Search results for "thermodynamic"
showing 10 items of 2971 documents
Temperature changes in 2% chlorhexidine gluconate using two activation methods with different intensity levels
2018
Background Chlorhexidine is an irrigant solution widely used in root canal treatment because of its good antimicrobial properties. However, its mixture with sodium hypochlorite results in the appearance of substance called p-chloroaniline, a cytotoxic substance. This is also found when chlorhexidine is heated. The use of passive ultrasonic irrigation is related to an irrigant thermal increase, which can cause the appearance of p-chloroaniline. Thus, the objective is to establish the influence of ultrasonic and sonic activation, with the use of different intensities, upon the temperature of chlorhexidine gluconate (CHX). Material and methods The following groups were established: control (wi…
Influence d'humidité de l'air sur le séchage d'une goutte déposée sur une surface solide et sur la destruction microbienne.
2017
International audience; This study was carried out in order to develop experimental methodology using a camera to monitor the evolution of the surface of a liquid droplet deposited on a solid surface composed of polypropylene. The droplet was exposed to various ambient relative humidity conditions (11.3%, 43.2%, 68.9% and 75.5%). Two types of liquid were investigated: distilled water and water containing nutritive substances (salmon “juice”). At 11.3% relative humidity, it takes 40% longer to evaporate a water droplet (initial weight 0.36 g, volume 360 μL, radius 6.5 × 10−3 m) than a salmon “juice” droplet (3.66 h for distilled water, 2.83 h for salmon “juice”). In the case of the distilled…
Exploring Strategies for Labeling Viruses with Gold Nanoclusters through Non-equilibrium Molecular Dynamics Simulations.
2017
Biocompatible gold nanoclusters can be utilized as contrast agents in virus imaging. The labeling of viruses can be achieved noncovalently but site-specifically by linking the cluster to the hydrophobic pocket of a virus via a lipid-like pocket factor. We have estimated the binding affinities of three different pocket factors of echovirus 1 (EV1) in molecular dynamics simulations combined with non-equilibrium free-energy calculations. We have also studied the effects on binding affinities with a pocket factor linked to the Au102pMBA44 nanocluster in different protonation states. Although the absolute binding affinities are over-estimated for all the systems, the trend is in agreement with r…
Stability of stationary solutions in models of the Calvin cycle
2017
Abstract In this paper results are obtained concerning the number of positive stationary solutions in simple models of the Calvin cycle of photosynthesis and the stability of these solutions. It is proved that there are open sets of parameters in the model of Zhu et al. (2009) for which there exist two positive stationary solutions. There are never more than two isolated positive stationary solutions but under certain explicit special conditions on the parameters there is a whole continuum of positive stationary solutions. It is also shown that in the set of parameter values for which two isolated positive stationary solutions exist there is an open subset where one of the solutions is asym…
Prospects and challenges for computer simulations of monolayer-protected metal clusters
2021
Precise knowledge of chemical composition and atomic structure of functional nanosized systems, such as metal clusters stabilized by an organic molecular layer, allows for detailed computational work to investigate structure-property relations. Here, we discuss selected recent examples of computational work that has advanced understanding of how these clusters work in catalysis, how they interact with biological systems, and how they can make self-assembled, macroscopic materials. A growing challenge is to develop effective new simulation methods that take into account the cluster-environment interactions. These new hybrid methods are likely to contain components from electronic structure t…
A study on time discretization and adaptive mesh refinement methods for the simulation of cancer invasion: The urokinase model
2016
In the present work we investigate a model that describes the chemotactically and proteolytically driven tissue invasion by cancer cells. The model is a system of advection-reaction-diffusion equations that takes into account the role of the serine protease urokinase-type plasminogen activator. The analytical and numerical study of such a system constitutes a challenge due to the merging, emerging, and traveling concentrations that the solutions exhibit. Classical numerical methods applied to this system necessitate very fine discretization grids to resolve these dynamics in an accurate way. To reduce the computational cost without sacrificing the accuracy of the solution, we apply adaptive…
Phase separations induced by a trapping potential in one-dimensional fermionic systems as a source of core-shell structures
2018
Ultracold fermionic gases in optical lattices give a great opportunity for creating different types of novel states. One of them is phase separation induced by a trapping potential between different types of superfluid phases. The core-shell structures, occurring in systems with a trapping potential, are a good example of such separations. The types and the sequences of phases which emerge in such structures can depend on spin-imbalance, shape of the trap and on-site interaction strength. In this work, we investigate the properties of such structures within an attractive Fermi gas loaded in the optical lattice, in the presence of the trapping potential and their relations to the phase diagr…
Transfer Free Energies of Test Proteins Into Crowded Protein Solutions Have Simple Dependence on Crowder Concentration
2019
The effects of macromolecular crowding on the thermodynamic properties of test proteins are determined by the latter's transfer free energies from a dilute solution to a crowded solution. The transfer free energies in turn are determined by effective protein-crowder interactions. When these interactions are modeled at the all-atom level, the transfer free energies may defy simple predictions. Here we investigated the dependence of the transfer free energy (Δμ) on crowder concentration. We represented both the test protein and the crowder proteins atomistically, and used a general interaction potential consisting of hard-core repulsion, non-polar attraction, and solvent-screened electrostati…
Histidine tracts in human transcription factors: insight into metal ion coordination ability
2017
Consecutive histidine repeats are chosen both by nature and by molecular biologists due to their high affinity towards metal ions. Screening of the human genome showed that transcription factors are extremely rich in His tracts. In this work, we examine two of such His-rich regions from forkhead box and MAFA proteins—MB3 (contains 18 His) and MB6 (with 21 His residues), focusing on the affinity and binding modes of Cu2+ and Zn2+ towards the two His-rich regions. In the case of Zn2+ species, the availability of imidazole nitrogen donors enhances metal complex stability. Interestingly, an opposite tendency is observed for Cu2+ complexes at above physiological pH, in which amide nitrogens part…
Author Correction: On the thermodynamic origin of metabolic scaling
2018
The origin and shape of metabolic scaling has been controversial since Kleiber found that basal metabolic rate of animals seemed to vary as a power law of their body mass with exponent 3/4, instead of 2/3, as a surface-to-volume argument predicts. The universality of exponent 3/4 -claimed in terms of the fractal properties of the nutrient network- has recently been challenged according to empirical evidence that observed a wealth of robust exponents deviating from 3/4. Here we present a conceptually simple thermodynamic framework, where the dependence of metabolic rate with body mass emerges from a trade-off between the energy dissipated as heat and the energy efficiently used by the organi…