Suppression of metachromasia of galactogen by organic solvents and its relation to their dielectric constants

Histochemie ◽  
1972 ◽  
Vol 30 (4) ◽  
pp. 367-370 ◽  
Author(s):  
A. T. Varute ◽  
S. G. Nanaware
Keyword(s):  
Organic Solvents ◽  
Dielectric Constants

Organo-Soluble, Segmented Rigid-Rod Polyimides: Synthesis and Properties

1991 ◽  
Vol 227 ◽  
Author(s):  
F. W. Harris ◽  
S. L. C. Hsu ◽  
C. J. Lee ◽  
B. S. Lee ◽  
F. Arnold ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Oxidative Stability ◽  
Organic Solvents ◽  
Dielectric Constants ◽  
Glass Transition Temperatures ◽  
Thermal Expansion Coefficients ◽  
Rigid Rod ◽  
Expansion Coefficients

ABSTRACTSeveral segmented, rigid-rod polyimides have been prepared that are soluble in organic solvents in their fully imidized form. The polymers were prepared from commercial dianhydrides and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB). Their intrinsic viscosities ranged from 1.0 to 4.9 dL/g. Tough, colorless films could be cast from m-cresol solutions at 100°C. The polymers had glass transition temperatures (Tgs) above 275°C and displayed outstanding thermal and thermo-oxidative stability. Fibers were prepared from the 3,3′,4,4′-tetracarboxybiphenyl dianhydride (BPDA) based polymers that had moduli of 130 GPa and tensile strengths of 3.2 GPa. The thermal expansion coefficients and dielectric constants of thin films (20–25 μm) of the polymers were as low as −2.40×10−6 and 2.5, respectively.

Dissociation of C6F5SO3Li in two organic solvents with different dielectric constants: a Raman spectroscopic study

2007 ◽  
Vol 38 (12) ◽  
pp. 1570-1576 ◽  
Author(s):  
G. Hirankumar ◽  
C. Iojoiu ◽  
F. Alloin ◽  
J. Y. Sanchez ◽  
T. Pagnier
Keyword(s):  
Spectroscopic Study ◽  
Organic Solvents ◽  
Dielectric Constants ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study

Solvent dependent intramolecular excimer emission of di(1-pyrenyl)silane and di(1-pyrenyl)methane derivatives

RSC Advances ◽  
2015 ◽  
Vol 5 (8) ◽  
pp. 5846-5849 ◽  
Author(s):  
Shin-ichi Kondo ◽  
Yuka Taguchi ◽  
Yi Bie
Keyword(s):  
Organic Solvents ◽  
Dielectric Constants ◽  
Excimer Emission ◽  
Polar Organic Solvents ◽  
Intramolecular Excimer

Di(1-pyrenyl)silane and methane derivatives showed unprecedented intramolecular excimer emission in polar organic solvents such as DMSO and the ratio of excimer/monomer emissions strongly depends on the dielectric constants of the solvents.

scholarly journals Characteristics of nearly dry enzymes in organic solvents: implications for biocatalysis in the absence of water

2004 ◽  
Vol 359 (1448) ◽  
pp. 1299-1307 ◽  
Author(s):  
Douglas S. Clark
Keyword(s):  
Organic Solvents ◽  
Protein Interactions ◽  
Active Site ◽  
Enzymatic Reaction ◽  
Solvent Polarity ◽  
Kinetic Studies ◽  
Immobilized Enzymes ◽  
Dielectric Constants ◽  
Electrostatic Model ◽  
Wide Range

We have examined enzymes in nearly anhydrous organic solvents spanning a wide range of dielectric constants using a combination of electron paramagnetic resonance (EPR) spectroscopy, molecular dynamics simulations, high–pressure kinetic studies and the electrostatic model of Kirkwood. This approach enabled us to investigate the relationship between catalytic activity, protein flexibility and solvent polarity for an enzymatic reaction proceeding through a highly polar transition state in the near absence of water. Further insights into water–protein interactions and the involvement of water in enzyme structure and function have been obtained by EPR and multinuclear nuclear magnetic resonance studies of enzymes suspended and immobilized in organic solvents with and without added water. In these systems, correlations were observed between the water content and enzyme activity, flexibility, and active–site polarity, although the structural properties of suspended and immobilized enzymes differed markedly. These results have helped to elucidate the role of water in molecular events at the enzymic active site leading to improved biocatalysis in low–water environments.

Electron microscopy studies of PZT ferroelectric film capacitor structures

1992 ◽  
Vol 50 (2) ◽  
pp. 1364-1365
Author(s):  
V. Kaushik ◽  
P. Maniar ◽  
J. Olowolafe ◽  
R. Jones ◽  
A. Campbell ◽  
...  
Keyword(s):  
Electric Fields ◽  
Sol Gel ◽  
Ferroelectric Material ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Lead Zirconium Titanate ◽  
Si Substrate ◽  
Film Capacitor ◽  
Pzt Films ◽  
High Dielectric

Lead zirconium titanate films (Pb (Zr,Ti) O3 or PZT) are being considered for potential application as dielectric films in memory technology due to their high dielectric constants. PZT is a ferroelectric material which shows spontaneous polarizability, reversible under applied electric fields. We report herein some results of TEM studies on thin film capacitor structures containing PZT films with platinum-titanium electrodes.The wafers had a stacked structure consisting of PZT/Pt/Ti/SiO2/Si substrate as shown in Figure 1. Platinum acts as electrode material and titanium is used to overcome the problem of platinum adhesion to the oxide layer. The PZT (0/20/80) films were deposited using a sol-gel method and the structure was annealed at 650°C and 800°C for 30 min in an oxygen ambient. XTEM imaging was done at 200KV with the electron beam parallel to <110> zone axis of silicon.Figure 2 shows the PZT and Pt layers only, since the structure had a tendency to peel off at the Ti-Pt interface during TEM sample preparation.

The need of electron microscopy in the study of domains and domain walls in ferroelectrics

1994 ◽  
Vol 52 ◽  
pp. 550-551
Author(s):  
Wenwu Cao
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
High Mobility ◽  
Continuum Theory ◽  
Polarization Vector ◽  
Ferroelectric Materials ◽  
Dielectric Constants ◽  
Nonlocal Coupling ◽  
Cubic Symmetry ◽  
Gradient Energy

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,

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