SOUTHWEST RETORT
SEVENTY-SIXTH YEAR
December 2023
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. 76(4) December 2023 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.
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TABLE OF CONTENTS ARTICLES and COLUMNS Letter from the Editor…..…..……..............17 And Another Thing…………………...……..6 NEWS SHORTS Swapping blood for spit — for convenient at -home health monitoring……………..…….5 Slippery toilet bowl treatment causes bacteria to slide right off ……………...……..…..8 Plastic-eating bacteria turn waste into useful starting materials for other products….......7 Sunflower extract fights fungi to keep blueberries fresh………………………………....8 Mixing heat with hair styling products may be bad for your health……………………...9 Recent advances in tree nut research — walnuts, pecans and more..……..…………….10 Blasts to clear World War II munitions could contaminate the ocean……………..12 Indoor solar’ to power the Internet of Things……………………………………...13 AROUND THE AREA UT Dallas
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From the ACS Press Room Swapping blood for spit — for convenient at-home health monitoring “Electrochemical Aptamer-Based Biosensors for Measurements in Undiluted Human Saliva” ACS Sensors
Blood tests are a common, yet often painful, step in health care. But what if we could skip the needles altogether? Saliva and blood contain many of the same biomarkers, and collecting spit is as simple as drooling into a container. Researchers reporting in ACS Sensors have developed a device that detects glucose and adenosine monophosphate (AMP) biomarkers in saliva with high sensitivity, which could help make at-home health monitoring easier and without a poke.
of device has previously been used on blood samples, but this time, Philippe DauphinDucharme and colleagues adapted E-AB biosensors for saliva samples. The team wanted to measure the concentration of glucose and AMP — a small molecule biomarker associated with gum disease — in real saliva specimens.
The team took previously reported DNA apBlood tests provide critical information tamers Saliva could one day replace blood to monitor about a person’s health. But they also rely on people’s health through indicators such as gluthat uncomfortable procedures, ranging from colcose levels. bound lecting small blood samples through frequent to ei- Girts Ragelis/Shutterstock.com finger pricks to blood draws from a trained ther AMP or glucose, then re-engineered phlebotomist. Saliva has been explored as an them to improve their sensitivity. They creatalternative way to track important bied their E-AB biosensors by mounting the omarkers, including glucose. However, most aptamers on a gold electrode. Saliva samples methods for analyzing saliva samples for were collected from a group of participants small molecules require laboratory equipand pooled together. The sensors were then ment. To make the analyses convenient for at immersed in the saliva, with no additional -home testing, a simple, yet accurate, sensing preparation steps or reagents needed. This platform is needed. One possibility is the simplicity makes the test easy enough to be electrochemical aptamer-based (E-AB) bioperformed by a patient in their home. In exsensor, which produces a measurable, elecperiments, the researchers found that their trochemical change when a specially dedevices returned a result within 30 seconds, signed piece of DNA or RNA, known as an Continued on page 15 aptamer, binds to its desired target. This type December 2023
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And Another Thing...: Demo by: Denise Lynn Merkle, PhD 12/6/2023 We're now more than a month past National Chemistry Week, headed into finals, end-of-year tasks, holidays, and (for some) a winter break, and it seems like a good time to chat about chemistry demonstrations. A recent poll* to ask about favorite chemistry demos yielded surprising (and occasionally hilarious) results. Thing 1: In case you were unsure of their effect, Chemistry Demonstrations are responsible for many students' interest in chemistry and their desire to go into chemistry or other science. Demos may feel like a slog to those who present them, over and over and over, but they work! Thing 2: While some poll respondents related repeatable, favorite demos, such as Dr. Kayla Green's gummi dinosaur extinction demo, described in a previous SW Retort**, which was catastrophic only to the candy, and a greatly appreciated titration in freshman chemistry at University of California Berkeley that turned from Stanford Red to Cal Bears Blue and Gold, many respondents cited the inspiration of demonstrations that unexpectedly became much more exciting than the presenter intended. For example:
An insect pheromone demo, designed to cause localized clustering of moths around a puddle of attractive hormone, which clearly showed that the released insects (perhaps wisely) valued their freedom much more than the potential for inter-moth interaction. The experiment's conclusion that a moth invasion results in the dismissal of class was secondary but did reinforce the crucial scientific principal that conclusions are based on actual data, not intended results. A Boomer demo that generated much more H2(g) than anticipated and made a significant impression on all who witnessed it - and also cleared the room (more rapidly than did the moths). A demonstration accurately named 'Chemical Rotten Eggs', that worked as expected by the happy chemist - but definitely did not have the same outcome for others in the building (or who had been in the building). Thing 3: There's much gratification in demos gone right and a significant overlay of glee when they go wrong. Demos gone wild have brought many scientists into the fold. That being said, Unintended Issues are definitively not the goal and are to be avoided. A Focus on Safety is incumbent on every single scientist, every single minute, every single experiment, every single demonstration. Whether in school, at work, at the kitchen island, out in
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the garage, in a field far from civilization - anywhere - acting in a safe and controlled way, with contingency plans in place, is the only way to Chem. Attendees of Kirk Hunter's recent safety presentation know that avoiding chemical errors while being ready to act in a crisis is key. https://institute.acs.org/acs-center/lab-safety.html Which brings us to Thing 4: If we're not going to accidentally release moths, clear buildings, dissolve desks, or spangle nascent scientists with glitter, how in the world will we bring them into the excitement of experiments gone right? How will we encourage them to dive into the scintillating beaker that is a life in chemistry? Demonstrations like Gummi dinos and school-spirited titrations will have to carry the torch (but far away from the flammables cabinet). * Interestingly, pretty much every respondent requested anonymity. ** October, 2023 "The Southwest Retort, newsletter of the DFW Local Section of the ACS". You read Dr. Green's interview, didn't you? didn't you? Read your Retort, chemists!
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From the ACS Press Room Slippery toilet bowl treatment causes bacteria to slide right off “Mechanochemical Activation of Silicone for Large-Scale Fabrication of AntiBiofouling Liquid-like Surfaces” ACS Applied Materials & Interfaces When entering public restrooms, it’s hard not to dwell on what germs previous users have left behind in the toilet bowl. Imagine, instead, a self-cleaning system that doesn’t require a brightly colored gel. Researchers reporting in ACS Applied Materials & Interfaces have developed a simple, transparent coating that makes surfaces, like porcelain, more water-repellent. They show how this surface treatment effectively prevents bacteria from sticking to the inside of a toilet bowl. Coatings can be applied to glass and porcelain to ensure water droplets easiAn easy-to-apply polymer coating ly slide off, made the toilet bowl on the left more preventing slippery than the untreated one on the fog or bacterial films from right. Adapted from ACS Applied Materials developing, & Interfaces 2023, DOI: 10.1021/ for example. acsami.3c11352 To add this water-repellant property to surfaces, scientists typically engineer microscopic structures, like the tiny barbs and hooks on bird feathers, to trap air or oils between the surface and water droplets. But this approach is typically labor intensive and can change the appearance of the surface. Another approach is to graft slippery polymer chains onto a December 2023
surface, and those polymers act like a permanent oil slick. However, this technique can involve harsh chemicals and isn’t feasible for use on everyday items. So, Mustafa Serdar Onses and coworkers wanted to find a more practical way to make polymer-grafted surfaces repel water and impede growth of bacterial films. Their selected approach involved grinding poly(dimethylsiloxane) (PDMS), a silicone oil, in a ball mill for an hour. In the mill, small tungsten carbide balls bombarded the oil at high speeds, breaking apart some of the polymer’s chemical bonds and forming new molecules. The team hypothesized that the milled PDMS would graft quickly onto surfaces, such as glass or porcelain, forming a durable, oily layer. The researchers brushed the milled oil onto one side of a sterilized toilet’s bowl interior, leaving the other half untreated. Then they poured sterile human urine combined with E. coli and S. aureus bacteria into the toilet and subsequently swabbed what was left behind on both halves of the bowl. Bacteria culture tests showed that the PDMS-treated area inhibited 99.99% of the bacterial growth as compared to the untreated area. Additional experiments showed that both porcelain and glass surfaces coated with the milled PDMS strongly repelled water, suggesting that, in the first test, urine and bacteria slipped right down the treated toilet bowl’s wall. The researchers say that their transparent and colorless toilet bowl treatment method could be a practical way to self-sanitize shared surfaces for public health applications. Continued on page 15
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From the ACS Press Room
Mixing heat with hair styling products may be bad for your health “Siloxane Emissions and Exposures during the Use of Hair Care Products in Buildings” Environmental Science & Technology Hair products often contain ingredients that easily evaporate, so users may inhale some of these chemicals, potentially posing health repercussions. Now, researchers have studied emissions of these volatile organic compounds (VOCs), including siloxanes, which shine and smooth hair. The scientists report in ACS’ Environmental Science & Technology that using these hair care products can change indoor air composition quickly, and common heat styling techniques — straightening and curling — increase VOC levels even more. Some prior studies have examined the amounts of siloxanes released from personal care products. But most foHair care products emit VOCs, and cused on prodthose emissions can worsen when ucts that are hot styling tools are used. washed off the Pormezz/Shutterstock.com body, such as skin cleansers, which might behave differently from products that are left on the hair, like creams or oils. In addition, most previous studies on siloxane emissions haven't looked at the realtime, rapid changes in indoor air composition that might occur while people are acDecember 2023
tively styling hair. Nusrat Jung and colleagues wanted to fill in the details about VOCs released from hair products, especially in real-world scenarios such as small bathrooms where they’re typically applied. The researchers set up a ventilated tiny house where participants used their usual hair products — including creams, sprays and oils — and heated tools. Before, during and after hair styling, the team measured real-time emissions of VOCs including cyclic volatile methyl siloxanes (cVMS), which are used in many hair care products. The mass spectrometry data showed rapid changes in the chemical composition of air in the house and revealed that cVMS accounted for most of the VOCs that were detected. Emissions were influenced by product type and hair length, as well as the type and temperature of the styling tool. Longer hair and higher temperatures released higher amounts of VOCs. As a result of their findings, the researchers estimated that a person’s potential daily inhalation of one cVMS, known as D5, could reach as much as 20 mg per day. In the experiments, turning on an exhaust fan removed most of the air pollutant from the room within 20 minutes after a hair care routine was completed, but the scientists note that this practice could affect outdoor air quality in densely populated cities. They say studies of the long-term human health impacts of siloxane exposure are urgently needed, because most findings are from animal studies. The authors acknowledge funding from Purdue University, the Alfred P. Sloan Foundation and the National Science Foundation.
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From the ACS Press Room
Recent advances in tree nut research — walnuts, pecans and more As the holiday season approaches, many home kitchens will produce the mouthwatering smells of fresh-baked goods and comfort food. From macadamia nut cookies and pecan pies to turkey stuffing, nuts feature heavily in seasonal pastries and dishes. Below are some recent papers published in ACS journals that report new insights into popular tree nuts. Reporters can request free access to these papers by emailing newsroom@acs.org “Bulk and Compound-Specific Stable Isotope Analysis for the Authentication of Walnuts (Juglans regia) Origins” Journal of Agricultural and Food Chemistry Nov. 2, 2023 Some consumers prefer to purchase produce grown in certain places, but country of origin labels can be accidentally incorrect or falsified. So, a team assessed whether two kinds of stable isotope analysis could differentiate walnuts grown in seven countries. A major result of the study was that the amounts of fatty acids and amino acids were significantly different between walnuts grown in the U.S. and China. The researchers say that one of the techniques, compound-specific stable isotope analysis, could be particularly useful to determine the crop’s geographical origins.
“Texture Properties, Crude Fat, Fatty Acid Profiles, Total Soluble Solids, and Total Polyphenols for 21 Pecan Varieties and the Effects of the Harvest Year” ACS Food Science & Technology Oct. 6, 2023 Texture and nutritional content of pecan nuts can differ depending on variety, growing conditions and the harvest year in a tree’s two-year fruit cycle. To learn more about the impact of these factors, a team analyzed kernel texture, crude fat, fatty acids, total soluble solids and total polyphenols in eight common varieties of the nut from two consecutive harvest years. Texture parameters indicated that pecans of the same variety could have different consistencies year-to-year. However, the team determined that the pecan variety had a larger impact on nutritional composition than harvest year. December 2023
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“Dietary Fibers of Tree Nuts Differ in Composition and Distinctly Impact the Fecal Microbiota and Metabolic Outcomes In Vitro” Journal of Agricultural and Food Chemistry June 19, 2023 Most tree nuts are rich in dietary fibers, substances that don’t get digested in the stomach and are instead fermented by gut microbes. Researchers separately ground up almonds, cashews, hazelnuts, pistachios and walnuts, and they measured the percentage of dietary fibers in the samples. Next, they compared the effects of each nut sample on gut microbes in vitro. Of the nuts tested, pistachios had the highest total dietary fiber content, but cashew fibers produced the largest amount of butyrate, a compound that promotes digestive health. However, the team says their results suggest that all tree nut fibers could boost beneficial microbes in the colon.
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From the ACS Press Room
Blasts to clear World War II munitions could contaminate the ocean “Ecotoxicological Risk of World War Relic Munitions in the Sea after Low- and HighOrder Blast-in-Place Operations” Environmental Science & Technology World War II concluded decades ago, but live mines lurking on the ocean floor still pose threats, potentially spewing unexpected geysers or releasing contaminants into the water. Experts conduct controlled explosions to clear underwater munitions, but concerns have arisen over the environmental impacts from these blasts. Now, results in ACS’ Environmental Science & Technology show that the contamination produced by detonation depends on the blast type, with weaker explosions leaving behind more potentially toxic residues. After World War II, according to research estimates, up to 385,000 metric tons of unexploded munitions — including 40,000 tons of chemical munitions — were dumped into the Baltic Sea. These discarded weapons remain dangerous: They have the potential to jet plumes of water and sediment upward, send shock waves through the ocean, and punch holes in ships’ hulls. In addition, the mines’ metal shells can corrode in seawater, leaking potentially toxic explosive compounds, such as TNT, into the environment over time. Technicians typically clear historic munitions with controlled explosions, but there is debate among scientists about whether weak or strong blasts are better. While smaller blasts minimize shock waves and physical damage, Edmund Maser and coworkers suspected that
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these weaker ones release more toxic residue than strong blasts. To test whether this is true, the team wanted to measure the explosive residues near underwater mines after controlled detonations of the two different intensities.
Explosions, as shown here, that clear abandoned war mines can release high levels of TNT, potentially threatening marine life. Uwe Wichert
The researchers — working in close collaboration with the Royal Danish Navy — first identified World War II mines near a busy shipping route off the coast of Denmark, choosing the sites of two intact and two corroded devices. Divers from the Navy collected ocean water and ocean floor sediment around the mines, and researchers then used mass spectrometry to measure the samples’ levels of TNT. As the researchers expected, chemical contamination was higher near the corroded mines than the intact ones.
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From the ACS Press Room
‘Indoor solar’ to power the Internet of Things “Indoor Photovoltaics for the Internet-ofThings − A Comparison of State-of-the-Art Devices from Different Photovoltaic Technologies”
light, whereas indoor lights typically shine light from a narrower region of the spectrum. Scientists have found ways to harness power from sunlight, using PV solar panels, but those panels are not optimized for converting ACS Applied Energy Materials indoor light into electrical energy. Some next -generation PV materials, including perovFrom Wi-Fi-connected home security sys- skite minerals and organic films, have been tems to smart toilets, the so-called Internet of tested with indoor light, but it’s not clear Things brings personalization and conven- which are the most efficient at converting ience to devices that help run homes. But non-natural light into electricity; many of the with that comes tangled electrical cords or studies use various types of indoor lights to batteries that need to be replaced. Now, re- test PVs made from different materials. So, searchers reporting in ACS Applied Energy Uli Würfel and coworkers compared a range Materials have brought solar panel technolo- of different PV technologies under the same gy indoors to power smart devices. They type of indoor lighting. show which photovoltaic (PV) systems work The researchers obtained eight types of PV best under cool white LEDs, a common type devices, ranging from traditional amorphous of indoor lighting. silicon to thin-film technologies such as dyesensitized solar cells. They measured each material’s ability to convert light into electricity, first under simulated sunlight and then under a cool white LED light. •
• Indoor light could someday power smart devices, but traditional solar panel materials aren’t necessarily the best options. LALAKA/Shutterstock.com
•
Indoor lighting differs from sunlight. Light bulbs are dimmer than the sun, and sunlight comprises ultraviolet, infrared and visible
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Gallium indium phosphide PV cells showed the greatest efficiency under indoor light, converting nearly 40% of the light energy into electricity. As the researchers had expected, the gallium-containing material’s performance under sunlight was modest relative to the other materials tested due to its large band gap. A material called crystalline silicon demonstrated the best efficiency under sunlight but was average under indoor light.
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From ACS Press Room Continued
Swapping blood for spit Con- Blasts to clear World War II munitions tinued from page 5 remained stable in undiluted saliva for up to three days and retained sensitivity for up to a week, if washed after each use. Additionally, the glucose sensor shows high selectivity towards its target, and both the AMP and glucose sensors are sensitive enough to detect the biomarkers at much lower concentrations than typically found in saliva. The researchers say that this simple technology is the first of its kind to detect glucose in human saliva, and they hope it can make athome health monitoring less invasive and easier to complete, especially for people with chronic diseases such as diabetes. The authors acknowledge funding from Colgate-Palmolive Company and the Alliance Grant program of the Natural Sciences and Engineering Research Council of Canada. Some authors are employees of ColgatePalmolive’s Research and Development Center. The authors have patents pending on this technology.
Continued from page 12
Then, using either a low-powered detonation or a high-powered detonation, the team destroyed the leaking mines and assessed the TNT released from the blasts. Sediment contained up to 100 million times more TNT after the weaker explosion than before, and only 250 times more TNT after the stronger blast. Similarly, the TNT levels in water after the weaker blast far exceeded those around the stronger one. The researchers say that the pollution released by the low-power blast meets or exceeds levels previously reported to be toxic to microalgae, sea urchins and fish. Because of the potential threats to nearby marine life, the researchers encourage less invasive methods to remediate submerged World War II relics — like robotic techniques to open and remove abandoned mines’ explosive contents — to prevent unwanted explosions and contamination. The authors acknowledge funding from the Interreg North Sea Region’s North Sea Wrecks project.
Slippery toilet bowl treatment Continued from page 8
The authors acknowledge funding from the Erciyes University and the Scientific and Technological Research Council of Turkey.
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From ACS Press Room
Around the Area
Continued
Indoor solar’ Continued from page 13
Graduate students Perouza Parsamian (UT Dallas, Pantano Lab) and Arzoo Patel (UT Arlington, Armstrong Lab) were two of thirty -one nationwide to receive invitations from Pfizer to present their work at this year's Pfizer Chemistry Connect Symposium.
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Gallium indium phosphide has not been used in commercially available PV cells yet, but this study points to its potential beyond solar power, the researchers say. However, they add that the gallium-containing materials are expensive and may not serve as a viable mass product to power smart home systems. In contrast, perovskite mineral and organic film PV cells are less expensive and do not have stability issues under indoor lighting conditions. Additionally, in the study, the researchers identified that part of the indoor light energy produced heat instead of electricity — information that will help optimize future PVs to power indoor devices. The authors acknowledge funding from the Engineering and Physical Sciences Research Council (U.K.), the European Regional Development Fund, the Welsh European Funding Office, First Solar Inc., the German Federal Ministry for Economic Affairs and Energy, and the German Research Foundation.
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From the Editor It’s that time...end of the semester, beginning of holidays, things to do, places to go, people to see! But if you are reading this, you have taken time to read the Southwest Retort, and we thank you! We have this month an article by Dr. Denise Merkle on chem demos, that favorite activity of most chemists, wanting to share the excitement and wonder of chemical reactions...or, like the late great George Hague, a boom show that shook the auditorium (I’m not making that up). The demos I did were always at the elementary grade levels, with no boom, no moths, and no rotten eggs...but at that age, they’re not bored! The Retort would welcome any articles or comments on your demo experiences.
Hope you have a nice start to the winter season!
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