A collection of iron oxide nanoparticles (blue) and smaller lead selenide nanoparticles (red) -- a.k.a. quantum dots -- beginning to interact and organize in solution on their way to crystallizing into a binary superlattice. The resulting assembly captures the magnetic properties of the iron oxide while retaining the distinct optical signature of the quantum dots.
A schematic of a binary superlattice where thirteen small lead selenide quantum dots (red) are grouped together, filling the spaces between the 11 nm diameter iron oxide (blue). The distance between the iron oxide particle is exaggerated to allow a clear view of how the lead selenide particles pack together.
Scientists from Columbia University, IBM and the University of New Orleans today announced a new, three-dimensional designer material assembled from two different types of particles only billionths of a meter across.
In the June 26 issue of the journal Nature, the team describes the precision chemistry methods developed to tune the particles’ sizes in increments of less than one nanometer and to tailor the experimental conditions so the particles would assemble themselves into repeating 3-D patterns. The work was supported in part by the National Science Foundation, the independent agency that supports basic research in all fields of science and engineering, through the Center for Nanostructured Materials at Columbia University and by the Defense Advanced Research Agency (DARPA) through programs on metamaterials and advanced thermoelectric materials.
Designing new materials with otherwise unattainable properties, sometimes referred to as "metamaterials," is one of the promises of nanotechnology. Two-dimensional patterns had previously been created from gold nanoparticles of different sizes and mixtures of gold and silver. Extending this concept to three dimensions with more diverse types of materials demonstrates the ability to bring more materials together than previously realized.
David Hart | National Science Foundation
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Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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