scholarly journals Segmentation in cohesive systems constrained by elastic environments

2017 ◽  
Vol 375 (2093) ◽  
pp. 20160160 ◽  
Author(s):  
I. Novak ◽  
L. Truskinovsky
Keyword(s):  
Self Assembly ◽  
Lattice Structure ◽  
Media Theory ◽  
Biological Applications ◽  
Competing Interactions ◽  
Complete Set ◽  
Mass Spring ◽  
Peculiar Nature ◽  
The Continuum

The complexity of fracture-induced segmentation in elastically constrained cohesive (fragile) systems originates from the presence of competing interactions. The role of discreteness in such phenomena is of interest in a variety of fields, from hierarchical self-assembly to developmental morphogenesis. In this paper, we study the analytically solvable example of segmentation in a breakable mass–spring chain elastically linked to a deformable lattice structure. We explicitly construct the complete set of local minima of the energy in this prototypical problem and identify among them the states corresponding to the global energy minima. We show that, even in the continuum limit, the dependence of the segmentation topology on the stretching/pre-stress parameter in this problem takes the form of a devil's type staircase. The peculiar nature of this staircase, characterized by locking in rational microstructures, is of particular importance for biological applications, where its structure may serve as an explanation of the robustness of stress-driven segmentation. This article is part of the themed issue ‘Patterning through instabilities in complex media: theory and applications.’

A flux-based stoichiometric model of enhanced biological phosphorus removal metabolism

1998 ◽  
Vol 37 (4-5) ◽  
pp. 609-613
Author(s):  
J. Pramanik ◽  
P. L. Trelstad ◽  
J. D. Keasling
Keyword(s):  
Phosphorus Removal ◽  
Reaction Network ◽  
Bacterial Biomass ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Stoichiometric Model ◽  
Aerobic Reactor ◽  
Complete Set ◽  
Biological Phosphorus

Enhanced biological phosphorus removal (EBPR) in wastewater treatment involves metabolic cycling through the biopolymers polyphosphate (polyP), polyhydroxybutyrate (PHB), and glycogen. This cycling is induced through treatment systems that alternate between carbon-rich anaerobic and carbon-poor aerobic reactor basins. While the appearance and disappearance of these biopolymers has been documented, the intracellular pressures that regulate their synthesis and degradation are not well understood. Current models of the EBPR process have examined a limited number of metabolic pathways that are frequently lumped into an even smaller number of “reactions.” This work, on the other hand, uses a stoichiometric model that contains a complete set of the pathways involved in bacterial biomass synthesis and energy production to examine EBPR metabolism. Using the stoichiometric model we were able to analyze the role of EBPR metabolism within the larger context of total cellular metabolism, as well as predict the flux distribution of carbon and energy fluxes throughout the total reaction network. The model was able to predict the consumption of PHB, the degradation of polyP, the uptake of acetate and the release of Pi. It demonstrated the relationship between acetate uptake and Pi release, and the effect of pH on this relationship. The model also allowed analysis of growth metabolism with respect to EBPR.

Directive Effect of Chain Length in Modulating Peptide Nano-assemblies

2020 ◽  
Vol 27 (9) ◽  
pp. 923-929
Author(s):  
Gaurav Pandey ◽  
Prem Prakash Das ◽  
Vibin Ramakrishnan
Keyword(s):  
Electron Microscopy ◽  
Amino Acids ◽  
Light Scattering ◽  
Chain Length ◽  
Self Assembly ◽  
The Self ◽  
Ionic Charge ◽  
Self Assembling ◽  
Biophysical Techniques

Background: RADA-4 (Ac-RADARADARADARADA-NH2) is the most extensively studied and marketed self-assembling peptide, forming hydrogel, used to create defined threedimensional microenvironments for cell culture applications. Objectives: In this work, we use various biophysical techniques to investigate the length dependency of RADA aggregation and assembly. Methods: We synthesized a series of RADA-N peptides, N ranging from 1 to 4, resulting in four peptides having 4, 8, 12, and 16 amino acids in their sequence. Through a combination of various biophysical methods including thioflavin T fluorescence assay, static right angle light scattering assay, Dynamic Light Scattering (DLS), electron microscopy, CD, and IR spectroscopy, we have examined the role of chain-length on the self-assembly of RADA peptide. Results: Our observations show that the aggregation of ionic, charge-complementary RADA motifcontaining peptides is length-dependent, with N less than 3 are not forming spontaneous selfassemblies. Conclusion: The six biophysical experiments discussed in this paper validate the significance of chain-length on the epitaxial growth of RADA peptide self-assembly.

Sticky ends in a self-assembling ABA triblock copolymer: the role of ureas in stimuli-responsive hydrogels

2019 ◽  
Vol 4 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Ryan T. Shafranek ◽  
Joel D. Leger ◽  
Song Zhang ◽  
Munira Khalil ◽  
Xiaodan Gu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Viscoelastic Properties ◽  
Triblock Copolymer ◽  
Thermal Response ◽  
Stimuli Responsive ◽  
Self Assembling ◽  
Polymeric Hydrogels ◽  
Aba Triblock Copolymer ◽  
Responsive Hydrogels

Directed self-assembly in polymeric hydrogels allows tunability of thermal response and viscoelastic properties.

scholarly journals Understanding the role of conjugation length on the self-assembly behaviour of oligophenyleneethynylenes

2021 ◽  
Author(s):  
Beatriz Matarranz ◽  
Goutam Ghosh ◽  
Ramesh Kandanelli ◽  
Angel Sampedro ◽  
Kalathil K. Kartha ◽  
...  
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Conjugation Length ◽  
The Relationship

We unravel the relationship between conjugation length and self-assembly behaviour of oligophenyleneethynylenes (OPEs).

scholarly journals On the Role of Peripheral H‐bonding Directors in the Tubular Self‐assembly of Dinucleobase Monomers

ChemPlusChem ◽  
2021 ◽  
Author(s):  
Violeta Vázquez-González ◽  
María J. Mayoral ◽  
Fatima Aparicio ◽  
Paula Martínez-Arjona ◽  
David Gonzalez Rodriguez
Keyword(s):  
Self Assembly

Role of integrative medicine in the continuum of care of breast cancer patients in the Indian context

2021 ◽  
Author(s):  
Partha Basu ◽  
Richa Tripathi ◽  
Ravi Mehrotra ◽  
Koninika Ray ◽  
Anurag Srivastava ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Patients ◽  
Integrative Medicine ◽  
Continuum Of Care ◽  
Breast Cancer Patients ◽  
Indian Context ◽  
The Continuum

scholarly journals Interactions between an Associative Amphiphilic Block Polyelectrolyte and Surfactants in Water: Effect of Charge Type on Solution Properties and Aggregation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1729
Author(s):  
Patrizio Raffa
Keyword(s):  
Surface Tension ◽  
Self Assembly ◽  
Interaction Model ◽  
Industrial Applications ◽  
Molecular Organization ◽  
Different Types ◽  
Solution Rheology ◽  
Interesting Class ◽  
First Time

The study of interactions between polyelectrolytes (PE) and surfactants is of great interest for both fundamental and applied research. These mixtures can represent, for example, models of self-assembly and molecular organization in biological systems, but they are also relevant in industrial applications. Amphiphilic block polyelectrolytes represent an interesting class of PE, but their interactions with surfactants have not been extensively explored so far, most studies being restricted to non-associating PE. In this work, interactions between an anionic amphiphilic triblock polyelectrolyte and different types of surfactants bearing respectively negative, positive and no charge, are investigated via surface tension and solution rheology measurements for the first time. It is evidenced that the surfactants have different effects on viscosity and surface tension, depending on their charge type. Micellization of the surfactant is affected by the presence of the polymer in all cases; shear viscosity of polymer solutions decreases in presence of the same charge or nonionic surfactants, while the opposite charge surfactant causes precipitation. This study highlights the importance of the charge type, and the role of the associating hydrophobic block in the PE structure, on the solution behavior of the mixtures. Moreover, a possible interaction model is proposed, based on the obtained data.

scholarly journals Substrate wettability guided oriented self assembly of Janus particles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Meneka Banik ◽  
Shaili Sett ◽  
Chirodeep Bakli ◽  
Arup Kumar Raychaudhuri ◽  
Suman Chakraborty ◽  
...  
Keyword(s):  
Self Assembly ◽  
Janus Particles ◽  
Water Molecules ◽  
Functional Coatings ◽  
Hexagonal Close Packed ◽  
Local Densities ◽  
Inhomogeneous Properties ◽  
Metal Polymer ◽  
Specific Orientation

AbstractSelf-assembly of Janus particles with spatial inhomogeneous properties is of fundamental importance in diverse areas of sciences and has been extensively observed as a favorably functionalized fluidic interface or in a dilute solution. Interestingly, the unique and non-trivial role of surface wettability on oriented self-assembly of Janus particles has remained largely unexplored. Here, the exclusive role of substrate wettability in directing the orientation of amphiphilic metal-polymer Bifacial spherical Janus particles, obtained by topo-selective metal deposition on colloidal Polymestyere (PS) particles, is explored by drop casting a dilute dispersion of the Janus colloids. While all particles orient with their polymeric (hydrophobic) and metallic (hydrophilic) sides facing upwards on hydrophilic and hydrophobic substrates respectively, they exhibit random orientation on a neutral substrate. The substrate wettability guided orientation of the Janus particles is captured using molecular dynamic simulation, which highlights that the arrangement of water molecules and their local densities near the substrate guide the specific orientation. Finally, it is shown that by spin coating it becomes possible to create a hexagonal close-packed array of the Janus colloids with specific orientation on differential wettability substrates. The results reported here open up new possibilities of substrate-wettability driven functional coatings of Janus particles, which has hitherto remained unexplored.

scholarly journals Few Body Effects in the Electron and Positron Impact Ionization of Atoms

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 33
Author(s):  
R.I. Campeanu ◽  
Colm T. Whelan
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Differential Cross ◽  
Impact Ionization ◽  
Inert Gas ◽  
Interference Effects ◽  
Positron Impact ◽  
Competing Interactions ◽  
Energy Sharing

Triple differential cross sections (TDCS) are presented for the electron and positron impact ionization of inert gas atoms in a range of energy sharing geometries where a number of significant few body effects compete to define the shape of the TDCS. Using both positrons and electrons as projectiles has opened up the possibility of performing complementary studies which could effectively isolate competing interactions that cannot be separately detected in an experiment with a single projectile. Results will be presented in kinematics where the electron impact ionization appears to be well understood and using the same kinematics positron cross sections will be presented. The kinematics are then varied in order to focus on the role of distortion, post collision interaction (pci), and interference effects.

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