Orthogonal smectic and nematic ordering in three-ring polar bent-core molecules with anti-parallel arrangement

2017 ◽  
Vol 41 (13) ◽  
pp. 5403-5411 ◽  
Author(s):  
Supreet Kaur ◽  
Vidhika Punjani ◽  
Golam Mohiuddin ◽  
Santanu Kumar Pal
Keyword(s):  
X Ray ◽  
Nematic Ordering ◽  
X Ray Scattering ◽  
Parallel Arrangement ◽  
Nematic Phases ◽  
Ray Scattering

Three-ring based BLCs exhibiting orthogonal smectic and nematic phases with antiparallel arrangement as derived from SCXRD and X-ray scattering results.

scholarly journals Electro-induced orientational ordering of anisotropic pigment nanoparticles

2013 ◽  
Vol 371 (1988) ◽  
pp. 20120257 ◽  
Author(s):  
Robert J. Greasty ◽  
Robert M. Richardson ◽  
Susanne Klein ◽  
David Cherns ◽  
Michael R. Thomas ◽  
...  
Keyword(s):  
Electric Fields ◽  
Orientational Order ◽  
Optical Response ◽  
Pigment Particle ◽  
X Ray ◽  
X Ray Scattering ◽  
Orientational Ordering ◽  
Nematic Phases ◽  
High Concentrations ◽  
Ray Scattering

The response of anisotropic pigment particle suspensions to externally applied electric fields has been explored for possible application in reflective display technologies. Three different types of pigment particle were suspended in dodecane, using a polymeric stabilizer, and showed Schlieren textures between crossed polarizers at high concentrations (greater than 25–30 wt%), indicating the formation of colloidal nematic phases. Orientational order parameters were determined by X-ray scattering, and the influence of polydispersity on the values is discussed. X-ray scattering measurements also demonstrated a change in the structure factor consistent with the onset of a colloidal nematic phase. In addition, the pigment particles were dispersed into various liquid crystal hosts at low concentrations (less than 5 wt%) with and without the presence of mesogenic mimic stabilizers. However, the influence of these stabilizers on orientational ordering could not be confirmed. The electro-induced ordering determined via scattering was related to the electro-optical response of each suspension using a simple model. The particles in nematic hosts not only showed a high degree of orientational ordering at lower electric field strengths, but also showed a reduction in stability. Although these systems have shown strong orientational ordering, the optical response has been limited by the intrinsic shape of the pigment particles and the distribution of the transition dipoles moments within them. Nevertheless, the feasibility of developing materials for display applications has been demonstrated.

A Small-Angle X-ray Scattering Study of the Lyotropic Nematic Phase of Vanadium Pentoxide Gels

1997 ◽  
Vol 30 (5) ◽  
pp. 727-732 ◽  
Author(s):  
P. Davidson ◽  
C. Bourgaux ◽  
P. Sergot ◽  
J. Livage
Keyword(s):  
Vanadium Pentoxide ◽  
Small Angle ◽  
Nematic Phase ◽  
Average Distance ◽  
Building Blocks ◽  
X Ray ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Nematic Phases ◽  
Ray Scattering

Aqueous suspensions of vanadium pentoxide (V2O5) ribbons, also called Zocher phases, are known to display a lyotropic nematic phase. In this paper, it is shown how the small-angle X-ray scattering (SAXS) technique can provide useful information on the building blocks and their organization in this phase. SAXS experiments were performed either on unoriented samples or on samples aligned by a magnetic field or by shear flow. The scattering is comparable to that of the other classic lyotropic nematic phases displayed by stiff organic rod-like particles such as the tobacco mosaic virus. Scattering studies show that the building blocks have a ribbon shape, that their thickness is 9 (1) Å and indirectly that their width is several 100 Å. Their length is known to be around a few thousand Å and therefore could not be measured by SAXS. By following the average distance between the ribbons as a function of concentration, it is shown that the swelling of the phase is one-dimensional at large concentrations and two-dimensional at low concentrations. Finally, estimates of the nematic order parameter of a single domain sample and of samples sheared in a Couette cell have been obtained.

A small-angle X-ray scattering study of the isotropic and nematic phases of V

2000 ◽  
Vol 2 (2) ◽  
pp. 191 ◽  
Author(s):  
O. Pelletier ◽  
C. Bourgaux ◽  
O. Diat ◽  
P. Davidson ◽  
J. Livage
Keyword(s):  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Nematic Phases ◽  
Ray Scattering

A small-angle X-ray scattering study of the isotropic and nematic phases of V2O5 suspensions

2000 ◽  
Vol 2 (2) ◽  
pp. 191-198 ◽  
Author(s):  
O. Pelletier ◽  
C. Bourgaux ◽  
O. Diat ◽  
P. Davidson ◽  
J. Livage
Keyword(s):  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Nematic Phases ◽  
Ray Scattering

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 502-503
Author(s):  
Eva-Maria Mandelkow ◽  
Ron Milligan
Keyword(s):  
Electron Microscopy ◽  
Dynamic Instability ◽  
Entire Solution ◽  
Reaction Scheme ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
A Chain ◽  
Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

X-ray scattering by 1D molecular Guinier-Preston zones in ordered smectic phases

1992 ◽  
Vol 2 (6) ◽  
pp. 899-913 ◽  
Author(s):  
Patrick Davidson ◽  
Elisabeth Dubois-Violette ◽  
Anne-Marie Levelut ◽  
Brigitte Pansu
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Smectic Phases ◽  
Ray Scattering

An X-ray Scattering Study of Laterally Modulated Structures: Investigation of Coherence and Resolution Effects with a Grating

1996 ◽  
Vol 6 (8) ◽  
pp. 1085-1094 ◽  
Author(s):  
A. Gibaud ◽  
J. Wang ◽  
M. Tolan ◽  
G. Vignaud ◽  
S. K. Sinha
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Modulated Structures ◽  
Scattering Study ◽  
Ray Scattering

Pixel detectors: New detectors for X-ray scattering

2002 ◽  
Vol 12 (6) ◽  
pp. 385-390 ◽  
Author(s):  
J.-F. Bérar ◽  
L. Blanquart ◽  
N. Boudet ◽  
P. Breugnon ◽  
B. Caillot ◽  
...  
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Pixel Detectors ◽  
Ray Scattering
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