Friday, April 15, 2022

Your morning coffee could hasten species’ extinction

Richer nations increase species extinction risk in poorer ones, new University of Sydney and IUCN research finds

Peer-Reviewed Publication

UNIVERSITY OF SYDNEY

Nombre de Dios Streamside Frog 

IMAGE: THE US DRIVES 24 PERCENT OF THE EXTINCTION-RISK FOOTPRINT OF THE NOMBRE DE DIOS STREAMSIDE FROG (CRAUGASTOR FECUNDUS), A CRITICALLY ENDANGERED FROG FOUND IN HONDURAS. view more 

CREDIT: JOE TOWNSEND

As negotiations before the 15th Conference of the Parties to the Convention on Biological Diversity (COP-15) take place, international research has quantified the impact of human consumption on species extinction risk.

Around 1 million species already face extinction, many within decades, according to the recent Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) assessment report.

Spanning more than 5,000 species in 188 countries, the research finds consumption in Europe, North America, and East Asia (such as Japan and South Korea) primarily drives species extinction risk in other countries. Affected species include the Nombre de Dios Streamside Frog in Honduras and the Malagasy Giant Jumping Rat in Madagascar.

Published in Nature: Scientific Reports, the research is led by Ms Amanda Irwin at the University of Sydney’s Integrated Sustainability Analysis research group and is co-authored by the International Union for Conservation of Nature (IUCN) chief scientist Dr Thomas Brooks and chief economist Dr Juha Siikamäki.

The authors liken the biodiversity crisis to the climate one, albeit with less publicity. “These crises are occurring in parallel,” Ms Irwin said. “The upcoming COP-15 will hopefully raise the profile of the other human-driven natural crisis of our generation – irreparable biodiversity loss – and our findings can provide valuable insights into the role that global consumption plays as one of the drivers of this loss.”

Key findings

  • Consumption in 76 countries, concentrated in Europe, North America, and East Asia, primarily drives extinction risk in other countries.
  • In 16 countries, concentrated in Africa, this extinction-risk footprint is driven by offshore consumption.
  • In 96 countries – around half of those studied – domestic consumption is the greatest driver of the extinction-risk footprint.
  • International trade drives 29.5 percent of the global extinction-risk footprint.
  • Consumption of products and services from the food, beverage and agriculture sectors is the greatest driver of consumption-driven extinction risk, together constituting 39 percent of the global extinction-risk footprint, followed by consumption of goods and services from the construction sector (16 percent).

PhD candidate Ms Irwin said: “The complexity of economic interactions in our globalised world means that the purchase of a coffee in Sydney may contribute to biodiversity loss in Honduras. The choices we make every day have an impact on the natural world, even if we don’t see this impact.”

“Everything that we consume has been derived from the natural world, with raw materials transformed into finished products through a myriad of supply chain transactions. These transactions often have a direct impact on species.”

Co-author, IUCN chief economist Dr Juha Siikamäki notes: “This insight into how prevalently consumption patterns influence biodiversity loss across the globe is critical to inform ongoing international negotiations for nature, including the 15th Conference of the Parties to the Convention on Biological Diversity, which aims to finalise the post-2020 global biodiversity framework later this year.

“The finding from this study that about 30 percent of the global extinction-risk footprint is embedded in international trade underlines the need to consider the responsibilities of different countries and all actors, including financing of conservation, not only in the context of their national boundaries but extending to their impacts internationally.”

Co-author, Associate Professor Arne Geschke from the Integrated Sustainability Analysis research group at the University of Sydney said: “The activities which threaten species in a given location are often induced by consumption patterns in far-away locations, meaning that local interventions may be insufficient. 

“Appropriate interventions to address extinction risk in Madagascar, for example, where 66 percent of the extinction-risk footprint is exported, should be different from those implemented in Colombia, where 93 percent of the extinction-risk footprint is generated by domestic consumption.”

CAPTION

The extinction risk of the the Malagasy Giant Jumping Rat in Madagascar 

is increased by consumption in other countries.

CREDIT

Josh More.

About the study

Using data available in IUCN’s Red List of Threatened Species, the authors introduced the non-normalised Species Threat Abatement and Restoration (nSTAR) metric as a measure of extinction risk.

They then applied the methodology widely-used to quantify carbon footprints – of which the Integrated Sustainability Analysis research group is a world leader – to link this extinction risk to global consumption patterns using the global supply chain database Eora.

An extinction-risk footprint was calculated by species, by economic sector, for 188 countries.

Co-author Associate Professor Arne Geschke previously co-wrote a Nature paper that demonstrated international trade is a key driver of biodiversity threats.

This new paper is a collaboration between the University of Sydney, IUCN, Newcastle University (UK) and the International Institute for Sustainability in Brazil. 

THE LANCET INFECTIOUS DISEASES: Threat of untreatable gonorrhoea could be tackled using an existing meningitis vaccine


Peer-Reviewed Publication

THE LANCET

Peer-reviewed / 2x Observational study / 1x Modelling study / People

  • Three research papers identify effective ways of improving protection against gonorrhoea infections in the face of rising cases and increasing drug resistance.
  • An observational study of the effectiveness of 4CMenB in a large-scale vaccination programme in South Australia indicates two doses of the vaccine is 33% effective against gonorrhoea in adolescents and young adults.
  • An observational study of health records for 16-23-year-olds in New York City and Philadelphia, USA, during 2016-2018 indicates receiving two doses of the meningitis vaccine 4CMenB provides 40% protection against gonorrhoea.  

Meningitis vaccines could help improve protection against gonorrhoea amid rising cases globally and increasing bacterial resistance to drugs used to treat the infection, according to findings from three linked papers published in The Lancet Infectious Diseases journal.

Gonorrhoea is a sexually transmitted infection (STI) which, if untreated, can lead to serious health conditions, including infertility in women, transmission to newborn babies, and increased risk of HIV. More than 80 million new cases of gonorrhoea were recorded worldwide in 2020. [1]

Declining effectiveness of drug treatments for the bacteria responsible – Neisseria gonorrhoeae – and the lack of a licensed vaccine to prevent the infection have raised concerns about the possibility that gonorrhoea may become more resistant to treatment, or even untreatable, in future.

Meningitis vaccines have been recommended by the WHO as part of its roadmap to reduce the global burden of meningitis. This includes offering meningitis vaccines as part of routine childhood immunisation strategies. [2] Since meningitis vaccines have become more widely available, studies have shown they also offer some protection against gonorrhoea, and that even partial protection could reduce cases of the infection considerably. However, questions have remained about the impacts and effectiveness of using meningitis vaccines against gonorrhoea.

In 2016, the WHO set a target to reduce gonorrhoea incidences by 90% by 2030, however an effective vaccine has yet to be developed. The three studies suggest that the 4CMenB vaccine may offer significant protection to young adults, and to men who have sex with men who might be at higher risk of infection.

Meningitis vaccine 4CMenB provides 40% protection against gonorrhoea

An observational study led by Dr Winston Abara, of U.S. Centers for Disease Control and Prevention, used health records to identify laboratory-confirmed cases of gonorrhoea and chlamydia – another leading STI – among 16–23-year-olds in New York City, NY and Philadelphia, PA, from 2016–2018. These cases were compared with immunisation records to determine people’s vaccination status with 4CMenB – which is licenced for use against meningitis – at the time of infection.

There were more than 167,000 infections (18,099 gonorrhoea, 124,876 chlamydia, and 24,731 co-infections) among almost 110,000 people. A total of 7,692 people had received the 4CMenB vaccine, with 4,032 (52%) receiving one dose, 3,596 (47%) two doses, and 64 (less than 1%) more than two doses. Full 4CMenB vaccination – receiving two doses – was estimated to provide 40% protection against gonorrhoea. One vaccine dose provided 26% protection.

Dr Winston Abara said: “Our findings suggest that meningitis vaccines that are even only moderately effective at protecting against gonorrhoea could have a major impact on prevention and control of the disease. Clinical trials focused on the use of 4CMenB against gonorrhoea are needed to better understand its protective effects and could also offer important insights towards the development of a vaccine specifically for gonorrhoea.” [3]

The authors acknowledge some limitations. The findings may not be generalisable to wider groups because the data used were from people aged 16–23 years in two large urban settings in the USA. Additionally, use of surveillance data means it is possible some participants’ infection and vaccination status were misclassified, affecting the analysis.

Two-dose course of 4CMenB is 33% effective against gonorrhoea in adolescents and young adults

South Australia’s ongoing 4CMenB vaccination programme is the most extensive globally, initially involving infants, children, adolescents, and young adults with a continuing state-funded program for infants and adolescents. In an observational study led by Professor Helen Marshall, of the Women’s and Children’s Hospital in Adelaide, researchers assessed the effectiveness of 4CMenB against meningitis and gonorrhoea as part of an infant, child and adolescent vaccination programme.

The authors analysed meningitis and gonorrhoea infection data held by the Communicable Disease Control Branch, and 4CMenB vaccination records from the Australian Immunisation Register. To estimate the effectiveness of 4CMenB against gonorrhoea, patients diagnosed with chlamydia acted as controls because of similar sexual behavioural risks reported in patients with either infection.
More than 53,000 adolescents and young adults received at least one dose of 4CMenB during the vaccination programme’s first two years. As well as being highly effective against meningococcal B meningitis and sepsis, in adolescents and young adults a two-dose course of 4CMenB was 33% effective against gonorrhoea

Professor Helen Marshall said: “While recent studies have provided evidence that 4CMenB vaccination is associated with reduced risk of gonorrhoea, the vaccine was only offered to adolescents and young adults for short periods. The unprecedented scale of South Australia’s 4CMenB vaccination programme offers valuable real-world evidence of the vaccine’s effectiveness against meningococcal B meningitis in children and adolescents, and gonorrhoea in adolescents and young people. This information is vital to inform global meningitis vaccination programmes and policy decisions.” [3]

The authors acknowledge some limitations. While a meaningful reduction in the rate of gonorrhoea among adolescents and young adults was not observed, this was likely due to small case numbers in this age group. The reported effectiveness of 4CMenB against gonorrhoea is consistent with other studies. Co-infections of gonorrhoea and chlamydia may play an important role in disease spread and severity, but factors associated with rates of co-infections are not well understood. However, the analysis shows 4CMenB effectiveness was similar whether co-infections were included or not.

Writing in a linked Comment on both observational studies, Professor Jason Ong, Dr Magnus Unemo, Annabelle Choong, Victor Zhao, and Dr Eric Chow, who were not involved in the studies, highlight key measures to adopt while efforts to develop a gonorrhoea vaccine continue: “In the meantime, we must continue to strengthen prevention efforts, improve access to early diagnosis and evidence-based treatment (index cases and sexual contacts), ensure quality-assured global surveillance systems to inform treatment guidelines, and invest in rapid, reliable point-of-care tests (for detection of N gonorrhoeae and its antimicrobial resistance) and the development of novel therapeutic antimicrobials.”

Vaccination based on infection risk could prevent 110,000 cases in England and save £8 million over 10 years

Until now, no study has assessed both the health impact and cost-effectiveness of using a vaccine to avert gonorrhoea infections.

A modelling study led by Professor Peter White, Imperial College London, UK, is the first analysis of the health and economic effects of using a vaccine to protect against gonorrhoea that accounts for its impact on future rates of infection.

A simulation model was developed to compare three realistic vaccination approaches among men-who-have-sex-with-men (MSM) in England: vaccination of all men attending sexual health clinics; vaccination following a confirmed gonorrhoea diagnosis; or vaccination based on risk of infection.

Based on their analysis and a balance of cases prevented vs the cost of vaccination, the authors recommend vaccinating MSM at highest risk of gonorrhoea infection with 4CMenB, which would prevent an estimated 110,000 cases and save £8 million over 10 years.

Professor Peter White said: “With a gonorrhoea-specific vaccine likely to take years to develop, a key question for policymakers is whether the meningitis vaccine 4CMenB should be used against gonorrhoea infection. Our analysis suggests that giving the vaccine to those at the greatest risk of infection is the most cost-effective way to avert large numbers of cases.” [3]

The authors explain that their estimation of the benefit of using 4CMenB to protect against gonorrhoea is conservative. Due to a lack of data at the time of the study, it was assumed a first vaccine dose offers no protection so only those who received a second dose were protected; however, the study by Abara and colleagues suggests one dose offers some protection, increasing the benefit of vaccination. Additionally, vaccination will reduce the future impacts of antimicrobial resistance (AMR) – which are likely to be substantial – meaning that vaccination would be even more beneficial than currently estimated, but further studies are needed to assess the potential future burden of AMR.

Writing in a linked Comment, Dr Mingwang Shen and Dr Lei Zhang, who were not involved in the study, highlight the significance of the findings reported by Professor Peter White and colleagues, saying: “The key message of the study is that vaccination using the 4CMenB vaccine according to the risk of the targeted MSM population is likely to be cost-effective, even if the vaccine were to have a relatively low efficacy and a short duration of protection. Such a strategy should be recommended and rolled out in a high-income country setting such as England.”

NOTES TO EDITORS

The study led by Professor Peter White was funded by the Medical Research Council and National Institute for Health Research. The study led by Professor Helen Marshall was funded by the Government of South Australia. The study led by Dr Winston Abara received no funding.

The study led by Professor Peter White was conducted by researchers from Imperial College London, University of Warwick, and Public Health England. The study led by Dr Winston Abara was conducted by researchers from U.S. Centers for Disease Control and Prevention, Philadelphia Department of Public Health, and New York City Department of Health and Mental Hygiene. The study led by Professor Helen Marshall was conducted by researchers from Women’s and Children’s Health Network, University of Adelaide, and SA Health, Australia.

[1] https://www.who.int/publications/i/item/9789240027077
[2] https://www.meningitis.org/meningitis-2030-plan-agreed-by-who
[3] Quote direct from author and cannot be found in the text of the Article.

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:

Paper 1: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00812-4/fulltext

Paper 2: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00754-4/fulltext

Paper 3: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00744-1/fulltext

For interviews with the Comment author, please contact: Prof. Jason Ong E) jason.ong@monash.edu T) +613 93416200

Few UK online sexually transmitted infection test services meet national standards


Peer-Reviewed Publication

BMJ

Few UK online sexually transmitted infection test services meet national recommended standards, with independent sector providers the least likely to be compliant, finds research published online in the journal Sexually Transmitted Infections.

The findings have concerning implications for patient care and public health, warn the researchers, who call for urgent regulatory change to ensure full compliance.

Online tests are either self-sampling, where the user orders a kit and takes a specimen themselves before posting it for laboratory analysis, or self-testing, where the user takes a specimen and interprets the test result themselves.

Online testing for sexually transmitted infections (STIs) is subject to limited regulatory oversight. But the British Association for Sexual Health and HIV (BASHH) and the Faculty of Sexual and Reproductive Healthcare (FSRH) have issued comprehensive national standards and guidelines covering all aspects of these services.

The researchers wanted to find out how well online UK STI test services comply with these standards and guidelines.

They searched Google and Amazon in June 2020 to find online providers, and found 31:13 offered self-test kits; 18 offered self-sample kits. They also found 2 laboratories servicing several providers.

All 13 self-test providers and 13 of the 18 self-sampling providers were privately run. All but one of the self-sample providers were from the UK.

The researchers analysed the information on the tests and associated services on each of the websites. And they requested further details from each provider in July 2020 and again in April 2021 on: intended users; the pretest process; the test process (test and specimen type); health information; monitoring and treatment after diagnosis; and accreditation.

This information was then compared with the BASHH and FSRH guidelines and standards.

Just 7 providers completed the questionnaire. These responses, together with the website information from all the providers, showed that few of them complied with the national guidelines and standards.

The commercial self-sample providers, who advertised to those with symptoms, didn’t differentiate by symptom severity. And 8 (7 private;1 NHS-commissioned) didn’t offer any advice on accessing preventive treatment after exposure to HIV, as recommended.

Self-test providers didn’t appear to provide any form of triage, and 5 offered tests that were intended for professional use only.

The range of eligible organisms for testing varied, although all self-sample providers offered tests for chlamydia and gonorrhoea. Two even claimed to test for organisms not included in routine NHS testing, even though these organisms aren’t considered STIs.

There was often no health promotion information given, and little in the way of sexual history taking. Inappropriate infections were tested for; incorrect specimen types were used; and there was little advice on what to do after a diagnosis.

Eleven self-test providers had at least one of their tests CE-marked—meaning that the product conforms to European health, safety, and environmental protection standards. Two claimed WHO approval and one claimed US Food and Drug Administration accreditation. 

One self-test provider marked their chlamydia and gonorrhoea tests with an NHS logo, describing themselves as an NHS provider, but it wasn’t clear if these products had been endorsed by the NHS. 

And while UK Accreditation Service (UKAS) accreditation was claimed for self-sample kits, there were no details of the specific laboratory service that had been accredited.

The researchers caution that the providers analysed may have updated their website information since the search was carried out and that those they assessed may not  represent the full range of online test service provision in the UK.

But they go on to say: “Very few online providers met the national STI management standards assessed, and there is concern that this will also be the case for service provision aspects that were not covered by this study.”

Online testing offers a convenient and flexible option for users, they point out. “However, the proliferation of providers that do not follow guidelines, in particular for-profit sites, jeopardises these advantages and puts users at risk. 

“If current trends continue, online testing usage will increase, resulting in more online providers as demand rises. Regulatory change is required to ensure that the standard of care received online meets national guidelines to protect patients and the wider population from the repercussions of underperforming or inappropriate tests.” 

They warn: “If we do not act now, patients will continue to receive suboptimal care with potentially significant adverse personal, clinical and public health implications.”

Notes for editors
Research: Assessment of online self-testing and self-sampling service providers for sexually transmitted infections against national standards in the UK in 2020 doi 10.1136/sextrans-2021-055318

Journal: Sexually Transmitted Infections

Funding: None declared
Link to AMS press release labelling system:
http://press.psprings.co.uk/AMSlabels.pdf

Embargoed link to research
http://press.psprings.co.uk/sti/april/sti055318.pdf
Public link once embargo lifts
https://sti.bmj.com/lookup/doi/10.1136/sextrans-2021-055318

Author contact
Dr Emma Harding-Esch, Clinical Research Department, London School of Hygiene & Tropical Medicine, London, UK
Tel: + 44 (0)7981 426 788
Email: Emma.Harding-Esch@lshtm.ac.uk

About the journal
Sexually Transmitted Infections is one of 70 specialist journals published by BMJ. The title is an official journal of the British Association of Sexual Health and HIV (BASHH) and the Australasian Chapter of Sexual Health Medicine (AChSHM).
http://sti.bmj.com

Embargoed 23.30 hours UK (BST) Tuesday 12 April 2022

Deforestation drives climate change that harms remaining forest

UCI researchers reconsider carbon storage with improved climate models, satellite data

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - IRVINE

Irvine, Calif., April 12, 2022 – In a paper published today in Nature Communicationsa team led by scientists from the University of California, Irvine, using climate models and satellite data, reveal for the first time how protecting tropical forests can yield climate benefits that enhance carbon storage in nearby areas.

Many climate scientists use computer simulations to mimic the planet’s climate as it exists today and how it may exist in the future as humanity keeps emitting greenhouse gases. Such models rely on accurate measurements all the moving parts of the climate system, from how much sunlight hits and warms the climate, to the response of forest biomass to changes in temperature, rainfall and atmospheric carbon dioxide levels. 

The list of moving parts is long, and one part that has until now remained unmeasured is the degree to which deforestation in tropical rainforests like the Amazon and the Congo contributes to additional forest losses because of its effect on regional climate.

“We used Earth system models to quantify what the climate impact from tropical deforestation is today,” said lead author Yue Li, UCI postdoctoral researcher in Earth system science. “Then, we used this information with satellite observations of forest biomass to figure out how nearby forests are responding to these changes.”

Jim Randerson, UCI professor of Earth system science, added: “This paper shows that avoiding deforestation yields carbon benefits in nearby regions as a consequence of climate feedbacks.”

He explained that for a new patch of deforestation in the Amazon, the regional climate changes that happen as a result led to an additional 5.1 percent more loss of total biomass in the entire Amazon basin. In the Congo, the additional biomass loss from the climate effects of deforestation is about 3.8 percent. Tropical forests store about 200 petagrams of carbon in their aboveground biomass. Since 2010, deforestation has been removing about 1 petagram of that carbon every year. (One petagram is equal to 1 trillion kilograms.)

Until now, climate modelers have, for lack of data, not considered tree mortality in their climate simulations. But by combining satellite data with climate variables, they obtained information about how sensitive carbon stored in vegetation is to climatic changes that result from tree mortality and fire.

“Deforestation has ramifications to forests growing elsewhere, because its consequences to the region's  air temperature and precipitation,” said co-author Paulo Brando, UCI professor of Earth system science. “Until recently, it was very difficult to isolate the effects of deforestation though.” 

By developing new estimates of regional carbon losses from deforestation-driven climate change in the Amazon and the Congo, the team provided information that will help scientists fine tune their models. This “might help us design better climate solutions,” Randerson said. By knowing exactly how much biomass is being lost through this activity, he explained, policymakers can make stronger arguments for why it’s worthwhile to curb deforestation, because they can now better describe the knock-on effects.

Joining Brando, Li and Randerson on this project, which was funded by the U.S. Department of Energy Office of Science and NASA, were Dave Lawrence at the National Center for Atmospheric Research and Hui Yang from the Max Planck Institute for Biogeochemistry in Germany.

About the University of California, Irvine: Founded in 1965, UCI is the youngest member of the prestigious Association of American Universities and is ranked among the nation’s top 10 public universities by U.S. News & World Report. The campus has produced five Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 36,000 students and offers 224 degree programs. It’s located in one of the world’s safest and most economically vibrant communities and is Orange County’s largest employer, contributing $7 billion annually to the local economy and $8 billion statewide. For more on UCI, visit www.uci.edu.

Media access: Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UCI faculty and experts, subject to availability and university approval. For more UCI news, visit news.uci.edu. Additional resources for journalists may be found at communications.uci.edu/for-journalists.

NOTE TO EDITORS: PHOTO AVAILABLE AT
https://news.uci.edu/2022/04/12/deforestation-drives-climate-change-that-harms-remaining-forest

Keeping apples fresh using clay films

Long-term food storage technology may help address potential food crises

Peer-Reviewed Publication

NATIONAL INSTITUTE FOR MATERIALS SCIENCE, JAPAN

Appearance changes 

IMAGE: EXTENT OF DECAY IN APPLES TREATED WITH CLAY FILM AND CLING WRAP view more 

CREDIT: MIHARU EGUCHI NATIONAL INSTITUTE FOR MATERIALS SCIENCE EGUCHI.MIHARU@NIMS.GO.JP

   An international research team consisting of NIMS, The University of Queensland and National Taiwan University has succeeded in creating a clay film with its gas permeability optimized for long-term storage of fresh produce by adjusting the sizes of the clay nanosheet particles comprising it. The team then uniformly coated the surfaces of various fruits with the film. This treatment kept the fruits’ respiration rates low without completely depriving them of oxygen, preventing them from decaying.

 

   Efforts have been made to develop gas barrier films using clay nanosheets. Although some researchers attempted to improve the film properties of clay nanosheets by adding organic polymers to them, films can also be formed using only clay nanosheets without additives. Only a few studies had previously evaluated the physical properties of clay films composed solely of clay nanosheets.

 

   This international joint research team focused on the gas permeability of clay films and found that a film composed of clay nanosheets with particle sizes in the range of several dozen nanometers (1 nm = one millionth of 1 mm) had relatively high permeability to gas molecules as they can pass through gaps between particles. This gas permeability is equivalent to that of plastic bags with minute pores used to store fresh produce. These bags are able to adequately reduce oxygen supply to fresh fruit, preventing it from ripening too rapidly. The gas permeability similarities between the clay film and the plastic bags inspired the research team to assess the ability of the clay film to preserve the quality of fresh produce for long periods of time.

In this research, the team applied a suspension of clay nanosheets to the surfaces of various fruits (e.g., apples, bananas and oranges) to form uniform films on their surfaces. The team also prepared untreated fruits and fruits covered in cling wrap for comparison. The gas emissions and appearance of these treated and untreated fruits were monitored for several months. As shown in the figure below, the untreated apples (the first photo from the left) had decayed by the end of the experimental period and the apples covered only in cling wrap (the fourth photo from the left) had also decayed and grown mold. By contrast, the apples coated with the clay film (the two middle photos) did not decay or grew mold, presumably because the film reduced the external oxygen supply needed for ripening and mold growth. In addition, the clay film was confirmed to be in tight contact with the surfaces of the apples it coated, suggesting that it may be able to effectively block the diffusion of ethylene into the air, a phytohormone which plays an important role in inducing fruit ripening.

 

   In addition to its potential ability to restrict the external oxygen supply and ethylene diffusion, the clay film may be able to prevent odor compounds produced by fresh produce from diffusing into the air, possibly making them less attractive to pests. In future research, the team plans to improve the ease of application and strength of the clay film to make it more suitable for preserving the quality of fresh produce during its transportation to the market.

 

   This project was carried out by an international joint research team consisting of Miharu Eguchi (Senior Researcher, Mesoscale Materials Chemistry Group, International Center for Materials Nanoarchitectonics, NIMS) and researchers from The University of Queensland and National Taiwan University. This work was supported in part by  JST-ERATO Yamauchi Materials Space-Tectonics Project.

 

***

 

   This research was published in Journal of Materials Chemistry A (the January 28, 2022 issue, pp. 1956-1964).

Surfing at the atomic scale: Scientists experimentally confirm new fundamental law for liquids

Surfing at the atomic scale: Scientists experimentally confirm new fundamental law for liquids
Dr Dehong Yu (left) and PhD candidate Caleb Stamper of the University of Wollongong at
 the time-of-flight neutron spectrometer Pelican. Not shown: Dr David Cortie. 
Credit: Australian Nuclear Science and Technology Organisation (ANSTO)

The first experimental evidence to validate a newly published universal law that provides insights into the complex energy states for liquids has been found using an advanced nuclear technique at ANSTO.

The work has just been published in the Journal of Physical Chemistry Letters as the editor's choice and featured on the front cover of the journal.

The equation for the vibrational density of states formulated by Alessio Zaccone and Matteo Bagglioli was published in a paper in PNAS in 2021, providing an answer to a question that has been elusive for at least a century.

The elegant mathematical theory has solved the problem of obtaining the distribution of these complex energy states for liquids.

"One of the most important quantities in the physics of matter is the distribution of the frequencies or vibrational energies of the waves that propagate in the material. It is particularly important as it is the starting point for calculating and understanding some fundamental properties of matter, such as specific heat and thermal conductivity, and the light-matter interaction, "said Prof Zaccone on the University of Milan website.

"The big problem with liquids is that, in addition to acoustic waves, there are other types of vibrational excitations related to low energies of the disordered motion of atoms and molecules— excitations that are almost absent in solids. These excitations are typically short-lived and are linked to the dynamic chaos of molecular motions but are nevertheless very numerous and important, especially at low energies. Mathematically, these excitations, known as 'instantaneous normal modes' or INMs in the specialized literature are very difficult to deal with as they correspond to energy states described by imaginary numbers."

The time-of-flight neutron spectrometer Pelican at ANSTO's Center for Neutron Scattering has been used to measure the vibrational densities of states for several liquid systems including water, , and polymer liquids. The Pelican instrument has the extreme sensitivity to measure rotational and translational vibrations over short time intervals and at low energies.

The experiments at ANSTO confirmed the linear relationship of the vibrational density of states with frequency at low energies as predicted by Alessio Zaccone and Matteo Bagglioli, as shown in the figure below.

Surfing at the atomic scale: Scientists experimentally confirm new fundamental law for liquids
Confirmation of the universal law with experimental VDOS measured by inelastic neutron
 scattering on real liquid systems including water, liquid metal, and polymer liquids. 
Credit: The Journal of Physical Chemistry Letters (2022). DOI: 10.1021/acs.jpclett.2c00297

With the COVID lockdown, no accessibility to instruments, the small team that included University of Wollongong Ph.D. candidate Caleb Stamper, Dr. Cortie and Dr. Yu decided to focus on re-analyzing past experimental data from a new perspective, to validate the new law, inspired by the theoretical work from Alessio Zaccone and Matteo Bagglioli.

"The exercise not only achieves such a great outcome but also provides a good introduction of neutron spectroscopy to Caleb, who has done an excellent job," said Dr. Yu as Caleb's ANSTO supervisor and the corresponding author of the paper.

The work would also help them address questions relating to phase transitions in superionic liquids in their work on thermoelectric materials.

"Major challenges arise because liquids are not mechanically stable, as the atoms in a liquid diffuse and the liquid as a whole will flow," explained Dr. Cortie.

The  is based on a , known as instantaneous normal modes, as described by Prof Zaccone above, which prescribe a set of instantaneous forces, frequencies, and velocities as quantities.


A complication in deriving a theory to predict the vibrational density of states in liquids arose because of the presence of a small fraction of "imaginary modes."

"Imaginary modes are important because they represent the fact that a liquid is not stable. The atoms in a liquid are strongly interacting with one another all the time but not in the same way a solid does. The relationship is not 'harmonic' meaning that the atoms are not going to be restored to the same configuration after an interaction. The atoms will continue to diffuse quickly and slide past each other," said Stamper.

"The imaginary modes reflect the negative curvature on the potential energy surface of a liquid. It is a very complex energy landscape but if you think of the analogy of a surfer on an ocean wave. The atoms in the liquid follow the curves of the wave itself (see the front cover of the journal). But the atoms can be in a position on the crest, under the surfboard or in the trough, always moving," said Dr. Yu.

"The law will play, for liquids, the same pivotal role that the Debye law plays for solids. It will serve as the foundation for the whole research field involving liquids and beyond.Molecular 'dances' determine how liquids take up heat

More information: Caleb Stamper et al, Experimental Confirmation of the Universal Law for the Vibrational Density of States of Liquids, The Journal of Physical Chemistry Letters (2022). DOI: 10.1021/acs.jpclett.2c00297

Alessio Zaccone et al, Universal law for the vibrational density of states of liquids, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2022303118

Journal information: Proceedings of the National Academy of Sciences , Journal of Physical Chemistry Letters 

Provided by Australian Nuclear Science and Technology Organisation (ANSTO)