scholarly journals Detection of Exhaust Particulate Induced Blood Clotting Anomalies using Rheometric Techniques

2021 ◽  
Author(s):  
◽  
Rebecca Hudson
Keyword(s):  
Blood Clotting ◽  
Sol Gel ◽  
Oscillatory Shear ◽  
Gel Point ◽  
Small Amplitude Oscillatory Shear ◽  
Fibrin Gels ◽  
Blood Clots ◽  
Frequency Independent ◽  
Sol Gel Transition ◽  
The Impact

Characterisation of viscoelastic materials through exploitation of the frequency independent gel point (GP) can be used to study blood clotting anomalies. Information regarding the sol-gel transition can be obtained for gelling systems by employing small amplitude oscillatory shear (SAOS) measurements over a range of oscillatory shear frequencies. Analysis of the fractal dimension, , at the GP has previously been used as a biomarker for pathologies related to thromboembolic disease. This thesis investigates the potential adverse clotting characteristics induced by the presence of exhaust particulates using rheometric techniques. SAOS experiments conducted using a combined motor transducer (CMT) rheometer are susceptible to inertial artefacts at high frequencies, leading to potentially significant error in the reported GP. Herein, the development and evaluation of an enhanced rheometer inertia correction procedure (ERIC) is shown to allow valid GP data to be obtained post-acquisition at previously inaccessible frequencies. The potential impact of soot particulates on coagulation is likely to be small due to the weakly elastic gelling systems being studied, thus necessitating the use of the ERIC procedure to remove the presence of any inertial artefacts causing miscalculation of the GP. Fibrin gels were studied as model blood clots to assess the effects of the inclusion of soot particulates on the GP. The impact of the inclusion of increasing concentrations of soot solution on the GP proved inconclusive after the application of ERIC. However, in whole blood clots, the post-ERIC GP data indicated an increase in the density of the clot formed with increasing soot concentration, suggesting an elevated health risk as a possible result of interruption of the clotting cascade due to soot particulates.

Scaling Behaviour of the Viscoelastic Properties of a Biopolymer System Near the Gel Point

1989 ◽  
Vol 177 ◽  
Author(s):  
M. A. V. Axelos ◽  
M. Kolb
Keyword(s):  
Steady State ◽  
Percolation Theory ◽  
Viscoelastic Properties ◽  
Sol Gel ◽  
Oscillatory Shear ◽  
Gel Point ◽  
Rheological Measurements ◽  
Scaling Behaviour ◽  
Sol Gel Transition ◽  
Gel Transition

ABSTRACTRheological measurements have been performed on pectin-calcium systems close to the sol-gel transition. Two different experimental setups - steady state and oscillatory shear measurements - show scaling of the viscoelastic properties. The results of both types of measurements are consistent with each other and with scalar percolation theory.

Viscoelastic Properties of Ceria Gel

2005 ◽  
Vol 480-481 ◽  
pp. 355-360
Author(s):  
Nopphawan Phonthammachai ◽  
Morakot Rumruangwong ◽  
Sirirat Jitkanka ◽  
Erdogan Gulari ◽  
Alexander M. Jamieson ◽  
...  
Keyword(s):  
Sol Gel ◽  
Gelation Time ◽  
Viscoelastic Behavior ◽  
Molar Ratio ◽  
Strength Parameter ◽  
Gel Point ◽  
Rheological Measurement ◽  
S Parameter ◽  
Storage And Loss Moduli ◽  
Sol Gel Transition

The viscoelastic behavior of different ceria gelling systems prepared through sol-gel transition were investigated by the rheological measurement. The gelation time was observed by the frequency independence of tand, and increased with increasing acid:alkoxide molar ratio. At the gel point, both storage and loss moduli (G’µ wn, G” µ wn)exhibited a power law dependence of applied frequency with n’ = n” = n. The viscoelastic exponents and gel strength parameter were dependent on the composition of system. The increase in HCl:alkoxide molar ratio increased the n value while decreased the S parameter.

Sol-Gel Transition Kinetics of Konjac Glucomannan Dilute Solution by Fluorescence Technique

2011 ◽  
Vol 399-401 ◽  
pp. 1326-1329
Author(s):  
Dong Ying Xu ◽  
Zheng Fu Liao ◽  
Hui Wang
Keyword(s):  
Chemical Engineering ◽  
Drug Carrier ◽  
Sol Gel ◽  
Konjac Glucomannan ◽  
Gel Point ◽  
Pharmaceutical Chemical ◽  
Dilute Solution ◽  
Sol Gel Transition ◽  
Kinetics Of ◽  
Gel Transition

Konjac glucomannan (KGM) has been widely used in pharmaceutical, chemical engineering, food industry, drug carrier delivery, etc. The sol-gel transition kinetics of KGM dilute solution was studied by steady fluorescence spectroscopy in this article. The results showed that the gel point of KGM solutions depend on the concentration of KGM, pH value and temperature. The sol-gel phase transition activation energy, ΔE, was calculated to be 83.1 kJ/mol based on first reaction kinetic model.

Characterization of Rheological Property of Mucoadhesive Polymeric Sol-Gel in the Presence of Black Ginger Kaempferia parviflora Extract

2020 ◽  
Vol 859 ◽  
pp. 81-86
Author(s):  
Siriporn Taokaew ◽  
Nattanich Wattanaphraya ◽  
Worawut Kriangkrai
Keyword(s):  
Rheological Property ◽  
Sol Gel ◽  
Gel Strength ◽  
Herbal Extract ◽  
Local Drug Delivery ◽  
Major Influence ◽  
Gel Point ◽  
Ginger Extract ◽  
Eudragit E100 ◽  
Sol Gel Transition

The local drug delivery based on mucoadhesion is an effective medical treatment. The mucoadhesive property relies on the formulated gel having optimized rheology. The addition of the drug also showed a major influence towards the sol-gel transition. In this study, compositional effect of Eudragit E100® base polymer, various mucoadhesive polymers, and the black ginger extract on the rheological property of the formulated sol-gel was assessed. It was found that gelling point and gel strength could be tuned mainly based on the concentration of Eudragit E100 limited at 40% w/w due to the viscosity. At Eudragit E100 of 30% w/w, 0.5% w/w herbal extract, and 1%w/w polyvinyl alcohol, the solution reached the gel point at 286 s (tan δ=1) with the gel strength of 1 kPa (G’=G”). For all the formulated sol-gels, the rheological property became better (faster gelling point with the gel strength varying from 100-700 kPa at low strain) a simulated saliva environment.

scholarly journals The impact of fluctuations and correlations in droplet growth by collision-coalescence revisited. Part I: Numerical calculation of post-gel droplet size distribution

2016 ◽  
Author(s):  
Lester Alfonso ◽  
Graciela B. Raga
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Sol Gel ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Stochastic Simulation Algorithm ◽  
Droplet Growth ◽  
Sol Gel Transition ◽  
The Impact ◽  
Gel Transition

Abstract. The impact of stochastic fluctuations in cloud droplet growth is a matter of broad interest, since stochastic effects are one of the possible explanations of how cloud droplets cross the size-gap and form the raindrop embryos that trigger warm rain development in cumulus clouds. Most theoretical studies in this topic rely on the use of the kinetic collection equation, or the stochastic simulation algorithm (Gillespie 1975). However, the kinetic collection equation is a deterministic equation with no stochastic fluctuations. Moreover, the traditional calculations using the kinetic collection equation are not valid when the system undergoes a transition from a continuous distribution to a distribution plus a runaway raindrop embryo (known as the sol-gel transition). On the other hand, the stochastic simulation algorithm, although intrinsically stochastic, fails to reproduce adequately the large end of the droplet size distribution due to the huge number of realizations required. Therefore, the full stochastic description of cloud droplet growth must be obtained from the solution of the master equation for stochastic coalescence. In this study the master equation is used to calculate the evolution of the droplet size distribution after the sol-gel transition. These calculations show that after the formation of the raindrop embryo, the expected droplet mass distribution strongly differs from the results obtained with the kinetic collection equation. Furthermore, the low mass bins and bins from the gel fraction are strongly anti-correlated in the vicinity of the critical time, this being one of the possible explanations for the differences between the kinetic and stochastic approaches after the sol-gel transition. Calculations performed within the stochastic framework provide insight into the inability of explicit microphysics cloud models to explain the droplet spectral broadening observed in small, warm clouds.

scholarly journals The impact of fluctuations and correlations in droplet growth by collision-coalescence revisited. Part II: Observational evidence of gel formation in warm clouds

2019 ◽  
Author(s):  
Lester Alfonso ◽  
Graciela B. Raga ◽  
Darrel Baumgardner
Keyword(s):  
Early Stage ◽  
Sol Gel ◽  
Observational Evidence ◽  
Cloud Formation ◽  
Droplet Growth ◽  
Gel Formation ◽  
Cumulus Clouds ◽  
Warm Rain ◽  
Sol Gel Transition ◽  
The Impact

Abstract. In recent papers (Alfonso et al., 2013; Alfonso and Raga, 2017) the sol-gel transition was proposed as a mechanism for the formation of large droplets required to trigger warm rain development in cumulus clouds. In the context of cloud physics, gelation can be interpreted as the formation of the lucky droplet that grows by accretion of smaller droplets at a much faster rate than the rest of the population and becomes the embryo for raindrops. However, all the results in this area have been theoretical or simulation studies. The aim of this paper is to find some observational evidence of gel formation in clouds by analyzing the distribution of the largest droplet at an early stage of cloud formation, and to show that the mass of the gel (largest drop) is a mixture of a Gaussian and a Gumbel distributions, in accordance with the pseudo-critical clustering scenario described in Gruyer et al. (2013) for nuclear multi-fragmentation.

Rheological properties of functionalised thermosensitive copolymers for injectable applications in medicine

2012 ◽  
Vol 66 (10) ◽  
Author(s):  
Ivana Chamradová ◽  
Lucy Vojtová ◽  
Lenka Michlovská ◽  
Petr Poláček ◽  
Josef Jančář
Keyword(s):  
Rheological Properties ◽  
Sol Gel ◽  
Polymer Concentration ◽  
Test Tube ◽  
Poly Lactic Acid ◽  
Gel Point ◽  
Sol Gel Transition ◽  
Poly Ethylene ◽  
Lower Temperature ◽  
Gel Transition

AbstractFunctionalised triblock copolymers based on poly((lactic acid)-co-(glycolic acid)) and poly(ethylene glycol) (PLGA-PEG-PLGA) further modified with 3-methylenetetrahydrofuran-2,5-dione (itaconic anhydride; ITA) exhibited sol-gel transition induced by increasing temperature. Rheological properties of a series of ITA/PLGA-PEG-PLGA/ITA copolymer concentrations (6–24 mass %) in deionised Milli-Q water were studied by both the test tube inverting method (TTIM) and rheometer. The gel stiffness increased with the polymer concentration shifting the gel point of the copolymer to the lower temperature. The present study demonstrates that each method describes a sol-gel transition, but the combined method gives comprehensive information about changes in colour, viscosity, elastic and loss moduli. Characterisation of such a gel is necessary for its further use, in order to determine whether the material is appropriate as an injectable biomedical hydrogel.

scholarly journals Fractal Structure and Fractal Time in Silica Sol-Gels

1990 ◽  
Vol 180 ◽  
Author(s):  
James E. Martin ◽  
Jess Wilcoxon
Keyword(s):  
Light Scattering ◽  
Sol Gel ◽  
Silica Sol ◽  
Density Fluctuations ◽  
Gel Point ◽  
Decay Times ◽  
Fractal Time ◽  
Sol Gel Transition ◽  
Point Light ◽  
Gel Transition

ABSTRACTNear the gel point, light scattering studies of silica sol-gels reveal fractal clusters whose size diverges as a power law, in accord with the predictions of percolation theory. More surprising is the appearance of a fractal time description of the dynamics of these clusters. This novel dynamics has recently been revealed by quasielastic light scattering from the density fluctuations that occur at the sol-gel transition. Since the relaxation of fluctuations in these branched polymer systems is self-similar, decay processes occur on all time scales (fractal time), and average decay times diverge. An interpretation of this observation will be presented that relies on a length-scale-dependent viscosity and the geometrical self-similarity of the sol-gel transition. The scattering theory is extended to the calculation of time- and frequency-dependent viscoelastic properties, as well as mechanical properties such as the shear modulus, steady state creep compliance, and viscosity. The viscoelastic predictions are found to be in good agreement with experimental data.

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