Cyber Surakshit Bharat
8-May-2023: NeGD organises 36th CISO Deep-Dive Training Programme Under Cyber Surakshit Bharat
National e-Governance Division (NeGD), under its Capacity Building scheme, organised 36th CISO Deep-Dive training programme from 8th-12th May 2023 with 24 participants from Central Line Ministries and States/UTs at Indian Institute of Public Administration, New Delhi.
The five-day intensive training programme is designed for designated CISOs from Central and State/UT Governments, subordinate agencies/PSUs, including public sector banks and insurance companies, technical wings of police and security forces, CTOs and members of technical/PMU teams; also, officers responsible to observe security of IT systems in their respective organisations.
Metavalent bonding
3-May-2023: Metavalent chemical bond holds key to enhance the thermoelectric performance in quantum materials
Metavalent bonding—a new type of chemical bonding in solids, can be used to tailor the thermoelectric performance in quantum materials and efficiently convert waste heat to electricity, which could show a new direction for the country’s newly launched Quantum Mission.
Generating electricity from waste heat holds an exciting prospect for green energy production. Finding high-performance thermoelectric materials for this purpose requires materials with a magical recipe of properties that can conduct electricity like a metal, heat like a glass, and exhibits the Seebeck coefficient like a semiconductor.
The performance of a thermoelectric material is evaluated based on a dimensionless index related to electrical resistivity, Seebeck coefficient, and thermal conductivity called zT. The higher the zT, the higher is the efficiency. Increasing zT is extremely challenging due to the contradicting interdependences between the material constants that constitute zT, like the electrical and thermal conductivity, Seebeck coefficient, etc. Hence this index needs to be optimised.
To realize this challenging goal, Prof. Kanishka Biswas and his Integrated Ph.D. student Ivy Maria from JNCASR, Bengaluru, an autonomous institute of the Department of Science and Technology (DST), turned to the biggest tool in the kit of chemists- the chemical bonding in a solid. They needed a chemical bond that has properties of both the bonding present in metals (for good electrical conductivity) as well as those found in glasses (for low thermal conductivity), demanding for fine tuning between electron localization (covalency) and delocalization (metallicity). Such a bonding synergy is found in materials with a unique type of bonding called metavalent bonding. Metavalent bonds are multicentric soft bonds with less than 2e- shared between the bonding atoms, defying the classical octet rule in chemistry. But, at this juncture, they encountered an inverse design problem -- knowing the bonding/properties can they predict the compound(s) that can exhibit them?
Their search for materials with excellent electrical properties drew them to quantum materials such as topological insulators --- an exotic family of compounds that have conducting surface states but insulating bulk states. They chose TlBiSe2- a renowned topological insulator, for investigation. One of the reasons behind choosing this was that the material showed lattice shearing due to dual lone pair-induced local distortion mediated by metavalent bonding. They have analysed the local distortion by synchrotron X-ray pair distribution function experiment done in Petra-III, DESY, Germany, with the support of the DST Synchrotron support program.
An analogy to understand local distortion preserving the average crystal structure is a classroom of seated row/column-wise students. From the teacher’s view (average structure), they appear to be sitting in a perfect straight line, but if we look from an individual student’s view (local structure), we will see that the students in front/back are not exactly ahead/behind but slightly shifted. Atoms in a locally distorted crystal show this behaviour wherein their positions are not perfectly ordered as expected but are slightly distorted.
Through collaborative work with other authors, Ms. Raagya Arora, Dr. Moinak Dutta, Dr. Subhajit Roychowdhury, and Prof. Umesh Waghmare from JNCASR; they confirmed that TlBiSe2 indeed demonstrates metavalent bonding. The distorted structures have energies very close to that of the undistorted structure of TlBiSe2, and at room temperature, the compound can easily shuttle between the various energetically accessible configurations.
Thus, TlBiSe2 possesses a degenerate manifold of ground states, facilitating a fundamentally new way of intrinsically scattering phonons (quasi-particles that carry heat in a solid) via lattice shearing availed by the underlying metavalent bonding to realize low thermal conductivity. Validating the chemical bonding guided strategy, TlBiSe2 showed a zT of around 0.8, which is the highest reported to date amongst n-type thallium chalcogenides.
Their work provides fundamental insights on how novel chemical bonding can be used to optimize thermoelectric performance in quantum material and how, by rational chemical designing, intriguing emergent properties can be realized in quantum materials towards which India’s Quantum Mission is working. The work has recently been published in Journal of American Chemical Society (JACS).
3D Printing
3-May-2023: Smart gel-based sheet can form 3D Printed Conduit helping non-invasive nerve repair
A new smart gel-based sheet using three-dimensional (3D) printing technology that can self-roll into a tube during surgery to form a nerve conduit could help reduce the complexity of surgeries and aid rapid healing of nerve injuries.
The gold standard for the treatment of peripheral nerve injuries is still autografts. Bioresorbable polymer-based conduits are being explored for clinical use as alternatives. But these treatment strategies suffer from several limitations, such as donor site morbidity in the case of autografts and the necessity for sutures that demand highly skilled microsurgeries, and additional complications posed by sutures.
These clinical shortcomings motivated researchers at the Indian Institute of Science (IISc) in Bengaluru to design a smart gel-based sheet using three-dimensional (3D) printing technology that can self-roll into a tube during surgery to form a nerve conduit. In 3D printing, a virtual model of the part is created using design software, and the part is then fabricated using a 3D printer by layer-upon-layer deposition of the material. 3D printed parts can further undergo a shape change on demand upon activation after fabrication. Such technologies are now widely known as four-dimensional (4D) printing, where time is the extra dimension.
In a recent study, the team at IISc, led by Professor Kaushik Chatterjee, engineered a bilayered gel sheet by 3D printing in pre-defined patterns from two gels. The gel formulations were selected to swell differently. When the dried gel sheet was immersed in water, it rapidly swelled and curled into a tube. The folding behavior and final shape of the gel could be programmed to generate tubes of desired dimensions, which could be predicted by computational modeling. The gel sheets were then coated with thin nanometer-scale fibers to enable the body’s cells to adhere to the gel sheet.
The team at IISc worked closely with researchers at the Indian Institute of Technology at Roorkee and Maharishi Markandeshwar University to test the 4D printed conduits for repairing and regenerating a 2 mm gap in the sciatic nerve of rats. The shape-morphing sheets were placed under the defect region of the nerve and stimulated to wrap the defect site to form a conduit around the nerve without suturing. The nerve ends could grow through the implanted conduit. There was a remarkable improvement in nerve regeneration measured up to 45 days in the rats when the 4D printed nerve conduits were used. The team consisting of Akshat Joshi, Saswat Choudhury, Vageesh Singh Baghel, Souvik Ghosh, Sumeet Gupta, Debrupa Lahiri, G.K. Ananthasuresh, Kaushik Chatterjee reported its findings in a paper published in Advanced Healthcare Materials. This work was supported by the Science and Engineering Research Board (SERB), a statutory body of the Department of Science and Technology, under the Intensification of Research in High Priority Areas (IRHPA) special call on 3D Bioprinting.
Such 4D-printed parts have not been used in the clinic as yet. But such emerging technologies could pave the way for a new generation of medical devices that surgeons can deploy during surgery to heal nerves and many other tissues in coming years. They can offer benefits such as reduced complexity of surgeries, deployment by minimally-invasive procedures, and faster healing.