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Category: chemistry – Page 49

Even if we can dodge a disaster in orbit by responsibly de-orbiting derelict satellites, many scientists are concerned that the number of objects circling our planet could still do harm: When they deorbit, they could deposit a significant flux of metals that could alter the chemical makeup of Earth’s atmosphere.

“Effects on astronomy are just the tip of the iceberg,” said Barentine, who says we may be fast approaching a turning point where tragedy becomes imminent, either in space due to a collision or on the ground from falling debris. “Space policy-making moves far too slowly to effectively deal with all of this.”

“Right now, there’s not a lot to look forward to that is positive,” he added. “If the New Space Age goes badly in the end, history will not look favorably on it.”

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Lithium (Li) secondary batteries, commonly used in electric vehicles, store energy by converting electrical energy to chemical energy and generating electricity to release chemical energy to electrical energy through the movement of Li-ions between a cathode and an anode. These secondary batteries mainly use nickel (Ni) cathode materials due to their high lithium-ion storage capacity. Traditional nickel-based materials have a polycrystalline morphology composed of many tiny crystals which can undergo structural degradation during charging and discharging, significantly reducing their lifespan.

One approach to addressing this issue is to produce the cathode material in a “single-crystal” form. Creating nickel-based cathode materials as single large particles, or “single crystals,” can enhance their structural and chemical stability and durability. It is known that single-crystal materials are synthesized at high temperatures and become rigid. However, the exact process of hardening during synthesis and the specific conditions under which this occurs remain unclear.

To improve the durability of nickel cathode materials for electric vehicles, the researchers focused on identifying a specific temperature, referred to as the “critical temperature,” at which high-quality single-crystal materials are synthesized. They investigated various synthesis temperatures to determine the optimal conditions for forming single crystals in synthesis of a nickel-based cathode material (N884). The team systematically observed the impact of temperature on the material’s capacity and long-term performance.

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Dartmouth researchers have developed a self-powered pump that uses natural light and chemistry to target and remove specific water pollutants, according to a new report in the journal Science (“A molecular anion pump”).

As water enters the pump, a wavelength of light activates a synthetic molecular receptor designed to bond to negatively charged ions, or anions, a class of pollutants linked to metabolic disruptions in plants and animals. A second wavelength deactivates the receptors as water exits the pump and causes them to release the pollutants, trapping them in a non-reactive substrate until they can be safely discarded.

“This is a proof of concept that you can use a synthetic receptor to convert light energy into chemical potential for removing a contaminant from a waste source,” says the study’s senior author, Ivan Aprahamian, professor and chair of the Department of Chemistry at Dartmouth.

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The effective integration of extremely thin insulating layers with two-dimensional (2D) semiconductors could enable the fabrication of 2D transistors with an electrical capacitance comparable to SiO2 with thicknesses below 1-nm. These transistors could, in turn, help to boost the performance and reduce the power consumption of electronic devices.

Researchers at Nankai University in China recently introduced a new strategy to synthesize single-crystalline metal nanosheets that could be easily transferred onto 2D substrates. This strategy, outlined in a paper in Nature Electronics, was successfully used to deposit 2-nm-thick dielectrics based on Al2O3 or HfO2 for highly performing top-gated transistors.

“At the very beginning, we aimed to developing the (CVD) synthetic strategy of 2D Cu2O, which is a p-type high-mobility 2D semiconductor,” Jinxiong Wu, corresponding author of the paper, told Tech Xplore.

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NRL scientists have discovered new semiconductor nanocrystals with bright ground-state excitons, potentially revolutionizing light-emitting devices and resolving the dark-exciton problem.

Scientists at the U.S. Naval Research Laboratory (NRL) have confirmed the identification of a new class of semiconductor nanocrystals with bright ground-state excitons. This significant advancement in optoelectronics was recently published in the American Chemical Society (ACS) journal, ACS Nano.

The groundbreaking theoretical research could revolutionize the development of highly efficient light-emitting devices and other technologies.

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Mathematics application to a new understanding thd world and life and information.

Dr. David Spivak introduces himself as a keynote speaker at the 17th Annual Artificial General Intelligence Conference in Seattle and shares his lifelong passion for math. He discusses his journey from feeling insecure about the world as a child, to grounding his understanding in mathematics.

Dr. Spivak is the Secretary of the Board at the Topos Institute and on the Topos staff as Senior Scientist and Institute Fellow, following an appointment as founding Chief Scientist. Since his PhD from UC Berkeley in 2007, he has worked to bring category-theoretic ideas into science, technology, and society, through novel mathematical research and collaboration with scientists from disciplines including Materials Science, Chemistry, Robotics, Aeronautics, and Computing. His mission at Topos is to help develop the ability for people, organizations, and societies to see more clearly—and hence to serve—the systems that sustain them.

Continue reading “David Spivak: Pioneering Math for Understanding Reality | AGI-24 Keynote Preview” | >

Researchers at the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences, along with collaborators from leading international institutions, have introduced an innovative cathode homogenization strategy for all-solid-state lithium batteries (ASLBs).

This new approach, detailed in their recent publication in Nature Energy on July 31, significantly improves the life cycle and energy density of ASLBs, representing an important advancement in energy storage technology.

Current ASLBs face challenges due to heterogeneous composite cathodes, which require electrochemically inactive additives to enhance conduction. These additives, while necessary, reduce the batteries’ energy density and cycle life due to their incompatibility with the layered oxide cathodes, which undergo substantial volume changes during operation.

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“These spots are a big surprise,” said Dr. David Flannery. “On Earth, these types of features in rocks are often associated with the fossilized record of microbes living in the subsurface.”

Did Mars once have life billions of years ago? This is what NASA’s Perseverance (Percy) rover hopes to figure out, and scientists might be one step closer to answering that question with a recent discovery by the car-sized robotic explorer that found a unique rock with “leopard spots” that have caused some in the scientific community to claim this indicates past life might have once existed on the now cold and dry Red Planet. However, others have just as quickly rushed to say that further evidence is required before jumping to conclusions.

Upon analyzing the rock using Percy’s intricate suite of scientific instruments, scientists determined that it contained specific chemical signatures indicative of life possibly having existed billions of years ago when liquid water flowed across the surface. However, the science team is also considering other reasons for the rock’s unique appearance, including further research to determine if the findings are consistent with potential ancient life.

The unique features of the rock include calcium sulfate veins with reddish material between the veins which indicate the presence of hematite, which is responsible for the Red Planet’s rusty color. Upon further inspecting the reddish material, Percy identified dozens of off-white splotches at the millimeter-scale with black material surrounding it, hence the name “leopard spots”

Continue reading “Peculiar Rock Found by NASA’s Perseverance Rover Leaves Scientists Puzzled” | >