Search results for "dynamics."

Simple models for nonlinear states of double-helix DNA

2006

Review type introduction is given to the simple modeling of DNA. Intrinsically simple modeling aims at understanding or explaining of some “core” phenomena, not giving any all-embracing model of the underlying system. As a consequence the amount of this type of models and their versions is large. Here we have restricted our contemplation to the most important lines in the path of theoretical understanding of DNA melting or denaturation which is one of the important phases occurring during DNAs replication and transcription processes. The model “line” initiated by Peyrard and Bishop shows the richness these simple models can have.

Phase Equilibria Involved in the Extractive Distillation of Cyclohexane + Cyclohexene Using Diethyl Carbonate as an Entrainer

2011

Isobaric vapor–liquid equilibrium (VLE) data at 100 kPa have been measured for the ternary system cyclohexane + cyclohexene + diethyl carbonate and two constituent binary systems: cyclohexane + diethyl carbonate and cyclohexene + diethyl carbonate. Both binary systems show moderate positive deviations from ideal behavior and do not present an azeotrope. The VLE data have been correlated by the Wilson, universal quasichemical activity coefficient (UNIQUAC), and nonrandom two-liquid (NRTL) equations. The ternary system does not present an azeotrope and is well-estimated from binary interaction parameters. A prediction with the universal functional activity coefficient (UNIFAC)-Dortmund method…

Isobaric Vapor−Liquid Equilibria for Binary and Ternary Mixtures of Ethanol, Methylcyclohexane, and p-Xylene

2004

Consistent vapor−liquid equilibria (VLE) were determined for the ternary system ethanol + methylcyclohexane + p-xylene and the three binary subsystems at 101.3 kPa at temperatures in the range from 345 to 408 K. The binary systems exhibit positive deviation from ideal behavior, and the system ethanol + methylcyclohexane presents a minimum-boiling-point azeotrope. The VLE data have been correlated by the Wilson, NRTL, and UNIQUAC equations. The ternary system does not present an azeotrope and is well predicted from binary interaction parameters.

Density, Speed of Sound, Viscosity, and Excess Properties of Binary Mixtures Formed by Ethanol and Bis(trifluorosulfonyl)imide-Based Ionic Liquids

2015

In this work, viscosities, densities, and speeds of sound of three binary mixtures containing the ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [emim][NTf2], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][NTf2], and 1-hexyl-3-methylimidazo-lium bis(trifluoromethylsulfonyl)imide, [hmim][NTf2], mixed with ethanol were measured at atmospheric pressure in the range of (278.15 to 338.15) K, covering the entire range of compositions. From these experimental data, the excess isentropic compressibility and molar isentropic compressibility of pure components and mixtures have been calculated. Additionally, excess properties, such as viscosity dev…

Comprehensive Organometallic Chemistry. The Synthesis, Reactions and Structures of Organometallic Compounds. Neun Bände. Editors G. Wilkinson, F. G. …

2006

A Theoretical and Experimental Study of Electrochemical pH Control at Gold Interdigitated Microband Arrays

2021

In electroanalysis, solution pH is a critical parameter that often needs to be adjusted and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without additional reagents. FEA simulations have been performed to guide experimental design for both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode array in buffered solution with one comb acting as a protonator, and the other as the sensor.…

Three‐Component Castagnoli‐Cushman Reaction of 3‐Arylglutaconic Acid Anhydrides, Carbonyl Compounds, and Ammonium Acetate: a Quick and Flexible Way t…

2021

1984

By means of data from critical demixing and vapour pressure measurements and by inverse gas chromatography, including the results of published light scattering measurments, a consistent picture is obtained for the entire dependence of the Flory-Huggins parameter χ on the weight fraction w2 of the polymer and on the temperature T for the system tert-butyl acetate/polystyrene. Within the entire T-range (ca. 0°C – 140°C), χ increases stronger than exponentially with w2, the rise being the larger the larger χH (the enthalpy contribution to χ) becomes in the limit of infinite dilution. At sufficiently high temperatures (≳ 50°C), χH changes its sign from negative to positive as w2 is raised. This…

Optimized Continuous Application of Hyperpolarized Xenon to Liquids

2018

International audience; In recent years, NMR with hyperpolarized (HP) xenon inside functionalized host structures (e.g. cryptophanes) have become a potential candidate for the direct observation of metabolic processes (i.e. molecular imaging). A critical issue for real applications is the dissolution of the HP-gas in the liquid which contains the host. In this work, we present recent developments for an improved and controlled dissolution of HP-Xe in liquids using hollow fiber membranes and different compressor systems. The designed apparatus consists of a compressor and a membrane unit. The compressor provides HP-129 Xe continuously at small adjustable pressures and in a polarization-prese…

INVERSE RELATIONSHIPS BETWEEN CHOROIDAL THICKNESS AND RENAL RESISTANCE INDEX IN HYPERTENSIVE PATIENTS

2019

Introduction: Alterations of the renal microcirculation have been documented in animal models of hypertensive renal damage. Traditionally, the retina has been considered the easiest accessible window to study the systemic microcirculation, even though the choroid is the most important vascular layer of the eye. The introduction in the past few years of advanced optical coherence tomography (OCT) techniques has greatly increased our understanding of the choroid. Although the renal resistive index (RRI) was initially considered to reflect intrarenal vascular pathological processes, this index is actually regarded as the result of complex interaction between renal and systemic vascular wall pr…