Monday, December 12, 2011

Cheese making

This past weekend a few friends decide it was time to make their own mozzarella cheese. They went to a local cheese store (who knew those existed!), bought a kit, and went to the grocery store to get a few gallons of milk. They brought the milk to room temperature on the counter, mixed various ingredients, followed the specified steps, and low and behold they ended up with cheese!

They actually had to do two attempts because on the first try they forgot to add an apparently critical component at the right time- the citric acid.

When they forgot to add the acid the milk didn't curdle, and the cheese never formed. Curdling is when the proteins of the milk tangle together, to form solid masses. During this process the milk turns into curds and whey, with curds being the solid, and whey being the liquid.

Another fascinating step involved stretching the cheese curd (as opposed to the liquid whey that was drained off). This stretches the proteins in the cheese to make it a stringier, even though in mozzarella it is not supposed to be very noticeable. String cheese, which is often mozzarella, also takes advantage of this stretching and stringiness to make it a more fun snack.

Watching the two in my kitchen work away to make the cheese was a fun process for them and for me, but in the long run I believe it is probably more efficient and cost-effective to just buy the cheese at the store.

Sunday, November 27, 2011

Tired of Turkey?

As the turkey was put away, the cranberry sauce packed into tupperware, and the dishes cleaned up Thursday, Americans across the country shared a collective yawn.

Before I get into this post- you may or may not have heard of tryptophan and may or may not believe it to be the source of our Thanksgiving Day sleepiness. To this, I point out that the amount of tryptophan in turkey is high, but not significantly higher than other meats, and shouldn't induce sleepiness much more than eating a rack of ribs.

The sleepiness we find on Thanksgiving may have a number of causes, and turkey may be a part of it, but definitely doesn't work alone.

Normally, our brain absorbs tryptophan and glucose into the brain. The glucose is used for energy and the tryptophan is used to make hormones, nutrients, and chemical messengers.

On Thanksgiving day you just ate a ton of carbohydrates: rolls, stuffing, mashed potatoes, sweet potatoes, casseroles, gravy, cranberries, and pie. When we eat carbs our blood is full of extra glucose molecules.

To keep our blood at normal levels, our body makes insulin, which tells the muscles to clean up and absorb the extra sugars. The muscles do this, leaving the blood with lowered glucose levels, but still the same tryptophan levels. When our brain absorbs the tryptophan and glucose, it absorbs extra tryptophan because of the lowered amount of glucose present to absorb. The tryptophan goes down a chemical pathway, which ends with sleep-promoting melatonin in the brain.


I think its time for a nap now.

Sunday, November 20, 2011

Winter's coming- stay insulated!

Trying to think of a new blog post topic, I decided to ask friends what they wanted to understand the chemistry behind. One friend, Skylar, responded without hesitation to say the spray foam insulation.

Two chemicals come out of a spray gun and upon combining react to form polyurethane in an energy producing reaction. Poly(which means many)urethane(one type of organic compound) is many organic compounds (not urethane, but actually an organic compound called carbamate) linked together.

Upon hitting a surface the new mixture rapidly grows to fill the space it is in, growing to 100 times its original volume. This growth is what makes it so amazing to watch, as it expands from a line of liquid to a wall of solid foam.

Polyurethane comes in many shapes and sizes, determined largely by other chemicals added to the mix. To make spray foam so light and so large, the makers add a chemical that keeps space between the polyurethane molecules. This chemical is called a blowing agent. In many cases water is the blowing agent. With the energy from the combination of the sprayed liquids, water vapor is dispersed throughout the mixture as the foam forms around it. The water then turns into a liquid, leaving voids where it had previously been a gas.

The foam, because it has all these pockets inside, serves as a great thermal insulator and holds heat. In a house, the foam keeps heat from escaping the house, keeping energy bills low in the winter.

The foam is also a great insulator because of the rapid expansion it undergoes. When it expands so quickly, it fills every crevice, leaving few places for heat to escape through exposed walls.

Thursday, November 10, 2011

Poached Eggs

While I can't call myself an expert chef, I do claim to dabble in the culinary arts. I have always loved to cook, and my favorite meal (besides dessert) has always been breakfast. For the most part I think this is because I love baking, and breakfast has so many baked goods associated with it (muffins, coffee cake, pancakes, waffles, bread, scones).

With a love of carbs, eggs have never been my first choice as a breakfast option, but I have a friend and fellow amateur chef/blogger who decided to experiment with eggs. We decided to poach eggs, as that was something neither of us had tried before and looked just challenging enough to be fun.

The general idea of a poached egg is you crack an egg into a pot of hot water, and wait until the egg is cooked just enough to be delicious. We found a few different tips, that (no surprise!) have chemistry behind them if you look closely!

  1. Push the egg whites together to help the poached egg come out in one piece
    • An egg (especially the egg whites) is made up primarily of proteins, which are long molecules all folded up on themselves due to weak bonds within the molecule. When the proteins are heated up, these weak bonds are broken and the protein unfolds, but stronger bonds are formed as the different protein molecules all connect. By pushing the egg whites together, you are helping to create more of those stronger bonds, which keep the cooked egg together.
    • Another fun way to do this was to swirl the water before pouring in the cracked egg. The egg will swirl with the water until it settles down, and the centripetal force of the swirling motion pushes the egg whites together for you into a nice little egg packet.
  2. Add a teaspoon of vinegar to the boiling water to help the egg stick together.
    • The vinegar, like the heat, will break the original weak bonds of the molecule, and make the protein unfold and ready to form stronger bonds. By adding vinegar to the pot of water, when the egg is added, the proteins will be able to stick together faster, and keep it from separating into a white, stringy, watery mess.
  3. Heat the water to almost boiling, then cook for 4-5 minutes
    • If the water is too hot or you cook the egg too long, then the protein molecules in the egg whites form too many of those strong bonds to each other. When these bonds form, they push water out of the egg, which is what causes the egg to solidify. If too much water is pushed out of the egg, like when the egg is heated too long or too much, then it becomes tough and rubbery.
Poached eggs taste delicious (reminiscent of a yummy cheese sauce), are healthy, and not too hard to make. We ate ours over toast and loved it! Next time you are feeling adventurous at breakfast in the kitchen, I'd recommend a poached egg--it will surprise you!

Wednesday, November 2, 2011

Clarifying the fog machine

This past Halloween weekend people across America enjoyed fog machines as special effects in the movies or on TV, to spook the neighbors, or to enhance a haunted house. What is this weird artificial cloud? Where does it come from? How does it work?

Chemistry has all the answers.

Fogs are created by the dispersion of small liquid particles. For artificial fogs, the most common type of fog fluid is made of water and glycols. A glycol is a chemical compound containing oxygen and hydrogen groups that are attracted to water molecules like magnets. The result is intermolecular hydrogen bonding which connects the water molecules to glycol molecules. When these two liquids are heated inside the fog machine, the water particles convert to gas at their boiling point (100°C) and the glycol substances remain liquid, as their boiling point is upwards of 180°C. Because of the intermolecular hydrogen bonding that latches the particles together, the gas released from the fog machine is visible because the gaseous water molecules have liquid glycol molecules attached to them.

While the fog may be spooky, their is no reason to panic. There is nothing magical about its creation. Just the clever application of chemistry in the special effects world.

Saturday, October 22, 2011

Computers Knowing How Humans are Remembering

Standing in the grocery store, trying to remember the shopping list left at home, our brains employ a variety of memory systems to assist in the recall process. Now researchers are finding that they can use computers to model these same memory systems humans use to remember an event.

When the brain is attempting to remember an event, it is retrieving from memory not just that single event, but also everything surrounding that event, the context. By studying the contexts applied in remembering, the computer models are able to replicate human data, according to the study published in Neuropsychologia in January 2012.

According to Ehren Newman, a memory researcher at Boston University, “Computational models provide a means to understand un-intuitive patterns in the data.” By better understanding human memory systems, there are hopes that researchers will be able to hone in on understanding specific aspects of memory.

One such aspect includes tracking changes in memory retrieval as our brains age. As we age, our ability to recall memories generally decreases, but with this computer model it may be possible to identify which memory systems are not being employed as they were in younger years. Looking at younger and older memory data for a patient allows researchers to compare what changes in brain activity create the memory deficiencies. Understanding and being able to predict typical memory decline may lead to being able to identify unusual decline and use that identification to predict potential memory-related illnesses.

In addition to using this understanding to see how our memory systems change over time, this information could be used to see how the recall process is different for schizophrenic or amnesic patients, and address the cognitive problems associated with those illnesses.

“Many researchers are looking at how the brain is organizing recall underlying the memory process,” says researcher Joshua McCluey, “But not many are looking at free recall with an fMRI.” By looking at blood flow to the brain, an fMRI makes it possible to look more closely at what the brain is doing and monitor neural activity, which leads to better results. Because the results found are for free recall, which is when a participant remembers items in no particular order, the data gathered is more complex and representative of human experience.

To better understand how memory works and hopes to apply this understanding to issues like memory loss, schizophrenia, and amnesia, researchers at Vanderbilt University are studying the brain both when an event occurs and when it retrieves that same event from memory. This data is then used to develop a computer model of human memory.

The researchers generated memories for each participant by having her read a list of 12 words and mentally decide whether the object would fit in a shoebox or mentally decide whether the object is alive for each item on the list. Making this judgment serves to help solidify the memory in the brain. Meanwhile, an fMRI machine scanned each participant’s brain to see how it stored those memories. Later each participant was asked to recall every item on the list to the best of her ability. Again, during this recall portion of the test, the brain was scanned to see how the memories were retrieved.

Patterns that were observed and modeled by the computer include recency effect, which shows memory preference for items at the end of the list, the items most recently read. They also found a contiguity pattern, where participants are more likely to remember the word appearing immediately around, especially after, the previously recalled word. When they applied all the different patterns they discovered to the computer model, they were able to see that the computer, with good accuracy, could replicate the way that the human brain remembers events.

While this computer model can duplicate human memory, it cannot serve as a substitute for human memory and won’t help you suddenly remember those grocery items you’ve forgotten to purchase. It may, however, serve as a way to better understand what goes into making and recalling memories as researchers try to wrap their minds around the brain and how it functions.  

Monday, October 17, 2011

Finding the sources

So for my last post, I had quite an experience finding the necessary sources. I ended up talking to Dr. Lukehart, the primary research contact I had, because he was my professor for Nanochemistry, which was one of my favorite Vanderbilt science classes and a large part of that was his excitement about the topic. I found a paper he had recently published, and decided to talk to him about it. He was so easy to talk to and ask questions of, and gave me the lock and key metaphor I was really proud of in the article.

For my second source, I had a bit more trouble. I emailed Dr. Wright, another one of my professors at Vanderbilt. He taught BioInorganic Chemistry, which is exactly where these nano-particles could be studied. They are used in human life (bio), they are metal (inorganic) and they are used by reactions (chemistry). The article was due Friday at 6, and 3 pm rolled around that day and he still hadn't gotten back to me. I decided to go to his office in person to find him and get a quote. As soon as I stepped off the elevator in the Chemistry building on campus, I saw him in a conference room talking to his graduate students. I waited outside the room for him, then as he came out got a chance to walk and talk with him to his office as he told me what he thought was important about the nanoparticles.

For my final source, Dr. Hallahan, I emailed him about finding a chance to talk, and his graduate student responded to me, and we set up a time for me to call. Unfortunately, the night before the phone call I found out that I would be on a roof, nailing up shingles at the same time our phone call was scheduled. For fall break I went on a service trip to Knoxville, and I accidentally figured the time change in the wrong direction. Oops. So I sent a quick email apologizing for the change of plans and a few questions I was going to ask in the hopes that he would still respond over email. Lucky for me, he did, and I got the information I needed to finish the article in time for my second deadline.

Finding sources was definitely the most difficult part of writing this article, but I can see how it paid off in the final product. I'm pretty proud of my little news article.

Tuesday, October 11, 2011

Two-for-one: locate and kill cancer with a single agent

Scientists may have found a way to more accurately locate cancer cells and, at the same time, destroy them. New, nano-sized metal particles can bind to tumor cells, emit a fluorescent glow, and then be heated with a magnetic field to kill nearby cancer cells. By uniting the process of imaging and treatment, therapy becomes more effective and targeted to the cancerous cells.

There are numerous methods of cancer imaging, many of which involve using an identifiable molecule that fits into a cancer cell receptor like a key fits into a lock. This process takes some time (in this study 48 hours), and requires that the molecule does indeed fit into the receptor of a cancerous cell, that the molecule can be distinguished during imaging, and that enough of those molecules are located in close proximity to recognize an increased concentration.

For years, researchers have suspected that nanoparticles are good candidates to improve cancer imaging because of the likelihood that more of them would bind to a tumor. In 2010 Dr. Lukehart, a Chemistry professor at Vanderbilt, showed that this was true by using nanoparticles made of iron and platinum. Each nanoparticle was covered with thousands of peptides,  molecules used to bind to a cancer cell. When the tumor is hit with radiation, the nanoparticles bound to cancer cells fluoresce, giving off light waves not visible to the human eye. A machine able to detect these waves is used to locate where they are coming from, to create an image of where in the body cancer cells are. The image created using nanoparticles was much brighter and easier to analyze than when single molecules were previously used. This improvement is because  when a peptide binds to a receptor, like a key fitting into a lock, there are thousands of metal molecules within the nanoparticle it is attached to. Since each metal molecule is giving off the light waves, the machine is able to detect thousands more light rays coming from each location where a peptide is bound to a cancer cell.

Researchers outside Dr. Lukehart's lab see the advantage of this technique. “This technology is cool,” says Dr. Wright, a bio-inorganic chemist at Vanderbilt who did not participate in the research,“ It let’s us see how well radiation is going.”

Using these nanoparticles to image cancer in the future is likely, not just because of the superior images that result, but also because of the possibilities of treatment using these same nanoparticles. The iron and platinum nanoparticles used are paramagnetic, which means they line up in magnetic environments. By rapidly reversing the polarity of a magnetic field, the nanoparticles will create heat, which can kill the cells located nearby.

The platinum part of this nanoparticle introduces another way that this drug could be used to treat cancer. Platinum has been shown to be an anti-cancer chemical. In fact, the anti-tumor properties of the element are already in use in the platinum-containing chemotherapy drug, Cisplatin, used to treat testicular cancer. By using nanoparticles that both contain platinum and are surrounded by peptides which link to cancer cells, as was done in this study, it is possible that the simple introduction of this imaging agent into the body could serve to treat cancer without any external influence.

Dr. Hallahan, head of the Department of Radiation Oncology at Washington University School of Medicine in St. Louis, suggests, “These nanoparticles will first be used for patients with poor prognosis cancers. These include patients with recurrent disease and patients with [inoperable] cancers.” Treatment with these nanoparticles fills an unmet medical need, as there are “no treatment options for most of these patients.”

In this particular study, only the imaging abilities of nanoparticles were analyzed and only lung cancer was investigated. According to Lukehart, however, this method could be easily adapted for other types of cancer by simply changing the peptide linker to one that binds to the targeted cancer cell.

The largest obstacle in the way of getting this imaging technique and treatment to patients is the creation of these nanoparticles. Scaling up their production  is not only difficult, but expensive, and could hold back the application. Lukehart hopes, however, that “if there are really hot results in future research, we may see it in place in only a couple years.”

Monday, September 26, 2011

Football Chemistry

This past weekend I attended my first NFL football game, in Nashville, TN, where the Tennessee Titans played the Denver Broncos. As a native Tennessean, I naturally rooted for the Titans who ended up pulling out a win against the favored visiting team.

Don't be confused. This blog is not about sports or my social life, but about making visible some of the invisible processes that make our world the fun-filled, exciting world that it is. Changing the mysteries behind life to predictable patterns that make all the pieces come together.

So why do I start off talking about football? I am a firm believer in the idea that Chemistry can be found in everything we do, and I am determined to prove this. Go ahead- try and find something we do that isn't touched in some way by Chemistry. Even football.

That said, let's take a closer look at football by looking at the most important player in the game: the football. This brown foot-long ball commonly called a pigskin is, in fact, not made of pork-products, but rather cow hide. The process of forming the leather is quite chemically intensive and a multi-step process.

The most complex step is that of tanning. For stiffer leathers like that used in a football, the process involves using either a vegetable or synthetic tannin. Vegetable tannins, a class of chemicals, can be found in nature in the bark and leaves of plants. The tannins, molecules which are typically negatively charged and contain many oxygen-hydrogen branches off the molecule, connect to proteins in the cow hide and make it more flexible, more water-proof and less prone to bacterial attack.

Tannins are just one piece of the puzzle in the whole leather-making process, which involves many different chemical procedures. Performing all those procedures, including the tanning process, cutting out four oval-shaped pieces, attaching some lining, labeling, and thread, and filling with air has given us an ever-changing, unpredictable, enthralling sport that never ceases to captivate audiences, including me, across the country.