“The target vessel is a steel structure containing 50 tons of swirling liquid mercury. During neutron production 60 pulses of protons collide with the target vessel releasing energy roughly equivalent to a stick of dynamite exploding every second. When high-energy protons hit the nucleus of a mercury atom, 20 to 30 neutrons are “spalled” or released. Those neutrons are guided into beam tubes attached to instrument stations. The neutrons coming out of the target must be turned into low-energy neutrons suitable for research—that is, they must be moderated to room temperature or colder.”–Oak Ridge National Laboratory
Oak Ridge National Lab biophysicist John Katsaras chaired one of the sessions earlier this year at the National Science Foundation conference, “Progress and Prospects in Neutron Scattering for the Biological Sciences,” and he has been working in the neutron science field for a quarter century or so—both in the US and Canada. However, unlike the NSF’s May symposium on synthetic cell development—whose video presentations were posted online—the public remains largely in the dark about what transpired at the NSF neutron science meeting last February. Katsaras tells me we can expect to see the NSF neutron scattering and biology report sometime early next year.
Probing material with neutrons—neutron scattering—enables minute and precise measurement of structure and function without damage to even living material. So why all the suspense?
The insight of science and technology historian David F. Noble is relevant here:
“By about 1943-44, there was a discussion about what the postwar scientific establishment would look like. . . .Vannevar Bush and his friends put together a counterproposal calling for a “National Research Foundation”—which became more or less what we have in today’s National Science Foundation.
The Vannevar Bush et al. legislation said essentially that science would be funded by the taxpayer but controlled by scientists. Again, scientists—this is important to emphasize—are not simply scientists, but scientists and the corporations they work for.”
So NSF may be trying to figure out exactly what to say in its 2019 report to the American people. Indeed, there are sensitive points.
One—the Oak Ridge, Tennessee facility—Spallation Neutron Source—which at the moment is the largest spallation source in the world (26 neutron scattering instruments and beam lines) is expanding from 1.4MW to 2MW to be more competitive with the European Spallation Source (ESS) in Lund, Sweden, which is designed to eventually be a 5MW facility (it’s 48% complete now). The projected MW numbers in both cases seem to be somewhat fluid. The US is also planning a second target station, it’s unclear where.
Two—Oak Ridge currently uses “50 tons of swirling liquid mercury” in its spallation process. And expandintg power will require dealing with the current limits of its steel vessel in order to prevent mercury leaks. Mercury pollution is a global environmental problem, causing nerve damage, in particular, across the spectrum of life.
The Swedish ESS facility does not use mercury and seems to have met the demands of Europe’s environmental community.
Construction began in 2017 on a mercury treatment facility at the Oak Ridge Y-12 National Security Complex, which was formerly used for H-bomb production. The Washington Post noted in 1983 that DOE reported 2.4 million pounds of mercury missing from Oak Ridge over a 13-year-period beginning in the 1950s, which had most likely escaped into the pristine Tennessee countryside. When completed in 2024 the treatment center will apparently help to reduce the amount of mercury released from the demolition of Y-12.
But what about the mercury factor at SNS? Should the Oak Ridge facility be redesigned along the lines of the more environmentally friendly ESS? We will probably have to wait for next year’s NSF report to see if that’s even on the boards for discussion.
Three—the High Flux Isotope Reactor, which provides a steady stream of neutrons for scientific research at Oak Ridge still uses highly enriched uranium to do so. The scheduled move from weapons-grade to low-enriched uranium doesn’t happen until sometime in 2020.
Meanwhile, I decided to ring up John Katsaras at ORNL to discuss his research on cell membranes using neutron scattering. Last year Katsaras and colleagues at ORNL were successful in carrying out the first direct nanoscale investigation of a living cell membrane, finding that lipids gathered with other lipids of their type within the cell membrane to form “rafts.” These rafts or domains help facilitate cell-cell communication but are too small to be seen using standard optical instruments.
Coincidentally, as I write, John Katsaras is moderating a panel discussion at Lund Institute of Advanced Neutron and X-ray Science on “Dynamics of Membranes and their Constituents.”
John Katsaras is “Senior Scientist Biological Systems/ORNL Distinguished R&D Staff, Large Scale Structures Group, Neutron Sciences Directorate” at Oak Ridge National Laboratory. He is also on the faculty at the University of Tennessee’s Bredesen Center for Interdisciplinary Research and Graduate Education as well as UT’s Institute of Biomedical Engineering, and a professor in UT’s Department of Physics and Astronomy. Katsaras is an adjunct professor in the physics department at Ontario, Canada’s Brock University St. Catharines.
He holds two patents with several others pending.
Among his honors are: Fellow, Neutron Scattering Society of America (2018); Fellow, American Institute for Medical and Biological Engineering (2018); Oak Ridge National Laboratory, Significant Event Award (2017); NRC/Steacie Institute for Molecular Sciences, Annual Award for Improving Life in the Institute, Canada (2007); NRC/Steacie Institute for Molecular Sciences, Outstanding Achievement Award, Canada (2001, 1999).
As a Canadian—he adores the Tennessee outdoors. And his fascination with acceleration is evident even in his avocation—collecting racing bikes.
John Katsaras first studied psychology—BA, Concordia University, Montreal—and then biology —BSc, Concordia. His MSc and PhD are both in biophysics from Canada’s University of Guelph. He was a postdoctoral research fellow at Guelph (with R.H. Stinson and J.H. Davis) and at McMaster University (with R.M. Epand) as well as a post rouge fellow at CRPP-CNRS (with J. Dufourcq) in France.
My recent conversation with John Katsaras follows.
Suzan Mazur: Neutron scattering has been around for a while, why all the excitement now? The Europeans have formed LENS (League of Advanced European Neutron Sources), and Sweden is building the next generation spallation source with apparently unprecedented brightness at Lund University (48% complete). Oak Ridge National Laboratory is expanding its facilities. There are also upcoming conferences on neutrons and biology. Why all the excitement?
John Katsaras: Neutron scattering is comprised of many different techniques, each requiring its own approach—one can say that about other techniques, such as microscopies. As far as biology is concerned or soft materials, the real excitement is that you can probe these materials at the nanoscale. We’ve shown here at ORNL that you can probe cells when they’re living with nanoscopic resolution.
Currently there are no other techniques that can accurately probe living materials at the nanoscale. There’s a lot of debate about that. To the best of my knowledge, neutron is the only one, as we’ve demonstrated here.
Moreover, there are very few techniques period that can probe soft materials on the nanoscale in a disordered state. When you crystallize things, there are scattering techniques that can be used, for example, electrons and x-rays. But when material is not crystallized, neutrons have a distinct advantage.
Neutrons also come in different flavors. You can look at static structure. You can also look at dynamic structure. In static structure you are studying the time averaged structure. In the case of dynamic structure, by definition things are moving around and you are capturing snapshots of the structure. So with neutrons you can study a range of things from—collective motion—molecules moving together in some synchrony, or individually.
Suzan Mazur: Thank you. Cytogeneticist Antonio Lima-de-Faria from Lund University, where they’re building the European Spallation Source, refers to “enormous accelerators of electrons and neutrons elucidate[ing] DNA’s own evolution—determination of exact position and movement of atoms.” Do you agree with that?
John Katsaras: I agree in the sense that you can observe how DNA’s structure evolves in real time as a function of changes in temperature, pH or ion content, for example. Depending on the timescales, which can range from fractions of a second to hours, these kinetic measurements can be done with x-ray and neutrons, although neutrons are better able to capture the slower kinetics due to their lower flux compared to x-rays.
Suzan Mazur: Lima-de-Faria has also said neutrons can probe matter including biomatter enabling measurements of structure from micrometers to one-hundred thousandth of a micrometer plus motion from milliseconds to ten-million-millionths of a millisecond. Do you agree with that?
John Katsaras: Basically yes. You can look at things from the micron scale, which corresponds to optical techniques that provide complementary data. And then you go to angstroms with neutron crystallography. Neutrons can be understood as similar to x-rays in crystallography, where you obtain atomic positions with angstrom resolution, corresponding to 1 x 10 to the minus 10 meters. So, yes you can. And the dynamic information with that can be accessed with neutron ranges from the picosecond to the hundreds of nanoseconds.
Suzan Mazur: Is every structure and function the immediate product of a molecular cascade originating in atomic and electronic events?
John Katsaras: That’s a good question. I don’t know how to answer it. Of course structure has a role in how function is expressed. One such case is the so-called raft hypothesis in membranes, for example. Something we’ve been investigating here at Oak Ridge.
Suzan Mazur: That was actually my next question. Your team at Oak Ridge has done the “first ever direct nanoscale examination of a living membrane.” What can we now see that we couldn’t see without these advanced measurements and instruments?
John Katsaras: But it’s not necessarily the instruments that make the difference. It’s the approach to the problem. Sometimes there’s an overemphasis on hardware. The best hardware doesn’t always lead to the best science. Of-course you need access to the very best instruments you can find. But if you don’t have the right questions and if you don’t have the right sample, it will result in a poor or mediocre experiment. What’s needed most is a great experiment. In the membranes experiment we did here we engineered the bacteria so we could visualize its membrane, using neutron scattering.
But coming back to the question of structure and function. The way DNA is organized, for example, DNA’s structure is integral to its replication process.
Suzan Mazur: Your membranes research revealed that lipids gathered with others of their type.
John Katsaras: Right. The cell makes thousands of different types of lipids. In the plasma membrane, which is the outer membrane of the cell, there are hundreds or, maybe thousands of different lipids. The question is, why does the cell expend so much energy to make all of these different lipids.
You could say, well, maybe they have all different physical properties.. As a result, mixtures of lipids may come together to create an environment for a protein enabling the protein to perform its function.
How does this happen? Are these passive processes driven by thermodynamics or are they active processes where the cell makes these things, puts them in place, and then continues to micromanage them? This remains an open question.
Suzan Mazur: Is the Oak Ridge Spallation Neutron Source (SNS) the only neutron scattering facility in the US?
John Katsaras: Not the only, however Oak Ridge is the largest US facility—both the Spallation Neutron Source and the High Flux Isotope Reactor. There’s also the NCNR [Center for Neutron Research] in Maryland. A small facility in Missouri [University of Missouri Research Reactor]. And a spallation source similar to SNS at Los Alamos [LANSCE], although I am not sure if it is currently open for civilian research.
Suzan Mazur: Are you collaborating with Europe on investigations?
John Katsaras: I have a collaborator in Austria, Georg Pabst at the University of Graz. We’ve been developing an asymmetric membrane with a model system. Since model systems are much simpler than functional biological membranes, they allow one to get a handle on what’s going on in real systems.
It should be pointed out that membranes have two bilayer leaflets. In functional cells these leaflets are chemically different, i.e., the leaflets contain different lipids. The inner or cytoplasmic leaflet differs from the outer leaflet chemically. One can argue as to why that is.
When you make model systems you generally mix these lipids and they will always randomly distribute equally in both leaflets. The chemical makeup of that bilayer will be the same for both leaflets or very close. There may be some factors that may make the lipid prefer the inner lipid versus the outer bilayer leaflet. But for the most part, the leaflets are symmetrical.
We’ve been developing something that is asymmetric, to better mimic the biological membrane. That’s one of the things our lab is working on with Georg Pabst and his group. We’re also working with other people here within the United States and Canada (e.g., Fred Heberle, Drew Marquardt and Erwin London). This has been written up in Nature – Protocols, which will be coming out very soon.
Suzan Mazur: What does this mean for synthetic cell development?
John Katsaras: The systems that we work on are created to understand biological membranes. That’s our focus. Now, of course, you can use cells to create and encapsulate material. These are useful in industry and drug delivery. You can send them to image parts of the body. So you can develop model membranes with all these different functions.
Suzan Mazur: But do you envision down the road being able to see more and more of what is happening inside the cell to determine position, measure, etc.
John Katsaras: Scientists have done that over many years. You can do electron microscopy, for example, and look at a cell, at 10 angstroms or whatever the sample allows you. And you can look at the organization of cells at some resolution. In most cases, the cells are dead.
With living systems it becomes much more difficult to study systems with good spatial resolution. Some of the ways you can do it is optically. Then it’s a question of resolution. So people are looking at creating model cells. But as far as I know, they are almost always inert.
The other thing that’s becoming really important is the computational aspect of science, which means you now have data with which you can better understand the structure-function relationship, for instance.
Suzan Mazur: But are we closer to understanding the origin of life because of advanced neutron scattering?
John Katsaras: You can start putting the pieces together regarding big scientific questions about the origin of life, which will lead to a better understanding of what’s going on regarding disease.
Experiments have been going on for a long time regarding the origins of life. The techniques themselves are needed but insufficient in understanding the fundamental problem. In science you have to come up with an idea. The science is the idea. Technique is part of the story, but in the end, you always have to have a good idea to work from.
Suzan Mazur: What are the hazards working in the areas of neutron scattering? The use of deuterium, for instance.
John Katsaras: It’s not hazardous at all because deuterium is not radioactive, it’s stable, an isotope of hydrogen. As long as you don’t drink it. And even if you drank some of it, nothing would happen to you. Just don’t drink too much.
Suzan Mazur: Do you see the US moving more into neutron science the way the Europeans are?
John Katsaras: Well we are. SNS is a great example. ESS in Sweden will be more powerful but America is planning a second target station that will be very competitive.
Suzan Mazur: Where will that be, the second target station?
John Katsaras: We don’t know. There are ongoing discussions. If it does come to fruition, it will be tailored to look at biological materials and soft materials. If it does happen, then I would very much like to have that machine because its characteristics will be effectively maximized for the type of science I’m interested in.
[Note: John Katsaras has emailed the following update: “[The second target station] STS will be next door to the first target station (FTS) and would be ideally suited for studies of Advanced Materials, which include quantum phenomena, engineered materials, soft matter, and biological materials (for further informtion please visit: https://neutrons.ornl.gov/sts and the corresponding STS fact sheet: https://neutrons.ornl.gov/sites/default/files/STS%20Brochure%2011×17%20%202018.pdf).”]
Suzan Mazur: How long have you been working in neutron science.
John Katsaras: I’ve been involved with membranes research my entire career. I began as a graduate student in 1984. I’ve worked in neutron scattering since 1994, starting at the Chalk River Laboratories in Canada. Those are very similar labs to Oak Ridge. They were developed during World War II and the Canadians had the heavy water reactor concept, which they developed in the 40s and 50s. The first really big reactor in Canada built was called NRX—National Research Experimental. Canada then developed the National Research Universal reactor.
Suzan Mazur: You’ve seen quite a lot. Do you expect to continue with your research for some years to come?
John Katsaras: Well, I haven’t stopped. I’ve been at it since 1984 and I don’t plan to stop anytime soon. One of the reasons I came to the United States was to make sure my career could continue. Canada’s NRU reactor was shut down this year. That I knew was going to happen because the reactor became operational in 1957. The writing was on the wall as far as its longevity was concerned. Its lifespan was clearly coming to an end. That would be it. I moved to Oak Ridge in 2010.
Suzan Mazur: You were born in Canada?
John Katsaras: I was born in Greece. On the island of Rhodes. My mother and I emigrated to Montreal when I was two years old and I came to the US when I was 52. It’s been a very good place to live and work, and ORNL has experienced a revitalization of its facilities over the last 15-20 years.
Suzan Mazur: What do you expect from the research in the way of applications?
John Katsaras: I don’t think of science that way. Putting applications before science is like putting the cart before the horse. It’s important to address basic questions. From those answers all kinds of possibilities emerge. We’re too preoccupied now with technology and outcomes. Discovery happens when you least expect it. A lot of practical applications often emerge when you’re not trying to make practical applications.
Successful breakthroughs happen because you have some of the brightest people researching, scientists who are allowed to think and work on basic problems that are of tremendous interest. It’s been proven over and over, that this is the best way to do science.
Even with the atom bomb, for example. The basic physics aspect of creating an atom bomb had been worked out. The building of the bomb was the real problem. It was an engineering problem. Then, of course, the politics of the day came into play, because billions of dollars had to be found to create a device.
Suzan Mazur: Is there a final point you’d like to make?
John Katsaras: Any country that wants to be at the cutting edge of science has got to have excellent basic research. The United States has hugely invested in basic research over the years, and as such continues to attract the best scientists. Once you have such an investment in basic research, important technology flows.
Suzan Mazur: What kind of budget does Oak Ridge have?
John Katsaras: Its annual operating budget is about $1.6 billion dollars.
Suzan Mazur: That’s quite a substantial amount.
John Katsaras: And now you have China coming into the frame. It has put an enormous amount of money into basic science and is attracting a lot of Western talent.
John Katsaras: Just outside of Hong Kong.
Suzan Mazur: Do you get back to Greece?
John Katsaras: Once a year to visit my mother. I travel to Canada quite a bit.
Suzan Mazur: Do you have interesting hobbies outside the lab?
John Katsaras: I play a lot of hockey. I fish. I love history, including science history. I cycle and am a big collector of European racing bikes from the 50s and 60s, but I’m also interested in the ones Schwinn made at its Chicago factory.
The bicycle is still the most efficient human-powered machine. Roads were actually built for bicycles, not cars.
Neutron Science Facilities Worldwide:
European Spallation Source, Lund University, Sweden (48% complete)
Recent and Upcoming Conferences:
National Science Foundation Workshop on “Progress and Prospects in Neutron Scattering for the Biological Sciences,” Alexandria, Virginia, US, February 20-22, 2018
9th Workshop on Neutron Scattering Applications in Structural Biology, Oak Ridge National Laboratory, Tennessee, US, June 11-15, 2018
American Conference on Neutron Scattering, University of Maryland, College Park, US, June 24-28, 2018
“Membranes Beyond,” International Workshop on Status and Perspectives in Research on Membrane Structures and Interaction, McMaster University, Hamilton, Ontario, Canada, July 2-4, 2018
15th International Surface X-ray and Neutron Scattering Conference, Pohang Accelerator Lab, Pohang, South Korea, July 15-19, 2018
“Dynamics of Membranes and their Constitutents,” Lund Institute of Advanced Neutron and X-ray Science, Lund, Sweden, September 12-14, 2018
Neutrons and Biology Conference, Carqueriranne, France, September 16-19, 2018
High Brilliance Workshop, Cologne, Germany, October 4-5, 2018
ISIS Large Scale Structures User Meeting, Abingdon, UK, November 1-2, 2018
Gordon Research Conference on Neutron Scattering, Hong Kong, China, May 5-10, 2019
European Conference on Neutron Scattering 2019 (ECNS), Saint Petersburg, Russia, July 1-5, 2019