Continuous queries for Sandhya's part of the course by

The model answer for the W3_BAL_Worked Example 3.6 is very heavily biological focused with lots of technical detail about the liver - would we be expected to produce this level of biology understanding in the exam? (primarily talking about the second and third paragraph of the answer)

2022-10-18 21:11:16 UTC

In 7.4 Single Compartmental Model example, the system is modelled as a PFR. Could you explain this a little more, as I would not have thought a PFR would be suitable for modelling beads?

2022-10-31 09:04:20 UTC

ELAD Question 1

2022-11-10 10:30:45 UTC

The ELAD features a cell filter just before the treated plasma rejoins the separated blood cells to be fed back to the patient. Is this filter to capture any cells that have broken through from the HFB?

ELAD Question 2

2022-11-10 10:33:43 UTC

Is the purpose of the ELAD nutrient cycle (with a dextrose pump, oxygenator and heat exchanger etc.) to feed the hepatocyte cells in the HFB and keep them growing with the nutrients they need, and/or to enrich the plasma that will re-enter the patient?

FBB Question

2022-11-10 11:18:50 UTC

One of the advantages of a FBB is cells can be adherent or non-adherent. I thought cells were immobilised on solid particles in a FBB (and this is what keeps them separate to protect them from shear and improve mass transfer), so how can cells be non-adhered?

Hi Sandhya, with regards to attachment kinetics, are we required to memorise only the final equations relating everything together, or do we need to also know the initial equations which we combine in the lead up to the final expression (Ft)?

2022-11-11 21:48:25 UTC

Wk1 Non-dimensionalisation

2022-12-23 13:37:35 UTC

I noticed the expressions for A and B of the Shipley Ellis HFB correlation (and other expressions such as lambda_lim to calculate A and B etc.) are not included in the nomenclature & equation sheet on moodle. In an exam, would A and B be given to us as constants so we don't need to calculate them, or should we include the expressions for them in our own sheets of paper we can bring in to the exam?

Also, in some of the example questions from the Shipley paper pressures were given in psia - would we need to know the conversions to SI in an exam?

Can you give an example of when we would need to use the Graetz number in a question? It's in the equation list for the exam but I can't find any mention of it in the lecture notes

2023-01-08 12:09:38 UTC

Mock exam Q3

2023-01-08 12:13:07 UTC

Hi Sandhya, for Q3 we weren't give any data about the cell sizes and densities, nor the fluid properties (these were taken from the table in the lecture slides example). I assume in an exam we would be given this data and we don't need to remember common fluid values and the sizes/densities of different cell types?

FBB Correlations & equations

2023-01-08 14:01:00 UTC

Could you give us some example questions of when we would need to use any of the three coefficient of drag correlations, and the particle peclet number?

Responsible Innovation

2023-01-08 14:10:11 UTC

Will we be directly examined on any of the content from Kosta's lectures slides or is it more to get us thinking about bioreactor design in terms of ethics, sustainability, triple bottom line etc.

Exam 2018/19 Q1 (d) (ii)

2023-01-08 15:18:39 UTC

For this question do we need to show the full derivation from the mass balance to the compartmental analysis expression, or can we just state the assumptions that are used to get to that equation/why we can use it?

CD34+ Cells

2023-01-08 16:10:42 UTC

Hi Sandhya, I was just wondering if CD34+ cells are considered stem cells (i.e. a type of hemocytoblast) or if they are committed cells (i.e., proerythroblasts). Thanks!

2023-01-09 15:29:59 UTC

Hi Sandhya, why does the adsorption term reduce to kC? When can it not be reduced to kC and why? Therefore, what does this term describe?

2017/18 Past Paper Q1c (i) and (iii)

2023-01-09 15:41:19 UTC

Hi Sandhya, here are my questions from the revision session with the question above for context:

For (i) we’re asked to select an inlet and outlet oxygen tension for a BAL HFB design that will outcompete rivals and I’m not sure if we should base the range on that of a typical human liver sinusoid (60 to 35) or a greater range than the excorp one given in the question so 90 to 77? I agree I think it may be the latter because we need to output rivals, but would there be a benefit of having a Cn < 77? Would this mean better oxygen uptake along the length of the fibre?

For (iii) we’re asked to state the assumptions implicit to the method used in part (i), but I think it’s meant to say part (ii) and be referring to the HFB modelling assumptions as I'm not sure what assumptions we would use for the oxygen tension question? In this case can we use any of the HFB modelling assumptions or are there specific ones that are more relevant to the question?

mock exam Q3

2023-01-09 18:26:56 UTC

Hi Sandhya, please may you let me know the lecture in which the material required to answer Q3 of the mock exam is covered?

I am having a hard time understanding a few things with this question:
1.) What ReP,u(t) is and why it is important if it is < 0.2
2.) What n is in this case and how you calculated it.
3.) Why did you / why could you assume an aspect ratio (epsilon) of 0.4.

Additionally, are we expected to be able to estimate cell diameters and densities in the exam and to memorise cell diameters? No data was given for this question so I am unsure how you justified / decided on these values. Thank you!

HFB temp control

2023-01-11 11:38:41 UTC

Hi Sandhya, are hollow fibre bioreactors jacketed to maintain the temperature or is this just done by controlling the temperature of the inlet media? Thanks