Model for particle migration in bidisperse suspensions by use of effective temperature

Abstract From Gaia DR2 data of eight high-velocity hot post-AGB candidates, LS 3593, LSE 148, LS 5107, HD 172324, HD 214539, LS IV −12 111, LS III +52 24, and LS 3099, we found that six of them have accurate parallaxes which made it possible to derive their distances, absolute visual magnitudes (MV) and luminosity (log L/L⊙). All the stars except LS 5107 have an accurate effective temperature (Teff) in the literature. Some of these stars are metal poor, and some of them do not have circumstellar dust shells. In the past, the distances of some stars were estimated to be 6 kpc, which we find to be incorrect. The accurate Gaia DR2 parallaxes show that they are relatively nearby, post-AGB stars. When compared with post-AGB evolutionary tracks we find their initial masses to be in the range 1 M⊙ to 2 M⊙. We find the luminosity of LSE 148 to be significantly lower than that of post-AGB stars, suggesting that this is a post-horizontal-branch star or post-early-AGB star. LS 3593 and LS 5107 are new high-velocity hot post-AGB stars from Gaia DR2.

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The Remarkable Evolution of the Post-Agb Star FG SGE

Highlights of Astronomy ◽

10.1017/s1539299600021134 ◽

1998 ◽

Vol 11 (1) ◽

pp. 363-363

Author(s):

Johanna Jurcsik ◽

Benjamin Montesinos

Keyword(s):

Time Scales ◽

Effective Temperature ◽

Planetary Nebula ◽

Planetary Nebulae ◽

Central Star ◽

Evolutionary Models ◽

Single Star ◽

Line Intensities ◽

Evolutionary Changes ◽

Evolutionary Studies

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models. The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

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Electrophoretic slip-tuned particle migration in microchannel viscoelastic fluid flows

Physical Review Fluids ◽

10.1103/physrevfluids.3.074202 ◽

2018 ◽

Vol 3 (7) ◽

Cited By ~ 18

Author(s):

Di Li ◽

Xiangchun Xuan

Keyword(s):

Viscoelastic Fluid ◽

Fluid Flows ◽

Particle Migration

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

Journal of Nanobiotechnology ◽

10.1186/s12951-020-00760-w ◽

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.

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

Soft Matter ◽

10.1039/d0sm01646b ◽

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.

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