Materials Connect

Coronavirus & materials science

RNA viruses have a high spontaneous mutation rate, which rarely leads to a viable virus. But when they do, the new virus might be transmissible to humans and not be recognized by our immune system. This is how the new coronavirus Covid-19 emerged, causing worldwide fear. Yet, many virologists, biologists, and medics are remaining calm and investigating a vaccine and treatment. As materials researchers, what could we do?

Schematics of the general structure of coronaviruses featuring spike proteins in the outer layer (credit: Nature Publishing group).

Materials science is multidisciplinary, and applies to many fields. Materials can be bio, electronic, dense, porous, passive, active, etc. As a consequence, materials science can play a role in many aspects in the fight against Covid-19, such as in the following areas:

• identification. To be able to elaborate an adequate response to the effects of the virus, it is necessary to know more about it, and in particular its structure. For example, knowing how the proteins forming the virus are folded and assembled in 3 dimensions can help to identify sites where a medical treatment could interact and stop the replication of the virus. Current microscopy methods such as cryogenic electron microscopy (cryo-EM)—where a nanoparticle, a protein assembly, or a virus is frozen and observed under many angles—has already been used to reconstruct with nanometric resolution the complex structure of coronaviruses. The folding of the spike proteins in the outer shell of a feline coronavirus was thus imaged.
• 
  

  3D electron density map recorded by cryo-EM of a spike protein of a coronavirus at 0.33 nm resolution and revealing a trimer structure with 18 nm diameter and 17 nm height (credit: PNAS).

• treatment. The acute symptoms of the coronavirus infection are similar to pneumonia, which is treated by injection of pain relievers and anti-inflammatory drugs. Encapsulating the treatment inside a protective and functional micrometric shell can help deliver the medicine to the infected area more effectively. For example, small microparticles loaded with the drugs were developed to be directly inhaled by the patient. Thanks to the small size of the microparticles, below 10 µm, it is possible to deliver high loads of drugs while reaching the small and deep capillaries in the lungs.
• diagnosis. Regular temperature checks have been implemented to identify infected patients, but other methods may be able to detect the presence of the virus before the appearance of the symptoms. In particular, lab-on-a-chip devices could be used to determine the early presence of the virus. Such chips are only 3 cm long and sequence the genome from infected cells using microfluidics and DNA-assays. It was developed earlier for other coronaviruses. Could such devices be implemented on our smartphones, like demonstrated earlier this year for early detection of malaria?
• prevention of spreading. Wearing a facemask or an N95 respirator is one way to avoid the propagation of droplets containing the virus from a person who carries it to another who is healthy. However, wearing masks is protective for only a couple of hours. Longer than this, the humidity from the breath widens the pores and opens the barrier. Besides, the filtrating capability of such masks is usually limited to particles above 300 nm diameter, whereas the coronavirus may range around 50 to 200 nm diameter only. However, new materials and fabrication technologies might be promising alternatives, such as a recently developed electrospun textile based on silk and graphene. Due to the ultra-high aspect ratio of graphene, a mat with a pore size below 10 nm is created, blocking nano-pollutants including viruses while maintaining the passage of air.

 

Materials song list for New Year’s

Earlier this year I put together a song list for summer picnics, identifying songs with a materials edge. For New Year’s, I searched for the same but came up short.

The materials motif I notice for New Year’s songs includes a lot of sustainability & renewable energy with a fair amount of materials chemistry; some metals & alloys, polymers, photonics, silicon dioxide, and mechanical properties; then smithereens of Au, phase transformation, metamaterials, ceramics, crystalline structure, fatigue, graphene, solar energy, membranes, transparency, magnetoresistive random-access memory, and space materials.

Well, okay, that sounds like a lot.

But the problem is that all of these are a real stretch. I match silicon dioxide to one line: passin' round the bottle; ceramics to cup of kindness; metals & alloys to ring in the New Year; and polymers to glitter.

The rest is even a greater stretch: magnetoresistive random-access memory to a mention of memories. Any words related to an ending (of the old year) and a beginning (of the new year) – sustainability. 

From a writing-point-of-view, songs about New Year’s (that I found) carry very few metaphors. This makes me want to come up with some New Year’s lyrics myself – maybe a project for next year!

It’s a great set of songs, though; so here’s the list. Happy New Year’s!

Taylor Swift New Year’s Day (polymers, magnetoresistive random-access memory)

Mariah Carey Auld Lang Syne (materials chemistry, ceramics)

Prince 1999 (lyrics) (materials chemistry, sustainability)

Eagles Funky New Year (lyrics) (silicon dioxide, phase transformation)

U2 New Year’s Day (Au, renewable energy)

Bon Jovi New Year’s Day (metals & alloys, organic materials)

Regina Spektor My dear acquaintance (Happy New Year) (lyrics) (SiO₂, mechanical properties)

Europe The final countdown (space materials)

Sugarland Maybe Baby (New Year’s Day) (lyrics) (photonics)

Goo Goo Dolls Better days (sustainability)

Death Cab for Cutie The new year (crystalline structure, fatigue, graphene)

Pentatonix New Year’s Day (polymers, materials chemistry)

Otis Redding and Carla Thomas New Year’s resolution (lyrics) (metamaterials)

Ella Fitzgerald What are you doing New Year’s eve? (lyrics) (metals & alloys)

B.B. King Bringing in a brand new year (lyrics) (space materials, sustainability)

Van Morrison Celtic New Year (transparency, materials chemistry)

A Great Big World This is the New Year (NOW what’s next!) (solar energy, membranes, mechanical properties)

-compiled by Judy Meiksin

The G-filter: The simple high tech solution to India's water pollution

As Abdul Rajak Khan kneads the clay for his Gravity Filter, the sights and sounds of the village are all around him.

Loose brown soil drifts from the ground floating over unplastered red brick buildings. 

Copper bangles clatter as women pound hard mud with a bat, breaking it down to powder the consistency of dust. 

It is even in the way Abdul says ‘Mitti achchi hai’. The soil is good. It has salts which give it strength, and whiteness that has come to define pottery from Jodhpur. 

Like most cities in the Indian state of Rajasthan, Jodhpur is a dense panoply of palaces and forts set in the stark landscape of the Thar Desert. The dry season lasts the whole year with meager rains supplying most of the water for nearly a million people, in addition to livestock. 

Much of this water also happens to be polluted with heavy metals, fecal matter, and bacteria such as E. coli that cause diarrhea. 

The G-filter that Abdul is preparing is a homemade solution that promises clean affordable drinking water to the Indian rural community.  

From the outside, it looks like any other garden variety flower pot, a wheatish brown frustum that fits inside another bucket. On a good day, the G-filter can produce up to a liter of pure water every hour that is then collected through a tap attached to the outer vessel. 

While ceramic filters are quite common all over the world, the G-filter is made by local Indian potters through indigenous technology using only locally sourced raw materials. In Jodhpur, the scientific effort to study and standardize the filter is led by Prof Anand Plappally and his graduate students Sandeep Gupta, Amrita Kaurwar, and Raj Kumar Satankar from the nearby Indian Institute of Technology (IIT) Jodhpur. 

“In India, there is a potter in every village. Our goal is to help them create effective water filters using techniques that they are familiar with,” Prof Plappally tells me over the phone. “We don’t need to teach them much about the traditional manufacturing process - they have been doing it for years.” Instead, the research team helps them in selecting suitable raw materials, fine-tuning specific processing parameters, and in final product testing. The wares are shaped using a locally manufactured molding press. “The potter sells his products in the nearby market, thus avoiding transport costs. Not only does the overall health improve but also the economy,” Prof Plappally says.

His graduate student, Amrita Kaurwar, who led much of the material studies, says, “What differentiates the G-filter from other ceramic filters is that it is made in open earth kilns within potter households from raw materials that are locally available at Jodhpur. This includes sawdust from the local carpenter's shop, salty clays, oxidizing matter from bajri (saltpeter), and marble dust.” 

Marble is one of Rajasthan’s major exports. The white marble used to construct the iconic Taj Mahal was quarried from Makrana, a mere 150 miles from Jodhpur. 

“The salts decrease the temperature at which the filter needs to be baked, reducing the fuel bill. The burnt calcium carbonates help in killing harmful bacteria such as E Coli and is effective to a lesser extent in removing heavy metals such as arsenic. The filtered water has no traceable amount of pathogens and is the best option that most villages currently have,” Amrita says.

Amrita now lives in Pune, a large city in the southern state of Maharashtra where she moved with her husband and son after she obtained her PhD degree in March 2019. 

Oddly, the "village" is here too: It is in the indistinct clamor of the street vendors whose voices unceremoniously cut into our phone conversation. 

India and its villages are deeply intertwined, like a crab and its shell. They share similar destinies and sorrows, what is home and shelter is also what limits mobility and growth. 

Most of the water in the country is severely polluted with microbial growth many times above what would be considered scandalous in the Western world. The Ganges River in the north carries upwards of 9 billion liters of industrial waste and sewage every day. Most of the rivers are clogged with plastic, chemicals, and feces. Potable drinking water is fast becoming not just an urgent civic concern but also a major political issue. The southern city of Chennai, one of the major metropolitan cities of the nation, is facing the worst water shortage in its history and 7 million residents are pointing fingers at local politicians. 

The lessers rivers, cities, and villages are no exception. Bacteria such as E. coli that cause diarrhea and even death are widespread. 

Now that she is the mother of a four-month-old, the quality of drinking water is very much on Amrita’s mind as she explains how the G-filter works. “The pores of the filter are between 10 nanometers and 1 micrometer. These pores are too small for the bacteria to get through.” 

Interestingly, without the marble dust, the E Coli filtration rate is 99.99%. With marble, this increases to 99.999%. At this rate, it is virtually untraceable. 

Much of Amrita’s work has been to detail the scientific nature of the filters and to quantify the filtration parameters. She has established among other things that the filter works best at an ambient temperature of 35°C, even though the drop off on either side is minimal. She has studied the role of other additives such as iron in the ceramic body. The results suggest that iron improves the removal of arsenic. 

A major part of their work has been to measure how effective the filter is in removing microbes. This was done through the setup shown in the figure. Ambient water is spiked with a known strain of E. coli and is allowed to pass through the filter. The number of cells pre- and post-filtration is carefully calculated which yields the rates mentioned before. 

Schematic of microbial filtration set up. From Gupta et al, International Journal for Service Learning in Engineering, Humanitarian Engineering and Social Entrepreneurship, Vol. 13, No. 1, pp. 53-66, Spring 2018

Thanks to their efforts, the G-filter is taking a life of its own and is becoming popular not just in Rajasthan but also in faraway states such as Bihar, Kerala, and Tamil Nadu. This is in no small part due to the work of NGOs such as Rupayan Sansthan, Enactus-IIT Madras and the S M Sehgal foundation that has come forward to promote the product.

The potter can sell fully functional filters with clay storage containers priced at around 600 Indian rupees or roughly ten US dollars. 

A typical filter can last anywhere from six months to a year with an occasional cleaning. The NGOs take no part of the profit. They teach the technique to local potters and help standardize their wares. The potters sell them wherever they like. 

The research group working on the G-filter has more than 10 publications in journals and books, with more in progress. 

But the real reward, both of them assure me, is in the villages across India where their work will translate to good health, happiness, and prosperity. 

______

Watch Rajak Khan make the G-filter in the following video. 

 

 

 

Where were you when Apollo 11 landed on the moon?

Three space experts react very differently to the July 20, 1969 Apollo 11 landing in this video:

The producers of this video, released 10 days ago by Nature, do a fantastic job, I think, of capturing very different takes in science communication. They could have simply held up a microphone and ask, “Where were you when Apollo 11 landed?” and, of course, some of the interviewees they could have chosen may not even have been born yet. So they might have modified their question and ask, “What do you think about the 50^th anniversary of this landing?”

The producers, however, do much better. They film two researchers and one aviator as they watch film footage of the actual landing. The camera focuses on the women, but includes a box in the top corner that shows us viewers what they’re seeing.

Watching the NASA film footage elicits reactions from the women that would not have been possible with simply a mic and a question.

As the film footage shows the landing

Sara Russell (researches planetary materials): I can see the dust starting to come up now, so it’s actually very hard to see anything on the surface….

Marissa Lo (studies lunar volcanology): You can see that they’re just sort of landing onto an area with absolutely no craters….

Wally Funk (aviator): He’s being told what to do when you’re coming down for a landing. It’s just like when I’m coming in for an aeroplane landing.

Isn’t this cool as each interviewee notices something related to her specific interest?

As the film footage shows the astronauts on the moon

Marissa Lo (lunar volcanology): He’s describing what the surface is like here, so this would have been the first time that someone has seen what the lunar regolith is like. So the lunar regolith is like the soil that’s on top of the surface of the moon….They’re collecting a core tube sample. We do this for a lot of rocks and, actually, glaciers on Earth as, say, ice or rocks are deposited over time, that’s recording a history as you’re going deeper into the ground.

Comments after watching the NASA film footage

Sara Russell (planetary materials): And we’re still studying these rocks now, 50 years later ….Before Apollo, we had no idea how the moon got there….This giant impact of a Mars-size body into the Earth that smashed into it and then splashed material out that coalesced to form the Moon.

Wally Funk (aviator): You can’t jump from there to Apollo. You have to learn to fly, you have to learn to fly jets, and you have to understand how the gravity works.

Sara Russell, leader of the Planetary Materials Group at the Natural History Museum, London, was only 2 years old during the landing. Marissa Lo, PhD student researching lunar volcanology at the University of Manchester, was not born yet. And Wally Funk, aviator, was part of the Mercury 13, a privately funded Women in Space Program.

By choosing representatives from 3 generations, the producers provide a range of reactions.

Furthermore, by asking them to watch the film footage, the producers elicit very detailed responses that correlate with their fields, enabling them to continue giving detailed impressions afterwards.

Now, for your reading pleasure, science writer Omar Fabián published this article about a materials researcher receiving a briefing in Houston, 1969, about the moon rocks they’ll be studying. The researcher was sort of not interested until he heard the word lexan….

-Judy Meiksin