scholarly journals Some Remarks on Colloid Stability: Selected Examples Taken from the Milk Chain for Food Prepares

2020 ◽  
Author(s):  
Camillo La Mesa ◽  
Gianfranco Risuleo
Keyword(s):  
Phase Separation ◽  
Double Layer ◽  
Van Der Waals ◽  
Worked Examples ◽  
Dlvo Theory ◽  
Decay Length ◽  
Colloid Stability ◽  
Stabilization Phase ◽  
The Stability ◽  
Repulsive Forces

Different forces play a key-role in the stability of food colloid dispersions. Focus is here on those controlling attraction and/or repulsion, which concur to stabilization, phase separation, coagulation, and are quite evident in water-based systems. Combination of attractive and repulsive forces favors, or hinders, the association of colloid entities; such processes are often met in food technology. The above processes depend on the forces at work, and on colloid concentration in the medium (i.e. on inter-particle distance). Worked examples deals with milk manipulation procedures, ending in cheese formation. The whole milk-working sequence is controlled by the combination of forces leading to aggregation and phase separation of casein and other milk components. Thereafter, one gets either fresh, for prompt consumption, or aged cheeses. The combination of attractive (van der Waals, vdW, and depletion) with repulsive (double layer, DL, but also with steric) forces results in the dominance of aggregation versus dispersion modes in all steps of milk transformation, which depend on the distance among colloid particles, on the amplitude of the mentioned forces, and on their decay length. The combined role of double layer and van der Waals (vdW) forces is at the basis of the DLVO theory on colloid stability, which is properly modified when these forces overlap with steric stabilization and, eventually, with depletion. Steric effects are dispersive, depletion ones favor colloid nucleation in a single phase. The milk manipulation chain is a worked example of the intriguing association features controlled by the mentioned forces (and of ancillary ones, as well), and indicates which forces favor the formation of products such as Parmesan or Mozzarella cheese, but are not alien to the preparation of many other dairy products.

scholarly journals Some Remarks on Colloid Stability: Selected Examples Taken from the Milk Chain for Food Prepares

2020 ◽  
Vol 4 (4) ◽  
pp. 58
Author(s):  
Camillo La Mesa ◽  
Gianfranco Risuleo
Keyword(s):  
Phase Separation ◽  
Double Layer ◽  
Van Der Waals ◽  
Interparticle Distance ◽  
Worked Examples ◽  
Dlvo Theory ◽  
Colloid Stability ◽  
Stabilization Phase ◽  
The Stability ◽  
Repulsive Forces

Different forces play key roles in the stability of food colloid dispersions. The focus here is on those controlling attraction and/or repulsion, which concur to stabilization, phase separation, coagulation and are quite evident in water-based systems. The combination of attractive and repulsive forces favors or hinders the association of colloid entities; such processes are often met in food technology. The above processes depend on the forces at work and colloid concentration in the medium (i.e., on interparticle distance). Worked examples deal with milk manipulation procedures, ending in cheese formation. The whole milk sequence is controlled by the combination of forces leading to aggregation and phase separation of casein and other milk components. Thereafter, one gets either fresh, for prompt consumption, or aged cheeses. The combination of attractive (van der Waals, vdW, and depletion) with repulsive (double layer, DL, but also steric) forces results in the dominance of aggregation versus dispersion modes in the milk transformation chain, which depends on the distance among colloid particles, on the amplitude of the mentioned forces, and on their decay. The combined role of double layer and van der Waals (vdW) forces is at the basis of the DLVO theory on colloid stability, which is properly modified when these forces overlap with steric stabilization and, eventually, with depletion. Steric effects are dispersive, and depletion ones favor colloid nucleation in a single phase. The milk manipulation chain is a worked example of the intriguing association features controlled by the mentioned forces (and of ancillary ones, as well), and indicates which forces favor the formation of products such as parmesan or mozzarella cheese but are not alien to the preparation of many other dairy products.

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

Concisely modularized assembling of graphene-based thin films with promising electrode performance

2019 ◽  
Vol 3 (7) ◽  
pp. 1462-1470 ◽  
Author(s):  
Weiwei Wei ◽  
Rohit L. Vekariy ◽  
Chuanting You ◽  
Yafei He ◽  
Ping Liu ◽  
...  
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Double Layer ◽  
Van Der Waals ◽  
Cellulose Nanofibers ◽  
Van Der Waals Interactions ◽  
Electrode Performance ◽  
Reduced Graphene

Highly dense thin films assembled from cellulose nanofibers and reduced graphene oxide via van der Waals interactions to realize ultrahigh volumetric double-layer capacitances.

scholarly journals Artificial synapses with a sponge-like double-layer porous oxide memristor

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Qin Gao ◽  
Anping Huang ◽  
Jing Zhang ◽  
Yuhang Ji ◽  
Jingjing Zhang ◽  
...  
Keyword(s):  
Double Layer ◽  
Layer Structure ◽  
Learning Experience ◽  
Rapid Development ◽  
Spike Timing ◽  
Synaptic Functions ◽  
Intelligence Studies ◽  
Bionic Structure ◽  
Porous Oxide ◽  
The Stability

AbstractClosely following the rapid development of artificial intelligence, studies of the human brain and neurobiology are focusing on the biological mechanisms of neurons and synapses. Herein, a memory system employing a nanoporous double-layer structure for simulation of synaptic functions is described. The sponge-like double-layer porous (SLDLP) oxide stack of Pt/porous LiCoO2/porous SiO2/Si is designed as presynaptic and postsynaptic membranes. This bionic structure exhibits high ON–OFF ratios up to 108 during the stability test, and data can be maintained for 105 s despite a small read voltage of 0.5 V. Typical synaptic functions, such as nonlinear transmission characteristics, spike-timing-dependent plasticity, and learning-experience behaviors, are achieved simultaneously with this device. Based on the hydrodynamic transport mechanism of water molecules in porous sponges and the principle of water storage, the synaptic behavior of the device is discussed. The SLDLP oxide memristor is very promising due to its excellent synaptic performance and potential in neuromorphic computing.

Isotope effects on the stability of the nitrogen—acetylene van der Waals dimer

1993 ◽  
Vol 171 (1-2) ◽  
pp. 89-95 ◽  
Author(s):  
Sean A.C. McDowell ◽  
A. David Buckingham
Keyword(s):  
Isotope Effects ◽  
Van Der Waals ◽  
The Stability ◽  
Van Der Waals Dimer

scholarly journals Communication: On the Stability and Necessary Electrophoretic Mobility of Bare Oil Nanodroplets in Water

2020 ◽  
Author(s):  
Saranya Pullanchery ◽  
Sergey Kulik ◽  
halil okur ◽  
Hilton. B. de Aguiar ◽  
Sylvie Roke
Keyword(s):  
Electrophoretic Mobility ◽  
Dlvo Theory ◽  
Air Bubbles ◽  
Oil Droplets ◽  
Cleaning Procedure ◽  
Charged Droplets ◽  
Oil In Water ◽  
The Creation ◽  
The Stability ◽  
The 19Th Century

Hydrophobic oil droplets, particles and air bubbles can be dispersed in water as kinetically stabilized dispersions. It has been established since the 19th century that such objects harbor a negative electrostatic potential roughly twice larger than the thermal energy. The source of this charge continues to be one of the core observations in relation to hydrophobicity and its molecular explanation is still debated. What is clear though, is that the stabilizing interaction in these systems is understood in terms of electrostatic repulsion via DLVO theory. Recent work [Carpenter et al., PNAS 116 (2019) 9214] has added another element into the discussion, reporting the creation of bare near-zero charged droplets of oil in water that are stable for several days. Key to the creation of the droplets is a rigorous glassware cleaning procedure. Here, we investigate these conclusions and show that the cleaning procedure of glassware has no influence on the electrophoretic mobility of the droplets, that oil droplets with near-zero charge are unstable, and provide an alternative possible explanation for the observations involving glass surface chemistry.

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