Why North Atlantic Tuna Is Less Toxic ?

In a piece of welcome news for seafood lovers, a Stony Brook-led research team has found declining levels of mercury in bluefin tuna caught in the North Atlantic over the past decadeMercury is a neurotoxin harmful to humans, and tuna provide more mercury to humans than any other source.

A study led by Stony Brook University’s School of Marine and Atmospheric Sciences (SoMAS) and published in Environmental Science & Technology provides a new data set, the largest of its kind, of mercury concentrations in Atlantic bluefin tuna. The data demonstrate that, while tissue concentrations were higher than in most other fish species, there has been a consistent decline in mercury concentrations in these tuna over time, regardless of age of the fish.

blue-sea

KEY FINDINGS:

The researchers measured mercury concentrations from the tissue of 1,292 bluefin tuna caught between 2004 and 2012

  • Over the eight-year period, mercury levels in the fish fell 19 percent.
  • Mercury concentrations were generally high, and were highest in the largest, oldest fish; no differences were noted between males and females.
  • Mercury in the air over the North Atlantic fell 20 percent from 2001 to 2009.
  • Global levels of mercury emissions have fallen 2.8 percent a year from 1990 to 2007.

The rate of decline parallels the declines – over the same time period — of mercury emissions, mercury levels in North Atlantic air, and mercury concentrations in North Atlantic seawater. Authors of the study include Stony Brook’s Cheng-Shiuan Lee, a Ph.D student in chemical/biological oceanography, and Nicholas S. Fisher, Distinguished Professor & Director, Consortium for Inter-Disciplinary Environmental Research at SoMAS.

According Fisher, the finding appears to indicate that changes in mercury levels in fish tissue respond in real time to changes in mercury loadings into the ocean. The study suggests that mercury levels may be improving as a result of declining coal use, reducing emissions that drift over the Atlantic.

Source: http://www.stonybrook.edu/

How To Charge A Phone Battery In 30 Seconds

If you add quantum dotsnanocrystals 10,000 times smaller than the width of a human hair – to a smartphone battery it will charge in 30 seconds, but the effect only lasts for a few recharge cycles.

However, a group of researchers at Vanderbilt University report in  of the journal ACS Nano that they have found a way to overcome this problem: Making the quantum dots out of iron pyrite, commonly known as fool’s gold, can produce batteries that charge quickly and work for dozens of cycles.

The research team headed by Assistant Professor of Mechanical Engineering Cary Pint and led by graduate student Anna Douglas became interested in iron pyrite because it is one of the most abundant materials in the earth’s surface. It is produced in raw form as a byproduct of coal production and is so cheap that it is used in lithium batteries that are bought in the store and thrown away after a single use.

Despite all their promise, researchers have had trouble getting nanoparticles to improve battery performance.

nanocrystals

Researchers have demonstrated that nanoscale materials can significantly improve batteries, but there is a limit,” Pint said. “When the particles get very small, generally meaning below 10 nanometers (40 to 50 atoms wide), the nanoparticles begin to chemically react with the electrolytes and so can only charge and discharge a few times. So this size regime is forbidden In commercial lithium-ion batteries.”

Source: http://news.vanderbilt.edu/

How To Trap Greenhouse Gases

Emissions from the combustion of fossil fuels like coal, petroleum and natural gas tend to collect within Earth’s atmosphere as “greenhouse gases” that are blamed for escalating global warming.

So researchers around the globe are on a quest for materials capable of capturing and storing greenhouse gases. This shared goal led researchers at Technische Universität Darmstadt in Germany and the Indian Institute of Technology Kanpur to team up to explore the feasibility of vertically aligned carbon nanotubes (VACNTs) to trap and store two greenhouse gases in particular: carbon dioxide (CO2) and sulfur dioxide (SO2). As the team reports in The Journal of Chemical Physics, from AIP Publishing, they discovered that gas adsorption in VACNTs can be influenced by adjusting the morphological parameters of the carbon nanotube thickness, the distance between nanotubes, and their height.

Carbon nanotubes against greenhouse gases
Snapshots of CO2 adsorption in double-walled carbon nanotube arrays (with an inner tube diameter of 2r=3 nanometers and various inter-tube distance at T=303 K and p=1 bar)

 

These parameters are fundamental for ‘tuning’ the hierarchical pore structure of the VACNTs,” explained Mahshid Rahimi and Deepu Babu, the paper’s lead authors and doctoral students in theoretical physical chemistry and inorganic chemistry at the Technische Universität Darmstadt. “This hierarchy effect is a crucial factor for getting high-adsorption capacities as well as mass transport into the nanostructure. Surprisingly, from theory and by experiment, we found that the distance between nanotubes plays a much larger role in gas adsorption than the tube diameter does.

Source: https://www.aip.org/

How To Improve Efficency Of Power Plants

Most of the world’s electricity-producing power plants — whether powered by coal, natural gas, or nuclear fission — make electricity by generating steam that turns a turbine. That steam then is condensed back to water, and the cycle begins again.
But the condensers that collect the steam are quite inefficient, and improving them could make a big difference in overall power plant efficiency.
Now, a team of researchers at MIT has developed a way of coating these condenser surfaces with a layer of graphene, just one atom thick, and found that this can improve the rate of heat transfer by a factor of four — and potentially even more than that, with further work. And unlike polymer coatings, the graphene coatings have proven to be highly durable in laboratory tests.
The findings are reported in the journal Nano Letters by MIT graduate student Daniel Preston, professors Evelyn Wang and Jing Kong, and two others. The improvement in condenser heat transfer, which is just one step in the power-production cycle, could lead to an overall improvement in power plant efficiency of 2 to 3 percent based on figures from the Electric Power Research Institute, Preston says — enough to make a significant dent in global carbon emissions, since such plants represent the vast majority of the world’s electricity generation. “That translates into millions of dollars per power plant per year,” he explains.
MIT-Graphene-Coating
An uncoated copper condenser tube (top left) is shown next to a similar tube coated with graphene (top right). When exposed to water vapor at 100 degrees Celsius, the uncoated tube produces an inefficient water film (bottom left), while the coated shows the more desirable dropwise condensation (bottom right)
We thought graphene could be useful,” Preston says, “since we know it is hydrophobic by nature.”
They found that the single-atom-thick coating of graphene did indeed improve heat transfer fourfold compared with surfaces where the condensate forms sheets of water, such as bare metals. Further calculations showed that optimizing temperature differences could boost this improvement to 5 to 7 times. The researchers also showed that after two full weeks under such conditions, there was no measurable degradation in the graphene’s performance.

Source: http://newsoffice.mit.edu/

How To Reduce CO2 Emissions From Power Stations

University of Adelaide – Australia – researchers have developed a new nanomaterial that could help reduce carbon dioxide emissions from coal-fired power stations.
The new nanomaterial, described in the Journal of the American Chemical Society, efficiently separates the greenhouse gas carbon dioxide from nitrogen, the other significant component of the waste gas released by coal-fired power stations. This would allow the carbon dioxide to be separated before being stored, rather than released to the atmosphere.

co2 emisssion
A considerable amount of Australia’s – and the world’s – carbon dioxide emissions come from coal-fired power stations,” says Associate Professor Christopher Sumby, project leader and ARC Future Fellow in the University’s School of Chemistry and Physics.
Removing CO2 from the flue gas mixture is the focus of a lot of research. Most of Australia’s energy generation still comes from coal. Changing to cleaner energies is not that straightforward but, if we can clean up the emissions, we’ve got a great stop-gap technology.

Sourc: http://www.newswise.com/