Diamonds are a UV photodetector’s best friend


Bhathwari Technologies Pvt Ltd, a company in Surat that synthesises diamonds using the chemical vapour deposition (CVD) technique, recently signed a memorandum of understanding with IIT-Delhi for the development of diamond-based deep ultraviolet (UV) photodetectors for the first time in India. 

A photodetector senses light and converts it into an electrical signal. When UV light hits the photodetector’s surface, it generates a small current or voltage, which can be measured. Diamond-based photodetectors can sense deep UV light because of diamond’s high sensitivity to UV photons, and they are resistant to damage from harsh environmental conditions (such as radiation and heat). 

Deep UV photodetectors find application in areas such as UV imaging, secure communication, biological detection, military detection, and so on. The advantage in these photodetectors is their highly selective photo response in the deep UV region, and high efficiency at room and higher temperatures. 

Under the collaboration, Bhathwari Technologies will provide high-quality CVD-grown diamond samples to IIT-Delhi. The researchers involved in the design and development of the UV photodetectors are led by Prof Rajendra Singh from the physics department. 

Prof Singh’s research group has a long-standing experience in developing UV and deep UV photodetector technology based on wide bandgap semiconductor materials such as gallium nitride, aluminium gallium nitride, aluminium nitride, and gallium oxide. 

Industry-academia tie-up

Bakul Bhai Limbasiya, Chairman of Bhathwari Technologies, says, “We had synthesised the first lab-grown diamond (LGD) in India in 2001 and have since been actively engaged in developing the CVD reactors and related technology for LGDs.” 

Diamonds have an ultra-wide bandgap — namely the energy difference between the valence band, where electrons are bound to the atoms, and the conduction band, where electrons are free to move and therefore conduct electricity. 

A material with a wide bandgap, such as diamond, can withstand very high voltages and temperature. This makes it ideal for high-performance electronics. 

Diamond-based photodetectors are particularly responsive to deep UV radiation — they can, therefore, sense even low levels of UV radiation. 

Furthermore, diamond’s structural properties allow for high-signal accuracy with minimal background ‘noise’. 

As such, diamond-based deep UV photodetectors can be used to monitor ozone layers, for instance. 

They are suitable for defence and space applications, says a press release from IIT-Delhi.





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Meta’s mega gift to material science 


Discovery of new materials with desired properties is not easy, ask any alchemist. You must take two materials that have the properties that you want and, like making a baby, you must see how to combine them to get exactly the offspring that you want. 

Meta (formerly, Facebook), often bashed for cashing-in on data, has now given a meta gift to mankind: tomes of data — for research into functional (meta) materials. 

The global giant has just released copious amounts of data about behaviour of materials at the atomic level, under its Open Materials 2024 (OMat24) initiative, for free. 

This data can help scientists combine different materials with different desired properties to create something new. Examples of functional materials that can tackle climate change include new catalysts for renewable energy storage, carbon neutral fuels, new sorbents for direct air capture, etc. 

Creating such materials is somewhat similar to discovering a drug molecule for disease by trying out different combinations of molecules or making a dish of desired taste, texture and flavour from millions of ingredients. 

Traditionally, making meta materials involved playing trial-and-error with millions of data points from thousands of materials. But now, there is Artificial Intelligence (AI), which can deliver the goods, however, AI is data hungry.  

Meta has provided this food for AI. The OMat24 dataset is a collection of data generated from simulations and calculations on different inorganic materials. This dataset contains information on 118 million atomic structures, whichhas information on three parameters — total energy (the overall energy of the material’s structure), forces (acting on each atom) and cell stress (indicating how the material could deform under certain conditions.) All this was calculated using ‘density functional theory’, a quantum mechanics-based method for predicting material properties . 

“The search space of possible materials is enormous and remains a significant challenge for both computational and experimental approaches to material science,” says a yet-to-be peer-reviewed paper by scientists at Meta’s Fundamental AI Research (FAIR) group. “Identifying promising candidates through computational screening with machine learning models offers the potential to dramatically increase the search space and the rate of experimental discovery,” says the paper, written by Luis Borroso-Luque et al. 

FAIR scientists took over 400 million core-hours of computing to get the data of 118 million structures labelled with total energy, forces and cell stress. (One CPU core used for one hour is one core-hour.) These parameters give an idea of the stability of materials under given conditions. 

Now that there is data on over 118 million atomic structures, one can train an AI model to come up with the best combination of any of them for a desired material. 





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India’s renewable energy capacity crosses 200-GW mark


The total renewable energy-based electricity generation capacity (including small and large hydro, biomass and co-generation and waste-to-energy) in India crossed the 200 GW-mark in September, to reach 201,457.91 MW. Solar (90,762 MW) and wind (47,363 MW) accounted for the bulk of it. If you add 8,180 MW of nuclear capacity to this, the country’s total non-fossil fuel-based power capacity stands at 46.3 per cent of the total installed electricity generation capacity. Rajasthan (31.5 GW), Gujarat (28.3 GW), Tamil Nadu (23.7 GW) and Karnataka (22.3 GW), are the top four states in renewable energy capacity, according to data provided by the Central Electricity Authority.

Golden brainstorming

The Central Electricity Authority will be entering its 50th year tomorrow. The body, whose remit is to provide technical support to all stakeholders, intends to kick-start its Golden Jubilee celebrations, by holding a ‘Brainstorming session on Indian Power Sector Scenario by 2047’, which the Union Power Minister, Manohar Lal Khattar, will inaugurate.

Some of the topics for the brainstorming sessions are: financing energy transition by 2047, building a modern, resilient and future-ready transmission system by 2047, capacity planning and regulatory framework for renewable energy by 2047, scaling up of hydro-power and harnessing PSP potential by 2047and the role of green hydrogen in India’s Net Zero future vision by 2047.

Module glut 

By the end of 2024, the world will have a solar module manufacturing capacity of 1,100 GW (India has 67 GW and 48 GW under construction).

The International Energy Agency notes that there is a glut in the module market. 

Module prices have more than halved since early 2023, the agency says in its latest report on the renewable energy sector. 

“The challenging market conditions have resulted in the cancellation of about 300 GW of polysilicon and 200 GW of wafer manufacturing capacity projects, valued at approximately $25 billion,” the report says.

RE projects hurt by grid-ache

Renewable energy projects globally are increasing but not quite on the trajectory to meet the ambition of “tripling of global renewable energy capacity by 2030” — from 2022. The goal implies global RE capacity to be 11,000 GW by 2030. The IEA report on renewable energy finds that current trends would take the global capacity to 9,760 GW, or 2.7 times increase from 2022.

But there is another problem: grid. Investments in grid are not in line with the need. Total global wind, solar PV and hydropower capacity in advanced development stages waiting for grid connections has increased from around 1,500 GW in 2023 to 1,650 GW in July 2024, the IEA report says.





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Nano road safety sensor


A prototype of a road safety sensor that can be implanted at high-risk and accident-prone curves has been developed from a new polymer nanocomposite with pressure sensing and energy harvesting properties. 

Researchers from the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, have developed the polymer nanocomposite and used it to develop a prototype of a road safety sensor. 

The prototype may be implanted in a movable ramp and secured to the road just 100 metres before the high-risk turning points. 

Thus, any vehicle approaching from the opposite side will see the signal on a screen and be alerted. This prototype works on the principle of piezoelectric effect, so it can generate energy that can be stored and used to power electronic gadgets as well. 

The novel polymer nanocomposite used in the prototype has been made out of transition metal dichalcogenide. 

The scientists — Ankur Verma, Dr Arjun Hari Madhu, and Dr Subash Cherumannil Karumuthil — synthesised vanadium disulphide with a high surface charge, which has the ability to enhance the piezoelectric characteristics of polymers. 

Polymer nanocomposite films were prepared by integrating nanoparticles in various concentrations into a well-known piezoelectric polymer, poly (vinylidene difluoride). 

Further, they investigated how the surface charge of nanoparticles will affect the piezoelectric properties of the polymer nanocomposite. 

In addition, a laboratory-scale demonstration of a road safety sensor and smart door was established, with the prototype as a pressure sensor.

New material for nanodevices

A breakthrough in understanding the process of controlling the assembly of tiny molecular units into complex structures holds promise for creating new materials that could revolutionise industries like electronics, healthcare, and beyond. 

Supramolecular self-assembly is a process where small molecules spontaneously organise into larger, well-defined structures without external direction. Understanding this process is crucial for creating new organic materials that can be used to develop nanodevices — tiny machines useful in performing specific tasks at the molecular level, such as drug delivery to specific parts of the body. 

A group of researchers at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, in collaboration with researchers from the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bengaluru, explored the self-assembly behaviour of specific molecules called ‘chiral amphiphilic naphthalene diimide derivatives’. They experimented with two different methods of assembling these molecules — solution phase assembly and air-water interface assembly. 

The former involved the assembling of molecules in a liquid solution, leading to the formation of spherical nanoparticles. These tiny particles displayed unique optical properties, such as strong mirror-imaged circular dichroism signals, which are important for materials that interact with light in precise ways. 

The air-water interface assembly involved assembling molecules at the boundary between air and water, which the researchers also tested. At the air-water interface, instead of forming spherical nanoparticles, the molecules arranged themselves into flat, two-dimensional layers with irregular edges. Interestingly, these layers did not exhibit the same optical properties as the solution-assembled nanoparticles, indicating that the environment in which molecules assemble plays a critical role in determining their final structure and properties.





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Neanderthals and humans: A love story


Neanderthals roamed the earth between 4,00,000 and 40,000 years ago. After being around for over 3,50,000 years, they suddenly disappeared, and nobody knows why. However, before they disappeared there was a time their existence overlapped that of early human beings. We still have 2-3 per cent of Neanderthal DNA in us. There is no evidence of a conflict between Neanderthals and Homo sapiens, even though both went in for the same resources. On the other hand, there is evidence that members of the two species interbred. Even the other archaic human beings, the Denisovans, interbred with human beings. 

A group of scientists led by Saman H Guran, a research associate at the Stiftung Neanderthal Museum in Mettmann, Germany, recently studied 20 sites with modern human remains and another 20 with Neanderthal to find out where they may have lived. Their computer modelling considered factors like precipitation, weather and location of caves. 

The researchers arrived at the conclusion that the best area where the two species had contact and interbred, between 1,20,000 and 1,80,000 years ago, was the Zagros mountain range in present-day Iran, Iraq and southeastern Turkey. 

A region today far removed from the seeming peace and accommodation of aeons ago.





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4D-printed blood vessels


3D printing is well understood and ubiquitous by now but not many may know of 4D printing. 

To put it simply, 4D printing is the process by which a 3D-printed object transforms itself into another structure, under the influence of external stimuli such as light, temperature, water, a magnetic field or chemicals. 

You can, for example, print a flat object with some smart material and program it to fold into a 3D shape when, say, exposed to water. This process has been used by a team of scientists at the Department of Materials Engineering and Bioengineering, Indian Institute of Science, Bengaluru, to make artificial blood vessels. 

The team, led by Dr Kaushik Chatterjee and Dr Amit Nain, developed a nanoengineered hydrogel ink and printed it on sheets. (Hydrogels are gel material from which liquid has been sucked out.) These sheets self-fold into tubular structures when immersed in a calcium chloride solution. 

The team coated the surface of the vessels with gelatin so that cells may stick to it, says an article in IISc’s in-house publication Kernel. 

It says the gel formulation was “chemically modified prior to 3D printing” to give the printed structures anti-oxidative and anti-inflammatory properties. It will also help deal with clotting. 

“Current grafts require additional surgeries, carry risks of rejection and disease transmission, and are prone to clotting and other complications. These artificial blood vessels are a step forward in solving these challenges,” the article says. 

Building organs 

4D-printed blood vessels are crucial for tissue engineering, which, in turn, is a vital part of regenerating organs. 

These blood vessels act as a scaffold for seed cells to grow on; they also supply blood to the growing tissue. 

While there are synthetic blood vessels made of materials such as polytetrafluoroethylene and polyurethane, they are not “dynamic”, namely they cannot adapt to the changing environment. 

But 4D-printed blood vessels can expand, contract or grow in response to biological cues such as changes in blood pressure. This adaptability enables engineered tissues to grow and function better. 

Further, tissue engineering essentially involves culturing harvested cells, for which they need a scaffold — the framework for cells to adhere to and grow into the desired organ. 

4D-printed blood vessels can self-assemble into complex, interconnected vascular networks after being implanted, which enhances the efficiency of tissue vascularisation. And, of course, the blood vessels also perform their primary job of keeping the tissue cells well supplied with blood. 

“The artificial development of a vascular system, specifically the blood vessel network, is considered the holy grail of tissue engineering,” write Daphene Marques Solis and Aleksander Czekanski of York University, Canada, in a 2022 scientific paper. 

Though tissue engineering has advanced, the production of blood vessels “remains a challenge that inhibits the production of organs and tissues thicker than 200 m,” they say, adding that “ascularization is a bottleneck in the evolution of tissue engineering”. 

4D-printed blood vessels promise to remove this bottleneck.





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