I’ve updated by 3D separations figure by using actual DLS sizes rather than the dimensions roughly obtained from crystal structures. I have run into a snag with reporting the data however – use sizes by intensity or sizes by number. The difference is due to the fact that the raw DLS data is from intensity,…
In the previous post, I discussed how we could evaluate the flux of molecules through the membrane and alluded that this method could be used similarly to our effective diffusion coefficient manner of evaluating membrane impact. Here are results of the full comparison. Standard setup: 15nm membrane, 1 hour time point, 1mm fluid wells, 5%…
In this post I take a look at the flux of molecules through the 1-D membrane simulations. I will then use this flux to compare to systems lacking a membrane. First off, how to find the flux. Inside the membrane, the Flux = -Dm dc/dx. Unfortunately this is extremely hard to calculate because of the…
To identify how much of an effect the membrane has on particular simulations, we originally came up with the idea of using a phenomenological effective diffusion to view the membrane impact (see this post). Here is the most up to date version of the figure, which was slotted for use in the simulated diffusion paper:…
Because of the disagreement between the experimental and simulation comparison in this post, I decided to take a look at the Sterlitech membranes using SEM. Barrett gave me a hand with all the images, and we tried to look at the edge for thickness and the pores for density/overlapping pores. In this first image, the…
In this post I will describe the use of the 3-D computational diffusion model as applied to separations with thick membranes. Experimental: Track etched membranes were trimmed to fit into round plastic sepcons and were sealed in the traditional way using an o-ring. 20uL of protein sample was pipetted inside the sepcon and 20uL of…
In the past couple of weeks I’ve tried a few more molecules to flesh out the experimental verification of the separations model. This is a quick update of the results. In the following figure, the blue line is the predicted sieving curve, the green line sieving given a no membrane/free diffusion situation, and the blue…
This is a draft of a figure I think I’d like to use in my upcoming paper about charge based separations (this paper will include the Bernhard data). I thought I’d post it here first to get some feedback. I’ll first discuss the figure and then outline the problems that I see. Panel a. shows…
Permeability was calculated with Dagan theory for membranes in this post. Pore processing was performed and r.mat files were run through the programs used to calculated permeability in submitted Science paper. No Carbonization Experimental: 591 ul/(min*PSI*cm^2) Theoretical: 801 ul/(min*PSI*cm^2) Carbonized (6.2 nm taken out of diameters) Experimental: 289 ul/(min*PSI*cm^2) Theoretical: 438 ul/(min*PSI*cm^2) It seems that there…
There has been some confusion lately with what we should name the compartments in diffusion. Here’s what I’ve come up with: Top/Compartment with initial sample: Retentate Bottom/Compartment to which things diffuse: Dialysate The original word we were using for dialysate, filtrate, implies an active process and was criticized by scientists at NAMS. While dialysate implies…