Hexbyte Glen Cove Three out of four turtle populations risk cadmium contamination thumbnail

Hexbyte Glen Cove Three out of four turtle populations risk cadmium contamination

Hexbyte Glen Cove

Lead researcher & PhD candidate Gulsah Dogruer, Australian Rivers Institute. Credit: Griffith University

Three out of four Queensland green turtle populations risk harmful effects from cadmium found a Griffith University-led study using a new tool to determine chemical exposure limits for marine animals.

In collaboration with Utrecht University (Netherlands), Goethe University Frankfurt (Germany) and the University of Queensland, the researchers developed a virtual turtle model to simulate cadmium uptake and its effects over a turtles’ lifetime. The model was used to reveal at what concentration cadmium in their primary food source, seagrass, is potentially toxic.

“Marine animals are exposed to an array of toxic chemicals entering the oceans,” said lead researcher and Ph.D. candidate Gulsah Dogruer from the Australian Rivers Institute.

“Yet policy makers are basically in the dark about the limits these animals can endure before health effects threaten their survival.

“We developed a framework that sheds some light on this issue for policy makers. By defining the chemical exposure limit for a particular marine animal before there is , we can help policy makers identify potentially toxic areas.”

When applied to cadmium in , the researchers revealed a concerning 72% of the Great Barrier Reef’s green turtle populations were at risk from cadmium contamination.

“Our results show that a green turtle population foraging on seagrass with more than 0.1 milligram of cadmium for every kilogram of seagrass, is exposed to potential health risks,” said co-author and supervisor Dr. Jason van de Merwe, a marine ecologist and eco-toxicologist at the Australian Rivers Institute.

“As seagrass is green turtles’ primary source of food, this is a real concern, but knowing this threshold level of cadmium is crucial to identify potential exposure sites.”

The virtual turtle model consisting of seven body compartments connected by the circulating blood flow (red arrow). The liver and kidney represent the elimination and detoxification routes (green arrow). The blue arrow represents the exposure route. Credit: Griffith University

To discover the cadmium threshold in green turtles, the researchers used a generic three-step framework that can be adapted to other marine species and other chemicals.

The framework involved firstly developing a green turtle and cadmium-specific model to predict how much cadmium the turtles are likely to accumulate over their lifetime under various environmental conditions.

“The model we developed used the physiology of the turtles and the chemical properties of cadmium to simulate its absorption, metabolism, excretion, and distribution in the turtles’ liver, kidney, muscle, fat, brain, scute, and ‘rest of the body’,” Ms Dogruer said.

“The second step was to link these contaminant concentrations in the turtles to toxic effects seen in laboratory-based studies and in free-ranging turtles.

The researchers ran the model in reverse, using the cadmium concentration that is toxic in turtles’ body, to determine the amount of cadmium in seagrass above which are likely to have a toxic response (0.1 milligram of cadmium for every kilogram of seagrass).

The researchers lastly compared their results to real-world cadmium exposure conditions for green turtle populations globally.

“Three out of the four globally distinct green turtle populations assessed in Australia, Japan and Brazil are exposed to levels above the threshold seagrass limits we reported,” Dr. van de Merwe said.

“Our framework for determining chemical exposure limits will help managers of conservation sites better understand and minimize the risk to and hopefully begin to turn the tide for green turtle populations worldwide,” Ms Dogruer said.

Three out of four turtle populations risk cadmium contamination (2021, August 20)
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Hexbyte Glen Cove Galaxy cluster Abell 3158 inspected in X-rays thumbnail

Hexbyte Glen Cove Galaxy cluster Abell 3158 inspected in X-rays

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Galaxy density map with members of Abell 3158. Credit: Whelan et al., 2021.

Astronomers from the University of Bonn, Germany and elsewhere have used the eROSITA telescope onboard the Spektrum-Roentgen-Gamma (SRG) mission to perform X-rays observations of a nearby galaxy cluster known as Abell 3158. Results of this observational campaign, published June 28 on arXiv.org, offer more clues on the properties of this giant structure.

Galaxy clusters contain up to thousands of galaxies bound together by gravity. They are the largest known gravitationally bound structures in the universe, and could serve as excellent laboratories for studying galaxy evolution and cosmology.

At a redshift of 0.059 and characteristic radius of approximately 23.95 arcminutes, Abell 3158 (or A3158 for short) is a quite extended nearby galaxy cluster. Given its relative proximity, Abell 3158 is a good place to examine the faint outskirts where physical and enrichment processes are taking place, such as minor mergers or infall of gas clumps.

A team of astronomers led by Béibhinn Whelan of the University of Bonn, has employed eROSITA to investigate the peripheral regions of Abell 3158 in order to shed more light on the properties of this object. The study was complemented by data from ESA’s XMM-Newton satellite.

“We determined 1d temperature, abundance and normalisation profiles from both eROSITA and XMM-Newton data, as well as 2D maps of temperature and metal abundance distribution from eROSITA data,” the researchers wrote in the paper.

The overall temperature of Abell 3158 was measured to be about 4.725 keV. The astronomers noted that temperature, abundance and normalisation profiles of eROSITA are consistent with previous studies of this cluster.

The eROSITA data provided tighter constraints on the metal abundance of Abell 3158 out to large radii. According to the paper, the normalisation profile shows that the values obtained from the XMM-Newton observation are slightly higher than those from eROSITA.

The study found that the morphology and surface brightness profile of Abell 3158 seem to be regular. However, the 2D temperature map of Abell 3158 shows that the cluster does not have a cool core, what is unusual for a cluster with such a surface brightness profile.

Furthermore, based on the spectroscopic redshifts of 365 members of Abell 3158, the velocity dispersion of the cluster member was measured to be some 1,058 km/s. The total mass of the cluster was calculated to be 1.38 quadrillion .

The research also identified an extension of gas some 2.2 million light years in the west direction from the center of Abell 3158. This finding suggests that the cluster is not relaxed but is undergoing merger activity.

“There exists an extension of gas ∼10 arcmin (∼865 kpc) to the West of the cluster centre, observed in the bottom image in the logarithmic scale. We present this extension of gas as a new finding. The irregularities between the different scales would suggest that there may be a sloshing effect occurring in the cluster further supporting the claim that the is undergoing merger activity,” the authors of the paper concluded.

More information:
X-Ray Studies of the Abell 3158 Galaxy Cluster with eROSITA, arXiv:2106.14545 [astro-ph.CO] arxiv.org/abs/2106.14545

© 2021 Science X Network

Galaxy cluster Abell 3158 inspected in X-rays (2021, July 6)
retrieved 7 July 2021
from https://phys.o

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Hexbyte Glen Cove A new material made from carbon nanotubes can generate electricity by scavenging energy from its environment thumbnail

Hexbyte Glen Cove A new material made from carbon nanotubes can generate electricity by scavenging energy from its environment

Hexbyte Glen Cove

Credit: Pixabay/CC0 Public Domain

MIT engineers have discovered a new way of generating electricity using tiny carbon particles that can create a current simply by interacting with liquid surrounding them.

The liquid, an , draws electrons out of the particles, generating a current that could be used to drive or to power micro- or nanoscale robots, the researchers say.

“This mechanism is new, and this way of generating is completely new,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. “This technology is intriguing because all you have to do is flow a solvent through a bed of these particles. This allows you to do electrochemistry, but with no wires.”

In a new study describing this phenomenon, the researchers showed that they could use this to drive a reaction known as alcohol oxidation—an organic chemical reaction that is important in the chemical industry.

Strano is the senior author of the paper, which appears today in Nature Communications. The lead authors of the study are MIT graduate student Albert Tianxiang Liu and former MIT researcher Yuichiro Kunai. Other authors include former graduate student Anton Cottrill, postdocs Amir Kaplan and Hyunah Kim, graduate student Ge Zhang, and recent MIT graduates Rafid Mollah and Yannick Eatmon.

Unique properties

The new discovery grew out of Strano’s research on nanotubes—hollow tubes made of a lattice of carbon atoms, which have unique electrical properties. In 2010, Strano demonstrated, for the first time, that carbon nanotubes can generate “thermopower waves.” When a is coated with layer of fuel, moving pulses of heat, or thermopower waves, travel along the tube, creating an electrical current.

That work led Strano and his students to uncover a related feature of carbon nanotubes. They found that when part of a nanotube is coated with a Teflon-like polymer, it creates an asymmetry that makes it possible for electrons to flow from the coated to the uncoated part of the tube, generating an . Those electrons can be drawn out by submerging the particles in a solvent that is hungry for electrons.

To harness this special capability, the researchers created electricity-generating particles by grinding up carbon nanotubes and forming them into a sheet of paper-like material. One side of each sheet was coated with a Teflon-like polymer, and the researchers then cut out , which can be any shape or size. For this study, they made particles that were 250 microns by 250 microns.

When these particles are submerged in an organic solvent such as acetonitrile, the solvent adheres to the uncoated surface of the particles and begins pulling electrons out of them.

“The solvent takes electrons away, and the system tries to equilibrate by moving electrons,” Strano says. “There’s no sophisticated battery chemistry inside. It’s just a particle and you put it into solvent and it starts generating an electric field.”

Particle power

The current version of the particles can generate about 0.7 volts of electricity per particle. In this study, the researchers also showed that they can form arrays of hundreds of particles in a small test tube. This “packed bed” reactor generates enough energy to power a chemical reaction called an alcohol oxidation, in which an alcohol is converted to an aldehyde or a ketone. Usually, this reaction is not performed using electrochemistry because it would require too much external current.

“Because the packed bed reactor is compact, it has more flexibility in terms of applications than a large electrochemical reactor,” Zhang says. “The particles can be made very small, and they don’t require any external wires in order to drive the electrochemical reaction.”

In future work, Strano hopes to use this kind of energy generation to build polymers using only carbon dioxide as a starting material. In a related project, he has already created polymers that can regenerate themselves using carbon dioxide as a building material, in a process powered by solar energy. This work is inspired by carbon fixation, the set of chemical reactions that plants use to build sugars from carbon dioxide, using energy from the sun.

In the longer term, this approach could also be used to power micro- or nanoscale robots. Strano’s lab has already begun building robots at that scale, which could one day be used as diagnostic or environmental sensors. The idea of being able to scavenge energy from the environment to power these kinds of robots is appealing, he says.

“It means you don’t have to put the energy storage on board,” he says. “What we like about this mechanism is that you can take the energy, at least in part, from the environment.”

More information:
Albert Tianxiang Liu et al, Solvent-induced electrochemistry at an electrically asymmetric carbon Janus particle, Nature Communications (2021). DOI: 10.1038/s41467-021-23038-7

A new material made from carbon nanotubes can generate electricity by

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