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Category: chemistry – Page 144

Using a high-speed “electron camera” at the Department of Energy’s SLAC National Accelerator Laboratory and cutting-edge quantum simulations, scientists have directly imaged a photochemical “transition state,” a specific configuration of a molecule’s atoms determining the chemical outcome, during a ring-opening reaction in the molecule α-terpinene. This is the first time that scientists have precisely tracked molecular structure through a photochemical ring-opening reaction, triggered when light energy is absorbed by a substance’s molecules.

The results, published in Nature Communications, could further our understanding of similar reactions with vital roles in chemistry, such as the production of vitamin D in our bodies.

Transition states generally occur in which are triggered not by light but by heat. They are like a point of no return for molecules involved in a chemical reaction: As the molecules gain the energy needed to fuel the reaction, they rearrange themselves into a fleeting configuration before they complete their transformation into new molecules.

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Coccolithophores, a globally ubiquitous type of phytoplankton, play an essential role in the cycling of carbon between the ocean and atmosphere. New research from Bigelow Laboratory for Ocean Sciences shows that these vital microbes can survive in low-light conditions by taking up dissolved organic forms of carbon, forcing researchers to reconsider the processes that drive carbon cycling in the ocean. The findings were published this week in Science Advances.

The ability to extract carbon from the direct absorption of dissolved organic carbon is known as osmotrophy. Though scientists had previously observed osmotrophy by coccolithophores using lab-grown cultures, this is the first evidence of this phenomenon in nature.

The team, led by Senior Research Scientist William Balch, undertook their experiments in populations of coccolithophores across the northwest Atlantic Ocean. They measured the rate at which phytoplankton fed on three different organic compounds, each labeled with chemical markers to track them. The dissolved compounds were used by the coccolithophores as a for both the organic tissues that comprise their single cells as well as the inorganic mineral plates, called coccoliths, which they secrete around themselves. Uptake of the organic compounds was slow compared to the rate at which phytoplankton can take up carbon through photosynthesis. But it wasn’t negligible.

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When most people think of crystals, they picture suncatchers that act as rainbow prisms or the semi-transparent stones that some believe hold healing powers. However, to scientists and engineers, crystals are a form of materials in which their constituents—atoms, molecules, or nanoparticles—are arranged regularly in space. In other words, crystals are defined by the regular arrangement of their constituents. Common examples are diamonds, table salt, or sugar cubes.

However, in research just published in Soft Matter, a team led by Rensselaer Polytechnic Institute’s Sangwoo Lee, associate professor in the Department of Chemical and Biological Engineering, discovered that crystal structures are not necessarily always regularly arranged. The discovery advances the field of materials science and has unrealized implications for the materials used for semiconductors, solar panels, and electric vehicle technologies.

One of the most common and important classes of crystal structures is the close-packed structures of regular spheres constructed by stacking layers of spheres in a honeycomb arrangement. There are many ways to stack the layers to construct close-packed structures, and how nature selects specific stacking is an important question in materials and physics research. In the close-packing construction, there is a very unusual structure with irregularly spaced constituents known as the random stacking of two-dimensional hexagonal layers (RHCP). This structure was first observed from cobalt metal in 1942, but it has been regarded as a transitional and energetically unpreferred state.

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Electrifying transportation is an essential step towards mitigating climate change. To improve the power, efficiency and safety of electric vehicles, researchers must continue to develop better batteries.

All-solid-state lithium batteries (SSBs), which have a solid electrolyte instead of a liquid, are safer than traditional lithium-ion batteries because they are less flammable and more stable at higher temperatures. They could also have higher energy densities than lithium-ion batteries, allowing for longer lasting batteries in smaller sizes for portable electronics and other applications.

A research team led by Joshua Gallaway of Northeastern University in Boston and scientists at the Department of Energy’s (DOE) Argonne National Laboratory recently tested how the composition of thick cathodes affected electrochemical reactions in SSBs. The team used the resources of the Advanced Photon Source (APS), a DOE Office of Science user facility at Argonne. Their discoveries were published in the journal ACS Energy Letters.

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A University of Minnesota Twin Cities-led team has developed a first-of-its-kind, breakthrough method that makes it easier to create high-quality metal oxide thin films out of “stubborn” metals that have historically been difficult to synthesize in an atomically precise manner. This research paves the way for scientists to develop better materials for various next-generation applications including quantum computing, microelectronics, sensors, and energy catalysis.

The researchers’ paper is published in Nature Nanotechnology.

“This is truly remarkable discovery, as it unveils an unparalleled and simple way for navigating material synthesis at the atomic scale by harnessing the power of epitaxial strain,” said Bharat Jalan, senior author on the paper and a professor and Shell Chair in the University of Minnesota Department of Chemical Engineering and Materials Science.

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Biosensors are artificial molecular complexes designed to detect the presence of target chemicals or even biomolecules. Consequently, biosensors have become important in diagnostics and synthetic cell biology. However, typical methods for engineering biosensors focus on optimizing the interactions between static binding surfaces, and current biosensor designs can only recognize structurally well-defined molecules, which can be too rigid for “real-life” biology.

“We developed a novel computational approach for designing protein-peptide ligand binding and applied it to engineer cell-surface chemotactic receptors that reprogrammed cell migration,” says EPFL professor Patrick Barth. “We think that our work could broadly impact the design of protein binding and cell engineering applications.”

The new biosensors developed by Barth’s group can sense flexible compounds and trigger complex cellular responses, which open up new possibilities for biosensor applications. The researchers created a , which is a computer-based system, for designing protein complexes that can change their shape and function dynamically—as opposed to the conventional static approaches. The framework can look at previously unexplored protein sequences to come up with new ways for the protein’s groups to be activated, even in ways that are different to their natural function.

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In my work, I build instruments to study and control the quantum properties of small things like electrons. In the same way that electrons have mass and charge, they also have a quantum property called spin. Spin defines how the electrons interact with a magnetic field, in the same way that charge defines how electrons interact with an electric field. The quantum experiments I have been building since graduate school, and now in my own lab, aim to apply tailored magnetic fields to change the spins of particular electrons.

Research has demonstrated that many physiological processes are influenced by weak magnetic fields. These processes include stem cell development and maturation, cell proliferation rates, genetic material repair, and countless others. These physiological responses to magnetic fields are consistent with chemical reactions that depend on the spin of particular electrons within molecules. Applying a weak magnetic field to change electron spins can thus effectively control a chemical reaction’s final products, with important physiological consequences.

Currently, a lack of understanding of how such processes work at the nanoscale level prevents researchers from determining exactly what strength and frequency of magnetic fields cause specific chemical reactions in cells. Current cell phone, wearable, and miniaturization technologies are already sufficient to produce tailored, weak magnetic fields that change physiology, both for good and for bad. The missing piece of the puzzle is, hence, a “deterministic codebook” of how to map quantum causes to physiological outcomes.

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