Helium Ion Microscopy Reveals Mysteries of Iron-Oxide Covered Bacteria

Some iron-oxidizing bacteria make organic-mineral filaments that extend from their surfaces. But how they are formed remains a puzzle. Now, using helium ion microscopy (HIM), James M. Byrne of the University of Tübingen and his colleagues have captured these stalks forming in unprecedented detail (Environ. Sci. Technol. Lett. 2018, DOI: 10.1021/acs.estlett.8b00077). Previous imaging efforts used scanning electron microscopy, but this technique has inferior resolution and in this context requires coatings that distort the structures being studied.

The group cultured bacteria isolated from low-oxygen sediments in a Denmark bay and analyzed the samples with HIM over a month to document how the structures changed. First, spiral-shaped stalks formed. Eventually, mineral crystals coated the spirals so heavily that their shapes were no longer discernible. “It really blew my mind when we started to see these objects forming,” Byrne says. The spirals were mostly organic, whereas the mineral deposits were lepidocrocite, an iron oxide-hydroxide mineral, elemental analysis showed. Some researchers think the structures sequester toxic, dissolved iron(II) in the environment as insoluble iron(III), protecting the microbes. More work may solve that mystery, too.

Magnetic Quiz - We Have Two Winners

In preparation of our 2018 Magnetic Carrier Meeting, Vitalii Zablotskii made up a small quiz about magnetism. It was not easy, and nobody could answer all the questions correctly. But we had two conference participants who got the same high score. As a thank you, they received a magnetic knife holder - something really useful for your kitchen.

If you have not answered the quiz questions yet, you might give it a try  with the the questions here. And if you think you got it all right, check to see Vitalii's answers here. Did you get it all correctly?

Thank you very much Vitalii for preparing this for us! And by the way, there will be another quiz coming up in the near future. Keep posted.

Big Honor for Maxim Nikitin

Russia's President Vladimir Putin presented our own physicist/mathematician Maxim Nikitin of Moscow Institute of Physics and Technology (MFTI) on February 8, 2018 with an award to young researchers and scientists at the House of Scientists (Scientists' Club) of the Siberian Branch of the Russian Academy of Sciences. Well deserved Maxim!

Hear of Magnetic Surgery, Anybody?

In recent years, magnetic compression anastomosis (MCA) developed quickly. Many breakthroughs and innovations were made in the magnetic anchoring technology (MCT) and magnetic navigation technology (MNT). The development of these technologies started a new research field of magnetic surgery. However, many key problems have not been solved yet. For this reason, Xi'an Jiaotong University under the guidance of president Yi Lv is organizing the 1st International Congress of Magnetic Surgery (ICMS-2018) ,which will be held from June 1-3, 2018 in Xi'an, China.

It does not seem that the people in this group use magnetic particles yet, but who knows what the future brings! Check out the program at http://icms.medmeeting.org/Content/92865.

Magnetic Carrier Meeting 2018 in Copenhagen

Our 12th International Conference on the Scientific and Clinical Applications of Magnetic Carriers took place at the University of Copenhagen's new Maersk building.from May 22-26, 2018. Most of the 328 participants are visible from the picture below - click on it to get a higher resolution version.

If you want to check out the program, the entire abstract booklet is available online.

Weird Magnetic Effect Could Improve Computer Memory

For decades, applied physicists and semiconductor companies have developed computer memory that uses the direction of a magnetic field to store data. A magnetic pulse or a jolt of electricity can change the properties of an island of magnetic material, flipping its field up or down to represent a 1 or a 0. The primary advantage of this so-called magnetoresistive random access memory (MRAM) is its durability. Johns Hopkins University physicist Chia-Ling Chien developed memory that can be written using smaller pulses of current. This would reduce power requirements and improve the lifetime of the memory arrays. Chien worked with an experimental device made up of nanometer-thin layers of a cobalt-iron-boron ferromagnet, a metal oxide, and tungsten held between a pair of gold electrodes. The researchers could flip the polarization of the CoFeB magnet by applying current through the electrodes, but only in the presence of a magnetic field. The tungsten layer acts as a kind of electron filter, allowing in only electrons with a particular spin. The momentum of that spin gets transferred to the magnet and flips the field.

While studying this device, Chien’s team found something weird. They wanted to see what happened when they broke one of the memory devices. They added a layer of platinum under the tungsten, expecting it would cancel out the spin-switching effect. “Anyone who understands spin-orbit torque will realize this is a stupid thing to do, because tungsten and platinum have opposite spin currents.” But the device didn’t stop working. Instead, the team found they could switch the platinum-frosted device simply by applying an electrical current—no magnetic field required. This simplification means such devices should be less complicated to build and operate. For more info, see here.

Magnetic Particle Imaging (MPI) Guided Magnetic Hyperthermia Therapy

Zhi Wei Tay et al. describe in the newest ACS Nano article how the labs of Steven Connolly and Carlos Rinaldi combined MPI and Magnetic Hyperthermia and tested successfully a theranostic platform for future cancer therapy. They showed experimental data using MPI gradients to deliver targeted heating on demand to components of a phantom with an ability to selectively heat targets separated by as little as 7 mm with negligible heating of off-target sites. Results from a rodent model are very promising.
MPI seems to be an excellent tool for thermal dose planning via an MPI pre-scan. Through a luciferase assay and histological assessment, they verified that heat damage was indeed localized to the target tumor. They further describe that an important next step is to develop MPI thermometry for in vivo implementation in order to provide a temperature feedback mechanism for complete thermal dose control.
Because achieving macroscopic heating with low amplitudes remains a challenge, another important direction is to explore MPI-magnetic hyperthermia for applications in targeted drug release by using the MPI gradient localization strategy to localize actuation of the drug-containing nanocarriers. Exploring other therapeutic approaches that do not require macroscopic temperature changes, such as activation of lysosomal pathways and thermal drug delivery, are also of great interest.

To read more, check out this link.

New Toyota Magnet Cuts Rare-Earth Use

The rise of electric vehicles is threatening supplies of a host of the earth’s elements. Cobalt and lithium for batteries are getting most of the attention, but rare earths for electric motors are also a pinch point. Now, Toyota Motor scientists have developed a new recipe for the motors’ permanent magnets that cuts reliance on particularly rare rare earths.

Permanent magnets keep electric motors turning in all kinds of devices, from electric toothbrushes to refrigerator compressors. In electric vehicles, the magnets need to last a long time without demagnetizing. They also have to stay stable at temperatures that can reach 100 ºC. To meet those requirements, the magnets are made up of 30% rare earths, to take advantage of their many unpaired electrons, and 70% iron. The go-to rare earth for powerful, durable magnets is neodymium.

Most of this pricey element comes from China, and Toyota says demand is expected to increase rapidly. Smaller amounts of terbium or dysprosium are added to neodymium to lend heat resistance, but those elements are even more expensive. Toyota has already cut terbium and dysprosium use in the 2016 Prius, and future magnets won’t use any, the firm promises. In addition, up to 50% of the neodymium will be replaced with the low-cost rare earths lanthanum and cerium.

To make the new recipe work, Toyota scientists reduced the size of the magnet’s grains to 0.25 micrometers, one-tenth their original size. They then concentrated neodymium on the surfaces of the smaller grains; the grains in standard magnets have the expensive element throughout. Looking inside the grains, they found that a 1:3 ratio of lanthanum to cerium is needed to prevent magnet performance from deteriorating.

Toyota says the new magnets could reach the market in the first half of the 2020s. They could also be used in robots and household appliances.