探花直播 of Cambridge - Chinese Academy of Sciences

Microscopic view on asteroid collisions could help us understand planet formation

cmm201 — Thu, 24 Feb 2022 10:00:43 +0000

A team of researchers, led by the 探花直播 of Cambridge, combined dating and microscopic analysis of the Chelyabinsk meteorite 鈥� which fell to Earth and hit the headlines in 2013 鈥� to get more accurate constraints on the timing of ancient impact events.

Their study, published in Communications Earth & Environment, looked at how minerals within the meteorite were damaged by different impacts over time, meaning they could identify the biggest and oldest events that may have been involved in planetary formation.

鈥淢eteorite impact ages are often controversial: our work shows that we need to draw on multiple lines of evidence to be more certain about impact histories 鈥� almost like investigating an ancient crime scene,鈥� said Craig Walton, who led the research and is based at Cambridge鈥檚 Department of Earth Sciences.

Early in our Solar System鈥檚 history, planets including the Earth formed from massive collisions between asteroids and even bigger bodies, called proto-planets.

鈥淓vidence of these impacts is so old that it has been lost on the planets 鈥� Earth, in particular, has a short memory because surface rocks are continually recycled by plate tectonics,鈥� said co-author Dr Oli Shorttle, who is based jointly at Cambridge鈥檚 Department of Earth Sciences and Institute of Astronomy.

Asteroids, and their fragments that fall to Earth as meteorites, are in contrast inert, cold and much older鈥� making them faithful timekeepers of collisions.

探花直播new research, which was a collaboration with researchers from the Chinese Academy of Sciences and the Open 探花直播, recorded how phosphate minerals inside the Chelyabinsk meteorite were shattered to varying degrees in order to piece together a collision history.

Their aim was to corroborate uranium-lead dating of the meteorite, which looks at the time elapsed for one isotope to decay to another.

鈥� 探花直播phosphates in most primitive meteorites are fantastic targets for dating the shock events experienced by the meteorites on their parent bodies,鈥� said Dr Sen Hu, who carried out the uranium-lead dating at Beijing鈥檚 Institute of Geology and Geophysics, Chinese Academy of Sciences.

Previous dating of this meteorite has revealed two impact ages, one older, roughly 4.5-billion-year-old collision and another which occurred within the last 50 million years.

But these ages aren鈥檛 so clear-cut. Much like a painting fading over time, successive collisions can obscure a once clear picture, leading to uncertainty among the scientific community over the age and even the number of impacts recorded.

探花直播new study put the collisions recorded by the Chelyabinsk meteorite in time order by linking new uranium-lead ages on the meteorite to microscopic evidence for collision-induced heating seen inside their crystal structures. These microscopic clues build up in the minerals with each successive impact, meaning the collisions can be distinguished, put in time order and dated.

Their findings show that minerals containing the imprint of the oldest collision were either shattered into many smaller crystals at high temperatures or strongly deformed at high pressures.

探花直播team also described some mineral grains in the meteorite that were fractured by a lesser impact, at lower pressures and temperatures, and which record a much more recent age of less than 50 million years. They suggest this impact probably chipped the Chelyabinsk meteorite off its host asteroid and sent it hurtling to Earth.

Taken together, this supports a two-stage collision history. 鈥� 探花直播question for us was whether these dates could be trusted, could we tie these impacts to evidence of superheating from an impact?鈥� said Walton. 鈥淲hat we鈥檝e shown is that the mineralogical context for dating is really important.鈥�

Scientists are particularly interested in the date of the 4.5-billion-year-old impact because this is about the time we think the Earth-Moon system came to being, probably as a result of two planetary bodies colliding.

探花直播Chelyabinsk meteorite belongs to a group of so-called stony meteorites, all of which contain highly shattered and remelted material roughly coincident with this colossal impact.

探花直播newly acquired dates support previous suggestions that many asteroids experienced high energy collisions between 4.48 鈥� 4.44 billion years ago. 鈥� 探花直播fact that all of these asteroids record intense melting at this time might indicate Solar System re-organisation, either resulting from the Earth-Moon formation or perhaps the orbital movements of giant planets.鈥�

Walton now plans to refine dating over the window of the Moon-forming impact, which could tell us how our own planet came to being.

聽

Reference:
Walton, C.R. et al. 鈥�Ancient and recent collisions revealed by phosphate minerals in the Chelyabinsk meteorite.鈥� Communications Earth & Environment (2022). DOI: 10.1038/s43247-022-00373-1

A new way of dating collisions between asteroids and planetary bodies throughout our Solar System鈥檚 history could help scientists reconstruct how and when planets were born.

Our work shows that we need to draw on multiple lines of evidence to be more certain about impact histories 鈥� almost like investigating an ancient crime scene

Craig Walton

False-colour image of impact recrystallised phosphate mineral in Chelyabinsk meteorite

探花直播text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright 漏探花直播 of Cambridge and licensors/contributors as identified.聽 All rights reserved. We make our image and video content available in a number of ways 鈥� as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Easy-to-make, ultra-low-power electronics could charge out of thin air

Anonymous — Tue, 13 Oct 2020 11:25:02 +0000

Electronics that consume tiny amounts of power are key for the development of the Internet of Things, in which everyday objects are connected to the internet. Many emerging technologies, from wearables to healthcare devices to smart homes and smart cities, need cost-effective transistors and electronic circuits that can function with minimal energy use.

Printed electronics are a simple and inexpensive way to manufacture electronics that could pave the way for low-cost electronic devices on unconventional substrates 鈥� such as clothes, plastic wrap or paper 鈥� and provide everyday objects with 鈥榠ntelligence鈥�.

However, these devices need to operate with low energy and power consumption to be useful for real-world applications. Although printing techniques have advanced considerably, power consumption has remained a challenge 鈥� the different solutions available were too complex for commercial production.

Now, researchers from the 探花直播 of Cambridge, working with collaborators from China and Saudi Arabia, have developed an approach for printed electronics that could be used to make low-cost devices that recharge out of thin air. Even the ambient radio signals that surround us would be enough to power them. Their results are published in the journal ACS Nano.

Since the commercial batteries which power many devices have limited lifetimes and negative environmental impacts, researchers are developing electronics that can operate autonomously with ultra-low levels of energy.

探花直播technology developed by the researchers delivers high-performance electronic circuits based on thin-film transistors which are 鈥榓mbipolar鈥� as they use only one semiconducting material to transport both negative and positive electric charges in their channels, in a region of operation called 鈥榙eep subthreshold鈥� 鈥� a phrase that essentially means that the transistors are operated in a region that is conventionally regarded as their 鈥榦ff鈥� state. 探花直播team coined the phrase 鈥榙eep-subthreshold ambipolar鈥� to refer to unprecedented ultra-low operating voltages and power consumption levels.

If electronic circuits made of these devices were to be powered by a standard AA battery, the researchers say it would be possible that they could run for millions of years uninterrupted.

探花直播team, which included researchers from Soochow 探花直播, the Chinese Academy of Sciences, ShanghaiTech 探花直播, and King Abdullah 探花直播 of Science and Technology (KAUST),聽used printed carbon nanotubes 鈥� ultra-thin cylinders of carbon 鈥� as an ambipolar semiconductor to achieve the result.

鈥淭hanks to deep-subthreshold ambipolar approach, we created printed electronics that meet the power and voltage requirements of real-world applications, and opened up opportunities for remote sensing and 鈥榩lace-and-forget鈥� devices that can operate without batteries for their entire lifetime,鈥� said co-lead author Luigi Occhipinti from Cambridge鈥檚 Department of Engineering. 鈥淐rucially, our ultra-low-power printed electronics are simple and cost-effective to manufacture and overcome long-standing hurdles in the field.鈥�

鈥淥ur approach to printed electronics could be scaled up to make inexpensive battery-less devices that could harvest energy from the environment, such as sunlight or omnipresent ambient electromagnetic waves, like those created by our mobile phones and wifi stations,鈥� said co-lead author Professor Vincenzo Pecunia from Soochow 探花直播. Pecunia is a former PhD student and postdoctoral researcher at Cambridge鈥檚 Cavendish Laboratory.

探花直播work paves the way for a new generation of self-powered electronics for biomedical applications, smart homes, infrastructure monitoring, and the exponentially-growing Internet of Things device ecosystem.

探花直播research was funded in part by the Engineering and Physical Sciences Research Council (EPSRC).

Reference:
L. Portilla et al. 鈥�Ambipolar Deep-Subthreshold Printed-Carbon-Nanotube Transistors for Ultralow-Voltage and Ultralow-Power Electronics.鈥� ACS Nano (2020). DOI: 10.1021/acsnano.0c06619

Researchers have developed a new approach to printed electronics that allows ultra-low-power electronic devices which聽could recharge from ambient light or radiofrequency noise. 探花直播approach paves the way for low-cost printed electronics that could be seamlessly embedded in everyday objects and environments.

Luis Portilla

Artist's impression of a hybrid-nanodielectric-based printed-CNT transistor

Yes

Chinese cave 鈥榞raffiti鈥� tells a 500-year story of climate change and impact on society

sc604 — Thu, 13 Aug 2015 13:00:00 +0000

An international team of researchers, including scientists from the 探花直播 of Cambridge, has discovered unique 鈥榞raffiti鈥� on the walls of a cave in central China, which describes the effects drought had on the local population over the past 500 years.

探花直播information contained in the inscriptions, combined with detailed chemical analysis of stalagmites in the cave, together paint an intriguing picture of how societies are affected by droughts over time: the first time that it has been possible to conduct an in situ comparison of historical and geological records from the same cave. 探花直播results, published in the journal Scientific Reports, also point to potentially greatly reduced rainfall in the region in the near future, underlying the importance of implementing strategies to deal with a world where droughts are more common.

探花直播inscriptions were found on the walls of Dayu Cave in the Qinling Mountains of central China, and describe the impacts of seven drought events between 1520 and 1920. 探花直播climate in the area around the cave is dominated by the summer monsoon, in which about 70% of the year鈥檚 rain falls during a few months, so when the monsoon is late or early, too short or too long, it has a major impact on the region鈥檚 ecosystem.

鈥淚n addition to the obvious impact of droughts, they have also been linked to the downfall of cultures 鈥� when people don鈥檛 have enough water, hardship is inevitable and conflict arises,鈥� said Dr Sebastian Breitenbach of Cambridge鈥檚 Department of Earth Sciences, one of the paper鈥檚 co-authors. 鈥淚n the past decade, records found in caves and lakes have shown a possible link between climate change and the demise of several Chinese dynasties during the last 1800 years, such as the Tang, Yuan and Ming Dynasties.鈥�

According to the inscriptions in Dayu Cave, residents would come to the cave both to get water and to pray for rain in times of drought. An inscription from 1891 reads, 鈥淥n May 24^th, 17^th year of the Emperor Guangxu period, Qing Dynasty, the local mayor, Huaizong Zhu led more than 200 people into the cave to get water. A fortune-teller named Zhenrong Ran prayed for rain during the ceremony.鈥�

Another inscription from 1528 reads, 鈥淒rought occurred in the 7^th year of the Emperor Jiajing period, Ming Dynasty. Gui Jiang and Sishan Jiang came to Da鈥檃n town to acknowledge the Dragon Lake inside in Dayu Cave.鈥�

While the inscriptions are business-like in tone, the droughts of the 1890s led to severe starvation and triggered local social instability, which eventually resulted in a fierce conflict between government and civilians in 1900. 探花直播drought in 1528 also led to widespread starvation, and there were even reports of cannibalism.

鈥淭here are examples of things like human remains, tools and pottery being found in caves, but it鈥檚 exceptional to find something like these dated inscriptions,鈥� said Dr Liangcheng Tan of the Institute of Earth Environment at the Chinese Academy of Sciences in Xi鈥檃n, and the paper鈥檚 lead author. 鈥淐ombined with the evidence found in the physical formations in the cave, the inscriptions were a crucial way for us to confirm the link between climate and the geochemical record in the cave, and the effect that drought has on a landscape.鈥�

探花直播researchers removed sections of cave formations, or speleothems, and analysed the stable isotopes and trace elements contained within. They found that concentrations of certain elements were strongly correlated to periods of drought, which could then be verified by cross-referencing the chemical profile of the cave with the writing on the walls.

When cut open, speleothems such as stalagmites frequently reveal a series of layers that record their annual growth, just like tree rings. Using mass spectrometry, the researchers analysed and dated the ratios of the stable isotopes of oxygen, carbon, as well as concentrations of uranium and other elements. Changes in climate, moisture levels and surrounding vegetation all affect these elements, since the water seeping into the cave is related to the water on the surface. 探花直播researchers found that higher oxygen and carbon isotope ratios, in particular, corresponded with lower rainfall levels, and vice versa.

探花直播researchers then used their results to construct a model of future precipitation in the region, starting in 1982. Their model correlated with a drought that occurred in the 1990s and suggests another drought in the late 2030s. 探花直播observed droughts also correspond with the El Ni帽o-Southern Oscillation (ENSO) cycle. Due to the likelihood that climate change caused by humans will make ENSO events more severe, the region may be in for more serious droughts in the future.

鈥淪ince the Qinling Mountains are the main recharge area of two larger water transfer projects, and the habitat for many endangered species, including the iconic giant panda, it is imperative to explore how the region can adapt to declining rain levels or drought,鈥� said Breitenbach. 鈥淭hings in the world are different from when these cave inscriptions are written, but we鈥檙e still vulnerable to these events 鈥� especially in the developing world.鈥澛�

Reference:
Tan, L. et al. A Chinese cave links climate change, social impacts, and human adaptation over the last 500 years. Scientific Reports (2015). DOI: 10.1038/srep12284.聽

Unique inscriptions found in a cave in China, combined with chemical analysis of cave formations, show how droughts affected the local population over the past five centuries, and underline the importance of implementing strategies to deal with climate change in the coming years.

When people don鈥檛 have enough water, hardship is inevitable and conflict arises

Sebastian Breitenbach

L. Tan

Inscription from 1891 found in Dayu Cave

探花直播text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes