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Protein-Rich Microalgae Can Grow at the High CO2 Levels in Industrial Exhaust

Our world’s population is growing fast—and with it, our demand for not only meat but also animal feed. Soy is a common protein supplement in animal feed, but growing soybeans requires fresh water, fertilizer, and vast swaths of land. Protein-rich microalgae need less of these resources, and a new study shows that they can grow at the carbon dioxide levels found in exhaust from coal-fired power plants, oil refineries, and other industrial processes. The results show that microalgae have the potential to be a more sustainable alternative to soy in animal feed, the researchers say.

Earlier studies had reported that the CO2 concentrations in industrial emissions were too high for microalgae to consume as an energy source and could inhibit their growth. Some researchers proposed that pH changes in the solution in which the microalgae grow, caused by increased CO2 concentrations, are to blame. CO2 dissolves in solution to become carbonic acid, which deprotonates, making the solution acidic and lowering pH levels. As a result, high CO2 concentrations can make the solution too acidic for microalgae to grow. Researchers have tried to maintain constant pH levels through methods such as periodically adding ammonium salts or using higher concentrations of buffer, and then letting the pH gradually change.

Jerald L. Schnoor of the University of Iowa and Hannah R. Molitor, a graduate student in his laboratory, grew microalgae in bioreactors that enabled far more precise pH control. They chose the species Scenedesmus obliquus, since it’s highly nutritious, grows fast, and has qualities that make it more likely to thrive on wastewater, such as its football-like shape, which a previous study had suggested could help it resist shear forces in a wastewater stream. Continuous feedback from the bioreactor’s pH meter controlled the addition of a base to freshwater algae medium to maintain a constant pH of 6.8, which falls within the optimal pH range for S. obliquus growth.

The researchers grew S. obliquus at several different CO2 concentrations, ranging from atmospheric levels to the higher levels found in industrial emissions. At each CO2 concentration, they measured the optical density of S. obliquus samples taken over time and used mathematical modeling to calculate the maximum growth rate.

Previous studies had measured the highest maximum S. obliquus growth rate at 2.5% CO2, but Schnoor and colleagues measured it at 4.1% CO2, and their model predicted that maximum growth would occur at 4.5% CO2 in the real world. In fact, S. obliquus didn’t show inhibited growth until 10% CO2—higher than the levels in natural gas combustion and oil refining emissions—and grew well even at up to 35% CO2—higher than the levels in cement manufacturing emissions. These results suggested that the CO2 levels in industrial emissions are not a barrier to microalgae growth.

The researchers also compared the amino acid profiles of S. obliquus and soy. Farmers often have to supplement soy-containing cattle feed with methionine, but since the microalgae contained twice as much methionine as soy, they may not need to do that with microalgae-containing cattle feed, Molitor says.

Fengqi You, a chemical and biomolecular engineer at Cornell University, calls the findings “promising.” Growing microalgae for animal feed would not only remove planet-warming CO2 from industrial emissions but also watershed-polluting nitrate from wastewater, which is also consumed by microalgae, he says.

But You also points out that the Iowa researchers conducted the study at benchtop scales under highly controlled laboratory conditions. Indeed, they didn’t grow S. obliquus on wastewater nor use actual industrial emissions samples, which would contain pollutants that may inhibit S. obliquus growth or have toxic effects on it. Although Molitor says their model’s prediction of the optimal CO2 concentration for S. obliquus would likely hold up at industrial scales, they can’t say for certain until pilot studies validate their findings. The economic feasibility of growing microalgae near sources of industrial emissions also remains unclear, You adds.

Still, the study is “a nice proof of concept,” he says. If its findings do hold up at industrial scales, “it could lead to a huge change to nationwide or global food systems.”

This article is reproduced with permission from C&EN (© American Chemical Society). The article was first published on May 21, 2019.

ACS Editors’ Choice: Physical Chemistry of Epigenetics — and More!

This week: the physical chemistry of epigenetics — and more!

Each and every day, ACS grants free access to a new peer-reviewed research article from one of the Society’s journals. These articles are specially chosen by a team of scientific editors of ACS journals from around the world to highlight the transformative power of chemistry. Access to these articles will remain open to all as a public service.

Check out this week’s picks!
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Physical Chemistry of Epigenetics: Single-Molecule Investigations

J. Phys. Chem. B, 2019, XXXXXXXXXX-XXX
DOI: 10.1021/acs.jpcb.9b06214
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Platinum/Graphene Oxide Coated Microfabricated Arrays for Multinucleus Neural Activities Detection in the Rat Models of Parkinson’s Disease Treated by Apomorphine

ACS Appl. Bio Mater., 2019, XXXXXXXXXX-XXX
DOI: 10.1021/acsabm.9b00541
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Realizing High Thermoelectric Performance in Polycrystalline SnSe via Silver Doping and Germanium Alloying

ACS Appl. Energy Mater., 2019, XXXXXXXXXX-XXX
DOI: 10.1021/acsaem.9b01475
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Processing Pathways Decide Polymer Properties at the Molecular Level

Macromolecules, 2019, XXXXXXXXXX-XXX
DOI: 10.1021/acs.macromol.9b01195
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Technical Synthesis of 1,5,9-Cyclododecatriene Revisited: Surprising Byproducts from a Venerable Industrial Process

J. Org. Chem., 2019, XXXXXXXXXX-XXX
DOI: 10.1021/acs.joc.9b01633
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Engineered Enzymes and Bioinspired Catalysts for Energy Conversion

ACS Energy Lett., 2019, 4XXX2168-2180
DOI: 10.1021/acsenergylett.9b01308
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Electronic Communication as a Transferable Property of Molecular Bridges?

J. Phys. Chem. A, 2019, XXXXXXXXXX-XXX
DOI: 10.1021/acs.jpca.9b05618
***
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CAS Future Leaders Blaze a Trail Toward Scientific Leadership

Celebrating its 10th year, the CAS Future Leaders Program awards early-career scientists with essential scientific, business, and leadership training, and a trip to the ACS National Meeting & Exposition. This year participants took part in programming related to five leadership themes.

Storytelling

Great narratives can generate interest and engagement with a topic, improve comprehension, and influence real-world beliefs. Participants learned the essential leadership skill of storytelling and presented their research stories in a poster session attended by a diverse group of scientists, technologists, marketers, and administrators who work for CAS and ACS Publications.

Insights

Successful leaders are results oriented. Whether they need to deliver published manuscripts, funded grants, or completed projects, having deep insights into the research process can help them succeed at every step. Participants explored the process by which research is published, indexed, and delivered to scientists around the world, and went behind the scenes to see how SciFindern. can help them quickly find actionable results and deliver on their next big research project.

Strategies

Collaboration is essential to scientific progress. Successful leaders inspire the best performance from their collaborators, research teams, and others by using several coaching techniques, such as building trust, clarifying their vision, and respectfully challenging and celebrating success. During an interactive workshop, participants learned science-based coaching strategies to help them lead highperforming teams and productive collaborations.

Perspectives

Scientists must drive understanding of their research not only in the published literature but also among science-policy makers, the media, industry stakeholders, and funding organizations. Successful leaders adapt their communication style for their audience and have a broad understanding of the scientific enterprise as a whole. An array of science-industry thought leaders shared their perspectives to inspire participants to make meaningful impacts in the lab and beyond.

Impacts

Research matters. Whether it leads to innovation in health care or technology, or supports a greener Earth, it’s important that leaders recognize the impacts of their research and strive for real-world solutions. Participants visited with physicians, researchers, and
cancer survivors at The Ohio State University Comprehensive Cancer Center – James, one of only 50 NCI designated comprehensive cancer centers in the nation.

Are you a Ph.D. student or postdoctoral researcher who would like to blaze a trail toward scientific leadership? Learn more at www.cas.org/futureleaders.

Turning Pollen into a Tool for Fighting Pollution

Pollens and spores can be used to create particles used to remove pollutants from water, say researchers from University of Hull. The resulting particles can prevent contaminants from agricultural field runoff from ending up in the water supply. They may also have uses in the pharmaceutical and cosmetics industries. Best of all, these refined particles don’t trigger allergies.

Watch a short video explaining the method:

Watch Aimilia Meichanetzoglou of University of Hull describe her work at the ACS Fall 2019 National Meeting & Exposition in San Diego:

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Prototype Diagnostic Patch Picks Up on a Chemical Below the Skin

One day doctors might replace some blood tests with a small microneedle skin patch followed by a quick scan of the sample. As a step toward that goal, researchers have demonstrated a simple prototype device that combines microneedles and sensor-laden paper to sample fluid from below the skin. The researchers can directly detect a dye infused into rats by collecting interstitial fluid with the device and analyzing it with surface-enhanced Raman spectroscopy (SERS).

Mark R. Prausnitz and his colleagues at the Georgia Institute of Technology have been studying the idea of using arrays of tiny needles to deliver drugs and vaccines below the skin’s surface, avoiding both uncomfortable injections and hypodermic needle waste. Recently they have extended this work toward developing microneedles that can sample interstitial fluid —the clear, nonclotting liquid that the body’s cells bathe in—to do diagnostics. But extracting and analyzing chemicals from this fluid can be complicated and inconvenient. These steps dilute the sample and can lead to analyte loss.

While at Georgia Tech as a graduate student, Chandana Kolluru wondered if they could make a simple device that skips the extraction steps. She read about plasmonic paper developed by Srikanth Singamaneni of Washington University in St. Louis, for embedding nanoparticles into paper, which boosts the Raman signal from adhered molecules. Singamaneni’s team has detected trace amounts of molecules as diverse as explosives with SERS and cancer biomarkers with localized surface plasmon resonance.

Kolluru contacted Singamaneni and soon the teams were collaborating, marrying microneedles with plasmonic paper. “Can we integrate some kind of sensing element into the paper so we can do the analysis directly on the paper?” Singamaneni asks.

As a proof-of-concept, they built a device for detecting rhodamine 6G, a positively charged fluorescent dye, that they administered to rats. First, they grew gold nanoparticles and coated them with negatively charged poly(4-styrenesulfonic acid). Then they concentrated the coated nanoparticles into an ink and placed it in a ballpoint pen cartridge. They wrote the ink onto a 1 mm by 7 mm strip of filter paper and attached it to a strip of nine steel microneedles 650 µm long.

To collect interstitial fluid, researchers applied patches to six hairless rats who had been infused with 10 mg/mL of the dye for 30 min. They allowed the paper sensor strip to become saturated and successfully detected the dye in the collected fluid using SERS. Handheld SERS instruments are now available, which means such tests could be done outside a laboratory.

Other groups have used microneedle devices to directly detect glucose or optically detect drugs, says Ronen Polsky of Sandia National Laboratories, who was not involved in the research. But it’s the first time that researchers have combined interstitial fluid extraction with microneedles and SERS detection. If the team can demonstrate that the paper-backed microneedles can detect a drug or biomarker using SERS, he adds, such a device would be “extremely valuable.”

Singamaneni agrees that a major challenge will be functionalizing the nanoparticles with antigens that bind specifically to biomarker targets. In addition, researchers need more information about how biomarker concentrations in interstitial fluid correlate with levels in blood, he says. “Most diagnostics are based on blood,” he says. “We need a better understanding of what’s going on in interstitial fluid.” Prausnitz is the founder of microneedle company Micron Biomedical. His Georgia Tech team is continuing to work toward a human diagnostic, Kolluru says.

This article is reproduced with permission from C&EN (© American Chemical Society). The article was first published on May 24, 2019.

Using Cell Phones as Norovirus Detectors

Norovirus causes about 20 million cases of food poisoning in the U.S. every year. The virus might be best known for infamous outbreaks on cruise ships, ruining vacations with severe vomiting, diarrhea, and stomach pain. But the highly infectious virus can also strike closer to home, with water- and foodborne outbreaks occurring in municipal water systems, schools and restaurants. Today, researchers from the University of Arizona are working on an easy, inexpensive, and extremely sensitive way to detect norovirus using a cell phone and mostly off-the-shelf parts. The device could be deployed on cruise ships and other areas where labs are inaccessible.

Watch a short video explaining the method:

Watch Jeong-Yeol Yoon of University of Arizona describe his work at the ACS Fall 2019 National Meeting & Exposition in San Diego:

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Baby Teeth Reveal Children’s Past Lead Exposure

Lead is a potent neurotoxic element with no known safe level, but proving past exposure to lead has been a challenge: blood tests only show exposure someone has experienced within the past 4 weeks. Now, researchers have used lost baby teeth to measure lead levels from children who lived near a polluting battery recycling plant.

In an urban patch of Los Angeles, the Exide Technologies plant processed 11 million car batteries per year, emitting lead and arsenic from its smokestacks on the people who lived in the area until it shut down in March 2015. Residents wanted to know what they had been unwittingly exposed to. Community volunteers gathered 50 baby teeth that had been saved from 43 kids (age 7-18, with a median age of 12) who had lived within a 3.2 km radius of the smelter for their entire lives. The residential communities nearby are more than 90% Latino and rank among the top 10% of the most environmentally burdened neighborhoods in California, according to an analysis by the state.

Jill E. Johnston, an environmental health researcher at the University of Southern California, had been talking with the people who lived near this plant and also knew about work by Manish Arora, an environmental scientist and dentist at the Icahn School of Medicine at Mount Sinai. Arora had used laser ablation and inductively coupled plasma mass spectrometry to analyze trace elements within baby teeth in past studies. Baby teeth start forming in utero and incorporate minerals into layers of dentin and enamel as they develop, like rings on a tree. Johnston thought the same method would work in this situation to measure lead and arsenic. “This was a way to get a better sense of what past exposure looked like,” she says.

The researchers used a focused laser beam to blast material off the surface of the tooth samples for mass spectral analysis, peeling back the layers to look back in time at what they contained. They were able to determine the neonatal line, a band of growth lines that delineate the baby’s birth, and other time-based features in the teeth.

They compared the prenatal and postnatal lead and arsenic concentrations in the teeth with current known levels of lead in the soil of the homes where these children lived, and found that prenatal tooth lead levels increased as soil lead levels increased. Fifteen of the 43 children also had arsenic in their teeth both before and after birth.

Hernán F. Gómez, a medical toxicologist at the University of Michigan who analyzed the blood lead levels of children in Flint, Michigan, says the research was a well-planned and well-executed way to examine an important potent neurotoxic element that has afflicted the very young for centuries. “The authors are to be complimented for their approach in using deciduous teeth to examine prenatal and postnatal exposure to lead in an at-risk, post-industrial setting,” he says.

Johnston says this initial research was a pilot study, and she hopes to analyze more teeth from a wider area around the plant in the future. “It’s important to generate and share data so people can learn more about what the exposures may have been,” she says. “We are hoping we can push more transparency by giving data back to the community.”

This article is reproduced with permission from C&EN (© American Chemical Society). The article was first published on May 29, 2019.

Researchers Fight Ticks By Targeting Their Salivary Glands

Saliva from a tick’s bite can transmit pathogens that cause serious illnesses, such as Lyme disease. They can also lead to significant agricultural losses. Current insecticides have drawbacks, so scientists have been seeking new ways to prevent these pesky arachnids from spreading pathogens. Researchers at Louisiana State University are working on a way to kill ticks by targeting their salivary glands, noting that saliva plays a number of key roles in a tick’s ability to drink blood. Using a potassium channel inhibitor they developed, researchers were able to make the ticks produce less saliva. The ticks subsequently drank dramatically less blood and then died within 12 hours, which prevents ticks from transmitting pathogens, such as Lyme disease.

Watch a short video explaining how the method works:

Watch Daniel Swale of Louisiana State University describe his work at the ACS Fall 2019 National Meeting & Exposition in San Diego:

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New Electrochemical Method Detects PFOS and PFOA

Bubbles and tiny electrodes may hold the key to faster, more cost-effective detection of perfluorinated surfactants that can contaminate drinking water. Researchers have developed an electrochemistry-based method to detect surfactants, specifically perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), with high sensitivity and specificity.

Perfluorinated surfactants are highly stable due to perfluoroalkyl moieties, and are common in products like nonstick coatings and fire-fighting foam. Chronic exposure to two such perfluoroalkyl substances, PFOS and PFOA, has been linked to health issues in humans. Though these two chemicals are no longer used in industry, they persist in the environment and can contaminate drinking water.

Long Luo, an analytical chemist at Wayne State University, began his search for a novel way to detect these harmful chemicals after one such PFOS/PFOA contamination event in a Michigan town during the summer of 2018. The most commonly used detection method uses high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), which requires complex instrumentation and can cost up to $300 per sample, Luo says. Hoping to develop a simpler, less expensive method, the team turned to electrochemistry.

Their method is based on a phenomenon known as electrochemical bubble nucleation. Applying electric potential to an electrode in an aqueous solution splits water into hydrogen gas and oxygen. Ramping up the current increases gas concentration near the electrode until a bubble forms, blocking the electrode surface and causing the current to drop. Surfactants reduce surface tension and make it easier for such bubbles to form, meaning the amount of current required to form those bubbles is inversely related to surfactant concentration.

To test their method, Luo and his collaborators fabricated tiny platinum electrodes less than 100 nm in diameter (smaller electrodes are more sensitive). The team could detect PFOS and PFOA concentrations as low as 80 µg/L and 30 µg/L, respectively. Preconcentrating samples using solid-phase extraction moved the limit of detection below 70 ng/L—the health advisory level for drinking water set by the U.S. Environmental Protection Agency. The method also remained sensitive and selective for surfactant detection even in the presence of a 1,000-fold greater concentration of poly(ethylene glycol), a nonsurfactant molecule with a molecular weight similar to that of PFOS.

“Electrochemical methods, in general, have great promise for measuring very low concentrations of contaminants in complex matrices,” says Michelle Crimi, an environmental engineer at Clarkson University. “I look forward to hearing more about the future of this technology, including its validation in field-contaminated water samples.”

Creating a handheld device for testing water in streams and other field sites—not just drinking water—is the ultimate goal, Luo says. An important step in that process will be developing a pretreatment phase to eliminate other surfactants that also promote bubble formation at electrodes, like sodium dodecyl sulfate. Such interference would be unlikely in drinking water samples, Luo says, because most compounds are not as stable as perfluoroalkyl substances and are destroyed during water treatment processing.

This article is reproduced with permission from C&EN (© American Chemical Society). The article was first published on May 13, 2019.

New Polymer Can Self-Destruct When the Job is Done

Researchers at the Georgia Institute of Technology have developed new polymers that are sturdy enough to deliver packages or sensors into hostile territory — and then break down once the military mission is complete.
The material has been made into a rigid-winged glider and a nylon-like parachute fabric for airborne delivery across distances of a hundred miles or more. It could also be used someday in building materials or environmental sensors.
The polymers have to be synthesized at low temperatures because they’re unstable at room temperature — though they can last for years are room temperature unless it is triggered. The polymer is designed to be triggered to dissolve in response to a thermal spike or a certain amount of exposure to ultraviolet light, such as in sunlight. The triggering mechanism can be adjusted to make the polymer useful in a variety of environments.

Watch a short video of the material in action:

Watch of Paul A. Kohl of the Georgia Institute of Technology describe this work at the ACS Fall 2019 National Meeting & Exposition in San Diego:

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