Stephanie L. Kwolek, inventor of Kevlar

Sixty years ago, a Polish-American chemist named Stephanie Kwolek made a breakthrough in polymers that would have far-reaching applications. The fabric material Kevlar was born in 1965 and has since been used in racing tires, sails, tennis rackets, archery bow strings, brake pads, musical instruments, and much more. It is most famously known for the life-saving component in bulletproof vests. As with many discoveries, Kwolek created the material for Kevlar in an unexpected way.

Image from Science History Institute

She was born in New Kensington, Pennsylvania on July 31, 1923 to Polish immigrants. Her father, a naturalist, imparted in her a scientific curiosity of the world as they explored forests and fields near their home and filled scrapbooks with samples from those locations. Her mother was a seamstress, and for a while Stephanie considered being a fashion designer and practiced on paper dolls and then made cloth versions. The creativity in this practice gave her a lot of satisfaction.

Paper doll figures and fashions to attach to them (Paperdoll Review)

However, that career ambition died early when her mother told her she probably couldn't make a living doing it because Stephanie was too much of a perfectionist.

In her public school, two grades of students were taught in the same room with separate lessons. But she got to hear what was going on in each, so essentially she learned two grades at the same time. 

Kwolek's elementary school building (YouTube, Women in Chemistry: Stephani Kwolek)

Next, she attended Margaret Morrison Carnegie College (now Carnegie Mellon University) with a major in chemistry and hopes of becoming a doctor after graduating in 1946. Kwolek admits to being influenced by enthusiastic Professor Clara Miller in her chemistry class. She must have done something right, because she was invited to join a panel of male chemists to discuss their work at a gathering at the university in just her first year!

Carnegie Mellon photo, from YouTube "Stephanie Kwolek"

However, she couldn't afford medical school, and instead she thought about making enough money for that by getting short-term chemistry work. At this time, DuPont was the leading chemical company in America, so it seemed logical to her to apply there. DuPont had been founded in 1802 and played a significant role in supplying munitions to the Union side of the Civil War, plus 40% of smokeless gunpowder in World War II. It also built the nuclear facility in Hanford, Washington to make plutonium for the Manhattan Project. It also produced innovative materials like synthetic rubber neoprene (1930) and nylon (1935).

When she interviewed for a job there, DuPont's research director William Hale Charch said she could expect to hear back in two weeks. She pushed back, though:

With great boldness—I would never do it now—I said to him, “I wonder if you could possibly tell me sooner because there is another company that wants me to decide whether I should come and work for them.” So he called in his secretary, and he dictated the letter to me while I was sitting there, and offered me the job. (from March 21, 1998 interview, Chemical Heritage Foundation) 

Image from PBS video

Work for women in science then was difficult because of the male-dominated culture. And, most female PhDs quit research after 2 years to transition into teaching. But, Stephanie admits to being stubborn and sticking it out because of her creative nature and desire to learn new things. Men and women were paid similar wages, too. 

Her early work at DuPont was with polymers, which are long-chain molecules. A few years earlier, materials like nylon were produced with high temperatures, so her work was intended to save energy and improve safety by using low temperatures to make the same polymers. Those made at high temperatures were flexible and soft, but DuPont was working on making tougher, more durable polymer material for things like tires. In the early 1960s, there was a fear of a gasoline shortage coming, so more gas-efficient tires were deemed necessary. 

DuPont's Pioneering Research Laboratory, 1940s 

She was then put in the laboratory of Paul Morgan where she was assigned to work on a polymer called a para-aromatic polyamide. It broke apart at the molecular level when it was melted, it didn't dissolve easily in comment solvents, and was too stiff to be spun into threads. Nobody else in the lab wanted to work on the project, and Morgan was busy writing a book, so he didn't pay attention to her work. 

Paul Morgan, Herbert Blades, and Stephanie Kwolek (From invention.si.edu)

Despite Morgan's absence, Kwolek credits all men who worked with and over her, saying that she felt fortunate they were very interested in making discoveries and inventions. In those days, you couldn't learn polymer science in school. Men and women alike "started on an equal basis ... I had to study up just as the men did. We helped each other and learned from each other. Somehow, I never set myself apart, or thought lesser of myself, because we all seemed to start on an equal footing." (quote from invention.si.edu) What's more, to her delight, they left her alone to do her own experiments even though she had only a bachelor's degree.

She worked on a specific polymer abbreviated 1,4-B (for poly-1,4-benzamide). But she couldn't just buy it off the shelf to do experiments. She had to make it on her own, including making all the necessary ingredients! 

I had a technician who helped, but because it was such an early stage, I had to work with him to observe just what was going on. I had to devise new ways of doing things as we went along. I couldn’t just give him a recipe and say, “Do this.” (From March 21, 1998 interview, Chemical Heritage Foundation)

Image from YouTube

The next step was to dissolve 1,4-B and then run it through a machine to make thread. After testing many solvents unsuccessfully, Kwolek chose to dissolve her polymers in tetramethyl urea. Polymer solutions are usually transparent and syrupy. Stephanie's, however, was cloudy as buttermilk and opalescent (showing many small points of shifting color). She thought, "There’s something different about this. This may be very useful." Her technician in charge of the spinning machine (spinnaret) refused to use it because he thought the cloudiness meant it had particles floating in it and therefore would plug up the small holes (0.025 mm, or 0.001 inch in diameter) in the spinneret. Normally, such a solution would be thrown away. 

Kwolek with a tube of polymer liquid before spinning into fabric thread (A Mighty Girl website)

But, Stephanie filtered the solution and observed no particles. So, she put some in a syringe and forced it out the needle to make a thread herself. When she heat-treated the strange thread, she measured a strong ability to resist a change in shape (deformation). So, she thought she was on to something and pestered the technician again until he ran the polymer solution through the spinning machine.

Spinning process for polymers (images from Textile Study Center and VNPOLYFIBER)

When she ran the strength (deformation) test on this material, it showed an amazing result.

• Soft rubber's value is 0.01-10 megaPascals
• nylon was 1,000-3,000 megaPascals
• her new material was 130,000 megaPascals
• in comparison, steel is 200,000 megaPascals

Kwolek showing chemical properties (left); presenting the spun fibers (right) (PBS video)

Further testing and refinements showed that the material matched the requirements of her project, that of being lightweight and heat resistant, but it was also five times stronger than steel. 1,4-B was then passed on to another section of the lab for further development. Stephanie donated some of the thread she'd made, and another scientist wove it into a vest and conducted early tests as a bulletproof vest material which later became Kevlar in 1971. Stephanie signed off her patent royalty rights to the polymer, and DuPont invested $500 million into it. It has since been used in over 200 applications.

Fibers used to make Kevlar (Wikipedia)

Kwolek continued to work at DuPont until she retired in 1986. During that time, she consulted on lab research into three other products: Nomex, the flame-resistant material for firefighters, Lycra spandex, and Kapton (a film for printed circuits and space blankets). She is the first female recipient of DuPont's Lavoisier Medal for technical achievement. (Only one other woman has received that, but it was in 2022 and in collaboration with another scientist.) 

After retirement, she not only continued to consult with DuPont, but she tutored high school students (especially girls) in chemistry. She was the recipient of several other awards and honors including 17 patents. In 2001, her alma mater Carnegie Mellon University awarded her an honorary degree.

Image from Carnegie Mellon University

Stephanie L. Kwolek passed away on June 18, 2014 at age 90. On that day, DuPont announced that they has just sold the millionth vest made from Kevlar.

This scientist developed a soap that could help fight skin cancer. He's 14.

Link to NPR interview

A teenage boy from Fairfax, Virginia, USA, has a goal to make a soap product to fight skin cancer and be affordable. Hemen Bekele won the 2024 3M Young Scientist's Challenge in succeeding to do just that. The monetary prize of $25,000 is only the beginning.

Heman Bekele (Image from TIME magazine)

From the age of 7, Heman played around at home mixing chemicals at random, and then jump-started his learning with a chemistry set. After emigrating to the US at age 4, he recalled seeing laborers working in the sun in his home of Addis Ababa, Ethiopia, usually with no protection for their skin. His move to the U.S. sparked his thoughts about putting chemistry to use:

“When I was younger, I didn’t think much of it, but when I came to America, I realized what a big problem the sun and ultraviolet radiation is when you’re exposed to it for a long time,” Heman says. (TIME).

He read about the drug imiquimod, which is used in cream form to fight skin cancer, but he was concerned about its high cost: $40,000-$56,000 (not taking into account insurance). Because places like Ethiopia depend on agriculture for their survival, Heman thought he could help by developing something cheaper and more easily available. His idea was to create a bar of soap to deliver the drug.

Heman working at home to make the bar soap.  (tpgonlinedaily.com and Heman's website)

As long ago as 2800 BCE, Babylonians knew how to make soap, by boiling goat fat with ashes. But it was used mostly for cleaning textiles. Egyptians around 1550 BCE used their variation with animal and vegetable oils used it for personal hygiene and medicinal purposes (such as treating dermatitis, infected wounds, scalp conditions and lice. From the first century, Romans spread knowledge of soap-making across Europe, North Africa, and parts of the Middle East, but mostly used oils and scrapers. After the Roman Empire fell (476 CE), Islamic cultures--centers for science and medicine--emphasized personal hygiene due to religious practices (e.g., ritual washing). They turned soap into a daily-use item, especially for personal hygiene. From the 12th to 15th century, southern Europe created trade unions to manufacture soap, but it took until the 16th century to make it cheaply enough for common use homes.

Regular bathing—especially for personal cleanliness—was uncommon in both Europe and America in the mid- to late-1800s. People just changed clothes or wiped their bodies. But links to disease promoted the use of soaps, as as moral, healthy, and civilized efforts.

Soap works as follows: soap molecules have a water-attracting (hydrophilic) and and a water-repelling (hydrophobic) end, and together, they bind dirt in chemical clumps and dissolve in water to wash away most things. 

Image adapted from (Why Soap Works, NY Times, March 13, 2020)

Strictly speaking, the high pH of traditional soap (9-10) is not good for skin, which has a pH around 4, and it tends to dry out skin by removing oils that otherwise keep moisture in. 

The chemistry of soap wasn't known well until 1823, when Michel Eugène Chevreul showed how the Sumerian concept of soap making worked. The fat reacts with an alkali (like lye), breaking it into soap (salts of fatty acids like stearic, oleic, and palmitic acids) and glycerin. Mass production of soaps was now possible through the late 1800s, but as mentioned above, personal use was still rare. Products like Sunlight Soap (UK, 1885) and Ivory (US, 1879) then became household staples. From the 1880s on, soap was now available to the middle class.

So, a commonly used item like bar soap seems like a useful method to apply drugs to the skin, where melanomas (skin cancer) develop. Heman worked with Deborah Isabelle, a product engineering specialist at 3M, to do some computer modeling and experiments to see how chemicals added to his soap would go through the skin instead of being washed off.

Isabelle and Heman at the 3M award ceremony (NPR)

Heman's award-winning soap included organic shea butter, coconut oil and moisturizing cream 3M Cavilon. He thinks it works by reactivating a type of immune system cell called a dendritic cell, part of skin tissue, which then sends a message to the whole immune system to fight the invading cancer cells. During cancer, the dendritic cell is usually inactive, which allows the cancer to take over. If Heman's soap makes them active, the body stands a better chance to fight it. 

A mature dendritic cell with its branches (dendrites) that look like nerve cells (Wikipedia).

To go beyond a bar of soap and showing a computer model of getting drugs into the body, he needed a way to test actually doing it. At a networking event hosted by the Melanoma Research Alliance, he met Professor Vito Rebecca of Johns Hopkins University and was invited to work in his lab. 

Heman and Dr. Rebecca (Instagram)

They refined the approach from the skin absorbing a drug dissolved in it, to a specific drug carrier called a nanoparticle. If you just apply the drug in a cream or soap, it has to go through the skin randomly and wind up everywhere. But nanoparticles can be tagged to enter the skin and seek out only specific cells like the dentritic cells, where they get exposed to the drug in higher concentrations.

Left, passive random drug delivery.

Right, active focused drug delivery to a desired cell. (Pudlarz & Szemraj, 2018)

In Vito Rebecca's lab, they have tested this formulation with a form of drug called imidazoquinoline. The drug itself is not new in the war on cancer; the delivery system is. They are currently testing it on mice and, if successful, will see FDA approval in about 10 years.

Heman has described his soap as follows:

"The color is a bit of a dark type of white and it has a little bit of a bumpy texture to it, which could be a good exfoliant. It does have a strong potent medicine smell to it. But of course it isn't the worst smelling thing." (NPR)

Heman's SCTS (skin care treatment soap) in its biodegradable box (MPR News and virginiamercury.com)

Ultimately, Heman hopes to mass produce his soap and create a nonprofit organization by 2028 to distribute it worldwide. At the moment, the estimated cost for one bar of SCTS is $0.50. 

Here is a short video interview from his local TV station: 

Bioengineers made mutant, solar-powered hamster cells

Link to article

Plant cells have a structure called a chloroplast. Animal cells don't. Animal cells consume food that is provided to them after the animal eats and breaks it down into simple components. On the other hand, using chloroplasts, plants make their own food from air, water, and sunlight. But what if animal cells could be equipped with chloroplasts? And why would anyone want to do that?

You may remember from biology classes that plants use the energy from sunlight to split water molecules, which then combine with carbon dioxide to form sugars that feed the plant cells. This is called photosynthesis (photo-: light, -synthesis: building). This all takes place in the chloroplast of plant cells. A by-product of this process is oxygen, which the plant releases.

Diagram of photosynthesis (modified from Alamy)

Scientists are considering how the production of oxygen inside the body could be helpful. Here are some medical examples of when it is needed more than for just the usual supply to tissues.

• In coronary artery disease, clogging of arteries that surround and feed the heart results in poorer blood supply and the oxygen it carries. Poor circulation often also occurs in patients with diabetes.
• In wounds, the blood vessels are cut or crushed, so less blood with oxygen can be delivered. Body cells sent to the injury also need oxygen, but they may not get it.
• Also, when organs or tissues suffer from trauma or disease, they need to be repaired or replaced. A special kind of science called tissue engineering can make that possible with donor cells from the body that are placed on scaffolds to grow; the structure is made inside or outside the body. Examples are small arteries, an artificial bladder, skin grafts, cartilage, and a trachea. But growing the replacement cells often suffers from insufficient oxygen.

Many methods have been used and proposed to add oxygen to areas inside the body: flooding the injury with high concentrations of oxygen, adding artificial blood substitutes that carry more oxygen, using gene therapy, or applying materials to dressings (hydrogen peroxide, nanoparticles with oxygen bubbles, nanofibers with oxygen-releasing chemicals like CaO₂, etc.). 

Some researchers have also inserted plant cells (algae) themselves!

Cyanobacteria (blue-green algae) like Synechococcus elongatus was added to rat hearts and survived 1-2 hours. The alga Chlamydomonas reinhardtii was tried on frogs and zebrafish, and the cells survived a few days. Another alga Chlorella was tested in gels or lab-grown tissues and lasted a few days to a week. 

A spongy scaffolding matrix seeded with C. reinhardtii, showing algae cells growth in the folds before implanting

(image from Hopfner et al., 2017)

Zebrafish embryo with reddish S. elongatus alga implanted in its brain

(image from Agapakis, et al., 2011)

Rat heart muscle cell with S. elongatus on its surface (image from Wang et al., 2019)

One problem other than mere plant cell survival is the risk of the body's immune response attacking these cells. So, other researchers have considered inserting chloroplasts into animals cells which can be engineered to resemble the body and fool the immune response.

In 2024, researchers at Tokyo University, Waseda University, and the RIKEN Center for Sustainable Resource Science successfully implanted chloroplasts from the alga Cyanidioschyzon merolae into hamster cells. Although chloroplast implantation had been done by others earlier in different species, this was the first time photosynthetic activity was maintained in these "planimal" cells. It wasn't long, just two days, but it was still a first.

From the researchers. Blue=nuclei, magenta=chloroplasts

You might wonder why algae and their chloroplasts have been mentioned, and not higher forms of plants like leaves from flowers or trees. We think of algae as large mats of cells covering ponds and lakes, but they are made up of single-celled organisms. Each cell can exist independently. They are among the oldest of plant life on Earth, too.

Algae bloom, Lake Erie (USA), 2009 (Wikipedia)

As such, the chloroplasts in algae cells are different from those in flowering plants. Floral plant chloroplasts begin as a structure called a proplastid and then change as the plant ages from a seed to seedling to full-fledged plant. In fact, other types of plastids can come from the protoplastid and reside in different parts of the plant to produce flower colors (chromoplast), storage compartment in roots, seeds, tubers  (leucoplast), or developing leaves (etioplast, which stores material later changing to chlorophyll in chloroplasts). Gerontoplasts are old-age chloroplasts formed when plants reach the end of their life.

Image from Study.com

But chloroplasts from algae rarely change into other plastids. It might be this stability that allowed the Japanese team to succeed.

Sachihiro Matsunaga's research team first grew Cyanidioschyzon merolae in the lab, then broke open the cells chemically and physically (grinding) to release the chloroplasts. They were separated by centrifuging (spinning very fast). A heavy concentration of chloroplasts were placed in culture with hamster cells and gently shaken. These conditions probably causes a passive absorption of the chloroplasts into the cells. 

General isolation technique for chloroplasts and whole C. merolae cells (Aoki et al., 2024)

They confirmed that cells had taken up chloroplasts with fluorescent dyes and viewing under a microscope. See below from Matsunaga's study.

Next, they exposed the hamster "planimal" cells to light and measured the photosynthetic function. When they compared it to isolated chloroplasts (outside of the algae cells), they found that chloroplasts cultured with hamster cells for a day had more than half of the photosynthetic power and virtually the same after 2 days in culture. After four days, they lost the ability. The scale they used might seem small for efficiency, but regular chloroplasts in plant cells only get up to 0.6, simply because nature is not very efficient. But these results showed no loss of function after two days inside hamster cells.

 

Data modified from Aoki et al., 2024

In addition to providing medical science with cells that can produce oxygen which benefits others in the immediate vicinity, inserting chloroplasts into animal cells might have another benefit. The researchers reminded us that tissues grown in the lab could suffer from lack of oxygen because of the many layers of cells packed together. For example, it is possible to grow artificial organs, skin transplant sheets, and artificial meat in the lab.

Photo from Labiotech

Putting Humans in Stasis Is the Best Way of Getting Us to Mars

Link to article

Image from IEEE Spectrum

Human spaceflight to the moon took only 3 days one-way. A plan to send people to Mars would take much longer, 8-9 months under the best conditions where Earth and Mars are properly aligned. Sending anyone that far and back requires much more fuel, air, and food (including water) than a Moon mission, and the psychological stress of being so far away with so little to do until arrival (and return) can be a stressful experience. Keep in mind that all the astronauts would have to do is eat, sleep, and breathe, maybe do some exercising and take readings on the way. A minimum of 30 kg (66 pounds) of food and water is needed per astronaut per week, with critical systems recycling water and air along the way. But to conserve on supplies and minimize psychological stress (including boredom and loneliness), what if they could sleep most of the way, and how could that be done?

Bears hibernate, as do many other mammals. Can humans be forced to do that? A few scientific terms are important to consider. "Suspended animation" and "stasis" are not clear enough.

• Hibernation is a long condition, primarily in mammals, where metabolism and body temperature drop significantly. These changes allow survival through winter by conserving energy. Bears and hedgehogs hibernate; the only primate to do so is the fat-tailed dwarf lemur of Madagascar.
• Dormancy is the condition where a plant or animal has slowed down its bodily functions for a period of time, but it is not the same as hibernation (see table below). Some amphibians bury themselves during dry seasons where they remain dormant, for example. Seeds can be dormant until conditions are right for growth, and trees slow down metabolic activity in winter and reduce water content to avoid freezing damage. 
• A third term to remember is called torpor, which is an even shorter-term condition in animals with some metabolic changes less severe than in hibernation. It may last overnight, as in some hummingbirds, insects, and reptiles, or it may last a few weeks as with squirrels. The conditions that cause these body states and the length of time are all different (see below).

The Arctic ground squirrel hibernates 7-8 months of the year, because of the short summers in northern Canada, Alaska, and eastern Russia (Siberia). During hibernation, their normal body temperature of 37ºC (99ºF) can fall to below freezing -2.8ºC (27ºF). After a few weeks in torpor, they wake up and become active for a day to warm up again, then return to hibernation. 

Arctic ground squirrel (U.S. National Park Service)

In addition to the Arctic ground squirrel, whose body reaches temperatures below freezing, wood frogs in Alaska have been shown to survive even colder temperatures while they hibernate. Black bears hibernate for months at a time, but their body temperatures fall only slightly, from 38ºC (100ºF) to 31ºC (88ºF).

When we sleep, our metabolism naturally falls by around 15%, and our body temperatures also drop a few degrees. But we wake up hungry and need to get rid of built-up water as urine. To travel to Mars, it is estimated that a condition of torpor would be needed to reduce metabolism much more, about 75% (like bears). Here are some more specific reasons why this is necessary.

Since the 1980s, doctors have used targeted hypothermia (TH) to slow patients' metabolism with cold temperatures (32-34°C, 89-93°F) for a few hours for certain long surgeries or a few days (for certain brain trauma, for example). TH is done with cooling catheters, cooling blankets, IV with cold liquids, and applying ice around the body. 

Methods for inducing TH (Holzer, New England Journal of Medicine, 2010)

But patients get intravenous nutrients in the hospital, and their blood doesn't freeze. Blood flow is necessary to provide nutrients and remove waste. If blood freezes, that become a problem. The liquid part of blood is called plasma, and it is 92% water. Blood is made up of 55% plasma and 45% cells (which also contain about 60% water), so it is critical for an animal to control blood temperature during hibernation. Ground squirrels in North America regulate the content of their blood to avoid it freezing, especially around the heart, liver, and brain. Reawakening every 2 weeks simply causes enough physical activity to move blood around the other tissues. Because salty ions are taken out of the blood in torpor, the squirrels aren't thirsty.

Liquid and solid components of blood (BBC, The four components of the blood)

Muscle mass changes with the microgravity exposure. Researchers at the University of Marquette (Wisconsin) studied calf muscles of 5 astronauts and 4 cosmonauts on the International Space Station for 6 months in 2016. Some exercised on the treadmill for >200 minutes/week or less than 100 minutes/week. One example of a difference was in a calf muscle (soleus). Fibers deteriorated 3-8% in the longer running group but 27-29% in the shorter running group. Imagine if they were hibernating and not exercising at all!

Astronaut Steve Swanson using treadmill on the ISS. 

Bungee cords hold his body to the surface to counteract microgravity (NASA).

In 1990-1995, NASA joined forces with an American and Russian universities to study bone loss on 18 cosmonauts aboard the Russian Space Station Mir. The average bone loss rate was found to be 1-2% per month, even though the cosmonauts took part in two 1-1.5 hour sessions of treadmill or bicycle exercise for a total of 2-3 hours three days on and one day off. Again, hibernating individuals on their way to Mars will not exercise.

Science fiction stories have described putting humans into suspended animation, a form of artificial hibernation. The 1967 Star Trek episode "Space Seed" saw survivors in suspended animation chambers from 200 years before; the people were wrapped in a golden netted suit from neck to toes. The suit's purpose was not explained. A similar setup was used in Planet of the Apes (1968). Also in 1968, Arthur C. Clarke, had people in frozen storage chambers like a sarcophagus for an 18-month trip to Jupiter in 2001: A Space Odyssey. But in the 1984 sequel 2010: Odyssey Two, astronauts were on open beds and suited in a net-like uniform that presumably included sensors, food and waste tubing, and muscle massagers to prevent their bodies from deteriorating. People in the Alien movie series (beginning in 1979) wore minimal clothing in cold storage with sensor patches on their bodies. Greg Bear's 1985 novel Eon had people in frozen storage for 100 years or more; but their bodies were chemically treated before freezing to prevent cell damage in the freezing and thawing process, and nanotechnology helped repair any damage that might have occurred. But, just how feasible are those imaginative concepts now and in the near future?

With help from NASA, the aerospace company SpaceWorks Enterprises has been developing a module to keep humans in a torpor state on and off to simulate what squirrels do naturally. With the savings on food, air, and water, the SpaceWorks torpor module for 6 astronauts would be about 40 m³ in volume, compared to the original NASA design of 400 m³ which kept astronauts awake the whole trip. That's like the volume of 2 hollowed-out minivans (engine & seats included) vs. 20 of them.

Comparison of designs for astronaut habitats (NASA)

Depending on whether the torpor module has 4, 6, or 8 people housed inside, it's clear how much mass will be saved. The graph below shows the difference in consumables and machinery alone between the larger NASA module and the smaller SpaceWorks module.

Graph from NASA

How the bodies are arranged inside the module has not yet been settled (see 2 designs below right). But each person will need critical system monitoring. The theoretical care shown below represents two methods to feed the body either through the chest or thigh with Total Parenteral Nutrition (TPN): lipids, amino acids, dextrose, electrolytes, vitamins, and trace elements.

Images from NASA

Ways to regulate the temperature vary. A non-invasive method involves wrapping the body in a blanket, skull cap, or body pads that heats/cools, but they need to be changed every week. An invasive technique like the CoolGuard 3000R circulates a chilled/warmed saline solution through a catheter which is inserted into a large vein like a personal body radiator. Alternatively, RhinoChill is a small plastic tube placed in the nose where a spray of cooling mist evaporates near the brain, and the rest of the body is cooled as blood flows by. Finally, an entire warming/cooling platform like the KOALA System adjust the temperature of the entire enclosed habitat for each person.

From Schaffer et al., 2016

As shown earlier, laying out the astronauts can be done so that the torpor module can rotate to provide an artificial gravity. In addition to helping minimally with bone and muscle atrophy, gravity may also help the eyes, a serious concern for NASA. On Earth, gravity pulls blood and cerebrospinal fluids downward away from the head, but a lack of gravity redistributes the fluids evenly through the body. That means greater pressure inside the head and surrounding the back of the eyeball. It is enough to flatten the back of the eye and cause imperfect focusing on the retina. With 6 months or more in space, this can lead to serious vision problems.

Flattening of the eyeball after spaceflight (right) (Reilly et al., 2023)

What will be the problem on the brain itself if humans are placed in a cycle of torpor and waking? Ground squirrel EEG patterns are essentially flatline during torpor, so will that happen to people (and to what end)?  

A 13-stripe ground squirrel in torpor (Popular Science)

Is it safe or practical to put astronauts in a torpor state, to reawaken periodically, during an 8-month flight to and from Mars? Some sketches from SpaceWorks show possible robots to help make adjustments to the support systems attached to the astronauts. Alternatively, if a large crew were sent in several modules, a small crew of four might remain awake the whole time instead of using robots.

Two robots in the center of a hypothetical torpor module (NASA)

Brain damage is the number one concern for humans in any hibernation situation. Squirrel brain function as seen through EEG is nearly zero in the torpor state. But touching the animal or exposing it to a noise causes changes in the EEG, which suggests they are still aware of surroundings. Some even wake up in those experiments.

But to say "wake up" implies the animal or person is sleeping, and that's not technically true. Moreover, deep (REM) sleep is necessary for humans, and a lack of it causes problems: mood disorders, cognitive impairment, and difficulty learning new information. These are not issues that astronauts can afford to have so far from Earth! So, if humans can be put into torpor, they may likely not have REM because they are not really sleeping, and that's a concern.

Some studies have shown that as the brain cools down, specific areas shut off in a certain order. During torpor, the brain first reduces conscious awareness (neocortex), then arousal and sensory relay (reticular formation and thalamus), while keeping the hippocampus (converts short-term memories into long-term ones) active the longest. This could mean memory-related functions are preserved, even in deep torpor. More research is obviously needed, but this is a good start.

Mary Engle Pennington, the Ice Woman

The term "ice woman" often conjures up an image of a heartless female, but in the case of Mary Engle Pennington, nothing could be further from that. Born into a Quaker family on October 8, 1872, she grew up in Philadelphia, Pennsylvania. At 12, she became fascinated in medicinal chemistry from a library book, whereupon she asked local university professors to explain it to her. Despite being told to come back when she was older, she enrolled after high school in 1890 to the Towne Scientific School (formerly Department of Science) at the University of Pennsylvania to study biology, chemistry, and hygiene. The university did not grant bachelor's degrees to women, so she had to be satisfied with earning a certificate of proficiency instead.

Towne Building, University of Pennsylvania, 1906 (Penn Engineering)

Wanting to go further, she learned of an old college statute which gave the faculty power to grant certain degrees like a doctorate without the approval of the board of trustees (who had denied her bachelor's degree), and that's what she achieved in 1895. She studied under Edgar Fahs Smith, department chair who considered himself more of a historical chemist than a practical one. Smith had just completed advising Fanny R.M. Hitchcock, the first woman to get a doctorate in chemistry at that university (1894) and the first director of the women's graduate department in 1897. So, Mary's environment was now quite conducive to her later success. She probably gained more than chemistry training from Smith, since he was known to emphasize the humanistic side of science not a commercial approach to learning chemistry. This included moral aspects of their work, instead of just studying to be skilled technicians.

She stayed on for two more years as a doctoral fellow, then spent a year at Yale University working with Lafayette Mendel and Russell Henry Chittenden, the two founding fathers of the science of nutrition.

Photo from Yale University Library

Following that, she founded the Philadelphia Clinical Laboratory (1898-1906). She doubled as a bacteriologist with the Philadelphia Bureau of Health beginning in 1904, where she studied dairy samples for contamination. Pennington chose to teach farmers and ice cream salesmen about hygiene standards rather than just report the data. Basically, she just showed them what numbers of bacteria were in their samples under the microscope, and they immediately began boiling pots and ladles! Her standards for dairy quality became accepted nationwide.

In 1905, she added to her workload by accepting a position in the Department of Chemistry with the U.S. Department of Agriculture (USDA). One of her first projects was to investigate a claim that resturants had been served turkey meat that had been frozen for 10 years, but no customers had gotten sick. She showed that poultry could be kept frozen at -18ºC (0ºF) in good condition for one year. 

Her director Harvey Wiley (the "father of the FDA") there was so impressed with her work that he wanted her to lead the new division which became responsible for the 1906 Pure Food and Drug Act. To do so, she had to pass a Civil Service exam, not often given to women. She signed her application as "M.E. Pennington" to hide her gender and got the highest score on the test. When the Civil Service authorities told her director there was no precedent for hiring a woman, he countered by saying there wasn't a precendent against it, and she was hired.

Photo from Cowgirl Magazine

Two projects that she served on had immense importance to human health and earned her reputation as the "ice woman". First, she developed standards for the safe processing of chickens for human consumption. A simple but important finding was to keep fresh foods cold at a constant temperature. The 1906 Act didn't even refer to bacteria like Pasteur had shown half a century earlier in France. It just described avoiding "filthy, putrid,or decomposed" foods. Mary determined safe storage temperatures for many perishable food products like milk, eggs, and cheese. She also developed safer practices for handling raw poultry from slaughterhouse to market (Encyclopedia.com), as well as a new type of egg carton that reduced breakage during train shipping.

One example of her creativity is a patent she co-wrote in 1913 for a cooling rack for chickens and other meats. The rack could hold 180 chickens, ducks, or rabbits, 48-60 turkeys, or 72 geese in a design that maximized cooler space. Grading of the meat quality was easier and more accurate, too.

Pennington's patented cooling rack diagram and photo showing filled racks (USDA pat. 1,020,575)

Pennington's second achievement in refrigeration with the USDA concerned railroad refrigeration cars. Experimentation in shipping meats cross-country began in 1842. Just after the Civil War, cattle were shipped from Texas to processing centers around the country, but the animals lost weight or died in the transport. Railroad companies initially did not like the new cars for refrigeration because they were one third more expensive and might be used only on one-way trips. Some were filled at the ends with ice blocks, and the floors were insulated with flax or cattle hair. Allowing meat to directly make contact against ice resulted in discoloration and affected the taste. So, ventilation schemes ranged from simply opening the doors to open rooftop hatches to fans driven by the car’s axles. 

But the refrigerator was not a home appliance; people stocked cabinets called iceboxes with blocks of ice made artificially or harvested from frozen rivers and lakes. The first refrigerator was installed at a brewery in Brooklyn, New York, in 1870. The meatpacking industry followed with the first refrigerator introduced in Chicago in 1900, and it wasn't until 1913 that homes got their smaller models. Until such time as mechanical refrigerators were invented, ice sales were prominent. 

1867 refrigerated car with ice blocks on front and back 

Detroit, Michigan fish market owner William Davis devised a boxcar in 1868 with metal racks to hang the meat over a mixture of ice and salt. But the meat swayed and shifted the boxcar balance, sometimes causing derailments. Chicago meatpacking magnate Gustavus Swift then hired engineer Andrew Chase to make design improvements, and by 1881 he was sending 3,000 beef carcasses a week to Boston with almost 200 cars. Meats weren't the only food products shipped, and by the late 1890s, refrigerated shipping of all kinds of perishable foods including fruits and vegetables was done.

Rail car with ice compartment on top, 1877 (Wikipedia)

On October 3, 1908, Mary Pennington spoke to a Warehouseman’s Association in Washington, D. C. and explained the importance of cooling fruits immediately after being picked and not freezing them.  She showed that freezing food products caused chemical changes that significantly changed the composition of the product. Not only did she also show off a railroad refrigeration car there and explain its usefulness (something rather novel at the time), but she road with it to California where it was tested for use in hauling fruits from the orange and lemon groves and then shipped them to Florida.  Mary would travel with the car, check sensors, and carry out experiments along the way to improve their efficiency in transporting perishable foods. For example, she noted warm spots in the box cars and set standards for their construction to avoid such problems. Also, she found that the boxcar’s insulation was too thin and cracks could form in the exterior wall, exposing the scant insulation to the outside environment. She also discovered that meat should not touch and that boxes should have ventilation space between them.

Mary Pennington taking measurements on top of a box car, about 1910 (Ice Woman)

By 1930, her experiments revealed not only flaws in boxcar construction, but she also developed solutions to them.

• Boxcar walls should be made with several thicknesses of material
• Between each one should be insulating material of recognized efficiency.
• It should completely surround the boxcar, and especially protect joints, seams and corners.
• Wood or metal could be used for the outside of the box, but it should be attractive and easily cleaned.  
• The inside must be a material which moisture can't penetrate and which survives constant cleaning. 
• The inner wall should not have a finish to absorb odors or hold moisture, because it would permit mold growth.  
• Her examination found that only 3,000 out of 40,000 boxcars were certifiable.

She then turned her skills to households and food safety. In 1910, housewives in the U.S. refused to buy frozen foods, especially poultry because they thought they weren't fresh and because they caused illness. The reason was simple, though. After buying a frozen chicken, most of them put it in water or left it outside to thaw. Doing that contaminated the food. What they should have done was thaw it in the ice box. “No housewife can afford nowadays to remain in ignorance of what has happened to her chicken before she buys it,” she wrote in The Oregon Daily Journal on March 20, 1910.  Recognizing that women alone were not to blame, she ended the article as follows with a self-praising remark: “For some of its mischances, the housewife herself is responsible.  It is therefore fitting that, as women have done so much to afflict the modern supply of poultry, a woman [Pennington herself] should be the one to study out the remedies.”

Pennington in an undated photo (inventricity.com)

Six months after World War I started, Dr. Pennington attended the National Poultry, Butter and Egg Association conference in Chicago in 1917, where she spoke to encourage farmers to increase delivery of poultry, eggs, and fish. As you can see below, her words reflected not only the scientific statements of a scientists but also her compassion as a Quaker.

“A hungry man may rise to a moment of valor, but when a whole people are hungry, they become moral and physical weaklings.”

“The supply of beef is not enough to go around and the deficit must be made up with other food.”

“We must feed our men in the trenches and the men of our allies.  We must also feed the civilians of our own country and those of our allies.”

(Quotes from Wild Women of the West: Dr. Mary Pennington)

In 1919, Pennington resigned from the USDA and took a job director of American Balsa, which manufactured insulation used in refrigeration units. There, she created groundbreaking insulation techniques used on domestic refrigeration. A few years later, she started her own consulting company. The newly formed National Association of Ice Industries (NAII) contracted with her to be the head of their new Household Refrigeration Bureau. The NAII sought ways to increase ice sales in order to stock home iceboxes, but Pennington had other ideas to capitalize on her scientific credentials.

Her Bureau created pamphlets focused on the scientific basis of refrigerating foods and did not include any advertising of local ice dealers. This is important because the NAII had been formed in 1917 from 60 Chicago manufacturers and the publisher of the journal Ice and Refrigeration. She mailed from her New York City office only on request after home economics teachers, nutritionists, social workers, and other service professionals had seen them in circulars she sent out. Two notable titles were The Care of the Child's Food in the Home, Cold is the Absence of Heat, Journeys with Refrigerated Foods, and The Romance of Ice.

Pennington also contributed many articles to Ice and Refrigeration, such as the following:

• Standard Refrigerator Car Development (1919)
• Low Temperature in Transit (1924)
• The Construction of Household Refrigerators (1928)
• Fifty Years of Refrigeration In the Egg and Poultry Industry (1941)
• Refrigerated Warehousing of Tomorrow (1944)

She herself gave talks and a week-long Household Refrigeration School to teach ice company home service workers, mostly women, about the science behind spoiling of food. In 1927, she announced a "creed" for the Massachusetts Ice Dealers' Association; her Quaker roots caused her to write as one ideal of the creed: "There must be service, service, service, unselfish." Throughout the 1920s, she pushed ice manufacturers of the NAII to advertise for this service as a means to educate people (and as a side effect, it would help them to sell more ice). But by then, commercial refrigerators were on the market and had more advertising money to spend. When the stock market crashed in 1929, it was all over for the ice market, and Pennington stepped away from the Home Refrigeration Bureau.

Mary Pennington, 1940 (Wikipedia)

She maintained her consulting business until she died in 1952. By then, she had earned 5 patents and received the Notable Service Medal from President Herbert Hoover, as well as the Francis P. Garvan–John M. Olin Medal, which recognizes women chemists. Wikipedia sums up more accolades as follows: She was the first woman elected to the Poultry Historical Society Hall of Fame in 1959. She was inducted into the National Women's Hall of Fame in 2002, the American Society of Heating, Refrigerating and Air-Conditioning Engineers Hall of Fame in 2007, and the National Inventors Hall of Fame in 2018.

Dr. Mary Engle Pennington died on December 27, 1952, at the age of 80.