To diagnose prostate cancer, urologists and pathologists use biomarkers, which are biochemical signatures in blood, urine and tissue that suggest the disease may be present. Engineer Brian Denton is working with urologist John Wei and pathologist Scott Tomlins to develop a quicker and less expensive way to evaluate biomarkers, using computational models. Read more.


It’s after school, but this building in downtown Oakland, Calif., is buzzing with enthusiastic teenagers looking to learn. Welcome to Youth Radio, part of a youth media project funded by the National Science Foundation to engage underrepresented 14-24 year olds with training and hands-on experience in engineering, and the social, physical and biological sciences. Read more.


Crystal of the Week: Citronella

It’s the time of year when mosquitoes seem to outnumber humans. We often go to great lengths to find the perfect pest repellent, allowing us to remain outdoors and enjoy our favorite summertime activities, whether it’s fishing and camping, swimming and tennis, or a leisurely picnic with friends. With summer’s ever-present mosquito battle in mind, we chose citronella as this week’s crystal.

People are accustomed to seeing citronella as an oil or spray, so it may be hard to believe it could be a crystal. But think about butter, which has a similar chemical structure: At warm temperatures, butter melts. At cool temperatures, butter solidifies.

Compared to butter, the citronella molecule has a really short backbone of single-bonded carbon atoms, with one terminal oxygen atom. (If citronella were a fatty acid, like butter, we could call it “saturated” because the carbons have as many hydrogen atoms attached as possible.) Because the molecule is so small and composed of so many lightweight atoms, it has a low vapor pressure, which means that it evaporates easily when warm. That’s good news for repelling mosquitoes.

According to the Environmental Protection Agency, oil of citronella was initially registered in 1948 as an insect repellant under the name of McKesson’s oil of citronella. It had human applications (as in you could use it on your body, hair, clothing and footwear) to repel adult gnats and mosquitoes. Citronella is a biochemical pesticide with a non-toxic “mode of action.” Some studies have shown it to be effective in deterring lice and the mosquitoes that cause Dengue Fever.

These days, citronella is found in “natural” insect repellents, candles, deodorants and perfumes, astringent skin cleaners, and aromatherapy aimed at addressing nervous fatigue and headaches. 

A side effect of the oil is that when directly applied to human skin, it has been known to cause irritation. The warm sensation it creates on the skin has also purported benefits for joint pain.

Want more info on repelling mosquitoes? Check out this Science Nation video about Vanderbilt University researchers working to unleash a more-powerful-than-DEET insect repellent. The EPA also has great resources on mosquito control.

Top photo: An Asian Tiger mosquito. Credit Ary Farajollahi, USDA Forest Service

Middle photo: An aerosol spray canister. USDA researchers Lyle Goodhue and William Sullivan invented the aerosol spray canister, dubbed the “bug bomb,” to dispense insecticides. The design, patented in 1943, is the ancestor of many popular commercial spray products. Pressurized by liquefied gas, which gave it propellant qualities, the small, portable can enabled soldiers to defend against malaria-carrying bugs by spraying inside tents during World War II. Propellants used in these older aerosol cans have since been replaced with environmentally friendly ones. Credit: USDA

Bottom photo: A Culex species mosquito biting a human hand. Credit: Bob Dusek, USGS


Until now, biofilms—colonies of microbes like bacteria that grow together in a matrix produced by the cells themselves—have been poorly understood. Yet, they can be costly and dangerous. Dacheng Ren and colleagues at Syracuse University are working to better understand how biofilm cells communicate. Read more.


What the microscope did to unlock the secrets of biology, the “chemiscope” is intended to do, to revolutionize chemistry. The ultimate goal for chemist Ara Apkarian and colleagues is to observe chemistry in the act, to see the making and breaking of bonds in real-space and real-time. Read more.


In a tsunami, devastation is created by far more than the wave itself. Debris that hits homes and other structures plays a huge role in a tsunami’s destructive power. Engineers from across the country have teamed up to design and carry out a series of large-scale tests aimed at better understanding exactly what happens when debris strikes. Read more. 


Working to understand how brain circuitry controls how we move, bioengineer Gert Cauwenberghs and his colleagues are hoping to develop new technologies to help patients with Parkinson’s disease and other debilitating medical conditions. Read more. 


Imagine robots no bigger than your finger tip scrambling through the rubble of a disaster site to search for victims or to assess damage. Using insects as inspiration, engineer Sarah Bergbreiter and her research team at the University of Maryland are building micro-robots to traverse rough terrain at high speeds. Read more.


Hoping to contribute to the next generation of robotic fish and underwater submersibles, aerospace engineer Michael Philen and his team at Virginia Tech are investigating the biomechanics of fish locomotion. Read more.


Nearly 40 years of satellite imagery reveals that west Antarctic ice shelves floating in the Amundsen Sea are steadily losing their grip on adjacent bay walls. The research, by glaciologists at The University of Texas at Austin, suggests that the retreat pattern could potentially amplify an accelerating loss of ice to the sea. Read more!

Caption: Rifts and surface crevasses near Pine Island Glacier’s grounding line.
Credit: Ian Joughin, University of Washington

Solar panels are becoming a familiar site in communities across the United States, but what about solar fuels? Chemistry professor Harry Gray and NSF’s CCI Solar are working to make solar fuels a viable option in the future. Read more.


A team of mathematicians from San Francisco State University and the University of North Carolina, Charlotte, has used mathematical modeling to uncover new clues to the three-dimensional organization of mitochondrial DNA in trypanosomes.

Trypanosomes are microscopic, unicellular parasites responsible for widespread, fatal diseases including sleeping sickness. This neglected disease, transmitted by the tse-tse fly, threatens millions of people in sub-Saharan Africa. Its western counterpart, Chagas disease, affects an estimated 8 to 11 million people across North and South America. Read more!

Caption: Network of oriented flat minicirles on a square grid. A tightly packed grid yields high levels of interlocking to form a large network of minicircles. This provides a model for the organization of DNA minicircles in the mitochondria of trypanosomes.
Credit: Javier Arsuaga, San Francisco State University