Dynamic pattern selection in polymorphic elastocapillarity

Soft Matter ◽  
2021 ◽  
Author(s):  
Jonghyun Ha ◽  
Yun Seong Kim ◽  
Ryan Siu ◽  
Sameh Tawfick
Keyword(s):  
Self Assembly ◽  
Industrial Processes ◽  
Pattern Selection ◽  
Natural Phenomena ◽  
Fine Hair ◽  
Dynamic Pattern ◽  
Hair Bundles

Drying of fine hair and fibers induces dramatic capillary-driven deformation, with important implications on natural phenomena and industrial processes. We recently observed peculiar self-assembly of hair bundles into various distinct...

Interactions and Dynamics in Charge-Stabilized Colloids

MRS Bulletin ◽  
1998 ◽  
Vol 23 (10) ◽  
pp. 24-31 ◽  
Author(s):  
John C. Crocker ◽  
David G. Grier
Keyword(s):  
Self Assembly ◽  
Colloidal Particles ◽  
Protein Crystallization ◽  
Colloidal Suspensions ◽  
Industrial Processes ◽  
Fluid Medium ◽  
Nano Structures ◽  
Naturally Occurring ◽  
Electrostatic Stabilization ◽  
Natural Tendency

Perhaps the most remarkable observation one can make about colloidal suspensions is that they exist at all. Particles dispersed in a fluid medium have a natural tendency to aggregate under the influence of van der Waals attraction. Yet the fortunes of a great many natural and industrial processes require colloidal particles to remain dispersed or at least to aggregate at a controlled rate. The existence of colloidal suspensions as varied as milk, inks, and metallic sols attests to the efficacy of a variety of stabilizing mechanisms. As early as 1809, Russel realized that many naturally occurring colloidal particles are charged. By the end of the century, Schultz and Hardy demonstrated that the resulting electro-static repulsions were strong enough to stabilize their suspensions against flocculating. This mechanism—arguably the best understood—continues to yield new surprises despite more than a century of analysis. The most recent burst of activity has been driven by the development of new and quite general techniques for measuring colloidal and macromolecular interactions. Its counterintuitive result—that like-charged particles some-times attract each other—may have ramifications in areas as diverse as protein crystallization, self-assembly of nano-structures, and the stabilization of industrial suspensions. This article touches briefly on the well-established theory of electrostatic stabilization in colloidal suspensions. The emphasis here is on the approximations that have provided the community with an analytical theory at the expense of overlooking recently discovered effects.

Numerical Investigation of Gas-Liquid Two-Phase Flows in a Cylindrical Channel

2021 ◽  
Vol 409 ◽  
pp. 39-48
Author(s):  
S. Gourari ◽  
Fateh Mebarek-Oudina ◽  
Oluwole Daniel Makinde ◽  
M. Rabhi
Keyword(s):  
Numerical Simulation ◽  
Cylindrical Channel ◽  
Three Dimensional ◽  
Industrial Processes ◽  
Natural Phenomena ◽  
Major Difficulty ◽  
Two Phase Flows ◽  
Two Phase ◽  
Hydrogen Water ◽  
Two Phases

Two-phase flows are widely encountered in many natural phenomena and industrial processes. The presence of one or more interfaces between the two phases presents a major difficulty which makes the modeling and the simulation of this type of flow complex. This work consists in performing a three-dimensional numerical simulation of a two-phase Hydrogen-Water flow inside a horizontal cylindrical channel. The results are obtained in the form of velocity contours, enthalpy and pressures.

scholarly journals Suspension dynamics: moving beyond steady

2014 ◽  
Vol 752 ◽  
pp. 1-4 ◽  
Author(s):  
Jason E. Butler
Keyword(s):  
Colloidal Particles ◽  
Sedimentation Velocity ◽  
Industrial Processes ◽  
Natural Phenomena ◽  
Concentrated Suspensions ◽  
Suspension Flows ◽  
Wide Range ◽  
Suspension Dynamics ◽  
Oscillatory Rheology ◽  
Neutrally Buoyant

AbstractThe dynamics of flowing, concentrated suspensions of non-colloidal particles continues to surprise, despite decades of work and the widespread importance of suspension transport properties to industrial processes and natural phenomena. Blanc, Lemaire & Peters (J. Fluid Mech., 2014, vol. 746, R4) report a striking example. They probed the time-dependent dynamics of concentrated suspensions of rigid and neutrally buoyant spheres by simultaneously measuring the oscillatory rheology and the sedimentation rate of a falling ball. The sedimentation velocity of the ball through the suspension depends strongly on the frequency of oscillation, though the rheology was found to be independent of frequency. The results demonstrate the complexities of suspension flows and highlight opportunities for improving models by exploring suspension dynamics and rheology over a wide range of conditions, beyond steady and unidirectional ones.

The Role and Implications of Bassanite as a Stable Precursor Phase to Gypsum Precipitation

Science ◽  
2012 ◽  
Vol 336 (6077) ◽  
pp. 69-72 ◽  
Author(s):  
A. E. S. Van Driessche ◽  
L. G. Benning ◽  
J. D. Rodriguez-Blanco ◽  
M. Ossorio ◽  
P. Bots ◽  
...  
Keyword(s):  
Self Assembly ◽  
Calcium Sulfate ◽  
Water Desalination ◽  
The Self ◽  
Industrial Processes ◽  
Time Resolved ◽  
Gypsum Precipitation ◽  
Precursor Phase ◽  
Stage Process ◽  
High Resolution Microscopy

Calcium sulfate minerals such as gypsum play important roles in natural and industrial processes, but their precipitation mechanisms remain largely unexplored. We used time-resolved sample quenching and high-resolution microscopy to demonstrate that gypsum forms via a three-stage process: (i) homogeneous precipitation of nanocrystalline hemihydrate bassanite below its predicted solubility, (ii) self-assembly of bassanite into elongated aggregates co-oriented along their c axis, and (iii) transformation into dihydrate gypsum. These findings indicate that a stable nanocrystalline precursor phase can form below its bulk solubility and that in the CaSO4 system, the self-assembly of nanoparticles plays a crucial role. Understanding why bassanite forms prior to gypsum can lead to more efficient anti-scaling strategies for water desalination and may help to explain the persistence of CaSO4 phases in regions of low water activity on Mars.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

The Nature of Rapidly Extracted Phycocyanin from the Blue-Green Alga Plectonema Boryanum

1971 ◽  
Vol 29 ◽  
pp. 366-367
Author(s):  
M. Kessel ◽  
R. MacColl
Keyword(s):  
Self Assembly ◽  
Analytical Ultracentrifugation ◽  
Uranyl Acetate ◽  
The Self ◽  
Major Protein ◽  
Subunit Structure ◽  
Blue Green Alga ◽  
Thin Sections ◽  
Blue Green Algae ◽  
Cacodylate Buffer

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.

Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 16-17
Author(s):  
Alan S. Rudolph ◽  
Ronald R. Price
Keyword(s):  
Real Time ◽  
Self Assembly ◽  
Freeze Drying ◽  
Video Capture ◽  
Drying Process ◽  
Artificial Membranes ◽  
The Past ◽  
Cryo Electron Microscopy ◽  
Spherical Structures ◽  
Capture Techniques

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

Biomimetic materials: An introduction

1992 ◽  
Vol 50 (2) ◽  
pp. 1020-1021 ◽  
Author(s):  
M. Sarikaya ◽  
J. T. Staley ◽  
I. A. Aksay
Keyword(s):  
Self Assembly ◽  
Structural Control ◽  
Hierarchical Structures ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Length Scale ◽  
Spider Webs ◽  
Biomimetic Materials ◽  
Synthetic Materials ◽  
All Ceramic

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).

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