Some Considerations on Confined Water: The Thermal Behavior of Transport Properties in Water-Glycerol and Water-Methanol Mixtures

MRS Advances ◽  
2016 ◽  
Vol 1 (26) ◽  
pp. 1891-1902 ◽  
Author(s):  
Francesco Mallamace ◽  
Carmelo Corsaro ◽  
Domenico Mallamace ◽  
Cirino Vasi ◽  
Sebastiano Vasi ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Molar Fraction ◽  
Relaxation Times ◽  
Confined Water ◽  
Self Diffusion ◽  
Excess Value ◽  
Water Glycerol ◽  
System Properties ◽  
Dynamical Crossover

ABSTRACTWe discuss recent literature data on the relaxation times (the primary tα), viscosity, and self-diffusion in water-glycerol and water-methanol mixtures across a wide temperature range from the stable water phase to the deep supercooled regime (373–147K). In particular, to clarify the role of hydrophilicity interactions (the hydrogen bonds) and hydrophobic interactions we study the mixture in terms of the water molar fraction (XW) with fixed temperatures at 5K steps across the entire composition range, and we find a marked deviation from the ideal thermodynamic behavior of the transport functions. This deviation is strongly T and XW dependent and spans values that range from two orders of magnitude at the highest temperature to more than five in the deeply supercooled regime (more precisely, at ≃200K). We analyze these deviations in terms of how the measured values differ from ideal values and find that the hydrogen-bonding water network dominates system properties up to XW = 0.3. We also examine an Arrhenius plot of the maximum excess value (Δtα(T) vs. 1/T) and find two significant changes due to water: one at the dynamical crossover temperature (TL ≃ 225K, i.e., the locus of the Widom line), and one at T ≃ 315K (the water isothermal compressibility χT minimum).

scholarly journals Hydrophilic and Hydrophobic Effects on the Structure and Themodynamic Properties of Confined Water: Water in Solutions

2021 ◽  
Vol 22 (14) ◽  
pp. 7547
Author(s):  
Francesco Mallamace ◽  
Domenico Mallamace ◽  
Sow-Hsin Chen ◽  
Paola Lanzafame ◽  
Georgia Papanikolaou
Keyword(s):  
Liquid Water ◽  
Hydrophobic Interactions ◽  
Relaxation Times ◽  
Configurational Entropy ◽  
Local Order ◽  
Pure Liquid ◽  
Confined Water ◽  
Hydrophobic Effects ◽  
Hydrogen Bond Interactions ◽  
The Times

NMR spectroscopy is used in the temperature range 180–350 K to study the local order and transport properties of pure liquid water (bulk and confined) and its solutions with glycerol and methanol at different molar fractions. We focused our interest on the hydrophobic effects (HE), i.e., the competition between hydrophilic and hydrophobic interactions. Nowadays, compared to hydrophilicity, little is known about hydrophobicity. Therefore, the main purpose of this study is to gain new information about hydrophobicity. As the liquid water properties are dominated by polymorphism (two coexisting liquid phases of high and low density) due to hydrogen bond interactions (HB), creating (especially in the supercooled regime) the tetrahedral networking, we focused our interest to the HE of these structures. We measured the relaxation times (T1 and T2) and the self-diffusion (DS). From these times, we took advantage of the NMR property to follow the behaviors of each molecular component (the hydrophilic and hydrophobic groups) separately. In contrast, DS is studied in terms of the Adam–Gibbs model by obtaining the configurational entropy (Sconf) and the specific heat contributions (CP,conf). We find that, for the HE, all of the studied quantities behave differently. For water–glycerol, the HB interaction is dominant for all conditions; water–methanol, two different T-regions above and below 265 K are observable, dominated by hydrophobicity and hydrophilicity, respectively. Below this temperature, where the LDL phase and the HB network develops and grows, with the times and CP,conf change behaviors leading to maxima and minima. Above it, the HB becomes weak and less stable, the HDL dominates, and hydrophobicity determines the solution.

Diffusion Mechanisms in Sige Alloys

1999 ◽  
Vol 568 ◽  
Author(s):  
Arthur F.W. Willoughby ◽  
Janet M. Bonar ◽  
Andrew D.N. Paine
Keyword(s):  
Diffusion Processes ◽  
Dopant Diffusion ◽  
Elemental Silicon ◽  
Self Diffusion ◽  
Si Substrates ◽  
Marker Layer ◽  
Diffusion Mechanisms ◽  
Silicon And Germanium ◽  
Charged Defects

ABSTRACTInterest in diffusion processes in SiGe alloys arises from their potential in HBT's, HFET's, and optoelectronics devices, where migration over distances as small as a few nanometres can be significant. Successful modelling of these processes requires a much improved understanding of the mechanisms of self- and dopant diffusion in the alloy, although recent progress has been made. It is the purpose of this review to set this in the context of diffusion processes in elemental silicon and germanium, and to identify how this can help to elucidate behaviour in the alloy. Firstly, self diffusion processes are reviewed, from general agreement that self-diffusion in germanium is dominated by neutral and acceptor vacancies, to the position in silicon which is still uncertain. Germanium diffusion in silicon, however, appears to be via both vacancy and interstitial processes, and in the bulk alloy there is evidence for a change in dominant mechanism at around 35 percent germanium. Next, a review of dopant diffusion begins with Sb, which appears to diffuse in germanium by a mechanism similar to self-diffusion, and in silicon via monovacancies also, from marker layer evidence. In SiGe, the effects of composition and strain in epitaxial layers on Si substrates are also consistent with diffusion via vacancies, but questions still remain on the role of charged defects. The use of Sb to monitor vacancy effects such as grown-in defects by low temperature MBE, are discussed. Lastly, progress in assessing the role of vacancies and interstitials in the diffusion of boron is reviewed, which is dominated by interstitials in silicon-rich alloys, but appears to change to domination by vacancies at around 40 percent germanium, although studies in pure germanium are greatly needed.

The role of hydrophobic interactions in binding of polyamines to non NMDA receptor ion channels

1998 ◽  
Vol 37 (10-11) ◽  
pp. 1381-1391 ◽  
Author(s):  
Changhai Cu ◽  
Robert Bähring ◽  
Mark L. Mayer
Keyword(s):  
Ion Channels ◽  
Nmda Receptor ◽  
Hydrophobic Interactions

scholarly journals Analysis of Healthcare Systems by Using Systemic Approach

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Andrzej Bielecki ◽  
Sylwia Nieszporska
Keyword(s):  
Systems Theory ◽  
Organizational Innovation ◽  
Autonomous Systems ◽  
National Level ◽  
Healthcare Systems ◽  
Systemic Approach ◽  
Public Organization ◽  
National Healthcare ◽  
System Properties

National healthcare systems in all countries do not act effectively. Therefore, especially strategies for introducing organizational innovation to public organization should be considered. The problem is how to organize the research in this field. One of the generally accepted solutions is the systemic approach to healthcare systems. In this paper multiagent systems theory and autonomous systems theory are applied to the analysis of main types of healthcare systems. Such analysis allows us to consider the system properties: the level of the autonomy, energy dissipation in the system, the payoff specificity (in the meaning of game theory), functional role of the agents in the system, the level of the agents’ cooperation, and delays in flows of money, requests, rules, and controls. As a result, some new functionalities of the healthcare system on the national level have been found and analysed. The aforementioned parameters are good tools to analyse the system functionality.

Role of Hydrophobic Interactions in Enzyme Inhibition by Drugs

1970 ◽  
Vol 59 (6) ◽  
pp. 865-868 ◽  
Author(s):  
Eric J. Lien ◽  
Mehdi Hussain ◽  
George L. Tong
Keyword(s):  
Enzyme Inhibition ◽  
Hydrophobic Interactions

Self Diffusion in SiC: the Role of Intrinsic Point Defects

2001 ◽  
Vol 353-356 ◽  
pp. 323-326 ◽  
Author(s):  
Alexander Mattausch ◽  
M. Bockstedte ◽  
Oleg Pankratov
Keyword(s):  
Point Defects ◽  
Intrinsic Point Defects ◽  
Self Diffusion

On the role of nano-confined water at the 2D/SiO2 interface in layer number engineering of exfoliated MoS2 via thermal annealing

2D Materials ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 025001 ◽  
Author(s):  
S Palleschi ◽  
G D’Olimpio ◽  
P Benassi ◽  
M Nardone ◽  
R Alfonsetti ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Confined Water ◽  
Layer Number
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