 Dr. O'Hare, this is one of my favorite groups of chemical control agents. You have the peroxogens. If you've ever been in a lab with me, you know how I feel about using hydrogen peroxide as a wonderful disinfectant. So how they work is just remember that hopefully you've seen the earlier videos about oxygen requirements for growth, that all living things that are exposed to oxygen have to deal with it. We think of oxygen as a good thing, but oxygen creates all sorts of toxic forms and if you don't have the machinery to deal with toxic forms of oxygen is going to cause lots and lots of problems. Even if you do have the machinery to deal with it like we do, it still leads to problems over time. So you see here how these work. It says oxidation, which would be the peeling off of electrons, and destabilization of cellular macromolecules. Let's put that in English. They work by creating free radicals. So the most common free radicals are called reactive oxygen species. So the proxogens are going to generate a ton of reactive oxygen species, and if you're an anaerobic organism that can't deal with any of them, it's going to wipe you out. If you're an organism like us or many of your obligate aerobic bacteria, then they're going to have the enzymes to neutralize some of these reactive oxygen species, some of these free radicals, but you can overwhelm them. So the key with hydrogen peroxide is to use a high enough concentration. If you dilute the other proxogens too, we'll talk about hydrogen peroxide first, if you dilute hydrogen peroxide too much, then it may not kill all organisms. But I've worked in the lab for 12 years now. My mentor worked in the lab for 27 years, and we both agreed that hydrogen peroxide is a wonderful way to kill the microbes in a microbiology lab. So all right, so that's kind of the proxogens in general. Let's talk a little bit more about hydrogen peroxide. So by far, hydrogen peroxide known as H202, you can see on the image there, is by far the most widely used peroxogens. So it can be used as a disinfectant and an antiseptic. It can even be used as a gas in gases. So a lot of times they'll spray like steams or gases of hydrogen peroxide when they're creating aseptic packaging like for food and these kind of things. So I already told you how it works. It generates a whole bunch of free radicals that some organisms can't deal with any, some can deal with some. But if you overwhelm the system, it will kill pretty much anything. So here we see just in this image, the reason I shared a couple things. You see a bottle of hydrogen peroxide. Notice those bottles are always dark because light can inactivate hydrogen peroxide and on the right, you're looking at a contact lens cleaner. And that bubbling is actually the enzyme catalase that takes hydrogen peroxide and creates water and oxygen out of it. So when you put hydrogen peroxide on a wound and you see a bubbling, it's not so much evidence that it's working. If anything, it might be evidence that it's not, that it's being inactivated. So I'm definitely not big on hydrogen peroxide being used on deep wounds, you know, surface scrapes, those kind of things are probably okay. But this is why you do have to make sure you use the right concentration of hydrogen peroxide because you're dealing with an organism that has enzymes like catalase, they will be able to neutralize a certain amount of it. All right, so that's hydrogen peroxide. Next, we have paracetic acid on the list here. So paracetic acid, how I've seen this being used, it is effective against some of the organisms that maybe hydrogen peroxide can't deal with because they have the enzymes that can break it down. Paracetic acid, it can be used as a liquor, but also as plasma. I'll cover what plasma is later, but it's the, you can actually create disinfectants that are the fourth state of matter, that aren't solid, liquid or gases. The reason paracetic acid is so good is that it really, really effective at killing spores, which are always a big concern. I've seen it used mainly with fruit, like spraying it on fruit and those kind of things at this point. But I will think, I think you're going to see more paracetic acid, or I believe they call it PAA in the future. A couple more here. So benzoil peroxide and then carbamide peroxide. Benzoil peroxide maybe you've heard of as an acne medication. So it's used to kill propionobacterium acne, which is associated with acne. It doesn't cause it in all cases, but certainly is associated with it. And then carbamide peroxide, this is, you're going to see this one used in toothpates. So it helps to kill the pathogens that in the mouth, streptococcus mutans that can lead to cavities. And also it helps to disrupt the biofilms these organisms like to hide behind. And then of course, the carbamide peroxide can also play a role in keeping your teeth from getting discolored. So those would be some examples. The last example is ozone. So I'll do more videos on water treatment separately later. But ozone is O3, unlike atmospheric oxygen, which is O2. So ozone can be used to treat water. I think at this point in the United States, it's used in about 5% of municipalities. But if maybe chlorine's not doing the job or you want to make sure your water is safe, you can use ozone there as a water treatment. All right, so those are your peroxogens, hydrogen peroxide, parasitic acid, benzoil peroxide, carbamide peroxide, and ozone gas. Very, very effective at controlling microbial growth. Okay, have a wonderful day. Be blessed.