It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
It is hoped that “Water Pollution Sources and Purification: Challenges and Scope“ shall provide guidelines to all interested in research studies of one sort or the other. The book consists of seven chapters, well arranged in a coherent manner.
Chapter one deals with the different water purification techniques used for safe drinking water production, their potential threats, and their challenges. Chapter two focuses exclusively on fluoride removal by adsorption method using activated alumina modified with different materials and isothermal studies. Chapter three is the result-oriented chapter that discusses different parameters affecting photocatalytic degradation of substituted benzoic acids. Chapter four covers the analysis of seasonal and spatial variations of water quality of Dulhara and Ved ponds in Ratnapura, Chhattisgarh, India. Chapter five examines the degradation of benzoic acid by iron nanoparticles as a photo-catalyst using an advanced oxidation process (AOP). This chapter also discusses the synthesis of Fe nanoparticles via hydrothermal process at ordinary temperature and elevated temperature.
Chapter six deals with wastewater treatment using modern methods supported by nanoscale materials. Chapter seven discusses the impact of water mismanagement on the environment and suggests preventive measures for proper water utilization.
The book “Water Pollution Sources and Purification: Challenges and Scope“ targets post-graduate and research scholars in the field of physical sciences, chemistry, and material science who is interested in water treatment, photocatalytic degradation, advanced oxidation process, and solar cell.
About the editors:
Water treatment, Adsorption kinematics, Water purification methods, Properties of nanoparticles in water bodies, Advanced oxidation process, Utilization of water, Photochemical degradation, Environmental impact and health issues, Water quality parameters, Integrated water conservation techniques, Seasonal variation in pond water, Activated alumina and challenges in fluoride removal, Nano-particle aided AOP, Degradation of Benzoic acid, Wastewater purification using nano-scale techniques, Defluoridation , techniques,
Scientists remove yeast cell's sex drive and turn it into a cannabis tracker
Researchers at the University of Copenhagen's Faculty of Science have modified a yeast cell to sense the active substances in cannabis and get it to turn red when it does. The result paves the way for more actors to discover new medicinal substances
Researchers at the University of Copenhagen's Faculty of Science have modified a yeast cell to sense the active substances in cannabis and get it to turn red when it does. The result paves the way for more actors to discover new medicinal substances and for a new type of drug test that can be done with a smartphone.
The researchers also developed a portable plastic device with a yeast cell biosensor in it. Plant material, saliva, urine, blood and other material is placed into the gizmo. The device then uses the smartphone’s camera to see if the yeast cells light up, delivering its result in just 15 minutes. Photo: Getty
Yeast cells are simple organisms. They do two things in life: eat and propagate. Now, researchers at the University of Copenhagen’s Department of Plant and Environmental Sciences have equipped common baker’s yeast cells with a new function.
The researchers substituted the yeast cell’s sex drive with a sense of taste and smell that allows it to detect cannabinoids, the active substances in cannabis. Going one step further, the researchers made the yeast turn red or glow when it successfully detects cannabinoids. The study has been published in Nature Communications.
"We have made a living sensor out of the yeast cell, which can now sense cannabinoids or molecules that have the same function as cannabinoids even if they look very different than cannabinoids. Among other things, the biosensor can be used to look for new substances with the same properties as cannabinoids. This could democratize medicinal development so that pharmaceutical companies aren’t the only ones equipped to discover new substances," says Professor Sotirios Kampranis of the Department of Plant and Environmental Sciences, who headed the research.
CAPTION
Professor Sotirios Kampranis in the lab.
Photo: Emil Blangstrup Toft
Turns red when sensing cannabinoids
Humans use hundreds of different GPCRs (G-protein-coupled receptors) to taste and smell. In our noses alone, 400 different GPCRs make it possible for us to detect and distinguish between the smell of roses and freshly baked bread, each of which activates different GPCRs that then signal the brain.
Along with his research colleagues, Professor Kampranis swapped the GPCR that yeast cells use to sense the opposite sex in an environment, with the GPCR we humans use to recognize cannabinoids. At the same time, the researchers complemented the yeast cell's genetic material with a set of new genes that make it turn red or even glow when it senses cannabinoids nearby.
"The yeast cell now emits a signal when there are cannabinoids in the yeast cell's environment. This allows us to screen thousands of plants for substances with therapeutic potential. And we can also investigate whether people are on drugs or whether someone is trying to smuggle illegal cannabinoids or “designer drugs” through an airport checkpoint," explains Professor Sotirios Kampranis.
Yeast turns red when sensing cannabinoids. Photo: Sotirios Kampranis.
"The yeast cell now emits a signal when there are cannabinoids in the yeast cell's environment. This allows us to screen thousands of plants for substances with therapeutic potential. And we can also investigate whether people are on drugs or whether someone is trying to smuggle illegal cannabinoids or “designer drugs” through an airport checkpoint," explains Professor Sotirios Kampranis.
CREDIT
Sotirios Kampranis
Discovered four new substances in one day
Cannabinoids are known to be connected with sleep, appetite and pain relief. In fact we have them naturally in our bodies where they are calle endocannabinoids. This is precisely why the researchers chose to encode the ability to find cannabinoids in the yeast cells. But in principle, they could have done so for opioids or any other group of medicinal substances.This is precisely why the researchers chose to encode the ability to find cannabinoids in the yeast cells. But in principle, they could have done so for opioids or any other group of medicinal substances.
There is no doubt that the yeast cell can find new substances. In initial tests, the researchers used the yeast cell to study 1600 random substances from a vast chemical compound library available at the University of Copenhagen. It didn’t take long to get a bite.
"In a single day, the yeast cell found four undiscovered substances that had never been associated with anti-inflammatory properties or pain relief, but could potentially be used for these purposes," says Sotirios Kampranis.
When drug companies look for new drugs today, it is with the help of state-of-the-art robotics and laboratory equipment that universities and other non-commercial entities will never be able to afford. That the researchers have developed an alternative, may allow for more people to hunt for helpful substances in nature.
"It's a crowdsourcing approach whereby smaller laboratories can find more new potential substances for pharmaceutical use. I don't see it as competition with pharmaceutical companies – but as something that can create a synergy between independent players in the scientific world and the pharmaceutical industry," says Professor Kampranis.
The Portable biosensor used for smart phones. Photo: Sotirios Kampranis.
The researchers also developed a portable plastic device with a yeast cell biosensor in it. Plant material, saliva, urine, blood and other material is placed into the gizmo. The device then uses the smartphone’s camera to see if the yeast cells light up, delivering its result in just 15 minutes.
CREDIT
Sotirios Kampranis
Smartphone accessory can find drugs
The researchers also developed a portable plastic device with a yeast cell biosensor in it. Plant material, saliva, urine, blood, material from a suitcase, or whatever one would like for the yeast cell to test, is placed into the gizmo.
The device then uses the smartphone’s camera to see if the yeast cells light up, delivering its result in just 15 minutes. The application could be able to help police officers and others track down drugs at airports or administer drug tests.
"We can test for both natural cannabinoids and designer drugs – chemical substances that have very different structures – with the same effects as cannabinoids. In principle, we could also adapt the yeast cell to be able to detect opioids like morphine, fentanyl and oxycodone," says Sotirios Kampranis.
The device can be 3D printed or assembled using materials easily obtained online. The researchers are now working to make the test tool available free of charge, for as many people as possible, but at the same time be able to maintain control for maintenance and further development.
Team undertakes study of lithium deposition behavior in hard carbon hosts
Team’s strategy solves problems found in development of lithium metal anodes
IMAGE: THIS IS A SCHEMATIC ILLUSTRATION OF THE SYNERGISTIC IMPROVEMENT OF LITHIUM DEPOSITION BEHAVIOR IN HYDROCARBON HOST STRUCTURES BY LITHIOPHILIC SITES AND LOCALIZED HIGH-CONCENTRATION ELECTROLYTES, WHICH SHOWS THREE SIGNIFICANT REDUCTIONS IN BOTH ELECTRODE THICKNESS AND DENDRITES GROWTH.view more
CREDIT: NANO RESEARCH, TSINGHUA UNIVERSITY PRESS
While lithium metal is an ideal anode for next-generation high-energy-density batteries, there are challenges to be addressed before it can reach its full potential. A research team has conducted a study of lithium deposition behavior and developed a strategy involving hard carbon hosts that successfully addresses some of the problems currently facing the development of the lithium metal anode. “This strategy addresses the volume change and dendrite problems by rationally designed host and electrolyte, providing a broad perspective for realizing lithium-metal anode,” said Liping Wang, a professor at the University of Electronic Science and Technology of China.
The team published their research in the journal Nano Research on December 07, 2022.
Lithium metal is recognized as a promising anode for next-generation batteries because of its ultra-high theoretical capacity and extremely low electrode potential, and low density. However, lithium metal suffers from uncontrollable lithium dendrite growth, side reactions, and infinite relative volume change. These issues can lower the batteries’ efficiency and shorten the battery cycle life, even possibly leading to short circuit or security risks.
Over time, researchers have suggested various strategies to alleviate dendrite growth and volume expansion. These strategies include constructing three-dimensional composite lithium anodes, optimizing the composition of electrolytes, applying artificial interphases, and using solid-state electrolytes.
The three-dimensional host is the most promising strategy to address the volume expansion and dendrite growth issues. Carbon-based materials are ideal host candidates for lithium-metal anodes because they are lightweight, have high conductivity and many pore structures, along with stable electrochemical/chemical properties. “Yet even with these advantages, the challenges of volume expansion and dendrite growth have not been completely solved by the carbon-based host,” said Wang.
More recently, researchers have explored modifying carbon materials with lithiophilic species (such as zinc, zinc oxide, aluminum, tin, silicon, silver, and magnesium) and developing suitable electrolytes as effective methods to improve the performance of these three-dimensional host materials. “Yet the lithium deposition behavior and its intrinsic mechanism in these processes has not been systematically analyzed,” said Wang.
To better understand the structure-activity relationship and guide the development of high-performance carbon-based host electrodes, the lithium deposition behavior and its intrinsic mechanism, the research team undertook their in-depth study. They used an optical microscope and a scanning electron microscope to systematically study the lithium deposition behavior of the hydrocarbon electrode under different surface modifications and electrolytes. They found that lithium will not spontaneously deposit into the carbon pores, which is significantly dependent on the carbon surface, current density, areal capacity, and electrolyte.
So the team developed a lithiophilic modified commercial hard carbon with silver as a stable host. They discovered that the introduction of lithiophilic sites induced moderate dendrite growth and inhibited volume expansion. They also discovered that localized high-concentration electrolytes proved to be more compatible with lithium and could optimize the lithium deposition morphology instead of the dendrite. Therefore, the silver/hydrocarbon electrode in the localized high-concentration electrolyte exhibited low volume change during cycling, achieved uniform and dendrite-free morphology of lithium deposition, and showed good long-term cycling with high efficiency over 316 cycles.
The team summarized their findings, explaining that although porous carbon has space to theoretically hold lithium, the lithium ions will not deposit into the expected pores because lithium atoms prefer to accumulate in explosive growth mode and are strong enough to prop up the carbon particles. They also discovered that surface modification on carbon can partially moderate lithium deposition with a decreasing nucleation barrier. However, it is not significantly efficient as it is lithium-lithium deposition behavior after lithium is deposited on lithiophilic carbon. The team learned that using localized high-concentration electrolytes is more efficient in achieving a dendrite-free lithium deposition.
The research team includes Ge Zhou, Yulin Zhao, Chuan Hu, Zhenzhen Ren, Hong Li, and Liping Wang from the University of Electronic Science and Technology of China.
This work is funded by National Natural Science Foundation of China, Fundamental Research Funds for the Central Universities, and China Postdoctoral Science Foundation Funded Project.
Nano Research is a peer-reviewed, international and interdisciplinary research journal, publishes all aspects of nano science and technology, featured in rapid review and fast publishing, sponsored by Tsinghua University and the Chinese Chemical Society. It offers readers an attractive mix of authoritative and comprehensive reviews and original cutting-edge research papers. After 15 years of development, it has become one of the most influential academic journals in the nano field. In 2022 InCites Journal Citation Reports, Nano Research has an Impact Factor of 10.269 (9.136, 5 years), the total cites reached 29620, ranking first in China's international academic journals, and the number of highly cited papers reached 120, ranked among the top 2.8% of over 9000 academic journals.
Established in 1980, belonging to Tsinghua University, Tsinghua University Press (TUP) is a leading comprehensive higher education and professional publisher in China. Committed to building a top-level global cultural brand, after 41 years of development, TUP has established an outstanding managerial system and enterprise structure, and delivered multimedia and multi-dimensional publications covering books, audio, video, electronic products, journals and digital publications. In addition, TUP actively carries out its strategic transformation from educational publishing to content development and service for teaching & learning and was named First-class National Publisher for achieving remarkable results.
HEFEI INSTITUTES OF PHYSICAL SCIENCE, CHINESE ACADEMY OF SCIENCES
IMAGE: RESEACHERS WERE SETTING UP SELF-MADE INSTRUMENT FOR COMPARATIVE OBSERVATION EXPERIMENT.view more
CREDIT: GU MINGSI
According to a research recently published in Optics Express, a research team from Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science of Chinese Academy of Sciences proposed a new design for online measurement of atmospheric H2O and CO2 fluxes.
"We designed an open-path and anti-pollution multi-pass cell," said Professor GAO Xiaoming, who led the team, "and applied it on tunable diode laser absorption spectroscopy (TDLAS) sensor."
The new gas analysis instrument exhibited good consistency with commercial instruments, and its accuracy was comparable.
One of the most important ways to reduce greenhouse gas concentrations is by storing carbon in soil and vegetation. Scientists proposes to use the turbulent eddies generated by air flow to measure the emission of greenhouse gases. Equipment based on tunable laser absorption spectroscopy combined with eddy covariance technology has many advantages including high sensitivity, high precision, and fast response. There are two gas path methods for measuring gas fluxes: open-path and closed path. However, the traditional open-path multi-pass cell is unsuitable because its optical path is exposed to air, which causes the coating layer of the lens to be corroded in the atmosphere.
Different from traditional multi-pass cells, this novel anti-pollution open-path multi-pass cell was mainly composed of two plano-convex mirrors coated on a convex surface.
"It's coated on the reverse side," explained GAO. "The design does not allow a direct contact between the coating layer of the lens and air, and that's why it has the anti-pollution effect."
This design effectively avoided the pollution and corrosion of the lens film layer by the external environment. When it was applied to the flux monitoring equipment of atmospheric greenhouse gases CO2 and H2O, the long-term stability and durability of the open-path system was improved.
The design was further proved in a field comparative observation experiment on the CO2 and H2O fluxes of the wheat seasonal farmland ecosystem. The results were in good agreement with those achieved using the Non-dispersive infrared (NDIR)-based commercial instrument.
"We see strong application prospects for flux measurements in any ecosystem," said GAO.
Photograph of the TDLAS sensor and schematic of the open-path TDLAS system used for measuring atmospheric H2O and CO2 concentrations.
Photograph of the installation and comparison of the field measurements obtained using TDLAS and LI-7500 for 24 h.
CREDIT
GU Mingsi
JOURNAL
Optics Express
ARTICLE TITLE
Open-path anti-pollution multi-pass cell-based TDLAS sensor for the online measurement of atmospheric H2O and CO2 fluxes
Some benefits, potential risks with alternative medicines for heart failure
New American Heart Association scientific statement outlines research on complementary and alternative therapies for heart failure
There are some benefits and potentially serious risks when people with heart failure use complementary and alternative treatments to manage symptoms.
People with heart failure should tell their health care team including pharmacists if they are using any over-the-counter or other treatments, such as herbal supplements or exercise programs, other than those prescribed by a health care professional.
Health care professionals should ask patients about alternative therapies during clinic visits, provide guidance on their risks and benefits, and identify if it’s possible to safely integrate them into the care plan.
Practices such as yoga and tai-chi are helpful for people with heart failure, and omega-3 polyunsaturated fatty acids may have benefits for some. However, there are safety concerns with other commonly used over-the-counter remedies or supplements, like vitamin D, blue cohosh and lily of the valley.
DALLAS, Dec. 8, 2022 — There are some benefits and potentially serious risks when people with heart failure use complementary and alternative medicines (CAM), to manage symptoms, so involving the health care team is important for safety, according to a new American Heart Association scientific statement published today in the Association’s flagship, peer-reviewed journal Circulation.
An estimated 6 million people ages 20 and older in the U.S. have heart failure, a condition that occurs when the heart isn’t functioning normally. The statement, “Complementary and Alternative Medicines in the Management of Heart Failure,” assesses the effectiveness and safety of CAM therapies used for heart failure treatment. According to the statement, it’s estimated that more than 30% of people with heart failure in the U.S. use complementary and alternative medicines.
The statement defines complementary and alternative medicine therapy as medical practices, supplements and approaches that do not conform to the standards of conventional, evidence-based practice guidelines. Complementary and alternative products are available without prescriptions or medical guidance at pharmacies, health food stores and online retailers.
“These products are not federally regulated, and they are available to consumers without having to demonstrate efficacy or safety to meet the same standards as prescription medications,” said Chair of the scientific statement writing committee Sheryl L. Chow, Pharm.D., FAHA, an associate professor of pharmacy practice and administration at Western University of Health Sciences in Pomona, Calif., and associate clinical professor of medicine at the University of California in Irvine. “People rarely tell their health care team about their use of supplements or other alternative therapies unless specifically asked, and they may not be aware of the possibility of interactions with prescription medicines or other effects on their health. The combination of unregulated, readily accessible therapies and the lack of patient disclosure creates significant potential for harm.“
Examples of complementary and alternative therapies that heart failure patients might use include supplements such as Co-Q10, vitamin D, Ginkgo, grapefruit juice, devil’s claw, alcohol, aloe vera and caffeine, or practices such as yoga and tai-chi. The statement writing group reviewed research published before Nov. 2021 on CAM among people with heart failure.
The statement writing group advises health care professionals to ask their patients with heart failure at every health care visit about their use of complementary and alternative therapies and talk about potential medication interactions, benefits and potential side effects of CAM. In addition, they suggest that pharmacists are included in the multidisciplinary health care team to provide consultations about the use of complementary and alternative therapies for people with heart failure.
Alternative therapies that may benefit people with heart failure include:
Omega-3 polyunsaturated fatty acids (PUFA, fish oil) have the strongest evidence among complementary and alternative agents for clinical benefit in people with heart failure and may be used safely, in moderation, in consultation with their health care team. Omega-3 PUFA is associated with a lower risk of developing heart failure and, for those who already have heart failure, improvements in the heart’s pumping ability. There appears to be a dose-related increase in atrial fibrillation (an irregular heart rhythm), so doses of 4 grams or more should be avoided.
Yoga and Tai Chi, in addition to standard treatment, may help improve exercise tolerance and quality of life and decrease blood pressure.
Meanwhile, some therapies were found to have harmful effects, such as interactions with common heart failure medications and changes in heart contraction, blood pressure, electrolytes and fluid levels:
While low blood levels of vitamin D are associated with worse heart failure outcomes, supplementation hasn’t shown benefit and may be harmful when taken with heart failure medications such as digoxin, calcium channel blockers and diuretics.
The herbal supplement blue cohosh, from the root of a flowering plant found in hardwood forests, might cause a fast heart rate called tachycardia, high blood pressure, chest pain and may increase blood glucose. It may also decrease the effect of medications taken to treat high blood pressure and Type 2 diabetes.
Lily of the valley, the root, stems and flower of which are used in supplements, has long been used in mild heart failure because it contains active chemicals similar to, but less potent than, the heart failure medicine digoxin. It may be harmful when taken with digoxin by causing very low potassium levels, a condition known as hypokalemia. Lily of the valley also may cause irregular heartbeat, confusion and tiredness.
Other therapies have been shown as ineffective based on current data, or have mixed findings, highlighting the importance of patients having a discussion with a health care professional about any non-prescribed treatments:
Routine thiamine supplementation isn’t shown to be effective for heart failure treatment unless someone has this specific nutrient deficiency.
Research on alcohol varies, with some data showing that drinking low-to-moderate amounts (1 to 2 drinks per day) is associated with preventing heart failure, while habitual drinking or intake of higher amounts is toxic to the heart muscle and known to contribute to heart failure.
There are mixed findings about vitamin E. It may have some benefit in reducing the risk of heart failure with preserved ejection fraction, a type of heart failure in which the left ventricle is unable to properly fill with blood between heartbeats. However, it has also been associated with an increased risk of hospitalization in people with heart failure.
Co-Q10, or coenzyme Q10, is an antioxidant found in small amounts in organ meats, oily fish and soybean oil, and commonly taken as a dietary supplement. Small studies show it may help improve heart failure class, symptoms and quality of life, however, it may interact with blood pressure lowering and anti-clotting medicines. Larger trials are needed to better understand its effects.
Hawthorn, a flowering shrub, has been shown in some studies to increase exercise tolerance and improve heart failure symptoms such as fatigue. Yet it also has the potential to worsen heart failure, and there is conflicting research about whether it interacts with digoxin.
“Overall, more quality research and well-powered randomized controlled trials are needed to better understand the risks and benefits of complementary and alternative medicine therapies for people with heart failure,” said Chow. “This scientific statement provides critical information to health care professionals who treat people with heart failure and may be used as a resource for consumers about the potential benefit and harm associated with complementary and alternative medicine products.”
This scientific statement was prepared by the volunteer writing group on behalf of the American Heart Association’s Clinical Pharmacology Committee and Heart Failure and Transplantation Committee of the Council on Clinical Cardiology; the Council on Epidemiology and Prevention; and the Council on Cardiovascular and Stroke Nursing. American Heart Association scientific statements promote greater awareness about cardiovascular diseases and stroke issues and help facilitate informed health care decisions. Scientific statements outline what is currently known about a topic and what areas need additional research. While scientific statements inform the development of guidelines, they do not make treatment recommendations. American Heart Association guidelines provide the Association’s official clinical practice recommendations.
Co-authors are Vice Chair Biykem Bozkurt, M.D., Ph.D., FAHA; William L. Baker, Pharm.D., FAHA; Barry E. Bleske, Pharm.D.; Khadijah Breathett, M.D., M.S., FAHA; Gregg C. Fonarow, M.D., FAHA; Barry Greenberg, M.D., FAHA; Prateeti Khazanie, M.D., M.P.H.; Jacinthe Leclerc, R.N., Ph.D., FAHA; Alanna A. Morris, M.D., M.Sc.; Nosheen Reza, M.D.; and Clyde W. Yancy, M.D., FAHA. Authors’ disclosures are listed in the manuscript.
The Association receives funding primarily from individuals. Foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific Association programs and events. The Association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and biotech companies, device manufacturers and health insurance providers, and the Association’s overall financial information are available here.
The American Heart Association is a relentless force for a world of longer, healthier lives. We are dedicated to ensuring equitable health in all communities. Through collaboration with numerous organizations, and powered by millions of volunteers, we fund innovative research, advocate for the public’s health and share lifesaving resources. The Dallas-based organization has been a leading source of health information for nearly a century. Connect with us on heart.org, Facebook, Twitter or by calling 1-800-AHA-USA1.
VIDEO: A POWERFUL GREEN LASER HELPS VISUALIZE THE AEROSOL PLUMES FROM A TOILET WHILE IT’S BEING FLUSHED.view more
CREDIT: JOHN CRIMALDI
Thanks to new University of Colorado Boulder research, scientists see the impact of flushing the toilet in a whole new light—and now, the world can as well.
Using bright green lasers and camera equipment, a team of CU Boulder engineers ran an experiment to reveal how tiny water droplets, invisible to the naked eye, are rapidly ejected into the air when a lid-less, public restroom toilet is flushed. Published in Scientific Reports, it is the first study to directly visualize the resulting aerosol plume and measure the speed and spread of particles within it.
These aerosolized particles are known to transport pathogens and could pose an exposure risk to public bathroom patrons. However, this vivid visualization of potential exposure to disease also provides a methodology to help reduce it.
“If it's something you can't see, it's easy to pretend it doesn't exist. But once you see these videos, you're never going to think about a toilet flush the same way again,” said John Crimaldi, lead author on the study and professor of civil, environmental, and architectural engineering. “By making dramatic visual images of this process, our study can play an important role in public health messaging.”
Researchers have known for over 60 years that when a toilet is flushed, solids and liquids go down as designed, but tiny, invisible particles are also released into the air. Previous studies have used scientific instruments to detect the presence of these airborne particles above flushed toilets and shown that larger ones can land on surrounding surfaces, but until now, no one understood what these plumes looked like or how the particles got there.
Understanding the trajectories and velocities of these particles—which can transport pathogens such as E. coli, C. difficile, noroviruses and adenoviruses—is important for mitigating exposure risk through disinfection and ventilation strategies, or improved toilet and flush design. While the virus that causes COVID-19 (SARS-CoV-2) is present in human waste, there is not currently conclusive evidence that it spreads efficiently through toilet aerosols.
“People have known that toilets emit aerosols, but they haven't been able to see them,” said Crimaldi. “We show that this thing is a much more energetic and rapidly spreading plume than even the people who knew about this understood.”
The study found that these airborne particles shoot out quickly, at speeds of 6.6 feet (2 meters) per second, reaching 4.9 feet (1.5 meters) above the toilet within 8 seconds. While the largest droplets tend to settle onto surfaces within seconds, the smaller particles (aerosols less than 5 microns, or one-millionth of a meter) can remain suspended in the air for minutes or longer.
It’s not only their own waste that bathroom patrons have to worry about. Many other studies have shown that pathogens can persist in the bowl for dozens of flushes, increasing potential exposure risk.
“The goal of the toilet is to effectively remove waste from the bowl, but it's also doing the opposite, which is spraying a lot of contents upwards,” said Crimaldi. “Our lab has created a methodology that provides a foundation for improving and mitigating this problem.”
A powerful green laser helps visualize the aerosol plumes from a toilet while it’s being flushed.
On the left, nothing is visible to the naked eye. On the right, a powerful green laser helps visualize the aerosol plumes from a toilet while it’s being flushed.
Aaron True, Postdoctoral Researcher (left) and John Crimaldi pose for a photo with the equipment.
CREDIT
Patrick Campbell / University of Colorado Boulder
Not a waste of time
Crimaldi runs the Ecological Fluid Dynamics Lab at CU Boulder, which specializes in using laser-based instrumentation, dyes and giant fluid tanks to study everything from how odors reach our nostrils to how chemicals move in turbulent bodies of water. The idea to use the lab’s technology to track what happens in the air after a toilet is flushed was one of convenience, curiosity and circumstance.
During a free week last June, fellow professors Karl Linden and Mark Hernandez of the Environmental Engineering Program, and several graduate students from Crimaldi’s lab joined him to set up and run the experiment.
They used two lasers: One shone continuously on and above the toilet, while the other sent out fast pulses of light over the same area. The constant laser revealed where in space the airborne particles were, while the pulsing laser could measure their speed and direction. Meanwhile, two cameras took high resolution images.
The toilet itself was the same kind commonly seen in North American public restrooms: a lid-less unit accompanied by a cylindrical flushing mechanism—whether manual or automatic—that sticks up from the back near the wall, known as a flushometer style valve. The brand-new, clean toilet was filled only with tap water.
They knew that this spur-of-the-moment experiment might be a waste of time, but instead, the research made a big splash.
“We had expected these aerosol particles would just sort of float up, but they came out like a rocket,” said Crimaldi.
The energetic, airborne water particles headed mostly upwards and backwards towards the rear wall, but their movement was unpredictable. The plume also rose to the lab’s ceiling, and with nowhere else to go, moved outward from the wall and spread forward, into the room.
The experimental setup did not include any solid waste or toilet paper in the bowl, and there were no stalls or people moving around. These real-life variables could all exacerbate the problem, said Crimaldi.
They also measured the airborne particles with an optical particle counter, a device that sucks a sample of air in through a small tube and shines a light on it, allowing it to count and measure the particles. Smaller particles not only float in the air for longer, but can escape nose hairs and reach deeper into one’s lungs—making them more hazardous to human health—so knowing how many particles and what size they are was also important.
While these results may be disconcerting, the study provides experts in plumbing and public health with a consistent way to test improved plumbing design and disinfection and ventilation strategies, in order to reduce exposure risk to pathogens in public restrooms.
“None of those improvements can be done effectively without knowing how the aerosol plume develops and how it's moving,” said Crimaldi. “Being able to see this invisible plume is a game-changer.”
Additional authors on this publication include: Aaron True, Karl Linden, Mark Hernandez, Lars Larson and Anna Pauls of the Department of Civil, Environmental, and Architectural Engineering.
JOURNAL
Scientific Reports
ARTICLE TITLE
Commercial toilets emit energetic and rapidly spreading aerosol plumes
