Stability of symmetric inclined flow of a liquid film in the presence of phase transition

1993 ◽  
Vol 63 (4) ◽  
pp. 446-448
Author(s):  
V. I. Panchuk ◽  
G. A. Chechko
Keyword(s):  
Phase Transition ◽  
Liquid Film ◽  
Inclined Flow

Effect of heat source temperature, nanostructure, and wettability on explosive boiling of ultra-thin liquid argon film over graphene substrate: a molecular dynamics study

2020 ◽  
Vol 16 ◽  
Author(s):  
Haiyan Zhang ◽  
Cunhui Li ◽  
Yi Wang ◽  
Yingmin Zhu ◽  
Weidong Wang
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Heat Source ◽  
Liquid Film ◽  
Substrate Surface ◽  
Thin Liquid Film ◽  
Liquid Argon ◽  
Explosive Boiling ◽  
Source Temperature ◽  
Heat Source Temperature

Background: The study on explosive boiling phenomenon has received increasing attention because it involves many industries, such as advanced micro-, nano-electromechanical and nano-electronic cooling systems, laser steam cleaning and so on. Objective: In present work, the explosive boiling of ultra-thin liquid film over two-dimensional nanomaterial surface in confined space with particular emphasis under the three different influencing factors: various heights of nanostructures, various wetting conditions of solid-liquid interface as well as various heat source temperatures. Methods: Molecular Dynamics simulations (MDs) in present work have been adopted to simulate the whole explosive boiling process. Results: For different heat source temperature case, the higher the heat temperature is, the less time the explosive boiling spends after relaxation. For nanostructure case, nanostructure surface significantly increases heat transfer rate and then leads to the increase of phase transition rate of explosive boiling. For different wetting property case, the increase of surface wettability results in increase of phase transition to some degree. Conclusion: The addition of nanostructures, the higher heat source temperature and good wettability between thin liquid film and substrate surface dramatically improve thermal heat transfer from solid surface to liquid film, which will obviously give rise to explosive boiling occur. in addition, the non-vaporized argon layer still exists in these three factors in spite of continuous thermal transmission from substrate surface to liquid argon film adjacent to solid surface even other vaporized argon atoms.

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.

Dynamic low-dose electron diffraction and imaging of phase transitions in polymers

1993 ◽  
Vol 51 ◽  
pp. 890-891
Author(s):  
David C. Martin ◽  
Jun Liao
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Electron Diffraction ◽  
Low Dose ◽  
Dark Field ◽  
Continuous Change ◽  
Selected Area Electron Diffraction ◽  
Resolution Electron ◽  
Chain Axis ◽  
High Resolution Electron Micrographs

By careful control of the electron beam it is possible to simultaneously induce and observe the phase transformation from monomer to polymer in certain solid-state polymcrizable diacetylenes. The continuous change in the crystal structure from DCHD diacetylene monomer (a=1.76 nm, b=1.36 nm, c=0.455 nm, γ=94 degrees, P2l/c) to polymer (a=1.74 nm, b=1.29 nm, c=0.49 nm, γ=108 degrees, P2l/c) occurs at a characteristic dose (10−4C/cm2) which is five orders of magnitude smaller than the critical end point dose (20 C/cm2). Previously we discussed the progress of this phase transition primarily as observed down the [001] zone (the chain axis direction). Here we report on the associated changes of the dark field (DF) images and selected area electron diffraction (SAED) patterns of the crystals as observed from the side (i.e., in the [hk0] zones).High resolution electron micrographs (HREM), DF images, and SAED patterns were obtained on a JEOL 4000 EX HREM operating at 400 kV.

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