 Alright, good afternoon everybody and welcome to the Celebrating Faculty Career series. This series started in 2013 and it is really an outcome of two separate actions. One that came out of the last strategic plan and a second that actually came out of our initiative with the Faculty of 2020. Both those initiatives had a special emphasis on professional development of faculty through all stages of their career. This particular series celebrates in particular our full professors who have been in rank seven years or longer and what it really tries to do is have some of our star faculty members like Steve present in a forum like this in front of faculty, staff and students a talk that is not just about research, not just about engagement, not just about education but about all three and in part reflective upon their careers, their path to success and in part forward looking about what opportunities exist in the future. So thank you all for coming and it is really my distinct honor today to present Steve Boudin for this Celebrating Faculty Success talk. A few words about Steve. He got his undergraduate degree at MIT in 1988, master's in 1990 at the University of Texas in Austin and his PhD also in chemical engineering, all three degrees in chemical engineering at North Carolina State in 1995. And he has been the recipient of so many awards that I literally have to look up my notes to tell you what they are but it is a long list but it starts certainly with the NSF Early Career Award. He has been named Purdue University Faculty Scholar, Purdue University Provost Fellow, inaugural class and he has really been the recipient of numerous awards in teaching including the Purdue University Student Government Teaching Excellence Award, the inaugural recipient, 2015 Outstanding Mentor Award from the Purdue University for Purdue's College of Engineering, the 2017 Shrieve Prize for Outstanding Undergraduate Education in Purdue School of Chemical Engineering and the PhD Resistance, the 2017 Potter Award for Teaching Excellence from the Purdue College of Engineering which is the highest distinction for teaching in the college. Professor Boudin's career has really been marked by a dedication to student centric teaching, everything from peer learning to the use of technologies to mentoring students, all angles and it reflects in all the awards he has learned. His research has focused really on particulate adhesion in many contexts. Started from the microelectronics industry at first, moved on to pharmaceuticals and then it's moved now to much more energetic space. So without further ado, let's welcome Steve. Thank you. I appreciate the very nice introduction. So I've been here since 2003. This is the first time I've been at the front of this room in front of an audience of my peers and I'm delighted to be here and I'm grateful to you for taking the time. I'm going to turn the lights down a little bit because the graphics will show up a little better and let's just get started. So I wanted to choose an exciting title so I choose Let's Hope Something Sticks. So it's about adhesion and then also we're trying to teach people and we're hoping that they remember. And so I'm going to go over both of those kinds of things today, a little bit of a review of the research and a little bit on what it's like to be in the classroom the way that I'm in the classroom. So just one thing. So you've all seen City Slickers and there's Mitch there on the right and Jack Palin's curly the trail boss on the left and he asks Mitch, do you want to know the secret of life? And of course Mitch says yes. And then Curly says it's this. To which Mitch responds, fingers. To which Curly responds, it's one thing. Remember that out and everything else is just math. It's a different four letter word that Curly used but the idea is one principle, primary focus. So I thought I would start off with what mine was from a professional perspective and that was to be the kind of professor that we all wish we had when we were undergraduates who we very often didn't have. But the person that we wished would have reached out to us, would have inspired us, mentored us, sort of engaged us individually to push us forward. So that's what I've tried to do. I'll talk a little bit about my mentors. Prior to getting here, Ruben and Christine were my PhD mentors. Rich Felder who is the leading voice on engineering education was my teaching mentor. Greg Ropp who's got two degrees from Purdue, a bachelor's and master's in chemical engineering was my faculty mentor. The first three were at North Carolina State. They taught me how to be a researcher, how to be a scholar. Rich taught me how to teach. I spent a year watching him do it. It was an honor. And then Greg at Arizona State taught me how to be a professor. Which is not a self-evident thing. But Greg was an outstanding mentor and if you spend five minutes with Nick Delgas you would know that Greg was a Delgas student because it almost sounds like the same person talking with the same philosophy. I offer that as high praise. Since I've been here I've been very grateful to have a number of excellent mentors. And you can see I won't go through all of the names up there but Chris mentored me when I was in the provost's office the first time through. And then Leah and Rex through our engagement and all kinds of different projects trying to move things forward. Bob Davis retired after a very, very successful career in industry and when he was here in engineering education I had lunch with him every week and asked him to teach me to be a leader. We just sat and just threw questions at him. It was a wonderful year that we were able to do that together. Joe Peckney taught me how to do 17 things at once and I enjoyed that very much. Since Sang has been the head I've been very grateful for the guidance that he's given me to help me move the center forward that I'll talk to you about a little bit later on. And how to think strategically at the university level. And I worked very closely with Frank Dooley for 18 months when I was on my second time through the provost's office. And I'm grateful for them. And some of the specific things they helped me understand was how to accept criticism which is not always constructive in the university setting as we all know. And when you're the person at the front of the meeting with the suit on, you don't have the luxury of taking it personally when the criticism is not constructive and how do you do that gracefully? And it was very valuable to learn that. How to be transparent and how to be strategic. It's not obvious how to do either of those things but there's a way to do it and I was grateful for their guidance. And then finally, and this is what Bob taught me, was how to be effective which very often means you're not going to be right. So he would talk to me frequently about do you want to be effective or do you want to be right? The correct answer to that is effective. So I was grateful for their guidance. All right, these are the folks with whom I've had the pleasure of collaborating while I've been here. Lynn Taylor in IPPH, she and I work on a project on several projects focused on using polymers to break up crystals of pharmaceutical active ingredients to improve their bioavailability. We'll talk a little bit about that later on. It's a pleasure to work with Brian on some projects where we use engineered macromolecules, that's the right lingo. That's the right lingo. And our focus has been on detecting explosive residues in airport settings. It's been a pleasure to work with Dave and I'm sorry that the low res picture doesn't do him justice. He's a much more handsome man than that appears right there. But Dave and I have been doing some really interesting and exciting work looking at how water interacts with surfaces and also how to measure adhesion without making contact with anything. And working together and I'm not going to talk about that particular project today because it's so highly theoretical I thought for a general audience it might miss the mark. But to be able to make measurements of adhesion without letting things touch each other is a problem that's been pursued for almost 50 years. And with Dave's guidance and assistance we've been able to solve it and I'm very excited about that. But it's a festival of math and so I'm going to spare you that. And then it's been a pleasure to work with Steve's son on a new project associated with hotspots and that has to do with explosives and the moment you hear about hotspots and explosives you should get excited. And I will show you a little bit about that later on. Okay, so particle adhesion is what I've studied. And I should mention Dan Hurleman. He and I were walking across the Arizona State campus one day. And Dan said you know people are gluing particles on atomic force microscope cantilevers and measuring adhesion. And I thought that sounds like the most difficult thing anyone could ever try to do. I think I'll make that my research agenda because then I won't have any competitors. And that's largely been the way it's worked out. So we started focusing on particle adhesion and early on it was all about ultra clean surfaces for microelectronics. Arizona State is surrounded by Intel. You can't go more than a mile in any direction without running it into an Intel fab. I got here to Purdue and Rex got me excited to work with the pharma industry on powder processing because all of those issues of particles adhering and powders adhering are all based upon the same fundamentals as particles adhering to microelectronics surfaces. And then lately I didn't step backwards fast enough and ended up out in front of an effort associated with energetic materials because it turns out that making explosives, compounded explosives, is exactly the same fundamental process as making pharmaceuticals. All the same fundamentals apply. All the same theory applies. And so it was a natural slide to go over into the energetic materials explosives area. Let's talk about roughness effects on particle adhesion. That's where we'll start from a research perspective. So I told you we glue particles onto AFM candle levers. If we can get five or six of them glued on in an afternoon then we had a really good afternoon. My students are patient. Sometimes we use regular old AFM candle levers that are made rather precisely in terms of the head of the candle lever. And then we measure the force when the candle lever comes into contact with the surface and is pulled out of contact with that surface. And what we get is if we contact the candle lever against the surface a thousand times, we'll get a distribution of adhesion forces like this one. Sometimes the roughness on the candle lever or the roughness on the particle meshes perfectly with what's on the surface and so you get a rather large adhesion force. Other times the overlap is really poor and it's like table legs holding the two bulk surfaces apart and you get really weak adhesion and then sometimes you get something intermediate. You always get this and as I'll show you in a few moments you only need a few nanometers of roughness on either surface to cause a dramatic change in the adhesion force between two surfaces. And that ends up being a source of great interest to me and to a few other folks. In order to do this work the first thing we have to do is characterize what these particles are that we put on a surface they're not always perfect spheres. So this is an aluminum particle and the software we use is called photomodeler and the way that works it's the same thing that archaeologists use when they find bone fragments in the desert and they put node points on and they grid this stuff out and then they put the nodes back together and they make a 3D wire frame mesh of the object. And you need to take pictures with an SEM from a bunch of different angles and then after you merge all of those different nodes we come back with a second cantilever and run that over the surface to get the nanoscale topography on the surface. So the wire mesh gets us the macroscopic shape and then the cantilever gets us the nano level topography. We use a Fourier transform technique that lets us describe the roughness on the surface. And when we put a random phase shift in that Fourier transform before we transform back into real space that lets us move all the peaks around on the surface without changing the statistics of the roughness. So it allows us to simulate touching a surface in many different locations just computationally rather quickly. So that's a helpful thing to be able to do. And so what we're going to do is we measure geometry. We measure roughness. We build mathematically a particle. We bring it down to within four angstroms of separation from a surface. The community uses either they call contact three angstroms or four angstroms from separation from contact. Then we're going to discretize both the particle and the surface into nanoscale cylinders. And then we're going to sum the Van der Waals interaction between all of those cylinders. And that's kind of a brute force method and collaborating with Dave, who's much more precise, much more of a gourmet. I would call myself more of a gourmand. We've been able to improve the precision of the modeling there. That sort of brute force approach, though, allows us to get really nice data on the statistics of particles interacting with surfaces. And that's what we need because we're going to compare measured adhesion force distributions, like this green one right here for this silicon nitride particle interacting with tantalomoxy nitride, with our predicted distribution of adhesion forces, which is here in the blue. And based on that Fourier transform method that we use, we always predict a little broader distribution of adhesion forces than what we measure because you get some non-physical, when you randomly move the peaks around, you end up with some non-physical contacts on the surface. But what it does very well this approach is it allows us to capture the overall shape of the distribution pretty well and capture the mean behavior very well. And this allows us to say quite a bit about how particles and surfaces will adhere. So I'll show you some results here. This is from micron scale particles on surfaces. Here's a nice perfect round one. And you see this is the measured distribution and they're predicted. Over here, this is the irregular geometry that I just showed you. But this was when I really knew that we had it right. And all those of you who are parents recognize yurtle the turtle over here. So you see he's got little legs, and there's his head, and he's got a back. And so what you see is the nanoscale topography down here is what's going to dictate the adhesion between this particle and his surface. And what we found when we measured the behavior of yurtle up against, so yurtle is aluminum oxide, and we measured his behavior up against a silicon dioxide surface, what we found is this bimodal distribution of adhesion forces. We were doing these measurements underwater at controlled pH. And these bimodal distributions resulted from some cases where the topography on yurtle's feet matched perfectly with indentations on the substrate. And so then we got high-mode adhesion, which is this out here. And in other cases, the topography was always sitting on top of plateau where we got the low-mode adhesion. These distributions that you see right here have no adjustable parameters inside. It's strictly a function of the randomness of the geometry and the intersection of the two surfaces coming together over and over and over again. What's particularly interesting here is not only can we match the shape quite nicely, but if you really have great eyesight, you can see that at pH 9, the average force is about 13 or 14 nanonutans. pH 10, it's about 12 nanonutans. pH 11, it drops to about 10 nanonutans. That happens because there's a little bit of electrostatic repulsion between the particle and the surface, and that changes as the pH changes. And for a particle like this that has such an interesting geometry, there are some regions where van der Waals forces, which are what I model, are dominant, like right here. But then others where the separation is larger, where electrostatic forces will be dominant forces. So you start to see them creep in. And it's very rare for electrostatic forces to have an influence on two surfaces that are in contact. But if you get the right geometry, you can get that, and we can see that in the measurements. So we wanted to explore roughness again, and I'm sorry I'm going to show you very, very few equations. And this is one of them. It's just simply a sine wave. So we're going to do sines in both x and y direction. We're going to describe the amplitude and the wavelength of the sines. And we're going to make spherical particles that look like that one. And what we're going to do is we're going to start off with a particle down here that is only 50 nanometers sphere. It's going to have 5 nanometer roughness height. And the wavelength is going to be 20 nanometers of the rough bumps. And then you see we go from a 50 nanometer diameter, 100 nanometer diameter, 500 nanometer, one micron, and five microns. The roughness is the same on all of those. For the small ones, you see the roughness is completely dominant. For the large ones, you see you can't even identify the roughness on the surface. But what's really interesting is the effect of that roughness. We're talking about five nanometers of roughness on the surface. And if you look at the smooth particle, a perfectly smooth sphere of the same diameter, that's this path right here. And if you look at the predictions for the rough particles that I'm showing you right now, we're order magnitude and a half lower from micron scale particle just by the addition of five nanometers of roughness on the surface. That's profound, because you can never get away from that level of roughness. And so that means in order to describe the way that particles and powders behave, we have to understand these very fine surface phenomena and their influence. And as you can imagine, with a lot of particles, this is going to become a problem. OK. So let's talk about inhomogeneous surfaces for a few minutes. And so here's my particle. It's in touch with the surface. And now this surface is going to have all kinds of different layers that have different composition. And what matters here is that the composition varies over the same length scale that the Van der Waals force matters. So the composition is varying over 10 to 20 nanometers length scale. There's no theory to describe that. In order to describe it, you have to be able to if we want to use this method that we've been using. You have to be able to describe how one cylinder interacts with some cylinder that's off axis and is finite in dimension. And you have to be able to describe how two finite cylinders that are coaxial behave. There is not a closed form way to do that. So we did some geometrical tricks to try to develop a closed form way to do that. It's possible to do this calculation if you just go one atom in one surface and calculate its interaction force with one atom in another surface and some between all of the atoms. And you can do that. And that's the most rigorous way to do it. It just takes forever. We were looking for something faster. And so we wanted an analytical or approximate approach. And so it turns out that if you take a finite cylinder and calculate its interaction force with an infinite cylinder, you can get a number. And then if you, whoops, it's back up. It's back up again. If you take that same finite cylinder and then you go with a cylinder that, excuse me, a toroid that has a finite inner radius but an infinite outer radius, and you subtract those two, what you're left with is the coaxial cylinders. If you do the same thing now, if you take a cylinder against a small one against a large one, a small one against a slightly smaller one, and you subtract those, you get a cylinder against the toroid. Then if you break that toroid up into a whole bunch of other cylinders, now you have off-axis. So these two little geometrical tricks allowed us to do some calculations. And what that allowed us to do, this is a normalized adhesion force as a function of the off-axis distance here, r. And the red is the model that we developed, the geometrical model. And the blue is the exact model integrating molecule by molecule across the two surfaces. And you see the agreement is really outstanding. And then if you want to look at the coaxial cylinders here, this is the same sort of prediction. This is the normalized force as a function of, in this case, r is the radius of the cylinder, and the separation distance was held constant at 5 nanometers. And you see the exact model here in blue, excuse me, the exact model in red, and our prediction in blue line up really extremely well. And so these sort of simple geometrical models that run for 20 minutes on a desktop computer lets you get quite a bit of mileage. You're probably wondering why I'm presenting this to you. I'm presenting this because we can do something interesting with it. And the interesting thing is over here on this left-hand side, this is the lateral adhesion force between a particle. In this case, we have a 25 nanometer particle approaching a surface that has copper, silicon dioxide, and copper. And if you start in the middle, you take that 25 nanometer particle and you drop it right in the middle right here, and you let it be one nanometer away from the surface, so it's basically in contact. It's a dust particle. It floated down. It sat there. It really doesn't experience any net adhesion force pulling it one way or the other. Now, these forces over here are negative because they're pulling the particle in the minus x direction. And these are positive. They're pulling it in the plus x direction. But as you move that particle off the very center and it starts to see this interface, the force gets larger and larger and larger, pulling it over until it reaches a maximum right here when the particle is centered so that its edge is right up against the interface, so that its center is right over the interface. And as you move further and further out over the copper, the force pulling it that way drops. What this says is that the particles are always going to get dragged to the interface. The particles are going to tend, if they can see the interface from an electronic perspective, they want to go there. You won't find them sitting away from the interface. They all aggregate in the crack in the one place that's the hardest to clean. And so we can predict that. And that was very useful for the people in the micro electronics industry to understand why is the contamination always showing up at the interface between our copper lines and our silicon dioxide fields of insulator. We can also do the same calculation and calculate the vertical adhesion force. And you can see it's substantially larger over the copper than it is over the oxide. And it transitions smoothly the same way that we see the transition over here in terms of the lateral force. So that was a nice contribution to be able to make it let us guide our industry partners on how to clean the wafers. So for single particles, we can describe effects of variations in topography and composition on the adhesion. And that's interesting. But it's one particle at a time. And only patient people can do it who have AFM that cost $750,000. And I didn't buy that Purdue had that for me, and I'm grateful. So later on, we'll talk about doing something a little more interesting where we work on the whole powder. But let's change gears right now and talk about teaching a little bit. So let's talk about making it stick in the classroom. So teaching effectively or making it stick. So great Rich Felder told me once that if you really think about it, students are remarkably like people. And I thought that was a wise thing to say. And I looked at him and I said, yeah, Rich, but faculty are the people that no one invited to the dance in high school. No offense to any of you who were invited to the dance in high school. But my guess is you weren't expecting to be invited. So what I'm trying to point out here is that there's a fundamental disconnect between us and the students we teach. We're generally not wired the same way. There's a few students who are wired as we are. But when you think about all of the students who could be sitting in this lecture hall while I'm teaching on any given morning, we're not all wired the same way. That's the point I want to make. So let's meet your professor. We're in academia because it's self-selected people who could sit in lectures like this and take notes for 50 minutes with perfect concentration or reasonably good concentration and learn. It's self-selected those of us who could read the book and figure it out for ourselves. It's self-selected people who could learn sequentially because that's the way the lectures are presented. We derive and then we derive the next and the next. And the people who were good at that, we moved forward. We have to be really good at time-bound exams or else we didn't make it out of the gate. We're pretty good at one task at a time. We're not so good unless we're Joe Peckney more than that. And it's unlikely that we had any significant learning challenges when we were coming up through the K-12, simply because K-12 would not have accommodated us if we had significant disabilities in terms of our learning when we were kids. That's changed now. But when we were kids, that's the way it was. Now we also have this generational relationship with information. So if I might address my seasoned colleagues, you encountered PCs on the internet when you were adults. You already had your ways of thinking and working. It was already ingrained when that stuff showed up. Folks like myself, I remember going to high school. It was such a big day when the Tandy Radio Shack, I can't remember what it was, showed up. And we had six of them on a bench because we had a computer room. And it was awesome. And the young faculty here have always had PCs on the internet available. So our relationship to information is very different. That means the relationship to the way we learn is very different, even amongst generations in the faculty. So now let's think about our students. Our students have had smart devices since they were born. My youngest son, who has severe autism, we handed him an iPhone one day. And 30 seconds later, he was surfing the internet. So he was six. So these students have a very different relationship with information and with learning. They find examples or solutions on the internet. They think that's learning. And for them, it is learning. That's where they go get information. That's how they solve problems. They go look it up. And they're very good and very fast at that. They watch examples. We put them in robotics. We put them in build circuit boards. We send them out to all of these different kinds of things. They expect that they will always have computational tools available to them, even if it's a phone. Because those computational tools are ubiquitous. And they've never had it any other way. They've learned that they can rage quit with no consequence. My son taught me rage quit. You play the video game, it's not working out. You just quit. Then you start and you play over again. There's no consequence. So you try, it doesn't work, quit. Try, it doesn't work, quit. Just start, just start. There's no consequence to that. And you just keep trying. And you try to beat the big boss battle. You try 100 times. You try 200 times. You finally beat the big boss. You move on to the next level. That's the way that this generation of students was conditioned. Those were the games that they played. They don't have a lot of patience for things that don't capture their interest. Because so much captures their interest on all of these devices continuously. And it's always there and available for them. And they multitask with ease. I have conversations with my son. And he never looks up from playing the game on his phone. And I ask him, did you hear anything I said? And he repeats back everything I said. So they multitask much differently than we ever did. And K-12 has improved in students with learning disabilities get here now. And they did not in great numbers in the past. And that does make a difference to our teaching. And it will make a bigger difference going forward in our teaching. So if we want to make things stick to help our students learn, perhaps we should consider teaching students instead of the way we were taught, rather the way that they learn is the idea. And so learner-focused instruction is what I try to do. And it seems to be effective. And I advocate that for my colleagues. So we try to have active sessions throughout the lectures. I've co-taught with several people here in the audience. And we all pick it up, and we all get into it. And the energy level in the room comes way up. The trick is to be respectful of students with disabilities. There are students who have anxiety concerns. If you ask them to talk to someone next to them, they are going to fall apart. And so 10 years ago, it was active learning, put them all in groups. And those students who had those kinds of challenges were, we just made their lives absolutely miserable. So now we can say, work with people around you if you're comfortable with that. If not, you can be on your own. And there'll be four or five students who will never want to pair up with anybody else. And that's not because there's anything bad about it. It's because often they physically can't do it. You just made the problem much, much harder for them in terms of being able to learn and being able to work problems. I like to try to have bite-sized sessions of instruction that sort of match the time between commercials on TV shows, although now they're streaming on Hulu or whatever else they're streaming on. They need context, because they're used to being able to find that all the time on the internet with everything that they investigate. And then this one's important. We present theory to our students that took 75 years to develop. And we derive it magnificently in five minutes, as though it were obvious, and then just want to move along. And they're sitting there wondering, how on earth would I have been able to understand that, or should I be able to have gotten it that fast? And if we can give them context and manage expectations, no, you were not expected to think of this on your own that helps them. I also like to emphasize helping them succeed in life. They are sometimes interested in their grades, but when they appreciate that you're trying to help them succeed bigger picture, they work harder. They forgive errors at the front of the room, and they'll do better. OK, so I've talked about minimizing barriers between faculty and students. Now, I started this thing called We Are Purdue the second year after I got here, which was long before Purdue started doing something called We Are Purdue. I did not enforce my copyright. So students are going to work in a global community. Students 25 or 30 years ago maybe thought they were going to come to Purdue and get a job in Indiana and never leave. But that's not the case now. And our student body is very diverse. But if you don't do anything, you'll see the students all come to class and they self-segregate into groups. And you'll be able to say, OK, these are all the students who are from Southeast Asia, and over here is where all the students, they all sort of into the most comfortable group for them. That doesn't necessarily prepare them to succeed in the broader world. So we put students into groups, and we give them an important question to answer with each homework assignment. And I'll give you an example of one of those. But the point is that we make them get to know each other with that question. So for example, I might ask you to pair up. I won't, but I might. And say, please discuss with the person sitting next to you the most fantastic meal you ever ate. Where was it? What made it special? Who else was there? Why do you remember it so vividly? So you can't have that conversation without sort of exposing something of yourself to whoever that person is sitting next to you. And that causes you to sit with that person who's from the other part of the world and get to know that person as a person, and understand that person a little bit better as a person, which helps you to be more capable when you're out in the world and you get assigned to work in that foreign country. So we have them work on problems like this with every homework that they hand in so that they can learn how to be part of a global community, learn how to appreciate each other and view each other as humans rather than just that person who I have to encounter. So they appreciate and respect differences, and they understand why people are different. And then the last part I'll talk about here is mental illness is one that is important to me. And every semester I encounter more and more students who are there with me on this. But they're getting to Purdue now, students who have challenges with their learning, with things like depression or whatnot. But they are often afraid to seek help. I've had students in my office saying, once a week I can buy Ritalin from the kid in my dorm who sells it to make money to get through Purdue. So that's not the way you want to be getting through Purdue. So I talk with them about my depression and my ADD, and I say, am I not successful? Should I be ashamed? And they have not yet said I should be ashamed, although I'm afraid it's one day they might. But the point is to get them to realize that, OK, people have this. I look at them and say, I take three pills more every morning than you take. Big deal. Who cares? And what ends up happening is that the students get the courage to go get assistance. And every semester, two or three students from my class will come and see me and say, I went over to CAHPS. Now I'm seeing a counselor. Now I'm getting medicine. Things are going so much better. So you made a difference, even though you didn't teach them anything that was in the book. And that's going to help them to be more successful. And that's what it's all about at the end of the day. And I love getting this, but I get this a couple of times. A semester, I'll get this kind of thing in my teaching evaluation, just because I cared about them and tried to push them forward as professionals, rather than simply as people who are going to get a grade in my class. So the point is if we can recognize how students are unique, we can more effectively help them learn and be successful. So I advocate for that. All right, let's get back to research. Let's talk about polymers and hearing the crystals. So this is a representation of the solubility of drugs that are in our drug pipeline. So very soluble out here is great. Bioavailability is very high. You take the medicine, it gets into your bloodstream. It's wonderful. That's what's supposed to happen. Practically, insoluble over here is horrible. It's like you swallow a rock and out it comes. No therapeutic value at all. And that's where most of the medicines in our pipeline and increasingly the new ones we develop are all out there. So we have to find a way to break up that crystallinity so that there's better bioavailability for these drugs that we're developing. And the trick is to have them be amorphous. They're substantially more soluble and the bioavailability is much better if we can get them to be amorphous. So how do we get them to be amorphous? Because when we have them in solution, the way we purify them, they come out and they want to become crystalline. So we did some experiments here where they're rotating disc apparatus. The way this works is this rotates here in a solution. The solution gets pulled up, spins around, and gets slung out the sides. And we put a crystal of pharmaceutical ingredient on the surface there. And we're going to look at how that crystal grows or doesn't grow. Now, it turns out that there's some very specific relationships between the rate at which material moves to the surface of that crystal or not as a function of the way that you rotate that disc. And so the rotational speed of the one-half power is the key is the magic feature of this apparatus. And so this over here is the rate of growth of the crystal inside this environment. Don't worry about the equation. Don't worry about that one either. Let's just look over here. This is what matters. So in this region right here, where as you spin the disc faster, the rate goes up, this is a mass transfer controlled region. This means that getting material to the surface of the crystal is what's controlling the growth. Then out here in this flat region, this means it's controlled by integration. It means it's a molecule is stuck on the surface and it's running around looking for a spot where it can sit down as part of the crystal. And no matter how fast you rotate the disc, you don't increase that rate anymore. This is where we want to look at what's going on because this allows us to understand the kinetics, the process of growing a crystal. So we did that with phylo-tapine, which is a anti-hypertension drug. And so this is the concentration of phylo-tapine in solution as a function of time with our rotating disc apparatus. And it's dropping here when we have pure phylo-tapine because the phylo-tapine is leaving solution and it's growing on the crystal. So the concentration of solution is going down. When we do the same experiment, but we use, OK, I get this right, HPM, CAS, hyperomellose, cellulose acetate succinate. Yes. When we use that polymer in the solution, we see that we dramatically slow the rate at which the pharmaceutical ingredient crystallizes out. So that way the solution concentration stays high. So we know that the polymer does something to prevent the growth of the crystal. And now we want to understand what it does. So here's our experiment that I showed you a moment ago. This is with phylo-tapine all by itself as we increase the rotational speed. We see the rate goes up, up, up. This is mass transfer limited. And now this is kinetically limited. This is the integration on the surface. And then down here when we put the HPM, CAS, the integration rate is lower by about a factor of 3. So it's slowing down what's happening on the surface. We can see that. Now, it turns out that depending on the pH, we get a big difference. This is the rate without any polymer divided by the rate with polymer. When that's above 1, it means the polymer is effective. It's stopping the growth. So at low pH, it's reasonably effective. It's stopping the growth. And at high pH, it's much better at stopping the growth. So the question is, why does that happen? And I'll point you over here. This is the phylo-tapine molecule. And this is the HPM, CAS molecule. And it's got all of these carboxylic acid species in it. At the higher pH, those tend to deprotonate. And so now you have all these charged species. And instead of all hanging out together, they flop out in space like starfish. And so what we think happens is when those sit down on a surface and they flop out, like they occupy a whole bunch of space on the surface and more effectively block that surface from growth. And so let's take a look at that. This is the AFM work that we did in my lab. This is no HPM, CAS present. This is just growing crystal. You see we got a nice crystal face here. It's nice and smooth and flat. We're growing crystals of the phylo-tapine. Now at pH 3 with the HPM, CAS in there, you see all of this little speckly stuff. This is the polymer sitting down on that crystal in little aggregates. It's like we sprinkled salt on the surface. So it's all little balls of polymer. Then we go to the higher pH. Now it's all this smeary stuff. It looks like, actually, if we really look in a fine way on, it looks like fried eggs on the surface. And I'll show you what that looks like. Here is the cross-section at pH 3 of one of those bumps that I just showed you here, any one of these bumps. Characteristic size is it's about 30 nanometers in width, any one of those blobs on the surface. But if you look at pH almost 7, these are much, much, much larger and much less regular. That's because at the higher pH, those polymers are spread out. They're more like starfish with arms that are spread out all over the surface, blocking many sites. From that, we were able to learn that at the low pH, the polymer goes down in this coiled configuration. At the higher pH, it goes down in an extended conformation. And we actually were able to calculate, Lynn and I, that there's about 50 molecules in every one of those globs that goes down onto the surface. The same amount of polymer actually sits down on the surface. It just sits down in a different conformation, which influences the crystal growth differently. So we understand how polymers adsorb onto the crystals and interfere with the growth. And now we're working, Lynn and I, to develop ways to harness that, to change the bioavailability of crystals in the human body. All right, so now let's talk about going from single particles to powders. So powders are populations of particles, and their behavior is driven by nanoscale topography and microscale shape. If you're in the industry and you're trying to make pharmaceuticals, you've got great big huge vats of particles. And you've got to figure out how they're all going to behave in order to optimize any kind of process, which is sort of like using the characteristics of individual snowflakes to describe how snow accumulates in a blizzard. It's actually not very far from that at all. So why do we care about this? Well, maybe we just came up with a new drug, and our patent is ticking, and we need to get it formulated and get it out into market as fast as possible. We don't have the luxury of making large quantities of this drug so that we can do large-scale testing. We only have microgram or milligram quantities of this material to develop all of the scale up. And we need to do it quickly. So we need to be able to use small quantities of powder to characterize how a large powder will behave. Or perhaps we have a new explosive that we're going to compound, and we don't want a lot of it around. Davin, OK? And we might not even make large quantities of it, and we certainly don't want to be beating it up because that might not be pleasant, OK? So we have to understand how to use small quantities of material to understand how a large powder will behave. We use the centrifuge to do this. We put particles on the centerfuge, on plates that go in the centerfuge, and we spin them. And then we look and see how many particles are on there initially, and then after we spin it at a certain speed, how many particles are left. You see the one in the triangle is gone. And then again, we spin it a little more, and now the one in the circle is gone. And we look how many particles come off as a function of the rotational speed. And we get a map of the adhesion force of the entire, of the whole distribution of particles in the powder. And so it sort of works like that. So here's the plate, and it's parallel to the axis of rotation. And it looks like this. There's a whole bunch of silica particles on a stainless steel plate. And then we're going to put those plates on the centerfuge and spin them, and then afterwards we've got a whole lot less particles on there, OK? So now we're going to quantify that and try to learn how the powder behaves. So this is that experiment I just showed you. This is the way that the particles come off. This is a percent remaining as a function of the rotational speed that we observed for those silica particles on a plate. What we want to do is we want to use the simplest model on Earth. Sorry, this is the second equation, but there's no more than this, OK? The simplest model on Earth to describe the behavior of that powder. And this is for a perfect sphere on a perfect flat thing. And this is our force constant. And if we use this model, this is what we would predict should happen, for perfect spheres on perfect flat things instead of the reality. And what we want to do is we want to get those two to overlap, which means that we're going to take this distribution right here. And when we've got 98% of the particles still on, then that means 2% of this distribution is going to have to come off at this first rotational speed that we care about. And then over here, now we're down to 94% adhering. And so a little bit more of the distribution is going to come off. And then more, more, more, all the way through. And so we're adjusting this force constant all the way throughout the behavior that we see. And each individual force constant applies to a different piece of the size distribution of the particles in the powder. When we do this, we have the ability, when we do this, we end up predicting material coming off the surface quite different than what the perfect powder would have. But we get perfect agreement between the model for the simplest powder on Earth and the behavior of a very complicated real powder. And this information can get fed into all of the folks who run around doing DEM modeling, which is the way that people model large populations of powders. They desperately need some relationship for how the two particles stick together when they bump into each other in a great big vat when someone's turning the vat over and over and over. This gives them the simplest possible model to do that, which is something that's been sought for decades. So we're very happy with this. And we've developed this new tool that can characterize the adhesion behavior of powders, large, large, large quantities of powder based on very, very small samples, very simply and inexpensively. I'm kind of proud of the way that that worked out. All right, last little bit. And then I think I'm right on time, Marcia, is the Purdue Energetics Research Center. So there's our team up there. Davin is one of our new additions to the team who's in the back in materials engineering. And Chris is our other new addition to the team. They were both people we hired when we formed the team. This started as our preeminent team in energetic materials. And it grew into the Purdue Energetics Research Center, which I'll show you our logo in just a moment. And we focus on all of these different pieces of energetic materials. So there's some work. This is, it turns out, ordnance that was dropped in Iraq. And quite a bit of the IEDs that are used against our soldiers in Iraq actually was ordnance that we dropped that didn't explode. And so people go out into the desert or wherever it happens to be. They pick it up. They bring it back. They rework it. And then they drop it on the ground. And when you're driving along in your vehicle, the ground is littered with these. And which one is going to go off is the concern. And so people on our team are worried about how do we detect this and how do we defeat it without having to send somebody to walk over and pick it up and diffuse it. If you've seen the Hurt Locker, it's absolutely terrifying to imagine the person who has to go out and deal with every single one of those. So we want a way to do that remotely. And our team, whoops, our team works on that. Members of our team work with very, very thin layers of material on high-rate mechanics for a particular application in improving body armor so that when a munition strikes, the energy is dispersed and doesn't pass through to the soldier. Chris on our team and Terry Meyer work on doing laser diagnostics of what's going on inside fireballs. So by sending a laser through the fireball, we can look at what the chemical composition of that fireball is, the rate at which energy is being liberated, the different chemical reactions that are occurring, so that we can optimize the delivery of energy onto the person on whom the munition landed. Because that's what we need to do if we want to control a battlefield, because we have to have that energy be directed in a certain direction in a certain manner. Now, the F-35 is here because the F-35 flies at just about the limit of human endurance. If we do any better than the F-35, we're not going to be able to put a pilot in there. The G-forces, the vibration, the heat, primarily the G-forces and the vibration. The munitions that we strap on to the F-35 were World War II era. They're not that much more robust than humans. And so if we want to be able to fly a plane like that at its capability, an aircraft at its capability, we need improved munitions that will be able to withstand the G-forces and the vibration and the heat that's present when this plane is flying at its top performance. We've got folks on our team who look at sustainability, look at reclaiming groundwater, look at remediation of ranges where energetics were used, and then finally people looking at the entire life cycle. If you look at our federal budget, the amount of money that goes to the DoD and the amount of munitions that end up never being used, but they have to come back to a DoD site to be demilitarized, it's enormous. And can we be more efficient with the way that we do that is a big focus of our team. We've done some work with swabs that we use at airports. You've all been had your hands swabbed at airports. This was some work with Brian. What's interesting here, these are all different surfaces, plastic, aluminum, plastic, cardboard, and vinyl. This is the effectiveness of different swabs at getting residues of explosives off of those materials. What you should be worried about is everything underneath this bottom line is a residue that we don't detect. So 25% of the time, we will just barely detect a 20 micron diameter explosive particle. That means 20% of the time we'll miss it. So we'll swab right over that explosive on the luggage and not notice it, and that luggage goes on the airplane. Over here, I guess over here is about the scariest one on the rough plastic. So we wanted to do better than that. And working with Brian, we were able to do so, we made these conductive polymeric swabs that we could use, and they have this nice microscopic structure on the surface. And when we use those swabs in just a normal configuration, these are industry swabs that you can buy right now and use at the airport, getting about 30% of the residue off a surface, or our material that's flat, not structured, getting about 20% off the surface. And then here's our structured material that Brian made in his lab and that we were able to work on together, that are getting almost all of the residue off the surface. So just with some simple design, we're able to dramatically improve the safety at the airport. Yeah, that's what I just said. And then this is the last thing I'll show you. Right here, this is a little ship of explosive. And this is HMX. HMX? Yeah, HMX explosive inside. This is HTPB. It's a binder. And what we're going to do is we're going to hit that with a little sound wave. We're going to hit it with 10 watts of power at a specific frequency. This is your cell phone. That's all it is. And this is, just watch it, heats up. Wonderful. If we kept going, it would eventually detonate. And what ends up causing that to happen is, here is, this is HMX, which is the energetic material. And this is silgarde, which is basically the stuff you use to seal around your bathtub at home. It's just a rubbery polymer. And if there is any incidence of bad adhesion between the HMX and the silgarde, you get a little vibration there, and then you get a hot spot when this stuff resonates, and then you'll get a detonation. And if you do that while you're flying the F-35, you just blew your own plane out of the sky. So that's why this matters. And I'm excited to work on this with Steve Sun to try to understand what's going on. And Jeff Rhoads to try to understand what's going on and how we can optimize the adhesion of that interface to allow the munitions to be effective. And this just shows you what I just said. When we don't damage the interface, when the adhesion is perfect, we get no temperature rise. But in less than four seconds, if there's any kind of debonding, we get substantial temperature rise on our way to a thermal excursion and an explosion. This is work that Jason does, and we don't allow explosions to occur, so we stop after four seconds. And now we'll finish up with the Purdue Energetics Research Center. We're starting off designing molecules, formulating them into explosives, developing new ways to manufacture them. We're planning to build a pilot plant out at Westgate near Crane. And then finally, we're going to demilitarize energetic materials that are no longer useful. It's going to be a comprehensive center of excellence. We're hoping to achieve $100 million center using the players on our team to impact the way that munitions are treated and handled across the military. So with that, we'll thank NSF, NIH, Homeland Security, CTTSO-TISWIG, Purdue, and Arizona State for supporting me all this time. And then we'll also thank those wonderful people for tolerating me while I was doing all of this stuff that I was talking to you about for the last 40 minutes. So thank you so much for being here today. I hope you found this to be interesting. If I've got time for questions, I'll take them. That was Disney World, by the way. Yep, Sydney. Well, it's an excellent question. So I'll answer it this way. When I'm in the classroom with my students, the most important thing that I can do is teach them the content that is to be transferred. And so in that setting, I don't want to do anything that distracts from the students learning the content that I'm presenting. In a separate setting, if I want to help those students to learn how to engage others and work together, I can have that be the primary focus to help them work on that part. But to expect them to learn the challenging content while also learning how to engage socially something that is really very, very difficult for them makes both things much more difficult and makes you much less effective at both. So I personally believe we should optimize the classroom for people's learning and then help them work on the anxiety or the other challenges that they have outside of the classroom where they can focus just on that part. That way we're going to do the best possible job on the two pieces. Working with industry is a different piece. It's very difficult because many of these students don't want anyone to know that they're not neurotypical. And so they won't ask for assistance. They won't point themselves out when they're out there because the last thing they want is to be different. And we can't tell industry this student right here is someone you need to give a little. So I don't have a good answer for how to help those students with that transition except to prepare them as well as possible while they're here. Can you ask me again? We can use any powder. We can use polymers. We can use sand. Silica we used. We are going to use explosives powders. We're going to use particles of pharmaceutical material. It doesn't matter what we have for a powder. In fact, one of the interesting things we can do is turn the plates around. So instead of the particles coming off, the particles get driven on. And then we can cause them to deform under load, those that will deform. And we can look at the mechanics of the particles and how the contact mechanics influences the removal. But the challenge with the method is simply can you see the particles? So that limits us to 10 microns to 100 micron particle size because we're using an optical microscope right now to see them. Oh, Jim, it's a really good question. And my experience is that if we prepare the students as well as possible technically and we have programs that can prepare them as well as possible socially, we're giving them the best possible chance to succeed. I don't think that we minimize the stress they're under. I certainly see them in my office falling apart all the time from the stress. I don't think that separating what we're doing is reducing their preparation. I think it's actually giving them a better chance to be prepared. Now, giving them guidance upfront about what's going to be expected out in the field, what the industry is going to want from them, I don't know how well we do that. I don't think we actually do that particularly well. And perhaps it's something that we should do better so that they should self-select whether they want to try to go out into a particular industry or not or a particular discipline or not. But in terms of the best way to prepare them technically and the best way to prepare them socially, I think that if you force them to do both at the same time, you're making the problem just simply twice as difficult. I don't think that that necessarily leads to any better outcomes. But we can disagree if you would like. Sang. The undergraduates need a lot more coaching. They don't necessarily under... I'm usually teaching at the sophomore level. The undergraduates that I'm teaching don't know how to be students necessarily yet. Many cases they've never been challenged. They've never failed at anything. There's never been anything that was too difficult for them. And so it's a lot more coaching and mentoring with the undergraduate students. With the graduate students, I feel much more comfortable challenging them. And I don't feel like I need to provide as much of a nurturing sort of environment. But there are still cases depending on where a student had their undergraduate experience. When they arrive in Purdue Chemical Engineering, they now finally hit that wall. And so it is still important to be sensitive, but it's a lot more coaching and a lot more personal investment at the undergraduate level to help the students. Because my experience is the ones who succeed are the ones who learn how to be students fast and how to take ownership of their education fast. The grad students generally already know. Sure. Well, first, I haven't developed them. These people over here developed those tools, but I enjoy using them. Right now, I'm getting ready to use, I haven't confirmed with my colleague with whom I'm co-teaching in the fall. But there's a really interesting gamified quizzing software that I was hoping that we would implement. Where the students, I've already put together where the students take quizzes on the Chemical Engineering content. And as they get questions right, their avatar moves up the leaderboard. And when they get lots of questions right, they get bonus points and they move up and they move up. And the idea is to get them competing with each other to go do more homework problems, extra homework problems to cause their avatars to rise. And they've done a very nice job of having the avatar, the avatar is a color and a characteristic in an animal. So the avatar is the majestic purple dragon. My avatar, they somehow assigned to me the insipid puce slug. I don't know how they did that, but that is the avatar I got. But nevertheless, you wanna see your avatar moving up. And so it's a way that students work extra problems at their own pace just to compete with each other in sort of a video game style environment. When I showed that to my class last semester, they were all over it, they wouldn't pay attention to me, they wanted me to leave that up cause they wanted to push their characters up the board. So I'm excited to see how that will work. I'm using something called solstice right now, which I particularly like. It's not something we've developed here at Purdue, but it allows me to ask a student, just take a picture of your work on your phone and then I can throw that work up on the screen. So I can have, I can actually show student work during class and they just, as long as they have a smart device to take a picture and bam, it's up on the screen and we can talk it through. And then I can go to the next and the next and the next. That one makes it really easy to have the students do work in class and they don't have to go to the board. I can have five different examples in the queue and just flip through them. So I'm particularly liking solstice right now and I'm also really excited about circuit, which is just about to come out. It's where students learn how to grade quality work, you grade some work and they see what it is to grade the work and then they grade their peers work and then they regrade their own work that they handed in. And so after grading a good and average in a poor example of some content and then grading three or four of their peers work and then their own work, they know that content really, really well. And so I'm excited about what we might be able to do with circuit. I'm co-teaching and I haven't had a chance to talk with my colleague about wanting to implement that, but I've just been exposed to it from the team showed me and I'm really excited about what that might do. So those are the ones that really have my attention right now.