| 1. |
- Bergenholtz, Johan, 1964, et al.
(författare)
-
On-off dissociation dynamics of colloidal doublets
- 2013
-
Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 104:1
-
Tidskriftsartikel (refereegranskat)abstract
- First-passage time theory is used to analyze the dissociation behavior of doublets of colloidal particles. The first-passage time distribution for particles interacting via a DLVO potential is determined numerically. For strongly attractive particles the distribution becomes broad such that the mean first-passage time becomes a poor measure of the dynamics. In spite of this, use can be made of the mean in a matching condition, which allows for reproducing distributions for strongly attractive doublets by a semi-analytical solution for particles interacting only through surface adhesion. The smallest eigenvalue in the analytical solution, which governs the long-time asymptotic behavior of the first-passage time distribution, is identified analytically for strongly attractive pairs of particles. In addition, in this limit the distribution is shown to asymptote to an exponential distribution, which means that the dissociation process can be simply captured by an on-off model, without sacrificing the effect of the surface chemistry, with a constant probability for dissociation. This probability is simply related to the surface-adhesive parameter and the separation distance at which the pair of particles ceases to be considered a doublet.
|
|
| 2. |
- Gröning, Remigius, et al.
(författare)
-
Intravenous immunoglobulin therapy for COVID-19 in immunocompromised patients : A retrospective cohort study
- 2024
-
Ingår i: International Journal of Infectious Diseases. - : Elsevier. - 1201-9712 .- 1878-3511. ; 144
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate the effectiveness of intravenous immunoglobulin (IVIG) as treatment for COVID-19 in immunocompromised patients. Methods: This retrospective study investigated outcomes for immunocompromised, vaccine non-responsive, patients that between September 2022 and April 2023 received IVIG as treatment for COVID-19 in the region of Västerbotten, Sweden. We analyzed clinical data, viral load, and anti-SARS-CoV-2 IgG binding and neutralization levels of patient serum samples and IVIG production batches. Primary and secondary outcomes were clinical cure and viral clearance, respectively.Results: Sixteen patients were analyzed. After a median COVID-19 duration of 4 weeks, a median 60 g IVIG infusion increased SARS-CoV-2 binding and neutralizing antibody levels, with broad in vitro activity against tested variants. The treatment resulted in abrogation of viremia in all patients and general improvement in 15 survivors that all met the primary endpoint. Thirteen patients met the secondary endpoint at follow-up after a median of four months. Two subjects with persistent SARS-CoV-2 carriage relapsed but were successfully retreated with IVIG.Conclusions: Antibodies in IVIG efficiently neutralized several SARS-CoV-2 variants. Treatment with IVIG was associated with clinical cure and viral clearance in immunocompromised patients. Our data suggests that IVIG could be a novel treatment alternative for COVID-19 for this patient category.
|
|
| 3. |
- Kaunisto, Erik, 1982, et al.
(författare)
-
A simple model for simulation of particle deaggregation of few-particle aggregates
- 2014
-
Ingår i: AIChE Journal. - : Wiley. - 0001-1541 .- 1547-5905. ; 60:5, s. 1863-1869
-
Tidskriftsartikel (refereegranskat)abstract
- A proper mechanistic understanding of the deaggregation process of small colloidal particle aggregates is of generic importance within many fields of science and engineering. The methodology for modeling colloidal deaggregation is currently limited to analytical solutions in the two-particle case and time consuming numerical algorithms, such as Brownian Dynamics (BD) simulations, for many-particle aggregates. To address this issue, a simplified alternative model that describes deaggregation of few-particle aggregates is presented. The model includes end-particle deaggregation and a particle reconfiguration mechanism, which are the two most important mechanisms for deaggregation. Comparison of the calculated first passage time distribution for various two-, three-, four-, and five-particle aggregates with the corresponding result using BD simulations confirms the validity of the model. It is concluded that the dominating mechanism behind deaggregation can be quantified using a deaggregation number, which reflects the time scale for reconfiguration relative to the time scale for end-particle deaggregation.
|
|
| 4. |
- Nohlert, Johan, 1987, et al.
(författare)
-
Global monitoring of fluidized-bed processes by means of microwave cavity resonances
- 2014
-
Ingår i: Measurement: Journal of the International Measurement Confederation. - : Elsevier BV. - 0263-2241. ; 55, s. 520-535
-
Tidskriftsartikel (refereegranskat)abstract
- We present an electromagnetic measurement system for monitoring of the effective permittivity in closed metal vessels, which are commonly used in the process industry. The measurement system exploits the process vessel as a microwave cavity resonator and the relative change in its complex resonance frequencies is related to the complex effective permittivity inside the vessel. Also, thermal expansion of the process vessel is taken into account and we compensate for its influence on the resonance frequencies by means of a priori information derived from a set of temperature measurements. The sensitivities, that relate the process state to the measured resonance frequencies, are computed by means of a detailed finite element model. The usefulness of the proposed measurement system is successfully demonstrated for a pharmaceutical fluidized-bed process, where the water and solid contents inside the process vessel is of interest.
|
|
| 5. |
- Wiklund, Johan A., et al.
(författare)
-
A comparative study of UVP and LDA techniques for pulp suspensions in pipe flow
- 2006
-
Ingår i: AIChE Journal. - : Wiley. - 0001-1541 .- 1547-5905. ; 52:2, s. 484-495
-
Tidskriftsartikel (refereegranskat)abstract
- For the first time, noninvasive measurements in pulp suspensions at consistencies ranging from 0.74%(w/w) up to 7.8%(w/w) have been performed simultaneously using ultrasound velocity profiling (UVP) and laser doppler anemometry (LDA) in an experimental pipe flow loop. Results show that both techniques can be used to determine the plug flow velocity with good agreement in much more concentrated pulp suspensions than what has been reported so far in the literature. Instantaneous velocity profiles have been obtained noninvasively in pipe flow using the UVP technique, and it is shown that combined with simultaneous pressure drop measurements, the UVP technique can be used to determine the yield stress in-line. Results further show that LDA works, with limited penetration depth of up to several millimeters, even in strongly opaque systems, such as in 7.8%(w/w) pulp. Deviating results were however obtained in the near wall region and more work is needed.
|
|
| 6. |
|
|
| 7. |
- Claesson, Julia, 1985, et al.
(författare)
-
Measurement and Analysis of Flow of Concentrated Fiber Suspensions through a 2-D Sudden Expansion Using UVP
- 2013
-
Ingår i: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 59:3, s. 1012-1021
-
Tidskriftsartikel (refereegranskat)abstract
- The ultrasound velocity profiling technique (UVP) was used to study flow structures after a two-dimensional (2-D) 1: 11 sudden expansion of pulp fiber suspensions at varied average velocities (1-2.2 m/s) and concentrations (1.8 and 2.8 wt %). One advantage of studying jet geometry is the potential to investigate the main flow structures away from walls. Measurements done at the same percent of the total jet length, at constant concentration, show that an increase in flow rate gave a faster decrease in centerline velocity and a quicker increase in jet width. Increasing the concentration, at the same jet length, the centerline velocity was more stable and the width of the mixing layer increased more rapidly. Comparisons with CFD simulations in the laminar regime, using the Bingham plastic model, show that the main flow structures were captured if the yield stress used in the simulations is approximately 20% of the measured using a rheometer.
|
|
| 8. |
|
|
| 9. |
- Darelius, Anders, 1977, et al.
(författare)
-
Fluid dynamics simulation of the high shear mixing process
- 2010
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 164:2-3, s. 418-424
-
Tidskriftsartikel (refereegranskat)abstract
- The Eulerian-Eulerian two-fluid approach for modelling multiphase flows is used to simulate the flow in a high shear mixer. The results are compared with experimental velocity profiles for the solids phase at the wall in the mixer obtained using a high speed camera (Darelius et al. Chem. Eng. Sci. 62 (2007) 2366).The governing equations are closed using relations from the Kinetic Theory of Granular Flow (KTGF) combined with a frictional stress model due to Johnson and Jackson and Schaeffer and inter-phase drag due to Wen and Yu. In addition, calculations are presented for a model with a constant particle phase viscosity (CPV). Free slip and partial slip boundary conditions for the solid phase velocity at the vessel wall and the impeller have been utilized.The results show that the bed height could be well predicted by the partial slip model, whereas the free slip model could not capture the experimentally found bed height satisfactorily. For the KTGF model, the swirling motion of the rotating torus that is formed by the moving powder bed was over-predicted and the tangential wall velocity was under-predicted, probably due to the fact that the frictional stress model needs to be further developed, e.g. to tackle cohesive particles in dense flow. The CPV model gave predictions in good agreement with the experiments for a solids viscosity of 0.1. Pa. s and a wall slip parameter of 0.005. m/Pa. s. However, for a very low or very high value of the particle phase viscosity and for a high value of the wall slip parameter the agreement with experiments was poor. Interestingly, values of the viscosity that are commonly employed for fluidized beds seem applicable also in the present case. © 2009 Elsevier B.V.
|
|
| 10. |
- Eidevåg, Tobias, 1987, et al.
(författare)
-
Angle of repose of snow: An experimental study on cohesive properties
- 2022
-
Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 194
-
Tidskriftsartikel (refereegranskat)abstract
- The angle of repose is a measure reflecting the internal friction and cohesion properties of a granular material. In this paper, we present an experimental setup and measurements for the angle of repose of snow for seven different snow samples over a large range of temperatures. The results show that the angle of repose is dependent on the fall height, the temperature, and the grain size of the snow. These variables are quantified, and their interdependencies are separately studied. With increased snow temperature, the angle of repose increases, and this can be explained by the presence of a liquid layer on ice that can be thermodynamically stable at temperatures below the melting point of water. With decreasing grain size the angle of repose also increases which is expected since the cohesive energy decreases more slowly than the grain mass. For increasing fall height, the snow grains generally accelerate to larger collisional velocities, yielding a smaller angle of repose. In general, the dimensionless cohesion number was found to largely reflect the dependencies of the variables and is therefore useful for understanding what affects the angle of repose. The results demonstrate that the drag force and collision dynamics of ice grains are important for understanding how snow accumulates on a surface, for example if one desires predicting snow accretion by simulating a dispersed cloud of snow. © 2021
|
|
