Surface tension and surface entropy of superfluidHe4

1977 ◽  
Vol 16 (5) ◽  
pp. 1944-1953 ◽  
Author(s):  
J. R. Eckardt ◽  
D. O. Edwards ◽  
S. Y. Shen ◽  
F. M. Gasparini
Keyword(s):  
Surface Tension ◽  
Surface Entropy

scholarly journals Surface Thermodynamics, Viscosity, Activation Energy of N-Methyldiethanolamine Aqueous Solutions Promoted by Tetramethylammonium Arginate

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1337
Author(s):  
Xiangfeng Tian ◽  
Lemeng Wang ◽  
Pan Zhang ◽  
Dong Fu
Keyword(s):  
Activation Energy ◽  
Surface Tension ◽  
Diffusion Coefficient ◽  
Aqueous Solutions ◽  
Quantitative Relationship ◽  
Viscosity Data ◽  
Surface Thermodynamics ◽  
Surface Entropy ◽  
Operation Conditions ◽  
Surface Enthalpy

The surface tension and viscosity values of N-methyldiethanolamine (MDEA) aqueous solutions promoted by tetramethylammonium arginate ([N1111][Arg]) were measured and modeled. The experimental temperatures were 303.2 to 323.2 K. The mass fractions of MDEA (wMDEA) and [N1111][Arg] (w[N1111][Arg]) were 0.300 to 0.500 and 0.025 to 0.075, respectively. The measured surface tension and viscosity values were satisfactorily fitted to thermodynamic models. With the aid of experimentally viscosity data, the activation energy (Ea) and H2S diffusion coefficient (DH2S) of MDEA-[N1111][Arg] aqueous solution were deduced. The surface entropy and surface enthalpy of the solutions were calculated using the fitted model of the surface tension. The quantitative relationship between the calculated values (surface tension, surface entropy, surface enthalpy, viscosity, activation energy, and H2S diffusion coefficient) and the operation conditions (mass fraction and temperature) was demonstrated.

scholarly journals Surface tension and density of Fe – Mn melts

2020 ◽  
Vol 63 (1) ◽  
pp. 40-46
Author(s):  
N. I. Sinitsin ◽  
O. A. Chikova ◽  
V. V. V’yukhin
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Sessile Drop ◽  
Entropy Change ◽  
Surface Tension Coefficient ◽  
Cooling Mode ◽  
Linear Character ◽  
Surface Entropy ◽  
Concentration Dependences ◽  
Mn Content

The article presents original experimental data on surface tension of the melts Fe100 – x Mnx (x = 4 ... 13 wt. %). Surface tension and density of the melt was measured by the method of sessile drop at heating from the liquidus temperature up to 1780 °C and subsequent cooling of the sample in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe – Mn melts was constructed. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe – Mn melts decreases while Mn content increases. Experimental data on the surface tension of Fe – Mn melts is consistent with the theoretical dependences (Pavlova-Popiel equation and the Shishkovsky equation). During the study of microheterogeneity of Fe – Mn melts, correlation between the values of kinematic viscosity, surface tension and density was determined. Dependence of the fluidity of Fe – Mn melts on their density in the cooling mode has a linear character which indicates the implementation of the Bachinsky law. Discrepancy of values of the ratio of melt viscosity to the surface tension coefficient was obtained from experimental data and was calculated by the empirical formula. According to the experimental data on viscosity and surface tension of Fe – Mn melts, the authors have evaluated the entropy change in volume of the melt and change of surface entropy of the melt, respectively. Surface entropy of the melt and entropy in the melt volume decreases in absolute value with increase of Mn content in it. According to the results of the work, it was concluded that there is no destruction of the microheterogeneous structure of Fe100 – x Mnx melts (x = 4 ... 13 wt. %) when heated up to 1780 °С.

scholarly journals Surface tension and density of Fe – Mn melts

2020 ◽  
Vol 63 (1) ◽  
pp. 40-46
Author(s):  
N. I. Sinitsin ◽  
O. A. Chikova ◽  
V. V. V’yukhin
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Sessile Drop ◽  
Entropy Change ◽  
Surface Tension Coefficient ◽  
Cooling Mode ◽  
Linear Character ◽  
Surface Entropy ◽  
Concentration Dependences ◽  
Mn Content

The article presents original experimental data on surface tension of the melts Fe100 – x Mnx (x = 4 ... 13 wt. %). Surface tension and density of the melt was measured by the method of sessile drop at heating from the liquidus temperature up to 1780 °C and subsequent cooling of the sample in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe – Mn melts was constructed. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe – Mn melts decreases while Mn content increases. Experimental data on the surface tension of Fe – Mn melts is consistent with the theoretical dependences (Pavlova-Popiel equation and the Shishkovsky equation). During the study of microheterogeneity of Fe – Mn melts, correlation between the values of kinematic viscosity, surface tension and density was determined. Dependence of the fluidity of Fe – Mn melts on their density in the cooling mode has a linear character which indicates the implementation of the Bachinsky law. Discrepancy of values of the ratio of melt viscosity to the surface tension coefficient was obtained from experimental data and was calculated by the empirical formula. According to the experimental data on viscosity and surface tension of Fe – Mn melts, the authors have evaluated the entropy change in volume of the melt and change of surface entropy of the melt, respectively. Surface entropy of the melt and entropy in the melt volume decreases in absolute value with increase of Mn content in it. According to the results of the work, it was concluded that there is no destruction of the microheterogeneous structure of Fe100 – x Mnx melts (x = 4 ... 13 wt. %) when heated up to 1780 °С.

scholarly journals Molecular Dynamics Simulation of the Surface Tension of Aqueous Sodium Chloride: from Dilute to Highly Supersaturated Solutions and Molten Salt

2017 ◽  
Author(s):  
Xiaoxiang Wang ◽  
Chuchu Chen ◽  
Kurt Binder ◽  
Uwe Kuhn ◽  
Ulrich Pöschl ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Sodium Chloride ◽  
Concentration Dependence ◽  
Inflection Point ◽  
Dynamics Simulation ◽  
Nacl Solution ◽  
Surface Entropy ◽  
Surface Enthalpy ◽  
Supersaturated Solutions

Abstract. Sodium chloride (NaCl) is one of the key components of atmospheric aerosols. The surface tension of aqueous NaCl solution (σNaCl,sol) and its concentration dependence are essential to determine the equilibrium water vapor pressure of aqueous NaCl droplets. Supersaturated NaCl solution droplets are observed in laboratory experiments and under atmospheric conditions, but the experimental data for σNaCl,sol are mostly limited up to sub-saturated solutions. In this study, the surface tension of aqueous NaCl is investigated by molecular dynamics (MD) simulations and pressure tensor method from dilute to highly supersaturated solutions. We show that the linear approximation of concentration dependence of σNaCl,sol at molality scale can be extended to the supersaturated NaCl solution until a molality of ~9.6 mol kg−1 (i.e., solute mass fraction (xNaCl) of ~0.36). Energetic analyses show that this monotonic increase of surface tension is driven by the increase of excessive surface enthalpy (∆H) as the solution becomes concentrated. After that, the simulated σNaCl,sol remains almost unchanged until xNaCl of ~0.47 (near the concentration upon efflorescence). The existence of the inflection point at xNaCl of ~0.36 and the stable surface tension of xNaCl between ~0.36 and ~0.47 can be attributed to a competitive growth of excessive surface entropy term (T · ∆S) and the excessive surface enthalpy term (∆H). After a second inflection point at xNaCl of ~0.47, the simulated σNaCl,sol gradually regains the growing momentum with a tendency to approach the surface tension of molten NaCl (~148.4 mN m−1 at 298.15 K, MD simulation based extrapolation). This fast increase of σNaCl,sol at xNaCl > 0.47 is primarily still an excessive surface enthalpy-driving process, although contribution from concurrent fluctuation of excessive surface entropy is expected but in a relatively smaller scale. Our results reveal different regimes of concentration dependence of the surface tension of aqueous NaCl at 298.15 K: a water-dominated regime (xNaCl from 0 to ~0.36), a transition regime (xNaCl from ~0.36 to ~0.47) and a molten NaCl-dominated regime (xNaCl from ~0.47 to 1).

scholarly journals Molecular dynamics simulation of the surface tension of aqueous sodium chloride: from dilute to highly supersaturated solutions and molten salt

2018 ◽  
Vol 18 (23) ◽  
pp. 17077-17086 ◽  
Author(s):  
Xiaoxiang Wang ◽  
Chuchu Chen ◽  
Kurt Binder ◽  
Uwe Kuhn ◽  
Ulrich Pöschl ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Sodium Chloride ◽  
Concentration Dependence ◽  
Inflection Point ◽  
Nacl Solution ◽  
Surface Entropy ◽  
Excess Surface ◽  
Surface Enthalpy ◽  
Supersaturated Solutions

Abstract. Sodium chloride (NaCl) is one of the key components of atmospheric aerosols. The surface tension of aqueous NaCl solution (σNaCl,sol) and its concentration dependence are essential to determine the equilibrium water vapor pressure of aqueous NaCl droplets. Supersaturated NaCl solution droplets are observed in laboratory experiments and under atmospheric conditions, but the experimental data for σNaCl,sol are mostly limited up to subsaturated solutions. In this study, the surface tension of aqueous NaCl is investigated by molecular dynamics (MD) simulations and the pressure tensor method from dilute to highly supersaturated solutions. We show that the linear approximation of concentration dependence of σNaCl,sol at molality scale can be extended to the supersaturated NaCl solution until a molality of ∼10.7 mol kg−1 (i.e., solute mass fraction (xNaCl) of ∼0.39). Energetic analyses show that this monotonic increase in surface tension is driven by the increase in excess surface enthalpy (ΔH) as the solution becomes concentrated. After that, the simulated σNaCl,sol remains almost unchanged until xNaCl of ∼0.47 (near the concentration upon efflorescence). The existence of the “inflection point” at xNaCl of ∼0.39 and the stable surface tension of xNaCl between ∼0.39 and ∼0.47 can be attributed to the nearly unchanged excess surface entropy term (T⋅ΔS) and the excess surface enthalpy term (ΔH). After a “second inflection point” at xNaCl of ∼0.47, the simulated σNaCl,sol gradually regains the growing momentum with a tendency to approach the surface tension of molten NaCl (∼175.58 mN m−1 at 298.15 K, MD simulation-based extrapolation). This fast increase in σNaCl,sol at xNaCl>0.47 is a process driven by excess surface enthalpy and excess surface entropy. Our results reveal different regimes of concentration dependence of the surface tension of aqueous NaCl at 298.15 K: a water-dominated regime (xNaCl from 0 to ∼0.39), a transition regime (xNaCl from ∼0.39 to ∼0.47) and a molten NaCl-dominated regime (xNaCl from ∼0.47 to 1).

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

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