First Detailed Look At How Molecular Ferris Wheel Delivers Protons To Cellular Factories (Biology)

No human cell can function without these tiny machines, which cause disease when they go haywire and offer potential targets for therapeutic drugs.

All cells with nuclei, from yeast to humans, are organized like cities, with a variety of small compartments – organelles – that serve as factories where various types of work are done. Some of those factories, like the ones that break down and recycle molecules, need to continually pump in protons – hydrogen atoms with their electrons stripped off – to maintain the acidic environment they need to do their job. For this they rely on molecular Ferris wheels.

A molecular machine for pumping protons. An animation shows a proton pump called V-ATPase at work. These pumps are embedded in the membranes of cellular organelles, where they bring in protons that are essential for the organelle’s function. The top part of the pump generates energy to drive the rotating part at the bottom, which is like a molecular Ferris wheel that picks up protons on the outside of the organelle and drops them off inside. Scientists at SLAC National Accelerator Laboratory, Stanford University, SUNY Upstate Medical University and Arizona State University used cryo-EM images and computer simulations to reveal key details about how the pump works. ©From the labs of S.-H. Roh and S. Wilkens

Embedded in the organelle’s fatty outer membrane, these microscopic machines have rotors that spin 100 times per second, picking up protons from outside the organelle and dropping them off on the inside.

Now scientists have figured out a key step in how these Ferris wheels work in a yeast proton pump known as vacuolar ATPase (V-ATPase). The results of their study, which combined high-resolution images made at the Department of Energy’s SLAC National Accelerator Laboratory with supercomputer simulations, were published in Science Advances today, giving scientists insight into a fundamental process that could potentially be harnessed to thwart disease.

A Proton Ferris Wheel In action: This animation, based on simulations and cryo-EM images, shows a top-down view of the V-ATPase proton pump Ferris wheel as it rotates clockwise. As each Ferris wheel seat arrives at the drop-off point – at the top of the rotation here – its proton passenger hops off and is guided by water molecules to its destination in the organelle’s interior (green ribbons). A study by researchers from SLAC National Accelerator Laboratory, Stanford University, SUNY Upstate Medical University and Arizona State University revealed key details of this drop-off. ©S.-H.Roh et al., Science Advances, 7 October 2020

“The V-ATPase proton pumps perform a wide range of functions, from helping transmit nerve signals to helping specialized cells secrete acid for maintaining bone,” said Stephan Wilkens, a biochemist at SUNY Upstate Medical University and study co-author. “Malfunctions in these molecular machines contribute to diseases such as osteoporosis, neurodegeneration, diabetes, cancer and AIDS, so understanding them is important for human health.”

Wah Chiu, a professor at SLAC and Stanford and co-director of the Stanford-SLAC Cryo-EM Facilities where the imaging was done, said scientists are already investigating how these pumps in human cells might affect replication of the COVID-19-causing virus in patients. “It turns out the majority of therapeutic drugs on the market target molecular machines like this one that sit in cell membranes,” he added.

Watching the wheel go round

No human cell can function without proton pumps, which among other things help organelles intercept viruses and other pathogens and divert them to cellular trash bins.

While previous studies had determined the molecular structure and basic function of V-ATPases in a number of organisms, Wilkens said, “the big question was how do they work? To explain the mechanism it’s helpful to see it in action, just like the first serial snapshots of a galloping horse finally settled the question of whether it always had at least one hoof on the ground. The answer was no.”

How water molecules form a bucket brigade to ferry protons into organelles (IMAGE) In this illustration, the Ferris wheel part of the V-ATPase proton pump is at the bottom, rotating clockwise, and the inside of the organelle – the drop-off point for protons – is at the top, in green. The zoomed-in view at left depicts a key finding of this study: Scientists from SLAC National Accelerator Laboratory, Stanford University, SUNY Upstate Medical University and Arizona State University confirmed that water molecules form “wires” at the drop-off point that convey protons from their seats on the Ferris wheel to the organelle interior, like a fire brigade passing buckets hand to hand. ©Greg Stewart/SLAC; S.-H. Roh et al.,Science Advances, 7 October 2020

In earlier cryo-EM research, Chiu, Wilkens, SLAC/ Stanford postdoctoral researcher Soung-Hun Roh and others produced high-resolution images that allowed them to identify the 10 amino acid “seats” on the yeast Ferris wheel that bind protons and carry them through the membrane to the organelle’s interior, as well as other amino acids that catch them when they arrive. Based on that picture, they suggested that the proton drop-off might be aided by water molecules, but their images were not sharp enough to confirm that the water molecules were there.

In the current study, thanks to another round of even higher resolution cryo-EM imaging at SLAC they were able to locate the water molecules around the suspected proton path. To make the proton pump motor come to life, a research group led by Abhishek Singharoy at the Arizona State University Biodesign Institute developed computer simulations of the process and ran them on a DOE supercomputer at Oak Ridge National Laboratory.

The simulations, which incorporated cryo-EM structures derived from images of the yeast Ferris wheel captured at two different points in its rotation, confirmed the experimentally observed water molecules lining up to form “wires” at the proton drop-off point. These wires convey protons from their seats on the Ferris wheel to landing spots inside the organelle, like a fire brigade passing buckets hand to hand, bridging a gap they couldn’t navigate on their own.

Going forward, Chiu said, recent advances in cryo-EM that allow imaging of individual particles at atomic resolution – even when they take slightly different shapes – will open new opportunities for using it as a tool to discover effective drugs for illnesses involving proton pumps.

References: Soung Roh, Mrinal Shekhar et al., “Cryo-EM and MD infer water-mediated proton transport and autoinhibition mechanisms of Vo complex”, Science Advances 07 Oct 2020: Vol. 6, no. 41, eabb9605 DOI: 10.1126/sciadv.abb9605 link: https://advances.sciencemag.org/content/6/41/eabb9605

Provided by DOE/ SLAC National Accelerator Laboratory

Sensory Device Stimulates Ears And Tongue To Treat Tinnitus In Large Trial (Medicine)

A device that stimulates the ears and tongue substantially reduced the severity of tinnitus symptoms in 326 patients for as long as 1 year, while achieving high patient satisfaction and adherence. The study – one of the largest clinical trials of a tinnitus treatment to date – indicates the bimodal technique could potentially provide the first effective, clinically viable device for tinnitus, which affects up to 15% of the population. This irritating auditory disorder manifests when patients perceive phantom noises such as ringing without any external input. Despite its high prevalence and potentially debilitating nature, there are no approved medical devices or drug treatments that can provide relief to patients. However, recent research in animals has shown that stimulating the auditory nervous system through sounds and electricity improved symptoms. Based on these promising results, Brendan Conlon and colleagues used a non-invasive stimulating device, which delivers sound to the ears through headphones and stimulates the tongue with low amounts of electricity. In a randomized trial of 326 patients with different types of tinnitus, the authors instructed the patients to use the device for 60 minutes daily for 12 weeks. The device reduced tinnitus symptoms, and these improvements persisted throughout a 12-month follow-up period. The team notes they are currently conducting another large clinical trial to study the effects of changing the stimulation protocol over time.

A schematic showing the bimodal neuromodulation device. Wireless headphones delivered sounds, while a small electrode array stimulated the tongue with different patterns. This material relates to a paper that appeared in the Oct. 7, 2020, issue of Science Translational Medicine, published by AAAS. The paper, by B. Conlon at Neuromod Devices Limited in Dublin, Ireland; and colleagues was titled, “Bimodal neuromodulation combining sound and tongue stimulation reduces tinnitus symptoms in a large randomized clinical study.” ©B. Conlon et al., Science Translational Medicine (2020)
Image depicting the device components. This material relates to a paper that appeared in the Oct. 7, 2020, issue of Science Translational Medicine, published by AAAS. The paper, by B. Conlon at Neuromod Devices Limited in Dublin, Ireland; and colleagues was titled, “Bimodal neuromodulation combining sound and tongue stimulation reduces tinnitus symptoms in a large randomized clinical study.” ©Neuromod Devices Limited
Image depicting a patient using the device. This material relates to a paper that appeared in the Oct. 7, 2020, issue of Science Translational Medicine, published by AAAS. The paper, by B. Conlon at Neuromod Devices Limited in Dublin, Ireland; and colleagues was titled, “Bimodal neuromodulation combining sound and tongue stimulation reduces tinnitus symptoms in a large randomized clinical study.” ©Neuromod Devices Limited

Provided by American Association For The Advancement In Science

Oral Cancer Pain Predicts Likelihood Of Cancer Spreading (Oncology / Medicine)

Research identifies genes highly expressed in painful, metastatic oral cancer, revealing mechanism for cancer pain.

Oral cancer is more likely to spread in patients experiencing high levels of pain, according to a team of researchers at New York University (NYU) College of Dentistry that found genetic and cellular clues as to why metastatic oral cancers are so painful.

The findings–which appear in Scientific Reports, a journal published by Nature–may ultimately be used to alleviate oral cancer pain and refine surgical decision making when treating oral cancer.

Aditi Bhattacharya, PhD, examines oral cancer using a microscope. ©Chuy Gutierrez

Oral cancer can cause severe pain during everyday activities, including talking and eating. Previous research by Brian L. Schmidt, DDS, MD, PhD, director of the NYU Oral Cancer Center and one of the study’s authors, suggests that patients with metastatic oral cancer–cancer that spreads beyond the mouth–experience more pain than those whose cancer has not spread. The new study helps researchers understand why.

When oral cancer metastasizes, spreading to lymph nodes in the neck, a patient’s chance of survival is cut by half. However, it’s often unclear through imaging and physical assessment if oral cancer has spread, leaving surgeons struggling with whether to preemptively remove lymph nodes–an invasive procedure termed prophylactic neck dissection–during surgery to remove the oral cancer. While most oral cancer surgeries include a prophylactic neck dissection, research shows that up to 70 percent are unnecessary.

“Clinicians and researchers are keen to define a biomarker that accurately predicts metastasis,” said Aditi Bhattacharya, PhD, an assistant professor in the Department of Oral and Maxillofacial Surgery at NYU College of Dentistry, an investigator at NYU Bluestone Center for Clinical Research, and the study’s lead author. “Given that patients with metastatic oral cancer experience more pain, we thought that a patient’s level of pain might help predict metastasis. A surgeon could then use this knowledge to only remove lymph nodes in patients with cancers that are most likely to metastasize.”

In their study in Scientific Reports, the researchers first documented the pain experienced by 72 oral cancer patients before surgery, using an oral cancer pain questionnaire developed by the investigators. While most patients reported some pain, those who suffered with the most pain were more likely to have cancer that spread to lymph nodes in the neck. This observation suggests that patients with less pain are at low risk of metastasis, and will rarely benefit from a neck dissection.

To begin to understand why metastatic cancers are more painful, the investigators looked for differences in gene expression between metastatic cancers from patients with high levels of pain compared to non-metastatic cancers from patients not experiencing pain. Cancer pain is attributed to the release of mediators from cancers that sensitize nerves near the cancer. Forty genes were identified that were more highly expressed in painful metastatic cancers, suggesting that they promote metastasis and mediate cancer pain. Many of these genes are found in exosomes, small vesicles that break away from a cell and can be taken up by other cells–revealing a potential mechanism for how cancers communicate with nerves.

“I have been investigating the underlying cause of oral cancer pain for two decades. This is the first time that we have demonstrated a correlation between a patient’s pain and the clinical behavior of the cancer,” said Schmidt, who is also the director of the NYU Bluestone Center for Clinical Research and professor in the Department of Oral and Maxillofacial Surgery at NYU College of Dentistry.

Next, the team undertook laboratory experiments to study exosomes found in the extracellular fluid of oral cancer cells grown in the lab. When this extracellular fluid was injected into animal models, it produced pain, but when the cancer-derived exosomes in the fluid were removed, it did not cause pain. This suggests that exosomes from cancer may be responsible for oral cancer pain.

Now, with a deeper understanding of why metastatic oral cancers are painful, the researchers point to several potential clinical applications for their research, including a biomarker for oral cancer metastasis to help with surgical decision making and future testing options.

“While we need to undertake a follow-up study, our current data reveal that a patient’s pain intensity score works as well as the current method–depth of invasion, or how deeply a tumor has invaded nearby tissue–as an index to predict metastasis,” said Bhattacharya.

“The identified genes are targets for therapy aimed at stopping pain and cancer. In addition, exosomes shed from cancers can be detected in saliva, blood, and urine, offering the potential for an objective molecular test to diagnose risk of metastasis,” said Donna Albertson, PhD, professor in the Department of Oral and Maxillofacial Surgery at NYU College of Dentistry, an investigator at NYU Bluestone Center for Clinical Research, and the study’s corresponding author.

References: Bhattacharya, A., Janal, M.N., Veeramachaneni, R. et al. Oncogenes overexpressed in metastatic oral cancers from patients with pain: potential pain mediators released in exosomes. Sci Rep 10, 14724 (2020). https://doi.org/10.1038/s41598-020-71298-y

Provided by New York University

Mammals Share Gene Pathways That Allow Zebrafish To Grow New Eyes (Evolution)

Study may advance genetic therapies for blindness and other injuries to the central nervous system.

Working with fish, birds and mice, Johns Hopkins Medicine researchers report new evidence that some animals’ natural capacity to regrow neurons is not missing, but is instead inactivated in mammals. Specifically, the researchers found that some genetic pathways that allow many fish and other cold-blooded animals to repair specialized eye neurons after injury remain present in mammals as well, but are turned off, blocking regeneration and healing.

A description of the study, published online by the journal Science on Oct. 1 (science.sciencemag.org/lookup/doi/10.1126/science.abb8598), offers a better understanding of how genes that control regeneration are conserved across species, as well as how they function. This may help scientists develop ways to grow cells that are lost due to hereditary blindness and other neurodegenerative diseases.

“Our research overall indicates that the potential for regeneration is there in mammals, including humans, but some evolutionary pressure has turned it off,” says Seth Blackshaw, Ph.D., professor of neuroscience at the Johns Hopkins University School of Medicine. “In fact, regeneration seems to be the default status, and the loss of that ability happened at multiple points on the evolutionary tree,” he says.

For the study, Blackshaw’s team focused on supportive cells in the back of the eye. In zebrafish, a standard laboratory model whose genome has been well defined, these cells, known as Müller glia, respond and repair the light-sensitive retina by growing new cells in the central nervous system called neurons. In addition to regrowing eye tissue, zebrafish’s regenerative abilities extend to other body parts, including fins, tails and some internal organs.

The retina is a good testing ground for mapping genetic activity, explains Blackshaw, because it contains structures common to other cells in the nervous system. In previous studies, moreover, scientists have found that the genetic networks in the retina are well conserved across species, so comparisons among fish, birds, mice and even humans are possible.

For the new experiments, the Johns Hopkins researchers created retinal injuries in zebrafish, chickens and mice. Then they used high-powered microscopes and a previously developed gene mapping tool to observe how the supportive Müller glia cells responded.

Blackshaw said the team was surprised to find, immediately after the injury, that the cells in each of the three species behaved the same way: They entered an “active state” characterized by the activation of specific genes, some of which control inflammation.

This active state, says Blackshaw, primarily helps to contain the injury and send signals to immune system cells to combat foreign invaders such as bacteria, or to clean up broken tissue.

Beyond that step, however, the species’ responses diverged.

In zebrafish, active Müller glia began turning on a network of transcription factors that control which genes are ‘on’ and ‘off.’ In the current experiment, the NFI transcription factors activated genes that are linked to cell maturity, sending the Müller glia cells back in developmental time to a more primitive state, which then allows them to develop into many different cell types. The Müller glia then “differentiated” into new cells to replace the ones lost to injury.

In contrast, the research team saw that chickens with damaged retinas activate only some of the transcription factor ‘gene control switches’ that are turned on in zebrafish. Thus, chickens have much less capability to create new Müller glia and other neurons in the eye following injury.

Finally, the researchers looked at the injury response in mice. Mice share the vast majority of their DNA with humans, and their eyes are similar to human eyes. The researchers found that injured Müller glia in mice remained in the first “active” state for several days, much longer than the eight to 12 hours that zebrafish are in this state, and yet never acquired the ability to make new neurons.

Müller glia in all three species also express high levels of nuclear factor I (NFI) transcription factors, but rapidly turn them off following injury. In mice, however, the NFI genes are turned back on soon thereafter, and actively block the Müller glia from generating neurons.

The researchers found, to their surprise, they say, that the same genes that allowed the zebrafish cells to regenerate were “primed and ready to go” in the mouse eye, but that the “on” transcription factor was never activated. Instead, the NFI factors actively block the cells’ regenerative potential.

Blackshaw suspects that animals with a higher potential to develop disease in brain and other neurological tissue may have lost this capability over evolutionary time to help protect and stabilize other brain cells. “For example, we know that certain viruses, bacteria and even parasites can infect the brain. It could be disastrous if infected brain cells were allowed to grow and spread the infection through the nervous system,” says Blackshaw.

Now equipped with a more detailed map of the cellular response to neuronal injury and regrowth, scientists may be able to find a way to activate the regenerative capabilities hidden in human DNA, Blackshaw says.

References: Thanh Hoang, Jie Wang, Patrick Boyd, Fang Wang, Clayton Santiago, Lizhi Jiang, Sooyeon Yoo, Manuela Lahne, Levi J. Todd, Meng Jia, Cristian Saez, Casey Keuthan, Isabella Palazzo, Natalie Squires, Warren A. Campbell, Fatemeh Rajaii, Trisha Parayil, Vickie Trinh, Dong Won Kim, Guohua Wang, Leah J. Campbell, John Ash, Andy J. Fischer, David R. Hyde, Jiang Qian, Seth Blackshaw, “Gene regulatory networks controlling vertebrate retinal regeneration”, Science, Oct 2020: eabb8598 DOI: 10.1126/science.abb8598

Provided by Hopkins Medicine

Paleontologists Identify New Species Of Mosasaur (Paleontology)

A new species of an ancient marine reptile evolved to strike terror into the hearts of the normally safe, fast-swimming fish has been identified by a team of University of Alberta researchers, shedding light on what it took to survive in highly competitive ecosystems.

Artist’s rendering of Gavialimimus almaghribensis, a newly discovered species of mosasaur that ruled the seas of what is now Morocco some 72 to 66 million years ago. CREDIT: Tatsuya Shinmura

Gavialimimus almaghribensis, a new type of mosasaur, was catalogued and named by an international research team led by master’s student Catie Strong, who performed the research a year ago as part of an undergrad honours thesis guided by vertebrate paleontologist Michael Caldwell, professor in the Faculty of Science, along with collaborators from the University of Cincinnati and Flinders University.

More than a dozen types of mosasaur–which can reach 17 metres in length and resemble an overgrown komodo dragon–ruled over the marine environment in what is now Morocco at the tail end of the Late Cretaceous period between 72 and 66 million years ago.

What differentiates Strong’s version, however, is that it features a long, narrow snout and interlocking teeth–similar to the crocodilian gharials, a relative of crocodiles and alligators.

Strong said this discovery adds a layer of clarity to a diverse picture seemingly overcrowded with mega-predators all competing for food, space and resources.

“Its long snout reflects that this mosasaur was likely adapted to a specific form of predation, or niche partitioning, within this larger ecosystem.”

Strong explained there is evidence that each species of the giant marine lizard shows adaptations for different prey items or styles of predation.

“For some species, these adaptations can be very prominent, such as the extremely long snout and the interlocking teeth in Gavialimimus, which we hypothesized as helping it to catch rapidly moving prey,” she said.

She added another distinctive species would be Globidens simplex–described last year by the Caldwell lab–which has stout, globular teeth adapted for crushing hard prey like shelled animals.

“Not all of the adaptations in these dozen or so species are this dramatic, and in some cases there may have been some overlap in prey items, but overall there is evidence that there’s been diversification of these species into different niches,” Strong noted.

Alternatively, the main contrasting hypothesis would be a scenario of more direct competition among species. Strong said given the anatomical differences among these mosasaurs, though, the idea of niche partitioning seems more consistent with the anatomy of these various species.

“This does help give another dimension to that diversity and shows how all of these animals living at the same time in the same place were able to branch off and take their own paths through evolution to be able to coexist like that,” she said.

The remains of the G. almaghribensis included a metre-long skull and some isolated bones. There was nothing to explain the cause of death of the specimen, which was uncovered in a phosphate mine in Morocco that is rich in fossils.

“Morocco is an incredibly good place to find fossils, especially in these phosphate mines,” Strong said. “Those phosphates themselves reflect sediments that would have been deposited in marine environments, so there are a lot of mosasaurs there.”

Provided by University Of Alberta

Molecular Swarm Rearranges Surface Structures Atom By Atom (Nanotechnology / Engineering)

The surface of metals plays a key role in many technologically relevant areas, such as catalysis, sensor technology and battery research. For example, the large-scale production of many chemical compounds takes place on metal surfaces, whose atomic structure determines if and how molecules react with one another. At the same time, the surface structure of a metal influences its electronic properties. This is particularly important for the efficiency of electronic components in batteries. Researchers worldwide are therefore working intensively on developing new kinds of methods to tailor the structure of metal surfaces at the atomic level.

Much like a zipper, carbene molecules cooperate on a gold surface to join two rows of atoms into one row, resulting – step by step – in a new surface structure. ©Saeed Amirjalayer

A team of researchers at the University of Münster, consisting of physicists and chemists and led by Dr. Saeed Amirjalayer, has now developed a molecular tool which makes it possible, at the atomic level, to change the structure of a metal surface. Using computer simulations, it was possible to predict that the restructuring of the surface by individual molecules – so-called N-heterocyclic carbenes – takes place similar to a zipper. During the process, at least two carbene molecules cooperate to rearrange the structure of the surface atom by atom. The researchers could experimentally confirm, as part of the study, this “zipper-type” mechanism in which the carbene molecules work together on the gold surface to join two rows of gold atoms into one row. The results of the work have been published in the journal “Angewandte Chemie International Edition”.

In earlier studies the researchers from Münster had shown the high stability and mobility of carbene molecules at the gold surface. However, no specific change of the surface structure induced by the molecules could previously be demonstrated. In their latest study, the researchers proved for the first time that the structure of a gold surface is modified very precisely as a result of cooperation between the carbene molecules. “The carbene molecules behave like a molecular swarm – in other words, they work together as a group to change the long-range structure of the surface,” Saeed Amirjalayer explains. “Based on the ‘zipper’ principle, the surface atoms are systematically rearranged, and, after this process, the molecules can be removed from the surface.”

The new method makes it possible to develop new materials with specific chemical and physical properties – entirely without macroscopic tools. “In industrial applications often macroscopic tools, such presses or rollers, are used,” Amirjalayer continues. “In biology, these tasks are undertaken by certain molecules. Our work shows a promising class of synthesized molecules which uses a similar approach to modify the surface.” The team of researchers hopes that their method will be used in future to develop for examples new types of electrode or to optimize chemical reactions on surfaces.

References: Amirjalayer, S., Bakker, A., Freitag, M., Glorius, F. and Fuchs, H. (2020), Cooperation of N‐Heterocyclic Carbenes on a Gold Surface. Angew. Chem. Int. Ed.. doi:10.1002/anie.202010634 link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202010634

Provided by University Of Munster

Green Suburbs Can Be More Harmful To Urban Residents Than City Centers, Say Soil Scientists From RUDN University (Nature)

A team of soil scientists from RUDN University confirmed that traditional approaches to urban soil pollution monitoring ignore actual risks for urban residents because they don’t take into consideration the barrier function of the soil. The team used Moscow as an example to show that not only polluted downtown districts but also recreational parks and forest zones can pose a threat to people. This is due to the fact that the barrier functions of the soil are weaker in green suburbs, making it unable to withstand even the slightest pollution. The results of the study were published in the Journal of Environmental Quality.

A team of soil scientists from RUDN University confirmed that traditional approaches to urban soil pollution monitoring ignore actual risks for urban residents because they don’t take into consideration the barrier function of the soil. The team used Moscow as an example to show that not only polluted downtown districts but also recreational parks and forest zones can pose a threat to people. This is due to the fact that the barrier functions of the soil are weaker in green suburbs, making it unable to withstand even the slightest pollution. ©RUDN University

Industrial soil pollution with heavy metals poses a threat to human health. From the soil, harmful substances get into the water, dust, and plants. The intensity of these processes depends on the properties of the soil, namely its organic content, acidity, and texture. For example, clay and loam soils act as a geochemical barrier: they retain harmful substances and don’t let them spread. However, traditional approaches to ecological monitoring overlook this barrier role and assess risks based only on the concentration of contaminating agents. Using these methods, one can miss potentially harmful zones or overestimate the danger. A team of soil scientists from RUDN University developed the first map of Moscow that takes into account not only the level of heavy metal pollution but also the barrier function of the soils.

The experiment covered nine administrative districts of Moscow with a total area of over 1,000 km². The main sources of contamination across this territory were industrial facilities and automobiles. The researchers took soil samples from 224 points in public spaces, residential areas, and industrial zones. The samples were dried and ground to measure their soil texture, organic content, and acidity. Based on these parameters, the team calculated the ability of the samples to contain pollutants. Then, using spectral analysis, the researchers measured the concentrations of heavy metals: nickel, cadmium, manganese, lead, copper, zinc, arsenic, and mercury. After that, individual concentration and containment maps were developed and integrated into one general map.

In over 30% of the samples, heavy metal concentrations exceeded the norms of the Russian Agency for Health and Consumer Rights (Rospotrebnadzor). For example, the prohibitive amount of copper in 1 kg of soil is 33 to 132 mg (depending on soil type), and of arsenic–from 2 to 10 mg. However, in some cases, these norms were exceeded 2 to 5 times. The most polluted soils were the ones taken from public places downtown. However, loam soil with alkaline acidity that is typical for the center of Moscow has a high barrier activity index, which means it can retain the pollution. At the same time, more sandy and acidic in topsoils have weaker barrier functions, and though the concentration of harmful substances there is lower, they cannot withstand the pollution. The team concluded that in order to effectively assess the ecological situation in the city, one has to take into account both the level of pollution and the ability of the soil to stop it. Traditional monitoring approaches based solely on concentration levels do not give an adequate risk profile.

“We developed pollution level maps and the maps of soils as geochemical barriers, and they turned out not to match each other. In some cases, the ability of the soils to bind down heavy metals compensates for high pollution levels. On the other hand, in some green zones topsoils are unable to contain even the smallest amounts of pollutants. Our results show how important it is to see the bigger picture and take both factors into consideration,” said Olga Romzaykina, a researcher at the Research Laboratory “Smart Technologies for Sustainable Urban Development under Global Change”, RUDN University.

References: Romzaykina, ON, Vasenev, VI, Paltseva, A, Kuzyakov, YV, Neaman, A, Dovletyarova, EA. Assessing and mapping urban soils as geochemical barriers for contamination by heavy metal(loid)s in Moscow megapolis. J. Environ. Qual. 2020; 1– 16. https://doi.org/10.1002/jeq2.20142 link: https://acsess.onlinelibrary.wiley.com/doi/10.1002/jeq2.20142

Provided by RUDN university

Beat The Heat: Novel Passive Cooling Device For Surfaces And Enclosed Spaces (Engineering)

Scientists engineer the first passive radiative device that absorbs heat from the inside of an enclosure and emits it on the outside.

If you have ever stepped into a car parked under the sun, you would be familiar with how hot it can get on the inside. This occurs because although sunlight can pass through the transparent windows, the thermal radiation re-emitted by the interior cannot, thereby creating a “greenhouse effect” and heating the inside of the car to temperatures as high as 82°C. Elderly people and children are at a particularly high risk of suffering heatstroke or hyperthermia at such temperatures.

Passive colling device. The bottom layer of the Janus emitter absorbs the heat inside the vehicle and emits it through the top layer to the atmosphere (indicated in blue), causing a temperature drop. The right image shows an experimental model that simulates a vehicle. CREDIT: Young Min Song/GIST

This heat from a parked vehicle can be released by either spending energy in active cooling, which is not sustainable, or opening a window, which is not ideal on rainy days or when driving on a highway. Fortunately, scientists from Gwangju Institute of Science and Technology (GIST), Korea, have developed a new type of passive cooling technology to solve this issue.

In a new study, published in Science Advances, they present a device called “Janus emitter,” or JET. Named after the two-faced Greek god Janus, the JET comprises a stack of patterned quartz, silver, and polydimethylsiloxane thin layers. Each face of the JET has unique properties for passively cooling enclosed spaces. The bottom side absorbs a broad spectrum of thermal radiation from inside the enclosure and, through a quantum phenomenon called “spoof surface plasmon polaritons,” re-emits this energy to the atmosphere on the top side in a selective frequency range that maximizes emissivity. Prof Young Ming Song, who led this study, explains, “The ‘Janus’ thermal radiation characteristics of the JET allow it to function as a heat channel that efficiently draws heat from the enclosure and sends it outside.”

The JET requires no electricity at all and no conscious effort from the user, which makes it a sustainable way of keeping the temperature of stationary vehicles, building interiors, and solar cells low. Excited about the results, Dr Song concludes, “Our work is the first to address passive radiative cooling for enclosed spaces, and we hope it creates a ripple effect that bolsters research in this field.”

Indeed, as this novel technology takes off, staying cool doesn’t have to be so hard anymore!

References: Se-Yeon Heo, Gil Ju Lee, Do Hyeon Kim, Yeong Jae Kim, Satoshi Ishii, Min Seok Kim, Tae Joon Seok, Bong Jae Lee, Heon Lee, Young Min Song, “A Janus emitter for passive heat release from enclosures”, Science Advances 04 Sep 2020: Vol. 6, no. 36, eabb1906
DOI: 10.1126/sciadv.abb1906 link: https://advances.sciencemag.org/content/6/36/eabb1906

Provided by GIST

Looking For Pieces Of Venus? Try The Moon (Planetary Science)

A growing body of research suggests the planet Venus may have had an Earth-like environment billions of years ago, with water and a thin atmosphere.

Yet testing such theories is difficult without geological samples to examine. The solution, according to Yale astronomers Samuel Cabot and Gregory Laughlin, may be closer than anyone realized.

Cabot and Laughlin say pieces of Venus — perhaps billions of them — are likely to have crashed on the moon. A new study explaining the theory has been accepted by the Planetary Science Journal.

The researchers said asteroids and comets slamming into Venus may have dislodged as many as 10 billion rocks and sent them into an orbit that intersected with Earth and Earth’s moon. “Some of these rocks will eventually land on the moon as Venusian meteorites,” said Cabot, a Yale graduate student and lead author of the study.

Cabot said catastrophic impacts such as these only happen every hundred million years or so — and occurred more frequently billions of years ago.

“The moon offers safe keeping for these ancient rocks,” Cabot said. “Anything from Venus that landed on Earth is probably buried very deep, due to geological activity. These rocks would be much better preserved on the moon.”

Many scientists believe that Venus might have had an Earth-like atmosphere as recently as 700 million years ago. After that, Venus experienced a runaway greenhouse effect and developed its current climate. The Venusian atmosphere is so thick today that no rocks could possibly escape after an impact with an asteroid or comet, Cabot said.

Laughlin and Cabot cited two factors supporting their theory. The first is that asteroids hitting Venus are usually going faster than those that hit Earth, launching even more material. The second is that a huge fraction of the ejected material from Venus would have come close to Earth and the moon.

“There is a commensurability between the orbits of Venus and Earth that provides a ready route for rocks blasted off Venus to travel to Earth’s vicinity,” said Laughlin, who is professor of astronomy and astrophysics at Yale. “The moon’s gravity then aids in sweeping up some of these Venusian arrivals.”

Upcoming missions to the moon could give Cabot and Laughlin their answer soon. The researchers said NASA’s Artemis program is the perfect opportunity to collect and analyze unprecedented amounts of lunar soil.

Laughlin said there are several standard chemical analyses that can pinpoint the origin of moon rocks, including any that came from Venus. Different ratios of specific elements and isotopes offer a kind of fingerprint for each planet in the solar system.

“An ancient fragment of Venus would contain a wealth of information,” Laughlin said. “Venus’ history is closely tied to important topics in planetary science, including the past influx of asteroids and comets, atmospheric histories of the inner planets, and the abundance of liquid water.”

Provided by Yale University