scholarly journals Effect of Polymer Demixed Nanotopographies on Bacterial Adhesion and Biofilm Formation

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1921
Author(s):  
George Fleming ◽  
Jenny Aveyard ◽  
Joanne L. Fothergill ◽  
Fiona McBride ◽  
Rasmita Raval ◽  
...  
Keyword(s):  
Lower Surface ◽  
Surface Feature ◽  
Polymer Interface ◽  
Cell Counts ◽  
Binary Polymer ◽  
Lower Solubility ◽  
Specific Morphology ◽  
Discrete Surface ◽  
Global Threat ◽  
Lower Surface Energy

As the current global threat of antimicrobial resistance (AMR) persists, developing alternatives to antibiotics that are less susceptible to resistance is becoming an urgent necessity. Recent advances in biomaterials have allowed for the development and fabrication of materials with discrete surface nanotopographies that can deter bacteria from adhering to their surface. Using binary polymer blends of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL) and varying their relative concentrations, PS/PCL, PS/PMMA and PCL/PMMA polymer demixed thin films were developed with nanoisland, nanoribbon and nanopit topographies. In the PS/PCL system, PS segregates to the air-polymer interface, with the lower solubility PCL preferring the substrate-polymer interface. In the PS/PMMA and PCL/PMMA systems, PMMA prefers the air-polymer interface due to its greater solubility and lower surface energy. The anti-adhesion efficacy of the demixed films were tested against Pseudomonas aeruginosa (PA14). PS/PCL and PCL/PMMA demixed films showed a significant reduction in cell counts adhered on their surfaces compared to pure polymer control films, while no reduction was observed in the counts adhered on PS/PMMA demixed films. While the specific morphology did not affect the adhesion, a relationship between bacterial cell and topographical surface feature size was apparent. If the surface feature was smaller than the cell, then an anti-adhesion effect was observed; if the surface feature was larger than the cell, then the bacteria preferred to adhere.

scholarly journals The effects of morphological variation and polymer/polymer interface on the tensile modulus of binary polymer blends: a modeling approach

2020 ◽  
Vol 41 (2) ◽  
pp. 109-118
Author(s):  
Esmail Sharifzadeh ◽  
Yasahr Amiri
Keyword(s):  
Polymer Blends ◽  
Morphological Variation ◽  
Tensile Modulus ◽  
Network System ◽  
Test Results ◽  
Model Accuracy ◽  
Acceptable Accuracy ◽  
Polymer Interface ◽  
Binary Polymer ◽  
Neural Network System

Abstract In this work, the effects of the morphological variation and the polymer/polymer interface on the tensile modulus of binary polymer blends were evaluated using a combined modeling method. The characteristics of the polymer/polymer interface region were evaluated using a neural network system and the results were used to improve the analytical model. The model accuracy was investigated by comparing its predictions with the tensile test results of some prepared iPP/PA blend samples and also some other data from literature which revealed an acceptable accuracy (error < 5%).

Vapor sorption in binary polymer brushes: The effect of the polymer–polymer interface

2021 ◽  
Vol 155 (5) ◽  
pp. 054904
Author(s):  
Leon A. Smook ◽  
Guido C. Ritsema van Eck ◽  
Sissi de Beer
Keyword(s):  
Polymer Brushes ◽  
Vapor Sorption ◽  
Polymer Interface ◽  
Binary Polymer ◽  
Binary Polymer Brushes

Molecular Dynamics Studies of Surface Nucleation and Crystal Growth of Si on SiO2 Substrates

2005 ◽  
Vol 899 ◽  
Author(s):  
Byoung-Min Lee ◽  
Hong Koo Baik ◽  
Takahide Kuranaga ◽  
Shinji Munetoh ◽  
Teruaki Motooka
Keyword(s):  
Thin Film ◽  
Molecular Dynamics ◽  
Crystal Growth ◽  
Surface Energy ◽  
Md Simulations ◽  
Lower Surface ◽  
Surface Nucleation ◽  
Lower Surface Energy ◽  
Potential Parameters ◽  
Si Thin Film

AbstractMolecular dynamics (MD) simulations of atomistic processes of nucleation and crystal growth of silicon (Si) on SiO2 substrate have been performed using the Tersoff potential based on a combination of Langevin and Newton equations. A new set of potential parameters was used to calculate the interatomic forces of Si and oxygen (O) atoms. It was found that the (111) plane of the Si nuclei formed at the surface was predominantly parallel to the surface of MD cell. The values surface energy for (100), (110), and (111) planes of Si at 77 K were calculated to be 2.27, 1.52, and 1.20 J/m2, respectively. This result suggests that, the nucleation leads to a preferred (111) orientation in the poly-Si thin film at the surface, driven by the lower surface energy.

Control of Primary Particle Size and the Onset of Aggregate Formation: The Effect of Energy Release in Nanoparticle Collision and Coalescence Processes

2002 ◽  
Vol 731 ◽  
Author(s):  
Karl E.J. Lehtinen ◽  
Michael R. Zachariah
Keyword(s):  
Heat Transfer ◽  
Heat Release ◽  
Energy Release ◽  
Primary Particle ◽  
High Volume ◽  
Lower Surface ◽  
Aggregate Formation ◽  
Gas Temperature ◽  
Insufficient Time ◽  
Lower Surface Energy

AbstractDuring coalescence, the surface area of the particle decreases, resulting in a heat release associated with the resulting lower surface energy. In a growth process particle heating competes with heat transfer by conduction to the cooler carrier gas and radiation. This temperature increase can be extremely important and should be accounted for when modeling collision/coalescence processes. The heat release associated with particle coalescence may reduce the coalescence time by as much as a few orders of magnitude. In addition, under some conditions there is insufficient time for the particles to cool to the gas temperature before another collision event takes place. It is shown that accounting for energy release and heat transfer effects have a dramatic effect on primary particle formation and the onset of aggregate formation. The results of the work indicate that to grow the largest primary particles one should operate at low pressures and high volume loadings.

scholarly journals Thermodynamics of manganese oxides: Sodium, potassium, and calcium birnessite and cryptomelane

2017 ◽  
Vol 114 (7) ◽  
pp. E1046-E1053 ◽  
Author(s):  
Nancy Birkner ◽  
Alexandra Navrotsky
Keyword(s):  
Surface Energy ◽  
Surface Area ◽  
Oxidation State ◽  
Manganese Oxides ◽  
Lower Surface ◽  
Surface Energies ◽  
Surface Areas ◽  
Bulk Thermodynamics ◽  
Lower Surface Energy

Manganese oxides with layer and tunnel structures occur widely in nature and inspire technological applications. Having variable compositions, these structures often are found as small particles (nanophases). This study explores, using experimental thermochemistry, the role of composition, oxidation state, structure, and surface energy in the their thermodynamic stability. The measured surface energies of cryptomelane, sodium birnessite, potassium birnessite and calcium birnessite are all significantly lower than those of binary manganese oxides (Mn3O4, Mn2O3, and MnO2), consistent with added stabilization of the layer and tunnel structures at the nanoscale. Surface energies generally decrease with decreasing average manganese oxidation state. A stabilizing enthalpy contribution arises from increasing counter-cation content. The formation of cryptomelane from birnessite in contact with aqueous solution is favored by the removal of ions from the layered phase. At large surface area, surface-energy differences make cryptomelane formation thermodynamically less favorable than birnessite formation. In contrast, at small to moderate surface areas, bulk thermodynamics and the energetics of the aqueous phase drive cryptomelane formation from birnessite, perhaps aided by oxidation-state differences. Transformation among birnessite phases of increasing surface area favors compositions with lower surface energy. These quantitative thermodynamic findings explain and support qualitative observations of phase-transformation patterns gathered from natural and synthetic manganese oxides.

Bulk and (001) Surface Properties of TiAl3 Compound

2011 ◽  
Vol 299-300 ◽  
pp. 417-421
Author(s):  
Li Wang ◽  
Jian Hong Gong ◽  
Jun Gao
Keyword(s):  
Surface Energy ◽  
Structural Relaxation ◽  
Density Functional ◽  
Dominant Role ◽  
Lower Surface ◽  
Heat Of Formation ◽  
Lattice Constants ◽  
Structural And Electronic Properties ◽  
The Stability ◽  
Lower Surface Energy

The structural and electronic properties of bulk and (001) surface of TiAl3 have been examined by the first-principles total-energy pseudopotential method based on density functional theory. The lattice constants and heat of formation of bulk TiAl3 we obtained are in good agreement with the experimental and other theoretical values. The calculated bulk properties indicates that bonding nature in TiAl3 is a combination of metallic and ionic, in which the metallic bonding become the predominate one. the strongest hybridization exist in the DO22 structure, the Al-3p and Ti-3d bonding of TiAl3 play the dominant role in hybridization. The structural relaxation and surface energy for (001) slab have been simulated to make sure the stability of slabs with different atomic layers. Compared to TiB2 (0001) slab, TiAl3 surfaces shows smaller structural relaxation and lower surface energy, furthermore, the charge redistribution of (001) slab shows almost the same characteristics as bulk TiAl3, which confirms structural stability of TiAl3 with (001) slab. This present work makes a beneficial attempt at exploring TiAl3 surface as an ab initio method for studying possible nucleation mechanism of Aluminum on it.

Relationship Between Platelet Adhesion And Free Energies At Solid-Liquid Interfaces

1981 ◽  
Author(s):  
Donald J L McIver ◽  
Samuel Schürch
Keyword(s):  
Thrombus Formation ◽  
Lower Surface ◽  
Liquid Interfaces ◽  
Free Energies ◽  
Surface Wetting ◽  
Interfacial Energies ◽  
Synthetic Coating ◽  
Foreign Surface ◽  
Solid Liquid ◽  
Lower Surface Energy

Surface induced thrombosis remains an obstacle to extra-corpeal circulation and invasive investigation and therapy of the cardiovascular system. Although the molecular details of the blood-foreign surface interaction remain incompletely understood, from a thermodynamic viewpoint, thrombosis can only occur if thrombus formation lowers the free energy of the blood-surface system. We have recently reported a method of estimating surface free energies under physiological conditions from measurements of surface wetting by polar hydrophobic fluids. Here we report a correlation between interfacial energies and platelet retention on natural and artificial surfaces, and the effects on platelet retention of a synthetic coating developed in an attempt to mimic the thromboresistance of healthy endothelium. This coating has a lower surface energy than the artery and it appears to be equally thromboresistant.

scholarly journals The energy components of stacked chromatin layers explain the morphology, dimensions and mechanical properties of metaphase chromosomes

2014 ◽  
Vol 11 (92) ◽  
pp. 20131043 ◽  
Author(s):  
Joan-Ramon Daban
Keyword(s):  
Surface Potential ◽  
Experimental Studies ◽  
Lower Surface ◽  
Large Chromosome ◽  
Metaphase Chromosomes ◽  
Irregular Surfaces ◽  
Similar Shape ◽  
Work Up ◽  
Lower Surface Energy ◽  
Energy Components

The measurement of the dimensions of metaphase chromosomes in different animal and plant karyotypes prepared in different laboratories indicates that chromatids have a great variety of sizes which are dependent on the amount of DNA that they contain. However, all chromatids are elongated cylinders that have relatively similar shape proportions (length to diameter ratio approx. 13). To explain this geometry, it is considered that chromosomes are self-organizing structures formed by stacked layers of planar chromatin and that the energy of nucleosome–nucleosome interactions between chromatin layers inside the chromatid is approximately 3.6 × 10 −20 J per nucleosome, which is the value reported by other authors for internucleosome interactions in chromatin fibres. Nucleosomes in the periphery of the chromatid are in contact with the medium; they cannot fully interact with bulk chromatin within layers and this generates a surface potential that destabilizes the structure. Chromatids are smooth cylinders because this morphology has a lower surface energy than structures having irregular surfaces. The elongated shape of chromatids can be explained if the destabilizing surface potential is higher in the telomeres (approx. 0.16 mJ m −2 ) than in the lateral surface (approx. 0.012 mJ m −2 ). The results obtained by other authors in experimental studies of chromosome mechanics have been used to test the proposed supramolecular structure. It is demonstrated quantitatively that internucleosome interactions between chromatin layers can justify the work required for elastic chromosome stretching (approx. 0.1 pJ for large chromosomes). The high amount of work (up to approx. 10 pJ) required for large chromosome extensions is probably absorbed by chromatin layers through a mechanism involving nucleosome unwrapping.

AN UNEXPECTED SURFACE SEGREGATION PHENOMENON OF GOLD ON THE SURFACE OF A Pb(Au) SOLID SOLUTION

1997 ◽  
Vol 04 (06) ◽  
pp. 1139-1141 ◽  
Author(s):  
H. OUGHADDOU ◽  
B. AUFRAY ◽  
J. P. BIBÉRIAN ◽  
J. BERNARDINI
Keyword(s):  
Solid Solution ◽  
Chemical Composition ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Surface Segregation ◽  
Lower Surface ◽  
Surface Equilibrium ◽  
Segregation Phenomenon ◽  
Lower Surface Energy ◽  
Equilibrium Segregation

At 260°C, at the surface of a lead–gold (96·10-6 at/at) solid solution we observe by Auger electron spectroscopy an unexpected surface equilibrium segregation of gold. A quantitative evaluation of the Auger data obtained at the end of the segregation kinetics shows that the segregation of gold is consistent with the formation of a surface alloy with a chemical composition close to AuPb 3, with gold atoms situated under a layer of lead. We propose that this unusual segregation is related to the lower surface energy of this intermetallic compound AuPb 3 compared to the gold and lead ones.

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