 Thank you so much for giving me this opportunity to talk about my research among all these great scientists. It's been a really great presentation. I have a short presentation on how we can use X-ray microtomography and SCM to study the material of free stride probiotics. So my name is Fry Bay and I'm a PhD student at Lund University. I'm working on enhancing the shelf life of probiotics. So my supervisors in this project are Anna Furibi from RISE and Emma Larsson from Lund University. So this project is divided into two parts. The first part is it's a classic investigation where we look at the structures of free stride material. We want to determine the parameters such as pore size, poor connectivity and tortuosity. So all these parameters affect the free stride process and give us the valuable information on how we should design a free stride process. Other information we can obtain from tomography is the wall sickness and where the bacterial cells are located in this material. So these are parameters that can play an important role when we look at the shelf life of these probiotics. So the second part of the project is much more challenging but more exciting I think and that is we want to investigate the dynamics of the free stride. So how are the structures formed? We study the movement during freezing and also the movement that happens during drying. But let us start by looking at the structures formed after free stride. So we can just by looking at these same pictures. So these are same pictures of free stride material of amorphous material. In this instance it's multi-deck screen. We can clearly see that there is a difference between the structures but it's not easy to draw any conclusions on pore size or wall sickness and this is of course the reason we need x-ray tomography. I will go into details on what kind of structures we see in these pictures later on. So the first part of our experiment where we look at the structures was performed at the division of solid mechanics at Lund University. So the equipment we used here is an x-ray lab tomograph from size and it's a state-of-the-art very good equipment. After scanning we obtain slices of free stride material that we can build up to obtain a 3D image of this structure. So after obtaining this 3D image of the free stride cake we need to analyze the structure so here we have three different free stride structures from three different free striding protocols. In short the first structure on the left is free stride at the low temperature and the middle one is done at a little bit higher temperature and the one to the right has undergone a kneeling process. I should also emphasize that it's important to do a proper preparatory work to remove noise and interference and to set the proper threshold to ensure that all the materials are included. So not until then can we start analyzing the structure. But let us start by looking at the pore size of these free stride material. So the pore size is analyzed using a method called water segmentation or water shedding. And we can see the different pores represented by the different colors here but it's still quite difficult to see any major differences between the structures. So what we can do is we plot the amount of pores with the equivalent diameter and we obtain a graph that looks something like this. So by looking at these graphs we can see that the difference between the first and second sample is not that significant while the third samples contains larger pores. It should be noticed that this is plotted to the amount. Maybe we should plot to a volume then we will see a clearer difference. So the larger pore size should lead to a smaller surface area and that leads to a smaller surface area means that it's a thicker material and this is something we can confirm by analyzing the local thickness. So looking at the local thickness here we can see that the thin parts here are colored purple and the thicker parts are colored red and yellow and as expected the difference between the first and second sample is not that noticeable while the third samples clearly have a thicker material so confirming our hypothesis. This is very valuable information when we want to investigate how how structures can influence the shelf life of probiotics. But all these samples has has been done to finish a finished product a free stride product and if we want to understand how these structures are created we need to study the movement during free stride and here comes the second exciting part of our study. So we have thought long and hard on how the materials move during free stride and have come up with a hypothesis that can potentially be confirmed using x-ray microtomography. So I have made this short illustration on how we think free stride works so we have a state diagrams of sugar water system a typical free stride program and an illusion on illustration on how we think the movements happens. I will not go into detail but to sum it up we think that there is a structure formed during freezing we call that the primary structure but to be able to drive the sample the primary structure needs to be connected and create the pass to the vacuum so this movement creates another structure called the secondary structure that consists of pores that is connected to each other and out to the vacuum. So if we can investigate the movement of ice crystals and the material we can confirm or invalidate this theory but there is this is a challenging task and we have few hurdles to overcome all right. So the first hurdle is to build a free stride that can work inside a beam line and moreover have a representative sample environment here you can see a prototype of a mini free stride that probably fits in the beam line. Other challenges is to get the contrast between sugar and ice and also to have enough fast enough imaging that we can record the movement so let's look at these challenges in detail. So we have worked a lot with free stride and we have quite a good idea on how a free stride amorphous material looks like when we free stride in a vial but when we tested our sample environment it turned out quite differently so up here you can see this this structure that we are used to and here here is the tomography picture of our sample environment free stride in our sample environment so this kind of structure is a typical phenomenon called directional supercooling and this kind of structure are more connected and can easily create the pass to the vacuum resulting that we they keep their primary structure and preventing the movement to form the secondary structure. So this is a phenomena unusual in the ordinary free stride even if we see it sometimes but this is something that we want to avoid so there's a challenge on how we should how we should design our sample environment and if we see a water segmentation of this sample we can see that it looks very very different from a sample from a vial. Yes the other challenges we have is to obtain a contrast between sugar and water in the absorption range so in this graph here we see the linear attenuation coefficient plotted against the energy so to obtain a good contrast between sugar and water we need to have a difference between between these and as you can see this only happens at the lower energy levels and this can of course cause trouble when we need for example high flux to achieve a short exposure time we might there's possibility that we can overcome this problem by using phase contrast imaging but at the end it's a trade-off in exposure time in order to maximize the contrast and at the same time minimizing the sample blurring but all in all we have a found and challenging experiments to look ahead of us and it's going to be very exciting to see what a synchrotron can provide for our experiments and that's all for me I would like to thank my supervisors Anna Furebi and Amalia Larsson for all the help and support I would also like to thank Pio Gaia for funding my PhD project and of course to Vinova that is funding this this project all right and any questions there was at least one in the chat here from Tommy Tommy asks does the interfacial zone during drying look different from the bulk in your system say that again in I can see the chat okay interfacial so what do you mean by interfacial zone Tommy can you elaborate yeah I just mean when you do your drying you create an interface as you you have your solution and there is an interface with air and then you freeze the whole thing and it starts to dry I'm just curious because when you do ordinary freeze drying the top often look a little bit different from the from the bulk so just yeah I see that is do you see something like that and and have you looked into that that you should be able to monitor in your images yes so we see we see quite the big difference between the absolute top layer of of the freeze dried cape but the bulk and the bottom keeps if it's a well-designed freeze drying program there's no difference within the bulk so there's no difference between upper layer and further down the sample but the top looks very different from from the rest of the cake and and we have actually quite challenging we don't really understand how the structures on the top are formed because it sometimes look like just the sheet and sometimes it's very porous sometimes it's elongated pores we don't know if these structures are are originated from the freezing or from the drying part yes so so because I guess when you're at least when you do ordinary freeze drying it often seems that the top layer is harder if you want to dissolve it again it is much more challenging so it would be interesting to look into yeah we are not in the second part of a project where we look at the movement we're not so when we talk about the top layer we talk about the top layer of the material so then there's a top layer of where the drying happens that's it's called the sublimation front and that's where the movements are interesting for us to look at because we think that's that part at the sublimation front we determine a lot of the parameters we look at that's where the movement happens you could say okay yes thank you thank you Tommy yeah can I ask so so what is the the time scale you're measuring on you you were doing time to resolve the yeah how long does it take to make one of your your scans that is something we have not gone into the freeze drying process per se we can design to be faster or slower so but but to record this movement in this small small scale it can be very challenging but we of course want to have we want to find a beam line that has the highest highest amount of flux at our energy level so basically we we we want to maximize the exposure minimize the exposure time as much as we can without without losing the contrast yeah so i am manual here maybe i can give some details so the the the scans that were showed here that you saw they they took rough roughly i would say we really pushed the resolution so with the lab scan it took around nine hours actually okay but i mean this is in a lab based environment if you go to synchrotron you have higher flux so you'll be able to image much faster let's say but um and exposure time i will need to double check but i think it was between five and 12 seconds or something okay no i mean so let me just comment that the the reason i'm asking is because together with a colleague martin karmapirsson at the nil's bow institute we we have some new analysis tool using computational topology and we're quite interested into to getting some time resolved tomography data from a food-based system so maybe i'll send you an email about okay sure that would be really appreciated thank you are there any other questions or one last question maybe then i assume there will be a neutron tomography beam line at the ess would that help you oh we talked about neutron tomography i think yeah we we landed on x-ray tomography uh the the exact reason should i i should maybe refer this question to a model again yeah i mean yeah so i mean we basically concluded that for for this application for this freestyle products we need basically sub micrometer resolution yeah so let's say 0.8 microns or so and i mean if we go to a neutron tomography current state of the art is more around a 10-ish microns currently but uh if we wait a couple of years also maybe we would be happy to explore some neutron tomography for this application so um yeah that's basically it yep thank you for your replies both of you and for your talk very nice