Temporal Evolution of Superlattice Contraction and Defect-Induced Strain Anisotropy in Mesocrystals during Nanocube Self-Assembly

A laboratory in situ grazing-incidence small-angle X-ray scattering (GISAXS) tracking of the self-assembled growth of a regular 3D Ge quantum dot (QD) structure in an amorphous Al2O3 matrix during the ion beam sputter deposition of a periodic Ge/Al2O3 multilayer on silicon is reported. A 573 K substrate temperature proved to be necessary to achieve the self-assembly effect. Relying on a fast repeated acquisition of GISAXS patterns, the temporal evolution of the growing 3D Ge QD structure was analyzed bilayer by bilayer to determine its type, lateral and vertical correlation lengths, and inter-QD distance. The QD structure was found to have body-centered tetragonal lattice type with ABA stacking, with the lattice parameters refined by fitting the final GISAXS pattern relying on a paracrystal model. A single set of paracrystal parameters enables one to simulate the temporal evolution of the in situ GISAXS patterns throughout the deposition process, suggesting that the Ge QD self-assembly is driven from the very beginning solely by the growing surface morphology. Ex situ GISAXS and X-ray reflectivity measurements along with a cross-section high-resolution transmission electron microscopy analysis complete the study.

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Electrical Signature of Ultrasound-Induced Anisotropic Self-Assembly of Poly(3-Hexylthiophene) (P3HT) during Channel Formation

Applied Sciences ◽

10.3390/app10196886 ◽

2020 ◽

Vol 10 (19) ◽

pp. 6886

Author(s):

Youngjun Kim ◽

Byoung Nam Park

Keyword(s):

Self Assembly ◽

Temporal Evolution ◽

Drain Current ◽

Ultrasound Irradiation ◽

Channel Formation ◽

P3ht Film ◽

In Situ Raman Spectroscopy ◽

In Situ Raman ◽

Sheet Conductance

We probed ultrasound irradiation-induced structural ordering of poly(3-hexylthiophene) (P3HT) chains during solidification of a sonicated P3HT solution by monitoring the temporal evolution of the electrical and spectroscopic signals. We observed a peak source-drain current in the test devices during the electrical channel formation, followed by a significant decrease, which has not been observed in the pristine P3HT solution as the solvent evaporates. Through P3HT concentration-dependent gated-sheet conductance and in-situ Raman spectroscopy measurements during channel formation, we found that the competition between aggregation of the disentangled P3HT chains in solution by sonication and the concentration-dependent chain interactions with solvent evaporation led to a distinct electrical signature in the channel formation of the sonicated P3HT film compared to that of the pristine P3HT. The finding provides insights into new opportunities through optimization between the thermodynamic and kinetic considerations in designing pre-deposition treatments for enhanced charge transport.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083035 ◽

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.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065870 ◽

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.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010216x ◽

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.

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Biomimetic materials: An introduction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129735 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1020-1021 ◽

Cited By ~ 1

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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Interrelationship of the cellular distribution and secretion of regular structure (RS) protein in Bacillus licheniformis nm 105

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123969 ◽

1992 ◽

Vol 50 (1) ◽

pp. 712-713

Author(s):

Xiaorong Zhu ◽

Richard McVeigh ◽

Bijan K. Ghosh

Keyword(s):

Alkaline Phosphatase ◽

Bacillus Licheniformis ◽

Self Assembly ◽

Gel Electrophoresis ◽

Culture Supernatant ◽

Regular Structure ◽

The Self ◽

Cellular Distribution ◽

Structural Protein ◽

Laboratory Cultures

A mutant of Bacillus licheniformis 749/C, NM 105 exhibits some notable properties, e.g., arrest of alkaline phosphatase secretion and overexpression and hypersecretion of RS protein. Although RS is known to be widely distributed in many microbes, it is rarely found, with a few exceptions, in laboratory cultures of microorganisms. RS protein is a structural protein and has the unusual properties to form aggregate. This characteristic may have been responsible for the self assembly of RS into regular tetragonal structures. Another uncommon characteristic of RS is that enhanced synthesis and secretion which occurs when the cells cease to grow. Assembled RS protein with a tetragonal structure is not seen inside cells at any stage of cell growth including cells in the stationary phase of growth. Gel electrophoresis of the culture supernatant shows a very large amount of RS protein in the stationary culture of the B. licheniformis. It seems, Therefore, that the RS protein is cotranslationally secreted and self assembled on the envelope surface.

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Self Assembly in Supramolecular Systems

10.1039/9781847551863 ◽

2007 ◽

Keyword(s):

Self Assembly ◽

Supramolecular Systems

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Porphyrin-functionalized coordination star polymers and their potential applications in photodynamic therapy

Polymer Chemistry ◽

10.1039/c9py01391a ◽

2019 ◽

Vol 10 (45) ◽

pp. 6116-6121 ◽

Cited By ~ 3

Author(s):

Tan Ji ◽

Lei Xia ◽

Wei Zheng ◽

Guang-Qiang Yin ◽

Tao Yue ◽

...

Keyword(s):

Photodynamic Therapy ◽

Self Assembly ◽

Star Polymers ◽

New Family ◽

Potential Applications

We present a new family of porphyrin-functionalized coordination star polymers prepared through combination of coordination-driven self-assembly and post-assembly polymerization. Their self-assembly behaviour in water and potential for photodynamic therapy were demonstrated.

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Molecular Forces and Self Assembly

10.1017/cbo9780511811531 ◽

2009 ◽

Cited By ~ 135

Author(s):

Barry W. Ninham ◽

Pierandrea Lo Nostro

Keyword(s):

Self Assembly ◽

Molecular Forces

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