Mutual entrainment effects in cold neutron-proton mixtures are studied in the framework of the self-consistent nuclear energy-density functional theory. Exact expressions for the mass currents, valid ...for both homogeneous and inhomogeneous systems, are directly derived from the time-dependent Hartree-Fock equations with no further approximation. The equivalence with the Fermi-liquid expression is also demonstrated. Focusing on neutron-star cores, a convenient and simple analytical formulation of the entrainment matrix in terms of the isovector effective mass is found, thus allowing to relate entrainment phenomena in neutron stars to isovector giant dipole resonances in finite nuclei. Results obtained with different functionals are presented. These include the Brussels-Montreal functionals, for which unified equations of state of neutron stars have been recently calculated.
Mutual entrainment effects in hot neutron-proton superfluid mixtures are studied in the framework of the self-consistent nuclear energy-density functional theory. The local mass currents in ...homogeneous or inhomogeneous nuclear systems, which we derive from the time-dependent Hartree-Fock-Bogoliubov equations at finite temperatures, are shown to have the same formal expression as the ones we found earlier in the absence of pairing at zero temperature. Analytical expressions for the entrainment matrix are obtained for application to superfluid neutron-star cores. Results are compared to those obtained earlier using Landau's theory. Our formulas, valid for arbitrary temperatures and currents, are applicable to various types of functionals including the Brussels-Montreal series for which unified equations of state have been already calculated, thus laying the ground for a fully consistent microscopic description of superfluid neutron stars.
Temperature and velocity-dependent \(^1\)S\(_0\) pairing gaps, chemical potentials and entrainment matrix in dense homogeneous neutron-proton superfluid mixtures constituting the outer core of ...neutron stars, are determined fully self-consistently by solving numerically the time-dependent Hartree-Fock-Bogoliubov equations over the whole range of temperatures and flow velocities for which superfluidity can exist. Calculations have been made for \(npe\mu\) in beta-equilibrium using the Brussels-Montreal functional BSk24. The accuracy of various approximations is assessed and the physical meaning of the different velocities and momentum densities appearing in the theory is clarified. Together with the unified equation of state published earlier, the present results provide consistent microscopic inputs for modeling superfluid neutron-star cores.
Chlorine dioxide (ClO2) is commonly used as an alternative disinfectant to chlorine in drinking water treatment because it produces limited concentrations of halogenated organic disinfection ...byproducts. During drinking water treatment, the primary ClO2 byproducts are the chlorite (50–70%) and the chlorate ions (0–30%). However, a significant portion of the ClO2 remains unaccounted for. This study demonstrates that when ClO2 was reacting with phenol, one mole of free available chlorine (FAC) was produced per two moles of consumed ClO2. The in situ formed FAC completed the mass balance on Cl for inorganic ClO2 byproducts (FAC + ClO2 + ClO3 ). When reacting with organic matter extracts at near neutral conditions (pH 6.5–8.1), ClO2 also yielded a significant amount of FAC (up to 25%). Up to 27% of this in situ formed FAC was incorporated in organic matter forming adsorbable organic chlorine, which accounted for up to 7% of the initial ClO2 dose. Only low concentrations of regulated trihalomethanes were produced because of an efficient mitigation of their precursors by ClO2 oxidation. Conversely, dichloroacetonitrile formation from ClO2-induced generation of FAC was higher than from addition of FAC in absence of ClO2. Overall, these findings provide important information on the formation of FAC and disinfection byproducts during drinking water treatment with ClO2.
•Chemical oxidation abates the electron donating capacity (EDC) more efficiently than UV254.•The efficiency on UV254 abatement ranked O3 > Mn(VII) > Fe(VI)/ClO2.•The efficiency on EDC abatement ...ranked Mn(VII) > ClO2 > Fe(VI) > O3.•Good correlation between EDC abatement and haloacetonitrile mitigation.
Pre-oxidation is often used before disinfection with chlorine to decrease the reactivity of the water matrix and mitigate the formation of regulated disinfection byproducts (DBPs). This study provides insights on the impact of oxidative pre-treatment with chlorine dioxide (ClO2), ozone (O3), ferrate (Fe(VI)) and permanganate (Mn(VII)) on Suwannee River Natural Organic Matter (SRNOM) properties characterized by the UV absorbance at 254 nm (UV254) and the electron donating capacity (EDC). Changes in NOM reactivity and abatement of DBP precursors are also assessed. The impact of pre-oxidants (based on molar concentration) on UV254 abatement ranked in the order O3 > Mn(VII) > Fe(VI)/ClO2, while the efficiency of pre-oxidation on EDC abatement followed the order Mn(VII) > ClO2 > Fe(VI) > O3 and two phases were observed. At low specific ClO2, Fe(VI) and Mn(VII) doses corresponding to < 50% EDC abatement, a limited relative abatement of UV254 compared to the EDC was observed (~ 8% EDC abatement per 1% UV254 abatement). This suggests the oxidation of phenolic-type moieties to quinone-type moieties which absorb UV254 and don't contribute to EDC. At higher oxidant doses (> 50% EDC abatement), a similar abatement of EDC and UV254 (~ 0.9–1.2% EDC abatement per 1% UV254 abatement) suggested aromatic ring cleavage. In comparison to the other oxidants, O3 abated the relative UV254 more effectively, due to a more efficient cleavage of aromatic rings. For a pre-oxidation with Mn(VII), ClO2 and Fe(VI), similar correlations between the EDC abatement and the chlorine demand or the adsorbable organic halide (AOX) formation were obtained. In contrast, O3 pre-treatment led to a lower chlorine demand and AOX formation for equivalent EDC abatement. For all oxidants, trihalomethane formation was poorly correlated with both EDC and UV254. The EDC abatement was found to be a pre-oxidant-independent surrogate for haloacetonitrile formation. These results emphasize the benefits of combining EDC and UV254 measurement to understand and monitor oxidant-induced changes of NOM and assessing DBP formation.
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Ferrate (Fe(VI)) is a novel oxidant that can be used to mitigate disinfection byproduct (DBP) precursors. However, the reaction of Fe(VI) with organic nitrogen, which is a potential precursor of ...potent nitrogenous DBPs, remains largely unexplored. The present work aimed to identify the kinetics and products for the reaction of Fe(VI) with primary amines, notably amino acids. A new kinetic model involving ionizable intermediates was proposed and can describe the unusual pH effect on the Fe(VI) reactivity toward primary amines and amino acids. The Fe(VI) oxidation of phenylalanine produced a mixture of nitrile, nitrite/nitrate, amide, and ammonia, while nitroalkane was an additional product in the case of glycine. The product distribution for amino acids significantly differed from that of uncarboxylated primary amines that mainly generate nitriles. A general reaction pathway for primary amines and amino acids was proposed and notably involved the formation of imines, the degradation of which was affected by the presence of a carboxylic group. In comparison, ozonation led to higher yields of nitroalkanes that could be readily converted to potent halonitroalkanes during chlor(am)ination. Based on this study, Fe(VI) can effectively mitigate primary amine-based, nitrogenous DBP precursors with little formation of toxic halonitroalkanes.
•Chlorite oxidation by chlorine can be modelled in pure and synthetic waters.•Chlorate (60–70%) and ClO2 (30–40%) are formed from chlorite oxidation.•Predicting chlorite and chlorate can help to ...optimize ClO2 preoxidation.•Increasing ClO2 dose can improve disinfection byproduct mitigation.•A trade-off between inorganic and organic byproduct formation is needed.
Chlorine dioxide (ClO2) applications to drinking water are limited by the formation of chlorite (ClO2–) which is regulated in many countries. However, when ClO2 is used as a pre-oxidant, ClO2– can be oxidized by chlorine during subsequent disinfection. In this study, a kinetic model for the reaction of chlorine with ClO2– was developed to predict the fate of ClO2– during chlorine disinfection. The reaction of ClO2– with chlorine was found to be highly pH-dependent with formation of ClO3– and ClO2 in ultrapure water. In presence of dissolved organic matter (DOM), 60-70% of the ClO2– was transformed to ClO3– during chlorination, while the in situ regenerated ClO2 was quickly consumed by reaction with DOM. The remaining 30-40% of the ClO2– first reacted to ClO2 which then formed chlorine from the DOM-ClO2 reaction. Since only part of the ClO2– was transformed to ClO3–, the sum of the molar concentrations of oxychlorine species (ClO2– + ClO3–) decreased during chlorination. By kinetic modelling, the ClO2– concentration after 24 h of chlorination was accurately predicted in synthetic waters but was largely overestimated in natural waters, possibly due to a ClO2– decay enhanced by high concentrations of chloride and in situ formed bromine from bromide. Understanding the chlorine-ClO2– reaction mechanism and the corresponding kinetics allows to potentially apply higher ClO2 doses during the pre-oxidation step, thus improving disinfection byproduct mitigation while keeping ClO2–, and if required, ClO3– below the regulatory limits. In addition, ClO2 was demonstrated to efficiently degrade haloacetonitrile precursors, either when used as pre-oxidant or when regenerated in situ during chlorination.
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Current surgical robotic systems are teleoperated and do not have force feedback. Considerable practice is required to learn how to use visual input such as tissue deformation upon contact as a ...substitute for tactile sense. Thus, unnecessarily high forces are observed in novices, prior to specific robotic training, and visual force feedback studies demonstrated reduction of applied forces. Simulation exercises with realistic suturing tasks can provide training outside the operating room. This paper presents contributions to realistic interactive suture simulation for training of suturing and knot-tying tasks commonly used in robotically-assisted surgery. To improve the realism of the simulation, we developed a global coordinate wire model with a new constraint development for the elongation. We demonstrated that a continuous modeling of the contacts avoids instabilities during knot tightening. Visual cues are additionally provided, based on the computation of mechanical forces or constraints, to support learning how to dose the forces. The results are integrated into a powerful system-agnostic simulator, and the comparison with equivalent tasks performed with the da Vinci Xi system confirms its realism.
The development of optical coherence tomography (OCT) has revolutionized our understanding of coronary artery disease. In vivo OCT research has paralleled with advances in computational fluid ...dynamics, providing additional insights in the various hemodynamic factors influencing plaque growth and stability. Recent OCT studies introduced a new concept of plaque healing in relation to clinical presentation. In addition to known mechanisms of acute coronary syndromes such as plaque rupture and plaque erosion, a new classification of calcified plaque was recently reported. This review will focus on important new insights that OCT has provided in recent years into coronary plaque development, progression, and destabilization, with a focus on the role of local hemodynamics and endothelial shear stress, the layered plaque (signature of previous subclinical plaque destabilization and healing), and the calcified culprit plaque.
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