The double helix is not the only structure formed by DNA and RNA. Guanine-rich DNA and RNA sequences can fold into quadruple-helix structures called G-quadruplexes. Recently, researchers visualized the unfolding of a G-quadruplex by a protein called DHX36, gaining valuable insight into a potential target for drug development. Read more »
Science Briefs
Ordered Magnetic Patterns in a Disordered Magnetic Material
Scientists have confirmed the presence of chirality, or handedness, in nanometers-thick samples of amorphous (noncrystalline) multilayer materials. The chirality—which potentially could be exploited to transmit and store data in a new way—was observed in the domain walls between neighboring regions of opposite spin. Read more »
Nanoscale Characterization of Iron and Calcium in the Alzheimer’s Brain
The amyloid plaques that accumulate in Alzheimer’s disease contain stores of iron. Using scanning transmission x-ray microscopy, researchers have characterized the iron’s chemical states in unprecedented detail. Their nanoscale analysis revealed excessive chemical reduction of the iron, which can release damaging free radicals. Read more »
New Manganese Materials Bolster Cathode Capacity
The most expensive component of a battery, the cathode, requires rare transition metals like cobalt. Previous attempts to replace cobalt with inexpensive and non-toxic manganese delivered insufficient performance. Now, researchers have optimized the composition of high-energy-density, high-capacity manganese-based cathodes. Read more »
Oxygen Vacancies Matter in the LaNiO3 Metal–Insulator Transition
Electronic structure measurements using x-ray absorption spectroscopy suggest that oxygen vacancies contribute to the metal–insulator transition in ultrathin films of LaNiO3. The results give scientists another “knob” to turn to tune this important transition, which could be useful for making advanced electronic devices. Read more »
Open and Shut: Pain Signals in Nerve Cells
Researchers used x-ray data to define the structure of a closed protein gate important for neuronal signaling. Comparing the closed gate with previously known structures of the same gate when open, researchers now have a comprehensive picture of proton-dependent channels in neurons. Read more »
New Clues to Oxygen’s Role in Higher-Capacity Batteries
As battery electrodes, layered transition-metal (TM) oxides demonstrate storage capacities far beyond what’s explained solely by TM redox activity. In this work, measurements of the lattice oxygen redox activity in two lithium-rich layered oxides showed strong oxygen redox when manganese was the TM, but not with ruthenium. Read more »
3D Localization of Nanoscale Battery Reactions
A new tool lets researchers pinpoint the locations of chemical reactions happening inside batteries in three dimensions at the nanoscale level. Combining ptychography, tomography, and spectroscopy, Nanosurveyor 1 is a multidimensional tool providing novel insight into the design of next-generation batteries and devices. Read more »
Scientists Use Machine Learning to Span Scales in Shale
Machine-learning techniques have been used to integrate fine- and large-scale infrared characterizations of shale—sedimentary rocks composed of minerals and organic matter. Understanding shale chemistry at both the nano and mesoscale is relevant to energy production, climate-change mitigation, and sustainable water and land use. Read more »
Clarifying the Working Principle of a High-Capacity Battery Electrode
Operando x-ray absorption spectroscopy experiments revealed the electrochemical reaction mechanism of molybdenum disulfide (MoS2) electrodes in lithium-ion battery cells. The work unambiguously clarifies that the MoS2 conversion reaction is not reversible and that the Li2S formed is converted to sulfur in the first charge process. Read more »
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