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Science Notebook

The Science News Round-up

Print edition : Sep 29, 2022 T+T-

The Science News Round-up

A harmonics function plot of a subject having a seizure in the left temporal lobe of the brain.

A harmonics function plot of a subject having a seizure in the left temporal lobe of the brain. | Photo Credit: IITD

Medicine, nuclear energy, and magnetics.

IIT Delhi comes up with non-invasive diagnostic tool for epilepsy

Epilepsy is the fourth most common neurological disorder in the world, affecting millions of people worldwide. It involves brief episodes of involuntary body (partial/entire) movement called seizures, primarily caused by erroneous excessive electrical discharges in the brain, that may be accompanied by loss of consciousness and control of bowel or bladder function.

Epilepsies are often controlled with medicines, though drug therapies sometimes fail owing to drug resistance. Drug-resistant epilepsies are most likely to originate from structural abnormalities of the brain, the cure for which is usually surgery.

These structural abnormalities are too subtle to be identified on the basis of MRIs alone and always need to be interpreted along with an electroencephalogram (EEG) evaluation. Neurosurgeons also utilise positron emission tomography (PET) scans and magnetoencephalography (MEG). However, PET scans involve exposure to radioactive substances, and India has a limited number of MEG facilities. Craniotomies (surgical removal of part of the bone from the skull to expose the brain) and robot-assisted surgeries are invasive, involving holes being drilled into the skull to place electrodes directly on the brain. It takes two to eight hours to detect the epileptogenic zone.

Now, a team of researchers at IIT Delhi led by Lalan Kumar of the Department of Electrical Engineering, and which included a scientist from Deenanath Mangeshkar Hospital and Research Centre, Pune, has come up with a non-invasive EEG-based Brain Source Localisation framework for epilepsy focal detection that is time efficient and patient friendly. Given the EEG data with seizure, array-processing algorithms can point the coordinates within minutes. “We have proposed utilisation of spherical harmonics and head harmonics basis functions for seizure localisation. To the best our knowledge, this is the first attempt in non-invasive and time efficient seizure localisation,” Kumar was quoted as saying in an IITD press release.  The study titled “Anatomical harmonics basis based brain source localization with application to epilepsy” was recently published in Nature Portfolio’s Scientific Reports.

NPCIL places its first order for fuel storage racks for Kudankulam

Early in August, Nuclear Power Corporation of India Limited (NPCIL) placed its first order for storage racks with Holtec Asia for its new away-from-reactor wet storage facility at the Kudankulam Nuclear Power Plant (KNPP) in Tirunelveli district, Tamil Nadu. The facility will serve units 1 and 2 at the plant. In these high-density racks neutron absorber materials are placed between fuel assemblies allowing their safe storage in close proximity to one another. The rack modules use Holtec’s proprietary detuned honeycomb technology and will be manufactured in India with METAMIC plates, which are the neutron-absorbing material, to be supplied by Holtec’s Orrvilon Manufacturing Facility, based in Ohio, US.

METAMIC is a boron carbide-aluminium alloy composite produced via a powder metallurgy process. According to World Nuclear News, the rack modules will be assembled by an NPCIL-approved supplier in collaboration with Holtec Asia’s manufacturing plant in Dahej, Gujarat. Holtec Asia’s engineering and design centre in Pune, Maharashtra, will administer and coordinate the project with NPCIL in Mumbai.

Units 1 and 2 at the Kudankulam Nuclear Power Plant in Tirunelveli district, Tamil Nadu.
Units 1 and 2 at the Kudankulam Nuclear Power Plant in Tirunelveli district, Tamil Nadu. | Photo Credit: KNPP

In February, NPCIL had placed an order with Holtec Asia to supply HI-STAR transport casks to serve this new away-from-reactor storage facility. It also issued a call for tenders for the construction of a used fuel storage facility for the third and fourth units currently under construction at Kudankulam.

NPCIL also recently awarded a contract, worth about Rs.500 crore, to the German pump manufacturer KSB Ltd for the supply of eight primary coolant pumps for units 5 and 6 at the Kaiga nuclear power plant in Karnataka. The deliveries of the pumps, including the electric motors and spares, are expected to begin in 2026. The contract is the second one on the company after the 2018 order for eight primary coolant pumps for Gorakhpur units 1 and 2 in Haryana.

Hybrid magnet in China produces record-breaking steady field of 45.22 T

On August 12, the hybrid magnet built by scientists of the Steady High Magnetic Field Facility (SHMFF) in Hefei, China, produced a steady field of 45.22 tesla (T), which is a world record for the highest steady magnetic field strength by an operational working magnet. The highest field strength achieved before this was 45 T in 1999, also with a hybrid magnet, at the National High Magnetic Field Laboratory (MagLab) in Florida, US. (The earth’s magnetic field is about 35 microtesla; the strength of a refrigerator magnet is a few millitesla; pulsed magnetic fields can be orders of magnitude greater than the steady field achieved in laboratories).

MagLab and SHMFF employed different ways of creating a magnetic field in combination, hence hybrid: an outer superconducting ring and an inner resistive Bitter electromagnet. Bitter magnets, invented in 1933 and used to achieve very high magnetic fields, are made of circular conducting metal plates and insulating spacers stacked in a helical configuration. The record-breaking 45.22 T hybrid magnet is composed of a resistive insert nested in a superconducting outer ring with a bore of 32 mm.

The graph shows the magnetic field strength contributions and record.
The graph shows the magnetic field strength contributions and record. | Photo Credit: SHMFF

Both technologies have their limitations. While the superconducting magnet has low power input needs but an upper limit on magnetic field strength, the Bitter magnet requires a much higher power input. Combining the two mitigates these limitations significantly and enables propagation of a powerful, steady magnetic field. 

In 2016, the Chinese team succeeded in fabricating a hybrid magnet that generated a central magnetic field of 40 T, which at the time made it the second strongest field strength achieved in the world. “To achieve higher magnetic field, we innovated the structure of the magnet and developed new materials,” Professor Kuang Guangli, the academic director of High Magnetic Field Laboratory of the Hefei Institutes of Physical Science, said in a statement. “The manufacturing process of the Bitter discs was also optimised,” he added.

The NIF in California gets one step closer to nuclear fusion

In August 2021, a nuclear fusion reaction triggered at the National Ignition Facility (NIF) in California, US, generated more energy than the energy that directly went into heating the target capsule where the reaction took place. Now, a year later, the team has confirmed that the reaction met another important milestone: ignition.

The NIF uses the largest laser in the world to heat and compress a small capsule containing hydrogen fuel and thereby induce nuclear fusion reactions in the fuel. Here, an artist’s rendering of laser beams entering the capsule through openings on either end.
The NIF uses the largest laser in the world to heat and compress a small capsule containing hydrogen fuel and thereby induce nuclear fusion reactions in the fuel. Here, an artist’s rendering of laser beams entering the capsule through openings on either end. | Photo Credit: National Ignition Facility

Ignition in fusion is defined by what is called the Lawson criterion, which is a figure of merit that compares the rate of energy generated by fusion reactions in the fusion fuel to the rate of energy losses to the environment. When the rate of production is higher than the rate of loss, the system will produce net energy. If enough of that energy is captured by the fuel to trigger fusion reactions within it, the system will become self-sustaining and is said to be ignited. This is exactly what happens when paper, wood, or coal is burnt: the heat from the burning part increases the temperature locally and sets fire to the adjacent, previously cold, fuel. The NIF uses the largest laser in the world to heat and compress a small capsule containing hydrogen fuel and thereby induce nuclear fusion reactions in the fuel. 

After the initial announcement about the fusion reaction last year, the researchers confirmed that the reaction achieved ignition according to nine different forms of the Lawson criterion. This makes the August 2021 fusion reaction the first laboratory fusion experiment to achieve ignition, bringing researchers another step closer to a Holy Grail of physics: nuclear fusion reactions that produce more energy than they consume. The achievement will have implications for nuclear fusion as a source of energy. The results were published in the August 8 issue of Physical Review Letters and Physical Review E.