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Category: energy – Page 161

Squeaky, cloudy or spherical—electron orbitals show where and how electrons move around atomic nuclei and molecules. In modern chemistry and physics, they have proven to be a useful model for quantum mechanical description and prediction of chemical reactions. Only if the orbitals match in space and energy can they be combined—this is what happens when two substances react with each other chemically. In addition, there is another condition that must be met, as researchers at Forschungszentrum Jülich and the University of Graz have now discovered: The course of chemical reactions also appears to be dependent on the orbital distribution in momentum space. The results were published in the journal Nature Communications.

Chemical reactions are ultimately nothing more than the formation and breakdown of electron bonds, which can also be described as orbitals. The so-called molecular orbital theory thus makes it possible to predict the path of chemical reactions. Chemists Kenichi Fukui and Roald Hoffmann received the Nobel Prize in 1981 for greatly simplifying the method, which led to its widespread use and application.

“Usually, the energy and location of electrons are analyzed. However, using the photoemission tomography method, we looked at the momentum distribution of the orbitals,” explains Dr. Serguei Soubatch. Together with his colleagues at the Peter Grünberg Institute (PGI-3) in Jülich and the University of Graz in Austria, he adsorbed various types of molecules on in a series of experiments and mapped the measured momentum in the so-called momentum space.

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Because of their unique physical, photonic, thermal, and electronic capabilities, two-dimensional (2D) nanostructures have exhibited tremendous promise in the domains of bioengineering, sensing, and energy storage.

Study: Two Dimensional Silicene Nanosheets: A New Choice of Electrode Material for High-Performance Supercapacitor. Image Credit: Quardia/Shutterstock.com.

Nonetheless, combining silicon-based nanomaterials into high-performance power storage systems remains a largely undeveloped subject because of the complex manufacturing process. New work published in the journal ACS Applied Materials & Interfaces hope to address this problem by effectively integrating silicene nanosheets into a high-voltage supercapacitor.

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DENVER — During the dog days of summer, it’s important to keep your home cool. But when thousands of Xcel customers in Colorado tried adjusting their thermostats Tuesday, they learned they had no control over the temperatures in their own homes.

Temperatures climbed into the 90s Tuesday, which is why Tony Talarico tried to crank up the air conditioning in his partner’s Arvada home.

“I mean, it was 90 out, and it was right during the peak period,” Talarico said. “It was hot.”

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The most massive star known by astronomers is truly of gargantuan proportions. Dubbed R136a1, this is the most massive and luminous star ever discovered in the cosmos. Additionally, it belongs to the Large Magellanic Cloud and is one of the hottest stars out there, and it is very, very different than our Sun.

Astronomers have obtained the sharpest image ever of star R136a1, the most massive known star in the Universe, with the 8.1-meter Gemini South telescope in Chile, part of the International Gemini Observatory operated by NSF’s NOIRLab. Researchers at NOIRLab, led by Venu Kalari, challenge our understanding of the most massive stars and suggest their mass may be lower than previously believed.

The formation of the biggest stars – those with 100 times the mass of the Sun – is still a mystery to astronomers. Observing these giants, which normally reside within dust-shrouded star clusters, is challenging. A giant star’s fuel reserves are depleted in less than a million years. Compared with our Sun, which has a lifespan of about 10 billion years, ours is less than halfway through. Individual massive stars in clusters are difficult to distinguish due to their densely packed nature, short lifetimes, and vast astronomical distances.

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NASA’s new moon rocket sprang another dangerous fuel leak Saturday, forcing launch controllers to call off their second attempt to send a crew capsule into lunar orbit with test dummies.

The first attempt earlier in the week was also marred by escaping hydrogen, but those leaks were elsewhere on the 322-foot (98-meter) rocket, the most powerful ever built by NASA.

NASA Administrator Bill Nelson said could bump the launch into October.

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Scientists have worked out how to use an infrared laser to charge devices at a distance. The system can deliver up to 400 milliwatts of power up to a distance of 30 meters (100 feet). That amount of power is sufficient to charge small sensors and other tech, and with developments, it could be possible to charge mobile devices too.

The work, published in the journal Optics Express, focused on a method called distributed laser charging. They showed that an infrared laser (whose wavelength can’t harm skin or eyes) was shined through a spherical ball lens towards a device with a photovoltaic receiver of 10 by 10 millimeters (0.4 by 0.4 inches).

The receiver is small enough to be attached to many mobile devices and sensors, and the team showed that it was able to convert 400 milliwatts to 85 milliwatts of electrical power. A small but significant result.

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Thermoelectric devices convert thermal energy into electricity by generating a voltage from the difference in temperature between the hot and cold parts of a device.

To better understand how the conversion process occurs at the atomic scale, researchers used neutrons to study single crystals of tin sulfide and tin selenide. They measured changes that were dependent on temperature.

The measurements revealed a strong correlation between changes in the structure at certain temperatures and the frequency of atomic vibrations (phonons). This relationship affects how the materials conduct heat.

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“We don’t need any energy input, and it bubbles hydrogen like crazy. I’ve never seen anything like it,” said UCSC Professor Scott Oliver, describing a new aluminum-gallium nanoparticle powder that generates H2 when placed in water – even seawater.

Aluminum by itself rapidly oxidizes in water, stripping the O out of H2O and releasing hydrogen as a byproduct. This is a short-lived reaction though, because in most cases the metal quickly attains a microscopically thin coating of aluminum oxide that seals it off and puts an end to the fun.

But chemistry researchers at UC Santa Cruz say they’ve found a cost-effective way to keep the ball rolling. Gallium has long been known to remove the aluminum oxide coating and keep the aluminum in contact with water to continue the reaction, but previous research had found that aluminum-heavy combinations had a limited effect.

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Circa 2016

A radically new form of lithium-oxygen batteries avoids many of the problems that have prevented the uptake of what is, in theory, the ultimate transportation battery. If the work can be scaled up, it could mark the end of gasoline-powered cars.

The cost, weight, and insufficient lifespan of batteries represents a major obstacle to electric cars replacing internal combustion engines on our roads. There are two paths to address this: One, like Aesop’s tortoise, involves slow incremental improvements in existing lithium-ion batteries, collectively bringing down the cost and extending the range of electric vehicles.

The other path involves a shift to a radically better technology, of which the one with the greatest potential is lithium-oxygen, also known as lithium-air. The announcement in Nature Energy of a very different way of making lithium-oxygen batteries indicates it is not time to write off the hare in this race.

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