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.

Two recent developments highlight the increasing role of nuclear technologies in agriculture and food. First, in her budget speech on July 23, Finance Minister Nirmala Sitharaman said the government would provide financial support for 50 multi-product food irradiation facilities. 

Second, the International Atomic Energy Agency (IAEA) organised the IAEA Scientific Forum ‘Atoms4Food’ in September. Speakers from different countries described how nuclear technologies were being used in agriculture and food production back home. 

From India, Satyendra Gautam, Head, Food Technologies Division, Bhabha Atomic Research Centre (BARC), told the audience that BARC had developed 62 improved varieties in 12 different crops, and the country boasts two major irradiation facilities at Vashi and Nashik respectively. 

Most participants spoke in the same vein — the Malaysian representative about rice and the Jamaican about ginger, for example. 

When people talk of nuclear technologies in agriculture and food production, it is always about irradiation. Irradiation for ‘radiation-induced mutagenesis’, or the use of radiation to bring about desired characteristic changes at the gene, chromosome or DNA level. Or irradiation used to kill microbes that cause rotting and thereby extend the shelf life of agricultural produce. 

However, there are many more nuclear technologies out there waiting to be used in agriculture. 

Here are some examples of nuclear technologies that can be deployed in agriculture to ensure food security: 

Fallout radionuclide (FRN) technique: You can tell the occurrence and extent of soil erosion by analysing radionuclides. A nuclide is a specific isotope of an element (example Cesium-137); a radionuclide is the nuclide of a radioactive element. 

Radionuclides bind themselves to the soil and move with the soil. By taking soil samples at different locations and depths, scientists can measure the concentration of these radionuclides. 

Areas with high radionuclide levels indicate soil accumulation while areas with lower concentrations suggest soil erosion. FRN technique “offers a distinct opportunity to quantify soil erosion rate and understand erosion processes in the landscape in a comprehensive manner,” say Suresh Kumar et al, authors of a paper on using FRN for measuring soil erosion in the Himalayas. 

The authors, from the Indian Institute of Remote Sensing and the Indian Institute of Soil and Water Conservation, both in Dehradun, say the FRN technique “offers a reliable, cost-effective, and long-term measurement of soil erosion rates, making it a valuable tool for soil ecosystem management.” 

Cosmic-ray neutron sensor (CRNS) technology: It is known that some farmers bury sensors in the soil; these sensors continually transmit moisture levels in the soil, helping the farmer decide when and how much to irrigate. 

CRNS is a simpler alternative to determine the moisture content over a vast field, say, 20 hectares. Cosmic rays are high-energy particles that roam in space. Some of them enter the earth’s atmosphere, where they collide with atoms of atmospheric gases. These collisions generate secondary particles, including fast-moving neutrons. 

These neutrons scatter and penetrate the soil, where they interact with the hydrogen atoms in the soil moisture. Since moist soil absorbs more neutrons, the number of neutrons that escape back into the atmosphere is less. Dry soil reflects more. The cosmic ray neutron sensor detects the number of neutrons, by which you can tell the soil moisture levels. 

Though CRNS is said to be mainly used to measure soil moisture content over a large area, a group of Chinese scientists have suggested in a paper that it is possible to also use it for detecting moisture at desired points, such as roots. This is done by adjusting the sensor’s placement and footprint. 

Radioimmunoassay (RIA) technology: RIA can be gainfully employed in animal reproduction. This is a technique in which a radioactively labelled version of a target molecule, such as a hormone, is injected into the animal. An antibody can bind to either the natural or the radioactively labelled version. RIA can be used to monitor critical reproductive hormones, such as progesterone, estrogen and luteinising hormones. 

By detecting hormonal changes in animals, RIA can help in determining the optimal time for artificial insemination. The technique can also help improve fertility by identifying reproductive issues in animals, such as irregular hormone levels. 

Sterile insect technique (SIT): This is an ingenious way of controlling pests. SIT involves mass rearing of the target insect, sterilising it to kill the reproductive cells and releasing it into the wild, where it competes with the natural insects for mating. When they mate, they do not produce offspring. The insect population goes down.

Other uses of nuclear technologies in agriculture include nitrogen-15 used to measure nitrogen fixation in roots and avoid unnecessary use of fertilizers; isotropic tracing techniques for crop nutrition and water management; and nuclear methods of analysing food authenticity and verifying geographic origins. 

While many of these techniques are proven, they have not come into widespread use — certainly not in India — yet.

It’s 2 am and you’re still awake. Your surgery is coming up soon, and you have questions. What if there are complications? How long will recovery take? And more. 

More than 70 per cent of patients experience anxiety before surgery, studies show, and they seek reliable information on what lies ahead. But anecdotal experiences and online information can be confusing.

Expert-in-the-loop (EITL) chatbots offer a potential solution. They use large language models (LLM) and curated knowledge to respond to queries. They also have an additional step of verification and correction by human experts. The bot can selectively update its knowledge base using expert insights.

In the healthcare industry, EITL chatbots can provide patients on-demand access to doctor-verified medical information, thereby easing the load on physicians. 

A team at Microsoft Research Lab India, led by Mohit Jain, partnered with doctors and patient coordinators at Sankara Eye Hospital, Bengaluru, to create CataractBot, an EITL chatbot that can answer queries about cataract surgery. 

The team conducted several interviews to understand common questions and misconceptions about cataract surgery. The bot’s knowledge base drew from resources such as hospital procedures, treatment guidelines, and pre- and post-surgery guidelines. However, it did not include patient data to ensure privacy. 

CataractBot was developed in nine months, after an iterative process of feedback and refinement. 

Design decisions

A major challenge for an EITL chatbot is in catering to users from diverse linguistic, educational, and technical backgrounds. 

For instance, cataract surgery patients are usually above 60 years old. The bot must, therefore, take into account their comfort level with technology usage. So it uses a chat window on WhatsApp. Patients and their attendants can use text, speech, or tap-based interactions with the bot in five available languages. Responses are in text and audio formats to ensure literacy levels and language proficiency are no bar. 

EITL chatbots need expert input for verification. This can be challenging given time constraints. Intelligent design can mitigate this challenge. For instance, doctors on the CataractBot expert panel receive a one-click verification prompt to confirm the accuracy of an answer. Where needed, doctors can provide informal text feedback without editing the original response. 

Streamlined workflows

EITL chatbots can streamline workflows for experts, who merely need to verify LLM-generated responses instead of answering common inquiries directly. Over time, the bot’s ability to provide accurate answers is expected to improve. 

Dr Kaushik Murali, a paediatric ophthalmologist at Sankara Eye Hospital who was involved in developing CataractBot, says patients often have trouble remembering what the doctor says. They can unhesitatingly repeat their queries to the chatbot multiple times, freeing up doctors to focus on more complex issues during in-person visits.

Dr R Sowmya, another paediatric ophthalmologist, says, “It offers privacy to me and the patient… and encourages them to ask ‘silly’ questions that they may hesitate to ask otherwise.”

A new method of introducing controlled defects in MOF-based supercapacitors through laser irradiation, can help enhance performance of existing energy storage technologies.

In recent years, several methods have been investigated for creating defects, such as thermal annealing, chemical exposure, high-energy ball milling, e-beam and chemical vapour deposition. However, the extent of defects could not be controlled in the materials using these methods. Traditional methods lack the precision needed for fine-tuning of defects.

In order to enhance the activity of the pristine MOF (Metal Organic Framework) without transforming it into other materials or creating a composite out of it, scientists at the Institute of Nano Science and Technology (INST), Mohali, carefully adjusted laser power to systematically regulate defects and porosity resulting in a significant increase in the electrode’s surface area and activity, says a press release.

By precise tuning of the laser powers, Prof Vivek Bagchi and his team controlled the defects and porosity in pristine CuZn-BTC MOF without changing its crystal structure.

The novelty of this technique is that the crystallinity of the MOF material is mostly preserved; however, the laser irradiation enhances the activity of the material.

Scientists from Jawaharlal Nehru Centre For Advanced Scientific Research (JNCASR) and National Bureau of Agricultural Insect Resources (NBAIR), Bengaluru, have jointly developed a sustainable pheromone dispenser with a controlled release rate which could act as an innovative solution to reduce the costs of pest control and management.

Sustainable organic pheromone dispensers are not a new concept. In fact, polymer membrane or polypropylene tube dispensers that release pheromones already dominate the market. The released pheromones alter the behaviour of the target insect species and attract them to sticky traps. Their main drawback, however, is that the rate at which the pheromones are released into the air is not stable. These traps need to be checked and replaced frequently, which drives up costs and increases the amount of manual labour required.

To address this issue, the scientists have come up with a mesoporous silica matrix for their dispenser. This material has an ordered structure with many tiny pores, which allows pheromone molecules to be easily adsorbed and retained uniformly. Not only does mesoporous silica enable a higher holding capacity than other commercial materials, but it also releases the stored pheromone in a much more stable manner that is independent of external conditions, such as field temperature.

Using lures equipped with the proposed pheromone dispenser carries many advantages. First, thanks to the lower and more stable release rate of the loaded pheromone, the intervals between replacements are longer, thereby reducing the farmers’ workload. On top of this, the dispensers can be loaded with a more conservative amount of pheromone, as the condition-independent release rate will ensure they do not run out prematurely.