New ammonia production method could open doors for alternative fuel, energy storage

Peer-Reviewed Publication

TSINGHUA UNIVERSITY PRESS

 

IMAGE: THE ASSEMBLED ZN–NO BATTERY SHOWS SUPERIOR PERFORMANCE FOR AMMONIA PRODUCTION. view more 

CREDIT: NANO RESEARCH ENERGY, TSINGHUA UNIVERSITY PRESS

A solution to climate change could be sitting under your bathroom sink. Ammonia, a compound of nitrogen and hydrogen (NH3) that is commonly known for its use as a household cleaner, could be used as an alternative fuel for vehicles or as a potential energy storage medium. However, traditional methods of producing ammonia from nitrogen oxide (NO) on a large scale are not energy efficient, and some of the more recent efforts to produce ammonia from an NO reduction reaction have low ammonia yields. Now, researchers from Tsinghua University Press in China have developed an eco-friendly, energy-efficient method for producing ammonia through an electrocatalytic NO reduction reaction.

The work was published in the journal Nano Research Energy on July 07.

“The industrial-level NH3 production is still heavily relying on the Haber–Bosch process, requiring drastic reaction conditions due to the sluggish kinetics, and the energy input aspect of the process inevitably results in a large amount of greenhouse gas emissions,” said corresponding author Xijun Liu of the School of Resource, Environments and Materials at Guangxi University in Nanning, China. His reference to the Haber-Bosch process alludes to one of the first — and, since its development in the early 1900s, one of the most common — NH3 production processes.

Because of these drawbacks, previous research has explored electrocatalytic — simply, a catalyst in an electromagnetic reaction — ammonia production in water because of its zero-carbon output using noble metal-based materials, carbon-based materials and single-atom catalysts. However, the yield rate was far lower than the U.S. Department of Energy target, according to the researchers.

The researchers explored NO reaction reduction (NORR) to ammonia using the synthesis of nanoporous vanadium nitride (VN) film supported on carbon fiber cloth (written as np-VN/CF). They tested the new method, the novelty of which lies with using existing materials of VN film in a new way and for a new purpose, with a zinc-nitrogen oxide battery.

“This designed catalyst shows a high power density and a high corresponding ammonia yield rate when used as the cathode in a home-assembled Zn–NO battery,” Liu said. “We also found that the faraday efficiency ¾ or how well the electrons, or charge, are transferred in an electrochemical transformation ¾ was improved. The achieved NORR performance metrics are comparable to the recently reported best results.”

The high faraday efficiency can be attributed in part to the fact that part of the nitrogen was “doped” into carbon fiber cloth, making it more likely to be highly conductive and therefore favor the charge transfer.

To test the method with the battery, the researchers bubbled NO feeding gas into the cathode — or negatively charged portion of a battery — chamber of the battery, which was separated from the positive charge by a bipolar membrane. The obtained Zn-NO battery performance outperformed previously reported results, according to the researchers. The measurements attained from the experiments were tested in a three-electrode system and compared with the NORR activity of a commercial VN powder—as opposed to film—cast onto a carbon fiber cloth. The VN film version outperformed the powder version, which had been used in previous research, in all of the measurements taken. The researchers also performed density functional theory computations to offer an in-depth insight into NORR.

“Our work shows the potential application of nanoporous materials for high-performance electrochemical NH3 production,” Liu said.

Next steps for the research would include efforts to scale the proof-of-concept demonstrated in this experiment.

“This work further confirms that the electroreduction of NO is a promising strategy for ambient ammonia synthesis that should be continuously developed,” Liu said.

The Natural Science Foundation of China and the Tianjin Science Fund for Distinguished Young Scholars funded this research.

The other authors of the paper are Defeng Qi of the School of Resource, Environments and Materials at Guangxi University and of the School of Materials Science and Engineering at Tianjin University of Technology, Tianjin China; Fnag Lv, Mengmeng Jin and Jun Luo of the School of Materials Science and Engineering at Tianjin University of Technology; Tianran Wei and Dui Ma of the School of Resource, Environments and Materials at Guangxi University; Ge Meng of the College of Chemistry and Materials Engineering at Wenzhou University in Wenzhou, China; Shusheng Zhang of the College of Chemistry in Zhengzhou University in Zhengzhou, China; Qian Liu of Chengdu University in Chengdu, China; Wenxian Liu of the College of Materials Science and Engineering; and Mohamed S. Hamdy of the Department of Chemistry, College of Science at King Khalid University in Abha, Saudi Arabia.

About Nano Research Energy 

Nano Research Energy is launched by Tsinghua University Press, aiming at being an international, open-access and interdisciplinary journal. We will publish research on cutting-edge advanced nanomaterials and nanotechnology for energy. It is dedicated to exploring various aspects of energy-related research that utilizes nanomaterials and nanotechnology, including but not limited to energy generation, conversion, storage, conservation, clean energy, etc. Nano Research Energy will publish four types of manuscripts, that is, Communications, Research Articles, Reviews, and Perspectives in an open-access form.

About SciOpen 

SciOpen is a professional open access resource for discovery of scientific and technical content published by the Tsinghua University Press and its publishing partners, providing the scholarly publishing community with innovative technology and market-leading capabilities. SciOpen provides end-to-end services across manuscript submission, peer review, content hosting, analytics, and identity management and expert advice to ensure each journal’s development by offering a range of options across all functions as Journal Layout, Production Services, Editorial Services, Marketing and Promotions, Online Functionality, etc. By digitalizing the publishing process, SciOpen widens the reach, deepens the impact, and accelerates the exchange of ideas.

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JOURNAL

Nano Research Energy

DOI

10.26599/NRE.2022.9120022 

ARTICLE TITLE

High-efficiency electrocatalytic NO reduction to NH3 by nanoporous VN

Behind the scenes of the $3.7 million hydrogen energy ‘earthshot’ at UVA

Energy Secretary Jennifer Granholm announced the award during her visit

Grant and Award Announcement

UNIVERSITY OF VIRGINIA

 

IMAGE: CHARLES MACHAN, AN ASSOCIATE PROFESSOR OF CHEMISTRY, TELLS SECRETARY OF ENERGY JENNIFER GRANHOLM AND ASMERET ASEFAW BERHE, THE ENERGY DEPARTMENT’S DIRECTOR OF THE OFFICE OF SCIENCE, ABOUT THE MOLECULAR PORTION OF THE RESEARCH. view more 

CREDIT: PHOTO BY DAN ADDISON, UVA COMMUNICATIONS

The U.S. Department of Energy announced Thursday that the University of Virginia will receive $3.7 million to pioneer clean energy through a more efficient “green” way of producing hydrogen.

Hydrogen?

Yes, the world’s lightest element and the most abundant element in the universe could also be an answer to two of the world’s most vexing problems: high energy demand and climate change.

The three-year grant is part of the current administration’s “Earthshot” challenge to move the nation to net-zero carbon emissions by 2050.

On the heels of Energy Secretary Jennifer Granholm’s visit to the University to make the announcement, here’s what’s you need to know about the work UVA is leading.

The Team Unlocking Hydrogen

Hydrogen, which can be produced by the molecular separation of water in a process known as “water splitting,” has the potential to be a major component of an overarching clean energy plan.

If it can be produced cheaply enough on an industrial scale through a process called electrolysis, using a plentiful renewable energy source such as solar energy to drive the reaction, the positive environmental and economic impacts would be substantial, experts say.

Sen Zhang, a UVA associate professor of chemistry who serves as the project’s principal investigator and team lead, said if the research is successful, it “will potentially transform the U.S. and global energy portfolio.”

Commonwealth Professor of Chemistry T. Brent Gunnoe, a co-investigator on the project, agreed.

“If you can produce inexpensive hydrogen using solar energy, it opens the door to paradigm shift for energy production and use,” Gunnoe said. “It really opens up an enormous range of options, including both energy and large-scale chemical production that is necessary for modern society.”

Zhang and Gunnoe will partner with two other faculty members in the Chemistry Department: Charles Machan, an associate professor of chemistry, and Huiyuan Zhu, a newly hired assistant professor of chemistry.

The professors will be assisted by undergraduate and graduate students on the effort.

The University will also team up with co-investigators from Brookhaven National Laboratory, the California Institute of Technology, Columbia University and the University of Delaware to work on separate but related aspects of the challenge.

The project dovetails with UVA’s Grand Challenge to generate research that promotes environmental resilience and sustainability.

The Opportunities Ahead

Carbon dioxide, emitted from cars and industry, is considered one of the major contributors to climate change.

If hydrogen were cheaper, hydrogen fuel-cell vehicles, which use compressed hydrogen gas and emit only water, would become more viable. However, these vehicles still have some challenges to overcome. Range of travel and the relatively more flammable fuel are concerns.

But for these UVA researchers, the bigger play is liquid engine fuels made with a process that doesn’t require new petroleum extraction.

Scientists know how to combine hydrogen with carbon dioxide to produce liquid fuels that are safe to use, Zhang said. And they know how to capture carbon dioxide from the atmosphere – although this vision requires the development of large-scale technologies for capture.

In theory, scaling up fuel made from cleaned air and clean hydrogen obtained through renewable energy would mean ratcheting down the amount of carbon dioxide being added to the air – creating a clean energy win.

And that’s just vehicles. Clean hydrogen could serve as a source of energy for power hogs such as computer data centers, while revolutionizing the production of fertilizer and other products. Currently, the hydrogen to produce ammonia in fertilizer is accessed using fossil resources, and it’s responsible for the addition of massive amounts of carbon dioxide to the atmosphere, Gunnoe said.

The sticking point to utilize clean hydrogen is cost. Researchers need to find a way to produce the hydrogen at about a fifth of the current expense in order to reach market feasibility, the Department of Energy says.

Zhang confirmed UVA is up for the challenge.

“Our project aligns with the Department of Energy's ‘1-1-1’ mission of reducing the hydrogen production cost using water electrolyzers to $1 per one kilogram in one decade,” he said.

The Tech They’ll Be Working On

So what exactly is an electrolyzer?

It’s the apparatus that will produce the hydrogen. The device relies on a chemical process activated by electricity (such as through solar energy) to split the H2O molecules.  

Specifically, the researchers are investigating the component parts of an emerging type of water electrolyzer that uses hydroxide. The chemical compound is stored in a central solid polymer membrane to help separate out the hydrogen from the oxygen.

The team essentially wants to figure out ways to make the core reaction that takes place faster and the materials used more robust.

“The materials used currently as electrocatalysts in water electrolyzers are too expensive, too slow, and they’re not stable enough,” Gunnoe said.

Gunnoe and Machan will work on developing tailored molecules for the reaction that splits the water.

Zhang and Zhu will use those molecules to create the advanced materials that will function as the catalyst in the electrolyzer.

The affiliated researchers outside of UVA will work on other aspects of the electrolyzer, including durability testing and computational design – on up to eventually building a full protype with the most ideal components, Zhang said.

The Exciting Future

The researchers are going to see how fast they can move the needle forward over the course of the three-year grant.

“It is a very bold and ambitious vision for the future,” Gunnoe said. “I don’t want to paint the picture that we are two or three years from this at the industrial level. There is a tremendous amount of science that needs to evolve. Under Sen’s leadership and with our talented partners, I am confident that we are going to make significant contributions over the next three years.”

Fourth-year chemistry student Shen-Wei Yu said he is passionate about working on the project because it’s green from start to finish.

“I’m excited because we can use renewable energy such as solar to get a very clean hydrogen,” Yu said.

Tangi Akauola, a second-year graduate student, said working on the project appeals to his sense of civic duty.

“What motivated me to join the Zhang lab is that we’re at the heart of creating an infrastructure in this country that can support a clean sustainable energy in the form of hydrogen gas,” Akauola said.

He added that, as a generation, “We care a lot about the future of this country, because it’s the country we’ll inherit.”

The students working on the project, along with chemistry faculty members and UVA administrators, were among those lucky enough to meet with Granholm during last week’s visit, which included a guided lab tour and enthusiastic remarks from UVA President Jim Ryan.

The energy secretary congratulated UVA on landing the project and broadly touted the future of hydrogen, which she said will include not only new technological development, but investment in regional hubs for hydrogen production.

Latest city-level emission accounting in China: cities are on the track toward net-zero emissions and 38 have achieved emission peak

Peer-Reviewed Publication

SCIENCE CHINA PRESS

 

IMAGE: 38 CITIES HAVE PROACTIVELY PEAKED THEIR EMISSIONS FOR AT LEAST FIVE YEARS AND 21 CITIES HAVE REDUCED EMISSIONS PASSIVELY. ANOTHER 20 CITIES ARE AT A PLATEAU PHASE OF EMISSIONS. THE REMAINING 139 CITIES ARE STILL INCREASING THEIR EMISSIONS. view more 

CREDIT: ©SCIENCE CHINA PRESS

This study is led by Assoc. Prof. Yuli Shan (University of Birmingham / University of Groningen), Yuru Guan (PhD researcher, University of Groningen), Prof. Dabo Guan (Tsinghua University), Prof Klaus Hubacek (University of Groningen) and 5 other researchers. The study presents the most comprehensive and long-reaching time series (2001 to 2019) of CO2 emission inventories of 287 Chinese cities, covering 98%+ of China’s population, 99%+ of GDP, and 97%+ of CO2 emissions (compared to the national emissions from EDGAR) in 2014.

The emission inventories were compiled for 47 economic sectors and included energy-related emissions for 17 types of fossil fuels and process-related emissions from cement production. The inventories capture all direct emissions from human economic activities within the city boundary based on the administrative-territorial accounting approach recommended by the Intergovernmental Panel on Climate Change (IPCC). Dr Shan tells us “This accounting approach has been widely used for designing low-carbon policies and allocating responsibility for global climate change targets”. “It's also worth mentioning that the emission factors of fossil fuels we used were collected from our previous studies, which are based on a wide survey of over 4,243 state-owned Chinese coal mines in China”, Dr Shan emphasizes.

Prof. Guan mentions that “this city-level emission estimates are consistent with our CEADs team’s previous accounting of national and provincial emissions in terms of methods, scope, and data sources. So, we are now able to compare emissions across scales”. Prof. Guan and Dr. Shan have established an open-access dataset called CEADs (Carbon Emission Accounts and Datasets for Emerging Economies) since 2016. CEADs team works on the emission accounting methods and applications for China and other emerging economies. Dr Shan is the subject leader in environmental accounting and Prof. Guan is the founder of CEADs.

Based on the long time-series city-level emission data, Dr Shan and his colleagues tested the status of the emissions peak in 287 Chinese cities based on several conditional functions, the Mann-Kendall (MK) trend test, and cities’ decoupling of emissions and social development indexes (e.g., level of economic development and size of the population). The MK trend test is a nonparametric statistical method recommended by the World Meteorological Organization (WMO) and has been widely used to detect time-series trends of climate sequences.

They found that 38 Chinese cities have proactively peaked their emissions (i.e., cities reduced emissions significantly for at least five years while economy and population kept increasing), 21 cities have passively declined their emissions (i.e., cities have achieved emission decline for more than five years but their economy or population also decreased during the same period), 20 cities are at a plateau phase (i.e., emissions declined for more than five years but might rebound to a higher level afterward), and the remaining 139 cities are still increasing their emissions or reduced emissions temporarily for less than five years. Looking into the emission drivers in each city, Dr Shan found that proactively peaked cities have achieved emission decline mainly due to efficiency improvements and structural changes in energy use, while passively emission declined cities have an economic recession or population loss as one possible reason for emission decline.

This study provides policy recommendations for achieving emission peaks and carbon neutrality in different types of cities. “It is not easy to reduce every ton of emissions”, Dr Shan says, “the reduction strategy cannot be designed with one-size-fits-all mitigation policies for all cities, but has to be individualized, considering cities’ resource endowment, industrialization level, socio-economic characteristics, and development goals.” Prof. Hubacek says that “emission peaked cities should provide successful models for other non-peaked cities. Super emitters with laggard technologies and production efficiency should have more stringent policies and targets for emission reduction, while less developed regions could have more emission space for economic development.”

This study also suggests that passively emission declined cities need to face up to the reasons that caused the emission to decline, and fully exploit the opportunities provided by industrial innovation and green investment brought by the low-carbon targets to achieve economic recovery and carbon mitigation goals. The proactively peaked cities need to seek strategies to maintain the downward trend in emissions and avoid an emission rebound.

The latest emission inventories of Chinese cities are now freely available (for non-commercial use only) to the public and the scientific community from CEADs dataset website (https://ceads.net/data/city/). Please cite the following papers when using the data.

1. Shan et al. City-level emission peak and drivers in China (2022) Science Bulletin.
2. Shan et al. City-level climate change mitigation in China (2018) Science Advances’
3. Shan et al. Methodology and applications of city level CO2 emission accounts in China.  (2017) Journal of Cleaner Production
4. Shan et al. An emissions-socioeconomic inventory of Chinese cities (2019) Scientific Data

See the article:

Shan et al. City-level emission peak and drivers in China (2022) Science Bulletin.

https://doi.org/10.1016/j.scib.2022.08.024

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JOURNAL

Science Bulletin

DOI

10.1016/j.scib.2022.08.024 

Researchers of the Human Brain Project identify seven new areas in the insular cortex

Peer-Reviewed Publication

HUMAN BRAIN PROJECT

 

IMAGE: PROBABILITY MAPS OF THE SEVEN NEWLY DISCOVERED AREAS OF THE INSULAR CORTEX view more 

CREDIT: IMAGE FROM QUABS ET AL. 2022 (CC BY 4.0) HTTPS://WWW.SCIENCEDIRECT.COM/SCIENCE/ARTICLE/PII/S1053811922005699?VIA%3DIHUB

All newly detected areas are now available as 3D probability maps in the Julich Brain Atlas, and can be openly accessed via the HBP’s EBRAINS infrastructure. Their findings, published in NeuroImage, provide new insights into the structural organisation of this complex and multifunctional region of the human neocortex.

The human insular cortex, or simply “insula”, has gained the attention from researchers since the early 19th century. But a 3D cytoarchitectonic map of the insula that could be linked to neuroimaging studies addressing different cognitive tasks was thus far not available.
 
The HBP team from the University of Düsseldorf and Forschungszentrum Jülich analysed images of the middle posterior and dorsal anterior insula of ten human brains and used statistical mapping to calculate 3D-probability maps of seven new areas. The probability maps reflect the interindividual variability and localisation of the areas in a three-dimensional space.

Brain areas with differences in their cytoarchitecture - or the organisation of their cellular composition - also likely differ in function. Based on this hypothesis, the researchers aimed to better understand the differences in the microstructure of the insula, and to identify areas that may correlate with its diverse and complex multifunctionality. 

CAPTION

Maximum probability map of seven newly discovered areas of the human insula

CREDIT

Image from Quabs et al. 2022 (CC BY 4.0) https://www.sciencedirect.com/science/article/pii/S1053811922005699?via%3Dihub

The team found that the microstructure of the insula has a remarkable diversity and a broad range of cytoarchitectonic features, which might be the basis for the complex functional organisation in this brain region.

A cluster analysis based on cytoarchitecture resulted in the identification of three superordinate microstructural clusters in the insular cortex. The clusters revealed significant differences in the microstructure of the anterior and posterior insula, reflecting systematic functional differences between both entities. 

The new maps are now openly available in the Human Brain Project’s Multilevel Human Brain Atlas on EBRAINS to support future studies addressing relations between structure and function in the human insula.

Text by Helen Mendes

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JOURNAL

NeuroImage

DOI

10.1016/j.neuroimage.2022.119453 

ARTICLE TITLE

Cytoarchitecture, probability maps and segregation of the human insula

How light and temperature work together to affect plant growth

The findings may help scientists develop more resilient plants to help withstand climate change

Peer-Reviewed Publication

SALK INSTITUTE

 

IMAGE: ARABIDOPSIS THALIANA CELLS (TOP) AND SEEDLINGS (BOTTOM) IN DIFFERENT LIGHT AND TEMPERATURE CONDITIONS. THE SEEDLINGS PICTURED ON THE FAR RIGHT SHOW ACCELERATED GROWTH IN RESPONSE TO SHADE AND WARM TEMPERATURES. view more 

CREDIT: SALK INSTITUTE COURTESY OF NATURE COMMUNICATIONS

LA JOLLA—(August 29, 2022) Plants lengthen and bend to secure access to sunlight. Despite observing this phenomenon for centuries, scientists do not fully understand it. Now, Salk scientists have discovered that two plant factors—the protein PIF7 and the growth hormone auxin—are the triggers that accelerate growth when plants are shaded by canopy and exposed to warm temperatures at the same time.

The findings, published in Nature Communications on August 29, 2022, will help scientists predict how plants will respond to climate change—and increase crop productivity despite the yield-harming global temperature rise.

“Right now, we grow crops in certain densities, but our findings indicate that we will need to lower these densities to optimize growth as our climate changes,” says senior author Professor Joanne Chory, director of Salk’s Plant Molecular and Cellular Biology Laboratory and Howard Hughes Medical Institute investigator. “Understanding the molecular basis of how plants respond to light and temperature will allow us to fine-tune crop density in a specific way that leads to the best yields.”

During sprouting, seedlings rapidly elongate their stems to break through the covering soil to capture sunlight as fast as possible. Normally, the stem slows down its growth after exposure to sunlight. But the stem can lengthen rapidly again if the plant is competing with surrounding plants for sunlight, or in response to warm temperatures to increase distance between the hot ground and the plant’s leaves. While both environmental conditions—canopy shade and warm temperatures—induce stem growth, they also reduce yield.

In this study, the scientists compared plants growing in canopy shade and warm temperatures at the same time—a condition that mimics high crop density and climate change. The scientists used the model plant Arabidopsis thaliana, as well as tomato and a close relative of tobacco, because they were interested to see if all three plant species were affected similarly by this environmental condition.

Across all three species, the team found that the plants grew extremely tall when simultaneously trying to avoid the shade created by neighboring plants and being exposed to warmer temperatures. On a molecular level, the researchers discovered that transcription factor PIF7, a protein that helps turn genes “on” and “off,” was the dominant player driving the increased rapid growth. They also found that the growth hormone auxin increased when the crops detected neighboring plants, which fostered growth in response to simultaneous warmer temperatures. This synergistic PIF7-auxin pathway allowed the plants to respond to their environments and adapt to seek the best growing conditions

A related transcription factor, PIF4, also stimulated stem elongation during warm temperatures. However, when shade and increased temperatures were combined, this factor no longer played an important role.

“We were surprised to find that PIF4 did not play a major role because prior studies have shown the importance of this factor in related growth situations,” says first author Yogev Burko, a Salk staff researcher and assistant professor at the Agriculture Research Organization at the Volcani Institute in Israel. “The fact that PIF7 is the dominant driving force behind this plant growth was a real surprise. With this new knowledge, we hope to fine-tune this growth response in different crop plants to help them adapt to climate change.”

The researchers believe that there is another player, yet to be discovered, that is boosting the effect of PIF7 and auxin. They hope to explore this unknown factor in future studies. Burko’s lab will also be studying how this pathway can be optimized in crop plants.

“Global temperatures are increasing, so we need food crops that can thrive in these new conditions,” says Chory, who co-directs Salk’s Harnessing Plants Initiative and holds the Howard H. and Maryam R. Newman Chair in Plant Biology. “We’ve identified key factors that regulate plant growth during warm temperatures, which will help us to develop better-performing crops to feed future generations.”

Other authors included Björn Christopher Willige and Adam Seluzicki of Salk; Ondřej Novák of Palacký University and Institute of Experimental Botany at The Czech Academy of Sciences; and Karin Ljung of the Swedish University of Agricultural Sciences.

The work was funded by the National Institutes of Health (5R35GM122604-05_05), Howard Hughes Medical Institute, Knut and Alice Wallenberg Foundation (KAW 2016.0341 and KAW 2016.0352), Swedish Governmental Agency for Innovation Systems (VINNOVA 2016-00504), EMBO Fellowships (ALTF 785-2013 and ALTF 1514-2012), BARD (FI-488-13), Human Frontier Science Program (LT000222/2013-L) and Salk’s Pioneer Postdoctoral Endowment Fund.

About the Salk Institute for Biological Studies:

Every cure has a starting point. The Salk Institute embodies Jonas Salk’s mission to dare to make dreams into reality. Its internationally renowned and award-winning scientists explore the very foundations of life, seeking new understandings in neuroscience, genetics, immunology, plant biology and more. The Institute is an independent nonprofit organization and architectural landmark: small by choice, intimate by nature and fearless in the face of any challenge. Be it cancer or Alzheimer’s, aging or diabetes, Salk is where cures begin. Learn more at salk.edu.

JOURNAL

Nature Communications

DOI

10.1038/s41467-022-32585-6 

ARTICLE TITLE

PIF7 is a master regulator of thermomorphogenesis in shade

ARTICLE PUBLICATION DATE

29-Aug-2022

Chinese scientists reported the thermophysical properties of lunar farside regolith with the first in-situ temperature measurement by Chang’E-4 mission

Peer-Reviewed Publication

SCIENCE CHINA PRESS

 

IMAGE: (A) THE COLORED SCATTER PLOTS REPRESENT THE REGOLITH TEMPERATURE MEASUREMENT BY THE CE-4 TEMPERATURE PROBES. (B) THE TEMPERATURE MEASURED NEAR THE LUNAR NOON. view more 

CREDIT: ©SCIENCE CHINA PRESS

Lunar regolith is a layer of loosely-packed rocky grains deposited on the lunar surface, whose physical and chemical properties are important for deciphering the geologic history and lunar spacecraft design. Probing the thermal conductivity of the lunar regolith has drawn a lot of attention since the Apollo era. Early measurements focused on the Apollo regolith samples, but the experimental data were available only at a few landing sites at the nearside.

The CE-4 spacecraft landed at 45.4446°S, 177.5991°E, on the floor of Von Kármán crater, on January 3rd, 2019. After landing, the Yutu-2 rover was released via the deployed two rails. Four temperature probes beneath the terminals of the rails began to measure the temperature of the local regolith every 900 seconds. “It was awesome to have contact temperature measurements of the far side regolith for the first time (Figure 1)”, says Dr. Jun Huang from China University of Geosciences in Wuhan, one of the leaders of this study.

The team found the particle size of the lunar regolith at the CE-4 landing site to be ~15 μm on average over depth, which indicates an immature regolith below the surface. In addition, the conductive component of thermal conductivity is measured as ~1.53×10-3 W m-1 K-1 on the surface and ~8.48×10-3 W m-1 K-1 at 1-m depth. The average bulk density is ~471 kg m-3 on the surface and ~824 kg m-3 in the upper 30 cm of lunar regolith (Figure 2).

“These results will provide important additional ‘ground truth’ for the future analysis and interpretation of global temperature observations. It will also shed lights on the design for future in-situ temperature and heat flux probes” Huang says.

Mr. Xiao Xiao, a PhD candidate at China University of Geosciences, and Dr. Shuoran Yu from Macau University of Science and Technology, together with Dr. Jun Huang, made the plan to analyze the temperature measurements. The study lasted over 2 years from 2020, interrupted several times by the Covid pandemic. “It was a difficult time to build the thermal model, but I enjoyed it,” says Xiao. It is very time-consuming to run the thermal model even with the high-performance cluster in Planetary Science Institute of China University of Geosciences, Wuhan.

Xiao and Yu processed the data and carried out the thermophysical modelling. Ms. He Zhang is the Executive Director of the Chang’E-4 (CE-4) mission and Dr. Youwei Zhang is the principal investigator of the temperature measurement system. Ms. Zhang and Dr. Zhang provide the temperature data and important information of the temperature probes. All the authors contributed to the writing of the manuscript.

CAPTION

(a) The minimum, average and maximum temperature profile from the surface to the depth of 1 m with a surface pressure of 80 Pa. (b) The bulk density profile from the surface to the depth of 1 m corresponding to the minimum, average and maximum temperature in (a) without surface pressure. (c) The conductive component of thermal conductivity profile from the surface to the depth of 1 m corresponding to the minimum, average and maximum temperature in (a) without surface pressure.

CREDIT

©Science China Press

See the article:

Thermophysical properties of the regolith on the lunar farside revealed by the in-situ temperature probing of Chang’E-4 mission

https://doi.org/10.1093/nsr/nwac175

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JOURNAL

National Science Review

DOI

10.1093/nsr/nwac175 

Discovery of the oldest visible planetary nebula hosted by a 500 million year old galactic cluster – a rare beauty with a hot blue heart

Peer-Reviewed Publication

THE UNIVERSITY OF HONG KONG

 

IMAGE: A CONTRAST ENHANCED 30°Ø30 ARCMINUTE QUOTIENT (HΑ−R BAND) IPHAS (DREW ET AL. 2005) MOSAIC CENTRED ON THE CORE OF GALACTIC OPEN CLUSTER M 37 (NGC 2099). THE LOW SURFACE BRIGHTNESS BIPOLAR PN (IPHASX J055226.2+323724) IS ENCOMPASSED BY A RED CIRCLE WITH A DIAMETER OF 445 X 10 ARCSECONDS (THE NEBULAR MAJOR AXIS) WHILE THE BLUE CIRCLE INDICATES THE FULL ∼ 30 ARCMINUTE EXTENT OF THE CLUSTER. THE PN IS WELL WITHIN THE CLUSTER TIDAL RADIUS WITH THE BLUE CSPN AT ALMOST THE PRECISE GEOMETRIC CENTRE OF THE PN. THE CSPN IS ITSELF ONLY ∼280 ARCSECONDS FROM THE PUBLISHED CLUSTER CENTER POSITION. view more 

CREDIT: THE UNIVERSITY OF HONG KONG

An international team of astronomers led by members of the Laboratory for Space Research (LSR) and Department of Physics at The University of Hong Kong (HKU), have discovered a rare celestial jewel–a so-called Planetary Nebula (PN) inside a 500 million-year-old Galactic Open Cluster (OC) called M37 (also known as NGC2099). This is a very rare finding of high astrophysical value. Their findings have just been published in the prestigious open-access paper Astrophysical Journal Letters.

PNe are the ejected, glowing shrouds of dying stars that shine with a rich emission line spectrum and display, as a result, their distinct colours and shapes that make them photogenic magnets for public interest. It was no coincidence that one of the first James Webb Space Telescope (the largest optical telescope in space) images released to the public was a PN!

The PN, with the rather ungainly name of “IPHASX J055226.2+323724”, is only the 3rd example of an association between a PN and an OC out of the ~4,000 PNe known in our Galaxy. It also appears to be the oldest PN ever found. The small team led by Professor Quentin PARKER, Director of the HKU LSR, have determined some interesting properties for their discovery: the authors found the PN has a “kinematic age” of 70,000 years. This estimate is based on how fast the nebula is expanding, as determined from the PN emission lines, and assuming this speed has remained effectively the same since the beginning, and is the time elapsed since the nebular shell was first ejected by the host, a dying star. This compares to typical PN ages of 5,000-25,000 years. It is truly a grand old dame in PN terms but of course a mere “blink of the eye” in terms of the life of the original star itself that runs to hundreds of millions of years.

Because this “grand old dame” lives in a stellar cluster, this environment enables the team to determine powerful additional parameters not possible for the general Galactic PN population. These include estimating the mass of the PN’s progenitor star when it turned off the stellar main sequence, as derived from the observed properties of the thousands of stars in the cluster when plotted in a so-called colour-magnitude diagram. The team can also estimate the residual mass of the central star that ejected the PNe via theoretical isochrones and observed properties of the hot, blue central star. As a result, they figured how massive the star was that ejected the PN gaseous shell when it was born and how much mass is now left in its residual, contracting hot core (which is already a so-called ‘White Dwarf’ star). Fresh “Gaia” data for the hot blue, PN central star also provide a good distance estimate allowing the PN’s actual size at this extreme age to be determined as 3.2pc (parsec, an astronomical unit of measure for interstellar space with 1pc equals to 3.26 light-years) in diameter – unsurprisingly perhaps also at the extreme end of known PN physical sizes.

Former HKU PhD student Dr Vasiliki FRAGKOU, the first author of the study stated, “I am so excited to be able to work on these fascinating rare cases of OC-PN associations because they keep turning up important science results, like all three cases we have found are butterfly (bi-polar) PN in terms of shape, all are very faint and highly evolved, and all have Type-I chemistry according to their emission lines, and of course all have intermediate to high progenitor masses.”

Corresponding author Professor Quentin Parker said, “This is only the third example of a PN found in a Galactic open star cluster, and my group has found all three confirmed examples. They are incredibly rare but also very important as these beautiful objects allow us to independently determine points on the so called initial to final mass relation (IFMR) for stars – an important astrophysical relation –  independent of the traditional method of using white dwarfs in clusters.  Intriguingly, all our points lie just below the empirical IFMR trend currently established but add to the “kink” in this relation found recently in the 2-3 Solar mass range for the original progenitor mass by Marigo et al in the Nature Astronomy journal. Our OC-PN points fortuitously are found in currently sparsely populated regions of the IFMR, making them even more valuable.”

Co-author Professor Albert ZILJSTRA, Hung Hing Ying Distinguished Visiting Professor in Science and Technology at HKU LSR from the University of Manchester commented on the PN visibility lifetimes which have previously been much shorter in the general Galaxy. “This new result implies that the location of a PN in an OC provides an environment suitable for allowing the PNe to expand and fade without disruption by the ambient ISM (which is typically much weaker in an OC) and not as would be the case in the Galaxy.”

The journal paper can be access from here: https://doi.org/10.3847/2041-8213/ac88c1.

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CAPTION

Fig. 2a left panel: An enhanced 6.5 x.5 arcminute colour-composite RGB image of PN IPHASX J055226.2+323724 from the IPHAS survey (Drew et al. 2005) that we confirm as a physical member of the Galactic open cluster M37. Red = Hα, Green = broad band red and Blue = broad band ‘i’. The CSPN is circled in blue; Fig. 2b right panel: 190 x145 arcsecond RGB image created from SDSS with red = i, green = r and blue = g-band. These data clearly shows the faint CSPN (arrowed) at the centre. North is top and East is to the left in both images.

CREDIT

The University of Hong Kong

CAPTION

A combined 1-d continuum subtracted example PN spectrum from March 4th 2022 for IFU pointings a, b, c and d from the paper. The 5 visible PN emission lines are labeled.

CREDIT

The University of Hong Kong

CAPTION

Cluster Gaia DR3 CMD (B versus B-R) diagram fitted with a Padova theoretical isochrone (Bressan et al. (2012), Marigo et al. (2013) for adopted cluster parameters (age = 470 +/- 50 Myrs, reddening E(B−V ) = 0.26 +/-0.04, distance = 1.49 +/- 0.13 kpc and metallicity [Fe/H] = 0.03 +/- 0.28). The CSPN is indicated by the red filled symbol. Stars with >80% probability (Cantat-Gaudin et al. 2018) of being a cluster member, where cross-correlated with Gaia DR3 and are plotted as green dots. The CMD includes all stars with pmRA =0 to 4 and pmDec = −8 to −2 mas/yr (most probable cluster members based on mean proper motions) within 15 arcminutes from the cluster’s apparent center.

CREDIT

The University of Hong Kong

CAPTION

A plot from the known sample of cluster white dwarfs for the latest IFMR estimates and semi-empirical ‘PARSEC’ fit (Cummings et al. 2018) together with our estimated point for PN IPHAS J055226.2+323724 plotted as a red circle. The other two points from known open-cluster PNe are plotted as a yellow circle (PHR 1315-6555 (Fragkou et al. 2019a) and (Parker et al. 2011)) and green circle (BMP J1613-5406 - Fragkou et al. (2019c)). The errors attached to our point reflect the errors in the adopted cluster parameters and the spread of the estimated central-star magnitudes.

CREDIT

The University of Hong Kong

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JOURNAL

The Astrophysical Journal Letters

DOI

10.3847/2041-8213/ac88c1 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

The Planetary Nebula in the 500 Myr Old Open Cluster M37