Hexbyte Glen Cove Pathway to forerunner of rugged nanotubes that could lead to widespread industrial fabrication thumbnail

Hexbyte Glen Cove Pathway to forerunner of rugged nanotubes that could lead to widespread industrial fabrication

Hexbyte Glen Cove

Author and co-authors with figure from paper. Clockwise from top left: Lead author Yuri Barsukov with co-authors Igor Kaganovich, Alexander Khrabry, Omesh Dwivedi, Sierra Jubin, Stephane Ethier. Credits: Batalova Valentina, Elle Starkman/Office of Communications, Elle Starkman, Han Wei, Hannah Smith, Elle Starkman. Credit: Elle Starkman.

Scientists have identified a chemical pathway to an innovative insulating nanomaterial that could lead to large-scale industrial production for a variety of uses – including in spacesuits and military vehicles. The nanomaterial—thousands of times thinner than a human hair, stronger than steel and noncombustible—could block radiation to astronauts and help shore up military vehicle armor, for example.

Collaborative researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have proposed a step-by-step chemical pathway to the precursors of this nanomaterial, known as boron nitride nanotubes (BNNT), which could lead to their large-scale production. 

“Pioneering work”

The breakthrough brings together  and quantum chemistry and is part of the expansion of research at PPPL. “This is pioneering work that takes the Laboratory in new directions,” said PPPL physicist Igor Kaganovich, principal investigator of the BNNT project and co-author of the paper that details the results in the journal Nanotechnology.

Collaborators identified the key chemical pathway steps as the formation of molecular nitrogen and small clusters of boron, which can chemically react together as the temperature created by a plasma jet cools, said lead author Yuri Barsukov of the Peter the Great St. Petersburg Polytechnic University. He developed the chemical reaction pathways by performing quantum chemistry simulations with the assistance of Omesh Dwivedi, a PPPL intern from Drexel University, and Sierra Jubin, a graduate student in the Princeton Program in Plasma Physics.

The interdisciplinary team included Alexander Khrabry, a former PPPL researcher now at Lawrence Livermore National Laboratory who developed a thermodynamic code used in this research, and PPPL physicist Stephane Ethier who helped the students compile the software and set up the simulations. 

The results solved the mystery of how molecular nitrogen, which has the second strongest chemical bond among diatomic, or double-atom molecules, can nonetheless break apart through reactions with boron to form various boron-nitride molecules, Kaganovich said. “We spent considerable amount of time thinking about how to get boron – nitride compounds from a mixture of boron and nitrogen,” he said. “What we found was that small clusters of boron, as opposed to much larger boron droplets, readily interact with nitrogen molecules. That’s why we needed a quantum chemist to go through the detailed quantum chemistry calculations with us.”

BNNTs have properties similar to carbon nanotubes, which are produced by the ton and found in everything from sporting goods and sportswear to dental implants and electrodes. But the greater difficulty of producing BNNTs has limited their applications and availability. 

Chemical pathway

Demonstration of a to the formation of BNNT precursors could facilitate BNNT production. The process of BNNT synthesis begins when scientists use a 10,000-degree plasma jet to turn boron and nitrogen gas into plasma consisting of free electrons and atomic nuclei, or ions, embedded in a background gas. This shows how the process unfolds:

  • The jet evaporates the boron while the molecular nitrogen largely stays intact;
  • The boron condenses into droplets as the plasma cools;
  • The droplets form small clusters as the temperature falls to a few thousand degrees;
  • The critical next step is the reaction of nitrogen with small clusters of boron molecules to form boron-nitrogen chains;
  • The chains grow longer by colliding with one another and fold into precursors of .

“During the high-temperature synthesis the density of small boron clusters is low,” Barsukov said. “This is the main impediment to large-scale production.”

The findings have opened a new chapter in BNNT nanomaterial synthesis. “After two years of work we have found the pathway,” Kaganovich said. “As boron condenses it forms big clusters that nitrogen doesn’t react with. But the process starts with small clusters that nitrogen reacts with and there is still a percentage of small clusters as the droplets grow larger,” he said.

“The beauty of this work,” he added, “is that since we had experts in plasma and fluid mechanics and we could go through all these processes together in an interdisciplinary group. Now we need to compare possible BNNT output from our model with experiments. That will be the next stage of modeling.”

More information:
Yuri Barsukov et al, Boron nitride nanotube precursor formation during high-temperature synthesis: kinetic and thermodynamic modelling, Nanotechnology (2021). DOI: 10.1088/1361-6528/ac1c20

Pathway to forerunner of rugged nanotubes that could lead to widespread industrial fabrication (2021, September 16)
retrieved 17 September 2021
from https://phys.org/news/2021-09-pathway-forerunner-rugged-nanotubes-widespread.html

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Hexbyte Glen Cove Biosynthesis pathway of a new DNA nucleobase elucidated thumbnail

Hexbyte Glen Cove Biosynthesis pathway of a new DNA nucleobase elucidated

Hexbyte Glen Cove

A : T, G : C and Z : T bonds. Credit: Pasteur Institute

DNA is composed of nucleobases represented by the letters A, T, G and C. They form the basis of the genetic code and are present in all living beings. But in a bacteriophage, another base, represented by the letter Z, exists. This exception, the only one observed to date, has long remained a mystery. Scientists from the Institut Pasteur and the CNRS, in collaboration with the CEA, have now elucidated the biosynthesis pathway of this base. This work has been published in the April 30th, 2021 issue of Science.

DNA, or deoxyribonucleic acid, is a molecule that serves as the medium for storing genetic information in all living organisms. It is a characterized by alternating purine nucleobases (adenine and guanine) and pyrimidine nucleobases (cytidine and deoxycytidine). The bases of each DNA strand are located at the center of the helix and are bonded together, thereby linking the two DNA strands: adenine forms two with thymine (A-T), and guanine forms three hydrogen bonds with cytosine (G-C). This applies to all living beings, with one exception.

Cyanophage S-2L, an exception to conventional genetics

Cyanophage S-2L is a bacteriophage, in other words a virus that infects bacteria. In this phage, adenine is completely replaced by another base, 2-aminoadenine (represented by the letter Z). The latter forms three hydrogen bonds with thymine (Z-T), instead of the usual two bonds between adenine and thymine. This higher number of bonds increases the stability of the DNA at high temperatures and changes its conformation, meaning that the DNA is less well recognized by proteins and small molecules

2-aminoadenine biosynthesis pathway elucidated

Since it was discovered in 1977, cyanophage S-2L has been the only known exception, and the biosynthesis pathway of 2-aminoadenine has remained unknown. Scientists from the Institut Pasteur and the CNRS, in collaboration with the CEA, recently elucidated this biosynthesis pathway and demonstrated its enzymatic origins. They achieved this by identifying a homolog of the known enzyme succinoadenylate synthase (PurA) in the genome of cyanophage S-2L. A phylogenetic analysis of this enzyme family revealed a link between the homolog, known as PurZ, and the PurA enzyme in archaea. This indicates that the homolog is an ancient enzyme that probably conferred an evolutionary advantage. The research was carried out using the Institut Pasteur’s Crystallography Platform.

The new Z-T base pair and the discovery of the biosynthesis pathway show that new bases can be enzymatically incorporated into genetic material. This increases the number of coding bases in DNA, paving the way for the development of synthetic genetic biopolymers.

More information:
Dona Sleiman et al, A third purine biosynthetic pathway encoded by aminoadenine-based viral DNA genomes, Science (2021). DOI: 10.1126/science.abe6494

Biosynthesis pathway of a new DNA nucleobase elucidated (2021, July 9)
retrieved 11 July 2021
from https://phys.org/news/2021-07-biosynthesis-pathway-dna-nucleobase-elucidated.html

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