Issue Date: August 31, 2015
How Tulane University’s Chemists Rescued Their NMRs From Hurricane Katrina
Marking the 10th anniversary of Hurricane Katrina inevitably leads to reflections on what was lost to the storm and floods: 1,833 lives, $108 billion in property damage, and countless personal artifacts. But among these recollections are bright spots—stories of survival, salvage, and even triumph. This is one of them.
In 10 years of retelling, the tale of how Tulane University’s nuclear magnetic resonance spectrometers survived the Katrina disaster has taken on the air of a Viking epic, says Scott Grayson, a chemistry professor at the New Orleans school. It’s the sort of story repeated in lunchrooms and at casual departmental gatherings—a yarn spun out of teamwork, quick thinking, and more than a little luck. And although memories are only so reliable a decade down the road, the heroes of this legend have done their best to piece together as accurate an account of the time as possible so that others might learn from their experience.
For Grayson, the story begins on Saturday, Aug. 27, 2005. That’s when the warning went out that New Orleans appeared to be in the path of an oncoming hurricane. People were told to plan accordingly, he remembers.
Grayson decided to wait it out for a little while. “I was thinking, ‘I’m young. I’m single. I don’t have kids or pets or anything to take care of.’ ” He awoke around 3 AM on Sunday and checked the weather. “It became apparent that things were going to be bad.”
Grayson had only just started his faculty position at Tulane in July. One student had joined his lab, and his first order of chemicals had arrived, but operations were really just starting up. He had met with another prospective graduate student that Saturday. “We agreed to meet Monday to discuss things further,” he remembers. “That never happened because on Monday most everyone was in cars trying frantically to get away.”
Sifting through his credit card statements from 2005, Qi Zhao, Tulane’s NMR spectroscopist, is reminded that he left New Orleans on Sunday, Aug. 28, eventually arriving in Houston. Before he left, Zhao installed two tanks of liquid nitrogen on the fifth floor of the chemistry building, where the department’s three NMRs—a 300-MHz, a 400-MHz, and a solid-state instrument—were housed.
Zhao’s forethought turned out to be critical to saving the NMRs. People left the city thinking they’d be back in a few days, Grayson explains. They had no idea it would be more than a month before they could return to their homes.
Hurricane Katrina struck the Gulf Coast on Monday, Aug. 29, 2005. Many of the levees and flood walls protecting New Orleans failed, and the city was flooded with as much as 10 feet of water in some places. Parts of Tulane’s campus, in a neighborhood known as Uptown, were flooded. Water seeped into the basement of the chemistry building.
For most of Tulane’s chemistry faculty, the week after the storm was chaos. Some had evacuated the city, driving many hours away to find accommodation. Those who lived outside New Orleans city limits did not have to leave their homes, but many were left without electricity or running water. Downed trees made travel difficult after the storm.
Grayson drove to his hometown of St. Louis and remembers spending much of the first week of September 2005 trying to track down his Tulane chemistry colleagues. “When you’ve evacuated from a hurricane, how do you get in touch with your department chair or your best friend or anybody?” he asks. The storm had knocked out all the cell phone towers, effectively rendering the New Orleans area code nonexistent. No one was home to answer landlines. Tulane’s e-mail system had been wiped out.
Grayson remembers there being an information void in those first days after the storm. “It was nerve-racking,” he says. “You knew they evacuated the city and that there was destruction, but you didn’t know if your house still stood. You didn’t know if the neighbor you left behind who said he was going to wait it out was still alive.”
Then, about a week after the storm, it was announced that New Orleans would be closed to all private citizens, including residents, for a month or more. “This made all of us at Tulane nervous,” Grayson says. The university had biological samples that had to be kept cold and equipment that had to be maintained.
The Tulane chemists were particularly worried about their department’s three NMRs and a 500-MHz NMR located on the sixth floor of a neighboring building. All of these spectrometers, each of which cost more than $1 million, were equipped with delicate superconducting magnets that could become damaged or destroyed without vigilant maintenance.
“Superconducting magnets use coils of special superconducting material that has almost no electrical resistance,” explains Razvan Teodorescu, an expert in NMR magnets with Bruker BioSpin. Because of this ultralow resistance, scientists can run one of these magnets at a high current to obtain high field strength and, in turn, achieve high sensitivity and resolution in their data.
But, Teodorescu explains, superconducting materials operate with zero resistance only if they are extremely cold, roughly –269 °C. To achieve this chilly temperature, the magnet coils are immersed in a bath of liquid helium. To decrease consumption of liquid helium, the magnet is nested, like a set of Russian dolls, in several insulating layers, one of which is cooled with liquid nitrogen to a temperature of –196 °C.
Under normal operating conditions back in 2005, liquid nitrogen would generally last no more than two weeks, and liquid helium would last three to four months.
“If you have an event like what happened during Katrina, and you cannot access the magnet, nitrogen is the first to go,” Teodorescu says. Once the liquid nitrogen boils off, the rate at which the magnet loses liquid helium speeds up tremendously. When the supply of liquid helium gets low enough to expose part of the magnet’s coils to ambient temperature, the magnet loses its superconducting state, becomes resistive, discharges, and undergoes what’s known as a quench.
A quench can cause catastrophic damage to an NMR magnet, Teodorescu says. And repairing a quenched magnet can easily cost upward of $100,000.
With this in mind, Joel Mague, the chair of Tulane’s chemistry department, tracked down Zhao in Houston and asked him to join a skeleton crew heading to Tulane to save the magnets.
Zhao tells C&EN that once he learned he could get back to New Orleans—sometime around Sept. 8—he wasn’t particularly worried about the magnets because he left them with liquid nitrogen reserves. The instruments’ liquid helium had been filled at the end of July. “When I left New Orleans, the helium level was still about 70%,” Zhao remembers. “This saved the NMRs.”
Arriving at Tulane during that first visit—one of three he’d make from Houston that month—Zhao recalls entering the chemistry building with at least four police officers. No one was certain that squatters hadn’t taken up residence there. Zhao remembers leaning against the wall in the stairwell while the officers made sure the building was safe to enter.
Once he got the “all clear,” Zhao refilled the liquid nitrogen in the chemistry department’s NMRs. Having gone about 10 days in New Orleans’s steamy September temperatures, (without power, there was no air-conditioning) all the liquid nitrogen in the magnets had evaporated.
The following week, Gary McPherson, a chemistry professor and an associate dean, arranged for the chemistry faculty and staff to join a larger convoy visiting the campus. Grayson drove 10 hours from St. Louis to join the group, which also included Zhao; chemistry professor Russell Schmehl; chemical engineering professor Vijay John; James Peel, an NMR service technician from Bruker; and a handful of other faculty members.
The team met during the morning of Sept. 15, 2005, at Tulane’s primate research center, on the north shore of Lake Pontchartrain. To see it on a map, the lake looms like a giant storm cloud over New Orleans. The 24-mile-long Causeway Bridge provides quick access to New Orleans from points north.
With an escort of armed National Guard troops, the convoy sped over the Causeway Bridge into the city. “Words cannot describe what New Orleans looked like at that point,” Grayson says. “Most of the city had been underwater, so everything was covered in mud. Cars were turned over. There were boats parked in the middle of the highway because when the water receded, that’s where they dropped.”
When the team arrived at the chemistry building, they found it eerily dark. “It was creepy how pitch-black the corridors were even though it was broad daylight outside,” Grayson recalls. “The other thing that cannot be exaggerated is the smell. It was so hot and damp in the building, and it reeked of decay. Keep in mind the biology department was in the building, and it had been more than two weeks since anybody had been in there.” There were dead animals and chemical fridges that had warmed to room temperature. “Lab ventilation had been shut off for weeks,” Grayson says.
Carrying flashlights, the team made its way to the NMRs and found that Zhao’s prestorm planning and earlier visit had left the chemistry department’s instruments in good condition.
Assessing the 500-MHz instrument in the neighboring building proved to be another matter, McPherson recalls. It was behind a locked door that was controlled by a keypad—rendered useless without electricity.
Knowing about this security lock, McPherson decided to bring a crowbar from home. “I was sort of proud of myself for thinking of it,” he says. “At first I tried to pry the door open, and that didn’t work worth a doodle. But the door had a little window, so I beat the window in and reached in and opened the door.”
Watching a dean destroy school property doesn’t happen every day. For posterity, John snapped a photo of McPherson just before he bashed the window in.
Peel checked the NMRs’ cryogen levels and found that although the nitrogen needed topping off, the helium was still okay. Now the team had a decision to make: Keep the NMRs going, or discharge the magnets in a controlled manner and bring them up to room temperature.
As long as the school had access to liquid nitrogen, which it did, they could keep the instruments running. But just because they had liquid nitrogen didn’t mean they’d be able to get it to the NMRs. Without electricity, the elevators didn’t work. During that visit, the team used a cherry picker to lift a tank of liquid nitrogen to a terrace with access to the 500-MHz instrument, but that was a solution no one saw as safe or sustainable.
The team weighed its options. Discharging the magnets wasn’t a trivial operation. It would take some sort of power source—a car battery, for example. And without liquid helium on hand, they couldn’t be sure the magnets wouldn’t be damaged in the process.
After talking with the National Guard troops on campus, the team learned it could have access to portable, gasoline-powered generators. These could be used sparingly to run the elevators to deliver the liquid nitrogen. This, they decided, was their best option.
Zhao made the trip from Houston to New Orleans once more in September to refill the liquid nitrogen before finally returning to his home near the city in October. Chemistry professor Harry Ensley, who did not have to evacuate, took care of the instruments when Zhao wasn’t there.
By October, electrical power had returned to the school, making it easier to get the liquid nitrogen to the instruments. But another crisis was looming: The instruments were running low on liquid helium, and McPherson couldn’t find anyone who could get a supply of the stuff into New Orleans.
“At one point, I was afraid that I had made the wrong decision,” McPherson says. “When the helium was about to run out, I thought, ‘Geez, we worked so hard and saved them for three months only to lose them at the end.’ ”
But luck still had a part to play. Ensley, it turned out, had a neighbor who worked for a company called Industrial Welding Supply. Now retired, Ensley recalls telling his neighbor about the chemistry department’s problem: “He said, ‘I can get you whatever you need.’ ” A few days later, a 200-L tank of liquid helium arrived on Tulane’s doorstep. McPherson still has the receipt, dated Nov. 11, 2005.
Tulane reopened to students on Jan. 17, 2006. “If you walked across the Tulane campus, you could forget that Katrina had ever happened,” Grayson says. “Step 2 feet off campus, and that impression disappeared immediately. It was apocalyptic for months and months after they reopened the university.”
The chemistry department didn’t suffer any extensive losses to research. The biology department and researchers at the medical school were not so lucky. McPherson says he didn’t even think the story of the NMR rescue was noteworthy until he learned that every other university in New Orleans with superconducting NMRs had lost their magnets to quenches.
As for lessons learned, the school now keeps a large stock of liquid nitrogen on hand during hurricane season, and it has a much more detailed emergency plan. Most faculty have an emergency contact number outside New Orleans and an additional e-mail account that’s not linked to Tulane.
“Anybody who went through Katrina divides their life in half,” McPherson says. “There’s pre-Katrina and post-Katrina. I try not to think about the misery and sadness. For me, there’s a certain amount of pride in having been involved and in doing the best I could.”
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