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Welcome to our free science videos for teens and pre-teens, hosted by the interactive online science program for young explorers, Art of Inquiry!
www.artofinquiry.net.

Our speaker, Dr. Joscha Bach talks with the Art of Inquiry students about his work.

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Topology and entanglement are two powerful principles for characterizing the structure of complex quantum states. In a new paper in the journal Physical Review X, researchers from the University of Pennsylvania establish a relationship between the two.

“Our work ties two big ideas together,” says Charles Kane, the Christopher H. Browne Distinguished Professor of Physics in Penn’s School of Arts & Sciences. “It’s a conceptual link between topology, which is a way of characterizing the universal features that quantum states have, and entanglement, which is a way in which quantum states can exhibit non-local correlations, where something that happens in one point in space is correlated with something that happens in another part in space. What we’ve found is a situation where those concepts are tightly intertwined.”

The seed for exploring this connection came during the long hours Kane spent in his home office during the pandemic, pondering new ideas. One train of thought had him envisioning the classic textbook image of the Fermi surface of copper, which represents the metal’s potential electron energies. It’s a picture every physics student sees, and one with which Kane was highly familiar.

The world is highly dependent on fossil fuels to power its industry and transportation. These fossil fuels lead to excessive carbon dioxide emission, which contributes to global warming and ocean acidification. One way to reduce this excessive carbon dioxide emission that is harmful to the environment is through the electroreduction of carbon dioxide into value-added fuels or chemicals using renewable energy. The idea of using this technology to produce methane has attracted wide interest. However, researchers have had limited success in developing efficient catalysts for methane.

A Soochow University research team has now developed a simple strategy for creating cobalt copper alloy catalysts that deliver outstanding methane activity and selectivity in electrocatalytic carbon dioxide reduction. Their research is published in Nano Research.

Over the past 10 years, scientists have made notable progress in advancing their understanding of catalysts and applying the knowledge to their fabrication. But the catalysts that have been developed have not been satisfactory for use with methane, in terms of selectivity or current density. Despite the great insights scientists have gained, the strategies they have attempted in creating catalysts for methane are just too costly to be useful in practical applications.

In recent years, ribonucleic acid (RNA) has emerged as a powerful tool for the development of novel therapies. RNA is used to copy genetic information contained in our hereditary material, the deoxyribonucleic acid (DNA), and then serves as a template for building proteins, the building blocks of life. Delivery of RNA into cells remains a major challenge for the development of novel therapies across a broad range of diseases. Researchers at the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) in Dresden together with researchers from the global biopharmaceutical company AstraZeneca have investigated where and how mRNA is delivered inside the cell. They found that mRNA uses an unexpected entry door. Their results provide novel insights into the development of RNA therapeutics towards efficient delivery and lower dosages.

DNA (deoxyribonucleic acid) contains the genetic information required for the development and maintenance of life. This information is communicated by messenger ribonucleic acid (mRNA) to make proteins. mRNA-based therapeutics have the potential to address unmet needs for a wide variety of diseases, including cancer and cardiovascular disease. mRNA can be delivered to cells to trigger the production, degradation or modification of a target protein, something impossible with other approaches. A key challenge with this modality is being able to deliver the mRNA inside the cell so that it can be translated to make a protein. mRNA can be packed into lipid nanoparticles (LNPs)—small bubbles of fat—that protect the mRNA and shuttle it into cells. However, this process is not simple, because the mRNA has to pass the membrane before it can reach its site of action in the cell interior, the cytoplasm.

Researchers in the team of MPI-CBG director Marino Zerial are experts in visualizing the cellular entry routes of molecules in the cell, such as mRNA with high-resolution microscopes. They teamed up with scientists from AstraZeneca who provided the researchers with lipid nanoparticle prototypes that they had developed for therapeutic approaches to follow the mRNA inside the cell. The study is published in the Journal of Cell Biology.

Nanoengineers at the University of California San Diego have developed a new and potentially more effective way to deliver messenger RNA (mRNA) into cells. Their approach involves packing mRNA inside nanoparticles that mimic the flu virus—a naturally efficient vehicle for delivering genetic material such as RNA inside cells.

The new mRNA delivery nanoparticles are described in a paper published recently in the journal Angewandte Chemie International Edition.

The work addresses a major challenge in the field of drug delivery: Getting large biological drug molecules safely into cells and protecting them from organelles called endosomes. These tiny acid-filled bubbles inside the cell serve as barriers that trap and digest large molecules that try to enter. In order for biological therapeutics to do their job once they are inside the cell, they need a way to escape the endosomes.

An international research team led by the University of Göttingen has detected novel quantum effects in high-precision studies of natural double-layer graphene and has interpreted them together with the University of Texas at Dallas using their theoretical work. This research provides new insights into the interaction of the charge carriers and the different phases, and contributes to the understanding of the processes involved. The LMU in Munich and the National Institute for Materials Science in Tsukuba, Japan, were also involved in the research. The results were published in Nature.

The novel material graphene, a wafer-thin layer of carbon atoms, was first discovered by a British research team in 2004. Among other unusual properties, graphene is known for its extraordinarily high electrical conductivity. If two individual graphene layers are twisted at a very specific angle to each other, the system even becomes superconducting (i.e. conducts electricity without any resistance) and exhibits other exciting quantum effects such as magnetism. However, the production of such twisted graphene double-layers has so far required increased technical effort.

This novel study used the naturally occurring form of double-layer graphene, where no complex fabrication is required. In a first step, the sample is isolated from a piece of graphite in the laboratory using a simple adhesive tape. To observe quantum mechanical effects, the Göttingen team then applied a high electric field perpendicular to the sample: the electronic structure of the system changes and a strong accumulation of charge carriers with similar energy occurs.

A sheet of magic-angle twisted bilayer graphene can host novel topological phases of matter, a study has revealed.

Magic-angle twisted graphene, first discovered in 2018, is made from two sheets of graphene (a form of carbon consisting of a single layer of atoms in a honeycomb-like lattice pattern), layered atop one another, with one sheet twisted at precisely 1.05 degrees with respect to the other. The resulting bilayer has unusual electronic properties: for example, it can be made into an insulator or a superconductor depending on how many electrons are added.

The discovery launched a new field of research into magic-angle twisted graphene, known as “twistronics.” At Caltech, Stevan Nadj-Perge, assistant professor of applied physics and materials science, has been among the researchers leading the charge: in 2019, he and his colleagues directly imaged the electronic properties of magic-angle twisted graphene at atomic-length scales; and in 2020, they demonstrated that superconductivity in twisted bilayer graphene can exist away from the magic angle when coupled to a two-dimensional semiconductor.

Electrons inhabit a strange and topsy-turvy world. These infinitesimally small particles have never ceased to amaze and mystify despite the more than a century that scientists have studied them. Now, in an even more amazing twist, physicists have discovered that, under certain conditions, interacting electrons can create what are called ‘topological quantum states.’ This finding, which was recently published in the journal Nature, has implications for many technological fields of study, especially information technology.

Topological states of matter are particularly intriguing classes of quantum phenomena. Their study combines quantum physics with topology, which is the branch of theoretical mathematics that studies geometric properties that can be deformed but not intrinsically changed. Topological quantum states first came to the public’s attention in 2016 when three scientists—Princeton’s Duncan Haldane, who is Princeton’s Thomas D. Jones Professor of Mathematical Physics and Sherman Fairchild University Professor of Physics, together with David Thouless and Michael Kosterlitz—were awarded the Nobel Prize for their work in uncovering the role of topology in electronic materials.

“The last decade has seen quite a lot of excitement about new topological quantum states of electrons,” said Ali Yazdani, the Class of 1909 Professor of Physics at Princeton and the senior author of the study. “Most of what we have uncovered in the last decade has been focused on how electrons get these topological properties, without thinking about them interacting with one another.”

Assembling Lego-like, 2D heterostructures can give rise to emergent properties and functionalities very different from the intrinsic characteristics of the constituents.

Density functional theory (DFT)-based band-structure calculations can shed light on interfacial properties of different heterostructures.