OCTOBER 2022 Southwest Retort

SOUTHWESTRETORT

SEVENTY-FIFTH YEAR October 2022

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 theAmerican Chemical Society in the Southwest Region.

Vol. 75(2) October 2022

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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.

From the ACS Press Room

How Old is that Fingerprint?

“Novel Ambient Oxidation Trends in Fingerprint Aging Discovered by Kendrick Mass Defect Analysis”

ACS Central Science

Forensic dramas on TV make it seem easy to determine when fingerprints were left at the scene of a crime. In reality, the oils in fingerprints degrade over time, and it’s difficult to figure out their age. Now, researchers reporting a small scale study in ACS Central Science have discovered molecular markers for changes to these oils over a seven day time period information that could be used to estimate fingerprints’ages more accurately.

Identifying the age of fingerprints at a crime scene is extremely important evidence when trying to figure out who was really there when the wrongdoing was committed. Previously, Young Jin Lee and colleagues showed that triacylglycerols found in fingerprint oils react with ozone in the air, forming oxidation products, whose presence could be used to estimate when prints were deposited. But ozone reacts with other oils, such as squalene, wax esters, fatty acids and diacylglycerols, generating a complex mixture of oxidation compounds. So, Lee and Andrew Paulson wanted to develop a method to decipher that mixture of compounds and find molecular markers that could more precisely estimate the age of a fingerprint. The researchers had a volunteer place 14 of their thumbprints on glass slides, which were left in the open air at room temperature for up to seven days. Then the team analyzed the fingerprint oils with high resolution mass spectrometry. Using a specialized data visu-

alization tool known as a Kendrick mass defect plot, they identified two new unique molecular trends the presence of epoxides and an increase in medium-length fatty acids. Though their use for estimating fingerprint

age is still to be determined, epoxides were observed in the fingerprints, formed from triacylglycerols, wax esters, fatty acids and diacylglycerols. Interestingly, there was a large increase in the amount of 10 carbon long saturated fatty acids, known as capric acid or decanoic acid, which the researchers suggest comes from ozone reacting with certain carbon carbon double bonds unique to human fingerprints. The researchers say that their next step is to build a model based on the results to determine when fingerprints were deposited.

The authors acknowledge funding from the U.S. National Institute of Justice.

From the ACS Press Room

Nanoplastics can Disrupt Human Liver, Lung Cells’ Processes in Lab Experiments

“Metabolomics Reveal Nanoplastic Induced Mitochondrial Damage in Human Liver and Lung Cells

Environmental Science & Technology

What happens when people unknowingly eat, drink or inhale nearly invisible pieces of plastic? Although it’s unclear what impact this really has on humans, researchers have now taken a step toward answering that question. In ACS’ Environmental Science & Technology, a team reports laboratory results indicating that tiny plastic particles could enter liver and lung cells and disrupt their regular processes, potentially causing adverse health outcomes.

cently have shown that particles less than 100 nm wide can enter animals’ blood and organs, causing inflammation, toxicity and neurological changes. So, Zongwei Cai, Chunmiao Zheng and colleagues wanted to examine the molecular level and metabolic impacts when human lung and liver cells are exposed to similarly sized nanoplastics.

The researchers cultured human liver and lung cells separately in laboratory plates and treated them with different amounts of 80 nm wide plastic particles. After two days, electron microscopy images showed that nanoplastics had entered both types of cells without killing them.

Plastic can’t be avoided in daily life. Many products that we bring into our homes are made of plastic or wrapped in plastic packaging all of which could release microand nanometer sized pieces that could be accidentally consumed or inhaled. Although the health risks to humans from taking in nanoplastics isn’t entirely clear, researchers re-

To learn more about what happened to the cells, the researchers looked at the compounds released by mitochondria crucial energy-producing organelles that are thought to be sensitive to nanoplastics during metabolism. As liver and lung cells were exposed to more nanoplastics, they produced more reactive oxygen species and different amounts of nucleotides, nucleosides, amino acids, peptides and carboxylic acids, indicating that multiple metabolic processes were disturbed. In some cases, mitochondrial pathways appeared to be dysfunctional. These observations demonstrate that while nanoplastics exposure doesn’t kill human lung and liver cells, it could disrupt critical processes, potentially causing negative impacts to organs, the researchers say.

The authors acknowledge funding from the Hong Kong General Research Fund and the National Science Foundation of China.

Celebrating with Green, Eye-catching Sparklers (video) From the ACS Press Room

“Customizing the Appearance of Sparks with Binary Metal Alloys”

ACS Omega

Sparklers can be a lot of fun glimmering, fizzing and spitting out arcs of light from handheld sticks or tubes on the ground. But the metals that they’re usually made with limit what the sparks can look like. Now, researchers in ACS Omega report that rare earth metals in alloy powders can produce flashes that shift from golden to green and continuously branch. Watch a video of the exciting and eye catching sparklers.

Youtube ID: 88fob_WGUbI

Around the world, sparklers are brought out for holidays and special events, providing celebratory pops of light. While their flames can span the colors of rainbow, the flares shooting out have been limited to dark red, gold or bright white light. Recently, Eike Hübner and colleagues found that burning powdered erbium (Er), a rare earth metal, produces a new color changing spark, shifting from golden white to bright green. However, the green phase occurred for just a blip in time and wasn’t really noticeable. Another entertaining aspect of sparkler fountains are their branching sparks that burst apart repeatedly into multiple, smaller particles that flash. Commercial sparklers typically contain iron carbon powders for this effect, but metal -metal alloys can also do this. So, Hübner and the team wanted to test whether rare earth metal metal alloys could be used to create brand new types of color changing or branching sparks.

The researchers pressed single-metal powders and metal metal alloy powders, contain-

ing alkali, transition and rare earth metals, one at a time into a flame. Rare-earth alloys provided more colorful sparks than the single metal powders. For instance, ytterbium produced intense green explosive flashes. But when the ytterbium-copper (Yb-Cu) alloy was burned, it continuously released a shower of long sparks that switched from golden to deep green. Then the researchers combined rare-earth metal alloys with an ammonium perchlorate and nitrocellulose based propellant to create smokeless fountains. A powdered version of neodymium magnets created the most attractive fountain with continuously branching sparks, with each initial “parent spark” shooting off many more sparks in just a fraction of a second. These tests yielded two promising sparkler materials, though the researchers caution that the recipes must undergo further safety testing before they can be used in commercial products.

The authors acknowledge publication funding from the Open Access Publishing Fund of the Clausthal University of Technology.

Report on FallACS Hybrid Council Meeting

The Fall 2022 National ACS Conference was held in Chicago from August 21 25. The meeting was still held in a hybrid fashion, although far more people attended in-person. 11,619 registrations were counted as of August 24, with 9,355 in person and 2,264 virutal.

The ACS Council Meeting was also held in a hybrid format, allowing Council to meet either in-person at the meeting or electronically. Hybrid Council meetings were piloted at the Spring 2022 ACS Conference in San Diego, and things this fall seemed to go smoothly, at least from the remote side of things! Although I was unable to attend the conference in person due to the timing and the beginning of fall classes, I appreciated being able to participate remotely.

In the usual fall business, several elections were held for committees. For the Council Policy Committee (CPC, Raychelle Burks, Anne M. Gaffney, Will E. Lynch, and Frankie K. Wood Black were elected to a three-year term (2023 2025), while Lydia E. M. Hines was elected to serve through the end of 2023. For the Committee on Committees (ConC), William F. Carroll, Jr., Ella L. Davis, Carmen Gauthier, Thomas H. Lane, and Jason E. Ritchie were elected for a threeyear term (2023 2025). For the Committee on Nominations and Elections (N&E), Michelle V. Buchanan, Alan B. Cooper, Kelly M. Elkins, Ellene Tratras Contis, and Kathryn E. Uhrich were elected for a threeyear term (2023 2025).

At least for the calendar year 2023, Council meetings will continue to be held in a hybrid

manner.

As of June 30, 2022, ACS reported $352.5M in total revenue and $308.2M in total expenses. Both of these were higher than the 2021 actual and ahead of the budget. Additionally, the new membership tiers of member, society affiliate, and community associate have shown to be successful, leading to an increase in membership so far in 2022.

A special discussion was led by President Angela Wilson on “ACS for the Future”, posing the following questions:

1. What can be accomplished to enhance theACS experience?

2. Why or how do you think it would make a difference?

3. Who would be tasked with leading this effort (e.g. a section, committee, division, or other)?

The current CEO of ACS, Tom Connelly, plans to retire at the end of this year, and the Board is actively working on finding a successor.

I’ll join in the usual reminders that voting in the national elections is currently active, running from 9/2 10/21/22 at 12:00pm CST. Make sure that you use this opportunity to cast your vote and have your voice heard!

Sincerely,

Rebecca Weber University of North Texas

From the ACS Press Room

How to Tell if that Plastic Bottle or Bag has Recycled Material in it

“Recycled Plastic Content Quantified through Aggregation-Induced Emission”

ACS Sustainable Chemistry & Engineering

To encourage more recycling, the U.K. taxes single-use plastic products containing less than 30% recycled material. But aside from a manufacturer’s word, there isn’t an easy way to verify this composition. Now, researchers reporting in ACS Sustainable Chemistry & Engineering have developed a simple, fraud resistant technique to evaluate the recycled content of new plastic products. They added a fluorescent tag to plastic resins, successfully tracking their amount in products made with various polymers and colors.

After reducing and reusing, recycling is the last line of defense for keeping plastic out of landfills or the environment. And now, some countries are putting financial pressure on manufacturers so they get with the program. Whereas the U.K. is taxing plastic products with little recycled content, other countries, such as Italy and Spain, plan to impose taxes soon on products that contain no recycled content.

Approaches to verify these amounts aren’t always accurate, potentially leading to fraud and public mistrust. One solution could be to tag recycled polymers with the fluorescent molecule 4,4,-bis(2-benzoxazolyl) stilbene (BBS), and then track the tagged plastic feedstocks into resulting products. BBS’s fluores-

cence intensity and color vary when different levels are present. It’s also inexpensive and approved for food contact applications. So, Michael Shaver and colleagues wanted to see how BBS could be used to measure the recycled content of single-use products.

The researchers mixed small amounts of BBS into melted high density polyethylene (HDPE) and then mixed that with virgin HDPE resin, simulating 0 to 100% recycledcontent materials. As the amount of BBS tagged HDPE rose in the samples, the fluorescence intensity shifted toward a greener hue of blue under a fluorescent light. The marked polymer had unique fluorescence properties, which the researchers suggest would be hard for someone with fraudulent intentions to replicate. Next, the team developed a simple digital image analysis technique that converted the material’s fluorescence into the percentage of recycled content. In tests, the method could identify the recycled content in other real world polymers, including recycled milk bottles with additives, colored HDPE, polypropylene and poly (ethylene terephthalate). The BBS strategy could be applied to a variety of single use plastic products without impacting their appearance or quality, the researchers say.

The authors acknowledge funding from the Henry Royce Institute for Advanced Materials, the Sustainable Materials Innovation Hub and the Manchester Institute of Biotechnology.

From the ACS Press Room

SARS-CoV-2 Mimics could accelerate Vaccine Research, make It Safer

“Virus-Like Particles of SARS-CoV‑2 as Virus Surrogates: Morphology, Immunogenicity, and Internalization in Neuronal Cells

ACS Infectious Diseases

Though well known as a respiratory illness, COVID 19 can also affect the nervous system, bringing on headaches and fatigue and wiping out the sense of smell. But it’s unclear whether these symptoms are caused by an immune response or the virus itself invading the central nervous system (CNS). Now, researchers reporting in ACS Infectious Diseases have developed a new tool and possible vaccine candidate that could help scientists understand how SARS CoV 2 could be invading these cells.

Over the past two years, researchers have been trying to get a better understanding of the virus and developing vaccines against it. To date, the U.S. Food and Drug Administration (FDA) has approved four COVID19 vaccines. They offer a great deal of protection against the virus, but some people who have received the shots still catch COVID-19. To develop even better vaccines and treatments, many scientists must conduct experiments with the real virus, which can only be handled in very specialized laboratories. Working with live viruses can put personnel at risk, and the requirement for specially designed settings can limit the scope of research that some teams can perform.

Instead, a safer and easier strategy is to use virus like particles (VLPs), which are molecular mimics that look and act like a cer-

tain virus without being infectious. The particles can even serve as a vaccine themselves, as is the case with two that are currently available against the human papillomavirus. Researchers have developed VLPs of SARSCoV 2 previously but have yet to specifically study how they affect the CNS. So, Manidipa Banerjee and colleagues wanted to create SARS CoV 2 VLPs and run them through tests to see whether they function like the real deal and could be used one day as vaccines.

The researchers made VLPs with the four major structural proteins of SARS-CoV-2 the spike, membrane, envelope and nucleocapsid and allowed them to self assemble into small, spherical particles. The particles looked similar to SARS CoV 2 and could bind ACE2, which the virus latches onto to enter human cells. In other experiments, the team showed that the VLPs could get into brain cells in petri dishes, and the process depended on both cholesterol and an enzyme called dynamin. In addition, the VLPs tricked the immune system into launching a counterattack in mice, just as it does against SARS CoV 2. The researchers say that VLPs could, therefore, be used in future vaccine development research and to get a better handle on what makes this new virus tick.

The authors do not acknowledge a funding source for this study

As the National Chemistry Week Coordinator for the Dallas Fort Worth Region of the American Chemical Society, for the 2022 event on October 22 from 10-2 p.m. at the Fort Worth Museum of Science and History. Volunteers from eleven university and high school groups will be providing demonstrations and other activities to help celebrate chemistry with museum guests.

Best regards, Kayla Green, NCW Coordinator for the DFW Region

From the ACS Press Room

Tiny, Caterpillar-like Soft Robot Folds, Rolls, Grabs and Degrades (video

“Soft Tunable Gelatin Robot with Insectlike Claw for Grasping, Transportation, and Delivery” ACS Applied Polymer Materials

When you hear the term “robot,” you might think of complicated machinery working in factories or roving on other planets. But “millirobots” might change that. They’re robots about as wide as a finger that someday could deliver drugs or perform minimally invasive surgery. Now, researchers reporting in ACS Applied Polymer Materials have developed a soft, biodegradable, magnetic millirobot inspired by the walking and grabbing capabilities of insects. Watch a video of the bioinspired robot.

Youtube ID: 1va-OQvfJDg

Some soft millirobots are already being developed for a variety of biomedical applications, thanks to their small size and ability to be powered externally, often by a magnetic field. Their unique structures allow them to inch or roll themselves through the bumpy tissues of our gastrointestinal tract, for example. They could someday even be coated in a drug solution and deliver the medicine exactly where it’s needed in the body. However, most millirobots are made of non-degradable materials, such as silicone, which means they’d have to be surgically removed if used in clinical applications. In addition, these materials aren’t that flexible and don’t allow for much fine tuning of the robot’s properties, limiting their adaptability. So, Wanfeng Shang, Yajing Shen and colleagues wanted to

create a millirobot out of soft, biodegradable materials that can grab, roll and climb, but then easily dissolve away after its job is done.

As a proof of concept, the researchers created a millirobot using a gelatin solution mixed with iron oxide microparticles. Placing the material above a permanent magnet caused the microparticles in the solution to push the gel outward, forming insect-like “legs” along the lines of the magnetic field. Then, the hydrogel was placed in the cold to make it more solid. The final step was to soak the material in ammonium sulfate to cause cross linking in the hydrogel, making it even stronger. Changing various factors, such as the composition of the ammonium sulfate solution, the thickness of the gel or the strength of the magnetic field allowed the researchers to tune the properties. For example, placing the hydrogel farther away from the magnet resulted in fewer, but longer, legs.

Because the iron oxide microparticles form magnetic chains within the gel, moving a magnet near the hydrogel caused the legs to bend and produce a claw like grasping motion. In experiments, the material gripped a 3D printed cylinder and a rubber band and carried each one to new locations. In addition, the researchers tested the millirobot’s ability to deliver a drug by coating it in a dye solution, then rolling it through a stomach model. Once at its destination, the robot unfurled and released the dye with the strategic use of magnets. Since it’s made using water-

From the ACS Press Room

Colorful Solar Panels could make the Technology More Attractive

“High-Efficiency, Mass-Producible, and Colored Solar Photovoltaics Enabled by Self Assembled Photonic Glass” ACS Nano

Solar panels aren’t just for rooftops anymore some buildings even have these power generating structures all over their facades. But as more buildings and public spaces incorporate photovoltaic technologies, their monotonous black color could leave onlookers underwhelmed. Now, researchers reporting in ACS Nano have created solar panels that take on colorful hues while producing energy nearly as efficiently as traditional ones.

vantage of microscopic shapes to only reflect a very narrow, selective portion of light, like the scales on butterfly wings. However, previous technologies attempting to incorporate structural color gave panels an undesirable iridescence or were expensive to implement at a large scale. So, Tao Ma, Ruzhu Wang, and colleagues wanted to develop a way of giving solar panels color using a structural material that would be easy and inexpensive to apply, and that would maintain their ability to produce energy efficiently.

Solar panels are typically a deep black color because their job is to absorb light, whereas a red car looks red because the finish reflects red light instead of absorbing it. Most attempts to give these devices color, then, will decrease their ability to absorb light and generate power. One alternative is to use structural sources of color that take ad-

The team sprayed a thin layer of a material called a photonic glass onto the surfaces of solar cells. The glass was made of a thin, disorderly layer of dielectric microscopic zinc sulfide spheres. Although most light could pass through the photonic glass, selective colors were reflected back based on the sizes of the spheres. Using this approach, the researchers created solar panels that took on blue, green and purple hues while only dropping the efficiency of power generation from 22.6% to 21.5%. They also found that solar panels manufactured with this photonic glass layer maintained their color and performance during standard durability tests, and that the fabrication could be scaled up. The researchers plan to explore ways to make the colors more saturated, as well as methods to achieve a wider range of colors.

The authors acknowledge funding from the National Natural Science Foundation of China.

From the Editor

It’s National Chemistry Week! Back when it was National Chemistry Day 10/23, of course we started with bang-up shows (literally) with the late great George Hague. The first one we did was catered thanks to my sister in law, who drove a delivery truck and gave us all the out-of-date cookies and other munchies. Well, it has evolved greatly since then, both nationally and in our section. The big event this year will be on October 22 from 10 2 p.m. at the Fort Worth Museum of Science and History...hope you can be there.

For me, most interesting press release this month deals with the age of fingerprints...determining not just who was there but when. Once a standardized method is worked out, that should be a great step forward for forensic groups.