 I am working with Agninoji, Anja Bojic and Rudi Podgornik, my collaborators, and at first let me tell you a brief introduction to viruses. Many of viruses could be approximated as a spherical-like shape for the outside of the virus. Some viruses are made of capsids, which are in fact made of proteins. The proteins are encoded in the viral genome, which could be RNA or DNA. But some viruses like the famous coronavirus are enveloped by a lipid membrane, and the genome is inside this lipid membrane. They also may have spike proteins, and the HIV virus has also the same kind of strategy to impact cells. But many of viruses are non-spherical, as well. For example, some of the first plant's virus, which was the first virus discovered, was tuberculosis virus, which is a rod-like virus. Or some DNA bacteriophages, which means the virus is infecting bacteria. They also have a non-spherical shape, and some of them have very long tails. And all viruses depend on living cells for their reproduction. Now I want to tell you something about importance of electrostatics to viruses. As Ali, I mean, Ali Naji said in his talk yesterday, viral shells are charged. They could have positive or negative charge for the outside or inside of their surface. For example, it is well-established that RNA viruses use electrostatic interactions, direct electrostatic interactions, with the interior part of the capsid of the virus, they're encapsulated inside. But for DNA viruses, for example, some of the bacteriophages, the strategy is different. And we have turret-like shapers made from DNA strands, which is the codes needed for virus to replicate. For this part, you can also remember DNA condensates that Ali talked about yesterday. And for such structures, multivalent ions are crucial, which we also want to focus on in this talk. Actually double-stranded DNA has two elementary charge for every base pair, which is about 3.4 nanometer of its length. And in the solution, we have both monovalent and multivalent ions. In addition, it has been shown that presence of multivalent ions for each virus, there are some multivalent ions which are crucial for its proper formation. And as Ali said yesterday, multivalent ions can cause attraction between same-sline charged surfaces. So to study the effect of multivalent ions on viral capsidizability or viral shell stability, we have used three different models. At first, we used an empty thin shell representing the empty capsid. And we used monocard simulations, we simulated explicitly multivalent ions. Such as spermine with full valency plus full valency. And monovalent salts was, in fact, simulated implicitly as a double screening environment. Then we tried to study the effect of, for example, DNA genome inside a bacteriophage with considering a nanodraplet having a constant volume charge density of rho. And then put this droplet inside the viral shell. So now, in the second model, the viral shell is not empty anymore. In our next model, we used, in fact, we started to simulate a done experiment on BMV viruses encapsulating gold nanoparticles having a coating layer, which you can see over here. This is the gold nanoparticle with radius r0. Then we have the coating layer of the gold nanoparticle with radius r1. This layer is charged, in fact, and could have positive or negative charge density on its surface. And it's impenetrable to multivalent ions. Then we have the viral shell of BMV virus. And the radius is r2. And in fact, it is always positively charged. It has a great positive charge. And for the Hamiltonian of the system, we used both a Debye-Huckel interaction and effective imed charts inside the gold nanoparticle between each pair of ions and between ions and charged surfaces, which are placed at r1 and r2, and between charged surfaces themselves. Our results show that, for example, for the charged anti-shell, which was our first model over here, we saw that we have multivalent counter ions of positive charge for plus 4-valence ions like spermine. Then we observed that for more negative charge density of the viral shell, we have more negative electrostatic pressure, which means more inward force on the shell and this can stabilize the viral shell because the force is not anymore positive because of the same sign charge of the different parts on the viral shell. So this was an effect only arising from 4-valence ions if we replaced the 4-valence ions with 3 or 2-valence ions, then we couldn't see this type of counter-intuitive result. Then when we had a nanodraplet encapsulated inside the virus, not only we saw that for a more negative sign, more negative charge of the volume charge density of the droplet, but in addition, for more negative surface charge density of the capsid, we could have more negative pressure or more stable capsid, which is very counter-intuitive, but also it can explain that why some DNA viruses have negatively charged shells instead of positively charged shells, which comes to mind at first. Then for the... Lelya, I had a question for you. So the negatively charged... So basically the thinking is that the negative charge is screened, that's why it's stabilized? No, by screening, we just will have less repulsive forces. Do you know? But because of multivalent counter-ions, not co-ions, but counter-ions, ions with the opposite sign of charge, we could have this effect because... Let me show you the next slide, please. For example, here we have counter-ions for the shell, and as you see, they condensate very precisely around the opposite charge shell. And then each of them could... This is my imagination. Each of these in fact multivalent counter-ions tries to neutralize some of the positive charge of the viral shell. And when they condensate over this shell, they can in fact induce positive attraction between these different parts. Or for example, between the two shells, which I am going to explain next. Did I answer your question? Yes, thanks. All right. So, Lady, you are keeping track of time, are you? I think you are at 11 minutes at least, because I'm a little confused. So you have maybe two or three minutes. Okay, go on. All right, sure. So in the presence of a golden particle encapsulated, we saw that not only a different sign between the first and second charge surfaces, the difference sign between them is not the only answer for stabilizing this nanoparticle inside the virus, which was the strategy used in the group of Professor Dragny. But also, if we have in here counter-ions are negatively charged, if we have multivalent counter-ions, we could see even attraction between positive R2 and positive R1. And the reason is, as I answered to the question of Alias, so this is a strategy that we could use to stabilize any kind of coating layer for the golden nanoparticle. Then we have used charge regulation kindly for some problem which has been done experimentally. We have been trying to find interaction between an FMT and a viral particle. And now we are working on coronavirus using charge regulation theory, which is more precise and accounts for different dissociation or association of hydrogen charge. And virus-like particles are in general important specifically in medical sciences. For example, virus-like particles do not have a wild-type genome inside them. And so they are used for vaccine production, targeted drug delivery, gene therapy and so on. Thank you all for your attention. Well, thank you very much, Lely, almost at the 14 minutes mark. So, Justin, maybe I make a comment too, because we had one question, to Alias' question, that this is the type of interaction I was talking about in my talk. These are correlation interactions. Basically, it's not screening, it's completely different from device screening. So because you have lots of neutralizing charges in the form of a plasma, a very dense plasma, and basically they manage to show the whole picture, but we can talk about it later. That can create a lot of negative self-energy for the whole complex, complex of nano-particle genome charge within the simple model we are using, actually. So, thank you very much, everybody. So we are 15...