scholarly journals Enhanced diffusion of tracer particles in dilute bacterial suspensions

Soft Matter ◽  
2014 ◽  
Vol 10 (16) ◽  
pp. 2748 ◽  
Author(s):  
Alexander Morozov ◽  
Davide Marenduzzo
Keyword(s):  
Enhanced Diffusion ◽  
Tracer Particles

scholarly journals Stirring by periodic arrays of microswimmers

2016 ◽  
Vol 811 ◽  
pp. 487-498 ◽  
Author(s):  
Joost de Graaf ◽  
Joakim Stenhammar
Keyword(s):  
Theoretical Work ◽  
Difficult Problem ◽  
Hydrodynamic Interactions ◽  
Bulk Fluid ◽  
Enhanced Diffusion ◽  
Periodic Arrays ◽  
Ewald Sum ◽  
Tracer Particles ◽  
Micro Organisms ◽  
New Strategies

The interaction between swimming micro-organisms or artificial self-propelled colloids and passive (tracer) particles in a fluid leads to enhanced diffusion of the tracers. This enhancement has attracted strong interest, as it could lead to new strategies to tackle the difficult problem of mixing on a microfluidic scale. Most of the theoretical work on this topic has focused on hydrodynamic interactions between the tracers and swimmers in a bulk fluid. However, in simulations, periodic boundary conditions (PBCs) are often imposed on the sample and the fluid. Here, we theoretically analyse the effect of PBCs on the hydrodynamic interactions between tracer particles and microswimmers. We formulate an Ewald sum for the leading-order stresslet singularity produced by a swimmer to probe the effect of PBCs on tracer trajectories. We find that introducing periodicity into the system has a surprisingly significant effect, even for relatively small swimmer–tracer separations. We also find that the bulk limit is only reached for very large system sizes, which are challenging to simulate with most hydrodynamic solvers.

Ion Beam Mixing of Ni-Ti Bilayered Thin Films

1985 ◽  
Vol 43 ◽  
pp. 290-291
Author(s):  
A. K. Rai ◽  
R. S. Bhattacharya ◽  
M. H. Rashid
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Amorphous Alloys ◽  
Ion Beam ◽  
Ion Bombardment ◽  
High Energy ◽  
Mixing Efficiency ◽  
Ion Beam Mixing ◽  
Enhanced Diffusion ◽  
Binary Metal

Ion beam mixing has recently been found to be an effective method of producing amorphous alloys in the binary metal systems where the two original constituent metals are of different crystal structure. The mechanism of ion beam mixing are not well understood yet. Several mechanisms have been proposed to account for the observed mixing phenomena. The first mechanism is enhanced diffusion due to defects created by the incoming ions. Second is the cascade mixing mechanism for which the kinematicel collisional models exist in the literature. Third mechanism is thermal spikes. In the present work we have studied the mixing efficiency and ion beam induced amorphisation of Ni-Ti system under high energy ion bombardment and the results are compared with collisional models. We have employed plan and x-sectional veiw TEM and RBS techniques in the present work.

Effects of Concurrent Co or Ti Silicidation on Transient Diffusion and End-of-Range Damage in Phosphorus Implanted Silicon

1992 ◽  
Vol 262 ◽  
Author(s):  
J.W. Honeycutt ◽  
J. Ravi ◽  
G. A. Rozgonyi
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Complete Removal ◽  
Dislocation Loops ◽  
Enhanced Diffusion ◽  
Depth Profiles ◽  
Enhanced Dissolution ◽  
Implantation Damage ◽  
Transmission Electron ◽  
Defect Behavior ◽  
Secondary Ion

ABSTRACTThe effects of Ti and Co silicidation on P+ ion implantation damage in Si have been investigated. After silicidation of unannealed 40 keV, 2×1015 cm-2 P+ implanted junctions by rapid thermal annealing at 900°C for 10–300 seconds, secondary ion mass spectrometry depth profiles of phosphorus in suicided and non-silicided junctions were compared. While non-silicided and TiSi2 suicided junctions exhibited equal amounts of transient enhanced diffusion behavior, the junction depths under COSi2 were significantly shallower. End-of-range interstitial dislocation loops in the same suicided and non-silicided junctions were studied by planview transmission electron microscopy. The loops were found to be stable after 900°C, 5 minute annealing in non-silicided material, and their formation was only slightly effected by TiSi2 or COSi2 silicidation. However, enhanced dissolution of the loops was observed under both TiSi2 and COSi2, with essentially complete removal of the defects under COSi2 after 5 minutes at 900°C. The observed diffusion and defect behavior strongly suggest that implantation damage induced excess interstitial concentrations are significantly reduced by the formation and presence of COSi2, and to a lesser extent by TiSi2. The observed time-dependent defect removal under the suicide films suggests that vacancy injection and/or interstitial absorption by the suicide film continues long after the suicide chemical reaction is complete.

scholarly journals Direction-dependent turning leads to anisotropic diffusion and persistence

2021 ◽  
pp. 1-37
Author(s):  
N. LOY ◽  
T. HILLEN ◽  
K. J. PAINTER
Keyword(s):  
Anisotropic Diffusion ◽  
Cell Movement ◽  
Orientation Dependence ◽  
Transport Equations ◽  
Heterogeneous Environment ◽  
Enhanced Diffusion ◽  
Mesoscopic Level

Cells and organisms follow aligned structures in their environment, a process that can generate persistent migration paths. Kinetic transport equations are a popular modelling tool for describing biological movements at the mesoscopic level, yet their formulations usually assume a constant turning rate. Here we relax this simplification, extending to include a turning rate that varies according to the anisotropy of a heterogeneous environment. We extend known methods of parabolic and hyperbolic scaling and apply the results to cell movement on micropatterned domains. We show that inclusion of orientation dependence in the turning rate can lead to persistence of motion in an otherwise fully symmetric environment and generate enhanced diffusion in structured domains.

Blocky Sb/C Anodes with Enhanced Diffusion Kinetics for High‐Rate and Ultra‐Long Cyclability Sodium Dual‐Ion Batteries

2021 ◽  
Author(s):  
Hong-Ji Li ◽  
Jing-Jing Li ◽  
Zhe Chen ◽  
Zhen-Zhen Wang ◽  
Jin Qu ◽  
...  
Keyword(s):  
High Rate ◽  
Diffusion Kinetics ◽  
Enhanced Diffusion
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