Category: Chemistry Page 6 of 7

Not Your Mama's Chem Lab

On November 21, 2013

In Chemistry, Environment/Sustainability, Students

By Erin Weeks

Deep in the basement of French Family Science Center, eleven chemistry 210 students are completing one of their last labs of the semester. Bob Marley plays from a speaker in the ceiling, and the students are huddled around their computer screens, watching lines plot on a rainbow-colored graph.

It looks like an average lab session—but believe it or not, the students are engaged in cutting-edge energy science.

The students worked with cobaloxomine, shown here, and a variety of colored cobalt complexes in the lab.

The students worked with cobaloxime, shown here, and a variety of colored cobalt complexes in the lab (Courtesy Wikimedia).

While undergraduates can still expect to learn the techniques and concepts familiar to introductory chemistry classes everywhere, Duke’s chemistry department recently revamped the laboratory portion of CHEM 210, Modern Applications of Chemical Principles, with the help of a mini grant from Trinity College of Arts and Sciences. Now students learn through the lens of one of modern chemistry’s biggest challenges: energy.

Associate chair and professor Kathy Franz says the department wanted students to be able to tie their laboratory work to real-world chemistry problems—like converting sunlight into usable fuel.

“Researchers around the world are working on each step needed to close the loop of artificial photosynthesis and link it to fuel cell use,” the lab manual reads. “There are still basic chemical questions yet to be answered about that deceptively simple-looking equation” that describes photosynthesis.

Some of those top researchers, including Dan Nocera and his lab at Harvard, use cobalt-based catalysts in their efforts to streamline artificial photosynthesis—and now, so do chemistry students at Duke. The lab today tasks students with building their very own simple cobalt catalysts to perform half of the artificial photosynthesis equation.

Just like professional chemists, the students face technical frustrations and rewards. Lab manager Deborah McCarthy rushes around the room with a sharp eye, correcting missteps. One group forgot to add eosin Y, a reddish dye, to their solution. Another group fails to dissolve their cobalt complex in acetone, and yet another skimped on the NAD+. But on second and third tries, when everything goes right, the students’ rainbow graphs spike perfectly, signaling their success—they’ve produced NADH, a form of stored energy used in living cells.

Spherical Cows Help Turn Proteins to Crystals

By Ashley Yeager

On November 13, 2013

In Biology, Chemistry, Engineering, Mathematics

By Ashley Yeager

"Physicists want to do what to me?" (Courtesy SXC.HU)

The spherical cow is a long-standing physics joke, funny to us, but maybe not to her. (Courtesy Marijn van Braak)

It may be impossible to tip a spherical cow. But by searing one on the computer, scientists may have found the best recipe yet for transforming proteins into crystals.

Crystallizing a protein is not as simple as throwing it in the freezer and letting it chill, the way liquid water turns to ice. “We would like to know what is going on at that fundamental level when we crystallize a protein. But we don’t,” said Patrick Charbonneau, an assistant professor of chemistry, physics and computational biology at Duke.

But by looking at each protein as if it were a spherical cow with sticky patches, Charbonneau said scientists could learn more about the standard set of interactions that transform proteins from a liquid solution into crystals.

The idea of a spherical cow is not new. It comes from an old physics joke where a farmer calls the local university for advice on getting his cows to produce more milk. The university sends a physicist who looks at the barn, the cows and their production and says, “First, assume the cows are spherical and in a vacuum . . . ”

“Physicists idealize everything to the extreme, which could be why their most recent attempts to explain protein crystallization don’t quite work,” Charbonneau said.

Scientists want to know the fundamentals of protein crystallization because proteins are essential for living creatures to survive. Proteins come in many different shapes and have a variety of functions, and their structures explain how they interact with other molecules in the human body — information that often leads to more targeted medications.

To study protein shape, scientists precipitate them from liquid solutions into crystals, which is how DNA’s double helix structure was revealed. Physicists have also tried to model protein shape through computer simulations. In Charbonneau’s new model, he combines physicists’ past simulations based on the spherical cow model with the best protein-crystal-making insights from structural biology.

The new hybrid is what Charbonneau calls the patchy cow model. To develop it, he and his students digitally recreated the structure of the protein rubredoxin as a spherical cow, making it resemble a basic blob-like molecule. The team then applied patchy areas, which acted like the atomic interactions shaping the structure of a protein.

“We found the model actually works, giving us a patchy picture that does predict some of the crystal structure of proteins,” Charbonneau said. It is the first time a simulated model of protein crystallization has matched well with the temperature, salinity and other crystal-forming conditions structural biologists observe in the lab. And “it’s the first time that we can draw clear physical insights from how the model compares with experiments,” he added.

A single protein crystal of lysozyme (Courtesy Wikimedia)

Charbonneau first began working on the protein crystallization problem as a post-doc at Amolf in the Netherlands. When he came to Duke in 2008, he met David and Jane Richardson — leaders in the field of protein crystallization and structural biology. From them, Charbonneau began to realize that physicists and structural biologists don’t know each other’s work. “We don’t cite each other, and we don’t trust each others’ descriptions of protein crystallization,” he said. The goal of his work, he explained, is to convince the disciplines to begin talking to each other.

The biggest problem for both camps is that they know the atomic and molecular interactions that should be involved in crystallizing a protein, but they “cannot make sense of what is going on. It’s figuring out the mechanism, the physical process, that is frustrating,” Charbonneau said. His new model tries to paint the physicists’ spherical cows from the perspective of the observations the Richardsons and others have already made in the crystallography community.

Charbonneau anticipates that the patchy spherical cow model might help structural biologists predict what conditions they need to crystallize any protein of their choice. But first, he said, the team needs to put their model to another test, simulating crystallization in more complex proteins, such as physicists’ favorite, lysozyme.

Citation: “Characterizing protein crystal contacts and their role in crystallization: rubredoxin as a case study,” Diana Fusco, Jeffrey Headd, Alfonso De Simone, Jun Wang, and Patrick Charbonneau. Soft Matter, November 8, 2013. 10.1039/C3SM52175C.

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.

Meat Glue — True to its Name

By Ashley Yeager

On March 8, 2013

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

By Ashley Yeager

This is the third 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.

Students grab chunks of a fish “checkerboard” made from salmon and flounder cubes. Credit: Ashley Yeager, Duke.

Braided steak and checkerboard fish may sound exotic. But, freshmen in the Chemistry and Physics of Cooking had no fear fingering the meaty masterpieces into their mouths.

The students made this food art – one literally a braid of three steak strips and the other a combination of salmon and flounder cubes – using a molecule called transglutaminase, also known as meat glue.

In 2012, the media roasted meat glue’s reputation, branding it a dirty little secret meat vendors use to stick together cheap cuts of beef, lamb, chicken or fish and then sell as premium cuts.

“In this class, we’re not using the molecule to be dishonest. We’re using it to be creative,” said physical chemist Patrick Charbonneau, who leads the freshman seminar along with chef Justine de Valicourt and teaching fellows Mary Jane Simpson and Keely Glass.

During a lecture, Glass explained how meat glue — an enzyme that speeds chemical reactions — forms covalent bonds between some of the amino acids that make up the proteins in meat and meat substitutes. With just a sprinkle of the enzyme, which comes in a powder form, chefs can then weave together beef cuts, form game-piece patterns from fish or even bind beans, seeds and other ingredients into a veggie burger that doesn’t crumble after the first bite.

“Meat glue is like a lot of modern ingredients. It comes from industry, and you can use it to make industrial food,” like chicken nuggets, de Valicourt said. “But when you master it, you can use it in a very creative and delicious way.”

Chefs often use the fundamentals of chemistry and physics to shape other foods, such as chocolate. “We’re doing the same to shape meat,” Charbonneau said, explaining that the students used transglutaminase in lab to create beautiful, and delicious, combinations of meat far superior to chicken nuggets and other industrial food typically made with the enzyme.

To make your own meat masterpieces, try the following recipe:

Materials:

1 long sheet of plastic wrap OR a bowl
1 cutting board
1 knife
2 latex gloves for each person
1 mask for each person
1 meat grinder (optional)
1-3 gallon-sized Ziploc bags
1 scale

Ingredients:

1 portion fish, chicken, beef OR vegetarian protein (ie black beans and sunflower seeds)
10 g meat glue powder (available online here)

Instructions:

Gluing meat chucks together –

1. Choose meats
2. Place meat on plastic wrap
3. Choose meat pattern – braid or stack
4. Season meat with salt and pepper
5. Put on gloves and mask and measure 10 g of meat glue using the scale
6. Sprinkle meat glue on sides of meat you want to connect
7. Fold meat into desired pattern
8. Place meat in Ziploc bag
9. Refrigerate for 6 hours
10. Cook meat as you would any other time

Making meat patties –

1. Choose meats, grind in meat grinder, and mix in a bowl (Or, buy ground meat and mix)
2. Season meat with salt and pepper
3. Put on gloves and mask, then measure 10 g of meat glue using the scale
4. Add meat glue to meat and knead until fully mixed
5. Separate into two portions (or more for patties) and seal each in a Ziploc bag
6. Roll with rolling pin, if desired
7. Refrigerate for 6 hours
8. Cook meat as you would any other time

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).

Designing Microbial "Factories" Rationally

By Pranali Dalvi

On January 29, 2013

In Chemistry, Environment/Sustainability, Genetics/Genomics, Lecture

By Pranali Dalvi

Using microbes to manufacture chemicals is starting to be cheaper and greener than traditional chemistry. And their feedstock is sugar, not oil.

Source: 2010 Agricultural Biotechnology International Conference

On Friday, Dr. Michael Lynch spoke to an engaged audience about how microbes have ushered in a new era in metabolic and genetic engineering. Lynch is the co-founder and CSO of OPX Biotechnologies, a Colorado-based company that makes bio-based chemicals and fuels from microbes. OPXBIO microbes produce fatty acids from hydrogen and carbon dioxide. In turn, the fatty acids are used to make cleaners, detergents, jet fuel, and diesel.

Lynch said it’s easier to understand the genetic circuits and enzymatic pathways of microbes, thanks to much cheaper DNA sequencing. What we still lack though, is an understanding of how to rationally design complex biological systems – likely because we fail to recognize the interplay among an organism’s genotype, phenotype, and environment.

It’s a complex set of factors that go into making phenotypic traits such as color, size, or shape.

“In an industrial setting [phenotypes] are equivalent to metabolism or higher production of the product of interest,” Lynch said. “In a clinical setting, [phenotypes] could be virulence or pathogenesis.”

One approach to understanding how phenotypes are controlled has been through functional genomics.

Let’s say we take a population of wildtype microorganisms and introduce genetic modifications in a controlled way. Next, we selectively screen for the phenotype of interest and compare the sequence of this phenotype to the wildtype to pinpoint the genetic mutations that made the difference.

Comparing phenotypes one at a time is inefficient, though. Lynch wanted to find a way to speed up this process.

“We wanted a process or technology or toolkit that evaluates all of your genes in parallel in a single experiment for the phenotype of interest,” Lynch explained.

Lynch found his inspiration in microbial biofilms, extracellular polysaccharide matrices that grow quickly.

OPXBIO’s Efficiency Directed Genome Engineering (EDGE) technology platform, Source: opxbio.com

Lynch’s studies revealed that microbial cultures grown in enriched media made biofilms, while those in minimal media did not. In a process known as destructional mutagenesis, Lynch and his colleagues then knocked out biofilm-making genes to identify what genes cause the biofilm phenotype in enriched medium but prevent it in minimal medium.

Lynch saw the individual microbial systems as factories that he can genetically modify to produce chemical compounds in biofilms – specifically, 3-hydroxypropionic acid – that can be chemically converted to commercially relevant compounds such as acrylic.

Scientists at OPXBIO have cracked the code for making acrylic from sugar. They give sugar feedstocks to genetically modified bacteria, whose enzymes convert the sugar into acrylic molecules. Acrylic has broad commercial applications in paints, adhesives, diapers, detergents, and even fuel – a $10 billion global market.

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.

What To Expect When You're Expecting the Nobel Prize

By Karl Bates

On November 27, 2012

In Chemistry, Faculty, Lecture

By Karl Leif Bates

Photo Illustration by Jonathan Lee, Duke News

Duke’s soon-to-be Nobel Laureate in Chemistry, Robert Lefkowitz, is off to Sweden next week to pick up his prize and to shake King Carl Gustav’s hand — probably more than once.

But first, he has to visit President Obama at the White House, say a few words at the Swedish embassy, and do about a half-million other photo ops.

“It has been even more intense than I expected,” Lefkowitz said in a hurried conversation on Tuesday.

His Nov. 29 visit to DC will be “an amazingly intense day,” starting with a symposium and Q&A session at the Swedish embassy, followed by a 45-minute visit with the President and other American laureates in the Oval Office, then a reception at Blair House and maybe a trip to Capitol Hill. He’s been invited anyway; he ‘s not sure he can go. Then it’s back to the embassy for a black tie dinner where he is to give remarks before 130 people or so, including Senators, members of the US Supreme Court and other Washington A-Listers.

Friday it’s back to campus, where Lefkowitz speaks to the Duke University Board of Trustees meeting in the morning and then joins the board for a social event at Hart House in the evening. Saturday, his synagogue honors him. Sunday he packs.

“And then Stockholm? Fuhgeddaboudit.”

Guests raise a toast to Alfred Nobel at the 2011 banquet. (Nobel Foundation 2011)

Lefkowitz’s sojourn in the Swedish capitol includes a whole week of Nobel Festival events leading up to the Monday, Dec. 10 award ceremony. Among other things, he is to give a formal half-hour lecture for posterity and visit a local high school. There’s also the matter of a 5-minute toast at a white-tie dinner with the King of Sweden, which his co-laureate Brian Kobilka was only too glad to let him handle.

“They said 3 minutes, but I watched 15 of them online and the mean was 5 minutes. So mine is 4:45.”

On Monday, Dec. 10 — the 116^th anniversary of Alfred Nobel’s death — Lefkowitz will formally receive the medallion, a certificate, and “a document confirming the Nobel Prize amount” with his colleague and former student Kobilka in a white-tie and tails ceremony in the lavish Stockholm Concert Hall.

The Swedish Royal Family: (left to right) Queen Silvia, King Carl XVI Gustaf, Crown Princess Victoria, Prince Carl Philip and Prince Daniel. (Nobel Foundation 2011)

Laureates each receive only 14 tickets to this event, which is fewer than Lefkowitz has family members, unfortunately. But even though they can’t get tickets, many Lefkowitz and Kobilka alumni from all over also will be coming to Stockholm, just to be close to it. They’ll have their own reception elsewhere during the week, Lefkowitz said. And then on Dec. 11, there’s yet another white-tie dinner with the King and Queen — in the royal palace this time.

WHERE TO SEE IT

If you weren’t one of the lucky 14 people to get a ticket from Bob, Duke is hosting a viewing party for the live webcast of the Nobel ceremony from 10:30 a.m. to Noon on Monday, Dec. 10. in Schiciano Auditorium A&B. (White tie and tails are optional.)

You can also tune in wherever you might be that morning at http://nobelprize.org. The prize committee has not decided yet whether the 90-minute Nobel Banquet Highlights program will be made available on the web. It will be broadcast on Swedish television.

Learn more about Lefkowitz’s research and mentorship on Duke Today’s special site.

Here’s the hardware, baby: Linus Pauling’s Chemistry medal from 1954.

Soft Matter, Or Just Marshmallows?

By Ashley Mooney

On November 16, 2012

In Chemistry, Science Communication & Education, Students

By Ashley Mooney

When a chemist whisks cake batter, he’s not just thinking about the deliciousness that awaits. Whisking can actually induce chemical reactions integral to the texture of the dessert.

In a class being taught next term, Patrick Charbonneau, assistant professor of chemistry and physics, will help students apply science to creating edible masterpieces. For example, they will make two traditional Quebec desserts as an experiment in phase transitions. The ingredients in both are essentially the same, Charbonneau said, but one requires whisking while the other rests as it cools.

Students will measure the stiffness of marshmallows using chocolate bars, maybe it will end in a gooey s’more.

“By whisking you actually induce micro-crystallization and in the other one you remain in the glass phase, so the texture is completely different,” he said. “They’re going to be cooking—these are real desserts and real recipes—but the science is very controlled.”

Charbonneau works in a sub-discipline of chemistry called “soft matter,” but this doesn’t just mean marshmallows. The subject combines aspects of chemistry, physics, chemical engineering and material sciences—and fits perfectly with the science of cooking.

“The demos [in the class] are centered on food, so one of the cool ones is this material properties experiment measuring the [stiffness] of marshmallows using a chocolate bar,” Charbonneau said. “The chocolate bars are calibrated—you know their weight—and you just need a ruler to measure how much the marshmallow compresses.”

Although Charbonneau usually teaches an advanced physical chemistry course, he said he rediscovered old cuisine—and the science behind it—with the help of his friend from college and chef Justine de Valicourt, who is a visiting artist at Duke. De Valicourt has an undergraduate degree in biomedical sciences, but opted for culinary school rather than medical school. She will teach the cooking components of the seminar.

The class will meet once a week in spring semester for two and a half hours, with the first half dedicated to theory and food-centric demos, followed by cooking experiments and a dinner run by de Valicourt.

While cooking may make science more appealing to the non-scientists at Duke, Charbonneau said a basic understanding of chemistry is required in order to discuss the material in detail.

“Sure there’s the detailed chemical reaction when you’re browning something, but browning is not the entire thing,” he said. “There are some structural issues, and taste is something that is much more complicated than just a chemical that touches a receptor—there’s a texture, there’s a look.”

Since there is limited space in the kitchen—and thus limited space in the class—Charbonneau said he hopes he can make the topic more accessible to the Duke community through de Valicourt’s office hours and a final banquet.

“The students from the class will help with the cooking and serving of the banquet,” he said. “It’s the chef’s job to be able to teach them (how to cook properly) and to supervise them, so that should be fun. Hopefully we’ll be able to reach as many people as possible. We got amazing support from everybody in the administration that we talked to. I’m very grateful.”

Since bringing together a chef, a chemist and class space took a “special alignment of the planets to make it happen,” the class—which is being taught for the first time in the spring—may also be its only run.

“The chef is here for a semester, and I would never have dared—because I’m a theorist—to do a thing like this without her or the TA’s,” Charbonneau said. “I do hope though that some of the material we’ve built up will be able to be used as a special topic in general chemistry. I would like to have a module where I would be able to reuse the demonstrations and the content, and maybe even bring in a local chef at that point who would be interested. That’s one way to project it in the future.”

For those interested, the course is called Chemistry and Physics of Cooking, listed as Chem 89.

“It’s listed under chemistry, but it’s really about chemistry and physics,” Charbonneau said. “We’re looking at more physical chemistry—physics processes, denaturing of proteins. We’re also looking at the material science idea, such as viscosity, elasticity—viscoelastic moments, which chemists would never talk about… in a general chemistry class.”

Science Under the Stars!

By Pranali Dalvi

On October 23, 2012

In Biology, Chemistry, Science Communication & Education, Students

By Pranali Dalvi

The 8^th annual Science under the Stars, held in the lower lobby of the French Family Science Center, brought together several Duke departments, research groups, and organizations. Kids of all ages were busy participating in hands-on science activities.

Bioluminescence demo by Dr. Hendricks

Lab administrator Dr. Diane Hendricks had a station to illuminate the bioluminescent properties of Pyrocystis fusiformis, a marine dinoflagellate. Dinoflagellates bioluminesce when their cell wall is exposed to sheer stress, which triggers the light response. When asked why dinoflagellates glow, some kids hypothesized that dinoflagellates glow to look larger and more threatening so they can ward off predators. Scientists mistakenly thought so for a while, too. However, scientists now favor the burglar alarm hypothesis, based on the idea that the enemy of my enemy is my friend.

“Rather than trying to scare away the predators, they are actually attracting the predators of their predators,” Dr. Hendricks explained. Because the color blue is most easily seen in the ocean, many sea creatures bioluminesce blue. As a memento of Dr. Hendricks’s demo, kids were able to take home glowsticks of various colors!

The physics department showed students how to make Oobleck. Oobleck is a mixture of 2 parts corn starch and 1 part water. It displays shear thickening behavior, meaning that its viscosity – or resistance to flow – increases with shear rate. When the shear rate is low, the corn starch grains can easily move past one another and oobleck flows easily. However, under high shear stress, the corn starch grains pack tightly together and prevent the flow of grains past one another.

The process of preparing oobleck

Oobleck is an example of a non-Newtonian fluid. Non-Newtonian fluids are those whose resistance to flow changes according to the force that is applied to the fluid. One application of non-Newtonian fluids is in the soles of running shoes. The sheer thickening fluid hardens in response to the forces exerted during running or walking.

A favorite stop for the kids was CSI Durham presented by the Department of Evolutionary Anthropology and Anatomy. Students were required to perform cranial, pelvic, and femoral assessments to identify who the “missing victim” was. The skull and pelvis have distinct features in males versus females, and the femoral head and length diameter predict stature pretty accurately.

The event was sponsored by the Chemistry Department and organized by Dr. Kenneth Lyle.