scholarly journals Geological pattern formation by growth and dissolution in aqueous systems

2009 ◽  
Vol 466 (2115) ◽  
pp. 659-694 ◽  
Author(s):  
Paul Meakin ◽  
Bjørn Jamtveit
Keyword(s):  
Pattern Formation ◽  
Secondary Effect ◽  
Biological Processes ◽  
Formation Processes ◽  
Aqueous Systems ◽  
Interfacial Chemistry ◽  
Aqueous Chemistry ◽  
Turbulent Fluids ◽  
Supersaturated Solutions ◽  
Dissolution Of Minerals

Progress towards the development of a better understanding of the formation of geological patterns in wet systems due to precipitation and dissolution is reviewed. Emphasis is placed on the formation of terraces, stalactites, stalagmites and other carbonate patterns due to precipitation from flowing supersaturated solutions and the formation of scallops by dissolution in undersaturated turbulent fluids. In addition, the formation of spherulites, dendrites and very large, essentially euhedral, crystals is discussed. In most cases, the formation of very similar patterns as a result of the freezing/melting of ice and the precipitation/dissolution of minerals strongly suggests that complexity associated with aqueous chemistry, interfacial chemistry and biological processes has only a secondary effect on these pattern formation processes.

scholarly journals Towards an integrated experimental–theoretical approach for assessing the mechanistic basis of hair and feather morphogenesis

2012 ◽  
Vol 2 (4) ◽  
pp. 433-450 ◽  
Author(s):  
K. J. Painter ◽  
G. S. Hunt ◽  
K. L. Wells ◽  
J. A. Johansson ◽  
D. J. Headon
Keyword(s):  
Pattern Formation ◽  
Theoretical Approach ◽  
Spatial Patterning ◽  
Biological Processes ◽  
Chemical Basis ◽  
Alan Turing ◽  
Theoretical Approaches ◽  
Simple Demonstration ◽  
Mechanistic Basis ◽  
Elegant Solution

In his seminal 1952 paper, ‘The Chemical Basis of Morphogenesis’, Alan Turing lays down a milestone in the application of theoretical approaches to understand complex biological processes. His deceptively simple demonstration that a system of reacting and diffusing chemicals could, under certain conditions, generate spatial patterning out of homogeneity provided an elegant solution to the problem of how one of nature's most intricate events occurs: the emergence of structure and form in the developing embryo. The molecular revolution that has taken place during the six decades following this landmark publication has now placed this generation of theoreticians and biologists in an excellent position to rigorously test the theory and, encouragingly, a number of systems have emerged that appear to conform to some of Turing's fundamental ideas. In this paper, we describe the history and more recent integration between experiment and theory in one of the key models for understanding pattern formation: the emergence of feathers and hair in the skins of birds and mammals.

The Water-activity of Supersaturated Aqueous Solutions of NaCl, KCl, and K2SO4 at 25°C

1975 ◽  
Vol 53 (20) ◽  
pp. 3133-3140 ◽  
Author(s):  
Fabio Lenzi ◽  
Tuong-Tu Tran ◽  
Tjoon-Tow Teng
Keyword(s):  
Aqueous Solutions ◽  
Water Activity ◽  
Aqueous Systems ◽  
Activity Data ◽  
Self Consistent ◽  
The Individual ◽  
Supersaturated Solutions

Reverse application of the Reilly–Wood-Robinson and Zdanovskii–Stokes–Robinson equations to the water-activity data of various ternary aqueous systems containing NaCl, KCl, K2SO4 as one of the components yields self-consistent estimates of the water-activity of binary aqueous supersaturated solutions of the individual salts; these can be further extended by curvilinear extrapolation to give: [Formula: see text] with A1 = −3.28806 × 10−2, A2 = 1.12512 × 10−4, A3 = −4.30034 × 10−4, A4 = 2.70506 × 10−5, A5 = 1.43435 × 10−6, A6 = 1.30209 ×10−7, A7 = −1.51941 × 10−8, A8 = 1.00520 × 10−9, A9 = −4.21593 × 10−10, A10 = 2.62532 × 10−11, valid to aw(NaCl) = 0.5422, [Formula: see text][Formula: see text]with B1 = −3.21884 × 10−2, B2 = 9.77773 × 10−4, B3 = −6.05349 × 10−4, B4 = 1.18422 × 10−4, B5 = −7.91572 × 10−6, B6 = −3.88125 × 10−8, B7 = 1.55125 × 10−8, valid to aw(KCl) = 0.7115, [Formula: see text][Formula: see text] with C1 = −4.16810 × 10−2, C2 = 1.16033 × 10−2, C3 = −4.80543 × 10−3, C4 = 7.15536 x 10−4, valid to [Formula: see text][Formula: see text]

scholarly journals Identification of an Akinete Marker Gene in Anabaena variabilis

2002 ◽  
Vol 184 (9) ◽  
pp. 2529-2532 ◽  
Author(s):  
Ruanbao Zhou ◽  
C. Peter Wolk
Keyword(s):  
Pattern Formation ◽  
Marker Gene ◽  
Anabaena Variabilis ◽  
Formation Processes ◽  
Akinete Formation ◽  
Rare Opportunity

ABSTRACT Cyanobacteria that form akinetes as well as heterocysts present a rare opportunity to investigate the relationships between alternative differentiation processes and pattern formation processes in a single bacterium. Because no akinete marker gene has been identified, akinete formation has been little studied genetically. We report the first identification of an akinete marker gene.

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