Dr. Stephen P. Beaudoin – Faculty Colloquium

Dr. Stephen P. Beaudoin – Faculty Colloquium

August 17, 2019 0 By Stanley Isaacs


– All right, 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. And, 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 Beaudoin for this Celebrating Faculty Success talk. A few words about Steve. He got his undergraduate
degree at MIT in 1988, Master’s 1990 at the
University of Texas Austin, and his PhD also in chemical engineering, all three degrees in chemical engineering, at North Carolina State in 1995. And, he’s been the
recipient of so many awards that I literally have to look up my notes to tell you what they are,
but it’s a long list, but, it starts certainly with
the NSF Early Career Award. He’s been named Purdue
University Faculty Scholar, Purdue University Provost
Fellow Inaugural Class and he’s 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 for Purdue’s College of Engineering, the 2017 Shreve Prize for Outstanding Undergraduate Education in Purdue School of Chemical Engineering, and the pièce de résistance, the 2017 Potter Award
for teaching excellence from the Purdue College
of Engineering, which is the highest distinction for
teaching in the college. Professor Beaudoin’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’s earned. His research has focused
really on particulate adhesion in many contexts. Started from the microelectronics
industry at first, moved onto pharmaceuticals, and then it’s moved now to
a much more energetic space. So, without further ado,
let’s welcome Steve. (audience members applaud) Thank you. – Well, 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 gonna turn the
lights down a little bit, ’cause the graphics will
show up a a little better. And, let’s just get started. So I wanted to choose a
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 gonna go over both of those kinds of things today. A little bit of 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. Okay, so you’ve all seen City Slickers and there’s Mitch there on the right and Jack Palance, Curly
the trail boss on the left. And he asks Mitch, “Do you
wanna know the secret of life?” And of course Mitch says yes. And then, Curly says it’s “This.” To which Mitch responds, “Fingers?” (audience members laugh) To which Curly responds,
“It’s one thing … “Figure that out and everything
else is just … math.” (audience members laugh) It was 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 Raupp, 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 spent five
minutes with Nick Delgass you would know that Greg
was a Delgass student ’cause it almost sounds
like the same person talking with the same philosophy. And 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 in 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 Pekny taught me how
to do 17 things at one, (audience members laugh) 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 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. 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. Lynne 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 about that later on. It’s a pleasure to work
with Bryan on some projects where we use engineered macro molecules, if 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 it appears right there. (audience members laugh) 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 gonna 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,
so I’m gonna spare you that. And then it’s been a pleasure
to work with Steve Son on a new project
associated with hot spots. And that has to do with explosives and moments you hear about
hot spots 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 studied, and I should mention Dan Hurlimann. 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 ’cause 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 and you can’t go more than
a mile in any direction without running 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. I told you we glued particles
onto AFM cantilevers. 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 used regular
old AFM cantilevers that are made rather precisely in terms of the head of the cantilever. And then we measure the
force when the cantilever comes into contact with a surface and is pulled out of
contact with that surface. And what we get is, if
we contact a cantilever against a surface a thousand times, we’ll get a distribution of
adhesion forces like this one. Sometimes the roughness on the cantilever 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’ve put on the surface. They’re not always perfect spheres. So this is an alumina particle and the software we use
is called PhotoModeler, and the way that works,
it’s the same thing that archeologists use when
they find bone fragments in the desert and they put node points on and they grid the stuff out and then they put the nodes back together and they make a 3D wireframe
mesh of the object. And you need to take pictures with an SCM from a bunch of different angles. After you merge all of
those different nodes, we come back with a second cantilever and run that over the surface to get the nano-scale
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 let’s 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. It allows us to simulate touching a surface in
many different locations just computationally, rather quickly. That’s a helpful thing to be able to do. What we’re gonna 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 gonna discretize
both the particle and the surface into nano-scale 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 tantalum oxynitride with our predicted
distribution of adhesion forces which is here in the blue. 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 nonphysical, when you randomly move the peaks around, you end up with some nonphysical
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 the 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 Yertle 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
nano-scale topography down here is what’s going to dictate the adhesion between this particle and a surface. What we found when we measured
the behavior of Yertle up against, so Yertle is aluminum oxide, we measured his behavior up against a silicon dioxide surface, what we found is this
bi-modal distribution of adhesion forces. We were doing these measurements
under water, controlled pH. And these bi-modal distributions
resulted from some cases where the topography on Yertle’s feet matched perfectly with
indentations in 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 a plateau and 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 nine, the average force is about
13 or 14 nanonewtons. pH 10, it’s about 12 nanonewtons, pH 11, it drops to about 10 nanonewtons. 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. Okay, so we wanted to
explore roughness again, and, I’m sorry I’m gonna show
you very, very few equations and this is one of them. It’s just simply a sine wave. So we’re gonna do sines
in both X and Y direction. We’re going to describe the amplitude and the
wavelength of the sines and we’re gonna 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 a 50 nanometers sphere. It’s gonna have five
nanometer roughness height. And the wavelength is
gonna 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 a order of
magnitude and a half lower from a 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 gonna become a problem. Let’s talk about inhomogeneous
surfaces for a few minutes. Here’s my particle. It’s in touch with a surface. And now this surface is
going to have all kinds of different layers that have
different composition. 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 you wanna 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 co-axial behave. There’s 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 it at its
interaction force with one atom and another surface and sum
between all of the atoms and you can do that. And that’s the most rigorous way to do it that just takes forever. We were looking for something faster. We wanted an analytical
or approximate approach. 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, let’s back up. Let’s back up again. If you take that same finite
cylinder and then you go with 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 co-axial cylinders. If you do the same thing now, if you take a cylinder against the, a small one against a large one, a small one against a
slightly smaller one, and you subtract those, you get
a cylinder against a toroid. Then if you break that toroid up into a whole bunch of other cylinders, now you have off-axis. 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. You see the agreement
is really outstanding. Then if you wanted to look at
the co-axial 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 five nanometers. You see the exact model in red,
and our prediction in blue, line up really extremely well. So, these sort of simple
geometrical models that run for 20 minutes
on a desktop computer let 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. 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 that
floated down and 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 ’cause 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 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 gonna get
dragged to the interface. The particles are gonna tend, if they can see the interface, from an electronic perspective,
they wanna 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. So we can predict that. That was very useful for the people in the
microelectronics 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. 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. For single particles we
can describe the 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 a AFM that costs $750,000 and I didn’t buy that. Purdue had that for me and I’m grateful. 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. Let’s talk about making
it stick in the classroom. Teaching effectively or making it stick. The great Rich Felder told me once that “If you really think
about it, students are remarkably like people.” (audience members laugh) 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.” (audience members laugh) No offense to any of you who were invited to the
dance in high school. (audience members laugh) But my guess is, you weren’t
expecting to be invited. What I’m trying to point out here is, that there is 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 and that’s the point I wanna make. So let’s meet your professor. We’re in academia because
it 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 self-selected those of us who could read the book and
figure it out for ourselves. It self-selected people who
could learn sequentially because that’s the way the
lectures are presented, right? We derive and then we derive
the next and the next, and as 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 outta the gate. We’re pretty good at one task at a time. We’re not so good, unless we’re Joe Pekny, at more than that. And it’s unlikely that we had any significant learning challenges when we were coming up thorough 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 and 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 RadioShack, I can’t remember what it was, showed up, and we had like six of them on a bench, ’cause we had a computer room. It was awesome. The young faculty here have always had PCs and
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. 30 seconds later he was
surfing the internet. And 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 sent 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, it doesn’t work, quit. Try, 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 a hundred times,
you try two hundred times. You finally beat the Big Boss, you move onto 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 lotta
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 mean I have conversations with my son and he never looks up from
playing a game on his phone. I ask him, did you hear anything I said, and he repeats back everything I said. They multi-task much
differently than we ever did. K-12 has improved and students
with learning disabilities get here now. They did not, in great
numbers, in the past. That does make a
difference to our teaching, and it will make a bigger
difference going forward in our teaching. If we wanna 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. Learner-focused instruction
is what I try to do and it seems to be effective and I advocate that for my colleagues. We try to have active sessions
throughout the lectures. I’ve co-taught with several
people here in the audience. 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. Ten years ago, it was active learning, put them all in groups. Those students who had those
kinds of challenges were, we just made their lives
absolutely miserable. 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’ll never wanna pair
up with anybody else. 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 wanna 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? 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’re, 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. I’ve talked about minimizing barriers between faculty and students. 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. (audience members laugh) So, students are gonna
work in a global community. Students 25 or 30 years ago maybe thought they were gonna 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, okay, 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. 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. 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 and 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. 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. Okay, 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. (audience members laugh) Although, I’m afraid one day they might. But the point is, to get
them to realize that, okay, people have this. I look at them and say, I take three pills more
every morning than you take. Big deal. Who cares? What ends up happening is that the students get the courage
to go get assistance. Every semester, two or
three students from my class will come and see me and
say, I went over to CAPS. 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 gonna 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 couple a 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 gonna
get a grade in my class. 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. Let’s get back to research. Let’s talk about polymers
adhering to crystals. This is a representation of the solubility of drugs that are in our drug pipeline. Very soluble out here is great. Bioavailability is very high. You take 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 or, No therapeutic value at all. That’s where most of the
medicines in our pipeline are 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. 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. 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 wanna become crystalline. We did some experiments here
with a rotating disk 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. We put a crystal of a
pharmaceutical ingredient on the surface there
and we’re gonna look at how that crystal grows or doesn’t grow. 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 disk. The rotational speed to the 1/2 power is the key, is the magic
feature of this apparatus. 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. In this region right here,
whereas you spin the disk 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. 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. No matter how fast you rotate the disk, you don’t increase that rate anymore. This is where we wanna
look at what’s going on because this allows us to
understand the kinetics, the process of growing a crystal. We did that with Felodipine, which is a anti-hypertension drug. This is a concentration
of Felodipine in solution as a function of time with
our rotating disk apparatus and it’s dropping here and
we have pure Felodipine because the Felodipine’s
leaving the solution and it’s growing on the crystal. So the concentration in
the solution’s going down. When we do the same
experiment, but we use, okay, get this right, darn it, H-P-M-C-A-S, hypromellos, hypromellos, 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’s the way the solution
concentration stays high. So we know that the polymer does something to prevent the growth of the crystal. Now we wanna understand what it does. Here’s our experiment that
I showed you a moment ago. This is with Filodipine 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. Then down here, when we put the HPMCAS, the integration rate is lower
by about a factor of three. So it’s slowing down what’s
happening on the surface. We can see that. 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 one, it means the polymer is effective
at stopping the growth. At low pH, it’s reasonably
effective at 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 Filodipine molecule and this is the HPMCAS molecule and it’s got all of these
carboxylic acid species in it. At the higher pH, those
tend to deproteinate and, so now you have all
these charged species and, instead of all hanging out together, they flop out in space like starfish. 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. So let’s take a look at that. This is the AFM work
that we did in my lab. This is no HPAMCAS present. This is just growing crystal and you see we got a
nice crystal face here. It’s nice and smooth and flat. We’re growing crystals of the Filodipine. Now at pH three` with the HPMCAS in there, you see all this little speckley stuff. This is the polymer sitting
down on that crystal in little aggregates. It’s like we sprinkled
salt on the surface. So there’s all little balls of polymer. Then when 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, it looks like
fried eggs on the surface. I’ll show you what that looks like. Here is the cross-section at pH three, of one of those bumps that
I just showed you here. Any one of these bumps. Characteristic size is
it’s about five nanometers, it’s about 30 nanometers in width, any one of those blobs on the surface. But if you look at pH almost seven, 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 a extended confirmation. We actually were able to
calculate, Lynne 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 confirmation which influences the
crystal growth differently. We understand how polymers
absorb onto the crystals and interfere with the growth. And now we’re working, Lynne and I, to develop ways to harness that, to change the bioavailability
of crystals in the human body. Now let’s talk about going from
single particles to powders. Powders are populations of particles, and their behavior’s driven
by nano-scale topography and micro-scale shape. If you are in the industry and you’re trying to make pharmaceuticals, you’ve got great big,
huge vats of particles and you’ve gotta figure out
how they’re all gonna 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. (audience members laugh) It’s actually not very
far from that at all. 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 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, okay. We might not even make
large quantities of it and we certainly don’t
wanna be beating it up because that might not be pleasant. So we have to understand how to use small quantities of material to understand how a
large powder will behave. So we use the centrifuge to do this. We put particles on a centrifuge on plates that go in the
centrifuge 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’s gone. And then again, we spin it a little more and now the one in the circle’s gone, and we look at how many particles come off as a function of the rotational speed. We get a map of the adhesion force of the whole distribution
of particles in the powder. It sort of works like that. Here’s the plate and it’s
parallel to the axis of rotation. It looks like this. There’s a whole bunch of silica particles on a stainless steel plate. Then we’re gonna put those
plates in the centrifuge and spin them and then, afterwards, we got a whole lot less
particles on there. So now we’re going to quantify that and try to learn how the powder behaves. This is, that experiment
I just showed you, this is the way that
the particles come off. This is the percent remaining as a function of the rotational
speed that we observed for those silica particles on a plate. And what we wanna do is we wanna use the simplest model on earth, Sorry, this is the second equation, but there’s no more than this. The simplest model on earth to describe the behavior of that powder. This is for a perfect sphere
on a perfect flat thing and this is our force constant. If we use this model, this
is what we would predict should happen for perfect
spheres on perfect flat things instead of the reality. What we wanna do, is we wanna 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’s gonna come off, and then more, more,
more, all the way through. 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, Well, 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 do 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,
and I’m kinda proud of that, the way that that worked out. Last little bit and then I
think I’m right on time, Marsha? Is the Purdue Energetics Research Center. There’s our team up there. Davin is our, 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 pre-eminent
team in energetic materials. It grew into the Purdue
Energetics Research Center, which I’ll show you our
logo in just a moment. 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. 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. 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 defuse 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 entire 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 disbursed 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. 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 wanna control the battlefield is we have to have the 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 could do any better than the F-35, we’re not gonna be able
to put a pilot in there because of the g-forces,
the vibration, the heat. Primarily, it’s the
g-forces and the vibration. The munitions that we strap onto the F-35 were of World War II era. They’re not that much
more robust than humans. If we wanna be able to
fly a plane like that at it’s capability, an
aircraft at its capability, we need improved munitions that will be ale 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 will look at sustainability, look
at reclaiming groundwater, look at remediation when of ranges where energetics were used. Then, finally, people looking
at the entire lifecycle. 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, is 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 had your hands
swabbed at airports. This was some work with Bryan. 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 is about the scariest
one, on the rough plastic. So we wanted to do better than that, and working with Bryan,
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. When we use those swabs, in
just a normal configuration, these are sort of 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 Bryan 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 were 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 chip of explosive and this is HMX, HMX? Yeah, HMX explosive inside,
this is HTBB, it’s a binder. What we’re gonna do is
we’re going to hit that with a little sound wave. We’re gonna hit it with 10 watts of power at a specific frequency. This is your cell phone. That’s all it is. This is, just watch it. Heats up. Wonderful. If we kept going it would
eventually detonate. What ends up causing that to happen is, here is, this is HMX, which
is the energetic material, and this is Sylgard, which is basically the stuff you use to seal
around your bathtub at home. It’s just a rubbery polymer. If there’s any incidence of bad adhesion between the HMX and the Sylgard, you get a little vibration there, and then you get a hot spot
when this stuff resonates and then you’ll get a detonation. If you do that while
you’re flying the F-35, you just blew your own
plane outta the sky. That’s why this matters. And I’m excited to work
on this with Steve Son, 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 at that interface to allow the munitions to be effective. 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 de bonding, 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 gonna demilitarize
energetic materials that are no longer useful. It’s going to be a comprehensive
center of excellence. We’re hoping to achieve a
hundred million dollar center using the players on our team to impact the way that munitions are treated and handled
across the military. With that, we’ll thank NSF, NIH, Homeland Security, CTTSO/TSWG, 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. – [Emcee] Oh, yeah, good. (audience members applaud) – That was Disneyworld by the way. – [Emcee] We’ve got the
room for another half hour, so you can keep asking lots of questions. – [Steve] Yup? Sydney. – [Sydney] So, I’m very glad that there’s more tolerance and allowance now for students with
social-interaction limitations. I think it’s great. But, one of our responsibilities as staff and lecturers and professors
is to prepare students to get a job and enter industry,
especially in engineering. And currently in that industry, there’s not much space
for people like that. So, do you think it’s more important to prepare those students for that reality and force them to become uncomfortable in a way that you might not want or, to try to push industry to make
space for people like that? – 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 wanna do anything that distracts from the
students learning the content that I am presenting. In a separate setting, if
I wanna 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 is 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 the classroom where they can focus just on that part. That way we’re gonna 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 neuro typical. 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. – [Audience Member] So you
showed a centrifuge-based technique to deposit the
particle on the substrate, but which particle (speaks quietly without mic) – Can you ask me again? – [Audience Member] So you
have demonstrated a technique which is a centrifuge-based,
where the particle, you didn’t mention it
is a polymer particle or silicon particle or which particle? – We can use any powder. We can use polymers. We can use sand. Silica, we used. We are gonna use explosives powders. We’re gonna 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 method is, the challenge with the method is simply can you see the particles? So that limits us to 10 microns to a hundred-micron particle size ’cause we’re using an optical
microscope right now to see them. Oh, Jim, yup? – [Jim] (speaks quietly without mic) – It’s a really good question. 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 up front 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. 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. – [Sang] So you spent a
significant part of your lecture talking about the teaching philosophy and ideas and so on. I’m curious whether you
have some thoughts about the differences, if any, in teaching undergrads
versus grad students and your own personal experiences of how you approach a grad course
versus an undergrad course. – Yeah, the undergraduates
need a lot more coaching. They don’t necessarily, I’m usually teaching
at the sophomore level. The undergraduates that I’m teaching don’t know how to be
students necessarily yet. In 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. So it is still important to be sensitive, but there is a lot more coaching and a lot more personal investment
at the undergraduate level to help the students, ’cause 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. – [Audience Member] I
know that you’ve developed some really interesting electronic things for classroom and outside
the classroom teaching. I was wondering if you
found any of them to be particularly effective that
you’d like to tell us about. – 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, where I’ve already put together the quiz, the students take quizzes on the chemical engineering content and as they get questions right, their avatar moves up the leaderboard. When they get lots of questions right, they get bonus points and they
move up, and they move up. 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. They’ve done a very nice
job of having the avatar. The avatar is a color and a
characteristic and an animal. So the avatar is the
majestic purple dragon. My avatar, they somehow assigned me the insipid puce slug, was the (audience members laugh) I don’t know how they did that, but that is the avatar that I got. (audience members laugh) 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 os 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 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,
to the next, to 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, and a poor example of some content, and then grading three or
four of their peers’ work, and then they’re 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. 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. – [Emcee] Give Steve a big hand (audience members applaud)