Direct simulation of a permeable membrane

1990 ◽  
Vol 51 (11) ◽  
pp. 1051-1053 ◽  
Author(s):  
U. Brosa
Keyword(s):  
Direct Simulation ◽  
Permeable Membrane

Computational Experiments with Direct Simulation Quasi-Random Monte Carlo

2009 ◽  
Author(s):  
Jose Camberos ◽  
Robert Greendyke ◽  
Larry Lambe ◽  
Brook Bentley
Keyword(s):  
Monte Carlo ◽  
Computational Experiments ◽  
Direct Simulation

Removal of trichloroethylene and trichloroethane using a novel hollow-fibre gas-permeable membrane

2003 ◽  
Vol 3 (5-6) ◽  
pp. 67-72
Author(s):  
S. Takizawa ◽  
T. Win
Keyword(s):  
Boundary Layer ◽  
Flow Regime ◽  
Removal Efficiency ◽  
Residence Time ◽  
Flow Rate ◽  
Air Flow ◽  
Hollow Fibre ◽  
Permeation Rate ◽  
Permeable Membrane ◽  
Diffusional Boundary Layer

In order to evaluate effects of operational parameters on the removal efficiency of trichloroethylene and 1,1,1-trichloroethene from water, lab-scale experiments were conducted using a novel hollow-fibre gaspermeable membrane system, which has a very thin gas-permeable membrane held between microporous support membranes. The permeation rate of chlorinated hydrocarbons increased at higher temperature and water flow rate. On the other hand, the effects of the operational conditions in the permeate side were complex. When the permeate side was kept at low pressure without sweeping air (pervaporation), the removal efficiency of chlorinated hydrocarbon, as well as water permeation rate, was low probably due to lower level of membrane swelling on the permeate side. But when a very small amount of air was swept on the membrane (air perstripping) under a low pressure, it showed a higher efficiency than in any other conditions. Three factors affecting the permeation rate are: 1) reduction of diffusional boundary layer within the microporous support membrane, 2) air/vapour flow regime and short cutting, and 3) the extent of membrane swelling on the permeate side. A higher air flow, in general, reduces the diffusional boundary layer, but at the same time disrupts the flow regime, causes short cutting, and makes the membrane dryer. Due to these multiple effects on gas permeation, there is an optimum operational condition concerning the vacuum pressure and the air flow rate. Under the optimum operational condition, the residence time within the hollow-fibre membrane to achieve 99% removal of TCE was 5.25 minutes. The log (removal rate) was linearly correlated with the average hydraulic residence time within the membrane, and 1 mg/L of TCE can be reduced to 1 μg/L (99.9% removal).

Development, Evaluation and Optimization of Osmotic Controlled Tablets of Aceclofenac for Rheumatoid Arthritis Management

2019 ◽  
Vol 9 (1) ◽  
pp. 29-36
Author(s):  
Bijaya Ghosh ◽  
Niraj Mishra ◽  
Preeta Bose ◽  
Moumita D. Kirtania
Keyword(s):  
Rheumatoid Arthritis ◽  
Polyethylene Glycol ◽  
Sodium Chloride ◽  
Cellulose Acetate ◽  
Hydroxypropyl Methylcellulose ◽  
Release Profile ◽  
Polyethylene Glycol 400 ◽  
Permeable Membrane ◽  
Cumulative Release ◽  
The Core

Objective: Rheumatoid arthritis is a dreaded disease, characterized by pain, inflammation and stiffness of joints, leading to severe immobility problems. The disease shows circadian variation and usually gets aggravated in early morning hours. Aceclofenac, a BCS Class II compound is routinely used in the treatment of pain and inflammation associated with rheumatoid arthritis. The objective of this study was to develop an osmotic delivery system of Aceclofenac that after administration at bedtime would deliver the drug in the morning hours. </P><P> Methods: A series of osmotically controlled systems of aceclofenac was developed by using lactose, sodium chloride and hydroxypropyl methylcellulose K100M as osmogens. Cellulose acetate (2% w/v in acetone) with varying concentrations of polyethylene glycol-400 was used as the coating polymer to create semi permeable membrane and dissolution was carried out in 290 mOsm phosphate buffer. Formulation optimization was done from four considerations: cumulative release at the end of 6 hours (lag time), cumulative release at the end of 7 hours (burst time), steady state release rate and completeness of drug release. </P><P> Results: A formulation having swelling polymer hydroxypropyl methylcellulose in the core and lactose and sodium chloride as osmogens, polyethylene glycol-400 (16.39 %) as pore former, with a coating weight of 5% was a close fit to the target release profile and was chosen as the optimum formulation. Conclusion: Aceclofenac tablets containing lactose, HPMC and sodium chloride in the core, given a coating of cellulose acetate and PEG-400 (5% wt gain), generated a release profile for optimum management of rheumatoid arthritic pain.

Numerical Methods for the Kinetic Theory of Fluids

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Numerical Methods ◽  
Kinetic Theory ◽  
Computational Efficiency ◽  
Lattice Boltzmann ◽  
Direct Simulation Monte Carlo ◽  
Particle Methods ◽  
Direct Simulation ◽  
Simulation Monte Carlo

This chapter provides a bird’s eye view of the main numerical particle methods used in the kinetic theory of fluids, the main purpose being of locating Lattice Boltzmann in the broader context of computational kinetic theory. The leading numerical methods for dense and rarified fluids are Molecular Dynamics (MD) and Direct Simulation Monte Carlo (DSMC), respectively. These methods date of the mid 50s and 60s, respectively, and, ever since, they have undergone a series of impressive developments and refinements which have turned them in major tools of investigation, discovery and design. However, they are both very demanding on computational grounds, which motivates a ceaseless demand for new and improved variants aimed at enhancing their computational efficiency without losing physical fidelity and vice versa, enhance their physical fidelity without compromising computational viability.

Class I–unrestricted noncytotoxic anti–HTLV-I activity of CD8+ T cells

Blood ◽  
2000 ◽  
Vol 96 (5) ◽  
pp. 1994-1995 ◽  
Author(s):  
Masako Moriuchi ◽  
Hiroyuki Moriuchi
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Mononuclear Cells ◽  
Membrane Filter ◽  
Cd8 T Cell ◽  
Class I ◽  
Type I ◽  
Peripheral Blood Mononuclear ◽  
Permeable Membrane

Abstract Although it is widely believed that viral clearance is mediated principally by the destruction of infected cells by cytotoxic T cells, noncytolytic antiviral activity of CD8+ T cells may play a role in preventing the progression to disease in infections with immunodeficiency viruses and hepatitis B virus. We demonstrate here that (1) replication of human T-lymphotropic virus type I (HTLV-I) is more readily detected from CD8+ T-cell–depleted (CD8−) peripheral blood mononuclear cells (PBMCs) of healthy HTLV-I carriers than from unfractionated PBMCs, (2) cocultures of CD8− PBMCs with autologous or allogeneic CD8+ T cells suppressed HTLV-I replication, and (3) CD8+ T-cell anti-HTLV-I activity is not abrogated intrans-well cultures in which CD8+ cells are separated from CD8− PBMCs by a permeable membrane filter. These results suggest that class I-unrestricted noncytolytic anti–HTLV-I activity is mediated, at least in part by a soluble factor(s), and may play a role in the pathogenesis of HTLV-I infection.

scholarly journals The effect of ultrafiltration transmembrane permeation on the flow field in a surrogate system of an artificial kidney

2021 ◽  
Vol 2 ◽  
Author(s):  
Matilde De Pascale ◽  
Monica Faria ◽  
Cristiana Boi ◽  
Viriato Semiao ◽  
Maria Norberta de Pinho
Keyword(s):  
Pressure Drop ◽  
Artificial Kidney ◽  
Shear Stresses ◽  
Removal Rates ◽  
Permeable Membrane ◽  
Fluid Removal ◽  
Renal Replacement Therapies ◽  
Extracorporeal Blood Circulation ◽  
Conventional Hemodialysis ◽  
Upper Chamber

Abstract Renal Replacement Therapies generally associated to the Artificial Kidney (AK) are membrane-based treatments that assure the separation functions of the failing kidney in extracorporeal blood circulation. Their progress from conventional hemodialysis towards high-flux hemodialysis (HFHD) through the introduction of ultrafiltration membranes characterized by high convective permeation fluxes intensified the need of elucidating the effect of the membrane fluid removal rates on the increase of the potentially blood-traumatizing shear stresses developed adjacently to the membrane. The AK surrogate consisting of two-compartments separated by an ultrafiltration membrane is set to have water circulation in the upper chamber mimicking the blood flow rates and the membrane fluid removal rates typical of HFHD. Pressure drop mirrors the shear stresses quantification and the modification of the velocities profiles. The increase on pressure drop when comparing flows in slits with a permeable membrane and an impermeable wall is ca. 512% and 576% for $ \mathrm{CA}22/5\%{\mathrm{SiO}}_2 $ and $ \mathrm{CA}30/5\%{\mathrm{SiO}}_2 $ membranes, respectively.

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