scholarly journals Particle Migration Phenomena Related to Hydromechanical Effects at Contact between Different Materials in Embankment Dams

10.5772/67785 ◽  
2017 ◽  
Author(s):  
Francesco Federico
Keyword(s):  
Particle Migration ◽  
Embankment Dams

scholarly journals Surface charge modulation of rifampicin-loaded PLA nanoparticles to improve antibiotic delivery in Staphylococcus aureus biofilms

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
David Da Costa ◽  
Chloé Exbrayat-Héritier ◽  
Basile Rambaud ◽  
Simon Megy ◽  
Raphaël Terreux ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Surface Charge ◽  
Treatment Efficacy ◽  
Particle Migration ◽  
Bacterial Biofilm ◽  
Poly Lactic Acid ◽  
Retention Capacity ◽  
The Impact ◽  
Positively Charged ◽  
Antibiotic Delivery

Abstract Background After the golden age of antibiotic discovery, bacterial infections still represent a major challenge for public health worldwide. The biofilm mode of growth is mostly responsible for chronic infections that current therapeutics fail to cure and it is well-established that novel strategies must be investigated. Particulate drug delivery systems are considered as a promising strategy to face issues related to antibiotic treatments in a biofilm context. Particularly, poly-lactic acid (PLA) nanoparticles present a great interest due to their ability to migrate into biofilms thanks to their submicronic size. However, questions still remain unresolved about their mode of action in biofilms depending on their surface properties. In the current study, we have investigated the impact of their surface charge, firstly on their behavior within a bacterial biofilm, and secondly on the antibiotic delivery and the treatment efficacy. Results Rifampicin-loaded PLA nanoparticles were synthetized by nanoprecipitation and characterized. A high and superficial loading of rifampicin, confirmed by an in silico simulation, enabled to deliver effective antibiotic doses with a two-phase release, appropriate for biofilm-associated treatments. These nanoparticles were functionalized with poly-l-lysine, a cationic peptide, by surface coating inducing charge reversal without altering the other physicochemical properties of these particles. Positively charged nanoparticles were able to interact stronger than negative ones with Staphylococcus aureus, under planktonic and biofilm modes of growth, leading to a slowed particle migration in the biofilm thickness and to an improved retention of these cationic particles in biofilms. While rifampicin was totally ineffective in biofilms after washing, the increased retention capacity of poly-l-lysine-coated rifampicin-loaded PLA nanoparticles has been associated with a better antibiotic efficacy than uncoated negatively charged ones. Conclusions Correlating the carrier retention capacity in biofilms with the treatment efficacy, positively charged rifampicin-loaded PLA nanoparticles are therefore proposed as an adapted and promising approach to improve antibiotic delivery in S. aureus biofilms.

scholarly journals Combined electrokinetic and shear flows control colloidal particle distribution across microchannel cross-sections

Soft Matter ◽  
2021 ◽  
Author(s):  
Varun Lochab ◽  
Shaurya Prakash
Keyword(s):  
Shear Flow ◽  
Cross Sections ◽  
Lift Force ◽  
Shear Flows ◽  
Colloidal Particle ◽  
Particle Distribution ◽  
Particle Migration ◽  
Flow Parameters

We quantify and investigate the effects of flow parameters on the extent of colloidal particle migration and the corresponding electrophoresis-induced lift force under combined electrokinetic and shear flow.

scholarly journals Electromagnetic profiling of Owena Dam, Southwestern Nigeria, using very-low-frequency radio fields

2016 ◽  
Vol 63 (4) ◽  
pp. 237-250 ◽  
Author(s):  
Cyril Okpoli ◽  
Raphael Tijani
Keyword(s):  
Low Frequency ◽  
Soil Mass ◽  
Internal Erosion ◽  
Dam Failure ◽  
Real Component ◽  
Southwestern Nigeria ◽  
Very Low Frequency ◽  
Embankment Dams ◽  
Fractured Zones ◽  
Basement Structures

AbstractVery low frequency (VLF) was used to assess variations in overburden composition, bedrock lithology and the concealed basement structures within the bedrock of Owena Dam in Igbara-Oke of the Precambrian Basement Complex of Southwestern Nigeria. Five VLF-electromagnetic (EM) traverses were occupied at 5 m intervals. The VLF normal and filtered real component anomalies identify major geological interfaces suspected to be faults/fractured zones. The points of crossover between the real and imaginary components delineate the fractured zones, which were identified as areas of possible seepage (piping and sloughing). The internal erosion (permeability) of soil mass eventually leads to the formation of an open conduit in the soil, which may lead to failure of the embankment/dam. The fractured zones are suspected to be present at all traverses. In total, 21 fractured zones were identified along the dam embankment, with the deepest occurrence at Traverse 5. These seepage zones cause heterogeneity in the subsurface composition, which could lead to dam failure. The result of the study suggests that VLF is an adequate method of monitoring seepages in embankment dams.

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