This hydrogen fuel machine could be the ultimate guide to self-improveme

Study co-led by Berkeley Lab uncovers secret behind humble material's surprise performance as an artificial photosynthesis device

DOE/LAWRENCE BERKELEY NATIONAL LABORATORY

Research News

 

IMAGE: GUOSONG ZENG, A POSTDOCTORAL SCHOLAR IN BERKELEY LAB'S CHEMICAL SCIENCES DIVISION, AT WORK TESTING AN ARTIFICIAL PHOTOSYNTHESIS DEVICE MADE OF GALLIUM NITRIDE. ZENG, ALONG WITH BERKELEY LAB STAFF SCIENTIST FRANCESCA... view more 

CREDIT: THOR SWIFT/BERKELEY LABree years ago, scientists at the University of Michigan discovered an artificial photosynthesis device made of silicon and gallium nitride (Si/GaN) that harnesses sunlight into carbon-free hydrogen for fuel cells with twice the efficiency and stability of some previous technologies.

Now, scientists at the Department of Energy's (DOE's) Lawrence Berkeley National Laboratory (Berkeley Lab) - in collaboration with the University of Michigan and Lawrence Livermore National Laboratory (LLNL) - have uncovered a surprising, self-improving property in Si/GaN that contributes to the material's highly efficient and stable performance in converting light and water into carbon-free hydrogen. Their findings, reported in the journal Nature Materials, could help radically accelerate the commercialization of artificial photosynthesis technologies and hydrogen fuel cells.

"Our discovery is a real game-changer," said senior author Francesca Toma, a staff scientist in the Chemical Sciences Division at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). Usually, materials in solar fuels systems degrade, become less stable and thus produce hydrogen less efficiently, she said. "But we discovered an unusual property in Si/GaN that somehow enables it to become more efficient and stable. I've never seen such stability."

Previous artificial photosynthesis materials are either excellent light absorbers that lack durability; or they're durable materials that lack light-absorption efficiency.

But silicon and gallium nitride are abundant and cheap materials that are widely used as semiconductors in everyday electronics such as LEDs (light-emitting diodes) and solar cells, said co-author Zetian Mi, a professor of electrical and computer engineering at the University of Michigan who invented Si/GaN artificial photosynthesis devices a decade ago.

When Mi's Si/GaN device achieved a record-breaking 3 percent solar-to-hydrogen efficiency, he wondered how such ordinary materials could perform so extraordinarily well in an exotic artificial photosynthesis device - so he turned to Toma for help.

HydroGEN: Taking a Team Science approach to solar fuels

Mi had learned of Toma's expertise in advanced microscopy techniques for probing the nanoscale (billionths of a meter) properties of artificial photosynthesis materials through HydroGEN, a five-national lab consortium supported by the DOE's Hydrogen and Fuel Cell Technologies Office, and led by the National Renewable Energy Laboratory to facilitate collaborations between National Labs, academia, and industry for the development of advanced water-splitting materials. "These interactions of supporting industry and academia on advanced water-splitting materials with the capabilities of the National Labs are precisely why HydroGEN was formed - so that we can move the needle on clean hydrogen production technology," said Adam Weber, Berkeley Lab's Hydrogen and Fuel Cell Technologies Lab Program Manager and Co-Deputy Director of HydroGEN.

Toma and lead author Guosong Zeng, a postdoctoral scholar in Berkeley Lab's Chemical Sciences Division, suspected that GaN might be playing a role in the device's unusual potential for hydrogen production efficiency and stability.

To find out, Zeng carried out a photoconductive atomic force microscopy experiment at Toma's lab to test how GaN photocathodes could efficiently convert absorbed photons into electrons, and then recruit those free electrons to split water into hydrogen, before the material started to degrade and become less stable and efficient.

They expected to see a steep decline in the material's photon absorption efficiency and stability after just a few hours. To their astonishment, they observed a 2-3 orders of magnitude improvement in the material's photocurrent coming from tiny facets along the "sidewall" of the GaN grain, Zeng said. Even more perplexing was that the material had increased its efficiency over time, even though the overall surface of the material didn't change that much, Zeng said. "In other words, instead of getting worse, the material got better," he said.

To gather more clues, the researchers recruited scanning transmission electron microscopy (STEM) at the National Center for Electron Microscopy in Berkeley Lab's Molecular Foundry, and angle-dependent X-ray photon spectroscopy (XPS).

Those experiments revealed that a 1 nanometer layer mixed with gallium, nitrogen, and oxygen - or gallium oxynitride - had formed along some of the sidewalls. A chemical reaction had taken place, adding "active catalytic sites for hydrogen production reactions," Toma said.

Density functional theory (DFT) simulations carried out by co-authors Tadashi Ogitsu and Tuan Anh Pham at LLNL confirmed their observations. "By calculating the change of distribution of chemical species at specific parts of the material's surface, we successfully found a surface structure that correlates with the development of gallium oxynitride as a hydrogen evolution reaction site," Ogitsu said. "We hope that our findings and approach - a tightly integrated theory-experiments collaboration enabled by the HydroGEN consortium - will be used to further improve the renewable hydrogen production technologies."

Mi added: "We've been working on this material for over 10 years - we know it's stable and efficient. But this collaboration helped to identify the fundamental mechanisms behind why it gets more robust and efficient instead of degrading. The findings from this work will help us build more efficient artificial photosynthesis devices at a lower cost."

Looking ahead, Toma said that she and her team would like to test the Si/GaN photocathode in a water-splitting photoelectrochemical cell, and that Zeng will experiment with similar materials to get a better understanding of how nitrides contribute to stability in artificial photosynthesis devices - which is something they never thought would be possible.

"It was totally surprising," said Zeng. "It didn't make sense - but Pham's DFT calculations gave us the explanation we needed to validate our observations. Our findings will help us design even better artificial photosynthesis devices."

"This was an unprecedented network of collaboration between National Labs and a research university," said Toma. "The HydroGEN consortium brought us together - our work demonstrates how the National Labs' Team Science approach can help solve big problems that affect the entire world."

CAPTION

Guosong Zeng, a postdoctoral scholar, and Francesca Toma, a staff scientist, both in Berkeley Lab's Chemical Sciences Division, test an artificial photosynthesis device made of gallium nitride. Rather than degrading over time, which is typical for devices that turn water and light into hydrogen fuel, Toma and Zeng discovered that this device improves.

CREDIT

Thor Swift/Berkeley Lab 

Co-authors on the paper include Guiji Liu, Jason Cooper, and Chengyu Song at Berkeley Lab; and Srinivas Vanka at the University of Michigan.

The Molecular Foundry is a DOE Office of Science user facility at Berkeley Lab.

This work was supported by the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under DOE's Office of Energy Efficiency and Renewable Energy.

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 14 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab's facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy's Office of Science.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news rel

Incidence of 30-Day Venous Thromboembolism in Adults Tested for SARS-CoV-2 Infection in an Integrated Health Care System in Northern California

Nareg H. Roubinian, MD^1,2,3; Jennifer R. Dusendang, MPH¹; Dustin G. Mark, MD^1,2; et alDavid R. Vinson, MD^1,2; Vincent X. Liu, MD^1,2; Julie A. Schmittdiel, PhD¹; Ashok P. Pai, MD²

Author Affiliations Article Information

JAMA Intern Med. Published online April 5, 2021. doi:10.1001/jamainternmed.2021.0488

COVID-19 Resource Center

Hospitalization for COVID-19 is associated with high rates of venous thromboembolism (VTE).¹ Whether SARS-CoV-2 infection affects the risk of VTE outside of the hospital setting remains poorly understood. We report on the 30-day incidence of outpatient and hospital-associated VTE following SARS-CoV-2 testing among adult members of the Kaiser Permanente Northern California health plan.

Methods

We performed a retrospective cohort study of 220 588 adult members of the Kaiser Permanente Northern California health plan who were tested for SARS-CoV-2 by polymerase chain reaction from February 25 through August 31, 2020. For participants with multiple SARS-CoV-2 tests, the index date was the first test date with a positive result or the first test date with a negative result if all tests were negative. We characterized study participants by demographic information, comorbidities, testing location, and level of care, excluding participants who were asymptomatic at the time of testing or had received anticoagulation in the prior year. We assessed incidence and timing of 30-day VTE using diagnosis codes, new anticoagulant prescriptions, and VTE encounters with a centralized anticoagulation management service.² We identified inpatient anticoagulation based on consecutive-day administration of VTE treatment dosing of oral, intravenous, or subcutaneous anticoagulants. We defined VTE as outpatient events when diagnosed in outpatient or emergency department settings and as hospital-associated events when diagnosed during or after hospitalization. The Kaiser Permanente Northern California institutional review board approved the study and waived informed consent according to the Common Rule. Analyses were performed using SAS, version 9.4 (SAS Institute Inc); 2-sided χ² and Kruskal-Wallis tests with P < .05 were considered to be statistically significant.

Results

Of the 220 588 patients with symptoms who were tested for SARS-CoV-2 (mean [SD] age, 47.1 [17.3] years; 131 075 [59.4%] women), 26 104 (11.8%) had a positive result (Table 1). Within 30 days of testing, a VTE was diagnosed in 198 (0.8%) of the patients with a positive SARS-CoV-2 result and 1008 (0.5%) of patients with a negative result (P < .001). Viral testing took place in an outpatient setting for most of the patients (117 of 198; 59.1%) who had a positive SARS-CoV-2 test result and later developed VTE. Of these 117 patients, 89 (76.1%) required subsequent hospitalization. Among those patients who underwent outpatient viral testing, 30-day VTE incidence was higher among those with a positive SARS-CoV-2 result than among those with a negative result (4.7 vs 1.6 cases per 1000 individuals tested; P < .001). Compared with patients with a negative SARS-CoV-2 test result, those with a positive result had a higher 30-day incidence of hospital-associated (5.8 vs 3.0 cases per 1000 individuals tested; P < .001) but not outpatient VTE (1.8 vs 2.2 cases per 1000 tested; P = .16; Table 2). Posthospital VTE occurred with similar frequency among participants with positive and negative SARS-CoV-2 test results (1.0 vs 1.1 cases per 1000 tested; P = .51). In patients with a positive result, the median (interquartile range) number of days (11 [4-21] vs 11 [1-25]; P = .67) from viral testing to anticoagulation was comparable for outpatient and posthospital VTE.

Discussion

The incidence of outpatient VTE among symptomatic patients with positive SARS-CoV-2 test results was similar to that of patients with negative results. In parallel to recent reports, posthospital VTE incidence did not differ by SARS-CoV-2 status and was comparable with that seen in clinical trials of thromboprophylaxis.^3,4 A VTE is a potentially preventable complication of SARS-CoV-2 infection, especially in outpatients with risk factors for thrombosis or severe COVID-19. Ongoing randomized clinical trials will determine whether the risks and benefits of prophylactic anticoagulation in outpatients with COVID-19 will improve clinical outcomes.⁵ Recognizing that the timing of outpatient VTE paralleled that of posthospital events, the 30-day duration of outpatient thromboprophylaxis proposed in clinical trials may be sufficient to mitigate virally mediated thromboinflammation.⁶

Limitations of VTE diagnosis include changes in diagnostic testing patterns because of possible infection transmission or recognition of VTE risk with SARS-CoV-2, as well as increased use of empirical anticoagulation and/or anti-inflammatory agents. Our approach to case identification may have missed VTE; however, incidence in hospitalized patients paralleled that identified using natural language processing methods.¹ Lastly, outpatient VTE burden may have been underestimated if diagnostic imaging occurred shortly after hospitalization.

These findings suggest that VTE incidence outside of the hospital is not significantly increased with SARS-CoV-2 infection and argue against the routine use of outpatient thromboprophylaxis outside of clinical trials. Recognizing that COVID-19–associated symptoms and disability may persist for months, clinical trials and additional longitudinal studies are needed to understand the role of outpatient and hospital treatment in 90-day VTE.

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Article Information

Accepted for Publication: February 1, 2021.

Published Online: April 5, 2021. doi:10.1001/jamainternmed.2021.0488

Corresponding Author: Nareg H. Roubinian, MD, Division of Research, Kaiser Permanente Northern California, 2000 Broadway, Oakland, CA 94612 (nareg.n.roubinian@kp.org).

Author Contributions: Dr Roubinian and Ms Dusendang had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: All authors.

Acquisition, analysis, or interpretation of data: Roubinian, Dusendang, Mark, Vinson, Schmittdiel, Pai.

Drafting of the manuscript: Roubinian, Dusendang, Liu.

Critical revision of the manuscript for important intellectual content: Roubinian, Dusendang, Mark, Vinson, Schmittdiel, Pai.

Statistical analysis: Roubinian, Dusendang, Schmittdiel.

Obtained funding: Roubinian.

Administrative, technical, or material support: Liu, Schmittdiel, Pai.

Supervision: Roubinian, Schmittdiel.

Conflict of Interest Disclosures: Dr Roubinian reported grants from the National Institutes of Health and the National Heart, Lung, and Blood Institute (R01HL126130) during the conduct of the study. Dr Liu reported grants from the National Institute of General Medical Sciences (R35GM128672) during the conduct of the study. No other disclosures were reported.

Funding/Support: Funding for this work was provided by The Permanente Medical Group Delivery Science and Applied Research Program.

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

References

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Bilaloglu  S, Aphinyanaphongs  Y, Jones  S, Iturrate  E, Hochman  J, Berger  JS.  Thrombosis in hospitalized patients with COVID-19 in a New York City health system.   JAMA. 2020;324(8):799-801. doi:10.1001/jama.2020.13372
ArticlePubMedGoogle ScholarCrossref

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Packard  A, Delate  T, Martinez  K, Clark  NP.  Adherence to and persistence with direct oral anticoagulant therapy among patients with new onset venous thromboembolism receiving extended anticoagulant therapy and followed by a centralized anticoagulation service.   Thromb Res. 2020;193:40-44. doi:10.1016/j.thromres.2020.05.036PubMedGoogle ScholarCrossref

3.

Spyropoulos  AC, Ageno  W, Albers  GW,  et al; MARINER Investigators.  Rivaroxaban for thromboprophylaxis after hospitalization for medical illness.   N Engl J Med. 2018;379(12):1118-1127. doi:10.1056/NEJMoa1805090PubMedGoogle ScholarCrossref

4.

Roberts  LN, Whyte  MB, Georgiou  L,  et al.  Postdischarge venous thromboembolism following hospital admission with COVID-19.   Blood. 2020;136(11):1347-1350. doi:10.1182/blood.2020008086PubMedGoogle ScholarCrossref

5.

Moores  LK, Tritschler  T, Brosnahan  S,  et al.  Prevention, diagnosis, and treatment of VTE in patients with coronavirus disease 2019: CHEST guideline and expert panel report.   Chest. 2020;158(3):1143-1163. doi:10.1016/j.chest.2020.05.559PubMedGoogle ScholarCrossref

6.

Gerotziafas  GT, Catalano  M, Colgan  MP,  et al; Scientific Reviewer Committee.  Guidance for the management of patients with vascular disease or cardiovascular risk factors and COVID-19: position paper from VAS-European Independent Foundation in Angiology/Vascular Medicine.   Thromb Haemost. 2020;120(12):1597-1628. doi:10.1055/s-0040-1715798PubMedGoogle ScholarCrossref

Fireflies have a potential -- protective 'musical armor' against bats

How do fireflies defend themselves against predators?

TEL-AVIV UNIVERSITY

Research News

 

IMAGE: NEW STUDY REVEALS: FIREFLIES PRODUCE STRONG ULTRASONIC SOUNDS THAT MIGHT DETER BATS, POTENTIALLY SERVING AS A KIND OF 'MUSICAL ARMOR' AGAINST THESE PREDATORS. view more 

CREDIT: BRANDON ALMS

A new study at Tel Aviv University reveals a possible defense mechanism developed by fireflies for protection against bats that might prey on them. According to the study, fireflies produce strong ultrasonic sounds - soundwaves that the human ear, and more importantly the fireflies themselves, cannot detect. The researchers hypothesize that these sounds are meant for the ears of bats, keeping them away from the poisonous fireflies, and thereby serving as a kind of 'musical armor'. The study was led by Prof. Yossi Yovel, Head of the Sagol School of Neuroscience, and a member of the School of Mechanical Engineering and the School of Zoology at the George S. Wise Faculty of Life Sciences. It was conducted in collaboration with the Vietnam Academy of Science and Technology (VAST). The paper was published in iScience.

Fireflies are known for their unique glow, used as a mating signal. Since their bodies contain poison, the light flashes probably also serve as an aposematic signal (a warning to potential predators). This signal is also the firefly's weakness, simply because it makes it an easy target for predators. Bats are among the fireflies' most prevalent potential predators, and some bats have poor vision, rendering the flashing signal ineffective. This led the researchers to check whether fireflies had some additional layer of protection against bats.

Prof. Yossi Yovel explains that the idea for this study came up accidentally, during a study that tracked bats' echolocation. "We were wandering around a tropical forest with microphones capable of recording bats' high frequencies, when suddenly, we detected unfamiliar sounds at similar frequencies, coming from fireflies," he recalls. "In-depth research using high-speed video revealed that the fireflies produce the sound by moving their wings, and that the fireflies themselves can't hear this frequency. Consequently we hypothesized that the sound is not intended for any internal communication within the species," adds Ksenia Krivoruchku, the PhD student who led the study.

Following the accidental discovery, the team at Prof. Yovel's laboratory examined three different species of fireflies that are common in Vietnam (Curtos Luciola, Sclerotia) plus one Israeli species (Lampyroidea), and found that they all produce these unique ultrasonic sounds, but cannot hear them.

Can it be concluded that fireflies have developed a special defense mechanism specifically for bats? Prof. Yovel emphasizes that this claim was not proved in the study, but several features do point to this conclusion. First of all, the fact that the fireflies themselves can't hear the sound, while bats can both hear it and use it to find the fireflies - so it's more likely that it serves as a warning signal. Krivoruochku adds that the discovery of ultrasonic sounds in fireflies is in itself an important contribution to the study of predator-prey relations: "The idea of warning signals that the sender itself cannot detect is known from the world of plants but is quite rare among animals. Our discovery of the 'musical battle' between fireflies and bats may pave the way for further research, and possibly the discovery of a new defense mechanism developed by animals against potential predators."

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Adult nocturnal fishflies found to visit flowers for food

KUMAMOTO UNIVERSITY

Research News

IMAGE: A) SCANNING ELECTRON MICROSCOPE (SEM) IMAGE OF POLLEN GRAIN COLLECTED FROM THE BODY SURFACE OF AN AMAMI FISHFLY.
B) SEM IMAGES OF POLLEN GRAINS COLLECTED FROM THE FLOWER OF AN... view more 

CREDIT: ASSOCIATE PROFESSOR NAOTO SUGIURAResearchers from Kumamoto University (Japan) have found that adult nocturnal fishflies (Neochauliodes amamioshimanus), which are typically aquatic insects, feed on pollen at night. They also present circumstantial evidence suggesting that this species not only forages in flowers, but is also a supplementary pollinator. Their work sheds light on the terrestrial life of adult fishflies, which has been a mystery until now.

Megaloptera is a small taxon (about 400 species worldwide) consisting of the families Sialidae (alderflies) and Corydalidae (dobsonflies and fishflies), and is considered to be one of the oldest groups of insects that undergo complete metamorphosis. The biology of the fishfly's aquatic larvae, which were sometimes used as folk remedies in Japan, is relatively well understood. On the other hand, the terrestrial adults are nocturnal, and their behavior in the wild is still a mystery, including what they eat. To date, there have only been brief reports of ingestion of small insects and tree sap. In an effort to learn more about these insects, researchers at Kumamoto University conducted a three-year field study of adult fishflies, which are endemic to Amami Oshima Island in southern Japan.

Dusted yellow

In July 2018, researchers noticed a fine yellow powder covering the front (including the head, pronotum, and legs) of an adult fishfly that flew into a light. A closer examination using scanning electron microscopy revealed that it was pollen from the Iju tree (Schima wallichii ssp. noronhae), a tall tree in the Camelliaceae family. Of the 18 adults (4♂ & 14♀) surveyed between July 2018 and July 2019, 14 (1♂, 13♀) had pollen on them. These included all individuals (1♂, 6♀) found resting on the underside of leaves and walls during the day. The researchers believe that this is because the adults of the species do not use their legs to groom their body surface.

Not just smelling the flowers

In June and July of 2020, researchers collected and examined excrement from 46 adults (17♂, 29♀). Samples from 36 insects (12♂, 24♀) contained Iju pollen, with 7 (3♂, 4♀) having particularly large amounts. This indicates that fishfly adults ingest pollen when visiting flowers. Since captive adults of several fishfly species have been reported to consume liquid nourishment (e.g., sugar water), the researchers speculated that they likely consume the nectar near the base of flower stamens.

Smorgasbord

A total of 27 adults were found in the vicinity of flowering Iju trees on seven nights in June and July 2020, and individual flower visits were confirmed seven times. The insects would stick their heads into the center of the flower, where numerous stamens are densely arranged in a ring, then change positions and do it again resulting in a long stay per flower. One individual spent about 3 minutes on one flower and another spent a total of 11 minutes on two adjacent flowers.

The researchers thus concluded that both sexes of the adult Amami fishfly--named after the island where the study was conducted--have a habit of visiting flowers and feeding on pollen (and nectar). It has long been suggested that some species of diurnal Sialidae visit flowers to forage, but this has never been demonstrated, and no such species is known in the Corydalidae family. This study is the first demonstration in nature that some Megaloptera species are pollen-eaters and have flower-visiting habits.

The fishfly genus, Neochauliodes, consists of 46 species, including the Amami fishfly, and are found in the tropical and temperate zones of Asia. In addition, about 20 species of Iju trees (Schima spp) grow over a large area that overlaps the fishfly habitats. Considering this, it is likely that the pollen feeding behavior is not unique to the Amami fishfly, and may be found in other species of the same genus in other regions. The researchers hope that this work will lead to a gradual elucidation of the terrestrial life of adult fishflies, especially their relationship with plants.

Amami Oshima Island, along with several other islands in the Nansei (Ryukyu) Island chain, is currently a World Natural Heritage Candidate Site recommended by the Japanese government.

"Although the relationship between the fishfly and flowering plants revealed in this study is only a small part of the symbiotic network between the plant and animal species on Amami Oshima Island, it is a case that reminds us, once again, of the great inherent value of biodiversity," said Associate Professor Naoto Sugiura of Kumamoto University, who led this study. "There are few reports of adult aquatic insects functioning as pollinators, and it would be meaningful to clarify whether this species is indeed a pollinator of the Iju tree in the future. If this can be demonstrated, it will be an interesting case study of the clear symbiotic relationship between both aquatic and terrestrial ecosystems."

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This research was posted in Entomological Science on 8 February 2021.

Source:

Sugiura, N., & Miyazaki, S. (2021). Discovery of flower?visiting fishflies: Adult Neochauliodes amamioshimanus (Megaloptera: Corydalidae) nocturnally forages on Schima wallichii ssp. noronhae trees. Entomological Science. doi:10.1111/ens.12463

Development of source technology for the use of wearable devices without recharging

A sponge-type scaffold has been developed through a process involving melting sugar; as it also overcomes performance loss issues, this technology is expected to increase potential for producing high-efficiency flexible thermoelectric devices

NATIONAL RESEARCH COUNCIL OF SCIENCE & TECHNOLOGY

Research News

 

IMAGE: SCHEMATIC OF A PARTIALLY FILLED TEM view more 

CREDIT: KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY(KIST)

Despite the continued development and commercialization of various wearable electronic devices, such as smart bands, progress with these devices has been curbed by one major limitation, as they regularly need to be recharged. However, a new technology developed by a South Korean research team has become a hot topic, as it shows significant potential to overcome this limitation for wearable electronic devices.

The Korea Institute of Science and Technology (KIST), or KIST, announced that a research team led by Director Jin-Sang Kim of the Jeonbuk Institute of Advanced Composite Materials has developed a high-efficiency flexible thermoelectric device that is capable of autonomously generating some of the electricity required for its operation from body heat. The device developed by the team features enhanced thermal insulation capabilities, made possible through the fabrication of the flexible silicone compound (PDMS) into a sponge-like configuration, which was then used as a framework for innovatively enhancing the device's performance.

Thermoelectric devices are able to generate electricity by utilizing the difference in temperature between the two ends of the device, and have been used as eco-friendly generators of power from sources such as vehicle engine heat or waste heat from power plants. Conversely, by instead applying electricity to the thermoelectric device, one end of the device can be cooled while the other generates heat, enabling them to also be used in temperature control systems for small refrigerators, vehicle cooling sheets, and semiconductor equipment.

Normal thermoelectric devices commonly have a rigid ceramic substrate supporting the thermoelectric semiconductor, making them difficult to use on curved surfaces, whereas in flexible thermoelectric devices, a polymer material encapsulates the thermoelectric semiconductor, as opposed to a ceramic substrate, allowing the device to be bent easily. When such a device is worn on the body, electricity can be autonomously generated, and it can also potentially be used as a portable air conditioner. As a result, flexible thermoelectric devices have been garnering much attention in the field of wearable electronic devices. However, the polymer materials used to produce the flexible substrate have a high thermal conductivity, and therefore cannot block heat at both ends of the device. Consequently, the flexible devices that have been produced so far have had the fatal shortcoming of not being able to perform at a level comparable to commercial thermoelectric devices with a rigid substrate.

In pursuing a solution to this issue, the research team at KIST fabricated a sponge-configuration polymer material, by first pouring a silicone compound solution onto a sugar cube and allowing the solution to solidify, and then dissolving the sugar cube in water. Consequently, as the sugar cube dissolved, the space which had been occupied by the cube was transformed into a structure consisting of micro air bubbles. The thermal insulation capability of this structure was 50% higher than conventional materials, enabling it to effectively block the transfer of heat. The team at KIST used this substrate as a support frame to develop a flexible thermoelectric device that suffers from no loss of performance. The team's device demonstrated performance that was superior to existing flexible thermoelectric devices by more than 20%, and comparable to existing commercial devices. The research team (including the first co-authors: Dr. Sung-Jin Jung, Dr. Joonchul Shin) was able to successfully use their flexible device to turn on an LED light with body heat.

Director Jin-Sang Kim of the Jeonbuk branch of KIST stated that "the efficiency of our flexible thermoelectric device was raised to a level comparable to that of commercial thermoelectric devices through a simple, inexpensive process that requires pouring a solution on sugar and allowing the solution to solidify." He also commented, "if we used a sufficient number of thermoelectric devices, it should certainly be possible to produce smart bands that operate on body heat alone."

CAPTION

A photographic image of the flexible TEM based on porous PDMS filler

CREDIT

Korea Institute of Science and Technology(KIST)

 

This research project was conducted as part of the National Research Council of Science & Technology's Creative Allied Project, as well as the Creative Materials Discovery Program headed by the National Research Foundation of Korea and supported by the Ministry of Science and ICT (MSIT). The findings of this study were published in the March edition of the international journal "Nano Energy."

 

People do not learn from regretting one night stands

Regret doesn't seem to help you avoid making the same mistake again

NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY

Research News

 

A lot of people think regret must be a good thing because it helps you not repeat a mistake, right?

But that turns out not to be the case. Not even when it comes to casual sex, according to new research from the Norwegian University of Science and Technology's (NTNU) Department of Psychology.

"For the most part, people continue with the same sexual behaviour and the same level of regret," says Professor Leif Edward Ottesen Kennair.

So, we repeat what we thought was a mistake, and we regret it just as much the next time around.

Professor Kennair and colleagues professor Mons Bendixen and postdoctoral fellow Trond Viggo Grøntvedt have investigated whether sexual regret is functional, that is, whether it contributes to any change in behaviour.

The participants in the study answered a questionnaire about sexual regret two times, at approximately 4.5 month intervals. This approach makes it possible to study changes over shorter periods of time.

Both women and men might regret what they did the last time an opportunity for casual sex arose. But they often regret completely different choices.

Women tend to regret having had casual sex more than men. Men, on the other hand, regret not taking advantage of a casual sex opportunity markedly more than women.

"We wanted to examine if their level of regret contributed to a change in behaviour the next time around," says Bendixen.

"A lot of emotions are functional, like disgust that protects against infection and fear that protects against danger. An evolutionary approach has helped us understand anxiety by understanding the function of fear: fight-flight-freeze is about avoiding danger and defending ourselves against it," says Kennair.

Many people assume that emotions have a function

Many psychologists assume that regret and other emotions have a function: that they'll influence our behaviour so that we modify it. For example, after experiencing negative emotions, we will change our behaviour to reduce the risk of having those negative feelings later.

"Researchers have found that most people believe this is true for regret. They assume that regret is actually a helpful negative feeling. People assume it guides them not to repeat what they regretted," says Grøntvedt.

If regret works that way, then wouldn't men more often have casual sex the next time the opportunity arose? And, you would think that women's regret would lead them to choose better partners, have less frequent casual sex or try harder to get into steady relationships.

But no, that's not what happens. The findings from the study show that we don't learn from what we perceived as a mistake.

So why is that? Why don't we learn from our mistakes?

Probably because our behaviour depends on our personality, which is something quite different and more complicated than a shorter or more prolonged feeling of regret.

We are mostly just who we are, and when the opportunity arises and horniness take over, or doesn't, we probably react just like the time before.

"We are not that surprised," Kennair says. "If regret helped, would not most sinners eventually become saints? What do you regret the most often? Has it changed your behaviour?" he asks.

Regret is flexible, not constant. Or, as psychologists say, regret is adaptive. It changes according to the conditions.

"We have repeated that regret is adaptive in all our articles on the subject in recent years. And now we have tested it," says Kennair.

No one else has tested regret for sexual behaviour. Perhaps researchers have assumed that they knew enough? Even outstanding people in the field have assumed that regret would help us learn.

"We found little information on this topic. But both most researchers and people in general believe that regret is wise," says Grøntvedt.

Do you really need to spend so much time being regretful?

"Maybe it would be smart instead to think about what we regret in everyday life, and what we actually do so often that we get ample opportunity to regret it," Kennair says.

Have you exercised enough lately? Did you eat too much? Done everything you should? Said something you shouldn't have said? Does it help to regret things sometimes? No? This is a bit like ruminating, which a lot of people with depression assume is a smart thing to do, even if they become more depressed from doing it.

"And yet, there are some folks who think that depressive ruminating and worry are a good idea. But the way we treat depression and generalized anxiety disorders is by helping people to stop ruminating and to stop worrying. Not everything people do, think or feel is an evolutionary adaptation - sometimes it is not appropriate either," Kennair says.

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