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)
Sunday, December 11, 2022
Scientists propose novel open-path multi-pass cell to measure atmospheric H2O and CO2 fluxes on line
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
ARTICLE PUBLICATION DATE
8-Dec-2022
Phantoms return from beyond the Moon with valuable data on cosmic radiation doses
THE HENRYK NIEWODNICZANSKI INSTITUTE OF NUCLEAR PHYSICS POLISH ACADEMY OF SCIENCES
IMAGE: ZOHAR (IN PROTECTIVE VEST) AND HELGA PHANTOMS INSIDE THE ORION SPACECRAFT.view more
CREDIT: SOURCE: NASA / FRANK MICHAUX
Together with the Orion spacecraft of the Artemis I mission, as part of the MARE experiment, two human phantoms equipped with numerous cosmic rays detectors are to land on Earth. The information gathered by the detectors will for the first time verify the knowledge, crucial for the presence of humans in deep space, of the effects of cosmic rays on the health of the astronauts who are to live and work in an environment devoid of the protective effects of our planet's magnetosphere.
Of the numerous dangers lurking for astronauts undertaking long-distance space travel, among the most serious and at the same time the most difficult to eliminate, is exposure to harmful doses of cosmic radiation. Data collected during the MARE experiment (MATROSHKA AstroRad Radiation Experiment) will help ensure the safety of future deep space pioneers. As part of it, two human phantoms equipped with numerous cosmic radiation detectors were placed aboard the Orion spacecraft of the Artemis I mission. At the invitation of the German Space Centre (DLR) in Cologne, the coordinator of the MARE project, the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow is participating in the experiment.
“MARE is a continuation of a series of experiments carried out on the International Space Station between 2004 and 2009 as part of the MATROSHKA project, in which we also participated. Back then, radiation dose data were necessarily collected in low Earth orbit. Now, thanks to the NASA Artemis I mission, human phantoms stuffed full of radiation detectors have for the first time gone beyond the protective range of not only the Earth's atmosphere, but also the magnetosphere,” says Prof. Pawel Bilski (IFJ PAN).
Cosmic radiation, to which astronauts journeying at great distances from Earth are to be exposed, is extremely complex in nature. Its galactic component comes from deep space and contains all sorts of naturally occurring particles and atomic nuclei, with a very wide range of energies, often far beyond the values encountered under Earthly conditions. Another source of high-energy particles, this time within our planetary system, are eruptions on the Sun, infrequent, but involving serious risk to the health and even the lives of astronauts. In addition, solar wind particles are continuously accumulating around the Earth within two doughnut-shaped areas of the magnetosphere called the Van Allen belts. Although these belts are located at altitudes of only a few thousand kilometres, they have to be traversed twice during any long-distance crewed expedition.
NASA's main goal during the Artemis I mission was to test the Orion crewed spacecraft in an uncrewed circumlunar flight. The lack of passengers was decided to be exploited to verify current knowledge about the effects of cosmic radiation on the human body. As a result, two female phantoms named HELGA and ZOHAR, each weighing 39 kg, were placed inside Orion. The ZOHAR phantom was dressed in AstroRad protective vest, manufactured by the Israeli company StemRad.
In order to gain information about the doses of cosmic radiation absorbed by various parts of the human body, sets of small, passive lithium fluoride radiation detectors were placed every three centimetres throughout the phantoms. In addition, active silicon detectors were installed at key organ sites. In total, more than ten thousand passive detectors and 34 active detectors were installed in both phantoms.
Installation of passive thermoluminescent detectors in the phantom.
CREDIT
Source: DLR
“Our Institute's contribution to the MARE experiment is primarily 276 passive thermoluminescent detectors in the ZOHAR phantom and further 288 detectors in 12 measurement packages on the surface of both phantoms. These detectors are in the form of thin white pellets a few millimetres in diameter,” says Prof. Bilski.
The main material used for the production of the detectors from IFJ PAN is lithium fluoride enriched with carefully selected admixtures. These cause additional metastable energy levels to appear in the material. When cosmic ray particles pass through material composed in such a manner, ionization of atoms occurs. Some of the electrons that are knocked out then end up in the metastable levels where they can stay for months, as if in a trap. What is of key significance is that the more cosmic ray particles pass through the detector, the more electrons are trapped.
The radiation dose recorded by the lithium fluoride detector can be read thanks to the phenomenon of thermoluminescence. In the laboratory, individual detectors are gradually heated to temperatures of several hundred degrees Celsius. The energy supplied causes electrons to start jumping out of successive metastable energy traps. Some of them quickly recombine, accompanied by the emission of photons. The result is a glow, known by physicists as thermoluminescence.
“Our lithium fluoride detectors work in such a way that the amount of light emitted when they are heated is proportional to the dose deposited by cosmic ray particles that have interacted with the material. The reading of the data is therefore reliable and relatively simple, albeit non-trivial. This is because different traps in the material have different properties and empty at different temperatures,” explains Prof. Bilski.
Measurements within the MARE experiment are primarily intended to verify existing knowledge about the effects of cosmic radiation on the human body. The priority is to reduce the risk to astronauts to a minimum, but the research also has a purely practical dimension. This is because the point is to ensure that overly restrictive safety standards do not limit human activity in deep space.
If the return of the Orion spacecraft of the Artemis I mission is successful, the detectors from the ZOHAR and HELGA phantoms will soon return to IFJ PAN for data reading. Preliminary results on the cosmic radiation doses they recorded will be presented by the international MARE experiment team in the first months of next year.
The Artemis I mission was used to collect data on the interaction of cosmic rays with the human body outside the protective shield of the Earth's magnetosphere.
CREDIT
Source: NASA
The Henryk Niewodniczański Institute of Nuclear Physics (IFJ PAN) is currently one of the largest research institutes of the Polish Academy of Sciences. A wide range of research carried out at IFJ PAN covers basic and applied studies, from particle physics and astrophysics, through hadron physics, high-, medium-, and low-energy nuclear physics, condensed matter physics (including materials engineering), to various applications of nuclear physics in interdisciplinary research, covering medical physics, dosimetry, radiation and environmental biology, environmental protection, and other related disciplines. The average yearly publication output of IFJ PAN includes over 600 scientific papers in high-impact international journals. Each year the Institute hosts about 20 international and national scientific conferences. One of the most important facilities of the Institute is the Cyclotron Centre Bronowice (CCB), which is an infrastructure unique in Central Europe, serving as a clinical and research centre in the field of medical and nuclear physics. In addition, IFJ PAN runs four accredited research and measurement laboratories. IFJ PAN is a member of the Marian Smoluchowski Kraków Research Consortium: "Matter-Energy-Future", which in the years 2012-2017 enjoyed the status of the Leading National Research Centre (KNOW) in physics. In 2017, the European Commission granted the Institute the HR Excellence in Research award. As a result of the categorization of the Ministry of Education and Science, the Institute has been classified into the A+ category (the highest scientific category in Poland) in the field of physical sciences.
The Artemis I mission was used to collect data on the interaction of cosmic rays with the human body outside the protective shield of the Earth's magnetosphere. (Source: NASA)
Economical eco-friendly fabrication of high efficiency chalcopyrite solar cells
Researchers in Korea achieve high power conversion efficiency using aqueous spray deposition in air environment
IMAGE: INCHEON NATIONAL UNIVERSITY RESEARCHERS REPORT AN ECO-FRIENDLY, COST-EFFECTIVE, SCALABLE FABRICATION TECHNIQUE FOR HIGH-EFFICIENCY COPPER INDIUM GALLIUM SULFUR DISELENIDE SOLAR CELLS, WHICH USES AQUEOUS SPRAY DEPOSITION IN AIR ENVIRONMENT AND AVOIDS EXPENSIVE VACUUM CONDITIONSview more
CREDIT: JUNHO KIM, INCHEON NATIONAL UNIVERSITY
Clean, sustainable energy solutions are essential to meet the ever-increasing energy demands of the human population. High efficiency solar cells are promising candidates to reduce carbon emissions and achieve carbon neutrality. In this regard, solution-processed copper indium gallium sulfur diselenide solar cells (CIGSSe) solar cells have generated significant interest owing to their excellent photovoltaic properties, such as high absorption of visible light, stability, and tunable bandgap. However, large scale, practical applications are limited by a two-fold challenge. Firstly, solution-based CIGSSe fabrication yields very low power conversion efficiency and often uses solvents that are not environment-friendly. Secondly, to achieve higher power conversion efficiency, fabrication methods rely on expensive vacuum environment that leads to substantial material loss. To this end, a team of researchers led by Professor JunHo Kim from Global Energy Research Center for Carbon Neutrality, Incheon National University, Korea have developed a low-cost and eco-friendly fabrication method of high efficiency CIGSSe solar cells.
In a study made available online on 4 September 2022 and subsequently published in volume 32 Issue 46 of Advanced Functional Materials on 10 November 2022, the researchers used aqueous spray deposition in an air environment and developed a CIGSSe solar cell with power conversion efficiency (PCE) larger than 17 %. “For spray solution, we used deionized water, which is eco-friendly and cheapest solvent till date,” explains Prof. Kim. Moreover, conventional solution-based fabrication processes rely on environmentally hazardous, cadmium-based buffers for the optimization of thin-film solar cells. In this novel technique, the researchers used indium sulfide-based buffer that is a cadmium free, eco-friendly alternative.
The researchers further investigated the alloying effects of zirconium on indium sulfide buffers. Remarkably, the team found that zirconium alloying increases the electron concentration in the buffer. Moreover, this method “passivates” or reduces defect states in the CIGSSe absorber, optimizing the charge transfer between various interfaces, leading to enhanced PCE. Further, the researchers achieved even more defect passivation and higher PCE, of more than 17%, by alloying the CIGSSe absorber with potassium. The fabricated cell has an optimum bandgap for high efficiency applications such as a bottom cell or a tandem cell.
This novel technique is cost-effective and easily scalable as it does not require a vacuum environment. As Prof. Kim observes, “We carried out spray deposition in an air environment without using any high vacuum facility, which significantly reduces fabrication cost and thus makes the fabrication technique more practical and competitive in the industry sector.”
This development simultaneously improves the performance and fabrication of CIGSSe solar cells. This will revolutionize the application of these cells in integrated photovoltaic devices and vehicle integrated photovoltaic devices, and as energy sources for internet of things devices.
Authors: Md Salahuddin Mina1, SeongYeon Kim2, Temujin Enkhbat 1, Enkhjargal Enkhbayar 1, and JunHo Kim1,3
Affiliations:
1Nano Photoelectronic Device Lab, Department of Physics, Incheon National University 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
2Research Center for Thin Film Solar Cells, Daegu-Gyeongbuk Institute of Science and Technology (DGIST) Daegu 42988, Republic of Korea
3Global Energy Research Center for Carbon Neutrality, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
About Incheon National University
Incheon National University (INU) is a comprehensive, student-focused university. It was founded in 1979 and given university status in 1988. One of the largest universities in South Korea, it houses nearly 14,000 students and 500 faculty members. In 2010, INU merged with Incheon City College to expand capacity and open more curricula. With its commitment to academic excellence and an unrelenting devotion to innovative research, INU offers its students real-world internship experiences. INU not only focuses on studying and learning but also strives to provide a supportive environment for students to follow their passion, grow, and, as their slogan says, be INspired.
Dr. JunHo Kim, the corresponding author of the study, is a Professor of Physics at Korea’s Incheon National University. His research group is developing high-efficiency thin-film solar cells with eco-friendly materials such as chalcopyrite, kesterite, and perovskite. He completed his PhD in Physics in 1998 at the Korea Advanced Institute of Science and Technology. Before coming to Incheon National University, he worked as a post-doctoral researcher at University of California, San Diego (1998-2000) and a research staff at the Electronics and Telecommunications Research Institute of South Korea (2000-2004).
IMAGE: JAPAN TRENCH FAST DRILLING PROJECT (JFAST) DRILLING THROUGH THE PLATE BOUNDARY FAULT THAT RUPTURED; THE RESEARCH TEAM COLLECTED CORE SAMPLES TO ANALYZE POST-EARTHQUAKE STRESS.view more
CREDIT: KYOTOU GLOBAL COMMS / JAKE G TOBIYAMA
Kyoto, Japan -- The great 2011 earthquake that caused the tsunami in northeastern Japan is still remembered for its destructive power.
Also known as the Mw 9.0 Tohoku earthquake, the seismic nature of this calamity was not initially entirely clear. While earthquakes resulting from built-up tectonic stress in reverse faulting had only been partially released. In previous studies where complete releases have been posited, the hypothesis was based on seismicity observation and simulation, or on direct stress measurement data above the fault only by using log data.
Now, a team of researchers at Kyoto University has found evidence that a complete stress release may have contributed to the record-breaking event.
"The minor differences between maximum and minimum post-earthquake horizontal stresses near the fault suggest that the Tohoku earthquake occurred upon a complete stress release," explains lead author Weiren Lin.
The team found that both sedimentary formations above and below the plate boundary fault lie in the stress state of normal faults in which vertical stress is greater than maximum horizontal stress.
"Knowledge about stress changes before and after this earthquake, both above and below a gently dipping fault, can provide us insights into how fault slipping caused the ensuing tsunami," the author reflects.
Lin's team was able to collect data for the stress state above the source fault of the Tohoku earthquake, at the boundary between the North American plate and the subducting Pacific plate. However, geophysical data for the stress state below this zone was unreliable.
To address this problem, the team studied one of four drill core samples collected by the Japan Trench Fast -- or JFAST -- Drilling Project from below the source fault and was the first to successfully reveal the stress state at that depth.
"Our new data show good consistency with previous results above the fault, suggesting that combining geophysical data and core samples to comprehensively investigate stress states is effective."
###
The paper "Three-dimensional stress state above and below the plate boundary fault after the 2011 Mw 9.0 Tohoku earthquake" appeared on 9 November 2022 in Earth and Planetary Science Letters, with doi: 10.1016/j.epsl.2022.117888
About Kyoto University
Kyoto University is one of Japan and Asia's premier research institutions, founded in 1897 and responsible for producing numerous Nobel laureates and winners of other prestigious international prizes. A broad curriculum across the arts and sciences at both undergraduate and graduate levels is complemented by numerous research centers, facilities, and offices around Japan and the world. For more information, please see: http://www.kyoto-u.ac.jp/en
