Tech

Research team at Seoul National University (Prof. Tae-Woo Lee) and University of Pennsylvania (Prof. Andrew M. Rappe) developed perovskite light-emitting diodes (PeLEDs) with an external quantum efficiency (EQE) of 23.4%. The research results were published in Nature Photonics, which is the world-renowned international academic journal, on January 4th (Title: Comprehensive defect suppression in perovskite nanocrystals for high-efficiency light-emitting diodes).

Metal halide perovskites have very narrow spectral emission, excellent color purity, low material cost, and wide and easy color-tunability. Based on these advantages, perovskites are considered as a promising high color purity light emitter which can replace the conventional organic and inorganic quantum dot (QD) light emitters in displays and solid-state lighting technologies. Especially, perovskite is the only one emitter which can meet the standard of REC.2020. Therefore, perovskite is expected to contribute to the future ultra-high-definition television (UHD-TV) technology.

Since professor Tae-Woo Lee reported the PeLEDs with EQE of 8.53% which was comparable to that of phosphorescent organic light-emitting diode (LED) in Science in 2015, electroluminescence efficiencies of PeLEDs have been dramatically increased. After the Science paper, professor Tae-Woo Lee has lead the research fields of PeLEDs and recently achieved a EQE of 23.4% which was published in Nature Photonics. This EQE value is the highest efficiency in PeLEDs to date and even surpasses the highest EQE in InP-based green-emitting QD-LEDs (EQE = 13.6%). This improvement of EQE in PeLEDs is much faster than that in QD-LEDs which took 20 years to achieve EQE of 20% since it was first reported. These highlight the possibility of a commercialization of the perovskite emitters in industrial displays and solid-state lighting technologies.

Perovskites have severe problems to emit light at room temperature; small exciton binding energy induces direct dissociation of charge carriers and results in low luminescence efficiencies. To overcome this intrinsic problem, researchers have devoted to synthesizing colloidal perovskite nanocrystals which have a size of several nanometers (1 billionth of a meter). In such a small dimension, charge carriers can be spatially confined and can have high binding energy. However, due to the small size and concomitant high surface-to-volume ratio, perovskite nanocrystals have large surface defects. Furthermore, surface organic ligands are easily detached from the nanocrystal surfaces due to the dynamic binding nature, which induces many defects on the nanocrystal surfaces. Therefore, new strategy to effectively passivate the defects should be needed.

To solve these problems, Seoul National University research team led by Professor Tae-Woo Lee proposed a comprehensive strategy which introduces guanidinium organic cations into the conventional formamidinium-based perovskite nanocrystals. The introduced guanidinium cations controlled the defects both inside the nanocrystals and on the surfaces, and simultaneously confined the charge carriers more effectively inside the nanocrystals. As a result, perovskite nanocrystals achieve very high photoluminescence quantum efficiency (PLQE>90%) in both films and solutions. In addition, research team removed residual defects on nanocrystal surfaces by using a halide-based defect passivation agent, 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene (TBTB). With these comprehensive strategies, the research team demonstrated PeLEDs with the world's highest EQE (23.4%) and current efficiency (108 cd A-1). This is the highest device efficiency in PeLEDs to date and even surpasses the highest efficiency in InP-based green emitting QD-LEDs (EQE = 13.6%).

A collaborative research team at University of Pennsylvania, led by Professor Andrew M Rappe, investigated a detailed defect suppression mechanism through the density functional theory (DFT) calculation. The collaborative research team investigated the mechanism that guanidinium can be incorporated into the nanocrystals in small concentrations (~10%), above which guanidinium migrates to the surface outermost layer of nanocrystals. Furthermore, the collaborative research team studied how this guanidinium doping passivates the defects both inside the nanocrystals and on the surfaces. In addition, collaborative research team investigated the principle that halide-based TBTB material passivates the residual defects on the surfaces.

Prof. Tae-Woo Lee said, "We have proposed a comprehensive strategies to passivate the defects and increase the radiative recombination in the perovskite nanocrystals for demonstrating extremely efficient PeLEDs". "We expect that our work contributes to the commercialization of PeLEDs, as well as suggests a way to increase the luminescence efficiency of the PeLEDs." said Tae-Woo.

New research has found that growing up in a bilingual home can provide unexpected cognitive benefits later in life.

The study, published in the journal Scientific Reports, demonstrates for the first time that adults who acquired their second language as a young child (early bilinguals) are quicker at shifting attention and quicker at detecting visual changes compared to adults who learnt their second language later in life (late bilinguals).

Led by Dr Dean D'Souza of Anglia Ruskin University (ARU), the research saw 127 adults take part in two separate experiments. The first involved watching pictures on a screen, with one picture gradually changing and the other remaining the same. Early bilinguals noticed these changes much faster than late bilinguals.

The second experiment found that early bilinguals were better at controlling their attention. Specifically, they were quicker at disengaging attention from one picture in order to shift their focus to another.

Dr D'Souza and colleagues had previously found that infants raised in bilingual homes adapt to their more varied and unpredictable language environment by shifting their visual attention faster and more frequently. The findings of this new study suggest that these adaptations acquired as bilingual infants continue into adulthood.

Dr D'Souza, Senior Lecturer in Psychology at Anglia Ruskin University (ARU), said: "This study is an exciting extension of our previous research, which suggested that infants raised in bilingual homes adapt to their more complex language environments by switching attention faster and more frequently.

"This adaptation may help them to take advantage of multiple sources of visual information, such as mouth movements, facial expressions, and subtle gestures, ultimately helping them to learn multiple languages.

"The findings from our new research with bilingual adults suggest that some of these adaptations, including being quicker at shifting attention, are maintained into adulthood."

Young rugby league players could benefit from individualised nutrition plans to maximise performance and optimise recovery throughout their careers, according to QUT researchers.

The new study, published in the International Journal of Sport Nutrition and Exercise Metabolism, provides nutritional recommendations and considers potential supplements to improve players' physical capacity, health and recovery during the preparatory and competition phases of a season.

Lead researcher, Associate Professor Vince Kelly from QUT's Faculty of Health's Exercise and Nutrition Sciences, is a committee member of the National Rugby League Research Committee and has more than 20 years' experience in elite sport.

"Young players don't have the same access to dietary support as professional players do but it is just as important to invest in their nutritional needs," Associate Professor Kelly said.

"You don't put diesel into a Ferrari and high-performance players require the right type of fuel."

Key points:-

Professional rugby league is an intense physically-demanding sport, and young male players (aged 16-24) have incredibly high energy requirements.

Players' energy requirements are highly individual, and they may find it hard to meet current nutrition recommendations.

Research provides practical food and drink examples so that sports dietitians and coaches can help players eat and drink enough as part of a healthy diet.

Research shares information on evidence-based supplements via HASTA that could be used to maximise performance.

Associate Professor Kelly said healthy food habits for young players helps aid physical and mental wellbeing to cope with the demands of the game and as they mature.

A review and analysis of studies including players aged 16-24 highlighted the large variability in match and training profiles of rugby league players.

Co-author and PhD researcher Liam Oliver has prepared practical nutrition tables recommending take home packs for players to consume after a match.

The tables provide information for players to better manage their nutrition based on whether they are gaining or maintaining weight.

"For a collision sport like Rugby League, body mass and being heavier provides more momentum for tackling but this also leads to muscle damage so adequate protein may accelerate recovery," Assoc Prof Kelly said.

He said, for example, cherry concentrate taken consistently three days ahead of a match may improve muscle damage recovery while 30ml taken post-match may aid sleep, and blueberries or blackcurrants taken one-hour pre-match could improve sprint performance.

Currently, there are no nutritional recommendations across a complete season of rugby league and the researchers say future studies should apply to similar female-specific rugby league recommendations.

Nanofiltration (NF) is an advanced technology for treating wastewater containing organic micropollutants (OMPs).

Recently, a research group led by Prof. WAN Yinhua from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences developed a stable graphene oxide nanofiltration membrane with uniform pore size to remove OMPs.

The study was published in Chemical Engineering Journal on Jan. 20.

It proposes combining signal amplification strategy and defect chemistry to reduce membrane pore size distribution, thus offering a promising method for preparing highly selective NF membranes.

Graphene oxide (GO) shows great potential in molecular sieving for use in NF. GO membranes are generally prepared by stacking GO nanosheets on a porous support layer. However, the use of GO membranes is limited due to their low stability in aqueous environments.

In addition, large defects resulting from non-uniform deposition of GO nanosheets can cause membranes to have low retention capacity and can also cause serious membrane fouling.

In their study, the researchers proposed a targeted modification strategy to simultaneously enhance the antifouling capacity of GO membranes and regulate their nanochannels.

Ferric ions (Fe3+) are first added to the GO solution to prepare a stable GO membrane (GO-Fe). "The added Fe3+ can amplify the signal of the defects on the GO-Fe membrane where larger transverse defects form due to the repulsive interaction between the adjacent GO nanosheets," said Prof. LUO Jianquan from IPE.

The GO-Fe membrane surface is subsequently modified by a targeted coating layer consisting of tannic acid-aminopropyltriethoxysilane (TA-APTES), and the larger membrane defects with more Fe3+ are then patched by the thicker TA-APTES coating. Such a "speckled" TA-APTES coating can simultaneously improve the antifouling capacity and narrow the pore size distribution of the Fe3+-mediated GO membrane.

"Compared to the commercially available polyamide NF membranes, our GO membrane with targeted coating shows higher and more stable rejections on various OMPs, even in long-term operation, cross-flow filtration or under high pressure," said Prof. LUO.

A new collaborative study led by researchers at the National Institute for Environmental Studies, the University of Tokyo, and Michigan State University exposes the role of dams for mitigating flood risk under climate change.

Flood is amongst the costliest natural disasters. Globally, flood risk is projected to increase in the future, driven by climate change and population growth. The role of dams in flood mitigation, previously unaccounted for, was found to decrease by approximately 15% the number of people globally exposed to historical once-in-100-year floods, downstream of dams during the 21st century.

Currently, about half of major river systems worldwide are regulated by dams and more than 3,700 major dams are planned or under construction. Consequently, to realistically assess population exposure to present and future floods, current and future dam landscapes must be integrated into existing flood modeling frameworks.

Accounting for dams in river flood simulations, the number of people exposed to the historical once-in-100-year flood below dams were 7.2 and 13.4 million on average over 2006–2099 given a low and a medium-high greenhouse gas emission trajectory (RCP2.6 and RCP6.0, respectively). The populations exposed to flooding below dams decreased on average by 16.3% and 12.8% for the two trajectories compared to simulations not accounting for the flow regulations produced by dams. At the end of the 21st century, the decrease was further extended to 20.6% and 12.9% respectively.

To maintain the levels of flood protection that dams have provided, new dam operations will be required to offset the effect of climate change, possibly negatively affecting energy production and water storage. In addition, precise and reliable hydro-meteorological forecasts will be invaluable for enhancing flood protection and avoid excessive outflows. Given the many negative environmental and social impacts of dams, comprehensive assessments that consider both potential benefits and adverse effects are necessary for the sustainable development of water resources.

Loneliness in adults aged 50 and over during the COVID-19 lockdown was linked to worsening depressive and other mental health symptoms, according to a large-scale online study.

Loneliness emerged as a key factor linked to worsening symptoms of depression and anxiety in a study of more than 3,000 people aged 50 or over led by the University of Exeter and King's College London, and funded by The National Institute for Health Research (NIHR) Maudsley Biomedical Research Centre (BRC) .

Researchers had access to data going back to 2015 for participants of the PROTECT online study. They also found that a decrease in physical activity since the start of the pandemic was associated with worsening symptoms of depression and anxiety during the pandemic. Other factors included being female and being retired.

Dr Byron Creese, of the University of Exeter Medical School, who led the study, said: "Even before the pandemic, loneliness and physical activity levels were a huge issue in society, particularly among older people. Our study enabled us to compare mental health symptoms before and after COVID-19 in a large group of people aged 50 and over. We found that during lockdown, loneliness and decreased physical activity were associated with more symptoms of poor mental health, especially depression. It's now crucial that we build on this data to find new ways to mitigate risk of worsening mental health during the pandemic."

The study found that before the pandemic, lonely people would report an average of two symptoms of depression for at least several days over the previous last two weeks. During lockdown, lonely people reported either an increase in frequency of depressive symptoms, to more than half the days in the two week period, or a new symptom for at least several days in that timeframe. In people who were not lonely, levels of depressive symptoms were unaffected.

PROTECT began in 2011, and has 25,000 participants signed up. Designed to understand the factors involved in healthy ageing, the innovative study combines detailed lifestyle questionnaires with cognitive tests that assess aspects of brain function including memory, judgment and reasoning over time. In May, researchers included a new questionnaire designed to assess the impact of COVID-19 on health and wellbeing. Running from May 13 to June 8, the questionnaire was completed by 3,300 people, of which 1,900 were long-standing PROTECT participants. The study is continuing to run so that longer term outcomes can be assessed.

Zunera Khan, Research Portfolio Lead at Institute of Psychiatry, Psychology & Neuroscience said "We've found links between loneliness and a drop in physical exercise and worsening mental health symptoms. It should be within our power to find ways of keeping people socially engaged and active. Our online PROTECT platform ultimately aims to find new ways to engage people in their homes, however, technology can only be part of the picture. We need to ensure we can find new ways to help people stay active and social, whether they are online or not."

Professor Clive Ballard, Executive Dean and Pro-Vice Chancellor of the University of Exeter Medical School, who leads PROTECT, said: "We are only just beginning to learn the impact that COVID-19 is having on the health and wellbeing of older people. For example, the effect of any economic impact may not yet have emerged. Our largescale study will span a number of years, and will help us understand some of the longer-term effects of COVID-19 on mental health and wellbeing, and ultimately, on whether this has any knock-on effect on aspects of ageing, such as brain function and memory. "

The study plans to conduct further analysis on groups at particularly high risk, such as people with cognitive impairment and those with caring roles

The Ganges River - with the combined flows of the Brahmaputra and Meghna rivers - could be responsible for up to 3 billion microplastic particles entering the Bay of Bengal every day, according to new research.

The study represents the first investigation of microplastic abundance, characteristics and seasonal variation along the river and was conducted using samples collected by an international team of scientists as part of the National Geographic Society's Sea to Source: Ganges expedition.

Over two expeditions in 2019, 120 samples (60 each in pre- and post-monsoon conditions) were gathered at 10 sites by pumping river water through a mesh filter to capture any particles.

The samples were then analysed in laboratories at the University of Plymouth with microplastics found in 43 (71.6%) of the samples taken pre-monsoon, and 37 (61.6%) post-monsoon.

More than 90% of the microplastics found were fibres and, among them, rayon (54%) and acrylic (24%) - both of which are commonly used in clothing - were the most abundant.

Combining predicted microplastic concentration at the mouth of the river (Bhola, Bangladesh) with the discharge of the river, scientists estimate that between 1 billion and 3 billion microplastics might be being released from the Ganges Brahmaputra Meghna River Basin every day.

The research, published in Environmental Pollution, was led by researchers from the University of Plymouth's International Marine Litter Research Unit, working with colleagues from the Wildlife Institute of India, University of Dhaka, WildTeam, University of Exeter, National Geographic Society and the Zoological Society of London.

Research Fellow and National Geographic Explorer Dr Imogen Napper, the study's lead author, was among the participants in the Sea to Source: Ganges expedition. She said: "Globally, it has been estimated that 60 billion pieces of plastic are discharged into the ocean from rivers worldwide each day. However, what has been lacking until now has been a detailed analysis of how microplastic concentrations vary along a river's course. By working with local communities and partners, this expedition always aimed to help us stem the flow of plastic entering the Gangetic basin. These results provide the first step in understanding how it, as well as other major rivers, may contribute to oceanic microplastic."

The Ganges River rises in the Himalayas and runs through India and Bangladesh, where it joins the Brahmaputra and Meghna rivers shortly before reaching the Indian Ocean.

The combined flows of the three rivers are the largest in South Asia and form the most populous basin in the world, with over 655 million inhabitants relying on the water it provides.

The samples were collected during pre-monsoon (May to June 2019) and post-monsoon (October to December 2019), at sites ranging from Harsil closest to the source of the Ganges to Bhola in southern Bangladesh where it meets the Bay of Bengal.

The sample sites were selected to ensure a mixture of rural, urban, agricultural, tourism and religious locations, with the highest concentrations found closer to the river's mouth at Bhola, in Bangladesh.

Pre-monsoon samples collected there had four times as many particles as those taken at Harsil, while post-monsoon samples had double the amount.

Professor Richard Thompson OBE, Head of the International Marine Litter Research Unit at the University and one of the study's co-authors, said: "We know that rivers are a substantial source of microplastics in the ocean. But the information like this can help identify the key sources and pathways of microplastic and hence inform management interventions. With this type of evidence, we can progress toward using plastics more responsibly so as to get the many benefits they can bring without unnecessary contamination of the environment."

This study is the latest by the University in the field, with it being awarded a Queen's Anniversary Prize for Higher and Further Education in 2020 for its ground-breaking research and policy impact on microplastics pollution in the oceans.

It is currently among the partners in Preventing Plastic Pollution (PPP), a €14 million project which aims to prevent plastic pollution from rivers entering the English Channel, and LimnoPlast, a €4.1 million project examining the distribution of microplastics in European rivers and lakes.

By 2050, most people on Earth will live downstream of tens of thousands of large dams built in the 20th century, many of them already operating at or beyond their design life, according to a UN University analysis.

The report, "Ageing water infrastructure: An emerging global risk," by UNU's Canadian-based Institute for Water, Environment and Health, says most of the 58,700 large dams worldwide were constructed between 1930 and 1970 with a design life of 50 to 100 years, adding that at 50 years a large concrete dam "would most probably begin to express signs of aging."

Ageing signs include increasing cases of dam failures, progressively increasing costs of dam repair and maintenance, increasing reservoir sedimentation, and loss of a dam's functionality and effectiveness, "strongly interconnected" manifestations, the paper says.

The report says dams that are well designed, constructed and maintained can "easily" reach 100 years of service but predicts an increase in "decommissioning" -- a phenomenon gaining pace in the USA and Europe -- as economic and practical limitations prevent ageing dams from being upgraded or if their original use is now obsolete.

Worldwide, the huge volume of water stored behind large dams is estimated at 7,000 to 8,300 cubic kilometres -- enough to cover about 80% of Canada's landmass under a meter of water.

The report provides an overview of dam ageing by world region and primary function -- water supply, irrigation, flood control, hydropower, and recreation.

It also details the increasing risk of older dams, the rising maintenance expense, the declining functionality due to sedimentation, the benefits of restoring or redesigning natural environments, and the societal impacts -- pro and con -- that need to be weighed by policymakers deciding what to do. Notably, "the nature of these impacts varies significantly between low- and high-income countries."

The analysis also includes dam decommissioning or ageing case studies from the USA, France, Canada, India, Japan, and Zambia & Zimbabwe.

Climate change will accelerate the dam ageing process

"This report aims to attract global attention to the creeping issue of ageing water storage infrastructure and stimulate international efforts to deal with this emerging, rising water risk," says co-author Vladimir Smakhtin, Director of UNU-INWEH.

"Underlined is the fact that the rising frequency and severity of flooding and other extreme environmental events can overwhelm a dam's design limits and accelerate a dam's ageing process. Decisions about decommissioning, therefore, need to be taken in the context of a changing climate."

Notes lead author and UNU-INWEH Senior Researcher Duminda Perera: "This problem of ageing large dams today confronts a relatively small number of countries -- 93% of all the world's large dams are located in just 25 nations."

"Large dam construction surged in the mid-20th century and peaked in the 1960s - 70s," he says, "especially in Asia, Europe and North America, while in Africa the peak occurred in the 1980s. The number of newly-constructed large dams after that continuously and progressively declined."

According to the report, the world is unlikely to witness another large dam-building revolution as in the mid-20th century, but dams constructed then will inevitably be showing their age.

China has 23,841 large dams (40% of the world's total). And 32,716 large dams (55% of the world's total) are found in just four Asian countries: China, India, Japan, and the Republic of Korea -- a majority of which will reach the 50-year threshold relatively soon. The same is true of many large dams in Africa, South America, and Eastern Europe.

The pace of large dam construction has dropped dramatically in the last four decades and continues to decline in part because "the best locations for such dams globally have been progressively diminishing as nearly 50% of global river volume is already fragmented or regulated by dams," the report says.

As well, there are strong concerns regarding the environmental and social impacts of dams, and large dams in particular, as well as emerging ideas and practices on the alternative types of water storage, nature-based solutions, and types of energy production beyond hydropower.

Drivers of dam decommissioning

Public safety, escalating maintenance costs, reservoir sedimentation, and restoration of a natural river ecosystem are among the reasons driving dam decommissioning.

However, most dams removed to date have been small; decommissioning large dams (defined by ICOLD as 15 or more metres from lowest foundation to crest, or 5 to 15 metres impounding more than 3 million cubic metres) is "still in its infancy, with only a few known cases in the last decade."

"A few case studies of ageing and decommissioned large dams illustrate the complexity and length of the process that is often necessary to orchestrate the dam removal safely," adds co-author and UNU-INWEH Adjunct Professor R. Allen Curry, based at the University of New Brunswick.

"Even removing a small dam requires years (often decades) of continuous expert and public involvement, and lengthy regulatory reviews. With the mass ageing of dams well underway, it is important to develop a framework of protocols that will guide and accelerate the dam removal process."

Decommissioning will also have various positive and negative economic, social, and ecological impacts to be considered in a local and regional social, economic, and geographic context "critical to protect the broader, sustainable development objectives for a region," the report says.

"Overall, dam decommissioning should be seen as equally important as dam building in the overall planning process on water storage infrastructure developments."

"Ultimately, value judgments will determine the fate of many of these large water storage structures. It is not an easy process, and thus distilling lessons from and sharing dam decommissioning experiences should be a common global goal. Lack of such knowledge and lack of its reflection in relevant regional/national policies/practices may progressively and adversely affect the ability to manage water storage infrastructure properly as it is ageing."

Predictions of future climate change require a clear and nuanced understanding of Earth's past climate. In a study published today in Science Advances, University of Hawai'i (UH) at Mānoa oceanographers fully reconciled climate and carbon cycle trends of the past 50 million years--solving a controversy debated in the scientific literature for decades.

Throughout Earth's history, global climate and the global carbon cycle have undergone significant changes, some of which challenge the current understanding of carbon cycle dynamics.

Less carbon dioxide in the atmosphere cools Earth and decreases weathering of rocks and minerals on land over long time scales. Less weathering should lead to a shallower calcite compensation depth (CCD), which is the depth in the ocean where the rate of carbonate material raining down equals the rate of carbonate dissolution (also called "snow line"). The depth of the CCD can be traced over the geologic past by inspecting the calcium carbonate content of seafloor sediment cores.

Former oceanography graduate student Nemanja Komar and professor Richard Zeebe, both at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST), applied the most comprehensive computer model of the ocean carbonate chemistry and CCD to date, making this the first study that quantitatively ties all the important pieces of the carbon cycle together across the Cenozoic (past 66 million years).

Contrary to expectations, the deep-sea carbonate records indicate that as atmospheric carbon dioxide (CO2) decreased over the past 50 million years, the global CCD deepened (not shoaled), creating a carbon cycle conundrum.

"The variable position of the paleo-CCD over time carries a signal of the combined carbon cycle dynamics of the past," said Komar, lead author of the study. "Tracing the CCD evolution across the Cenozoic and identifying mechanisms responsible for its fluctuations are therefore important in deconvolving past changes in atmospheric CO2, weathering, and deep-sea carbonate burial. As CO2 and temperature dropped over the Cenozoic, the CCD should have shoaled but the records show that it actually deepened."

Komar and Zeebe's computer model allowed them to investigate possible mechanisms responsible for the observed long-term trends and provide a mechanism to reconcile all the observations.

"Surprisingly, we showed that the CCD response was decoupled from changes in silicate and carbonate weathering rates, challenging the long-standing uplift hypothesis, which attributes the CCD response to an increase in weathering rates due to the formation of the Himalayas and is contrary to our findings," said Komar.

Their research suggests that the disconnect developed partially because of the increasing proportion of carbonate buried in the open ocean relative to the continental shelf due to the drop in sea level as Earth cooled and continental ice sheets formed. In addition, ocean conditions caused the proliferation of open-ocean carbonate-producing organisms during that period of time.

"Our work provides new insight into the fundamental processes and feedbacks of the Earth system, which is critical for informing future predictions of changes in climate and carbon cycling," said Komar.

The researchers are currently working on new techniques to constrain the chronology of climate and carbon cycle changes over the past 66 million years.

The Singapore University of Technology and Design (SUTD) and its research collaborators have successfully demonstrated the four-dimensional (4D) printing of shape memory polymers in submicron dimensions which are comparable to the wavelength of visible light. This novel development has allowed researchers to now explore new applications in the field of nanophotonics.

4D printing enables 3D printed structures to change its configurations over time and is used in a wide variety of fields such as soft robotics, flexible electronics, and medical devices.

Different materials such as hydrogels, liquid crystal elastomers and magnetic nanoparticles embedded resists along with corresponding printing methods like Direct Ink Writing (DIW), Polyjet, Digital Light Processing (DLP) lithography and Stereolithography (SLA) have been developed for 4D printing. However, the material and patterning challenges inherent to these methods limit the resolution of 4D printing to ~10 μm at best.

To improve the resolution of 4D printing, the research team developed a shape memory polymer (SMP) photoresist suitable for two-photon polymerization lithography (TPL). Integrating this newly developed resist with TPL, they investigated submicron 4D printing of SMPs at which scale the printed structures can interact strongly with visible light. By programming with pressure and heat, the submicron structures can switch between colourless and colourful states (see image).

"It's remarkable that these 3D printed nanostructures are able to recover their shapes and structural colour after they've been mechanically flattened into a colourless, transparent state. This new resist that we've concocted allows for really fine structures to be printed while still retaining their properties as a shape memory polymer," said Associate Professor Joel K. W. Yang, principal investigator of the team from SUTD.

"By characterizing the photoresist, we printed the SMPs with ~300nm half pitch. The resolution is an order of magnitude higher than traditional high-resolution printing methods such as DLP and SLA. The dimensions of the structures can be conveniently controlled by varying the printing parameters such as laser power, write speed and nominal height," added Wang Zhang, first author and PhD student from SUTD.

It's mid-January 2021, and the first gray whales from the eastern North Pacific population have started to arrive in the breeding lagoons in Baja California, Mexico. Since the start of their southbound migration from their high latitude feeding grounds, several sightings of emaciated gray whales have already been reported along their migration route.

This has raised concern among scientists that the unusual mortality event (UME, an unexpected phenomenon during which a significant number of a marine mammal population dies), that started in January 2019, and which so far has resulted in 378 confirmed gray whale deaths, and possibly many more unrecorded, is entering its third year.

The gray whale - the longest migrating mammal

The gray whale (Eschrichtius robustus) is the only living species in the family Eschrichtiidae, in honour of the Danish zoologist Daniel Frederik Eschricht. Gray whales undertake annual migrations between feeding grounds in the Bering, Chukchi, and Arctic Seas, and breeding grounds from the Southern California Bight to lagoons along the Pacific coast of Baja California, Mexico.

During the summer feeding season, between May and October, the whales build up large amount of energy reserves, mainly in the form of blubber, to support the energetic costs of migration and while residing on the breeding grounds. Sufficient energy reserves is crucial for the reproduction and survival of gray whales, which do not feed during the migration and breeding season.

Mary Lou Jones and Steven Swartz, co-author on the current paper, conducted the first research and monitoring of the gray whales from 1977 to 1982 in Laguna San Ignacio (LSI) in Baja California Sur, Mexico. In 2006 with their colleague Dr Jorge Urban, co-author on the current paper, they initiated the Laguna San Ignacio Ecosystem Science Program (LSIESP), a project of the Ocean Foundation, which is a partnership with the Universidad Autónoma de Baja California Sur (UABCS) and international collaborators.

Drones - the bathroom scales of the whales

In 2017, Dr Fredrik Christiansen from the Aarhus Institute of Advanced Studies and the Dept. of Zoology at Aarhus University, and Professor Lars Bejder from the University of Hawai'i at Manoa, joined LSIESP to study the body condition of gray whales with the use of drone photogrammetry. The technique involves measuring the body length and width of gray whales from vertical photographs taken by drones above the whales, from which a measure of relative body condition (or fatness) of individual whales can be obtained.

Already in the second year of sampling, the researchers found a marked decline in the body condition of juvenile and adult gray whales visiting Laguna San Ignacio. The decline was also visible in 2019, at the start of the current UME. The decline in body condition also coincided with a drop in the number of mother-calf pairs sighted in Laguna San Ignacio, which indicated a reduction in the reproductive rate of female gray whales.

A similar UME occurred in 1999-2000, when 651 gray whales were recorded dead along the west coast of North America. During that two-year event, the gray whale population declined with about 25% from about 21,000 animals in 1998 to about 16,000 in 2002. It is yet unknown what effects the current UME is having on the eastern North Pacific population.

Starvation, decline in prey availability and warming of the Arctic

While the study by Dr Fredrik Christiansen and colleagues suggests that the decline in survival and reproductive rates of gray whale during the current UME was caused by starvation, the underlying factors that caused this reduction in body condition has not yet been determined. The fact that gray whales in 2018 and 2019 arrived on their Mexican breeding grounds already in significantly poorer body condition, indicates that this decline must have occurred either during the previous feeding season and/or during the southbound migration.

"It appears that a large number of gray whales are leaving their feeding grounds already in a poor nutritional state and by the time they have completed the breeding season in Mexico they have depleted their energy reserves and starve to death", says Dr Fredrik Christiansen.

A decline in prey availability on the main feeding grounds is hence the most probably explanation for the current UME. Since the late 1980s, there has been a decline in the abundance and biomass of amphipods, the main prey for gray whales, in the central Chirikov Basin, the main feeding area for gray whales in the Bering Sea. This in turn is believed to be caused by warming of Arctic waters as a result of natural and/or human-induced climate change. If that is the case, UMEs like this one might become more frequent, which could result in a decline in gray whale numbers in coming decades.

As the world keeps struggling with the Covid-19 pandemic, LSIESP researchers are preparing for the 2021 field season in Laguna San Ignacio to hopefully get one step closer to understanding the full extent of the current gray whale UME.

Metagenomics - the study of genetic material from an environmental sample - is growing as species evolve or are discovered across the globe. To correlate the newly developed microbiomes with existing data sets, a team of researchers based in China has developed the Microbiome Search Engine 2 (MSE 2). It was published on Jan. 19 in mSystems, a journal of the American Society for Microbiology.

"Here, we introduce MSE 2, a microbiome database platform for searching query microbiomes in the global metagenome data space based on taxonomic or functional similarity of the whole microbiome," said co-first author JING Gongchao, Single-Cell Center, CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology (QIBEBT), Chinese Academy of Sciences (CAS).

The previous version of the search engine limited queries to taxonomical similarities, meaning the functional genes had to match. There was not a way for researchers to compare different samples that performed the same function in various microbiomes. The ability to study how the same function may have evolved in different microbes could offer guidance in identifying and treating diseases, according to JING.

"A search-based strategy is useful for large-scale mining of microbiome datasets, providing a bird's eye view of the microbiome data space and disease diagnosis via microbiome big data," JING said.

"The new ability to search the microbiome space via functional similarity greatly expands the scope of search-based mining of the microbiome big data," JING added. "By adding a function-based dimension for these and related applications, MSE 2 should accelerate large-scale mining of the ever-expanding metagenome data space."

MSE 2 includes an extended database with meta data from 819 studies, updated data compatibility to better incorporate newly available data sets and a user-friendly interface. A single query takes less than half of a second to search against the entire database of more than 260,000 samples.

"Over the past decade we have been passionately collecting published microbiome data - they record the kinds of microbe species and the types of microbial communities that have ever lived on our planet. By collecting and curating them in a minable database, MSE 2 allows these invisible but pivotal creatures on Earth to be "remembered" by future generations, and those scientists who first discovered them to be recognized", said co-first author LIU Lu, also from Single-Cell Center.

The tracking of eye movement is one of the key elements of virtual and amplified reality technologies (VR/AR). A team from MSU together with a professor from RUDN University developed a mathematical model that helps accurately predict the next gaze fixation point and reduces the inaccuracy caused by blinking. The model would make VR/AR systems more realistic and sensitive to user actions. The results of the study were published in the SID Symposium Digest of Technical Papers.

Foveated rendering is a basic technology of VR systems. When a person looks at something, their gaze is focused on the so-called foveated region, and everything else is covered by peripheral vision. Therefore, a computer has to render the images in the foveated region with the highest degree of detail, while other parts require less computational powers. This approach helps improve computational performance and eliminates issues caused by the gap between the limited capabilities of graphic processors and increasing display resolution. However, foveated rendering technology is limited in speed and accuracy of the next gaze fixation point prediction because the movement of a human eye is a complex and largely random process. To solve this issue, a team of researchers from MSU together with a professor from RUDN University developed a mathematical modeling method that helps calculate next gaze fixation points in advance.

"One of the issues with foveated rendering is timely prediction of the next gaze fixation point because vision is a complex stochastic process. We suggested a mathematical model that predicts gaze fixation point changes," said Prof. Viktor Belyaev, a Ph.D. in Technical Sciences from the Department of Mechanics and Mechatronics of RUDN University.

The predictions of the model are based on the study of the so-called saccadic movements (fast and rhythmic movements of the eye). They accompany the shifts of our gaze from one object to another and can suggest the next fixation point. The ratio between the length, range, and maximum speed of saccadic eye movements is determined by certain empirical regularities. However, these models cannot be used by eye trackers to predict eye movements because they are not accurate enough. Therefore, the researchers focused on a mathematical model that helped them obtain saccadic movement parameters. After that, this data was used to calculate the foveated region of an image.

The new method was tested experimentally using a VR helmet and AR glasses. The eye tracker based on the mathematical model was able to detect minor eye movements (3.4 minutes, which is equal to 0.05 degrees), and the inaccuracy amounted to 6.7 minutes (0.11 degrees). Moreover, the team managed to eliminate the calculation error caused by blinking: a filter included in the model reduced the inaccuracy 10 times. The results of the work could be used in VR modeling, video games, and in medicine for surgeries and vision disorders diagnostics.

"We have effectively solved the issue with the foveated rendering technology that existed in the mass production of VR systems. In the future, we plan to calibrate our eye tracker to reduce the impact of display or helmet movements against a user's head," added Prof. Viktor Belyaev from RUDN University.

Good news for the green transition: Flowery diets help predatory insects help farmers keep pests in check
Predatory insects have been shown to live longer when they have access to nectar and pollen, according to a new study by researchers at the University of Copenhagen. Thus, flowers don't just benefit insects, they help farmers farm sustainably. Predatory insects are skilled pest controllers whose hunting reduces the need for agricultural pesticides.

Until now, it was believed that predatory insects needed prey to survive. But in a systematic review conducted at the University of Copenhagen's Department of Plant and Environmental Sciences, researchers collected, compared and analyzed data from studies around the world to conclude that most predators benefit greatly from flowers, and can even survive for extended periods of time on nectar and pollen alone. Thus, farmers can promote a consistent production of natural enemies to defeat pests by incorporating flowering strips and flowering margins in their fields:

"By planting flowering margins and strips alongside fields, one can ensure an ever-abundant supply of predatory insects such as hoverflies, lacewings, minute pirate bugs, phytoseiid mites and two-spot ladybugs. Pollen and nectar are supplements that beneficial insects can survive on when pests aren't around. And, the plants in margins and strips provide many other types of insects for to prey on as well. By planting a wide variety of flowers that bloom both early and late in the season, one can ensure for an optimal effect that ensures the survival of predators throughout the growing season," says Associate Professor Lene Sigsgaard of the Department of Plant and Environmental Sciences. She adds:

"This is good news for the green transition, as effective pest control can help reduce the use of agricultural pesticides. On top of the that, the presence of more flowers imroves pollination and biodiversity, as they attract more insects and pollinators into fields."

The researchers underscore that in order for predatory insects to access flower nectar, easily accessible open flowers need to be planted, as predatory insects aren't equipped with the long feeding tubes that bees have. Examples of open and beneficial flowers are wild carrot, ox eye daisy, dill and dandelion.

Up to 8 times longer lives on the best flowers

Food from flowers boosts energy for predators. Specifically, the researchers found that across all predatory insects, females survive 2.2 times longer with access to flowers, and males 1.7 times longer, compared to insects that only have access to water, but no flowers.

Still, not all predatory insects and flowers are the same. Some predators manage to lay eggs with access to flowers alone. Of the 17 predatory insect species tested with more than one species of flowers, nine--including lacewings, two-spot ladybugs and minute pirate bugs--lived significantly longer with flowers. The lifespans of the remaining 8 species, including a predatory mite, were not significantly longer.

There are differences among flowers as well. With buckwheat, which has open flowers and is a cultivated crop, predator insects lived an average of 8.6 times longer than on water alone. Mallow, yarrow and ox eye daisy are also highly valuable flowers for predatory insects, while lotus and viper's bugloss, due to their deeper tubes, are less helpful.

'It's quite an elixir of life. Wisely planted flowers can contribute to robust crop production because predatory insects will live longer and better," says Lene Sigsgaard, who continues:

"It pays to design tomorrow's agriculture so as to accommodate wild flowering plants alongside fields. For the greatest impact, this needs to be done on an informed basis, which is why we are looking at how to design mixed flowering strips and flowering margins that benefit both predatory insects and pollinators. This will reduce the need for other forms of pest control while supporting biodiversity," says Lene Sigsgaard.

Use perennials and multiple species

The researchers recommend native, perennial flowers to create permanent habitats for predatory insects, places where they can winter as well. It is also important to have a wide variety of species that bloom during different seasons and benefit different insects. The researchers work with 30-40 different native species in the field, including grasses, which help make flower strips more robust.

The researchers are continuing to generate more knowledge about which flowers and flower combinations are particularly beneficial for insect life in general, and more specifically, for beneficial insects and their contribution to biological pest control and pollination.

The research results are published in the recognized journal Biological Control.

Popular in aquariums all over the world, the zebrafish is native to South Asia. But here in a Cincinnati Children's Hospital Medical Center's laboratory, the freshwater variant plays a vital role in scientific discovery.

The iconic stripes are eye-catching but it's the transparency of zebrafish embryonic tissue which are most prized by researchers like Oriana Zinani, a fifth-year doctoral student in molecular developmental biology in the University of Cincinnati College of Medicine. The patterning of the zebrafish's spine gives the appearance of stripes; it is controlled by segmentation genes which function like a clock.

Zinani is part of a team of scientists in the laboratory of Ertuğrul M. Özbudak, PhD, associate professor of pediatrics at UC and Cincinnati Children's Hospital Medical Center. The team is studying a gene mutation that causes congenital scoliosis, a birth defect characterized by failure of separation of vertebrae and disordered rib cages. Zebrafish eggs are fertilized and develop outside of the mother's body making visualization with high resolution imaging easier for researchers. Zebrafish and humans share 70% of the same genes.

"We can see exactly what's happening while it's happening in zebrafish providing us with insight for human embryonic development," says Zinani. "My research asks the question, 'How does the zebrafish embryo robustly achieve precise development in a variety of environments that consider variables such as temperature fluctuations and exposure to different oxygenation levels?' We realized that embryos need to develop mechanisms to filter out the noise for development, and I focus on what those mechanisms involve."

Scientists for some time have known that specific genes pair up on the same chromosome and appear together or "co-express" in cells and tissues. In humans, at least 10% of genes pair on the same chromosome. Why this occurs has been unknown but the team -- including Zinani, Özbudak, Kemal Keseroğlu, a research fellow at Cincinnati Children's, and Ahmet Ay of Colgate University -- did an experiment separating two genes that were paired together to determine the role they may play in spinal column development.

The team's findings were recently published in the scholarly journal Nature.

Using the gene-editing tool CRISPR-Cas9, the research team performed a simple experiment using a zebrafish model and separated two genes that pair up to control the healthy development of the spine. The separated genes have broken their co-expression. Instead of the precise segment boundaries we are used to seeing in zebrafish embryos, we see instead a fused tissue, which ultimately leads to failed vertebrae formation.

"With two paired functional genes we see normal healthy development," says Zinani. "If this were a human the person would have no disease. If we take the normal gene pairs and separate them, without creating any mutation at all, we see disease development under environmental stress."

Images of a zebrafish with the separated genes show a jagged vertebrae that's cracked, broken and fused, explains Zinani. The zebrafish has a diseased phenotype leading to congenital scoliosis. Researchers also raised the zebrafish with separated gene pairs in different temperatures to better understand the impact of environmental pressure on development. Paired genes lead to beneficial spinal development, particularly under environmental stress. Separation of the genes are more likely to lead to deformities of the spine and congenital scoliosis in zebrafish.

"What is also exciting is many genes responsible for the development of diabetes, cancer and autoimmune disorders also present in gene pairs in human genome" says Zinani. "We believe more research will show the importance of those genes maintaining close proximity to their partners. If the process of having genes next to each other influences healthy development and adult life, we have a new target to consider in studying disease formation."

Özbudak said Zinani's work will be useful in future research.

"What Oriana discovered during her graduate study could shed light on why organisms maintain particular gene orders in their genome: to coordinate expression of genes functioning in same biological processes," he said.