Subject: Basic Sciences

Why in the News?

The 2025 Nobel Prize in Chemistry has been awarded to Richard Robson, Susumu Kitagawa, and Omar Yaghi for pioneering the creation of metal–organic frameworks (MOFs).

What are Metal–Organic Frameworks (MOFs)?

• Overview: They are crystalline materials composed of metal ions linked by organic molecules, forming a three-dimensional porous network capable of selectively trapping and storing gases, vapours, or liquids.
• Structure: Metal ions serve as nodes or connectors, while organic ligands (carbon-based linkers) create scaffold-like frameworks with very high surface area and controllable pore size.
• Porosity: MOFs possess some of the highest porosity among solids, often exceeding 7,000 square metres per gram, enabling the storage of large volumes of gases within minimal material.
• Flexibility: Organic linkers can be chemically modified, allowing custom design for specific interactions, such as selective gas capture or catalysis.
• Thermal and Chemical Stability: Advanced MOFs remain stable up to 300–400°C and can withstand diverse chemical environments, suitable for industrial and environmental use.
• Bonding Principle: Based on coordination chemistry, MOFs combine metal rigidity with organic flexibility, enabling precise control over molecular architecture.
• Functionality: Their open channels permit easy adsorption and desorption, making MOFs reusable, durable, and efficient for a range of scientific and industrial applications.

Applications of MOFs:

• Water Harvesting: Capture moisture from arid air and release it upon heating — enabling portable water generation in desert regions.
• Carbon Capture: Their selective pores allow efficient CO₂ capture and storage, aiding climate change mitigation.
• Hydrogen and Methane Storage: Act as solid sponges essential for fuel cells and clean energy systems.
• Pollutant Filtration: Remove PFAS (Per- and Polyfluoroalkyl Substances), heavy metals, and organic contaminants from water sources.
• Food Preservation: Absorb ethylene gas emitted by fruits, slowing ripening and extending shelf life.
• Catalysis and Sensing: Serve as heterogeneous catalysts and chemical sensors for trace-level detection in industrial settings.
• Clean Energy Systems: Integrated into batteries, fuel cells, and supercapacitors for energy storage due to high conductivity and surface area.

Scientific Development:

• Richard Robson (University of Melbourne, 1970s): He pioneered the idea of linking metal atoms and ligands into extended frameworks, though early models were fragile.
• Susumu Kitagawa (Kyoto University): Built porous coordination polymers, the first to demonstrate that gases could diffuse through molecular cavities—a defining MOF feature.
• Omar Yaghi (University of California, Berkeley, 1990s): Created robust, heat-resistant MOFs, standardised synthesis techniques, and coined the term “Metal–Organic Framework” in a 1995 Nature paper.
  • Breakthrough Achievement: Yaghi’s team designed copper- and cobalt-based MOFs stable up to 350°C, capable of hosting guest molecules without collapse.

Why in the News?

The 2025 Nobel Prize in Physics has been awarded to John Clarke, Michel Devoret, and John Martinis for their discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit.

Discovery of Macroscopic Quantum Effects:

• Essence of the Discovery: John Clarke, Michel Devoret, and John Martinis proved that quantum effects—tunnelling and energy quantisation—can occur in macroscopic electrical circuits, not just in atoms or particles.
• Experiments (UC Berkeley, 1984–85): Demonstrated that superconducting circuits, visible to the naked eye, act as quantum systems when isolated from external disturbances.
• Observed Phenomena:
  • Macroscopic Quantum Tunnelling: Electric current “jumps” through an insulating barrier even when classical physics predicts no flow.
  • Energy Quantisation: The circuit holds only discrete energy levels, behaving like an artificial atom that exchanges energy in fixed quanta.
• Scientific Breakthrough: First experimental proof that quantum mechanics governs engineered large-scale systems, forming the foundation of quantum computing.

The Josephson Junction:

• Structure: Two superconductors separated by a thin insulating layer, allowing the passage of Cooper pairs paired electrons that move as a single quantum entity.
• Mechanism: Though insulators block current in classical systems, Cooper pairs tunnel through the barrier, producing a supercurrent without resistance.
• Key Berkeley Findings:
  • The phase difference across the junction behaved as a quantum variable, showing discrete energy states.
  • Spontaneous tunnelling of current produced measurable voltage, confirming macroscopic quantum tunnelling.
• Outcome: The Josephson junction became the first laboratory model of macroscopic quantum behaviour and the prototype for superconducting qubits used in today’s quantum computers.

Significance:

• Redefined Quantum Boundaries: Established that quantum laws are universal, applying from electrons to circuits of billions of atoms when quantum coherence is preserved.
• Foundation for Quantum Computing: Provided the conceptual basis for superconducting qubits, now central to Google, IBM, and TIFR quantum processors.
• Technological Impact: Enabled innovations in quantum sensors, precision metrology, and quantum communication through microwave-to-optical conversion.
• Philosophical Insight: Resolved the scale question of how large a system can remain quantum,  proving that superconducting isolation preserves coherence even at macroscopic levels.
• Legacy: Bridged the quantum–classical divide, converting a theoretical boundary into experimentally verified reality, launching the modern quantum technology era.

Why in the News?

For the first time, researchers at the Central University of Rajasthan (CUoR) have successfully grown wheat in arid land of western Rajasthan using desert soilification technology.

What is Desert Soilification Technology?

• Overview: It is an innovative biotechnological method that transforms barren desert sand into soil-like material capable of supporting agriculture.
• Technology: It uses bioformulations and polymers to bind loose sand particles, improve soil texture, and enable water retention.
• Utility: It is designed to combat desertification, enhance agricultural productivity in arid zones, and ensure sustainable land use.
• How does it work?
  • Polymer-based Bioformulation: Natural polymers and microbial formulations are applied to desert sand.
  • Cross-Linking of Sand Particles: Bio-polymers create a structural network, binding sand grains together into a soil-like matrix.
  • Water Retention: The cross-linked structure traps water, drastically reducing irrigation needs and preventing rapid percolation of water through sandy soil.
  • Microbial Boost: Introduced beneficial microbes stimulate plant growth, improve soil fertility, and enhance stress resistance of crops.
  • Soil-like Properties: The modified sand mimics fertile soil — enabling nutrient retention, microbial colonization, and sustainable cropping.

Key Features:

• Sand-to-Soil Conversion: Cross-links sand particles into a soil-like structure, creating porosity and root-holding capacity.
• Water Retention Efficiency: Increases moisture-holding ability of sand, thereby reducing irrigation requirements by 30–40%.
• Microbial Boost: Bioformulation stimulates beneficial soil microbes, enhancing nutrient cycling and crop stress resistance.
• Crop Versatility: Tested successfully with wheat, bajra, guar gum, chickpea, and is now being expanded to millets and green gram.
• Low Input Agriculture: Reduces number of irrigation cycles (3–4 vs 5–6 in normal wheat farming).
• Climate Resilience: Provides a sustainable model for food production in water-stressed and desertified regions.
• Scalability: Can be replicated in other arid ecosystems beyond Rajasthan (potential use in Middle East, Africa).

Why in the News?

Iran’s supreme leader recently said Tehran has limited uranium enrichment to 60% U-235 and will not pursue further enrichment to ~90% (weapons grade).

About Uranium Enrichment:

• What is it: The process of increasing the proportion of U-235 isotope in uranium samples. Natural uranium has only 0.7% U-235, while the rest is mostly U-238.
• Types of Enrichment:
  • Low-Enriched Uranium (3–5%): Used in civilian nuclear power reactors.
  • Highly Enriched Uranium (HEU, >20%): At 90%+ enrichment, uranium becomes weapons-grade, usable for efficient nuclear weapons.
• Methods: Physical separation methods such as gas centrifuges, requiring advanced infrastructure and technology.
• Implications:
  • Low enrichment: Controlled power generation.
  • High enrichment: Proliferation risks, shorter path to nuclear weapons capability.

Controversy about Iran’s Pursuit:

• Declared Program: Iran enriches uranium to 60% U-235, claiming peaceful purposes, but insists it will not pursue 90%+ enrichment.
• Global Concerns:
  • Civilian irrelevance: 60% has no reactor use, only shortens the “breakout time” to weapons-grade.
  • IAEA Monitoring: International Atomic Energy Agency reports show significant 60% stockpiles, heightening suspicion.
• Geopolitical Context:
  • Joint Comprehensive Plan of Action (2015) capped enrichment at 3.67% but collapsed after U.S. withdrawal in 2018.
  • Western governments see 60% enrichment as undermining trust, while Iran argues it is a deterrence and bargaining tool.
• Strategic Dimension: Keeps Iran on the nuclear threshold, enabling leverage in negotiations and projecting deterrence without overt weaponisation.

Why in the News?

Cold fusion reaction, once dismissed after failed 1989 claims, is back in discussion as US-based researchers report neutron production from their small “Thunderbird Reactor.”

What is Cold Fusion Reaction?

• Overview: A proposed way to achieve nuclear fusion at room temperature, unlike conventional fusion which needs extremely high heat (100 million °C or more).
• How it started: In 1989, two chemists, Martin Fleischmann and Stanley Pons, said their palladium-heavy water experiment created more heat than normal chemistry allows.
• Problem: Other scientists could not reproduce the result. No clear evidence of fusion products (like neutrons or helium) was found. The claim was dismissed, but the idea stayed alive.
• Why interest remains: If proven, cold fusion could provide limitless, clean, and cheap energy. Research in this area is now called Low-Energy Nuclear Reactions (LENR).

About the Thunderbird Reactor (2025)

• Inception: Scientists led by Curtis Berlinguette, University of British Columbia, published in Nature (Aug 2025).
• Why built: Not to make electricity, but to test if chemistry can affect nuclear reactions.
• How it works:
  • A plasma thruster shoots deuterium ions (a form of hydrogen) at a palladium metal target.
  • At the same time, an electrochemical cell pushes more deuterium into the palladium.
  • This builds up a very high density of deuterium inside the metal, making fusion more likely.
  • A neutron detector checks if fusion really happens.

Key Findings:

• Neutrons detected: When deuterium ions hit palladium, about 130–140 neutrons per second were observed (much higher than background levels).
• Electrolysis boost: Adding extra deuterium through electrolysis increased the neutron count further.
• Energy output: The reaction only produced a tiny amount of power (one-billionth of a watt) while consuming 15 watts of electricity. No net energy gain yet.

Why in the News?

The Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI) 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, Tamil Nadu, is scheduled to achieve criticality in March 2026 and reach full power generation by December 2026.

About India’s Prototype Fast Breeder Reactor (PFBR):

• Design began: 1980s as prototype for future 600 MWe FBRs.
• Timeline: Construction began in 2004, faced delays; cost escalated from ₹3,500 crore to ₹7,700 crore.
• Capacity: 500 MWe, sodium-cooled fast breeder reactor.
• Predecessors: It builds on India’s earlier reactors: KAMINI and Fast Breeder Test Reactor (FBTR).
• Technology: Completely indigenous, designed by Indira Gandhi Centre for Atomic Research (IGCAR).
• Fuel: Uranium-Plutonium mixed oxide (MOX); later stages to use Thorium-232 to breed fissile U-233.
• Burnup: 100 GWd/t, reactor life ~40 years.
• Coolant: 1,750 tonnes of liquid sodium; pool-type design with high thermal inertia.
• Construction agencies: Uranium-Plutonium mixed oxide (MOX) fuel fabricated by BARC Tarapur; reactor equipment by BHEL.
• Site: Kokkilamedu, near Kalpakkam (next to Madras Atomic Power Station).

Significance in India’s Nuclear Programme:

• PFBR is the second stage of India’s three-stage programme:
  • Stage 1: Pressurised Heavy Water Reactors (PHWRs) using natural uranium.
  • Stage 2: Fast Breeder Reactors producing plutonium and U-233 from thorium.
  • Stage 3: Thorium-based U-233 fuel cycle.
• Enables closed fuel cycle: recovery and recycling of fissile and fertile material from spent nuclear fuel (SNF).
• Enhances energy security by optimally utilising limited uranium and vast thorium reserves.
• Reduces radioactive waste through recycling.