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Going small for big solutions: Sub-nanoparticle catalysts made from coinage elements as effective catalysts

Due to their small size, nanoparticles find varied applications in fields ranging from medicine to electronics. Their small size allows them a high reactivity and semiconducting property not found in the bulk states. Sub-nanoparticles (SNPs) have an extremely small diameter of around 1 nm, making them even smaller than nanoparticles. Almost all atoms of SNPs are available and exposed for reactions, and therefore, SNPs are expected to have extraordinary functions beyond the properties of nanoparticles, particularly as catalysts for industrial reactions. However, preparation of SNPs requires fine control of the size and composition of each particle on a sub-nanometer scale, making the application of conventional production methods near impossible.

To overcome this, researchers at the Tokyo Institute of Technology led by Dr. Takamasa Tsukamoto and Prof. Kimihisa Yamamoto previously developed the atom hybridization method (AHM) which surpasses the previous trials of SNP synthesis. Using this technique, it is possible to precisely control and diversely design the size and composition of the SNPs using a “macromolecular template” called phenylazomethine dendrimer. This improves their catalytic activity than the NP catalysts.

Now, in their latest study published in Angewandte Chemie International Edition, the team has taken their research one step further and has investigated the chemical reactivity of alloy SNPs obtained through the AHM. “We created monometallic, bimetallic, and trimetallic SNPs (containing one, combination of two, and combination of three metals respectively), all composed of coinage metal elements (copper, silver, and gold), and tested each to see how good of a catalyst each of them is,” reports Dr Tsukamoto. 

Unlike corresponding nanoparticles, the SNPs created were found to be stable and more effective. Moreover, SNPs showed a high catalytic performance even under the milder conditions, in direct contrast to conventional catalysts. Monometallic, bimetallic, and trimetallic SNPs demonstrated the formation of different products, and this hybridization or combination of metals seemed to show a higher turnover frequency (TOF). The trimetallic combination “Au4Ag8Cu16” showed the highest TOF because each metal element plays a unique role, and these effects work in concert to contribute to high reaction activity.

Furthermore, SNP selectively created hydroperoxide, which is a high-energy compound that cannot be normally obtained due to instability. Mild reactions without high temperature and pressure realized in SNP catalysts resulted in the stable formation of hydroperoxide by suppressing its decomposition.

When asked about the relevance of these findings, Prof Yamamoto states: “We demonstrate for the first time ever, that olefin hydroperoxygenation can been catalyzed under extremely mild conditions using metal particles in the quantum size range. The reactivity was significantly improved in the alloyed systems especially for the trimetallic combinations, which has not been studied previously.”

The team emphasized that because of the extreme miniaturization of the structures and the hybridization of different elements, the coinage metals acquired a high enough reactivity to catalyze the oxidation even under the mild condition. These findings will prove to be a pioneering key in the discovery of innovative sub-nanomaterials from a wide variety of elements and can solve energy crises and environmental problems in the years to come.

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ESPRESSO confirms the presence of an Earth around the nearest star

The existence of a planet the size of Earth around the closest star in the solar system, Proxima Centauri, has been confirmed by an international team of scientists including researchers from the University of Geneva (UNIGE). The results, which you can read all about in the journal Astronomy & Astrophysics, reveal that the planet in question, Proxima b, has a mass of 1.17 earth masses and is located in the habitable zone of its star, which it orbits in 11.2 days. This breakthrough has been possible thanks to radial velocity measurements of unprecedented precision using ESPRESSO, the Swiss-manufactured spectrograph — the most accurate currently in operation — which is installed on the Very Large Telescope in Chile. Proxima b was first detected four years ago by means of an older spectrograph, HARPS — also developed by the Geneva-based team — which measured a low disturbance in the star’s speed, suggesting the presence of a companion.

The ESPRESSO spectrograph has performed radial velocity measurements on the star Proxima Centauri, which is only 4.2 light-years from the Sun, with an accuracy of 30 centimetres a second (cm/s) or about three times more precise than that obtained with HARPS, the same type of instrument but from the previous generation.

“We were already very happy with the performance of HARPS, which has been responsible for discovering hundreds of exoplanets over the last 17 years,” begins Francesco Pepe, a professor in the Astronomy Department in UNIGE’s Faculty of Science and the man in charge of ESPRESSO. “We’re really pleased that ESPRESSO can produce even better measurements, and it’s gratifying and just reward for the teamwork lasting nearly 10 years.”

Alejandro Suarez Mascareño, the article’s main author, adds: “Confirming the existence of Proxima b was an important task, and it’s one of the most interesting planets known in the solar neighbourhood.”

The measurements performed by ESPRESSO have clarified that the minimum mass of Proxima b is 1.17 earth masses (the previous estimate was 1.3) and that it orbits around its star in only 11.2 days.

“ESPRESSO has made it possible to measure the mass of the planet with a precision of over one-tenth of the mass of Earth,” says Michel Mayor, winner of the Nobel Prize for Physics in 2019, honorary professor in the Faculty of Science and the ‘architect’ of all ESPRESSO-type instruments. “It’s completely unheard of.”

And what about life in all this?

Although Proxima b is about 20 times closer to its star than the Earth is to the Sun, it receives comparable energy, so that its surface temperature could mean that water (if there is any) is in liquid form in places and might, therefore, harbour life.

Having said that, although Proxima b is an ideal candidate for biomarker research, there is still a long way to go before we can suggest that life has been able to develop on its surface. In fact, the Proxima star is an active red dwarf that bombards its planet with X rays, receiving about 400 times more than the Earth.

“Is there an atmosphere that protects the planet from these deadly rays?” asks Christophe Lovis, a researcher in UNIGE’s Astronomy Department and responsible for ESPRESSO’s scientific performance and data processing. “And if this atmosphere exists, does it contain the chemical elements that promote the development of life (oxygen, for example)? How long have these favourable conditions existed? We’re going to tackle all these questions, especially with the help of future instruments like the RISTRETTO spectrometer, which we’re going to build specially to detect the light emitted by Proxima b, and HIRES, which will be installed on the future ELT 39 m giant telescope that the European Southern Observatory (ESO) is building in Chile.”

Surprise: is there a second planet?

In the meantime, the precision of the measurements made by ESPRESSO could result in another surprise. The team has found evidence of a second signal in the data, without being able to establish the definitive cause behind it. “If the signal was planetary in origin, this potential other planet accompanying Proxima b would have a mass less than one third of the mass of the Earth. It would then be the smallest planet ever measured using the radial velocity method,” adds Professor Pepe.

It should be noted that ESPRESSO, which became operational in 2017, is in its infancy and these initial results are already opening up undreamt of opportunities. The road has been travelled at breakneck pace since the first extrasolar planet was discovered by Michel Mayor and Didier Queloz, both from UNIGE’s Astronomy Department. In 1995, the 51Peg b gas giant planet was detected using the ELODIE spectrograph with an accuracy of 10 meters per second (m/s). Today ESPRESSO, with its 30 cm/s (and soon 10 after the latest adjustments) will perhaps make it possible to explore worlds that remind us of the Earth.

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AI to make dentists’ work easier

In order to plan a dental implant operation and the implant size and position, dentists need to know the exact location of the mandibular canal, a canal located in both sides of the lower jaw that contains the alveolar nerve.

The lower jaw is an anatomically complex structure and medical experts use X-ray and computer tomography (CT) models to detect and diagnose such structures. Typically, dentists and radiologists define the location of the mandibular canals manually from the X-ray or CT scans, which makes the task laborious and time-consuming. That is why an automatized way to do this could make their work and placement of dental implants much easier.

To bring a solution to this problem, researchers at the Finnish Center for Artificial Intelligence FCAI, Tampere University Hospital, Planmeca and the Alan Turing Institute developed a new model that accurately and automatically shows the exact location of mandibular canals. The model is based on training and using deep neural networks. The researchers trained the model by using a dataset consisting of 3D cone beam CT (CBCT) scans.

The model is based on a fully convolutional architecture, which makes it as fast and data-efficient as possible. Based on the research results, this type of a deep learning model can localise the mandibular canals highly accurately. It surpasses the statistical shape models, which have thus far been the best, automatized method to localise the mandibular canals.

In simple cases — when the patient does not have any special conditions, such as osteoporosis — the model is as accurate as a human specialist. Most patients that visit a dentist fall into this category. ‘In more complex cases, one may need to adjust the estimate, so we are not yet talking about a fully stand-alone system,’ says Joel Jaskari, Doctoral Candidate and the first author of the research paper.

Using Artificial Intelligence has another clear advantage, namely the fact that the machine performs the job equally fast and accurately every time. ‘The aim of this research work is not, however, to replace radiologists but to make their job faster and more efficient so that they will have time to focus on the most complex cases,’ adds Professor Kimmo Kaski.

Planmeca, a Finnish company developing, manufacturing and marketing dental equipment, 2D and 3D imaging equipment and software, collaborates with FCAI. The company is currently integrating the presented model into its dedicated software, to be used with Planmeca 3D tomography equipment.

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Large exoplanet could have the right conditions for life

Astronomers have found an exoplanet more than twice the size of Earth to be potentially habitable, opening the search for life to planets significantly larger than Earth but smaller than Neptune.

A team from the University of Cambridge used the mass, radius, and atmospheric data of the exoplanet K2-18b and determined that it’s possible for the planet to host liquid water at habitable conditions beneath its hydrogen-rich atmosphere. The results are reported in The Astrophysical Journal Letters.

The exoplanet K2-18b, 124 light-years away, is 2.6 times the radius and 8.6 times the mass of Earth, and orbits its star within the habitable zone, where temperatures could allow liquid water to exist. The planet was the subject of significant media coverage in the autumn of 2019, as two different teams reported detection of water vapour in its hydrogen-rich atmosphere. However, the extent of the atmosphere and the conditions of the interior underneath remained unknown.

“Water vapour has been detected in the atmospheres of a number of exoplanets but, even if the planet is in the habitable zone, that doesn’t necessarily mean there are habitable conditions on the surface,” said Dr Nikku Madhusudhan from Cambridge’s Institute of Astronomy, who led the new research. “To establish the prospects for habitability, it is important to obtain a unified understanding of the interior and atmospheric conditions on the planet — in particular, whether liquid water can exist beneath the atmosphere.”

Given the large size of K2-18b, it has been suggested that it would be more like a smaller version of Neptune than a larger version of Earth. A ‘mini-Neptune’ is expected to have a significant hydrogen ‘envelope’ surrounding a layer of high-pressure water, with an inner core of rock and iron. If the hydrogen envelope is too thick, the temperature and pressure at the surface of the water layer beneath would be far too great to support life.

Now, Madhusudhan and his team have shown that despite the size of K2-18b, its hydrogen envelope is not necessarily too thick and the water layer could have the right conditions to support life. They used the existing observations of the atmosphere, as well as the mass and radius, to determine the composition and structure of both the atmosphere and interior using detailed numerical models and statistical methods to explain the data.

The researchers confirmed the atmosphere to be hydrogen-rich with a significant amount of water vapour. They also found that levels of other chemicals such as methane and ammonia were lower than expected for such an atmosphere. Whether these levels can be attributed to biological processes remains to be seen.

The team then used the atmospheric properties as boundary conditions for models of the planetary interior. They explored a wide range of models that could explain the atmospheric properties as well as the mass and radius of the planet. This allowed them to obtain the range of possible conditions in the interior, including the extent of the hydrogen envelope and the temperatures and pressures in the water layer.

“We wanted to know the thickness of the hydrogen envelope — how deep the hydrogen goes,” said co-author Matthew Nixon, a PhD student at the Institute of Astronomy. “While this is a question with multiple solutions, we’ve shown that you don’t need much hydrogen to explain all the observations together.”

The researchers found that the maximum extent of the hydrogen envelope allowed by the data is around 6% of the planet’s mass, though most of the solutions require much less. The minimum amount of hydrogen is about one-millionth by mass, similar to the mass fraction of the Earth’s atmosphere. In particular, a number of scenarios allow for an ocean world, with liquid water below the atmosphere at pressures and temperatures similar to those found in Earth’s oceans.

This study opens the search for habitable conditions and bio-signatures outside the solar system to exoplanets that are significantly larger than Earth, beyond Earth-like exoplanets. Additionally, planets such as K2-18b are more accessible to atmospheric observations with current and future observational facilities. The atmospheric constraints obtained in this study can be refined using future observations with large facilities such as the upcoming James Webb Space Telescope.

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How big is the neutron?

The size of neutrons cannot be measured directly: it can only be determined from experiments involving other particles. While such calculations have so far been made in a very indirect way using old measurements with heavy atoms, a team at the Institute of Theoretical Physics at Ruhr-Universität Bochum (RUB) has taken a different approach. By combining their very accurate calculations with recent measurements on light nuclei, the researchers have arrived at a more direct methodology.

Their results, which differ significantly from previous ones, are described by the researchers headed by Professor Evgeny Epelbaum in the journal Physical Review Letters from 25. February 2020.

Neutrons and protons, jointly referred to as nucleons, form atomic nuclei and are therefore among the most common particles in our universe. The nucleons themselves consist of strongly interacting quarks and gluons and have a complex internal structure, the precise understanding of which is the subject of active research. One of the fundamental properties of nucleons is their size as determined by charge distribution. “Inside, there are positive and negative charge regions which, when taken together, result in zero total charge for the neutron,” explains Evgeny Epelbaum. “The neutron’s radius can be thought of as the spatial extension of the charge distribution. It thus determines the size of the neutrons.”

A very indirect method

To date, determinations of this quantity were based on scattering experiments with extremely low-energy neutrons on an electron shell of heavy atoms such as bismuth. “Researchers would direct such a neutron beam at a target of heavy isotopes carrying many electrons and determine how many neutrons passed through,” says Bochum-based physicist Dr. Arseniy Filin. This allowed one to extract the size of the neutrons. “This is a very indirect method,” points out the physicist.

In their current project, the group has for the first time determined the neutron charge radius from the lightest atomic nuclei. In a theoretical study, they have succeeded in calculating the deuteron radius with high accuracy. The deuteron is one of the simplest atomic nuclei and consists of one proton and one neutron. Since the two nucleons in the deuteron are relatively far apart, the deuteron turns out to be much larger than its two constituents. “Our accurate prediction of the deuteron radius, combined with high-precision spectroscopic measurements of the deuteron-proton radius difference, yielded a value for the neutron radius that is about 1.7 standard deviations off the previous determinations,” concludes Dr. Vadim Baru from the Helmholtz Institute for Radiation and Nuclear Physics at the University of Bonn. Accordingly, the previously assumed value for the size of a neutron is to be corrected.

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‘Wristwatch’ monitors body chemistry to boost athletic performance, prevent injury

Engineering researchers have developed a device the size of a wristwatch that can monitor an individual’s body chemistry to help improve athletic performance and identify potential health problems. The device can be used for everything from detecting dehydration to tracking athletic recovery, with applications ranging from military training to competitive sports.

“This technology allows us to test for a wide range of metabolites in almost real time,” says Michael Daniele, co-corresponding author of a paper on the work and an assistant professor of electrical and computer engineering at North Carolina State University and in the Joint Department of Biomedical Engineering at NC State and the University of North Carolina at Chapel Hill.

Metabolites are markers that can be monitored to assess an individual’s metabolism. So, if someone’s metabolite levels are outside of normal parameters, it could let trainers or health professionals know that something’s wrong. For athletes, it could also be used to help tailor training efforts to improve physical performance.

“For this proof-of-concept study, we tested sweat from human participants and monitored for glucose, lactate, pH and temperature,” Daniele says.

A replaceable strip on the back of the device is embedded with chemical sensors. That strip rests against a user’s skin, where it comes into contact with the user’s sweat. Data from the sensors in the strip are interpreted by hardware inside the device, which then records the results and relays them to a user’s smartphone or smartwatch.

“The device is the size of an average watch, but contains analytical equipment equivalent to four of the bulky electrochemistry devices currently used to measure metabolite levels in the lab,” Daniele says. “We’ve made something that is truly portable, so that it can be used in the field.”

While the work for this paper focused on measuring glucose, lactate and pH, the sensor strips could be customized to monitor for other substances that can be markers for health and athletic performance — such as electrolytes.

“We’re optimistic that this hardware could enable new technologies to reduce casualties during military or athletic training, by spotting health problems before they become critical,” Daniele says. “It could also improve training by allowing users to track their performance over time. For example, what combination of diet and other variables improves a user’s ability to perform?”

The researchers are now running a study to further test the technology when it is being worn by people under a variety of conditions.

“We want to confirm that it can provide continuous monitoring when in use for an extended period of time,” Daniele says.

“While it’s difficult to estimate what the device might cost consumers, it only costs tens of dollars to make. And the cost of the strips — which can last for at least a day — should be comparable to the glucose strips used by people with diabetes.

“We’re currently looking for industry partners to help us explore commercialization options for this technology,” Daniele says.

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Quantum Dots Encode Vaccine History in the Skin

I remember a faded yellow booklet, about the size of a wallet, that my mother used to pull out once a year at the doctor’s office to record my vaccines. Today, nurses document my children’s vaccination history in electronic health records that will likely follow them to adulthood.

To eradicate a disease—such as polio or measles—healthcare workers need to know who was vaccinated and when. Yet in developing countries, vaccination records are sparse and, in some cases, non-existent. For example, during a rural vaccination campaign, a healthcare worker may mark a child’s fingernail with a Sharpie, which can wash or scrape off within days.

Now, a team of MIT bioengineers has developed a way to keep invisible vaccine records under the skin. Delivered through a microneedle patch, biocompatible quantum dots embed in the skin and fluoresce under near-infrared light—creating a glowing trace that can be detected at least five years after vaccination. The work is described today in the journal Science Translational Medicine.  

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Wading Bird Colony Location, Size, and Timing in the Everglades

Funding Opportunity ID: 322580
Opportunity Number: W81EWF-20-SOI-0005
Opportunity Title: Wading Bird Colony Location, Size, and Timing in the Everglades
Opportunity Category: Discretionary
Opportunity Category Explanation:
Funding Instrument Type: Cooperative Agreement
Category of Funding Activity: Science and Technology and other Research and Development
Category Explanation:
CFDA Number(s): 12.630
Eligible Applicants: Others (see text field entitled “Additional Information on Eligibility” for clarification)
Additional Information on Eligibility: This opportunity is restricted to Non-Federal Partners of the South Florida – Caribbean Cooperative Ecosystem Studies Unit (CESU).
Agency Code: DOD-COE
Agency Name: Department of Defense
Dept. of the Army — Corps of Engineers
Posted Date: Nov 18, 2019
Close Date: Dec 17, 2019
Last Updated Date: Nov 18, 2019
Award Ceiling: $625,380
Award Floor: $0
Estimated Total Program Funding:
Expected Number of Awards: 1
Description: Wading Bird Colony Location, Size, and Timing in the Everglades
Version: 1

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New ultra-miniaturized scope less invasive, produces higher quality images

Johns Hopkins engineers have created a new lens-free ultra-miniaturized endoscope, the size of a few human hairs in width, that is less bulky and can produce higher quality images.

Their findings were published today in Science Advances.

“Usually, you have sacrifice either size or image quality. We’ve been able to achieve both with our microendoscope,” says Mark Foster, an associate professor of electrical and computer engineering at The Johns Hopkins University and the study’s corresponding author.

Intended for examining neurons firing off in the brains of animals such as mice and rats, an ideal microendoscope should be small to minimize brain tissue damage yet powerful enough to produce a clear image.

Currently, standard microendoscopes are about half a millimeter to a few millimeters in diameter, and require larger, more invasive lenses for better imaging. While lensless microendoscopes exist, the optical fiber within that scans an area pixel by pixel frequently bends and loses imaging ability when moved.

In their new study, Foster and colleagues created a lens-free ultra-miniaturized microendoscope that, compared to a conventional lens-based microendoscope, increases the amount researchers can see and improves image quality.

The researchers achieved this by using a coded aperture, or a flat grid that randomly blocks light creating a projection in a known pattern akin to randomly poking a piece of aluminum foil and letting light through all of the small holes. This creates a messy image, but one that provides a bounty of information about where the light originates, and that information can be computationally reconstructed into a clearer image. In their experiments, Foster’s team looked at beads in different patterns on a slide.

“For thousands of years, the goal has been to make an image as clear as possible. Now, thanks to computational reconstruction, we can purposefully capture something that looks awful and counterintuitively end up with a clearer final image,” says Foster.

Additionally, Foster and team’s microendoscope doesn’t require movement to focus on objects at different depths; they use computational refocusing to determine where the light originated from in 3 dimensions. This allows the endoscope to be much smaller than a traditional one that requires moving the endoscope around to focus.

Looking forward, the research team will test their microendoscope with fluorescent labeling procedures in which active brain neurons would be tagged and illuminated, to determine how accurately the endoscope can image neural activity.

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Larger than life: Augmented ants

An ant the size of a lion isn’t as far-fetched as you would think. From as small as a sesame seed to the size of a big cat, ants come in all sizes — in augmented reality, at least.

Augmented reality provides an interactive experience of the ‘real world’ with the help of computer-generated images viewed through a screen. It’s a technology often used in videogames to meld computer-generated images with reality. Now researchers in the Biodiversity and Biocomplexity Unit at the Okinawa Institute of Science and Technology Graduate University (OIST) have used this high tech approach to create the first ever augmented reality experience that pairs with a taxonomic research paper. The research, published in Insect Systematics and Diversity, presents six new species of Strumigenys ants, also known as miniature trap-jaw ants, from Fiji.

“In our lab we have been working on tools to interact with biodiversity data in different ways,” said Prof. Evan Economo, senior author of the study. “The specimens we study are locked away in natural history museums, and not easily accessible to both researchers and the general public.”

The ant specimens are now accessible anywhere and everywhere with the interactive taxonomic app, Insects3D. The scientists used 3D x-ray scans to create digital models of the ants. Insects3D allows a user to view 3D models of ant specimens in augmented reality and lets them place ants in the real world using the app. Users can even magnify the species to the size of a lion if they please.

“When we made the app I gave it to my five-year old son,” Economo said. “He spent an hour running around the house putting ants everywhere.”

It’s not just Economo’s son — augmented reality allows new scientific experiences for a broad range of people. This app allows those from all corners of the world to engage with the same data. All you need is an iPhone. Economo believes this technology will ignite a new way of experiencing research.

“With this app, we hope to get more people interested and help everyone see what the potential could be in the future,” Economo said. “We have six [ant] models and geographic maps of where they are found. It’s just the beginning and we are excited by what’s to come.”

The new biodiversity data on the ants are a detailed description of the anatomy of each species, including their unusual trap-like mandibles. The ant is in a global group that appears to have undergone adaptive radiation in Fiji. This radiation occurs when one evolutionary lineage splits into multiple species, thus diversifying. Economo and first author on the paper, Eli Sarnat, started their fieldwork in 2004. 23 species from their collecting are presented in the paper and six represent new species discovered for the first time. Economo and Sarnat didn’t expect one-third of the species they collected to be new to science since Fiji is a small remote archipelago.

“The main research of the lab is understanding the evolution of insect diversity around the world, and new species discovery is a part of that,” Economo said. “Rather than just describing new species in papers very few will read, we are interested to push the boundaries of technology and how we share results with our colleagues and the public.”

Pushing boundaries is nothing new in science. This technology extends beyond taxonomic research use — researchers in other disciplines can use this approach to explore new ways to display their scientific discoveries.

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