Tag Archives: SPHERES

Making magnetic rust behave like gold and the nanoscale

Researchers at the University of Georgia (US) have found a way to combine gold nanoparticles with magnetic rust nanoparticles for a hybrid structure that behaves with the properties of both types of nanoparticles. From a Sept. 15, 2016 news item on ScienceDaily,

Researchers from the University of Georgia are giving new meaning to the phrase “turning rust into gold”—and making the use of gold in research settings and industrial applications far more affordable.

The research is akin to a type of modern-day alchemy, said Simona Hunyadi Murph, adjunct professor in the UGA Franklin College of Arts and Sciences department of physics and astronomy. Researchers combine small amounts of gold nanoparticles with magnetic rust nanoparticles to create a hybrid nanostructure that retains both the properties of gold and rust.

A Sept. 15, 2016 University of Georgia news release by Jessica Luton, which originated the news item, expands on the theme,

“Medieval alchemists tried to create gold from other metals,” she said. “That’s kind of what we did with our research. It’s not real alchemy, in the medieval sense, but it is a sort of 21st century version.”

Gold has long been a valuable resource for industry, medicine, dentistry, computers, electronics and aerospace, among others, due to unique physical and chemical properties that make it inert and resistant to oxidation. But because of its high cost and limited supply, large scale projects using gold can be prohibitive. At the nanoscale, however, using a very small amount of gold is far more affordable.

In the new study published this summer in the Journal of Physical Chemistry C, the researchers used solution chemistry to reduce gold ions into a metallic gold structure using sodium citrate. In this process, if other ingredients-rust in this case-are present in the reaction pot during the transformation process, the metallic gold structures nucleate and grow on these “ingredients,” otherwise known as supports.

“We are really excited to share our new discoveries. When researchers are looking at gold as a potential material for research, we talk about how expensive gold is. For the first time ever, we’ve been able to create a new class of cheaper, highly efficient, nontoxic, magnetically reusable hybrid nanomaterials that contain a far more abundant material-rust-than the typical noble metal gold,” said Murph, who is also a principal scientist in the National Security Directorate at the Savannah River National Laboratory in Aiken, South Carolina.

When materials are broken down in size to reach nanometer scale dimensions-1-100 nanometers, which is approximately 100,000 times smaller than the diameter of human hair-these substances can take on new properties. For example, bulk gold does not display catalytic properties; however, at the nanoscale, gold is an efficient catalyst, accelerating chemical change for many reactions including oxidation, hydrogen production or reduction of aromatic nitro compounds.

Gold nanoparticles of different sizes and shapes display different colors when impinged by light because they absorb and scatter light at specific wavelengths, known as plasmonic resonances. These plasmonic resonances are of particular interest for biological applications. If someone shines light on the gold nanoparticles, the absorbed light can be converted to heat in the surrounding media, and if bacteria or cancerous cells are in the vicinity of such gold nanoparticles, they can be destroyed by using light of appropriate wavelength. This phenomenon is known as photothermal therapy.

By replacing some of the nano-gold with magnetic nano-rust, researchers show that the hybrid gold and rust nanostructures are able to photothermally heat the surrounding media as efficiently as pure gold nanoparticles, even with a significantly smaller concentration of gold.

“In a way, we’ve done a little better than alchemy,” said George Larsen, co-investigator and postdoctoral researcher in the Group for Innovation and Advancements in Nano-Technology Sciences at the Savannah River National Laboratory, “because these new hybrid nanoparticles not only behave better than gold in some cases, but also have magnetic functionality.”

Murph and her team looked at three different shapes of hybrid nanoparticles in this research-spheres, rings and tubes.

“A differently shaped nanoparticle means that the atoms are arranged differently-into cubes, hexagons or triangles, for example,” she said. “A different atom arrangement means different packing densities, spacing between atoms, defects, surface area and surface energies. Different shapes lead to an increased atom area that is exposed to catalyze a chemical reaction. Scientifically speaking, different shape means different crystallographic facets and surface energy that could lead to higher catalytic activity and different catalytic products.

“The results of our research showed that the ring- and tube-shaped hybrid nanoparticles proved to be better catalytic materials than the sphere-shaped nanoparticles because of the way the atoms are arranged in the structure at this nanoscale. More importantly, the hybrid nanoparticles of gold and rust are better catalysts than gold nanoparticles alone, even with a significantly smaller amount of gold.

When these different shaped hybrid nanoparticles were exposed to light of specific wavelength, the spheres heated the solution up to slightly higher temperatures than the ring- or tube-shaped nanoparticles.

“This could have a variety of biological applications such as tracking, drug delivery or imaging inside the body,” Murph said. “If you feed these gold nanoparticles to bacteria and shine the light on them, you could destroy these by just using light.”

The hybrid structures could also be used for new application [sic], such as sensing, hyperthermia treatment, environmental cleaning and protection medical imaging applications including magnetic resonance imaging contrast agents, product detection and manipulation.

Here’s a link to and a citation for the paper/video,

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating by Simona E. Hunyadi Murph, George K. Larsen, Robert J. Lascola. Journal of Visualized Experiments, 2016; (108) DOI: 10.3791/53598

This paper/video appears to be open access.

Informal science education, DARPA and NASA style

I like to mention imaginative science education projects from time to time and this one caught my attention. The US National Aeronautics and Space Administration (NASA) and the Defense Advanced Research Projects Agency (DARPA) are offering students the opportunity to have one of their experiments tested under live conditions in outer space. From the Kit Eaton June 20, 2011 article (How NASA, DARPA Are Keeping Kids Interested In Space),

To keep folks interested [now that the Space Shuttle era is over], NASA and DARPA are pushing (a little) money into a program that’s directly aimed at students themselves.

Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) are an existing experiment that uses tiny ball-shaped robots that fly inside the International Space Station. They test techniques for keeping real satellites maneuvering in sync so that they can rendezvous and work as part of a swarm–a task that’s useful for autonomous satellite servicing, and even the building of future spacecraft.

The offer that NASA’s making is that if you design an interesting experiment, and it wins their approval, it’ll be used to fly the SPHERES robots for real. In space.

There are more details about the 2011 SPHERES Challenge tournament at the Massachusetts Institute of Technology’s (MIT) Zero Robotics website. Here’s a little of the information available on that site,

“Zero Robotics” is a robotics programming competition that opens the world-class research facilities on the International Space Station (ISS) to high-school students. Students will actually write programs at their High School that may control a satellite in space! The goal is to build critical engineering skills for students, such as problem solving, design thought process, operations training, and team work. Ultimately we hope to inspire future scientists and engineers so that they will view working in space as “normal”, and will grow up pushing the limits of engineering and space exploration.

They’ve had annual challenges since 2009 and this year’s is the SPHERES challenge. There are six stages to this year’s competition,

The 2011 SPHERES Challenge tournament has 6 stages:

  1. Learn to program / tutorials / initial programming
  2. 2D Simulation: the game will be played in 2-dimensions. All teams will submit a player and will compete, in a full round robin simulation, against all other teams. Their score will count towards elimination later on, but no teams will be eliminated in this round.
  3. 2D Ground Competition: the top scorers from the 2D simulation will see their players compete against each other on the SPHERES ground satellites, learning directly some of the important differences between simulation and real hardware. Scores in this round will not count towards elimination, as not all teams will compete. All teams will be able  to watch the competition at MIT via webcast.
  4. 3D Simulation: all participating teams will extend their game to 3 dimensions and submit their final individual player. MIT will run a full round robin simulation. The score of this round will be combined with the score of the 2D simulation to seed all teams.
  5. 3D Semi-Finals: the top 48 teams will be required to form alliances of 3 teams per player, creating a total of 16 players. Preference will be given to the choices of higher seeds. These alliances will compete in a full round-robin simulation. The top scoring players/alliances will be invited to submit an entry for the ISS finals.
  6. ISS Finals: the top 9 players of the semi-finals will be invited to participate in the ISS finals (a total of 27 teams, as there will be 3 teams per player).  Teams may visit MIT to see the live feed, or watch via the webcast. Players will compete in a bracketed round-robin aboard the ISS and a champion will be declared.   (note: date depends on astronaut time availability)

This is a competition for US high school students from grades 9 – 12.  The application deadline is Sept. 5, 2011.