This post is long overdue, both because I haven’t posted in more than a month, and because I’ve actually had this research highlight written since January – it was one of the writing samples I submitted for my application to the AAAS Mass Media Fellowship this spring.
I’m pleased to say that I’ve received the fellowship this year, and will be spending the summer writing for the Milwaukee Journal Sentinel before heading off to do a postdoc in the fall. This will make my graduation & moving plans a little complicated, but I’m really excited about this opportunity.
At any rate, I’ll keep you updated as I go, but for the moment – zebrafish!
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Shining Light on the Toxic Effects of Nanoparticles
Exposure to light and tiny titanium dioxide nanoparticles can be a lethal combination – at least, if you’re a zebrafish.
According to researchers at the University of Wisconsin-Madison, raising zebrafish in water containing titanium dioxide nanoparticles and exposing them to light caused the fish to be badly deformed and die much more quickly than fish raised in normal environments.
Understanding the toxicity of these materials is critical because titanium dioxide nanoparticles are finding their way into a growing range of consumer products.
Titanium dioxide nanoparticles are especially useful in sunscreens, because they effectively absorb harmful UV rays without making the sunscreen pasty and opaque. However, similar nanoparticles also form the foundation of some next-generation solar cells and are used to treat wastewater in sewage plants.
Yet according to the researchers at UW-Madison, nobody really knows what effects these nanoparticles have when they get out into the environment.
The UW team explored this question by raising zebrafish embryos in water containing titanium dioxide nanoparticles. They kept some fish in the dark and exposed others to light to see whether or not light exposure changed the nanoparticles’ effects.
Other researchers have studied nanoparticle toxicity using isolated cells grown in the lab. However, the toxic effects on cells in a dish can sometimes be different than the effects on a whole organism.
By using zebrafish, the researchers at UW-Madison were able to look at the toxicity on a larger scale. Zebrafish are ideal for these sorts of experiments because they grow quickly. They are also clear, so the researchers can easily see any growth defects that appear.
Researcher Ofek Bar-Ilan and coworkers found that fish exposed to the nanoparticles but kept in the dark looked normal. Fish exposed to the nanoparticles and kept under bright light, however, had deformed heads and tails, and their growth was stunted. The fish exposed to both nanoparticles and light also died much more quickly than fish kept in the dark.
For something so small, the nanoparticles seemed to do a lot of damage.
So, on Wednesday, I told you about an experiment that my friend Tracey and I did to look at the effects of different flour-weighing methods on cookie consistency (and taste!). I left you hanging right after telling you about our baking procedure, but never fear: the rest is coming today. So, without further ado:
Results and Discussion
1. Visual appearance & spread
Batch 1 (sifted flour) appeared thin and nicely browned. Batch 2 (scooped flour) did not spread as thin as Batch 1 and browned nicely on the edges but remained poofy in the center. Batch 3 (packed flour) only browned on the very bottom and was very poofy (almost appearing uncooked) on the top. Photographs of the 3 different batches are given below.
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- Cookies straight out of the oven. From left: cookies made with sifted, scooped, and packed flour.
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- Cooling cookies on an elevated drying rack. From left: cookies made with sifted, scooped, and packed flour.
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- Pac-man cookies? From left: cookies made with sifted, scooped, and packed flour.
We also quantified the spread of the different batches by measuring their diameter with a ruler. The diameters as a function of flour content are reported below:
Cookie diameter as a function of mass of flour used. Probably should have reported the x axis as percent weight rather than absolute weight, but didn’t weigh the entire batch!
We found that cookies made with less flour spread more during the baking process – we suspect this is because the flour soaked up a lot of the liquid (fat & water) in the dough and dramatically decreased its viscosity, but we didn’t have a good way to check this in our experiment.
2. Taste-test obsevations
A few months ago, I got a new cookbook and was delighted to find that the author included weights for all of her dry ingredients. While measuring dry ingredients by weight is de rigeur in Europe, it’s somewhat uncommon in the US.
But as a chemist, weighing my dry ingredients rather than measuring them by volume is almost second nature. In the lab, we always measure powdered chemicals by weight, because their volume can vary a lot depending on how tightly they’re packed!
This isn’t something that we usually worry about too much in the kitchen, but it can make a big difference. So, my lab-mate Tracey and I recently did a little kitchen experiment to demonstrate how much different measuring techniques can affect the final properties of a dish.
We chose to study chocolate chip cookies, because really, who doesn’t like cookies? (Also, we were sort of inspired by this experiment). The idea behind the experiment was simple: make three batches of cookies, and measure the same volume of flour by different methods in each batch.
In one batch, we would sift the flour; in another, we’d scoop it like normal, and in the third we’d pack it tightly in the measuring cups. We hypothesized that sifting the flour would give us much less flour (by weight) while packing it would give us much more. We also hypothesized that the amount of flour in the cookies would affect their texture, with more flour leading to dryer, denser cookies.
Clearly, this is important research, necessary to baking enthusiasts everywhere, right? Good – glad you agree! Without further ado, I’ll walk you through our procedure and our results… it’s like a lab report, but way tastier 
Tracey is ready to make some cookies – are you?
Read more…
As I mentioned in my last post, I wrote a “news story” for a fellowship application about new materials for lithium ion batteries that I really wasn’t happy with. However, I realized after canning the story that the notes I wrote for myself – in the format of a series of questions followed by answers culled from the paper – were actually kind of a neat research highlight on their own.
So, I’ve rewritten them in a readable format, and in reasonably general terms. Take a look – I’d love some feedback on whether this version “works” or not.
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1) So what’s the big picture? Who did this experiment, and what did they study?
This paper was on an experiment done by Linsen Li and Fei Meng in Song Jin’s research group at the University of Wisconsin-Madison. Jin’s group investigated whether a new material (nanowires made of a compound called ferric fluoride) could be used to make better cathodes for lithium ion batteries.
2) Don’t we already have good lithium ion batteries? Why do we need to make them better?
Lithium ion batteries have a pretty high energy density. This makes them really useful for portable devices where we want to be able to carry around lots of stored energy without much weight.
However, current lithium ion battery technologies have limited storage capacity. Their capacity is fine for relatively low-power devices like cell phones and laptops, but they generally can’t supply enough energy for large-scale applications like electric vehicles and storage on the power grid.
New materials (like the ferric fluoride nanowires in this paper) have the potential to solve these problems. Using these types of new materials, we might be able to make lithium ion batteries that can store more energy and are more useful for large-scale energy needs.
3) Why is ferric fluoride useful?
As some of you know, I recently applied for the AAAS Mass Media Fellowship (okay, technically called the “AAAS Mass Media Science & Engineering Fellows Program”, but that’s a mouthful). The application required two writing samples. The first was allowed to be on any topic and in any style appropriate for the general public; I submitted a revised version of this post.
The second writing sample was required to be a “news article” on a recent paper from the scientific literature. Unfortunately, most of my articles for the Daily Cardinal weren’t recent enough, but while browsing through journal abstracts I found a neat paper recently published by a couple of research groups here at UW-Madison and decided to write on that instead.
But… it turns out that UW-Madison doesn’t actually have a subscription to the journal this paper was published in(*).
So, I ended up writing my story off a proof borrowed from one of the authors. But as I pulled all my application materials together a few days the deadline, I realized that I needed an official copy of the paper to submit with the application (the proof I was using didn’t have the publication date on it), and I panicked a bit because I wasn’t sure that interlibrary loan would come through in time.
Which meant that I ended up hurriedly sifting through my feed of recent UW-Madison research, found an interesting article, and wrote a backup story.
I’ve been silent on this blog and on Twitter for over a month now, mostly because I’ve been preoccupied with other things. Applying for postdocs and a fellowship, writing papers, even performing in the Nutcracker(*) – you name it, I was probably doing it.
But, while I’ve still got some work to do on my postdoc applications, and there are always more papers to be written, I’m determined to get back to this blog in the new year. My goal last year was to average a post every two weeks, which I didn’t quite manage (I wrote 16 science-related posts and 5 articles for the Daily Cardinal over the 11 months since starting this blog), so I’m going to try for that again this year, and hopefully I’ll make it this time.
I have plenty of ideas – and several half-written posts – floating around on my Google Docs account, so it’s mostly just a matter of making myself sit down and write. Prod me if I start to fall behind, okay?
In the spirit of “catching up”, I spent half an hour yesterday reading through all of the items in my RSS feeds that I neglected over the holidays. In particular, I have a feed that sends me the titles of every single science- and medicine-related paper published by UW-Madison researchers each week. This feed averages 90 to 150 items a week(+), and when I logged in to Google Reader this week I found 345 unread items.
There are a couple of pretty cool topics in there, ranging from using nanowires to make high-capacity cathodes for lithium ion batteries to studying whether giving birth to twins affects cows’ future reproductive success.
But my favorite, by far, is a paper from food science in which the authors studied chocolate chip cookies. I couldn’t resist writing a short research highlight on this one just for fun… because really, how cool is it to bake chocolate chip cookies for research?!
When I picture my mother’s kitchen at home in California, I see sunlight streaming through the window above the sink. I see her red Kitchen Aide, the white stovetop, and the oven and fridge bookending the narrow galley kitchen. And on the bookshelf above her kitchen counter, I see a familiar red book.
This book is one of the few books I know is on my mother’s kitchen bookshelf, and surprisingly, it’s not a cookbook. Instead, it’s Harold McGee’s On Food and Cooking, which is easily one of my favorite chemistry books of all time.
(Yes, this is actually a photo of my mother’s kitchen bookshelf, delivered from California by the magic of an iPhone and the internet.)
Harold McGee has been a fixture in my mom’s kitchen for as long as I can remember. We frequently referenced him during our kitchen adventures when I was growing up. Want to know why whisking eggs and oil makes a nicely emulsified mayonnaise, while whisking water and oil just makes a quickly-separating mess? Look in Harold McGee. Want to know why melted chocolate siezes and gets really gross if you add too much liquid? Check Harold McGee.
Sometimes, it felt like we were on a first-name basis with him. It wasn’t just, “look it up in Harold McGee,” but instead, “ask Harold!” It was as if he was a trusted friend and teacher, standing by to answer even our most mundane kitchen chemistry questions.
The answers often straddled the border between simple and magical, and if you kept reading, you almost always learned something new. Mayonnaise forms a nice emulsion, for example, because egg yolks contain proteins and other molecules that coat oil droplets and help keep them suspended in water. But did you also know that when you beat a single tablespoon of oil into a mayonnaise, it gets broken up into something like 30 billion tiny droplets?
When I started thinking about topics for this week’s food chemistry carnival, I pulled out my copy of McGee and turned to the section on pastries, thinking it would be fun to write about what exactly it is that makes the perfect pie crust (which, it seems, is a popular topic this week – for the record, my favorite is the Cook’s Illustrated vodka pie crust!). But as I started flipping through the book, getting sidetracked by countless other tidbits of food-related information, I realized that I really just ought to write about On Food and Cooking itself.
As a past recipient of the NSF Graduate Research Fellowship, I tend to get a lot of questions from students in my department about how to write a good application – particularly this time of year, as the fellowship application deadline approaches.
There are already a lot of good sources for advice on the internet (particularly here and here, and lots of good links here, to name a few), but I want to add my thoughts as well. In a nutshell, the four points I find myself repeating year after year are:
- Look at previous winners’ applications
- Ask someone to read (and critique) your proposal
- Pay attention to Broader Impacts
- Apply early and apply often
I’ve explained each of these points in more detail below. Advance warning, but this post is pretty long – feel free to jump ahead if there’s a section you’re particularly interested in.
Read more…
When I was in elementary school, I wanted to be a particle physicist. My fifth grade class took a field trip to the Stanford Linear Accelerator Center, and I was fascinated by the fact that it took such giant machines to investigate phenomena occurring on such tiny scales.
Fast forward 15 years. Somewhere along the way, I got sidetracked by chemistry, but there’s still a part of me that is inexorably drawn to these beautiful experiments digging down into the fundamental science underlying our world.
So with that in mind, perhaps you’ll understand why I was excited – and a bit apprehensive – to be asked to write about the Higgs boson and the role played by UW-Madison researchers for yesterday’s issue of the Daily Cardinal.
I was excited, because it was a perfect excuse to email a particle physicist, ask for an interview, and go pick his brain. I spent about 40 minutes talking to UW physics professor Wesley Smith last Wednesday, and he gave me some useful (and interesting) insights into the parts of the Higgs story that I’ve found confusing.
But I was also apprehensive, because particle physics, and especially the Higgs boson, is an incredibly complicated topic – how can you possibly do it justice in just 600 or 700 words?
When I was preparing my Nerdnite talk and Lasers in SF posts back in February, I did a lot of reading, ranging from a textbook on laser processing of materials to a novel about the Death Star.
All of these books were interesting and useful, but the one standout on the list was Michio Kaku’s Physics of the Impossible. This is by far one of the best books I’ve ever read on the science of science fiction, and I highly encourage you to give it a go.
Kaku structures the book around three different classes of “impossibilities.” He starts with what he calls “Class I impossibilities,” which are technologies that aren’t possible today, but which don’t violate any of the known laws of physics and might be possible with the right scientific advances. In this section, Kaku devotes each chapter to a different technology, and does a fantastic job of helping us think through how technologies we have today might someday develop into the stuff of science fiction.
For example, in his section on psychokinesis, he mentioned that we already have the technology to implant computer chips into the brain to pick up neural signals, and that these signals can be used to control computers (or computer-controlled objects). Then he reminded us of an earlier discussion about room temperature superconductors and levitation. So what if, he asks, we could link these two systems together and use magnets to levitate objects simply by thinking? Sure, it’s not quite psychokinesis in the sense of pure mental energy, but it’s a way we might someday use technology to achieve the same effect.
These sorts of discussions gave Kaku a great venue for discussing the potential uses – and the limits – of a wide variety of up-and-coming technologies. In most cases, he also discusses the underlying science in clear, accessible language.
After the long section on Class I impossibilities, Kaku moves on to things that are decidedly more impossible. Read more…
