Diffusion Limited Aggregation of PMMA Stereocomplex in Thin Films

2001 ◽  
Vol 710 ◽  
Author(s):  
Yves Grohens ◽  
Gilles Castelein ◽  
Pascal Carriere ◽  
Jiri Spevacek
Keyword(s):  
Aggregation Process ◽  
Diffusion Limited Aggregation ◽  
Force Microscopy ◽  
Cluster Aggregation ◽  
Diffusion Limited ◽  
Atomic Force ◽  
Slow Aggregation ◽  
Nanoscale Patterns ◽  
Surface Nature ◽  
Aggregation Phenomena

ABSTRACTThe nanoscale patterns formed by poly(methyl methacrylate) (PMMA) stereocomplexes at the surface of silicon wafers, glass and mica, were investigated by tapping mode atomic force microscopy (TM-AFM). The effects of the solvent nature, PMMA concentration, i/s-ratio (stoechimetry) and surface nature on the morphology of the stereocomplex thin layer at a surface were addressed. The aggregation phenomena are well described by the diffusion limited cluster-cluster aggregation model (DLA) and the fractal exponent D calculated. The i/s-ratio strongly influences the fractal exponent D which is equal to 1.35 for the 1:2 ratio is lower than for the other i:s ratios which are 1.46, 1.61, 1.82 for 1:1, 2:1 and 4:1 ratios, respectively. The low values of the fractal dimension D are indicative of a fast aggregation process and higher values of D correspond to a slow aggregation process.

scholarly journals Valorization of Apple Peels through the Study of the Effects on the Amyloid Aggregation Process of κ-Casein

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2371
Author(s):  
Valeria Guarrasi ◽  
Giacoma Cinzia Rappa ◽  
Maria Assunta Costa ◽  
Fabio Librizzi ◽  
Marco Raimondo ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Environmental Sustainability ◽  
Bovine Milk ◽  
Amyloid Formation ◽  
Aggregation Process ◽  
Amyloid Aggregation ◽  
Social Challenges ◽  
Force Microscopy ◽  
Atomic Force ◽  
Apple Peels

Waste valorization represents one of the main social challenges when promoting a circular economy and environmental sustainability. Here, we evaluated the effect of the polyphenols extracted from apple peels, normally disposed of as waste, on the amyloid aggregation process of κ-casein from bovine milk, a well-used amyloidogenic model system. The effect of the apple peel extract on protein aggregation was examined using a thioflavin T fluorescence assay, Congo red binding assay, circular dichroism, light scattering, and atomic force microscopy. We found that the phenolic extract from the peel of apples of the cultivar “Fuji”, cultivated in Sicily (Caltavuturo, Italy), inhibited κ-casein fibril formation in a dose-dependent way. In particular, we found that the extract significantly reduced the protein aggregation rate and inhibited the secondary structure reorganization that accompanies κ-casein amyloid formation. Protein-aggregated species resulting from the incubation of κ-casein in the presence of polyphenols under amyloid aggregation conditions were reduced in number and different in morphology.

Direct Measurement of Ion Beam Induced, Nanoscale Roughening of GaN

2005 ◽  
Vol 864 ◽  
Author(s):  
Bentao Cui ◽  
P. I. Cohen ◽  
A. M. Dabiran
Keyword(s):  
Ion Beam ◽  
High Energy ◽  
Surface Relaxation ◽  
Surface Roughening ◽  
High Energy Electron ◽  
Force Microscopy ◽  
Atomic Force ◽  
Continuum Equation ◽  
Argon Ions ◽  
Nanoscale Patterns

AbatractThe formation of ion induced nanoscale patterns such as ripple, dots or pores can be described by a linear continuum equation consisting of a surface roughening term due to curvature-dependent sputtering or asymmetric attachment of vacancies, and a surface smoothing term due to thermal or ion-induced diffusion. By studying ion-induced dimple volume change using atomic force microscopy, we show a method to measure the ion-roughening coefficient. Using this method, we found the roughening coefficient í was 45 nm2/sec at 730K for initial ion etchings with 300 eV Argon ions. Cathodoluminescence measurements indicated Ga-vacancy formation during ion bombardment. The activation energy for surface relaxation after ion etching was about 0.12 eV as measured by reflection high energy electron diffraction.

Concentration Influence on Diffusion Limited Cluster Aggregation

1994 ◽  
Vol 367 ◽  
Author(s):  
ST.C. Pencea ◽  
M. Dumitrascu
Keyword(s):  
Brownian Motion ◽  
Fractal Dimensions ◽  
Simple Random Walk ◽  
Two Dimensional ◽  
Diffusion Limited Aggregation ◽  
Dimensional Lattice ◽  
Cluster Aggregation ◽  
Box Counting ◽  
Diffusion Limited ◽  
Diffusion Limited Cluster Aggregation

AbstractDiffusion-limited cluster aggregation has been simulated on a square two dimensional lattice. In order to simulate the brownian motion, we used both the algorithm proposed initially by Kolb et all. and a new algorithm intermediary between a simple random walk and the ballistic model.The simulation was performed for many values of the concentration, from 1 to 50%. By using a box-counting algorithm one has calculated the fractal dimensions of the obtained clusters. Its increasing vs. concentration has been pointed out. The results were compared with those of the classical diffusion-limited aggregation (DLA).

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