Thermal convection and related instabilities in models of crystal growth from the melt on earth and in microgravity: Past history and current status

2005 ◽  
Vol 40 (6) ◽  
pp. 531-549 ◽  
Author(s):  
Marcello Lappa
Keyword(s):  
Crystal Growth ◽  
Thermal Convection ◽  
Past History ◽  
Current Status ◽  
Models Of Crystal Growth

Computer Models of Crystal Growth

Science ◽  
1980 ◽  
Vol 208 (4442) ◽  
pp. 355-363 ◽  
Author(s):  
G. H. Gilmer
Keyword(s):  
Crystal Growth ◽  
Computer Models ◽  
Models Of Crystal Growth

scholarly journals Current status of GaN crystal growth by sublimation sandwich technique

1998 ◽  
Vol 3 ◽  
Author(s):  
P. G. Baranov ◽  
E. N. Mokhov ◽  
A. O. Ostroumov ◽  
M. G. Ramm ◽  
M. S. Ramm ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Growth Process ◽  
Growth Conditions ◽  
Current Status ◽  
Gaseous Species ◽  
Double Crystal ◽  
Paramagnetic Resonance ◽  
Sandwich Technique ◽  
Microscopy Technique ◽  
Gan Crystal

The current status of GaN crystal growth using the Sublimation Sandwich Technique is discussed in the paper. We use modeling to analyze gas dynamics in the reactor and the supply of the main gaseous species into the growth cell under growth conditions used in experiments. Important features of growth process — non-equilibrium cracking of ammonia, partial sticking of ammonia at the growing surface and kinetic limitation of GaN thermal decomposition — are taken into account in the model. Growth is carried out on sapphire and 6H-SiC substrates in ammonia atmosphere using a Ga/GaN mixture as the group-III element source. Single crystals of GaN of size 15×15 mm and up to 0.5 mm thick are normally grown with the optimized growth rates of 0.25-0.35 mm/h. The GaN crystals are characterized by photoluminescence, by the Color Cathodoluminescence Scanning Electron Microscopy technique, by differential double-crystal and triple-crystal X-ray diffractometry, and by electron paramagnetic resonance. Mechanisms of sublimation growth of GaN and physical limitations of the growth process are discussed.

Analytic treatment of stochastic models of crystal growth

1977 ◽  
Vol 83 (1) ◽  
pp. 129-138 ◽  
Author(s):  
H. Pfeiffer ◽  
W. Haubenreisser ◽  
Th. Klupsch
Keyword(s):  
Crystal Growth ◽  
Stochastic Models ◽  
Analytic Treatment ◽  
Models Of Crystal Growth

COMPUTER MODEL OF BIOPOLYMER CRYSTAL GROWTH AND AGGREGATION BY ADDITION OF MACROMOLECULAR UNITS — A COMPARATIVE STUDY

2006 ◽  
Vol 17 (07) ◽  
pp. 1037-1053 ◽  
Author(s):  
J. SIÓDMIAK ◽  
A. GADOMSKI
Keyword(s):  
Crystal Growth ◽  
Crystal Surface ◽  
Three Dimensional ◽  
Protein Molecule ◽  
Data Bank ◽  
Growth Unit ◽  
Lattice Monte Carlo ◽  
Tetragonal Crystals ◽  
And Migration ◽  
Models Of Crystal Growth

We discuss the results of a computer simulation of the biopolymer crystal growth and aggregation based on the 2D lattice Monte Carlo technique and the HP approximation of the biopolymers. As a modeled molecule (growth unit) we comparatively consider the previously studied non-mutant lysozyme protein, Protein Data Bank (PDB) ID: 193L, which forms, under a certain set of thermodynamic-kinetic conditions, the tetragonal crystals, and an amyloidogenic variant of the lysozyme, PDB ID: 1LYY, which is known as fibril-yielding and prone-to-aggregation agent. In our model, the site-dependent attachment, detachment and migration processes are involved. The probability of growth unit motion, attachment and detachment to/from the crystal surface are assumed to be proportional to the orientational factor representing the anisotropy of the molecule. Working within a two-dimensional representation of the truly three-dimensional process, we also argue that the crystal grows in a spiral way, whereby one or more screw dislocations on the crystal surface give rise to a terrace. We interpret the obtained results in terms of known models of crystal growth and aggregation such as B-C-F (Burton-Cabrera-Frank) dislocation driven growth and M-S (Mullins-Sekerka) instability concept, with stochastic aspects supplementing the latter. We discuss the conditions under which crystals vs non-crystalline protein aggregates appear, and how the process depends upon difference in chemical structure of the protein molecule seen as the main building block of the elementary crystal cell.

OIL SPILL DISPERSANTS – CURRENT STATUS AND FUTURE OUTLOOK

1971 ◽  
Vol 1971 (1) ◽  
pp. 263-270 ◽  
Author(s):  
Gerard P. Canevari
Keyword(s):  
Oil Spill ◽  
Oil Spills ◽  
Past History ◽  
Laboratory Data ◽  
Field Application ◽  
Current Status ◽  
Future Outlook ◽  
Application Techniques ◽  
Pros And Cons ◽  
Oil Spill Cleanup

ABSTRACT The use of chemical dispersants for the handling of oil spills has had a brief but highly turbulent history. Despite extensive laboratory data and field application experience, their role in oil spill cleanup is still controversial. This paper reviews some of this past history as background in order to derive the pros and cons regarding their use. Opinions vary from an extreme of no use whatsoever to an acceptance of this as the only practical technique to combat an oil spill under rough sea conditions. Improvements in the formulation of dispersants during the past several years are reviewed. These innovations involve modifications to improve effectiveness, application techniques and toxicological properties. A brief outline of the mechanism of dispersing is presented to permit a better understanding of these formulation modifications and the manner in which said changes influence dispersant properties. The future outlook for dispersants, based on current and anticipated research in this field, is also discussed. This research involves biological as well as operational aspects of dispersants.

Sign in / Sign up

Export Citation Format

Share Document