Tag Archives: University of Colorado Boulder

Space junk clogs up low-Earth orbit

Arianne Cohen’s May 28, 2020 article for Fast Company concisely sums up the space junk problem and solution (Note: A link has been removed),

Throwing money at problems works in space, too! A paper in the Proceedings of the National Academy of Sciences [PNAS] says that the space debris problem can be fixed once and for all, not by the engineers and scientists who consider space their domain, but with cold, hard cash: about $235,000 per satellite. Such a plan would create financial barriers for smaller organizations.

This looks pretty doesn’t it? hard to believe it’s a representation of the junk yard that floats around the earth.

Caption: A computer-generated image representing space debris as could be seen from high Earth orbit. The two main debris fields are the ring of objects in geosynchronous Earth orbit and the cloud of objects in low Earth orbit. Credit: NASA

For those who like a little more detail, a May 25, 2020 University of Colorado at Boulder news release (also on EurekAlert) presents the idea for orbital user fees as a means of limiting the amount of space junk,

Space is getting crowded. Aging satellites and space debris crowd low-Earth orbit, and launching new satellites adds to the collision risk. The most effective way to solve the space junk problem, according to a new study, is not to capture debris or deorbit old satellites: it’s an international agreement to charge operators “orbital-use fees” for every satellite put into orbit.

Orbital use fees would also increase the long-run value of the space industry, said economist Matthew Burgess, a CIRES [Cooperative Institute for Research in Environmental Sciences] Fellow and co-author of the new paper. By reducing future satellite and debris collision risk, an annual fee rising to about $235,000 per satellite would quadruple the value of the satellite industry by 2040, he and his colleagues concluded in a paper published today in the Proceedings of the National Academy of Sciences.

“Space is a common resource, but companies aren’t accounting for the cost their satellites impose on other operators when they decide whether or not to launch,” said Burgess, who is also an assistant professor in Environmental Studies and an affiliated faculty member in Economics at the University of Colorado Boulder. “We need a policy that lets satellite operators directly factor in the costs their launches impose on other operators.”

Currently, an estimated 20,000 objects–including satellites and space debris–are crowding low-Earth orbit. It’s the latest Tragedy of the Commons, the researchers said: Each operator launches more and more satellites until their private collision risk equals the value of the orbiting satellite.

So far, proposed solutions have been primarily technological or managerial, said Akhil Rao, assistant professor of economics at Middlebury College and the paper’s lead author. Technological fixes include removing space debris from orbit with nets, harpoons, or lasers. Deorbiting a satellite at the end of its life is a managerial fix.

Ultimately, engineering or managerial solutions like these won’t solve the debris problem because they don’t change the incentives for operators. For example, removing space debris might motivate operators to launch more satellites–further crowding low-Earth orbit, increasing collision risk, and raising costs. “This is an incentive problem more than an engineering problem. What’s key is getting the incentives right,” Rao said.

A better approach to the space debris problem, Rao and his colleagues found, is to implement an orbital-use fee–a tax on orbiting satellites. “That’s not the same as a launch fee,” Rao said, “Launch fees by themselves can’t induce operators to deorbit their satellites when necessary, and it’s not the launch but the orbiting satellite that causes the damage.”

Orbital-use fees could be straight-up fees or tradeable permits, and they could also be orbit-specific, since satellites in different orbits produce varying collision risks. Most important, the fee for each satellite would be calculated to reflect the cost to the industry of putting another satellite into orbit, including projected current and future costs of additional collision risk and space debris production–costs operators don’t currently factor into their launches. “In our model, what matters is that satellite operators are paying the cost of the collision risk imposed on other operators,” said Daniel Kaffine, professor of economics and RASEI Fellow at the University of Colorado Boulder and co-author on the paper.

And those fees would increase over time, to account for the rising value of cleaner orbits. In the researchers’ model, the optimal fee would rise at a rate of 14 percent per year, reaching roughly $235,000 per satellite-year by 2040.

For an orbital-use fee approach to work, the researchers found, all countries launching satellites would need to participate–that’s about a dozen that launch satellites on their own launch vehicles and more than 30 that own satellites. In addition, each country would need to charge the same fee per unit of collision risk for each satellite that goes into orbit, although each country could collect revenue separately. Countries use similar approaches already in carbon taxes and fisheries management.

In this study, Rao and his colleagues compared orbital-use fees to business as usual (that is, open access to space) and to technological fixes such as removing space debris. They found that orbital use fees forced operators to directly weigh the expected lifetime value of their satellites against the cost to industry of putting another satellite into orbit and creating additional risk. In other scenarios, operators still had incentive to race into space, hoping to extract some value before it got too crowded.

With orbital-use fees, the long-run value of the satellite industry would increase from around $600 billion under the business-as-usual scenario to around $3 trillion, researchers found. The increase in value comes from reducing collisions and collision-related costs, such as launching replacement satellites.

Orbital-use fees could also help satellite operators get ahead of the space junk problem. “In other sectors, addressing the Tragedy of the Commons has often been a game of catch-up with substantial social costs. But the relatively young space industry can avoid these costs before they escalate,” Burgess said.

Here’s a link to and a citation for the paper,

Orbital-use fees could more than quadruple the value of the space industry by Akhil Rao, Matthew G. Burgess, and Daniel Kaffine. DOI: https://doi.org/10.1073/pnas.1921260117 PNAS first published May 26, 2020

This paper is behind a paywall.

Some amusements in the time of COVID-19

Gold stars for everyone who recognized the loose paraphrasing of the title, Love in the Time of Cholera, for Gabrial Garcia Marquez’s 1985 novel.

I wrote my headline and first paragraph yesterday and found this in my email box this morning, from a March 25, 2020 University of British Columbia news release, which compares times, diseases, and scares of the past with today’s COVID-19 (Perhaps politicians and others could read this piece and stop using the word ‘unprecedented’ when discussing COVID-19?),

How globalization stoked fear of disease during the Romantic era

In the late 18th and early 19th centuries, the word “communication” had several meanings. People used it to talk about both media and the spread of disease, as we do today, but also to describe transport—via carriages, canals and shipping.

Miranda Burgess, an associate professor in UBC’s English department, is working on a book called Romantic Transport that covers these forms of communication in the Romantic era and invites some interesting comparisons to what the world is going through today.

We spoke with her about the project.

What is your book about?

It’s about global infrastructure at the dawn of globalization—in particular the extension of ocean navigation through man-made inland waterways like canals and ship’s canals. These canals of the late 18th and early 19th century were like today’s airline routes, in that they brought together places that were formerly understood as far apart, and shrunk time because they made it faster to get from one place to another.

This book is about that history, about the fears that ordinary people felt in response to these modernizations, and about the way early 19th-century poets and novelists expressed and responded to those fears.

What connections did those writers make between transportation and disease?

In the 1810s, they don’t have germ theory yet, so there’s all kinds of speculation about how disease happens. Works of tropical medicine, which is rising as a discipline, liken the human body to the surface of the earth. They talk about nerves as canals that convey information from the surface to the depths, and the idea that somehow disease spreads along those pathways.

When the canals were being built, some writers opposed them on the grounds that they could bring “strangers” through the heart of the city, and that standing water would become a breeding ground for disease. Now we worry about people bringing disease on airplanes. It’s very similar to that.

What was the COVID-19 of that time?

Probably epidemic cholera [emphasis mine], from about the 1820s onward. The Quarterly Review, a journal that novelist Walter Scott was involved in editing, ran long articles that sought to trace the map of cholera along rivers from South Asia, to Southeast Asia, across Europe and finally to Britain. And in the way that its spread is described, many of the same fears that people are evincing now about COVID-19 were visible then, like the fear of clothes. Is it in your clothes? Do we have to burn our clothes? People were concerned.

What other comparisons can be drawn between those times and what is going on now?

Now we worry about the internet and “fake news.” In the 19th century, they worried about what William Wordsworth called “the rapid communication of intelligence,” which was the daily newspaper. Not everybody had access to newspapers, but each newspaper was read by multiple families and newspapers were available in taverns and coffee shops. So if you were male and literate, you had access to a newspaper, and quite a lot of women did, too.

Paper was made out of rags—discarded underwear. Because of the French Revolution and Napoleonic Wars that followed, France blockaded Britain’s coast and there was a desperate shortage of rags to make paper, which had formerly come from Europe. And so Britain started to import rags from the Caribbean that had been worn by enslaved people.

Papers of the time are full of descriptions of the high cost of rags, how they’re getting their rags from prisons, from prisoners’ underwear, and fear about the kinds of sweat and germs that would have been harboured in those rags—and also discussions of scarcity, as people stole and hoarded those rags. It rings very well with what the internet is telling us now about a bunch of things around COVID-19.

Plus ça change, n’est-ce pas?

And now for something completely different

Kudos to all who recognized the Monty Python reference. Now, onto the frogfish,

Thank you to the Monterey Bay Aquarium (in California, US).

A March 22, 2020 University of Washington (state) news release features an interview with the author of a new book on frogfishes,

Any old fish can swim. But what fish can walk, scoot, clamber over rocks, change color or pattern and even fight? That would be the frogfish.

The latest book by Ted Pietsch, UW professor emeritus of aquatic and fishery sciences, explores the lives and habits of these unusual marine shorefishes. “Frogfishes: Biodiversity, Zoogeography, and Behavioral Ecology” was published in March [2020] by Johns Hopkins University Press.

Pietsch, who is also curator emeritus of fishes at the Burke Museum of Natural History and Culture, has published over 200 articles and a dozen books on the biology and behavior of marine fishes. He wrote this book with Rachel J. Arnold, a faculty member at Northwest Indian College in Bellingham and its Salish Sea Research Center.

These walking fishes have stepped into the spotlight lately, with interest growing in recent decades. And though these predatory fishes “will almost certainly devour anything else that moves in a home aquarium,” Pietsch writes, “a cadre of frogfish aficionados around the world has grown within the dive community and among aquarists.” In fact, Pietsch said, there are three frogfish public groups on Facebook, with more than 6,000 members.

First, what is a frogfish?

Ted Pietsch: A member of a family of bony fishes, containing 52 species, all of which are highly camouflaged and whose feeding strategy consists of mimicking the immobile, inert, and benign appearance of a sponge or an algae-encrusted rock, while wiggling a highly conspicuous lure to attract prey.

This is a fish that “walks” and “hops” across the sea bottom, and clambers about over rocks and coral like a four-legged terrestrial animal but, at the same time, can jet-propel itself through open water. Some lay their eggs encapsulated in a complex, floating, mucus mass, called an “egg raft,” while some employ elaborate forms of parental care, carrying their eggs around until they hatch.

They are among the most colorful of nature’s productions, existing in nearly every imaginable color and color pattern, with an ability to completely alter their color and pattern in a matter of days or seconds. All these attributes combined make them one of the most intriguing groups of aquatic vertebrates for the aquarist, diver, and underwater photographer as well as the professional zoologist.

I couldn’t resist the ‘frog’ reference and I’m glad since this is a good read with a number of fascinating photographs and illustrations.,

An illustration of the frogfish Antennarius pictus, published by George Shaw in 1794. From a new book by Ted Pietsch, UW professor of emeritus of aquatic and fishery sciences. Courtesy: University of Washington (state)

h/t phys.org March 24, 2020 news item

Building with bacteria

A block of sand particles held together by living cells. Credit: The University of Colorado Boulder College of Engineering and Applied Science

A March 24, 2020 news item on phys.org features the future of building construction as perceived by synthetic biologists,

Buildings are not unlike a human body. They have bones and skin; they breathe. Electrified, they consume energy, regulate temperature and generate waste. Buildings are organisms—albeit inanimate ones.

But what if buildings—walls, roofs, floors, windows—were actually alive—grown, maintained and healed by living materials? Imagine architects using genetic tools that encode the architecture of a building right into the DNA of organisms, which then grow buildings that self-repair, interact with their inhabitants and adapt to the environment.

A March 23, 2020 essay by Wil Srubar (Professor of Architectural Engineering and Materials Science, University of Colorado Boulder), which originated the news item, provides more insight,

Living architecture is moving from the realm of science fiction into the laboratory as interdisciplinary teams of researchers turn living cells into microscopic factories. At the University of Colorado Boulder, I lead the Living Materials Laboratory. Together with collaborators in biochemistry, microbiology, materials science and structural engineering, we use synthetic biology toolkits to engineer bacteria to create useful minerals and polymers and form them into living building blocks that could, one day, bring buildings to life.

In one study published in Scientific Reports, my colleagues and I genetically programmed E. coli to create limestone particles with different shapes, sizes, stiffnesses and toughness. In another study, we showed that E. coli can be genetically programmed to produce styrene – the chemical used to make polystyrene foam, commonly known as Styrofoam.

Green cells for green building

In our most recent work, published in Matter, we used photosynthetic cyanobacteria to help us grow a structural building material – and we kept it alive. Similar to algae, cyanobacteria are green microorganisms found throughout the environment but best known for growing on the walls in your fish tank. Instead of emitting CO2, cyanobacteria use CO2 and sunlight to grow and, in the right conditions, create a biocement, which we used to help us bind sand particles together to make a living brick.

By keeping the cyanobacteria alive, we were able to manufacture building materials exponentially. We took one living brick, split it in half and grew two full bricks from the halves. The two full bricks grew into four, and four grew into eight. Instead of creating one brick at a time, we harnessed the exponential growth of bacteria to grow many bricks at once – demonstrating a brand new method of manufacturing materials.

Researchers have only scratched the surface of the potential of engineered living materials. Other organisms could impart other living functions to material building blocks. For example, different bacteria could produce materials that heal themselves, sense and respond to external stimuli like pressure and temperature, or even light up. If nature can do it, living materials can be engineered to do it, too.

It also take less energy to produce living buildings than standard ones. Making and transporting today’s building materials uses a lot of energy and emits a lot of CO2. For example, limestone is burned to make cement for concrete. Metals and sand are mined and melted to make steel and glass. The manufacture, transport and assembly of building materials account for 11% of global CO2 emissions. Cement production alone accounts for 8%. In contrast, some living materials, like our cyanobacteria bricks, could actually sequester CO2.

The field of engineered living materials is in its infancy, and further research and development is needed to bridge the gap between laboratory research and commercial availability. Challenges include cost, testing, certification and scaling up production. Consumer acceptance is another issue. For example, the construction industry has a negative perception of living organisms. Think mold, mildew, spiders, ants and termites. We’re hoping to shift that perception. Researchers working on living materials also need to address concerns about safety and biocontamination.

The [US] National Science Foundation recently named engineered living materials one of the country’s key research priorities. Synthetic biology and engineered living materials will play a critical role in tackling the challenges humans will face in the 2020s and beyond: climate change, disaster resilience, aging and overburdened infrastructure, and space exploration.

If you have time and interest, this is fascinating. Strubar is a little exuberant and, at this point, I welcome it.

Fitness

The Lithuanians are here for us. Scientists from the Kaunas University of Technology have just published a paper on better exercises for lower back pain in our increasingly sedentary times, from a March 23, 2020 Kaunas University of Technology press release (also on EurekAlert) Note: There are a few minor grammatical issues,

With the significant part of the global population forced to work from home, the occurrence of lower back pain may increase. Lithuanian scientists have devised a spinal stabilisation exercise programme for managing lower back pain for people who perform a sedentary job. After testing the programme with 70 volunteers, the researchers have found that the exercises are not only efficient in diminishing the non-specific lower back pain, but their effect lasts 3 times longer than that of a usual muscle strengthening exercise programme.

According to the World Health Organisation, lower back pain is among the top 10 diseases and injuries that are decreasing the quality of life across the global population. It is estimated that non-specific low back pain is experienced by 60% to 70% of people in industrialised societies. Moreover, it is the leading cause of activity limitation and work absence throughout much of the world. For example, in the United Kingdom, low back pain causes more than 100 million workdays lost per year, in the United States – an estimated 149 million.

Chronic lower back pain, which starts from long-term irritation or nerve injury affects the emotions of the afflicted. Anxiety, bad mood and even depression, also the malfunctioning of the other bodily systems – nausea, tachycardia, elevated arterial blood pressure – are among the conditions, which may be caused by lower back pain.

During the coronavirus disease (COVID-19) outbreak, with a significant part of the global population working from home and not always having a properly designed office space, the occurrence of lower back pain may increase.

“Lower back pain is reaching epidemic proportions. Although it is usually clear what is causing the pain and its chronic nature, people tend to ignore these circumstances and are not willing to change their lifestyle. Lower back pain usually comes away itself, however, the chances of the recurring pain are very high”, says Dr Irina Klizienė, a researcher at Kaunas University of Technology (KTU) Faculty of Social Sciences, Humanities and Arts.

Dr Klizienė, together with colleagues from KTU and from Lithuanian Sports University has designed a set of stabilisation exercises aimed at strengthening the muscles which support the spine at the lower back, i.e. lumbar area. The exercise programme is based on Pilates methodology.

According to Dr Klizienė, the stability of lumbar segments is an essential element of body biomechanics. Previous research evidence shows that in order to avoid the lower back pain it is crucial to strengthen the deep muscles, which are stabilising the lumbar area of the spine. One of these muscles is multifidus muscle.

“Human central nervous system is using several strategies, such as preparing for keeping the posture, preliminary adjustment to the posture, correcting the mistakes of the posture, which need to be rectified by specific stabilising exercises. Our aim was to design a set of exercises for this purpose”, explains Dr Klizienė.

The programme, designed by Dr Klizienė and her colleagues is comprised of static and dynamic exercises, which train the muscle strength and endurance. The static positions are to be held from 6 to 20 seconds; each exercise to be repeated 8 to 16 times.

Caption: The static positions are to be held from 6 to 20 seconds; each exercise to be repeated 8 to 16 times. Credit: KTU

The previous set is a little puzzling but perhaps you’ll find these ones below easier to follow,

Caption: The exercises are aimed at strengthening the muscles which support the spine at the lower back. Credit: KTU

I think more pictures of intervening moves would have been useful. Now. getting back to the press release,

In order to check the efficiency of the programme, 70 female volunteers were randomly enrolled either to the lumbar stabilisation exercise programme or to a usual muscle strengthening exercise programme. Both groups were exercising twice a week for 45 minutes for 20 weeks. During the experiment, ultrasound scanning of the muscles was carried out.

As soon as 4 weeks in lumbar stabilisation programme, it was observed that the cross-section area of the multifidus muscle of the subjects of the stabilisation group has increased; after completing the programme, this increase was statistically significant (p < 0,05). This change was not observed in the strengthening group.

Moreover, although both sets of exercises were efficient in eliminating lower back pain and strengthening the muscles of the lower back area, the effect of stabilisation exercises lasted 3 times longer – 12 weeks after the completion of the stabilisation programme against 4 weeks after the completion of the muscle strengthening programme.

“There are only a handful of studies, which have directly compared the efficiency of stabilisation exercises against other exercises in eliminating lower back pain”, says Dr Klizienė, “however, there are studies proving that after a year, lower back pain returned only to 30% of people who have completed a stabilisation exercise programme, and to 84% of people who haven’t taken these exercises. After three years these proportions are 35% and 75%.”

According to her, research shows that the spine stabilisation exercises are more efficient than medical intervention or usual physical activities in curing the lower back pain and avoiding the recurrence of the symptoms in the future.

Here’s a link to and a citation for the paper,

Effect of different exercise programs on non-specific chronic low back pain and disability in people who perform sedentary work by Saule Sipavicienea, Irina Klizieneb. Clinical Biomechanics March 2020 Volume 73, Pages 17–27 DOI: https://doi.org/10.1016/j.clinbiomech.2019.12.028

This paper is behind a paywall.

Desalination with nanowood

A new treatment for wood could make renewable salt-separating membranes. Courtesy: University of Maryland

An August 6, 2019 article by Adele Peters for Fast Company describes a ‘wooden’approach to water desalinization (also known as desalination),

“We are trying to develop a new type of membrane material that is nature-based,” says Z. Jason Ren, an engineering professor at Princeton University and one of the coauthors of a new paper in Science Advances about that material, which is made from wood. It’s designed for use in a process called membrane distillation, which heats up saltwater and uses pressure to force the water vapor through a membrane, leaving the salt behind and creating pure water. The membranes are usually made from a type of plastic. Using “nanowood” membranes instead can both improve the energy efficiency of the process and avoid the environmental problems of plastic.

An August 2, 2019 University of Maryland (UMD) news release provides more detail about the research,

A membrane made of a sliver of wood could be the answer to renewably sourced water cleaning. Most membranes that are currently used to distill fresh water from salty are made of polymers based on fossil fuels.

Inspired by the intricate system of water circulating in a tree, a research team from the University of Maryland, Princeton University, and the University of Colorado Boulder have figured out how to use a thin slice of wood as a membrane through which water vapor can evaporate, leaving behind salt or other contaminants.

“This work demonstrates another exciting energy/water application of nanostructured wood, as a high-performance membrane material,” said Liangbing Hu, a professor of materials science and engineering at UMD’s A. James Clark School of Engineering, who co-led the study.

The team chemically treated the wood to become hydrophobic, so that it more efficiently allows water vapor through, driven by a heat source like solar energy.

“This study discovered a new way of using wood materials’ unique properties as both an excellent insulator and water vapor transporter,” said Z. Jason Ren, a professor in environmental engineering who recently moved from CU Boulder to Princeton, and the other co-leader of the team that performed the study.

The researchers treat the wood so that it loses its lignin, the part of the wood that makes it brown and rigid, and its hemicellulose, which weaves in and out between cellulose to hold it in place. The resulting “nanowood” is treated with silane, a compound used to make silicon for computer chips. The semiconducting nature of the compound maintains the wood’s natural nanostructures of cellulose, and clings less to water vapor molecules as they pass through. Silane is also used in solar cell manufacturing.

The membrane looks like a thin piece of wood, seemingly bleached white, that is suspended above a source of water vapor. As the water heats and passes into the gas phase, the molecules are small enough to fit through the tiny channels lining the walls of the leftover cell structure. Water collected on the other side is now free of large contaminants like salt.
To test it, the researchers distilled water through it and found that it performed 1.2 times better than a conventional membrane.

“The wood membrane has very high porosity, which promotes water vapor transport and prevents heat loss,” said first author Dianxun Hou, who was a student at CU Boulder.
Inventwood, a UMD spinoff company of Hu’s research group, is working on commercializing wood based nanotechnologies.

Here’s a link to and a citation for the paper,

Hydrophobic nanostructured wood membrane for thermally efficient distillation by Dianxun Hou, Tian Li, Xi Chen, Shuaiming He, Jiaqi Dai, Sohrab A. Mofid, Deyin Hou, Arpita Iddya, David Jassby, Ronggui Yang, Liangbing Hu, and Zhiyong Jason Ren. Science Advances 02 Aug 2019: Vol. 5, no. 8, eaaw3203 DOI: 10.1126/sciadv.aaw3203

This paper appears to be open access.

In my brief survey of the paper, I noticed that the researchers were working with cellulose nanofibrils (CNF), a term which should be familiar for anyone following the nanocellulose story, such as it.

Low-cost carbon sequestration and eco-friendly manufacturing for chemicals with nanobio hybrid organisms

Years ago I was asked about carbon sequestration and nanotechnology and could not come up with any examples. At last I have something for the next time the question is asked. From a June 11, 2019 news item on ScienceDaily,

University of Colorado Boulder researchers have developed nanobio-hybrid organisms capable of using airborne carbon dioxide and nitrogen to produce a variety of plastics and fuels, a promising first step toward low-cost carbon sequestration and eco-friendly manufacturing for chemicals.

By using light-activated quantum dots to fire particular enzymes within microbial cells, the researchers were able to create “living factories” that eat harmful CO2 and convert it into useful products such as biodegradable plastic, gasoline, ammonia and biodiesel.

A June 11, 2019 University of Colorado at Boulder news release (also on EurekAlert) by Trent Knoss, which originated the news item, provides a deeper dive into the research,

“The innovation is a testament to the power of biochemical processes,” said Prashant Nagpal, lead author of the research and an assistant professor in CU Boulder’s Department of Chemical and Biological Engineering. “We’re looking at a technique that could improve CO2 capture to combat climate change and one day even potentially replace carbon-intensive manufacturing for plastics and fuels.”

The project began in 2013, when Nagpal and his colleagues began exploring the broad potential of nanoscopic quantum dots, which are tiny semiconductors similar to those used in television sets. Quantum dots can be injected into cells passively and are designed to attach and self-assemble to desired enzymes and then activate these enzymes on command using specific wavelengths of light.

Nagpal wanted to see if quantum dots could act as a spark plug to fire particular enzymes within microbial cells that have the means to convert airborne CO2 and nitrogen, but do not do so naturally due to a lack of photosynthesis.

By diffusing the specially-tailored dots into the cells of common microbial species found in soil, Nagpal and his colleagues bridged the gap. Now, exposure to even small amounts of indirect sunlight would activate the microbes’ CO2 appetite, without a need for any source of energy or food to carry out the energy-intensive biochemical conversions.

“Each cell is making millions of these chemicals and we showed they could exceed their natural yield by close to 200 percent,” Nagpal said.

The microbes, which lie dormant in water, release their resulting product to the surface, where it can be skimmed off and harvested for manufacturing. Different combinations of dots and light produce different products: Green wavelengths cause the bacteria to consume nitrogen and produce ammonia while redder wavelengths make the microbes feast on CO2 to produce plastic instead.

The process also shows promising signs of being able to operate at scale. The study found that even when the microbial factories were activated consistently for hours at a time, they showed few signs of exhaustion or depletion, indicating that the cells can regenerate and thus limit the need for rotation.

“We were very surprised that it worked as elegantly as it did,” Nagpal said. “We’re just getting started with the synthetic applications.”

The ideal futuristic scenario, Nagpal said, would be to have single-family homes and businesses pipe their CO2 emissions directly to a nearby holding pond, where microbes would convert them to a bioplastic. The owners would be able to sell the resulting product for a small profit while essentially offsetting their own carbon footprint.

“Even if the margins are low and it can’t compete with petrochemicals on a pure cost basis, there is still societal benefit to doing this,” Nagpal said. “If we could convert even a small fraction of local ditch ponds, it would have a sizeable impact on the carbon output of towns. It wouldn’t be asking much for people to implement. Many already make beer at home, for example, and this is no more complicated.”

The focus now, he said, will shift to optimizing the conversion process and bringing on new undergraduate students. Nagpal is looking to convert the project into an undergraduate lab experiment in the fall semester, funded by a CU Boulder Engineering Excellence Fund grant. Nagpal credits his current students with sticking with the project over the course of many years.

“It has been a long journey and their work has been invaluable,” he said. “I think these results show that it was worth it.”

Here’s a link to and a citation for the paper,

Nanorg Microbial Factories: Light-Driven Renewable Biochemical Synthesis Using Quantum Dot-Bacteria Nanobiohybrids by Yuchen Ding, John R. Bertram, Carrie Eckert, Rajesh Reddy Bommareddy, Rajan Patel, Alex Conradie, Samantha Bryan, Prashant Nagpal. J. Am. Chem. Soc.2019XXXXXXXXXX-XXX DOI: https://doi.org/10.1021/jacs.9b02549 Publication Date:June 7, 2019
Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Solar cells and ‘tinkertoys’

A Nov. 3, 2014 news item on Nanowerk features a project researchers hope will improve photovoltaic efficiency and make solar cells competitive with other sources of energy,

 Researchers at Sandia National Laboratories have received a $1.2 million award from the U.S. Department of Energy’s SunShot Initiative to develop a technique that they believe will significantly improve the efficiencies of photovoltaic materials and help make solar electricity cost-competitive with other sources of energy.

The work builds on Sandia’s recent successes with metal-organic framework (MOF) materials by combining them with dye-sensitized solar cells (DSSC).

“A lot of people are working with DSSCs, but we think our expertise with MOFs gives us a tool that others don’t have,” said Sandia’s Erik Spoerke, a materials scientist with a long history of solar cell exploration at the labs.

A Nov. 3, 2014 Sandia National Laboratories news release, which originated the news item, describes the project and the technology in more detail,

Sandia’s project is funded through SunShot’s Next Generation Photovoltaic Technologies III program, which sponsors projects that apply promising basic materials science that has been proven at the materials properties level to demonstrate photovoltaic conversion improvements to address or exceed SunShot goals.

The SunShot Initiative is a collaborative national effort that aggressively drives innovation with the aim of making solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, the Energy Department supports efforts by private companies, universities and national laboratories to drive down the cost of solar electricity to 6 cents per kilowatt-hour.

DSSCs provide basis for future advancements in solar electricity production

Dye-sensitized solar cells, invented in the 1980s, use dyes designed to efficiently absorb light in the solar spectrum. The dye is mated with a semiconductor, typically titanium dioxide, that facilitates conversion of the energy in the optically excited dye into usable electrical current.

DSSCs are considered a significant advancement in photovoltaic technology since they separate the various processes of generating current from a solar cell. Michael Grätzel, a professor at the École Polytechnique Fédérale de Lausanne in Switzerland, was awarded the 2010 Millennium Technology Prize for inventing the first high-efficiency DSSC.

“If you don’t have everything in the DSSC dependent on everything else, it’s a lot easier to optimize your photovoltaic device in the most flexible and effective way,” explained Sandia senior scientist Mark Allendorf. DSSCs, for example, can capture more of the sun’s energy than silicon-based solar cells by using varied or multiple dyes and also can use different molecular systems, Allendorf said.

“It becomes almost modular in terms of the cell’s components, all of which contribute to making electricity out of sunlight more efficiently,” said Spoerke.

MOFs’ structure, versatility and porosity help overcome DSSC limitations

Though a source of optimism for the solar research community, DSSCs possess certain challenges that the Sandia research team thinks can be overcome by combining them with MOFs.

Allendorf said researchers hope to use the ordered structure and versatile chemistry of MOFs to help the dyes in DSSCs absorb more solar light, which he says is a fundamental limit on their efficiency.

“Our hypothesis is that we can put a thin layer of MOF on top of the titanium dioxide, thus enabling us to order the dye in exactly the way we want it,” Allendorf explained. That, he said, should avoid the efficiency-decreasing problem of dye aggregation, since the dye would then be locked into the MOF’s crystalline structure.

MOFs are highly-ordered materials that also offer high levels of porosity, said Allendorf, a MOF expert and 29-year veteran of Sandia. He calls the materials “Tinkertoys for chemists” because of the ease with which new structures can be envisioned and assembled. [emphasis mine]

Allendorf said the unique porosity of MOFs will allow researchers to add a second dye, placed into the pores of the MOF, that will cover additional parts of the solar spectrum that weren’t covered with the initial dye. Finally, he and Spoerke are convinced that MOFs can help improve the overall electron charge and flow of the solar cell, which currently faces instability issues.

“Essentially, we believe MOFs can help to more effectively organize the electronic and nano-structure of the molecules in the solar cell,” said Spoerke. “This can go a long way toward improving the efficiency and stability of these assembled devices.”

In addition to the Sandia team, the project includes researchers at the University of Colorado-Boulder, particularly Steve George, an expert in a thin film technology known as atomic layer deposition.

The technique, said Spoerke, is important in that it offers a pathway for highly controlled materials chemistry with potentially low-cost manufacturing of the DSSC/MOF process.

“With the combination of MOFs, dye-sensitized solar cells and atomic layer deposition, we think we can figure out how to control all of the key cell interfaces and material elements in a way that’s never been done before,” said Spoerke. “That’s what makes this project exciting.”

Here’s a picture showing an early Tinkertoy set,

Original Tinkertoy, Giant Engineer #155. Questor Education Products Co., c.1950 [downloaded from http://en.wikipedia.org/wiki/Tinkertoy#mediaviewer/File:Tinkertoy_300126232168.JPG]

Original Tinkertoy, Giant Engineer #155. Questor Education Products Co., c.1950 [downloaded from http://en.wikipedia.org/wiki/Tinkertoy#mediaviewer/File:Tinkertoy_300126232168.JPG]

The Tinkertoy entry on Wikipedia has this,

The Tinkertoy Construction Set is a toy construction set for children. It was created in 1914—six years after the Frank Hornby’s Meccano sets—by Charles H. Pajeau and Robert Pettit and Gordon Tinker in Evanston, Illinois. Pajeau, a stonemason, designed the toy after seeing children play with sticks and empty spools of thread. He and Pettit set out to market a toy that would allow and inspire children to use their imaginations. At first, this did not go well, but after a year or two over a million were sold.

Shrinky Dinks, tinkertoys, Lego have all been mentioned here in conjunction with lab work. I’m always delighted to see scientists working with or using children’s toys as inspiration of one type or another.

Swarming robot droplets

The robot droplets are a bit bigger than you might expect, the size of ping pong balls, but the idea is intriguing and for those who’ve read Michael Crichton’s book, Prey, it could seem quite disturbing (from the University of Colorado Boulder multimedia page for ‘tiny robots’),

For anyone unfamiliar with Crichton’s Prey, here’s an excerpt from the Wikipedia entry about the book which features nanobots operating as a swarm,

… As a result, hazardous elements such as the assemblers, the bacteria, and the nanobots were blown into the desert, evolving and eventually forming autonomous swarms. These swarms appear to be solar-powered and self-sufficient, reproducing and evolving rapidly. The swarms exhibit predatory behavior, attacking and killing animals in the wild, using code that Jack himself worked on. Most alarmingly, the swarms seem to possess rudimentary intelligence, the ability to quickly learn and to innovate. The swarms tend to wander around the fab plant during the day but quickly leave when strong winds blow or night falls.

The Dec. 14, 2012 posting by Alan on the Science Business website describes,

A computer science lab at University of Colorado in Boulder is building a miniature, limited-function robot designed to work in a swarm of similar devices. Computer science professor Nikolaus Correll and colleagues are building these small devices that they call droplets as building blocks for increasingly complex systems.

A University of Colorado Boulder Dec. 14, 2012 news release provides more details,

Correll and his computer science research team, including research associate Dustin Reishus and professional research assistant Nick Farrow, have developed a basic robotic building block, which he hopes to reproduce in large quantities to develop increasingly complex systems.

Recently the team created a swarm of 20 robots, each the size of a pingpong ball, which they call “droplets.” When the droplets swarm together, Correll said, they form a “liquid that thinks.”

To accelerate the pace of innovation, he has created a lab where students can explore and develop new applications of robotics with basic, inexpensive tools.

Similar to the fictional “nanomorphs” depicted in the “Terminator” films, large swarms of intelligent robotic devices could be used for a range of tasks. Swarms of robots could be unleashed to contain an oil spill or to self-assemble into a piece of hardware after being launched separately into space, Correll said.

Correll plans to use the droplets to demonstrate self-assembly and swarm-intelligent behaviors such as pattern recognition, sensor-based motion and adaptive shape change. These behaviors could then be transferred to large swarms for water- or air-based tasks.

Correll hopes to create a design methodology for aggregating the droplets into more complex behaviors such as assembling parts of a large space telescope or an aircraft.

There’s also talk about creating gardens in space,

He [Correll] also is continuing work on robotic garden technology he developed at the Massachusetts Institute of Technology in 2009. Correll has been working with Joseph Tanner in CU-Boulder’s aerospace engineering sciences department to further develop the technology, involving autonomous sensors and robots that can tend gardens, in conjunction with a model of a long-term space habitat being built by students.

Correll says there is virtually no limit to what might be created through distributed intelligence systems.

“Every living organism is made from a swarm of collaborating cells,” he said. “Perhaps some day, our swarms will colonize space where they will assemble habitats and lush gardens for future space explorers.”

The scientists don’t seem to harbour any trepidations, I guess they’re leaving that to the writers.