Category: Students Page 37 of 42

More on Human Evolution This Week

On April 8, 2013

Churchill displays the right hand of the adult female callled MH2. Her arm is complete from fingers to shoulder blade and collar bone.

One of the researchers displays the right hand of the adult female called MH2. Her arm is complete from fingers to shoulder blade and collar bone. Credit: University of Witwatersrand.

By Karl Leif Bates

Followers of the saga of human evolution are in for a treat later this week.

Duke’s Steven Churchill and an international team of colleagues will soon publish the second wave of papers from their analysis of two South African specimens called Australopithecus sediba.

We can’t tell you the details of what’s in the papers just yet because of the journal’s embargo policy, but trust us — it’s pretty cool!

UPDATE 4/12/2013 — The embargo has lifted, so details of the findings and a recorded interview with two of the scientists can be found on the Duke Research site. END UPDATE

At 2 p.m. on Thursday 4/11, you can tune into a Google+ Hangout to hear Churchill and Boston University’s Jeremy DeSilva describe the latest findings and ask your own questions.

Join the Hangout from 2 to 2:30 p.m. http://bit.ly/DukeGooglePlus

This latest round of analysis goes deeper into several areas of the anatomy of the two spectacularly complete A. sediba specimens and turns up some surprises.

~~This blog will also have a more complete report, going live right around that time, so come on back.~~

Two of Churchill’s former undergrad students, 2012 graduates Tawnee Sparling and Kelly Ostrofsky, are among the authors on the new papers. You can hear them talk about their work in this video.

The story of how scientists discovered the two specimens is pretty cool too — CBS Sixty Minutes did a segment on that a couple of years ago. View it here.

And here’s Churchill in a Sept., 2011 segment describing what the specimens are and what they might represent.

[youtube http://www.youtube.com/watch?v=pJOOo9C0dYE&version=3&hl=en_US&rel=0]

Australopithecus sediba – Steve Churchill Sept. 2011

Sharing food beyond the table

By sa160@duke.edu

On April 7, 2013

In Environment/Sustainability, Field Research, Students

By Nonie Arora

Duke Senior Emily McGinty is pioneering an effort to connect campus farms across the country. McGinty, a senior Baldwin Scholar and public policy major from Pittsburgh, Pennsylvania, has been passionate about food issues since high school. On campus, she is also actively engaged in Round Table Selective Living Group and Team Kenan, and is the managing editor for Rival magazine.

Emily braids and hangs garlic after harvest to cure it for longer-term use at the Duke Campus Farm. Credit: Emily McGinty

When she was organizing food-related discussions with Nicole Tocco, a former Duke masters student at the Nicholas School of the Environment and current employee of Bon Appetit Management Company, McGinty had a breakthrough about one of the fundamental problems in campus growing communities. “There was no platform for connecting, no hub for sharing best practices and ideas,” McGinty said. She wanted to create a centralized resource that would enable campus growers to communicate best practices in their investigative agricultural work.

McGinty’s underlying inspiration to create this centralized hub for campus farmers and growers comes from her experience helping develop the Duke Campus Farm. While Duke’s campus farm is only two and half years old, it is well established and strongly documents its own agricultural practices and research. Students work with professors and practitioners around the Triangle to investigate problems from crop science to building construction. The Duke Campus Farm community is also committed to intentional community building. McGinty explained, “It’s about developing reciprocal relationships. It’s very much a process – not just ‘making friends.’ But you can call it a professional site visit or hopping over to say hey to a neighbor. We’re all about building a strong community and learning from each other.”

She said she feels privileged to work in an area where sharing ideas has no drawbacks. “A fundamental piece of our desire to create a central hub is that we [campus farmers and gardeners] are in a remarkable situation where we have nothing to lose by sharing business plans. Your average corporation cannot share all their business plans and how they function the way they are, but we only benefit from ideas spreading,” McGinty said. “We can share everything from the structure of our board of advisors to parameters used for growing 500 feet of potatoes.”

Popular sungold tomatoes are packed for the Duke Campus Farm’s trip to market. Credit: Emily McGinty

Her team started by building an online platform where people across several college campuses could become members. They began with an online document, where members could upload their research practices in sustainable agriculture. Since then, they have gone through multiple iterations to find the best online home for the hub, which is still under development.

Over the last 6 months, she has conducted many site visits in North and South Carolina to pitch the idea and ask questions about how the hub would benefit others. One of McGinty’s major goals is to get students outside of the immediately interested food community to plug in. McGinty said she strongly believes that food work is interdisciplinary and undergraduate and graduate student research isn’t shared enough. She hopes that this website will reenergize original work produced by undergraduates relating to food issues.

Ultimately, McGinty hopes this open source philosophy will help campus farms across the country thrive by building communication networks and promoting evidence-based agriculture.

Chocolate's crisp crack comes from chemistry

By Ashley Yeager

On March 28, 2013

In Chemistry, Faculty, Lecture, Physics, Science Communication & Education, Students, Visualization

By Ashley Yeager

This is the final post in a four-part, monthly series that gives readers recipes to try in their kitchens and learn a little chemistry and physics along the way. Read the first post here and the second one here and the third one here.

This bunny must have been made from quality chocolate. His ears are already gone. Credit: Waponi, Flickr.

When you snap off and savor the ears of a chocolate bunny this Sunday, say a quick thanks to science.

“The essence of science is to make good chocolate,” said Patrick Charbonneau, a professor of chemistry and physics at Duke.

He explained that cocoa butter, one of the main ingredients in chocolate, can harden into six different types of crystals. All six types are made of the same molecules. But, at the microscopic level, the types have distinct molecular arrangements, which lead to differences in the crystals that form.

“The problem with chocolate is that only two of these types have good texture when eaten,” Charbonneau told students in the Chemistry and Physics of Cooking.

He teaches the freshman seminar with chef Justine de Valicourt and chemistry graduate students Mary Jane Simpson and Keely Glass.

During class, students looked at and tasted chocolate containing only the good-tasting crystal types and some that also contained the less favorable ones. The first had that signature sheen and snap of quality chocolate and melted evenly when left on the tongue. The latter pieces were dull, melted with the slightest touch and left a sandy texture on the tongue.

The demonstration showed that the different types of chocolate crystals melt at different temperatures. By carefully controlling the chocolate as it cools, chocolate-makers can create mixtures of only the favorable crystal types.

The process, called tempering, takes chocolate through a series of heating and cooling steps. The initial cooling step forms many of the chocolate crystal types, including the dull, unfavorable ones. Warming the mixture a little — to about 31°C (87°F) — melts the unfavorable crystals but not the best-tasting ones.

As the mixture cools again, the remaining, favorable crystals “seed” the chocolate so that good-tasting crystals form preferentially throughout, ensuring good chocolate structure and taste.

Students got a chance to test the science in lab later that evening, and judging by the number of mouths (and faces) covered with chocolate, it’s safe to say the science was successful.

If you’re looking to try it out — or save a poor bunny’s ears — here’s the recipe.

Tempering chocolate:

Materials:
1 small, microwave safe bowl
1 big bowl
1 spatula
2 scraper spatulas
1 chocolate mold
parchment paper
cooking thermometer

Ingredients:
250 g Dark Chocolate or 250 g Milk Chocolate (about 1 1/3 cups)

Filling:
60g white chocolate (about 1/4 cup)
60g yogurt (a little less than 1/4 cup)

Instructions:

1. Place milk or dark chocolate in the small bowl.
2. Heat the bowl in 30-second intervals in a microwave (stirring after each) until the chocolate is melted. Note: The milk chocolate should take about 1.5 minutes and the dark chocolate about 2 minutes to melt.
3. Once heated, pour half the liquid chocolate onto a clean marble or stone counter. The chocolate puddle should be the size of a medium pancake. (Note: If there is not stone or marble surface, another technique is to melt less chocolate and then add good tempered chocolate in it to lower the temperature.)
4. Spread the pancake portion out in ribbons using the scraper spatula. Bring the chocolate back together into a mound repeatedly for 5 minutes, until it starts to solidify.
5. Put the chocolate back in the original heating bowl. Adding the cooler chocolate will cool the rest of the liquid to the right temperature.
6. Mix the cold and hot chocolate.
7. Check the temperature of the chocolate. (Dark: 31-32°C/88-89.5°F; Milk: 29-30°C/84-86°F).
8. Dip the parchment paper in the mixture of the “hot” and “cold” chocolate. If it cools on the parchment paper and is uniform and shiny, then it’s ready.
9. Pour chocolate into mold.
10. To make stuffed chocolate candies, flip the mold to empty excess chocolate.
11. Turn it back, scrap the excess of chocolate off the surface. Let the thin layer of chocolate in the mold crystallize.
11. Melt white chocolate. Mix it with yogurt. Cool to room temperature.
12. Add filling to 2/3 of the mold cavities, and then pour more tempered chocolate on top.
13. Level the chocolate with a scraper and scrape off excess.
14. Let it rest for few minutes at 20°C (68°F) or put it in the fridge.
15. Pop candies from mold and enjoy.

Student Profile: Arnab Chatterjee

By sa160@duke.edu

On March 28, 2013

In Behavior/Psychology, Global Health, Medicine, Students

By Nonie Arora

Arnab Chatterjee, Duke Student. Credit: Chrislyn Choo

Freshman Arnab Chatterjee, Credit: Chrislyn Choo

Freshman Arnab Chatterjee spent three days in Abu Dhabi developing solutions to health care problems plaguing the Middle East. He travelled to the Global Issues Network conference, hosted by New York University in Abu Dhabi.

The conference pushes undergraduates to develop sustainable action plans to solve global problems on a regional level in just three days. It has a broad reach, from energy, to health, to waste management. The plans are intended as stepping-stones to bringing positive change to the region.

Chatterjee’s small group focused on mental health, which is often disregarded as a legitimate health concern in the Middle East.

“The ruling bodies of the UAE don’t acknowledge that mental health issues are a real problem, so it often gets swept under the rug,” Chatterjee said.

The group initially attempted to avoid a direct discussion of mental health by asking patients about irregularities in their sleeping and eating patterns, which can be early indicators of mental health issues.

Chatterjee’s team discovered that diabetes was one of the top contributors to the UAE’s mortality rate, and an issue that the government was very much invested in addressing. Multiple studies have suggested a correlation between an increase in the rate of depression among diabetes patients, and vice versa. Other work has shown that the mortality rates among patients with diabetes and depression are significantly higher than those with just diabetes, Chatterjee said. But in this region, seeking help for a mental illness is highly stigmatized. Addressing depression by targeting diabetic populations and their families alleviated this stigma somewhat.

Near the end of the conference, his team suggested that a clinical research study be conducted by New York University’s public health institute in the region to address whether patient-family support specialists could be helpful in improving patient outcomes. They planned to screen for depression, but without describing the behavior by name. “People can be offended even by doctors asking questions that imply a patient has depression. It’s a delicate balance between being tactful but remaining effective,” Chatterjee said.

Chatterjee and his team presented their plan to health care providers from Cleveland Clinic’s medical center in Abu Dhabi, government officials, and the press in Abu Dhabi. He said it was well received by most, but that the government officials remarked that they would have preferred even less emphasis on mental health issues.

Beyond this specific project, Chatterjee said that attending the conference gave him a great opportunity to build a global network with other undergraduates with diverse interests. He is interested in medicine and research, works as a research assistant in the Nicolelis Primate Laboratory, and will be working as a Howard Hughes Research fellow this summer.

Summer camp inspires allergy research

By Ashley Mooney

On March 5, 2013

In Biology, Medicine, Students

By Ashley Mooney

Courtesy of Nicole Leung.

For some undergraduates, research ideas stem from summer camp.

Junior Nicole Leung, a biology major concentrating on pharmacology, is doing an independent study on allergies and pediatric immunology. She works in Dr. Wesley Burks’ lab at the University of North Carolina in Chapel Hill and explained that her interest in allergies first started when she was a volunteer at a summer camp.

“I was taking care of a little boy who was allergic to so many foods and he had to carry an epi-pen around with him all the time,” she said. “It was my first exposure to such a serious problem with allergies.”

“It was really hard for me to see a boy who was so close to being normal be completely abnormal during camp,” she said, adding that because of the boy’s severe allergies, he was very shy and had a hard time making friends.

Leung saw the challenge of severe allergies again in college when a gluten allergy started to affect her freshman-year roommate.

Now, Leung is trying to understand whether people can develop a long-term tolerance to food allergies, even though there is currently no cure for allergic diseases. The lab is also developing immune-system therapies to sensitize patients to allergens and see how long they can withstand the allergic effects.

“Very little is known about allergies, but they tell a lot about our immune system,” she said, adding that “as the human population grows, I think that allergies are going to be a major concern in the future, so this field has great potential.”

In Leung’s previous research, she compared several allergy tests to find which best predicts the severity of allergic reactions. Most common allergy tests, like the skin-prick test and the blood-based ImmunoCAP test, do not determine how severely people may be allergic to certain substances.

Courtesy of Nicole Leung.

“They only will tell you that you’re allergic but you might not have a reaction to it,” she said.

Using a statistical analysis, Leung found that the basophil activation test has a much higher correlation to severity than the skin-prick or ImmunoCAP tests.

“With the basophil activation test, we mix allergens in blood and try to see whether a certain allergen will cause basophils to degranulate and release histamines, which is what triggers the allergy symptoms,” she said. “Because these activated basophils expose CD63 molecules on their surface, we can determine the percentage activated and use cutoff points to identify whether the person is allergic.”

She added that the test only requires a small amount of blood and is a relatively quick procedure. But there are still questions of how it can be applied to clinical practice.

For Leung, the hardest aspect of research is digging through background information to find out how to move her project forward.

“None of the articles point you to a clear answer, and that is the most challenging part of research. But it is also the most exciting part because you get to test your own hypotheses,” she said.

Besides her allergy research, Leung also works in a neuroeconomics lab that looks at risky decision-making in gambling. The lab uses eye trackers to measure how much a test subject’s eyes dilate and how often they shift their eyes between two choices—one risky option, and one safer one.

Although Leung said she has a more direct role in the design and implementation of her allergy research, she said she enjoys meeting and interacting with the families who participate the neuroeconomics study.

Tracking the cell transitions that cause cancer

By Ashley Mooney

On March 4, 2013

In Biology, Cancer, Students

By Ashley Mooney

Courtesy of Tristan Bepler.

Researchers think that for cancer to develop, damaged cells have to undergo certain transitions that cause them to spread, or metastasize.

Junior Tristan Bepler, a biology and computer science major, is testing this hypothesis, studying two types of cell transitions scientists have linked to the spread of cancer. He works in the lab of Mariano Garcia-Blanco, professor of molecular genetics and microbiology, and looks at the mesenchymal-to-epithelial transition, or MET, and the epithelial-to-mesenchymal transition, or EMT. Mesenchymal cells are more motile, while epithelial cells tend to be fixed in rows.

The hypothesis is that when epithelial cells form tumors, like in colon, prostate or breast cancer, the cells at the edge of the tumor have to turn to mesenchymal cells for the cancer metastasize. Then, “the mesenchymal cells can leave the tumor, get into the blood stream and spread around your body,” Bepler said.

In order for cells to latch onto cells in new locations, they have to transition back to epithelial cells through MET. Bepler’s research focuses on whether MET or EMT are necessary for metastasis.

Most of Bepler’s daily activities involve culturing cells and handling the rats the lab uses in for the research.

The scientists grow tumors in the rats, they inject them under the skin on their flank. “When we’re growing tumors, we have to measure the size of the tumors and weigh the rats to make sure they’re not gaining too much weight,” Bepler said. “Once the tumors get too large, we have to sacrifice the rats and dissect them. We collect their tumors and their lungs, then we can section them and look at fluorescence, which is how we track MET and EMT.”

Although the project is in the basic sciences, it has the potential for clinical use. If EMT is necessary for diseased cells to spread, drugs that block the transition may be effective in treating certain types of cancer. Clinical application is still a long way down the road, though, Bepler said.

Choosing to study metastasis, rather than viruses, which the lab also investigates, “really wasn’t driven by a desire to study cancer at the time,” Bepler said. “I really didn’t know anything, so I decided I would do the cancer side.”

A Durham, N.C. native, Bepler began his lab work the summer before his freshman year. “When you first start working in the lab, you basically work as a lab tech. Your mentor says, ‘do this experiment,’ and you do the experiment,” he said. “It’s sometimes hard to feel like what you’re doing is important or like you’re really involved in the project because you’re just working as a lab tech, you’re not intellectually involved.”

“The key is to get into the biology of what’s going on or think about the experiments and then it becomes a lot more interesting, because after a while you come up with good ideas for experiments, and you become a little more independent and can do your own experiments,” he said.

Bepler added that he prefers working with rats, as opposed to mice, because they are more friendly and do not bite as often.

Thinking Beyond the Grave at Duke-UNC Bioethics Symposium

By sa160@duke.edu

On February 26, 2013

In Medicine, Science Communication & Education, Students

By Nonie Arora

Duke student Meredith Rahman is intrigued by how we justify treatment of the dead for the sake of science. She asked her audience at the Duke-UNC Bioethics Symposium: How can we interact with human remains in an ethical way?

Duke Student Meredith Rahman Presents at Duke-UNC Bioethics Symposium. Credit: Nonie Arora

Rahman began the discussion by explaining how bodies are obtained for use after death. “Historically, there was great fear about grave robbings to further science,” she says, “but that has since calmed down.” Now, many bodies are obtained through donation, and we legitimize the use of bodies through prior consent when the subjects are still alive. In the 1980s however, the Body Farm in Knoxville, TN took unclaimed bodies from medical examiner’s offices to study decomposition, she added.

Rahman discussed what can happen when we can no longer speak for ourselves. There can be tension between the wishes of the deceased and wishes of the family members, and it can be hard to give a voice to those who have already passed away. This is similar to situations in which family members may override do not resuscitate (DNR) orders, Rahman clarified.

There’s a further issue of consent even when a person has signed a donor card to say that they want to donate their body to science: they don’t always know how their body will be used. “It could be an undergraduate student, such as myself, going into the lab and learning basic anatomy, or it could be an MD practicing a specific surgical skill. But when you consent to donate your body to science, you no longer have a say over what happens,” she said.

A plastinated human body exhibited at the Body Worlds show, Museum of Natural History, San Diego, 2009. Credit: Wikicommons. Photograph by Patty Mooney, Crystal Pyramid Productions, San Diego, California.

Some exhibits transform human remains for science education, such as the Body Worlds exhibit, according to Rahman. Body Worlds relies on a technique called plastination, which essentially turns human soft tissue into plastic. The result is a body that is about twenty percent human materials. She said that while these bodies can be effective teaching tools, there are ethical considerations, especially when commercial interests are involved and the primary purpose is public viewing rather than scientific development. The audience was shocked to hear that “slices of human” are available for purchase.

Rahman’s presentation was part of the Duke-UNC Bioethics Symposium, Ethical Frontiers in Research, a student-run conference developed by the Duke Undergraduate Bioethics Society (DUBS) and Carolina Bioethics Scholars (CUBS). This year, the organizations have received funding from the Kenan-Biddle Partnership grant as well as the Kenan Institute for Ethics and the Trent Center for Bioethics, Humanities & History of Medicine. As part of the Kenan-Biddle partnership, they are hosting an ongoing series of dinner discussions on bioethical topics. The next event will be hosted by UNC on Feb. 28; Dr. Steven Gray will discuss how gene therapy clashes with traditional pharmaceutical business models.

As an executive board member for DUBS, I am excited to continue our collaboration with UNC students. Although basketball rivalries may pull us apart, last weekend we found that lively ethical conversations can bring us together.

Diffusion a la Chocolate Lava Cake

By Ashley Yeager

On February 21, 2013

In Chemistry, Faculty, Physics, Science Communication & Education, Students, Visualization

By Ashley Yeager

Note: This is the second post in a four-part, monthly series that will give readers recipes to try in their kitchen and learn a little chemistry and physics along the way. Read the first post here.

Making chocolate lava cakes demonstrates the diffusion of heat. Credit: Ashley Yeager, Duke.

Between bites of hot lava cake and vanilla ice cream, freshmen taking Chemistry and Physics of Cooking talk about diffusion. Their conversation isn’t so esoteric that an outsider wouldn’t understand.

Instead, it’s a simple chat about how long to cook a cake based on how heat moves.

Understanding diffusion is a way to make sense of cooking times, says chemistry and physics professor Patrick Charbonneau, who is leading the class along with chef Justine de Valicourt.

Diffusion of matter is how particles in a liquid, gas or solid intermingle and move from a region of higher concentration to one of lower concentration.

Heat diffusion describes how hot particles warm up cooler particles around them, which allows the inside of a dish to cook, even though only the outside is heated.

Before turning his students loose in a kitchen in Smith Warehouse to eat a product of this process, Charbonneau and his teaching fellows had the group work through the equations that describe diffusion.

“Solving the diffusion equations of heat gives you a first estimate of how long to bake a cake or cook a turkey,” Charbonneau says. The cooking time for lava cake is especially critical in order to get the outside it to bake, while the inside remains gooey, de Valicourt adds.

In class, the students calculated that to make a muffin-sized lava cake with ingredients at room temperature in an oven at 400°F (204°C) would take about 10 minutes. In the lab, they found that the calculation was fairly accurate, but for a more exact estimate of cooking time, they needed to factor in the temperature of melted chocolate chips in their recipe.

“Still, with the cooking time being not so mysterious, it’s one fewer thing left to chance,” Charbonneau says, adding, “then you can be more creative with the recipe in other ways.”

He and de Valicourt, who have partnered with the Alicia Foundation to offer the Chemistry and Physics of Cooking class, have provided the following recipe for experimenting with diffusion and hot lava cake.

Hot Lava Cake —

Ingredients:
60g (1/3 c) dark chocolate chips
60 g (1/2 stick) butter
60 g (1/4 c) sugar
3 eggs (or 2 egg and 45mL (3tbs) coconut milk)
30 g (1/4 c) flour
small pinch salt
Non-stick cooking spray

Materials:
1 bowl (bain-marie)*
4 ramekin dishes or 1 muffin tin
2 medium bowls
1 scale (if weighing ingredients)
1 sieve
1 cooking thermometer (optional)

* You can make a bain-marie by placing a bowl over a saucepan of simmering water.

Instructions:

1. Preheat the oven to 400°F/204°C.
2. Melt chocolate and butter on bain-marie. Stir. Do not boil the water or the chocolate could burn.
3. Combine eggs and sugar (and coconut milk) in a medium bowl and whisk until bubbly.
4. Combine flour and salt in another bowl and pass it through the sieve.
5. With one person whisking and another pouring, slowly add the chocolate mixture to the egg mixture.
6. Add the flour and salt to the wet ingredients and whisk well.
7. Spray ramekins or muffin tin with non-stick cooking spray.
8. Fill the ramekins or muffin tin a little more than halfway full.
9. Place the ramekins or tin in the oven on the middle rack.
10. Bake until the cakes start growing. The interior of the lava cake should be around 158-176°F/70-80°C and the outside around 203-212°F/95-100°C – ie until the edges of the cake are set, but the center is still a liquid – about 7 to 10 minutes (less for smaller cakes).

Blasting away glioblastomas

By Ashley Mooney

On February 21, 2013

In Biology, Cancer, Medicine, Neuroscience, Students

By Ashley Mooney

The purple area of this brain is a glioblastoma tumor.

Some undergraduates get to see the fruits of their lab labor early in their careers.

Junior Anirudh Saraswathula, a biology major and neuroscience minor, has been doing research at Duke since his first week on campus.

He started as a work-study student in professor of cell biology Blanche Capel’s lab, but said the basic sciences were not his true passion. Now, Saraswathula works on translating basic research with the Duke Brain Tumor Immunotherapy Program.

“A lot of what I do in the lab involves looking at protocols that are used in basic science research and trying to apply them to what we’re doing here,” he said. “So a lot of it is going to be culturing cells from patients, and then doing a variety of tests depending on what it is that I want to do.”

He is currently studying immune-system therapy for glioblastoma, a type of malignant brain tumor. By reprogramming a patient’s T-cells, researchers can direct the immune system to fight glioblastoma. Although Saraswathula was not involved in developing the treatment, he is working to evaluate the treatment’s mechanism and its long-term effects on the immune system.

“One of the reasons that brain tumors are so devastating (with treatment they can extend survival to about 18 months) is that they’re just so recurrent,” he said. “These types of tumors also change who you are as a person because of where they happen.”

Saraswathula’s day-to-day work involves culturing tissue, using flow cytometry — a technique used to sort cells, detect biomarkers and engineer proteins — and PCR, which copies DNA.

Saraswathula is also studying the quality of T-cell responses to different clinical trials and understanding whether certain types of B-cells are repressing the function of the tumor vaccine.

“Those projects are focused on future trials. How can we improve, how can we modify these therapies to better improve the immune system’s response in order to fight these tumors,” he said.

Although he began his research just for the experience of doing it, Saraswathula said that applicability is now what is most important to him.

“If I discover some obscure gene in stem cells, there’s not going to be any real application there for maybe 30 years,” he said. “With my current research, if I find something, [in] the next trial a few years from now, there will be a patient getting the drug, and I would have had a contribution to that.”

Cooking up chemistry with candy

By Ashley Yeager

On January 23, 2013

In Chemistry, Physics, Science Communication & Education, Students

By Ashley Yeager

Note: This is the first in a four-part, monthly series that will give readers recipes that they can try in their kitchen and also learn a little chemistry and physics along the way.

Making sucre à la crème (left) and soft toffee (right) illustrates the fundamental principles of changing a liquid to a solid. Credit: Ashley Yeager, Duke.

A dozen freshmen pull on pieces of fresh, soft toffee, popping the candy into their mouths and licking it from their teeth as chef Justine de Valicourt talks about making the treats in a tiny kitchen on the second floor of Smith Warehouse.

Eating toffee and other sweets doesn’t usually spark a discussion about chemistry. But, as the students learn, the core of the eating experience is entirely about chemistry and some physics too, says professor Patrick Charbonneau.

He is leading a freshman seminar, called the Chemistry and Physics of Cooking, and in this particular class, he, de Valicourt and a team of teaching assistants work with the students to explore phase transitions – such as the change of liquid water to ice – by making two traditional Québécois desserts, sucre à la crème and soft toffee.

Both desserts have the same ingredients — maple syrup, butter and cooking cream. But, the experience of eating them is entirely different. One, the toffee, is stretchy, chewy and sticky, while the other, the sucre à la crème, is more crumbly and smooth.

The way the sugar molecules in solution cool down into a solid structure is what determines the final texture of a candy or chocolate, Charbonneau says.

During the lab, the students cool one mixture of syrup, butter and cream quickly and then whisk it. The stirring motion forces the sugar molecules to bump into each other, creating seeds of crystallization, which continue to grow and eventually clump together to give the sucre à la crème its solid, crumbly texture.

The students mix and heat the ingredients, then let them cool slowly, leaving the candy to set for at least three hours. Not whisked or stirred, it solidifies without forming too many large crystals, giving it a glassier appearance and a stickier, chewy texture, a signature feature of toffee.

Making these candies is pretty basic, easy enough that anyone could try it in a home kitchen, Charbonneau says, adding that he and de Valicourt have provided the recipes as a way to reach beyond the classroom and give more than just their students an introduction to cooking and, of course, the chemistry behind it too.

Sucre à la crème —

Ingredients:
1 can of maple syrup (540mL)
45 g (3 tbsp.) of butter (plus some to grease the mold)
250 ml (1 cup) of cooking cream 35%

Materials:
1 medium saucepan
1 candy thermometer
1 wooden spoon
1 square mold
1 whisk
1 bucket of cold water

Instructions:

1. Put all ingredients in the saucepan. Stir.
2. Heat on the stove to 118°C (244°F) – 120°C (248°F). Be careful not to touch the bottom of the pan with the thermometer, which will give an incorrect reading.
3. Put the saucepan in the bucket of cold water and let the mixture cool down to 55°C (131°F) – 60°C (140°F) in the center. Do not stir the mixture.
4. Once cooled in the water, whisk the mixture to make a creamy pale paste. Pour in the mold and cut it before it gets too hard.
5. Let it rest 30 min in the fridge.

Soft toffee —

Ingredients:
1 can of maple syrup (540mL)
45 g (3 tbsp.) of butter (plus some to grease the mold)
250 ml of cooking cream 35%

Materials:
1 medium saucepan
1 candy thermometer
1 wooden spoon
1 square mold

Instructions:
1. Put all ingredients in the saucepan. Stir.
2. Heat on the stove to 118°C (244°F) – 120°C (248°F). Be careful not to touch the bottom of the pan with the thermometer, which will give an incorrect reading.
3. Pour into the greased mold, let it cool down slowly, without disturbing it for 3-8 hours.