The American Chemical Society is offering a new service in hopes of making science more accessible to the public. Each week they issue a short collection of science articles, written in an interesting and engaging style, that you might use with your students to help them make connections between the curriculum and their own lives. The service is called Discoveries!, and it is free. At this point, the articles are not available on a website, but are emailed to ACS members. I am posting examples of the articles below with permission.
I am always on the lookout for science articles that I can share with my own students. I appreciate that these are written at a level any of my students can handle. Even better, if my students want to investigate further, they can access the original full text version.
Corralling stink bugs could lead to better wine
Journal of Agricultural and Food Chemistry
To wine makers, stink bugs are more than a nuisance. These tiny pests can hitch rides on grapes going through the wine making process, releasing stress compounds that can foul the smell and taste of the finished product. Now, in a study published in the Journal of Agricultural and Food Chemistry, scientists report the threshold of stink bugs per grape cluster that will impact the integrity of the wine.
In vineyards, brown marmorated stink bugs feed on grapes, reducing their yield and quality. And because they are small and blend in, the insects hitchhike on the grapes and wind up in the winery, giving off stress compounds that sometimes affecting the quality of the wine and juice. Pesticides used in the vineyard are not completely effective, so attention is being focused on ways to reduce the presence of the insects in wineries post-harvest. To find out exactly how grape processing impacts the release of stink bug stress compounds and how this affects wine, Elizabeth Tomasino and colleagues took a closer look.
The researchers placed varying numbers of live or dead stink bugs on grapes and measured the release of insect stress compounds as wine was produced from the fruits. The found that pressing was a key step in the release of two of the most common stress compounds — tridecane, which is odorless, and (E)-2-decenal, which produces an undesirable musty-like, coriander or cilantro aroma. Interestingly, white wine was contaminated less often than red. The researchers suggest that this is because these two wines are pressed at different points in the winemaking process. The team concludes that if winemakers could limit stink bugs to no more than three per grape cluster, the levels of tridecane and (E)-2-decenal in wine would be below the consumer rejection threshold.
The authors acknowledge funding from the National Institute of Food and Agriculture, U.S. Department of Agriculture and the U.S. Department of Agriculture, Northwest Center for Small Fruits Research.
Expanding point-of-care disease diagnostics with ultrasound (video)
ACS Nano
Fast, accurate and inexpensive medical tests in a doctor's office are only possible for some conditions. To create new in-office diagnostics for additional diseases, researchers report in the journal ACS Nano a new technique that uses ultrasound to concentrate fluorescently labeled disease biomarkers otherwise impossible to detect with current equipment in an office setting. The markers' signal could someday be analyzed via a smartphone app.
Ultrasound is a safe, noninvasive, inexpensive and portable technique best known for monitoring pregnancies. But these high-frequency acoustic waves can also be used to gently handle blood components, cells and protein crystals at the microscopic level. With an eye toward point-of-care diagnostic applications, Ton Huang, Zhangming Mao and colleagues wanted to harness these sound waves to help detect even smaller particles and biomarkers for diseases such as cancer that often require special laboratory equipment to detect.
The researchers developed an acoustofluidic chip that, though vibrations, can form a streaming vortex inside a tiny glass capillary tube using a minimal amount of energy. Testing showed that the vortex could force nanoparticles ranging in diameter from 80 to 500 nanometers to swirl into the center of the capillary. The nanoparticles captured biomarkers labeled with a fluorscent tag, concentrating them in the capillary to boost their signal. This increased brightness could make the signal readable with a smartphone camera.
The authors acknowledge funding from the National Institutes of Health and the National Science Foundation.
Watch the Headline Science video here explaining the diagnostic technique.
Using E. coli to detect hormone disruptors in the environment
ACS Central Science
Endocrine disrupting chemicals (EDCs) have been implicated in the development of obesity, diabetes and cancer and are found in a wide array of products including pesticides, plastics and pharmaceuticals. EDCs are potentially harmful, even at low concentrations, equal in some cases to mere milligrams dissolved in in a swimming pool full of water. Now researchers report in ACS Central Science that they can quickly detect environmentally relevant concentrations of EDCs using engineered E. coli bacteria.
Detecting EDCs can be tough because the classification is based on their activity — disrupting hormone function — instead of their structures. Thus the term encompasses a broad spectrum of chemicals and often, health risks arise from aggregate exposure to several different species. Because many EDCs act on the same hormone receptors on a cell's surface, researchers have been developing tests that detect the compounds based on their ability to interfere with hormones. But these methods currently take days to produce a result or involve many complicated and expensive steps. Here, Matthew Francis and colleagues overcame these challenges by using E. coli in their device.
Non-toxic, dead E. coli cells display an estrogen receptor on the surface of the researchers' portable sensor. A protein on the sensor surface recognizes the EDC-E. coli complex, producing an electronic read-out in minutes. The inexpensive device can determine the concentration of many known EDCs individually and overall concentrations as mixtures. They tested the detection in water and in complex solutions like baby formula. It also can detect EDCs released into liquid from a plastic baby bottle following microwave heating. The team notes that their test is suitable for use in the field and can be modified to test for other types of chemicals that act on human receptors.
The authors acknowledge funding from the HoundLabs, the National Science Foundation and the Beckman Foundation.
Watching water freeze (video)
ACS Omega
Every winter, snow and ice dusts mountains and makes roads slick in cold climates. This phenomenon is ages old, but a detailed explanation for how ice crystals form has eluded us. In a study appearing in the journal ACS Omega, scientists now report a method to visualize ice in three dimensions as it grows. This knowledge could have a range of potential uses in materials science, geophysics, biology and food engineering.
What scientists know for sure is that ice shape and size depend on a number of factors, such as pH, the speed at which the temperature drops and the composition of additives. They have tried controlling ice shape by adding a variety of compounds, including sugar, ethanol and naturally occurring anti-freeze proteins from fishes, plants and insects. But to gain a deeper understanding of how ice forms — and potentially to have better control over the process — scientists have been working on new ways to watch crystals grow in real time. Several methods have been attempted, but none have provided reliable 3-D visualizations. A team of scientists from the Ceramics Synthesis and Functionalization Lab in France took a different approach.
The researchers demonstrated that confocal laser scanning microscopy and image analysis can rapidly capture a series of pictures showing the ice crystals growing. The images can then be used to measure how fast the crystals expand and lengthen. The approach has promise for further studying ice growth under varying conditions and with the addition of polymers, proteins or other compounds, the researchers say.
The authors acknowledge funding from the European Research Council.
Watch ice crystals form in this video.