Biomimetic materials

2018 ◽  
Author(s):  
Julian Vincent
Keyword(s):  
Hydrogen Bonds ◽  
Driving Force ◽  
Strain Energy ◽  
Molecular Level ◽  
Biological Materials ◽  
Low Energy ◽  
Stress Concentrations ◽  
Liquid Crystallinity ◽  
Biomimetic Materials

Biological materials present the conventional materials scientist with alternative ways of achieving durability, recyclability, and adaptability. Technical materials are commonly designed to resist the initiation of cracks; biological materials control disaster by initiating failure where it can be more closely controlled and the strain energy can be more easily absorbed, at the same time controlling shape so that stress concentrations are avoided in sensitive areas. Most materials are hydrated and soft, achieving stiffness by dehydration and mineralization. The low energy of the predominant hydrogen bonds allows relatively easy breakdown and recycling of the units of biological materials. Since most biological materials are metabolically accessible (obvious exceptions are keratins and wood) they can be recycled and repaired in situ, adapting the organism to changing circumstances internally and externally. At the molecular level, liquid crystallinity is a driving force.

Coherency Strain Energy in any Crystal System: Applications to in Situ Observations of Cigm in Calcite

1990 ◽  
Vol 205 ◽  
Author(s):  
R.S. May ◽  
B. Evans
Keyword(s):  
Driving Force ◽  
Migration Rate ◽  
Strain Energy ◽  
Solute Concentration ◽  
Coherency Strain ◽  
Solute Diffusion ◽  
Boundary Orientation ◽  
In Situ Observations ◽  
And Migration

AbstractIn situ observations of CIGM in CaCO3 bicrystals with a SrCO3 solute source were made. The change in boundary orientation and migration rate were compared with solute concentration. The liquid film model for coherency strain Induced migration was generalized to any non-cubic system and applied to CaCO3-SrCO3. The coherent layer was modeled as a thin film on an infinite half-space. The strain energy was found from solution of the Hooke's law expressions transformed to the appropriate coordinate system. For triclinic or monoclinic films the strain tensor was found by an eigenvector decomposition of the transformation matrix that defined the lattice parameter change with composition. High anisotropy of Vegard's law constants for CaCO3-SrCO3 caused (111) to have the lowest coherency strain per unit solute. Surfaces perpendicular to (111) in coherent equilibria were predicted to have half the solute concentration and three times the migration driving force of those perpendicular to (111). However, no correlation between solute concentration and boundary orientation was observed. Ambiguous and contradictory evidence for a relationship between solute concentration, boundary orientation, and migration rate was found. The self-stress state of a grain boundary in a solute diffusion field may be better modelled as hydrostatic rather than plane stress. Hydrostatic compression may interact with the boundary excess volume and cause a PV driving force for migration. Predictions based on coherent equilibrium at a surface have not been tested for that geometry in calcite; they should be tested before they are applied to grain boundaries.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

In situ nanoscale visualization of solvent effects on molecular crystal surfaces

CrystEngComm ◽  
2021 ◽  
Author(s):  
Mikkel Herzberg ◽  
Anders Støttrup Larsen ◽  
Tue Hassenkam ◽  
Anders Østergaard Madsen ◽  
Jukka Rantanen
Keyword(s):  
Solid Solution ◽  
Solvent Effects ◽  
Molecular Crystal ◽  
Rational Design ◽  
Molecular Level ◽  
Molecular Crystals ◽  
Crystal Surfaces ◽  
Solution Interface ◽  
Atomic Force

Solvents can dramatically affect molecular crystals. Obtaining favorable properties for these crystals requires rational design based on molecular level understanding of the solid-solution interface. Here we show how atomic force...

scholarly journals An In-Situ Reaction Route to Molecular Level Dispersed Bisimide and ZnO Nanorod Hybrids with Efficient Photo-Induced Charge Transfer

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Chunzheng Lv ◽  
Lirong He ◽  
Jiahong Tang ◽  
Feng Yang ◽  
Chuhong Zhang
Keyword(s):  
Charge Transfer ◽  
Electric Field ◽  
Self Assembly ◽  
Molecular Level ◽  
Surface Photovoltage ◽  
Zno Nanorod ◽  
In Situ Reaction ◽  
Perylene Bisimide ◽  
Induced Charge

AbstractAs an important photoconductive hybrid material, perylene/ZnO has attracted tremendous attention for photovoltaic-related applications, but generally faces a great challenge to design molecular level dispersed perylenes/ZnO nanohybrids due to easy phase separation between perylenes and ZnO nanocrystals. In this work, we reported an in-situ reaction method to prepare molecular level dispersed H-aggregates of perylene bisimide/ZnO nanorod hybrids. Surface photovoltage and electric field-induced surface photovoltage spectrum show that the photovoltage intensities of nanorod hybrids increased dramatically for 100 times compared with that of pristine perylene bisimide. The enhancement of photovoltage intensities resulting from two aspects: (1) the photo-generated electrons transfer from perylene bisimide to ZnO nanorod due to the electric field formed on the interface of perylene bisimide/ZnO; (2) the H-aggregates of perylene bisimide in ZnO nanorod composites, which is beneficial for photo-generated charge separation and transportation. The introduction of ordered self-assembly thiol-functionalized perylene-3,4,9,10-tetracarboxylic diimide (T-PTCDI)/ ZnO nanorod composites induces a significant improvement in incident photo-to-electron conversion efficiency. This work provides a novel mentality to boost photo-induced charge transfer efficiency, which brings new inspiration for the preparation of the highly efficient solar cell.

Crack Driving Force in Anisotropic Media due to Non-Elastic Deformation

2004 ◽  
Vol 261-263 ◽  
pp. 75-80
Author(s):  
G.H. Nie ◽  
H. Xu
Keyword(s):  
Elastic Deformation ◽  
Driving Force ◽  
Strain Energy ◽  
Elastic Stress ◽  
Complex Function ◽  
Crack Driving Force ◽  
Special Cases ◽  
Degree Of Anisotropy ◽  
Minimum Strain Energy ◽  
Orthotropic Media

In this paper elastic stress field in an elliptic inhomogeneity embedded in orthotropic media due to non-elastic deformation is determined by the complex function method and the principle of minimum strain energy. Two complex parameters are expressed in a general form, which covers all characterizations of the degree of anisotropy for any ideal orthotropic elastic body. The stress acting on the long side of ellipse can be considered as a crack driving force and applied in failure and fatigue analysis of composites. For some special cases, the resulting solutions will reduce to the known results.

scholarly journals Compartmentalization of membrane trafficking, glucose transport, glycolysis, actin, tubulin and the proteasome in the cytoplasmic droplet/Hermes body of epididymal sperm

Open Biology ◽  
2015 ◽  
Vol 5 (8) ◽  
pp. 150080 ◽  
Author(s):  
Catherine E. Au ◽  
Louis Hermo ◽  
Elliot Byrne ◽  
Jeffrey Smirle ◽  
Ali Fazel ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Glucose Transporter ◽  
Molecular Level ◽  
Mammalian Species ◽  
Cytoskeletal Proteins ◽  
Epididymal Sperm ◽  
Quantitative Electron Microscopy ◽  
Cytoplasmic Droplet ◽  
Germ Cell Differentiation

Discovered in 1909 by Retzius and described mainly by morphology, the cytoplasmic droplet of sperm (renamed here the Hermes body) is conserved among all mammalian species but largely undefined at the molecular level. Tandem mass spectrometry of the isolated Hermes body from rat epididymal sperm characterized 1511 proteins, 43 of which were localized to the structure in situ by light microscopy and two by quantitative electron microscopy localization. Glucose transporter 3 (GLUT-3) glycolytic enzymes, selected membrane traffic and cytoskeletal proteins were highly abundant and concentrated in the Hermes body. By electron microscope gold antibody labelling, the Golgi trafficking protein TMED7/p27 localized to unstacked flattened cisternae of the Hermes body, as did GLUT-3, the most abundant protein. Its biogenesis was deduced through the mapping of protein expression for all 43 proteins during male germ cell differentiation in the testis. It is at the terminal step 19 of spermiogenesis that the 43 characteristic proteins accumulated in the nascent Hermes body.

Study of scalable IBS nanopatterning mechanisms for III-V semiconductors using in-situ surface characterization

2011 ◽  
Vol 1354 ◽  
Author(s):  
Jean Paul Allain ◽  
Osman El-Atwani ◽  
Alex Cimaroli ◽  
Daniel L. Rokusek ◽  
Sami Ortoleva ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Surface Characterization ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Low Energy ◽  
Self Organization ◽  
Beam Parameter ◽  
Ion Beam Sputtering

ABSTRACTIon-beam sputtering (IBS) has been studied as a means for scalable, mask-less nanopatterning of surfaces. Patterning at the nanoscale has been achieved for numerous types of materials including: semiconductors, metals and insulators. Although much work has been focused on tailoring nanopatterning by systematic ion-beam parameter manipulation, limited work has addressed elucidating on the underlying mechanisms for self-organization of multi-component surfaces. In particular there has been little attention to correlate the surface chemistry variation during ion irradiation with the evolution of surface morphology and nanoscale self-organization. Moreover the role of surface impurities on patterning is not well known and characterization during the time-scale of modification remains challenging. This work summarizes an in-situ approach to characterize the evolution of surface chemistry during irradiation and its correlation to surface nanopatterning for a variety of multi-components surfaces. The work highlights the importance and role of surface impurities in nanopatterning of a surface during low-energy ion irradiation. In particular, it shows the importance of irradiation-driven mechanisms in GaSb(100) nanopatterning by low-energy ions and how the study of these systems can be impacted by oxide formation.

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