Manufacturing Bits: Aug. 4

Advancing rheometry; measuring astatine.


Advancing rheometry
The National Institute of Standards and Technology (NIST) has developed a new technology that could advance the field of rheometry.

More specifically, NIST has developed a new and advanced capillary rheometer. Rheometry is the study of the flow of liquids, gases or matter in systems. A capillary rheometer is an instrument, which measures the flow properties and shear viscosity in a system, according to Instron, a supplier of these and other products.

Credit: R. Murphy/NIST

NIST’s technology, called the Capillary RheoSANS (CRSANS), consists of a meter-long tube, which is coiled up like a spring. This part makes up the capillary rheometry unit. This unit is combined with a small-angle neutron scattering (SANS) instrument. A SANS tool measures material structures at the nanoscale. A neutron beam passes through the tube, which conducts the measurements.

In operation, a fluid is injected into the tube and it careens around a three-centimeter-wide loop at high speeds. The SANS tool measures the viscosity and nanostructure of the complex fluids at high shear rates.

The device can push fluids through a narrow tube at about 110 km per hour. The tube’s inner diameter is typically 100 micrometers. That equates to a train moving through a subway tunnel about 100 times faster than a rocket blasting its way into orbit, according to NIST.

NIST’s technology can be used in several industries, such as chemical, pharmaceutical and oil. These companies make fluids with complex substances. They need to know what happens to the fluid as it moves down narrow passages at high pressures.

Initially, NIST has used the technology for a new class of therapeutic proteins known as monoclonal antibodies, which show promise for treating cancer and other diseases. Another substance the team looked at were surfactants.

In general, there are several unknowns when dealing with new materials and substances. The flow properties are also a big unknown. “We don’t know what the structures of these fluids are at extreme conditions,” said Ryan Murphy, a researcher at NIST. “It’s easy to test when they’re moving slowly, but when you pump them out fast at high pressures you want to know what they’re going to do.”

Measuring astatine
A group of researchers at the European Organization for Nuclear Research (CERN) for the first time have measured the electron affinity of the chemical element astatine.

Astatine, a chemical element with the symbol At, is the rarest naturally occurring element on Earth. Astatine is a promising candidate for cancer treatments.

Discovered in the 1940s, astatine is a member of the halogen family, which includes chlorine and iodine, according to CERN. The problem? Astatine’s isotopes are short-lived and a sample of the pure element has never been assembled. Astatine vaporizes by the heat of its own radioactivity.

Using the ISOLDE nuclear-physics facility at CERN, researchers have measured the so-called electron affinity of this rare element. “The electron affinity is the energy released when an electron is added to a neutral atom in the gas phase to form a negative ion,” according to CERN.

Astatine atoms were produced along with other atoms by firing a high-energy beam of protons from CERN’s Proton Synchrotron Booster at a thorium target. The Proton Synchrotron Booster consists of four superimposed synchrotron rings.

The astatine atoms were then negatively ionized. The ions of the isotope were extracted and sent to a special measurement device. For this, a laser light of tunable energy hit the ions, which in turn measures the energy required to extract the extra electron of the ion and turn the ion into a neutral atom.

These properties are relevant for studies investigating the possible use of compounds in a targeted alpha therapy, a treatment that delivers alpha radiation to cancer cells, according to CERN. “Our results could be used to improve our knowledge of this release reaction and the stability of the compounds being considered for targeted alpha therapy,” said David Leimbach, a researcher in the study. “In addition, our findings pave the way to measurements of the electron affinity of elements heavier than astatine, potentially of the superheavy elements, which are produced one atom at a time.”

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