Force Field Benchmark of the TraPPE_UA for Polar Liquids: Density, Heat of Vaporization, Dielectric Constant, Surface Tension, Volumetric Expansion Coefficient, and Isothermal Compressibility

2018 ◽  
Vol 122 (5) ◽  
pp. 1669-1678 ◽  
Author(s):  
Edgar Núñez-Rojas ◽  
Jorge Alberto Aguilar-Pineda ◽  
Alexander Pérez de la Luz ◽  
Edith Nadir de Jesús González ◽  
José Alejandre
Keyword(s):  
Surface Tension ◽  
Dielectric Constant ◽  
Force Field ◽  
Expansion Coefficient ◽  
Isothermal Compressibility ◽  
Polar Liquids ◽  
Heat Of Vaporization ◽  
Volumetric Expansion ◽  
Volumetric Expansion Coefficient

scholarly journals Thermal Transitions of Cocoa Butter: A Novel Characterization Method by Temperature Modulation

Foods ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 449 ◽  
Author(s):  
Julia Rocha Gouveia ◽  
Kelly Cristina de Lira Lixandrão ◽  
Lara Basílio Tavares ◽  
Paulo Henrique Lixandrão Fernando ◽  
Guilherme Elias Saltarelli Garcia ◽  
...  
Keyword(s):  
Cocoa Butter ◽  
Expansion Coefficient ◽  
Standard Technique ◽  
Temperature Modulation ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Volumetric Expansion ◽  
New Information ◽  
Temperature Ramps ◽  
Volumetric Expansion Coefficient

For the first time, the novel experimental technique Temperature Modulated Optical Refractometry (TMOR) was employed for cocoa butter thermal transitions characterization. The average refractive index (NMEAN), the volume (v) change, and the volumetric expansion coefficient ( β q ) as well as the dynamic quantities β ′ and β ″ (real and imaginary volumetric expansion coefficient, respectively) were monitored during cooling and heating and compared to the heat flow curves obtained via the standard technique dynamic scanning calorimetry (DSC). The investigation of these quantities showed that TMOR analysis can yield not only thermal transitions temperatures that are comparable to DSC results, but also some new thermal events that are not detected by DSC. This outcome suggests that TMOR might provide some additional insights on cocoa butter melting and crystallization by means of frequency-dependent measurements due to temperature modulation. This new information that can be accessed during temperature ramps might provide a deeper insight into thermal behavior of fat-based foods, evidencing TMOR value as a tool for thermal transitions investigation.

scholarly journals DETERMINATION OF THE VOLUMETRIC EXPANSION COEFFICIENT OF PINEAPPLE AND WATERMELON PULPS

2021 ◽  
pp. 32-44
Author(s):  
Sérgio Luís Melo Viroli ◽  
Fernando Morais Rodrigues ◽  
Paula Jucá de Sousa ◽  
Paulo Vitoriano Dantas Pereira ◽  
Fernando de Paula e Silva ◽  
...  
Keyword(s):  
Expansion Coefficient ◽  
Volumetric Expansion ◽  
Volumetric Expansion Coefficient

scholarly journals Improving 1-propanol Force Field: a New Methodology

2021 ◽  
Author(s):  
José Abundio Daniel Alva-Tamayo ◽  
Iván Guillén-Escamilla ◽  
Gloria Arlette Méndez-Maldonado ◽  
José Guillermo Méndez-Bermúdez
Keyword(s):  
Surface Tension ◽  
Dielectric Constant ◽  
Diffusion Coefficient ◽  
Force Field ◽  
Bond Distance ◽  
Experimental Spectrum ◽  
Static Structure ◽  
Self Diffusion ◽  
Structure Factors ◽  
Self Diffusion Coefficient

Abstract A new force field for 1-propanol, in the united and all atom models, has been obtained by combining two different empirical methodologies. The first was developed by scaling atom charges, and Lennard-Jones parameters to fit the dielectric constant, surface tension, and density ((2018) J. Chem. Theory Comput. 14:5949-5958). The second methodology consists of moving these parameters and together with the bond distance to obtain the liquid-vapor phase diagram of the CO2 molecule ((1995) J. Phys. Chem. 99:12021-12024). The last methodology is used to obtain the self-diffusion coefficient, which was not considered in the first one. With this new methodology, the experimental density, dielectric constant, surface tension, and self-diffusion coefficient at ambient temperature could be achieved. Furthermore, we show the temperature dependence of the aforementioned properties. The static structure factors are in accordance with the experimental spectrum. Solubility is increased to the experimental value for the united atom model after applying this methodology and for all atom scheme, the experimental solubility value is maintained.

Electrohydrodynamic stability: Taylor–Melcher theory for a liquid bridge suspended in a dielectric gas

2002 ◽  
Vol 452 ◽  
pp. 163-187 ◽  
Author(s):  
C. L. BURCHAM ◽  
D. A. SAVILLE
Keyword(s):  
Surface Tension ◽  
Dielectric Constant ◽  
Electric Fields ◽  
Liquid Bridge ◽  
Numerical Solutions ◽  
Specific Conductivity ◽  
Axisymmetric Deformation ◽  
Aspect Ratios ◽  
The Stability ◽  
Theory And Experiment

A liquid bridge is a column of liquid, pinned at each end. Here we analyse the stability of a bridge pinned between planar electrodes held at different potentials and surrounded by a non-conducting, dielectric gas. In the absence of electric fields, surface tension destabilizes bridges with aspect ratios (length/diameter) greater than π. Here we describe how electrical forces counteract surface tension, using a linearized model. When the liquid is treated as an Ohmic conductor, the specific conductivity level is irrelevant and only the dielectric properties of the bridge and the surrounding gas are involved. Fourier series and a biharmonic, biorthogonal set of Papkovich–Fadle functions are used to formulate an eigenvalue problem. Numerical solutions disclose that the most unstable axisymmetric deformation is antisymmetric with respect to the bridge’s midplane. It is shown that whilst a bridge whose length exceeds its circumference may be unstable, a sufficiently strong axial field provides stability if the dielectric constant of the bridge exceeds that of the surrounding fluid. Conversely, a field destabilizes a bridge whose dielectric constant is lower than that of its surroundings, even when its aspect ratio is less than π. Bridge behaviour is sensitive to the presence of conduction along the surface and much higher fields are required for stability when surface transport is present. The theoretical results are compared with experimental work (Burcham & Saville 2000) that demonstrated how a field stabilizes an otherwise unstable configuration. According to the experiments, the bridge undergoes two asymmetric transitions (cylinder-to-amphora and pinch-off) as the field is reduced. Agreement between theory and experiment for the field strength at the pinch-off transition is excellent, but less so for the change from cylinder to amphora. Using surface conductivity as an adjustable parameter brings theory and experiment into agreement.

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