SOUTHWESTRETORT
SEVENTY-SEVENTH YEAR January 2025
Published for the advancement of Chemists, Chemical Engineers and Chemistry in this area published by
The Dallas-Fort Worth Section, with the cooperation of five other local sections of the American Chemical Society in the Southwest Region.
Vol. 77 (5) January 2025
Editorial and Business Offices: Contact the Editor for subscription and advertisement information.
Editor: Connie Hendrickson: retort@acsdfw.org
Copy and Layout Editor: Lance Hughes: hugla64@gmail.com
Business Manager: Martha Gilchrist: Martha.Gilchrist@tccd.edu
The Southwest Retort is published monthly, September through May, by the Dallas-Ft. Worth Section of the American Chemical Society, Inc., for the ACS Sections of the Southwest Region.
2024 ACS DFW Executive Committee
Chair: Rajani Srinivasan
Chair-elect: Denise Lynn Merkle
Past Chair: Michaela C. Stefan
Treasurer: Martha Gilchrist
Secretary: Trey Putnam
Councilors:
MaryAnderson
Kirby Drake
Linda SchultzR
Rebecca Weber
Alternate Councilors:
Michael Bigwood
Daniela Hutanu
Danny Tran
From the ACS Press Room
High-fat diet during adolescence increases impulsive behaviors in adult rodents
“From Nutritional Patterns to Behavior: High-Fat Diet Influences on Inhibitory Control, Brain Gene Expression, and Metabolomics in Rats"
ACS Chemical Neuroscience
For adults, a diet high in saturated fats and added sugar has been linked to impulsivity and poor self-control. But what role, if any, does diet play in adolescent psychological development? Researchers report in ACS Chemical Neuroscience that adolescent rodents fed a high-fat diet showed poor control during motor inhibition tasks and conservative decision-making in gambling scenarios as adults. This information could provide insights into human development.
Maslov Dmitry/Shutterstock.com
Diet is one of many factors like sleep, exercise and substance use expected to affect an adolescent’s cognitive development and reward-seeking behavior. Previously, re-
searchers collected evidence that supports the importance of sleep and exercise on behavioral development, but there is limited data about the effects of specific patterns of eating. So, Santiago Mora and colleagues designed experiments to look at the potential influences of a high-fat diet during adolescence on the actions and choices of adult rats.
For the experiments, Mora’s team fed 20 young rats a high-fat diet of cheesecake (cheesecake rats) and another 20 a nutritionally balanced chow diet (chow rats). When the rodents reached adulthood, the researchers trained all 40 to perform multiple tasks, including a gambling scenario. These attention and inhibitory-control tasks allowed the researchers to evaluate the animals’ abilities to manage impulsive and compulsive actions and make safe decisions. Task evaluations revealed that adult cheesecake rats prematurely responded to visual cues (i.e., jumping the gun to get a tasty snack), which the researchers say is evidence of increased impulsive actions. However, the adult cheesecake rats exhibited less risky decision-making by opting for safer but smaller rewards during gambling scenarios (i.e., no high rolling in casinos) than the adult chow rats.
In additional tests, the researchers identified genetic differences between the cheesecake and chow rats’ prefrontal cortices (one of the parts of the brain that control behavior and personality) and gut metabolism biomarkers.
Continued on page 12
Rats fed a high-fat diet of cheesecake demonstrated restraint during specially designed rodent gambling scenarios.
From the ACS Press Room
This prototype sunscreen protects your skin and cools you off, too
“High-Performance Radiative Cooling Sunscreen"
Nano Letters
Wearing sunscreen is important to protect your skin from the harmful effects of UV radiation but doesn’t cool people off. However, a new formula, described in ACS’ Nano Letters, protects against both UV light and heat from the sun using radiative cooling. The prototype sunblock kept human skin up to 11 degrees Fahrenheit (6 degrees Celsius) cooler than bare skin, or around 6 F (3 C) cooler than existing sunscreens.
Radiative cooling involves either reflecting or radiating heat away from something, cooling whatever’s underneath. It is already used to create cooling fabrics and coatings that could both cool and heat homes, among other applications. Some passive radiative cooling technologies rely on an ingredient called titanium dioxide (TiO2) because the whitish substance reflects heat. TiO2 particles are also used in mineral sunscreens to reflect UV light, but the particles aren’t the right size to produce a cooling effect. So, Rufan Zhang and colleagues wanted to tune the size of TiO2 nanoparticles to create a sunscreen that works both as a UV protector and a radiative cooler.
The team created their sunblock by combining six ingredients: TiO2 nanoparticles, water, ethanol, moisturizing cream, pigments, and a common silicone polymer used in cosmetics called polydimethylsiloxane. By carefully adjusting the sizes of the
TiO2 nanoparticles, they produced a material that reflects both UV light and solar heat, imparting the cooling ability. The new formulation demonstrated an SPF of about 50, water resistance and continued efficacy after 12 hours of simulated sunlight exposure with a xenon lamp. Additionally, when applied to both animal and human skin, the product didn’t cause irritation.
A new SPF 50 sunscreen prototype uses radiative cooling to both protect the skin from UV rays and cool it off. Compared to a commercial sunscreen, the new formula kept the skin cooler when measured under a thermal camera (blue area on right-hand image).
Adapted from Nano Letters 2024, DOI: 10.1021/ acs.nanolett.4c04969
In tests on people in a hot and humid outdoor environment, the new radiative cooling sunscreen was found to keep the participants’ skin up to 10.8 F (6.0 C) cooler than bare skin, and up to 11.0 F (6.1 C) cooler than commercially available sunscreens. The formulation is inexpensive, costing only $0.92 for 10 grams of the mixture on par with sunblocks already on the market. The researchers say their sunscreen prototype exhibits promising commercial potential, especially as temperatures in the summer continue to rise.
Continued on page 12
From the ACS Press Room
Elevated levels of ‘forever chemicals’ found in several smartwatch wrist bands
“Presence of Perfluorohexanoic Acid in Fluoroelastomer Watch Bands"
Environmental Science & Technology Letters
Smartwatches and fitness trackers have become ubiquitous forms of wearable tech, accompanying many people throughout their days (and nights). But they may expose the skin to so-called forever chemicals in the process. More expensive wristbands made from fluorinated synthetic rubber revealed particularly high amounts of one forever chemical, perfluorohexanoic acid (PFHxA), according to a study published in ACS’ Environmental Science & Technology Letters.
Some smartwatch bands, similar to those pictured here, have been found to contain the forever chemical perfluorohexanoic acid (PFHxA).
Umer Bajwa/Shutterstock.com
“This discovery stands out because of the very high concentrations of one type of forever chemical found in items that are in prolonged contact with our skin,” says Graham Peaslee, the corresponding author of the study.
Per- and polyfluoroalkyl substances (PFAS) are a group of chemicals that are very good at two things lasting seemingly forever in the environment and repelling water, sweat and oil. Because of the latter properties, manufacturers include these chemicals in many consumer products, such as stain-resistant bedding, menstrual products and fitness wear, including smartwatch and fitness tracker wristbands. The bands contain fluoroelastomers, synthetic rubbers made from chains of PFAS, to create a material that avoids discoloration and repels dirt. Though this durability makes the bands great for sweaty workouts, it might also present a source of these compounds to get under the wearer’s skin literally. So, Peaslee and co-authors Alyssa Wicks and Heather Whitehead investigated several commercially available watchbands for the presence of fluorine as well as 20 individual PFAS.
The team screened 22 wristbands from a range of brands and price points, most of them newly purchased but a few previously worn. All of the 13 bands advertised as being made from fluoroelastomers contained the element fluorine. But two of the nine bands that did not advertise being made from fluoroelastomers also contained fluorine, which indicates the potential presence of PFAS. Of those tested, wristbands that cost more than $30 contained more fluorine than those under $15. Next, following a chemical extraction, all the wristbands were checked for 20 different PFAS. PFHxA was found to be the most common, appearing in nine of 22 tested
Continued on page 12
From the ACS Press Room
Residents of unburned homes reported health symptoms months after Marshall Fire
“Physical Health Symptoms and Perceptions of Air Quality among Residents of Smoke-Damaged Homes from a Wildland Urban Interface Fire"
ACS ES&T Air
Wildfires that burn homes and vehicles could expose people to dangerous airborne compounds through ash and smoke. Research published in ACS ES&T Air has shown that people returning to their unburned homes may also experience health symptoms months after a nearby fire is extinguished. Through a survey of people affected by the 2021 Marshall Fire in Boulder, Colorado, researchers found that headaches, sore throats and coughs were frequently self -reported by residents living near burned structures.
Wildland-urban interface fires, like the Marshall Fire and the fires in early 2025 across Los Angeles, burn both natural vegetation and human-made materials. Polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) are emitted at higher levels from human-made materials than natural biomass when burned. Exposure to these airborne compounds has been linked to negative health outcomes, including lung and cardiovascular diseases, according to the World Health Organization. After the Marshall Fire, researchers from the nearby University of Colorado, Boulder, found elevated levels of PAHs and VOCs in unburnt homes damaged by smoke, but they didn’t investigate what negative health out-
comes might have been caused by exposure to these compounds. So, another CU Boulder team, led by Colleen Reid, designed and launched a survey to understand the potential symptoms experienced by residents.
The 2021 Marshall Fire destroyed more than 1,000 homes, and residents living in homes left standing reported health effects months after the fire.
Kent Raney/Shutterstock.com
The survey was conducted twice, once at 6 months after the fire (642 respondents) and again at 1 year (413 respondents), among participants whose homes remained intact. The researchers asked participants about post -fire smoke impacts and health symptoms. They found that:
• · The most common fire-related symptoms were itchy or watery eyes, headaches, dry coughs, sneezing and sore throats.
• · 61% of respondents reported campfireor chemical-like smells in their homes 1 week after the fire, but those smells dissipated over time.
From the ACS Press Room
• · 65% of respondents reported ash in their homes post-fire.
• · Most respondents were less confident in the air quality of their home and neighborhood 6 months post-fire than pre-fire, but most of that confidence was restored by the 1-year mark.
The team found that many self-reported symptoms (headaches, strange taste in the mouth) clustered together for residents whose homes were within 250 meters of a burned structure. In addition, dry coughs, itchy/watery eyes and sneezing were statistically associated with a change in the home’s smell post-fire and/or finding smoke damage or ash inside. In fact, respondents who found visible ash in their home were over three times more likely to report headaches than people who didn’t. Many participants said that cleaning their homes or HVAC systems, hiring cleaning companies, or replacing affected furniture or carpets helped reduce the smell over time. Researchers hope their findings will inform future regulations and guidelines on how to return home safely after a wildfire.
The authors acknowledge funding from the National Science Foundation, the Cooperative Institute for Research in Environmental Sciences (CIRES) Rapid Innovation Research Program at the University of Colorado, Boulder, the Harvard JPB Environmental Health Fellowship, and the Developmental Core of the University of Colorado Population Center.
From the ACS Press Room
Potentially harmful bacteria slip through antimicrobial showerheads
“Not the Silver Bullet: Uncovering the Unexpected Limited Impacts of SilverContaining Showerheads on the Drinking Water Microbiome"
ACS ES&T Water
To guard against harmful waterborne pathogens, many consumers, including managers of health-care facilities, install antimicrobial silver-containing showerheads. But in ACS ES&T Water, researchers now report that these fixtures are no “silver bullet.” In realworld showering conditions, most microbes aren’t exposed to the silver long enough to be killed. However, the composition of rare microbes in water from these showerheads varied with each type of fixture tested.
The stream of droplets and fine mist that form during a shower could be inhaled or swallowed. Installing showerheads containing silver a naturally antimicrobial metal is a cost-effective way to potentially protect against drinking water-associated pathogens (DWPIs). DWPIs, such as the strains Pseudomonas and Legionella, can cause infections in people with compromised immune systems. However, researchers have previously reported that reducing DWPI by adding copper and silver to a building’s water system to eliminate bacteria and viruses (i.e., copper-silver ionization) is a temporary or minor fix. The copper-silver ionization study results have raised concerns in the scientific community that short-term silver exposure in showerheads could fortify microbes instead and increase the risk of antimicrobial resistance, rather than curb it. So, Sarah-Jane
Haig and colleagues wanted to see how showerheads containing silver affected the microbial composition of the water.
The team compared two conventional showerheads made of either plastic or metal with three fixtures that contained silver as a silver mesh within the showerhead, a silvercoated copper mesh in the showerhead and hose, or as a silver-embedded polymer composite. The showerheads were run in Haig’s full-scale shower lab facility, which was developed to mimic real-world conditions.
Contrary to the antimicrobial claims of manufacturers, silver did not reduce overall DWPI concentrations or total bacteria in water samples in the researchers’ shower lab. Haig and her team reasoned that this is a result of differences in their testing conditions versus those of the manufacturers’. More specifically, in this study the water came out of the showerhead in a quick rush, as would happen when someone takes a shower. However, the
Continued on page 13
Antimicrobial, silver-contained showerheads do little to stop waterborne microbes.
DG Fotostock/Shutterstock.com
Videos
Can kidney stones be prevented by drinking citrus juice?
WASHINGTON, Nov. 11, 2024
Kidney stones are the worst, so Reactions host Alex Dainis made some at home and tested supposed prevention methods to keep them at bay. Doctors recommend citrate to ward them off, but how is a little lemon in your water going to stop them from forming? And are all citrus juices the same, or does orange juice prevent kidney stones more than lemon juice or even grapefruit juice? This week Alex gets the answers.
Youtube ID: V16si8taEqQ
Reactions is a video series produced by the American Chemical Society and PBS Digital Studios. Subscribe to Reactions and follow us on X, formerly Twitter @ACSReactions.
Is it true that trees pollute the air?
WASHINGTON, Oct. 28, 2024 Methane is the most famous volatile organic compound (VOC) in our atmosphere. This week, our host George Zaidan follows up on a Reactions subscriber’s question about the 600 teragrams of a less famous VOC released every year: isoprene. Used in the biosynthesis of a staggering number of molecules, isoprene is also released from plants, including many species of trees. And
they release exponentially more isoprene as the temperatures climb. In large cities, isoprene can react with nitrogen oxides from fossil-fuel combustion to create ground-level ozone. Join George as he explores whether this should change how we think about trees.
YoutubeID: kYcd5QK5o3E
Reactions is a video series produced by the American Chemical Society and PBS Digital Studios. Subscribe to Reactions and follow us on X, formerly Twitter @ACSReactions.
“Chiral Synthesis”
WASHINGTON, June 17, 2024 L-DOPA is the best drug we have for Parkinson’s disease, but its molecular mirror image, DDOPA, causes dangerous side effects. Making L-DOPA without also making D-DOPA is surprisingly hard and requires a specific kind of molecule to pull off. But that specific molecule must be made from a different and equally specific molecule. In this video, our host, George Zaidan, explains how one of the winners of the 2001 Nobel Prize in Chemistry pulled it off, and why "chiral synthesis," as it's called, is really just turtles all the way down.
https://youtu.be/ _cb09XB07LQ? si=BuMEI5fOuHmuQlkZ
From the ACS Press Room
continued
High fat diet
Continued from page 5
Briefly, the cheesecake rats exhibited altered function of the mesolimbic pathway the so -called reward pathway in their brains and had modified levels of fatty acids in their guts linked to neurological and behavioral outcomes. The results suggest that a high-fat diet during adolescence could interfere with brain development and affect neurobehavioral outcomes in adulthood.
The researchers say that their data show a high-fat diet in adolescence can provoke longterm changes in impulsive behavior in rats, but they recognize more research is needed to “disentangle the specific mechanisms underlying these intriguing effects.”
The authors acknowledge funding from the European Regional Development Fund (Fondo Europeo de Desarrollo Regional) and Ministry of Health, Government of Spain (Ministerio de Sanidad, Gobierno de España). The authors acknowledge the use of generative AI in their scientific writing.
This prototype sunscreen protects your skin
Continued from page 6
The authors acknowledge funding from the National Key Research Program, the National Natural Science Foundation of China and the Tsinghua-Toyota Joint Research Fund.
Elevated levels of ‘forever chemicals’
Continued from page 7
wristbands. The median PFHxA concentration was found to be nearly 800 parts per billion (ppb), and one sample exceeded 16,000 ppb. Comparatively, previous research by the team in 2023 on cosmetics found a median concentration of around 200 ppb of PFAS. Currently, only six PFAS have federally defined exposure limits for drinking water in the U.S.; exposure limits for other PFAS and other exposure routes are still being studied.
“We have never seen extractable concentrations in the part-per-million range (>1000 ppb) for any wearable consumer product applied to the skin,” says Peaslee.
The researchers suggest that the large amounts of PFHxA found in the wristbands may be a result of the compound being used as a surfactant during the fluoroelastomer manufacturing process. Scientists do not currently understand how readily PFHxA transfers into the skin, nor the potential
From the ACS Press Room
continued
health effects it poses once it gets there, though Peaslee says recent studies suggest that a significant percentage could pass through human skin under normal conditions.
Wicks, the study’s lead author, says the team recommends purchasing lower-cost wristbands made from silicone. “If the consumer wishes to purchase a higher-priced band, we suggest that they read the product descriptions and avoid any that are listed as containing fluoroelastomers.”
The authors acknowledge funding from the University of Notre Dame.
Potentially harmful bacteria
Continued from page 10
standard tests used by manufacturers expose microbe cultures to the silver material alone for 16 to 24 hours, which the team says is not an appropriate timeframe or a realistic scenario.
Although the overall pathogen concentration in the water samples didn’t vary between standard and silver showerheads, the composition of the microbiome did. The populations were different for each of the silvercontaining fixtures, which suggests that the way the silver was incorporated into the showerheads mattered, and rare microbes accounted for most of the differences. Further experiments by the team suggest that microbes in the silver-containing showerheads could be more prone to forming microbial communities called biofilms in response to the stressful environment. In addition, biofilms might explain the association between the number of different species and showerhead age, say the researchers, because these communities are reservoirs for DWPIs.
“These findings underscore the need for improved testing standards, real-world performance evaluation, and innovative solutions to mitigate microbial risks in water systems, benefiting consumers and vulnerable populations,” says Haig.
The authors acknowledge funding from the National Science Foundation.
From the Editor
January is always a pretty slow month, so we’re always a little short on material at this time. Schools are closed for winter break, there’s a little vaycay time, and this year there were snow and ice days.
An interesting thing happened over the holiday season, though: “The US Food and Drug Administration has banned the use of red dye No. 3 in food, beverages and ingested drugs, more than 30 years after scientists discovered links to cancer in animals, the agency announced Wednesday.” It has been banned in topical drugs and cosmetics since 1990.
Here’s the link:
https://www.cnn.com/2025/01/15/health/red-dye-no-3-ban-fda-wellness/ index.html
Have a good start to the year!
