Change in Viscoelastic Behaviors Due to Phase Transition of the Assembly Comprising Cetyltrimethylammonium Chloride/Cetyl Alcohol/Water

Langmuir ◽  
1999 ◽  
Vol 15 (13) ◽  
pp. 4388-4391 ◽  
Author(s):  
Yoshifumi Yamagata ◽  
Mamoru Senna
Keyword(s):  
Phase Transition ◽  
Cetyl Alcohol ◽  
Cetyltrimethylammonium Chloride ◽  
Alcohol Water ◽  
Viscoelastic Behaviors

Cholesteryl Cetyl Carbonate as a Smart Material for Drug Delivery Application

2008 ◽  
Vol 55-57 ◽  
pp. 713-716
Author(s):  
N. Aeinlang ◽  
T. Srichana ◽  
S. Songkro
Keyword(s):  
Phase Transition ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Weight Ratio ◽  
Liquid Extraction ◽  
Cetyl Alcohol ◽  
Isotropic Liquid ◽  
Liquid Liquid Extraction ◽  
Solid Crystal ◽  
Flash Column Chromatography

Cholesteryl cetyl carbonate (CCC) was synthesized from cetyl alcohol and cholesteryl chloroformate. Cholesteryl cetyl carbonate mixture (CCCM) was obtained from the reaction. CCCM was purified by liquid-liquid extraction and flash column chromatography. Thermotropic liquid crystal was formed in both pure CCC and CCCM. CCCM is composed of cholesterol, cetyl alcohol and CCC (30:20:50, weight ratio). FTIR and NMR were employed to confirm the functional groups of CCC. Thermal properties of CCC were determined by DSC and polarized light microscope. The phase transition from solid crystal to smectic appears at 42 °C, smectic to nematic appears at 54 °C and nematic to isotropic liquid appears at 73 °C. Indomethacin (IDM) could be incorporated into CCC and properties of CCC-IDM mixture stayed as liquid crystalline phase.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

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