Saturday, April 15, 2023

Will ChatGPT replace computational materials scientists?

Peer-Reviewed Publication

BEIJING INSTITUTE OF TECHNOLOGY PRESS CO., LTD

ChatGPT for Computational Materials Science 

IMAGE: SCIENTISTS FROM ZHEJIANG UNIVERSITY DISCUSSED THE POTENTIAL APPLICATIONS OF CHATGPT IN COMPUTATIONAL MATERIALS SCIENCE view more 

CREDIT: [LIZHE HU & ZIJIAN HONG, ZHEJIANG UNIVERSITY]

“ChatGPT is a very impressive tool,” said paper author Zijian Hong, professor at the School of Materials Science and Engineering, Zhejiang University, China. “As a computational materials scientist, I’m always eager to embrace new tools, in particular, new tools in computer science and AI. Since the born of the new ChatGPT, I’m just wondering whether such a tool can assist us in computational materials science”

Hong explained that for a computational materials task, there are three main steps: building a model or a structure, writing codes for specific scientific software, and preparing data visualization scripts. To test the capability of ChatGPT, he examined it from these aspects.

“ChatGPT can help us prepare scripts to build atomic structure, i.e., the cif file, scripts for running a DFT calculation, and scripts for data visualization”, Hong said. “At least it is trying to help us from chat, although the scripts are not working at all when I accessed on Feb. 20, 2023.”

“But what surprised me is the ability to evolve and learn from communications”, Hong added, “When I accessed 20 days later, it gives me different answers, towards the correct answer. And if I give more hints, such as the correct lattice structure, it can correct by itself, just like a human being.”

“It is still not perfect for sure. For example, it still makes simple mistakes, the consistency of the output is not guaranteed, and the ethical concerns are still there.” Hong said. “But change is really near the corner, for computational materials science. We should embrace it rather than avoid it.”

This work is supported by the Fundamental Research Funds for the Central Universities and a startup fund from Zhejiang University.

GEN-Z-CRYPTO CRIMINAL CAPITALI$M

FTX bosses joked about losing millions of dollars, damning report claims


Oliver Gill
Mon, 10 April 2023 

SBF - David Dee Delgado/Reuters

FTX bosses joked about losing tens of millions of dollars and signed off expenses with emojis, according to a damning official filing into the crypto exchange's collapse.

Founder Sam Bankman-Fried and senior executives are accused of “hubris, incompetence, and greed” in a 39-page report published by FTX's restructuring experts.

A tight-knit group of individuals “stifled dissent, commingled and misused corporate and customer funds, lied to third parties about their business, joked internally about their tendency to lose track of millions of dollars in assets”, the report found.


It said that Mr Bankman-Fried claimed FTX's trading arm Alameda Research was “hilariously beyond any threshold of any auditor being able to even get partially through an audit”

According to the report, Mr Bankman-Fried said: “Alameda is unauditable. I don’t mean this in the sense of ‘a major accounting firm will have reservations about auditing it’; I mean this in the sense of ‘we are only able to ballpark what its balances are, let alone something like a comprehensive transaction history.’

“We sometimes find $50m of assets lying around that we lost track of; such is life.”

The report goes on to reveal that money transfers were not properly documented.

It said: “To make matters worse, Slack, Signal, and other informal methods of communication were frequently used to document approvals. Signal and Telegram were at times utilised in communications with both internal and external parties with “disappearing messages” enabled, rendering any historical review impossible.

“Expenses and invoices of the FTX Group were submitted on Slack and were approved by ‘emoji.’ These informal, ephemeral messaging systems were used to procure approvals for transfers in the tens of millions of dollars, leaving only informal records of such transfers, or no records at all.”

Veteran restructuring executive John J. Ray III, who ran the insolvency of Enron two decades ago, is overseeing FTX’s bankruptcy proceedings.

Mr Ray’s “first interim report” includes the findings of more than one million company documents and 19 employee interviews.

Mr Ray said: “We are releasing the first report in the spirit of transparency that we promised since the beginning of the Chapter 11 process.”

FTX collapsed last November after analysts raised questions about its solvency.

As Mr Bankman-Fried’s empire imploded, further questions about alleged wrongdoing have been raised.

He has been charged with fraud and breaches of campaign-finance law and after pleading not guilty is due to face trial in November.

The debtors’ report found that FTX was operated at the most senior level by Mr Bankman-Fried, minority shareholder Gary Wang, and Nishad Singh, who joined from Alameda.

Mr Singh pleaded guilty in February to fraud as part of a cooperation deal with prosecutors.

Mr Wang and Caroline Ellison, Mr Bankman-Fried ex-girlfriend and former chief executive of Alameda, pleaded guilty last year to charges in connection to their roles at FTX and Alameda Research and are working with the US government.
David Attenborough’s online Wild Isles isn’t too hard-hitting for TV – it doesn’t go far enough

Dave Goulson
Mon, 10 April 2023 


It was with some trepidation that I began viewing the online-only episode of David Attenborough’s latest documentary series, Wild Isles. The episode, Saving Our Wild Isles, focuses on the threats facing British wildlife and those fighting to save it.

Rumours had abounded that the BBC dared not broadcast this final episode on television because it was too hard-hitting, with some suggesting it was too critical of government action or inaction. I braced myself, expecting images of rivers polluted with plastics, sewage and pesticides, tales of dwindling numbers of insects, birds and mammals, of ancient woodlands destroyed, overfished seas, mature urban trees felled, meadows ploughed, raptors such as golden eagles poisoned, the climate crisis running amok.

I need not have worried. Although there was passing mention of some awfully depressing statistics, the film is deliberately uplifting and overwhelmingly positive. It focuses on heartwarming projects that are restoring nature, from the London docklands to the arable fields of East Anglia, and north to the wilds of Cairngorm. These examples show that people benefit from and need nature, and that we can all get involved in protecting it.

I recommend that you watch it, but I worry.

We face an existential crisis. Those of us who have been on this planet for half a century or more have lived through the greatest loss of wildlife on our planet for 65m years, since a meteor wiped out the dinosaurs. Climate breakdown is accelerating. Our civilisation, our children’s health and wellbeing, and the future of much of the life that remains on our planet, hangs in the balance.

For at least 30 years it has been painfully obvious that we are heading for disaster, yet our response has been woefully inadequate. Successive governments have abjectly failed to grasp the importance of the threat we face. There have always been wonderful people swimming against the tide, defending the environment, but they are far too few.

Watching Saving Our Wild Isles, you might imagine that the tide is finally turning. It isn’t.

Recently, our government ignored the advice of its own scientific committee and granted a derogation allowing sugar beet farmers to use a banned neonicotinoid pesticide. Just last month it pushed back proposed bans on horticultural use of peat – a vital store of carbon that is extracted from a rare and biodiverse habitat – until 2030. Much needed reintroductions of missing species such as beavers are blocked or delayed.

The new farming subsidy known as environmental land management schemes (ELMs), which seemed quite promising when first announced, has been stalled, watered-down and botched in implementation such that most farmers have been left feeling bewildered and unsupported. Oil and gas exploration are being encouraged, and a new coalmine opened. Raw sewage is being dumped into England’s rivers on average 800 times a day. Environmental legislation inherited from Europe is being torched. Without support from government, the actions of a few individuals fighting for nature will never be enough.

Environmentalists have been saying “it is not yet too late” for a long time. In reality it is already too late to avoid much worse damage than we have already seen, and whatever we do now the climate crisis will continue to worsen.

Saving Our Wild Isles is charming, and perhaps it will inspire a few more people to do more for nature, but I was hoping for something different, something that might really wake us up to the dismal state of our country.

David Attenborough is a hero to many of us, and no one has done more to champion the wonders of our natural world. Perhaps he might yet persuade the BBC to commission the hard-hitting, kick-up-the-arse documentary we really need.

Dave Goulson is a professor of biology at the University of Sussex, where he specialises in bee ecology
UK spent almost £500,000 on unused support scheme for energy firms

Alex Lawson
THE GUARDIAN

Photograph: Andrew Milligan/PA

The Treasury spent almost half a million pounds on an unused emergency scheme for energy traders launched by Liz Truss that was quietly closed earlier this year.

The energy markets financing scheme (EMFS) was devised by the Treasury and the Bank of England as a £40bn government-guaranteed backstop fund to provide stability for energy and financial markets.

The scheme was designed to offer energy traders liquidity to deal with massive margin calls – demands from brokers to deposit further cash or securities to cover possible losses – but was shut in January as a sharp fall in wholesale gas prices earlier this year eased pressure on energy firms.

In response to a freedom of information request by the Guardian, the Treasury said it spent £465,000 on “external technical consultants to support the creation of the EMFS”.

It said that 11 commercial banks and 20 energy firms were invited to technical video calls with the Treasury relating to the scheme. Energy firms would have applied jointly with a bank but no applications were made during a window from October to late January.

FTI Consulting, the global management consultancy, received £400,000 for its advisory role, while the law firm Hogan Lovells received £65,000.

The government contract was originally worth up to £4.9m for FTI to provide market research and consultancy services, according to analysis by the data firm Tussell.

Truss announced the scheme in September as part of a package of measures to prevent the energy crisis causing further damage during the winter. The then prime minister also announced support for households and businesses, both of those schemes were later pared back to reduce the cost.

The Treasury said: “The scheme was introduced as part of a range of contingency measures to support the energy sector.

“Since the launch of the scheme prices in the wholesale gas markets have declined markedly and this has reduced some of the pressure facing eligible energy firms.”

It added: “Due to improvements in market conditions since the launch of the scheme, energy firms were able to access the necessary lines of credit from commercial lenders without the need for the government-backed guarantee.

“The EMFS was designed to supplement existing commercial financing where this alone was not sufficient with penal pricing and conditions upon drawdown set so it would only be used if commercial and competitively priced financing was unavailable on the market. It was not intended to replace commercial lending.”

The Bank of England refused to state how much it spent on its part in the creation of the EMFS.

Industry sources said that strict conditions preventing companies paying bonuses to executives or dividends to shareholders after using the scheme had also deterred energy companies.

The government’s spending on energy support schemes has been under intense scrutiny as households and businesses attempt to cope with the high bills inflated by the gas prices linked to the war in Ukraine.

In his budget, Jeremy Hunt made a U-turn on a plan to make household support less generous but has stuck with a cut in financial energy aid for businesses, which began on 1 April.

The support for firms has been labelled “scattergun” by business groups, which have warned that many are now considering closure in the face of unaffordable bills.

Kate Nicholls, the chief executive of UKHospitality, which represents pubs, restaurants and hotels, said: “The significant reduction in energy support comes as a hammer blow to thousands of hospitality businesses that are already struggling with extortionate energy bills that are already double what they were a year ago.

“This could not come at a worse time as venues continue to also grapple with record food and drink price inflation, which is showing no signs of slowing down.”

Experts examine the safety of probiotics

Scientific group confirms probiotics are generally safe and provides comprehensive guidance on potential probiotic risks

Peer-Reviewed Publication

INTERNATIONAL SCIENTIFIC ASSOCIATION FOR PROBIOTICS AND PREBIOTICS

Scientific evidence assessing the benefits and risks of probiotics continues to accumulate. With new types of probiotics being introduced on the market and healthcare professionals recommending probiotic use in populations other than generally healthy individuals, continual attention to probiotic safety is warranted.

new review by experts in probiotic science considers if emerging evidence raises any new safety concerns for probiotics. The review provides a comprehensive list of potential probiotic risks, along with recommendations for assessing whether a given probiotic product is safe. The 17 experts, specialists in microbiology, food science, pediatrics, family medicine and related fields, were convened by the International Scientific Association for Probiotics and Prebiotics (ISAPP). The experts aimed to provide both scientists and healthcare professionals with guidance on how to assess probiotic safety—including for strains without a history of safe use.

Corresponding author Dr. Mary Ellen Sanders, PhD, says, “While traditional probiotics have a good safety record based on many published clinical trials and history of safe use, not all uses of probiotics are equally safe. This paper emphasizes that probiotics administered to at-risk populations must be fit-for-purpose, which in some cases requires additional safety scrutiny.”

The experts acknowledged in this paper the increased reporting of microbiome data in probiotic studies. A few isolated studies have suggested that certain probiotic preparations may adversely affect the microbiome, through reduction of diversity or hindering microbiome recovery after antibiotics. This review concludes that such observations, while interesting mechanistically, lack evidence of clinical or health-related impact, and therefore do not pose actionable safety concerns.

The authors provide recommendations for addressing possible probiotic risks, including issues specific to probiotic strains, quality of probiotic manufacture, and risks inherent to practices of probiotic administration.  Potential concerns about probiotic safety were considered from both acute and long-term safety perspectives.

First author Prof. Daniel Merenstein, MD, says, “Probiotics have been proven to have efficacy in several indications. But as is the case with every intervention, there is always the potential for harm. Human trials need to do a better job of assessing harm and we hope this article provides current perspective on how to properly do this. Existing literature demonstrates that probiotics have a very good acute safety record. However, like almost all interventions we use in medicine, the long term impact is understudied.”

The authors say for novel probiotics, analyzing the entire genetic makeup of a microorganism is a cornerstone for assessing its safety. Not only does this allow precise strain identification, but it can also illuminate any genes of concern, which may confer toxigenicity, pathogenicity or antibiotic resistance.

The review provides important guidance for healthcare professionals who currently recommend probiotics to their patients, and serves as a call for continued attention to probiotic safety in future scientific studies.

About ISAPP

ISAPP is a nonprofit organization founded in 2002 to advance the science of probiotics and prebiotics, and more recently synbiotics, postbiotics, and fermented foods. ISAPP communicates scientifically accurate information to healthcare providers, scientists, consumers, and regulatory bodies through its many resources. For more information about ISAPP, see www.ISAPPscience.org.

Why did the mpox (monkeypox) epidemic wane? Belgian researchers propose theory

Reports and Proceedings

EUROPEAN SOCIETY OF CLINICAL MICROBIOLOGY AND INFECTIOUS DISEASES

**Note: the release below is from the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID 2023, Copenhagen, 15-18 April)Please credit the conference if you use this story**

Did the recent mpox (formerly known as monkeypox) outbreak end because of “network immunity”?  That’s the theory being put forward by Belgian researchers at this year’s European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) in Copenhagen, Denmark (15-18 April).

2022 saw a global outbreak of mpox, a viral infection that had not previously been documented as having sustained person-to-person transmission outside of Africa. There were more than 85,000 cases worldwide, with men who have sex with men at highest risk.

Cases rose rapidly from May 2022, before starting to decline a few months later. The reasons the outbreak waned are unclear.

Researcher Dr Christophe Van Dijck, of the Institute of Tropical Medicine, Antwerp, Belgium, says: “The rapid rise in cases in May 2022 was likely caused by efficient viral transmission during sexual contact between individuals with high partner turnover in a dense and geographically extended sexual network.

“Insufficient knowledge of the disease as well as asymptomatic and pre-symptomatic transmission may have enhanced disease spreading. “

The subsequent decline in the epidemic after July 2022 remains insufficiently explained. Possible explanations include improved awareness and behavioural change in the population at risk and acquisition of vaccination- or infection-induced immunity.

“However, in most countries including Belgium, the decline in mpox cases had already started before a substantial proportion of the population at risk had been vaccinated.”

Thus, Dr Van Dijck and colleagues hypothesised that the epidemic waned due to a change in the behaviour of the population at risk.

To find out more, they used two sets of data collected at the Institute of Tropical Medicine in 2022. All participants provided informed consent.

The first set of data was from a questionnaire filled in at diagnosis by individuals with mpox.

Among the 155 individuals with mpox, 95.5% were gay and bisexual men who have sex with men (GBMSM) and the median number of sexual partners in the previous three weeks was two.

Individuals diagnosed with mpox at the beginning of the epidemic reported more partners than those later in the epidemic (decline of 0.86 partners per week).

The second set of data was from a questionnaire filled in by men who were attending a clinic at the Institute for pre-exposure prophylaxis (PrEP, a drug that reduces the risk of getting HIV).

For the purposes of the analysis the PrEP users were divided into two groups, core PrEP-users (those with a history of syphilis infection) and non-core PrEP-users (no history of syphilis). A history of syphilis was used as a proxy for more risky sexual behaviour in the past: a person who had syphilis is probably more centrally located in the sexual network than someone who never had syphilis. 

Among 1,322 PrEP-users, 99.6% were GBMSM, of whom 55.9% visited the clinic repeatedly in 2022. At first visit, the median number of sexual partners in the previous three months was five. Core-group PrEP-users reported consistently more partners than non-core-group PrEP-users.

The number of partners in both the core and non-core-groups increased throughout 2022.

Dr Van Dijck says: “The decline in number of partners reported by individuals diagnosed with mpox towards the end of the epidemic suggests a change in behaviour of the population at risk. However, this was not corroborated by data from the PrEP population, where the overall number of sexual partners increased over time.

“Therefore, we propose an alternative hypothesis: core members of the sexual network were infected with mpox first, peripheral members later. Infection-induced immunity of the individuals at the core of the sexual network generated ‘network immunity’ which halted the epidemic.

“We are currently working on serological and modelling studies to establish whether this hypothesis is true.

“In the meantime, we need to be aware that future mpox outbreaks may occur if the ‘network immunity’ is disturbed, for example by waning immunity of infected or vaccinated persons or when previously uninfected, peripheral members of the sexual network become more sexually active.”

Notes to editors:

The authors declare no conflicts of interest.

This press release is based on oral presentation MMK0602 at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) annual meeting. The material has been peer reviewed by the congress selection committee.  There is no full paper at this stage and, because this is an oral presentation, there isn’t a poster

The Lancet Public Health: Hearing aids may protect against a higher risk of dementia associated with hearing loss, study suggests


Peer-Reviewed Publication

THE LANCET

Peer-reviewed / Observational study / People

The Lancet Public Health: Hearing aids may protect against a higher risk of dementia associated with hearing loss, study suggests

  • Study of 437,704 people suggests those experiencing hearing loss and not using hearing aids may have a higher risk of dementia than people without hearing loss. Those using hearing aids did not appear to be at an increased risk of dementia.
  • After adjusting for other factors, study analysis suggests a 1.7% risk of dementia in people with hearing loss who are not using hearing aids, compared to 1.2% among those without hearing loss or who are experiencing hearing loss but using hearing aids. 
  • Authors call for greater public awareness of the potential protective effects of hearing aids against dementia, increased accessibility to hearing aids by reducing cost and more support for primary care workers to screen for hearing impairment, raise awareness, and deliver treatment such as fitting hearing aids. 

People experiencing hearing loss who are not using a hearing aid may have a higher risk of dementia than people without hearing loss, suggests a new study published in The Lancet Public Health journal. However, using a hearing aid may reduce this risk to the same level as people without hearing loss.

Dementia and hearing loss are common conditions among older adults. The Lancet Commission on dementia prevention, intervention, and care, published in 2020, suggested that hearing loss may be linked to around 8% of worldwide dementia cases [1], therefore, addressing hearing impairment could be a crucial way to reduce the global burden of dementia.

“The evidence is building that hearing loss may be the most impactful modifiable risk factor for dementia in mid-life, but the effectiveness of hearing aid use on reducing the risk of dementia in the real world has remained unclear. Our study provides the best evidence to date to suggest that hearing aids could be a minimally invasive, cost-effective treatment to mitigate the potential impact of hearing loss on dementia,” says corresponding author Prof. Dongshan Zhu, Shandong University (China). [2]

The researchers looked at data from 437,704 people who were part of the UK Biobank database [3]. Information on the presence of hearing loss and use of hearing aids was collected via self-reported questionnaires, and dementia diagnoses were determined using hospital records and death register data. The average age of study participant at recruitment was 56 years old, and the average follow-up time was 12 years.

Around three-quarters of the participants (325,882/437,704) had no hearing loss, and the remaining one-quarter (111,822) had some level of hearing loss. Among those with hearing loss, 11.7% (13,092 / 111,822) used hearing aids.

After controlling for other factors, the study suggests that, compared to participants with normal hearing, people with hearing loss not using hearing aids had a 42% higher risk of all-cause dementia, while no increased risk was found in people with hearing loss who used hearing aids. 

This is approximately equivalent to a 1.7% risk of dementia in people with hearing loss who are not using hearing aids, compared to 1.2% among those without hearing loss or who are experiencing hearing loss but using hearing aids.

“Close to four-fifths of people experiencing hearing loss do not use hearing aids in the UK [4]. Hearing loss may begin early in one’s 40s, and there is evidence that gradual cognitive decline before a dementia diagnosis can last 20 to 25 years. Our findings highlight the urgent need for the early introduction of hearing aids when someone starts to experience hearing impairment. A group effort from across society is necessary, including raising awareness of hearing loss and the potential links with dementia, increasing accessibility to hearing aids by reducing cost, and more support for primary care workers to screen for hearing impairment, raise awareness, and deliver treatment such as fitting hearing aids,” says Dongshan Zhu. [2]

The researchers also analysed how other factors, including loneliness, social isolation, and depressive symptoms, might impact the association between hearing loss and dementia. The study analysis suggests that less than 8% of the association between hearing aid use and decreased dementia risk could be removed by improving psychosocial problems. The authors say this indicates the association between hearing aid use and protection from increased dementia is likely mostly due to direct effects from hearing aids rather than the investigated indirect causes.

“The underlying pathways which may link hearing aid use and reduced dementia risk are unclear. Further research is needed to establish a causal relationship and the presence of underlying pathways,” says study author Dr Fan Jiang, Shandong University (China). [2]

The authors acknowledge some limitations to the study, including that self-reporting is at risk of bias and that, as this study is observational, the association between hearing loss and dementia might be due to reverse causation through neurodegeneration or other shared mechanisms. Additionally, although many cofactors were accounted for, there might be unmeasured factors, such as those who used hearing aids potentially also taking more care of their health than those who did not. Lastly, most UK Biobank participants are white, and very few participants were born deaf or experienced hearing loss before acquiring spoken language, which may limit the generalisability of the findings to other ethnicities and people with limited hearing using sign language.

Writing in a Linked Comment, Prof Gill Livingston and Dr Sergi Costafreda, University College London, who were not involved in this research, said: “With the addition of Jiang and colleagues’ work, the evidence that hearing aids are a powerful tool to reduce the risk of dementia in people with hearing loss, is as good as possible without randomised controlled trials, which might not be practically possible or ethical because people with hearing loss should not be stopped from using effective treatments. Dementia is not only an illness that affects the individual and their family but can also be expensive. However, using hearing aids to prevent dementia has been found to be cost-effective and cost-saving. In the USA, hearing aids have become available to purchase over the counter, thus making them more accessible. The evidence is compelling that treating hearing loss is a promising way of reducing dementia risk. This is the time to increase awareness of and detection of hearing loss, as well as the acceptability and usability of hearing aids.”
 

NOTES TO EDITORS

This study was funded by the National Natural Science Foundation of China and Shandong Province, Taishan Scholars Project, China Medical Board and China Postdoctoral Science Foundation. See the Article for a full list of author affiliations. 

The labels have been added to this press release as part of a project run by the Academy of Medical Sciences seeking to improve the communication of evidence. For more information, please see: http://www.sciencemediacentre.org/wp-content/uploads/2018/01/AMS-press-release-labelling-system-GUIDANCE.pdf if you have any questions or feedback, please contact The Lancet press office pressoffice@lancet.com 

[1] https://www.thelancet.com/article/S0140-6736(20)30367-6/fulltext

[2] Quote direct from author and cannot be found in the text of the Article.

[3] https://www.ukbiobank.ac.uk/learn-more-about-uk-biobank/about-us 

[4] https://pubmed.ncbi.nlm.nih.gov/30664127/ 

The labels have been added to this press release as part of a project run by the Academy of Medical Sciences seeking to improve the communication of evidence. For more information, please see: http://www.sciencemediacentre.org/wp-content/uploads/2018/01/AMS-press-release-labelling-system-GUIDANCE.pdf if you have any questions or feedback, please contact The Lancet press office pressoffice@lancet.com  

IF YOU WISH TO PROVIDE A LINK FOR YOUR READERS, PLEASE USE THE FOLLOWING, WHICH WILL GO LIVE AT THE TIME THE EMBARGO LIFTS: https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(23)00048-8/fulltext 

Data can now be processed at the speed of light!

Peer-Reviewed Publication

POHANG UNIVERSITY OF SCIENCE & TECHNOLOGY (POSTECH)

Researchers 

IMAGE: RESEARCHERS view more 

CREDIT: POSTECH

How can Marvel movie character Ant-Man produce such strong energy out of his small body? The secret lies in the “transistors” on his suit that amplify weak signals for processing. Transistors that amplify electrical signals in the conventional way lose heat energy and limit the speed of signal transfer, which degrades performance. What if it were possible to overcome such limitation and make a high-performance suit that is light and small but without loss of heat energy?

A POSTECH team of Professor Kyoung-Duck Park and Yeonjeong Koo from the Department of Physics and a team from ITMO University in Russia led by Professor Vasily Kravtsov jointly developed a “nano-excitonic transistor” using intralayer and interlayer excitons in heterostructure-based semiconductors, which addresses the limitations of existing transistors.

“Excitons” are responsible for light emission of semiconductor materials and are key to developing a next-generation light-emitting element with less heat generation and a light source for quantum information technology due to the free conversion between light and material in their electrically neutral states. There are two types of excitons in a semiconductor heterobilayer, which is a stack of two different semiconductor monolayers: the intralayer excitons with horizontal direction and the interlayer excitons with vertical direction.

Optical signals emitted by the two excitons have different lights, durations, and coherence times. This means that selective control of the two optical signals could enable the development of a two-bit exciton transistor. However, it was challenging to control intra- and interlayer excitons in nano-scale spaces due to the non-homogeneity of semiconductor heterostructures and low luminous efficiency of interlayer excitons in addition to the diffraction limit of light.

The team in its previous research had proposed technology for controlling excitons in nano-level spaces by pressing semiconductor materials with a nano-scale tip. This time, for the first time ever, the researchers were able to remotely control the density and luminance efficiency of excitons based on polarized light on the tip without directly touching the excitons. The most significant advantage of this method, which combines a photonic nanocavity and a spatial light modulator, is that it can reversibly control excitons, minimizing physical damage to the semiconductor material. Also, the nano-excitonic transistor that utilizes “light” can help process massive amounts of data at the speed of light while minimizing heat energy loss.

Artificial intelligence (AI) has made inroads into our lives more quickly than we ever expected, and it requires huge volumes of data for learning in order to provide good answers that are actually helpful for users. The ever-increasing volume of information should be collected and processed as more and more fields utilize AI. This research is expected to propose a new data processing strategy befitting an era of data explosion. Yeonjeong Koo, one of the co-first authors of the research paper, said, “The nano-excitonic transistor is expected to play an integral role in realizing an optical computer, which will help process the huge amounts of data driven by AI technology.

The research, recently published in international journal ACS Nano, was supported by the Samsung Science and Technology Foundation and National Research Foundation of Korea.


Research Image

CREDIT

POSTECH