubes. We also observed and analyzed the methods of drugs passage by nurses.
Scorpion envenomation is common in tropical and subtropical regions. Cardio-respiratory manifestations, mainly cardiogenic shock and pulmonary edema, are the leading causes of death after scorpion envenomation. The mechanism of pulmonary edema remains unclear and contradictory conclusions were published.
View Article and Find Full Text PDFObjective: To determine the predictive factors, clinical manifestations, and the outcome of patients with post-traumatic pulmonary embolism (PE) admitted in the intensive care unit (ICU).
Methods: During a four-year prospective study, a medical committee of six ICU physicians prospectively examined all available data for each trauma patient in order to classify patients according to the level of clinical suspicion of pulmonary thromboembolism. During the study period, all trauma patients admitted to our ICU were classified into two groups.
Purpose: To identify factors correlated with poor outcome and factors correlated with acute kidney injury (AKI) onset in critically A(H1N1) infected patients.
Methods: All patients admitted for respiratory distress due to a confirmed infection by A(H1N1) virus were included retrospectively.
Results: Thirty-four patients were included.