Dielectric, TSC and Electromechanical Measurements on some Prospective NLO Polymers

1989 ◽  
Vol 175 ◽  
Author(s):  
Paul L. Carr ◽  
Geoff R. Davies ◽  
Ian M. Ward
Keyword(s):  
Relaxation Process ◽  
Applied Field ◽  
Strong Interactions ◽  
Host System ◽  
Poling Process ◽  
Β Relaxation ◽  
The Stability

AbstractThe pyroelectric coefficients of a range of polymers with a methacrylate backbone and nitrostilbene or nitrobipheny mesogens attached by a 3 or 6 carbon spacer have been measured in order to assess the efficiency of the poling process. It is found that the response is much lower than the guest-host system MNA in PMMA, suggesting that the polar mesogens pack anti-parallel and that this alignment is not broken by the applied field.These strong interactions also provide an explanation for the absence of the β relaxation process in the experimental polymers and therefore the brittle nature of the films. They may also explain the stability of the polarisation achieved.

Exo-bonded six-membered heterocycle in the crystal structures of RE7Co2Ge4(RE = La–Nd)

2016 ◽  
Vol 45 (46) ◽  
pp. 18522-18531 ◽  
Author(s):  
Siméon Ponou ◽  
Sven Lidin
Keyword(s):  
Crystal Structures ◽  
Strong Interactions ◽  
The Stability ◽  
Membered Heterocycle

The stability of the heterocyclic {Co4Ge6} clusters in RE7Co2Ge4(RE = La–Nd) is determined by strong interactions with the surrounding RE atoms in the structures.

Invited review: Importance of animal health and welfare for the stability of the three pillars of sustainability of livestock systems

2016 ◽  
Vol 7 (2) ◽  
pp. 208-214
Author(s):  
P. Chemineau
Keyword(s):  
Animal Welfare ◽  
Production Systems ◽  
Animal Health ◽  
Holistic Approach ◽  
Population Increase ◽  
Strong Interactions ◽  
Essential Components ◽  
The Future ◽  
The Stability ◽  
Livestock Systems

The future livestock systems at the world level will have to produce more in the perspective of the population increase in the next 30 years, whereas reducing their environmental footprint and addressing societal concerns. In that perspective, we may wonder if animal health and animal welfare, which are two essential components of production systems, may play an important role in the stability of the three pillars of sustainability of the livestock systems. We already know that objectives driven by economy, environment and society may modify animal welfare and animal health, but is the reverse true? The answer is yes and in 11 cases out of 12 of the matrix health-welfare×3 pillars of sustainability×positive or negative change, we have many examples indicating that animal health and animal welfare are able to modify, positively or negatively, the three pillars of sustainability. Moreover, we also have good examples of strong interactions between health and welfare. These elements play in favour of an holistic approach at the farm level and of a multicriterial definition of what could be the sustainable systems of animal production in the future which will respect animal welfare and maintain a good animal health.

scholarly journals Superconducting edge states in a topological insulator

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
I. V. Yurkevich ◽  
V. Kagalovsky
Keyword(s):  
Topological Insulator ◽  
Time Reversal ◽  
Collective Motion ◽  
Effective Theory ◽  
Strong Interactions ◽  
Time Reversal Symmetry ◽  
Edge States ◽  
Translation Invariant ◽  
Clean System ◽  
The Stability

AbstractWe study the stability of multiple conducting edge states in a topological insulator against perturbations allowed by the time-reversal symmetry. A system is modeled as a multi-channel Luttinger liquid, with the number of channels equal to the number of Kramers doublets at the edge. Assuming strong interactions and weak disorder, we first formulate a low-energy effective theory for a clean translation invariant system and then include the disorder terms allowed by the time-reversal symmetry. In a clean system with N Kramers doublets, N − 1 edge states are gapped by Josephson couplings and the single remaining gapless mode describes collective motion of Cooper pairs synchronous across the channels. Disorder perturbation in this regime, allowed by the time reversal symmetry is a simultaneous backscattering of particles in all N channels. Its relevance depends strongly on the parity if the number of channel N is not very large. Our main result is that disorder becomes irrelevant with the increase of the number of edge modes leading to the stability of the edge states superconducting regime even for repulsive interactions.

Effect of modulation on the onset of thermal convection in a viscoelastic fluid-saturated sparsely packed porous layer

1990 ◽  
Vol 68 (2) ◽  
pp. 214-221 ◽  
Author(s):  
N. Rudraiah ◽  
P. V. Radhadevi ◽  
P. N. Kaloni
Keyword(s):  
Porous Layer ◽  
Viscoelastic Fluid ◽  
Phase Modulation ◽  
Applied Field ◽  
Temperature Modulation ◽  
Elastic Parameters ◽  
Oldroyd Model ◽  
Maximum Range ◽  
Periodic Temperature ◽  
The Stability

The stability of a Boussinesq viscoelastic fluid-saturated horizontal porous layer, when the boundaries of the layer are subjected to periodic temperature modulation, is analyzed. The Darcy–Forchheimer–Brinkman–Oldroyd model is employed and only infinitesimal disturbances are considered. Three cases of the oscillating temperature field were examined: (a) symmetric, so that the wall temperatures are modulated in phase, (b) asymmetric, corresponding to out-of-phase modulation, and (c) only the bottom wall is modulated. Perturbation solution in powers of the amplitude of the applied field is obtained. The effect of the frequency of modulation on the stability is clearly shown. Possibilities of the occurrence of subcritical instabilities are also discussed. It is shown that an increase in the elastic parameters A1 and A2 has a stabilizing influence. An increase in the Prandtl number destabilizes the system for small values of the frequency but stabilizes the systems for large values of the frequency. It is shown that the system is most stable when the boundary temperatures are modulated out of phase. The maximum range of ε when subcritical instabilities exist is also determined.

scholarly journals Dissolution and Interaction of Cellulose Carbamate in NaOH/ZnO Aqueous Solutions

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1092
Author(s):  
Yanhui Kang ◽  
Fangyu Wang ◽  
Zeming Zhang ◽  
Jinping Zhou
Keyword(s):  
Aqueous Solutions ◽  
Strong Interactions ◽  
Hydroxyl Groups ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Cellulose Carbamate ◽  
Lower Temperature ◽  
The Stability

The dissolution and molecular interactions of cellulose carbamate (CC) in NaOH/ZnO aqueous solutions were studied using optical microscopy, differential scanning calorimetry (DSC), 1H NMR, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM), and molecular dynamic simulation. The dissolution of CC in NaOH/ZnO aqueous solutions using the freezing–thawing method was an exothermic process, and the lower temperature was favorable for the dissolution of CC. ZnO dissolved in NaOH aqueous solutions with the formation of Zn(OH)42−, and no free Zn2+ ions existed in the solvents. NaOH/Na2Zn(OH)4 system formed strong interactions with the hydroxyl groups of CC to improve its solubility and the stability of CC solution. The results indicate that 7 wt% NaOH/1.6 wt% ZnO aqueous solution was the most appropriate solvent for the dissolution of CC. This work revealed the dissolution interaction of CC-NaOH/ZnO solutions, which is beneficial for the industrialization of the CarbaCell process.

scholarly journals Adhesion mechanisms of curli subunit CsgA to abiotic surfaces

2016 ◽  
Vol 2 (11) ◽  
pp. e1600998 ◽  
Author(s):  
Elizabeth P. DeBenedictis ◽  
Jenny Liu ◽  
Sinan Keten
Keyword(s):  
Collective Motion ◽  
Point Mutations ◽  
Structural Features ◽  
Strong Interactions ◽  
Surface Attachment ◽  
Silica Surfaces ◽  
Abiotic Surfaces ◽  
Correlated Motion ◽  
Functional Amyloids ◽  
The Stability

Curli fibers are functional amyloids that play a key role in biofilm structure and adhesion to various surfaces. Strong bioinspired adhesives comprising curli fibers have recently been created; however, the mechanisms curli uses to attach onto abiotic surfaces are still uncharacterized. Toward a materials-by-design approach for curli-based adhesives and multifunctional materials, we examine curli subunit adsorption onto graphene and silica surfaces through atomistic simulation. We find that both structural features and sequence influence adhesive strength, enabling the CsgA subunit to adhere strongly to both polar and nonpolar surfaces. Specifically, flexible regions facilitate adhesion to both surfaces, charged and polar residues (Arg, Lys, and Gln) enable strong interactions with silica, and six-carbon aromatic rings (Tyr and Phe) adsorb strongly to graphene. We find that adsorption not only lowers molecular mobility but also leads to loss of secondary structure, factors that must be well balanced for effective surface attachment. Both events appear to propagate through the CsgA structure as correlated motion between clusters of residues, often H-bonded between rows on adjacent β strands. To quantify this, we present a correlation analysis approach to detecting collective motion between residue groups. We find that certain clusters of residues have a higher impact on the stability of the rest of the protein structure, often polar and bulky groups within the helix core. These findings lend insight into bacterial adhesion mechanisms and reveal strategies for theory-driven design of engineered curli fibers that harness point mutations and conjugates for stronger adhesion.

The stability of an interface between viscous fluids subjected to a high-frequency magnetic field and consequences for electromagnetic casting

1995 ◽  
Vol 287 ◽  
pp. 133-150 ◽  
Author(s):  
Deepak ◽  
J. W. Evans
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Applied Field ◽  
Reasonable Assumption ◽  
Inviscid Fluids ◽  
Electromagnetic Casting ◽  
Frequency Magnetic Field ◽  
High Frequency Magnetic Field ◽  
The Stability ◽  
The Magnetic Field

The stability of an interface between inviscid fluids subjected to a high-frequency magnetic field has been examined previously by Garnier & Moreau (1983). The present paper extends that study to include the viscosity of both fluids in order to estimate the damping rates of the perturbations. Furthermore, Garnier & Moreau made an assumption that the frequency of oscillation of the interface could be neglected compared to the frequency of the applied field; they concluded that the applied field was not destabilizing. That (apparently reasonable) assumption has been lifted in the present work and the consequence is that the magnetic field is seen to lead to instability over a significant range of wavelengths. Application of this analysis to the electromagnetic casting of aluminium is discussed.

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