3 Questions for Innovating the Clean Energy Economy (MIT Energy Initiative)

Daniel Kammen, professor of energy at the University of California at Berkeley, spoke on clean energy innovation and implementation in a talk at MIT. Photo: Francesca McCaffrey/MIT Energy Initiative

Daniel Kammen of the University of California at Berkeley discusses current efforts in clean energy innovation and implementation, and what’s coming next.

Daniel Kammen is a professor of energy at the University of California at Berkeley, with parallel appointments in the Energy and Resources Group (which he chairs), the Goldman School of Public Policy, and the Department of Nuclear Science and Engineering.

Recently, he gave a talk at MIT examining the current state of clean energy innovation and implementation, both in the U.S. and internationally. Using a combination of analytical and empirical approaches, he discussed the strengths and weaknesses of clean energy efforts on the household, city, and regional levels. The MIT Energy Initiative (MITEI) followed up with him on these topics.

Q: Your team has built energy transition models for several countries, including Chile, Nicaragua, China, and India. Can you describe how these models work and how they can inform global climate negotiations like the Paris Accords?

A: My laboratory has worked with three governments to build open-source models of the current state of their energy systems and possible opportunities for improvement. This model, SWITCH , is an exceptionally high-resolution platform for examining the costs, reliability, and carbon emissions of energy systems as small as Nicaragua’s and as large as China’s. The exciting recent developments in the cost and performance improvements of solar, wind, energy storage, and electric vehicles permit the planning of dramatically decarbonized systems that have a wide range of ancillary benefits: increased reliability, improved air quality, and monetizing energy efficiency, to name just a few. With the Paris Climate Accords placing 80 percent or greater decarbonization targets on all nations’ agendas (sadly, except for the U.S. federal government), the need for an “honest broker” for the costs and operational issues around power systems is key.

Q: At the end of your talk, you mentioned a carbon footprint calculator that you helped create. How much do individual behaviors matter in addressing climate change?

A: The carbon footprint, or CoolClimate project, is a visualization and behavioral economics tool that can be used to highlight the impacts of individual decisions at the household, school, and city level. We have used it to support city-city competitions for “California’s coolest city,” to explore the relative impacts of lifetime choices (buying an electric vehicle versus or along with changes of diet), and more.

Q: You touched on the topic of the “high ambition coalition,” a 2015 United Nations Climate Change Conference goal of keeping warming under 1.5 degrees Celsius. Can you expand on this movement and the carbon negative strategies it would require?

A: As we look at paths to a sustainable global energy system, efforts to limit warming to 1.5 degrees Celsius will require not only zeroing out industrial and agricultural emissions, but also removing carbon from the atmosphere. This demands increasing natural carbon sinks by preserving or expanding forests, sustaining ocean systems, and making agriculture climate- and water-smart. One pathway, biomass energy with carbon capture and sequestration, has both supporters and detractors. It involves growing biomass, using it for energy, and then sequestering the emissions.

This talk was one in a series of MITEI seminars supported by IHS Markit.

Sugar-coated “nanosheets” selectively targets pathogens – Functions like flypaper selectively binding with viruses, bacteria, and other pathogens (Lawrence Berkeley Laboratory)

A molecular model of a peptoid nanosheet that shows loop structures in sugars (orange) that bind to Shiga toxin (shown as a five-color bound structure at upper right). Credit: Berkeley Lab

Researchers have developed a process for creating ultrathin, self-assembling sheets of synthetic materials that can function like designer flypaper in selectively binding with viruses, bacteria, and other pathogens.

In this way the new platform, developed by a team led by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), could potentially be used to inactivate or detect pathogens.

The team, which also included researchers from New York University, created the synthesized nanosheets at Berkeley Lab’s Molecular Foundry, a nanoscale science center, out of self-assembling, bio-inspired polymers known as peptoids. The study was published earlier this month in the journal ACS Nano.

The sheets were designed to present simple sugars in a patterned way along their surfaces, and these sugars, in turn, were demonstrated to selectively bind with several proteins, including one associated with the Shiga toxin, which causes dysentery. Because the outside of our cells are flat and covered with sugars, these 2-D nanosheets can effectively mimic cell surfaces.

“It’s not just a ‘lock and key’ – it’s like Velcro, with a bunch of little loops that converge on the target protein together,” said Ronald Zuckermann, a scientist at the Molecular Foundry who led the study. “Now we can mimic a nanoscale feature that is ubiquitous in biology.”

3-D-printed model of a peptoid nanosheet, showing patterned rows of sugars. Credit: Berkeley Lab

He noted that numerous pathogens, from the flu virus to cholera bacteria, bind to sugars on cell surfaces. So picking the right sugars to bind to the peptoid nanosheets, in the right distributions, can determine which pathogens will be drawn to them.

“The chemistry we’re doing is very modular,” Zuckermann added. “We can ‘click on’ different sugars, and present them on a well-defined, planar surface. We can control how far apart they are from each other. We can do this with pretty much any sugar.”

The peptoid platform is also more rugged and stable compared to natural biomolecules, he said, so it can potentially be deployed into the field for tests of bioagents by military personnel and emergency responders, for example.

And peptoids – an analog to peptides in biology that are chains of amino acids – are cheap and easy-to-make polymers.

“The chemical information that instructs the molecules to spontaneously assemble into the sugar-coated sheets is programmed into each molecule during its synthesis,” Zuckermann said. “This work demonstrates our ability to readily engineer sophisticated biomimetic nanostructures by direct control of the polymer sequence.”

A 3-D ribbon model representing a protein subunit of the Shiga toxin. The bacteria-produced toxin causes dysentery in humans. Credit: Wikimedia Commons

The sugar-coated nanosheets are made in a liquid solution. Zuckermann said if the nanosheets are used to protect someone from becoming exposed to a pathogen, he could envision the use of a nasal spray containing the pathogen-binding nanosheets.

The nanosheets could also potentially be used in environmental cleanups to neutralize specific toxins and pathogens, and the sheets could potentially be scaled to target viruses like Ebola and bacteria like E. coli, and other pathogens.

In the latest study, the researchers confirmed that the bindings with the targeted proteins were successful by embedding a fluorescent dye in the sheets and attaching another fluorescent dye on the target proteins. A color change indicated that a protein was bound to the nanosheet.

The intensity of this color change can also guide researchers to improve them, and to discover new nanosheets that could target specific pathogens.

(From phys.org)

 Explore further: ‘Molecular Velcro’ may lead to cost-effective alternatives to natural antibodies

More information: Alessia Battigelli et al, Glycosylated Peptoid Nanosheets as a Multivalent Scaffold for Protein Recognition, ACS Nano (2018). DOI: 10.1021/acsnano.7b08018

Journal reference: ACS Nano  

Provided by: Lawrence Berkeley National Laboratory

 

What Happens when Graphene is “twisted” into spirals—researchers synthesize helical nanographen – demonstrates outstanding charge and heat transport properties

This visualisation shows layers of graphene used for membranes. Credit: University of Manchester

It’s probably the smallest spring you’ve ever seen. Researchers from Kyoto University and Osaka University report for the first time in the Journal of the American Chemical Society the successful synthesis of hexa-peri-hexabenzo[7]helicene, or helical nanographene. These graphene constructs previously existed only in theory, so successful synthesis offers promising applications including nanoscale induction coils and molecular springs for use in nanomechanics.

Graphene, a hexagonal lattice of single-layer carbon atoms exhibiting outstanding charge and heat transport properties, has garnered extensive research and development interest. Helically twisted graphenes have a spiral shape. Successful synthesis of this type of graphene could have major applications, but its model compounds have never been reported. And while past research has gotten close, resulting compounds have never exhibited the expected properties.

“We processed some basic chemical compounds through step-by-step reactions, such as McMurry coupling, followed by stepwise photocyclodehydrogenation and aromatization,” explains first author Yusuke Nakakuki. “We then found that we had synthesized the foundational backbone of helical graphene.”

The team confirmed the helicoid nature of the structure through X-ray crystallography, also finding both clockwise and counter-clockwise nanographenes. Further tests showed that the electronic structure and photoabsorption properties of this compound are much different from previous ones. “This helical nanographene is the first of its kind,” concludes lead author Kenji Matsuda. “We will try to expand their surface area and make the helices longer. I expect to find many new physical properties as well.”

The paper, titled “Hexa-peri-hexabenzo[7]helicene: Homogeneously π-Extended Helicene as a Primary Substructure of Helically Twisted Chiral Graphenes,” appeared 19 March 2018 in the Journal of the American Chemical Society.

(From Phys.org)

 Explore further: Synthesis of a water-soluble warped nanographene and its application for photo-induced cell death

More information: Yusuke Nakakuki et al, Hexa-peri-hexabenzo[7]helicene: Homogeneously π-Extended Helicene as a Primary Substructure of Helically Twisted Chiral Graphenes, Journal of the American Chemical Society (2018). DOI: 10.1021/jacs.7b13412

Journal reference: Journal of the American Chemical Society 

MIT: Finding a New Way to Design and Analyze Better Battery Materials: Discoveries could accelerate the development of high-energy lithium batteries

Diagram illustrates the crystal lattice of a proposed battery electrolyte material called Li3PO4. The researchers found that measuring how vibrations of sound move through the lattice could reveal how well ions – electrically charged atoms or molecules – could travel through the solid material, and therefore how they would work in a real battery. In this diagram, the oxygen atoms are shown in red, the purple pyramid-like shapes are phosphate (PO4) molecules. The orange and green spheres are ions of lithium.
Image: Sokseiha Muy

Design principles could point to better electrolytes for next-generation lithium batteries.

A new approach to analyzing and designing new ion conductors — a key component of rechargeable batteries — could accelerate the development of high-energy lithium batteries and possibly other energy storage and delivery devices such as fuel cells, researchers say.

The new approach relies on understanding the way vibrations move through the crystal lattice of lithium ion conductors and correlating that with the way they inhibit ion migration. This provides a way to discover new materials with enhanced ion mobility, allowing rapid charging and discharging.

At the same time, the method can be used to reduce the material’s reactivity with the battery’s electrodes, which can shorten its useful life. These two characteristics — better ion mobility and low reactivity — have tended to be mutually exclusive.

The new concept was developed by a team led by W.M. Keck Professor of Energy Yang Shao-Horn, graduate student Sokseiha Muy, recent graduate John Bachman PhD ’17, and Research Scientist Livia Giordano, along with nine others at MIT, Oak Ridge National Laboratory, and institutions in Tokyo and Munich. Their findings were reported in the journal Energy and Environmental Science.

The new design principle has been about five years in the making, Shao-Horn says. The initial thinking started with the approach she and her group have used to understand and control catalysts for water splitting, and applying it to ion conduction — the process that lies at the heart of not only rechargeable batteries, but also other key technologies such as fuel cells and desalination systems.

While electrons, with their negative charge, flow from one pole of the battery to the other (thus providing power for devices), positive ions flow the other way, through an electrolyte, or ion conductor, sandwiched between those poles, to complete the flow.

Typically, that electrolyte is a liquid. A lithium salt dissolved in an organic liquid is a common electrolyte in today’s lithium-ion batteries. But that substance is flammable and has sometimes caused these batteries to catch fire. The search has been on for a solid material to replace it, which would eliminate that issue.

A variety of promising solid ion conductors exist, but none is stable when in contact with both the positive and negative electrodes in lithium-ion batteries, Shao-Horn says.

Therefore, seeking new solid ion conductors that have both high ion conductivity and stability is critical. But sorting through the many different structural families and compositions to find the most promising ones is a classic needle in a haystack problem. That’s where the new design principle comes in.

The idea is to find materials that have ion conductivity comparable to that of liquids, but with the long-term stability of solids. The team asked, “What is the fundamental principle? What are the design principles on a general structural level that govern the desired properties?” Shao-Horn says. A combination of theoretical analysis and experimental measurements has now yielded some answers, the researchers say.

“We realized that there are a lot of materials that could be discovered, but no understanding or common principle that allows us to rationalize the discovery process,” says Muy, the paper’s lead author. “We came up with an idea that could encapsulate our understanding and predict which materials would be among the best.”

The key was to look at the lattice properties of these solid materials’ crystalline structures. This governs how vibrations such as waves of heat and sound, known as phonons, pass through materials. This new way of looking at the structures turned out to allow accurate predictions of the materials’ actual properties. “Once you know [the vibrational frequency of a given material], you can use it to predict new chemistry or to explain experimental results,” Shao-Horn says.

The researchers observed a good correlation between the lattice properties determined using the model and the lithium ion conductor material’s conductivity. “We did some experiments to support this idea experimentally” and found the results matched well, she says.

They found, in particular, that the vibrational frequency of lithium itself can be fine-tuned by tweaking its lattice structure, using chemical substitution or dopants to subtly change the structural arrangement of atoms.

The new concept can now provide a powerful tool for developing new, better-performing materials that could lead to dramatic improvements in the amount of power that could be stored in a battery of a given size or weight, as well as improved safety, the researchers say.

Already, they used the method to find some promising candidates. And the techniques could also be adapted to analyze materials for other electrochemical processes such as solid-oxide fuel cells, membrane based desalination systems, or oxygen-generating reactions.

The team included Hao-Hsun Chang at MIT; Douglas Abernathy, Dipanshu Bansal, and Olivier Delaire at Oak Ridge; Santoshi Hori and Ryoji Kanno at Tokyo Institute of Technology; and Filippo Maglia, Saskia Lupart, and Peter Lamp at Research Battery Technology at BMW Group in Munich.

The work was supported by BMW, the National Science Foundation, and the U.S. Department of Energy.

Watch a YouTube Video on New Nano-Enabled Super Capacitors and Batteries

Is This the Battery Boost We’ve Been Waiting For?

Electric cars are among the products that stand to benefit from new lithium-ion cells that could store as much as 40% more energy. A BMW i Vision Dynamics concept electric automobile, made by BMW AG, on display in September. PHOTO: SIMON DAWSON/BLOOMBERG

The batteries that power our modern world—from phones to dronesto electric cars—will soon experience something not heard of in years: Their capacity to store electricity will jump by double-digit percentages, according to researchers, developers and manufacturers.

The next wave of batteries, long in the pipeline, is ready for commercialization. This will mean, among other things, phones with 10% to 30% more battery life, or phones with the same battery life but faster and lighter or with brighter screens. We’ll see more cellular-connected wearables. As this technology becomes widespread, makers of electric vehicles and home storage batteries will be able to knock thousands of dollars off their prices over the next five to 10 years. Makers of electric aircraft will be able to explore new designs.

There is a limit to how far lithium-ion batteries can take us; surprisingly, it’s about twice their current capacity. The small, single-digit percentage improvements we see year after year typically are because of improvements in how they are made, such as small tweaks to their chemistry or new techniques for filling battery cells with lithium-rich electrolyte. What’s coming is a more fundamental change to the materials that make up a battery.

Equipment that Sila Nanotechnologies uses to manufacture material for lithium-silicon batteries. PHOTO: SILA NANOTECHNOLOGIES

 

First, some science: Every lithium-ion battery has an anode and a cathode. Lithium ions traveling between them yield the electrical current that powers our devices. When a battery is fully charged, the anode has sucked up lithium ions like a sponge. And as it discharges, those ions travel through the electrolyte, to the cathode.

Typically, anodes in lithium-ion batteries are made of graphite, which is carbon in a crystalline form. While graphite anodes hold a substantial number of lithium ions, researchers have long known a different material, silicon, can hold 25 times as many.

The trick is, silicon brings with it countless technical challenges. For instance, a pure silicon anode will soak up so many lithium ions that it gets “pulverized” after a single charge, says George Crabtree, director of the Joint Center for Energy Storage Research, established by the U.S. Department of Energy at the University of Chicago Argonne lab to accelerate battery research.

Current battery anodes can have small amounts of silicon, boosting their performance slightly. The amount of silicon in a company’s battery is a closely held trade secret, but Dr. Crabtree estimates that in any battery, silicon is at most 10% of the anode. In 2015, Tesla founder Elon Musk revealed that silicon in the Panasonic-made batteries of the auto maker’s Model S helped boost the car’s range by 6%.

Now, some startups say they are developing production-ready batteries with anodes that are mostly silicon. Sila Nanotechnologies,Angstron Materials , Enovix and Enevate, to name a few, offer materials for so-called lithium-silicon batteries, which are being tested by the world’s largest battery manufacturers, car companies and consumer-electronics companies.

Prototype batteries built at Sila with the startup’s silicon-dominant anode technology. PHOTO: SILA NANOTECHNOLOGIES

For Sila, in Alameda, Calif., the secret is nanoparticles lots of empty space inside. This way, the lithium can be absorbed into the particle without making the anode swell and shatter, says Sila Chief Executive Gene Berdichevsky. Cells made with Sila’s particles could store 20% to 40% more energy, he adds.

Angstron Materials, in Dayton, Ohio, makes similar claims about its nanoparticles for lithium-ion batteries.

Dr. Crabtree says this approach is entirely plausible, though there’s a trade-off: By allowing more room inside the anode for lithium ions, manufacturers must produce a larger anode. This anode takes up more space in the battery, allowing less overall space to increase capacity. This is why the upper bound of increased energy density using this approach is about 40%.

The big challenge, as ever, is getting to market, says Dr. Crabtree.

Sila’s clients include BMW and Amperex Technology , one of the world’s largest makers of batteries for consumer electronics, including both Apple ’s iPhone and Samsung ’s Galaxy S8 phone.

China-based Amperex is also an investor in Sila, but Amperex Chief Operating Officer Joe Kit Chu Lam says his company is securing several suppliers of the nanoparticles necessary to produce lithium-silicon batteries. Having multiple suppliers is essential for securing enough volume, he says.

This nanoparticle of carbon and silicon, made by Global Graphene Group, could help lithium-ion batteries store significantly more energy. PHOTO: GLOBAL GRAPHENE GROUP

The first commercial consumer devices to have higher-capacity lithium-silicon batteries will likely be announced in the next two years, says Mr. Lam, who expects a wearable to be first. Other companies claim a similar timetable for consumer rollout.

Enevate produces complete silicon-dominant anodes for car manufacturers. CEO Robert Rango says its technology increases the range of electric vehicles by 30% compared with conventional lithium-ion batteries.

BMW plans to incorporate Sila’s silicon anode technology in a plug-in electric vehicle by 2023, says a company spokesman. BMW expects an increase of 10% to 15% in battery-pack capacity in a single leap. While this is the same technology destined for mobile electronics, the higher volumes and higher safety demands of the auto industry mean slower implementation there. In 2017, BMW said it would invest €200 million ($246 million) in its own battery-research center.

Enovix, whose investors include Intel and Qualcomm, has pioneered a different kind of 3-D structure for its batteries, says CEO Harrold Rust. With much higher energy density and anodes that are almost pure silicon, the company claims its batteries would contain 30% to 50% more energy in the size needed for a mobile phone, and two to three times as much in the size required for a smartwatch.

The downside: producing these will require a significant departure from the current manufacturing process.

Even though it’s a significant advance, to get beyond what’s possible with lithium-silicon batteries will require a change in battery composition—such as lithium-sulfur chemistry or solid-state batteries. Efforts to make these technologies viable are at a much earlier stage, however, and it isn’t clear when they’ll arrive.

Meanwhile, we can look forward to the possibility of a thinner or more capable Apple Watch, wireless headphones we don’t have to charge as often and electric vehicles that are actually affordable. The capacity of lithium-ion batteries has increased threefold since their introduction in 1991, and at every level of improvement, new and unexpected applications, devices and business opportunities pop up.

 

Corrections & Amplifications 

Sila Nanotechnologies produces nanoparticles that contain silicon and other components, but don’t include graphite. A previous version of this column incorrectly described nanoparticles as a graphite-silicon composite. An earlier version also incorrectly identified Angstron Materials as Angstrom Materials. (Angstron error corrected: March 18, 2018. Nanoparticles error corrected: March 19, 2018

 

Appeared in the March 19, 2018, print edition as ‘Battery Life Powers Ahead Toward Sizable Gains.’

Have you seen Tenka Energy’s YouTube Video?  Watch Here:

NEWT – Mat baits, hooks and destroys pollutants in water: Rice University

Specks of titanium dioxide adhere to polyvinyl fibers in a mat developed at the Rice University-led NEWT Center to capture and destroy pollutants from wastewater or drinking water. After the mat attracts and binds pollutants, the titanium dioxide photocatalyst releases reactive oxygen species that destroy them. Credit: Rice University/NEWT

A polymer mat developed at Rice University has the ability to fish biologically harmful contaminants from water through a strategy known as “bait, hook and destroy.”

Tests with wastewater showed the mat can efficiently remove targeted pollutants, in this case a pair of biologically harmful endocrine disruptors, using a fraction of the energy required by other technology. The technique can also be used to treat drinking water.

The mat was developed by scientists with the Rice-led Nanotechnology-Enabled Water Treatment (NEWT) Center. The research is available online in the American Chemical Society journal Environmental Science and Technology.

The mat depends on the ability of a common material, titanium dioxide, to capture pollutants and, upon exposure to light, degrade them through oxidation into harmless byproducts.

Titanium dioxide is already used in some wastewater treatment systems. It is usually turned into a slurry, combined with wastewater and exposed to ultraviolet light to destroy contaminants. The slurry must then be filtered from the water.

The NEWT mat simplifies the process. The mat is made of spun polyvinyl fibers. The researchers made it highly porous by adding small plastic beads that were later dissolved with chemicals. The pores offer plenty of surface area for titanium oxide particles to inhabit and await their prey.

The mat’s hydrophobic (water-avoiding) fibers naturally attract hydrophobic contaminants like the endocrine disruptors used in the tests. Once bound to the mat, exposure to light activates the photocatalytic titanium dioxide, which produces reactive oxygen species (ROS) that destroy the contaminants.

Established by the National Science Foundation in 2015, NEWT is a national research center that aims to develop compact, mobile, off-grid water-treatment systems that can provide clean water to millions of people who lack it and make U.S. energy production more sustainable and cost-effective.

NEWT researchers said their mat can be cleaned and reused, scaled to any size, and its chemistry can be tuned for various pollutants.

“Current photocatalytic treatment suffers from two limitations,” said Rice environmental engineer and NEWT Center Director Pedro Alvarez. “One is inefficiency because the oxidants produced are scavenged by things that are much more abundant than the target pollutant, so they don’t destroy the pollutant.

The Rice University-led NEWT Center created a nanoparticle-infused polymer mat that both attracts and destroys pollutants in wastewater or drinking water. A mat, top left, is immersed in water with methylene blue as a contaminant. The contaminant is then absorbed at top right by the mat and, in the bottom images, destroyed by exposure to light. The mat is then ready for reuse. Credit: Rice University/NEWT

“Second, it costs a lot of money to retain and separate slurry photocatalysts and prevent them from leaking into the treated water,” he said. “In some cases, the energy cost of filtering that slurry is more than what’s needed to power the UV lights.

“We solved both limitations by immobilizing the catalyst to make it very easy to reuse and retain,” Alvarez said. “We don’t allow it to leach out of the mat and impact the water.”

Alvarez said the porous polymer mat plays an important role because it attracts the target pollutants. “That’s the bait and hook,” he said. “Then the photocatalyst destroys the pollutant by producing hydroxyl radicals.”

“The nanoscale pores are introduced by dissolving a sacrificial polymer on the electrospun fibers,” lead author and former Rice postdoctoral researcher Chang-Gu Lee said. “The pores enhance the contaminants’ access to titanium dioxide.”

The experiments showed dramatic energy reduction compared to wastewater treatment using slurry.

“Not only do we destroy the pollutants faster, but we also significantly decrease our electrical energy per order of reaction,” Alvarez said. “This is a measure of how much energy you need to remove one order of magnitude of the pollutant, how many kilowatt hours you need to remove 90 percent or 99 percent or 99.9 percent.

“We show that for the slurry, as you move from treating distilled water to wastewater treatment plant effluent, the amount of energy required increases 11-fold. But when you do this with our immobilized bait-and-hook photocatalyst, the comparable increase is only two-fold. It’s a significant savings.”

The mat also would allow treatment plants to perform pollutant removal and destruction in two discrete steps, which isn’t possible with the slurry, Alvarez said. “It can be desirable to do that if the water is murky and light penetration is a challenge. You can fish out the contaminants adsorbed by the mat and transfer it to another reactor with clearer water. There, you can destroy the pollutants, clean out the mat and then return it so it can fish for more.”

Tuning the mat would involve changing its hydrophobic or hydrophilic properties to match target pollutants. “That way you could treat more water with a smaller reactor that is more selective, and therefore miniaturize these reactors and reduce their carbon footprints,” he said. “It’s an opportunity not only to reduce energy requirements, but also space requirements for photocatalytic water treatment.”

Alvarez said collaboration by NEWT’s research partners helped the project come together in a matter of months. “NEWT allowed us to do something that separately would have been very difficult to accomplish in this short amount of time,” he said.

“I think the mat will significantly enhance the menu from which we select solutions to our water purification challenges,” Alvarez said.

More information: Chang-Gu Lee et al, Porous electrospun fibers embedding TiO2 for adsorption and photocatalytic degradation of water pollutants, Environmental Science & Technology (2018). DOI: 10.1021/acs.est.7b06508

Provided by Rice University

Explore further:Researchers turn plastic pollution into cleaners

University of Delaware: Programming DNA to deliver cancer drugs

DNA has an important job — it tells your cells which proteins to make. Now, a research team at the University of Delaware has developed technology to program strands of DNA into switches that turn proteins on and off. Credit: University of Delaware

DNA has an important job—it tells your cells which proteins to make. Now, a research team at the University of Delaware has developed technology to program strands of DNA into switches that turn proteins on and off.

UD’s Wilfred Chen Group describes their results in a paper published Monday, March 12 in the journal Nature Chemistry. This technology could lead to the development of new cancer therapies and other drugs.

Computing with DNA

This project taps into an emerging field known as DNA computing. Data we commonly send and receive in everyday life, such as text messages and photos, utilize binary code, which has two components—ones and zeroes. DNA is essentially a code with four components, the nucleotides guanine, adenine, cytosine, and thymine. In cells, the arrangement of these four nucleotides determines the output—the proteins made by the DNA. Here, scientists have repurposed the DNA code to design logic-gated DNA circuits.

“Once we had designed the system, we had to first go into the lab and attach these DNA strands to various proteins we wanted to be able to control,” said study author Rebecca P. Chen, a doctoral student in chemical and biomolecular engineering (no relation to Wilfred Chen).

The custom sequence designed DNA strands were ordered from a manufacturer while the proteins were made and purified in the lab. Next, the protein was attached to the DNA to make protein-DNA conjugates.

The group then tested the DNA circuits on E. coli bacteria and human cells. The target proteins organized, assembled, and disassembled in accordance with their design.

“Previous work has shown how powerful DNA nanotechnology might possibly be, and we know how powerful proteins are within cells,” said Rebecca P. Chen. “We managed to link those two together.”

Applications to drug delivery

The team also demonstrated that their DNA-logic devices could activate a non-toxic cancer prodrug, 5-fluorocytosine, into its toxic chemotherapeutic form, 5-fluorouracil. Cancer prodrugs are inactive until they are metabolized into their therapeutic form.

In this case, the scientists designed DNA circuits that controlled the activity of a protein that was responsible for conversion of the prodrug into its active form. The DNA circuit and protein activity was turned “on” by specific RNA/DNA sequence inputs, while in the absence of said inputs the system stayed “off.”

To do this, the scientists based their sequence inputs on microRNA, small RNA molecules that regulate cellular gene expression. MicroRNA in cancer cells contains anomalies that would not be found in healthy cells. For example, certain microRNA are present in cancer cells but absent in healthy cells. The group calculated how nucleotides should be arranged to activate the cancer prodrug in the presence of cancer microRNA, but stay inactive and non-toxic in a non-cancerous environment where the microRNA are missing.

When the cancer microRNAs were present and able to turn the DNA circuit on, cells were unable to grow. When the circuit was turned off, cells grew normally.

Wilfred Chen (left) and Rebecca P. Chen are developing new biomolecular tools to address key global health problems. Credit: University of Delaware/ Evan Krape

This technology could have wide applications not only to other diseases besides cancer, but also beyond the biomedical field. For example, the research team demonstrated that their technology could be applied to the production of biofuels, by utilizing their technology to guide an enzymatic cascade, a series of chemical reactions, to break down a plant fiber.

Using the newly developed technology, researchers could target any DNA sequence of their choosing and attach and control any protein they want. Someday, researchers could “plug and play” programmed DNA into a variety of cells to address a variety of diseases, said study author Wilfred Chen, Gore Professor of Chemical Engineering.

“This is based on a very simple concept, a logical combination, but we are the first to make it work,” he said. “It can address a wide scope of problems, and that makes it very intriguing.”

More information: Rebecca P. Chen et al, Dynamic protein assembly by programmable DNA strand displacement, Nature Chemistry (2018). DOI: 10.1038/s41557-018-0016-9

Provided by: University of Delaware

Why Your EV Battery Will Last Longer than Your Mobile Phone Battery

How Usage and Management Affect Longevity

Car makers are extending the driving range of the electric vehicle to resemble a gasoline-powered car. This requires larger batteries that grow exponentially with the distance driven. Figure 1 illustrates the estimated driving ranges with different battery systems and hydrogen as a function of size.

Doubling battery size does not extend the driving range linearly and the vehicle becomes inefficient with increasing weight. Li-ion performs better than lead acid in energy density, but no battery meets hydrogen with a fuel cell, or fossil fuel feeding the traditional internal combustion engine (not shown). Extending the driving range with a larger tank is almost negligible compared to oversizing a battery.

There is a threshold as to battery size and weight in a vehicle; going beyond a critical point has a negative return. The vehicle becomes environmentally unsustainable.

Figure 1: Battery size as a function of driving range.

Oversizing the battery does not expand the driving range linearly.

Note: 35MPa hydrogen tank refers to 5,000psi.

Source:  International Journal of Hydrogen Energy, 34, 6005-6020 (2009)

Batteries have low calorific value compared to fossil fuel and it makes little sense to power a freight train, ocean-going ship or large airplane with batteries. A study reveals that replacing kerosene with batteries could keep an aircraft airborne for less than 10 minutes. Cost is another issue and batteries take long to charge. A fill-up that is quickly and conveniently as topping a tank with liquid or gaseous fuel is impossible with an electrochemical device.

Charging also needs high power. An ultra-fast EV charge draws the equivalent electrical power of five households. Charging a fleet of EVs could dim a city.

Conversely, fossil fuel cannot match the qualities of a battery that is clean, quiet, and has an instant start-up with the flick of a switch. Although fossil fuel is cheap and readily available, frivolous burning of this resource must stop to save our planet. Finding alternatives that are environmentally friendly, economical and durable is a challenge; the battery fills this requirement only in part.

Advancements made in battery technology in the last 20 years are insufficient to replace fossil fuel. Pushing the boundaries of the battery reminds us of its many limitations, which include low energy density; long charging times, high cost and a short life before the packs quits, often without warning. Table 2 illustrates the energy densities of common fuels, including the battery.

Fuel – Energy by mass (Wh/kg)

Hydrogen (350 bar)

39,300

Gasoline, diesel, natural gas (250 bar)

12,000–13,000

Body fat

10,500

Black coal (solid), Methanol

6,000–7,000

Wood (average)

2,300

Lithium-ion battery

100–250

Lead acid battery

40

Compressed air

34

Supercapacitor

5

Table 2: Energy densities of fossil fuel and batteries.

Fossil fuel carries many times the energy per mass compared to batteries, but electrical power can be utilized more efficiently than burning fossil fuel.

Compiled from various sources. Values are approximate

Fossil fuel carries many times the energy per mass compared to batteries, but electrical power can be utilized more efficiently than burning fossil fuel.

Compiled from various sources. Values are approximate.

How to Prolong Battery Life

Driving range is a key consideration when buying an EV. Cost also plays a role but seldom is battery life mentioned. This may not be the concern for a tire-kicker, nor does the salesman want to alarm the buyer of possible service issues later on. What sells is the joy of electric propulsion that is clean, quiet and exhilarating. Taxpayer subsidies also help.

Batteries have a defined life span and this is apparent with the decreasing runtime in our mobile phones. EV advocates may argue that a smartphone battery cannot be compared to an EV battery; these products are totally different.

That is true, but ironically both use lithium-ion systems. This article looks at the battery in an EV and mobile phone in terms of runtime and longevity.

The battery in the mobile phone is consumer grade, optimized for maximum runtime at low cost. the EV battery, on the other hand, is made to industry standards with longevity in mind. The dissimilarities do not stop there and a key difference is how the energy is dispensed.

A mobile phone gets charged at the end of a day and the stored energy can be fully utilized until the battery goes empty. In other words, the user has full access to the stored energy. When the battery is new, the phone provides good runtimes but this decreases with use. In this full cycle mode, Li-ion delivers about 500 cycles.

The user adjusts to the decreasing runtime, and being a consumer product, the end of battery life often corresponds with a broken screen or the introduction of a new model. Built-in obsolescence serves well for device manufacturers and retailers.

The EV battery also ages and the capacity fades, but the EV manufacturer must guarantee the battery for eight years. This is done by oversizing the battery. When the battery is new, only about half of the available energy is utilized. This is done by charging the pack to only 80% instead of a full charge, and discharging to 30% when the available driving range is spent. As the battery fades, more of the battery storage is demanded. The driving range stays constant but unknown to the driver, the battery is gradually charged to a higher level and discharged deeper to compensate for the fade.

Once the battery capacity has dropped to 80%, the oversize protection is consumed and the battery maintenance system (BMS) applies a full charge and discharge. This exposes the EV battery to a similar stress level of a mobile phone and the driver begins noticing reduced driving range. Battery replacement may become necessary but the cost will be steep and higher than a combustion engine.

The EV begins to impersonate a mobile phone in terms of obsolescence when the battery fades. This may be the time when the buyer is flooded with faster and flashier models; something the smartphone user is all too familiar with, but price will be the shocker. It’s still too early to tell how long an EV battery will last. Some say the battery will outlive the car and find secondary application in energy storage systems.

Driving habits and temperature also affects aging, a characteristic that came to light when EV batteries operating in a warm climate faded prematurely. It was learned that keeping a battery at elevated temperature and high state-of-charge causes more stress than aggressive driving. In other words, keeping a fully charged Li-ion at 30°C (86°F) and above hastens the aging process more than driving at a moderate temperature. Many EV batteries include liquid cooling to reduce heat-related battery fade.

Harsh loading also reduces battery life. Because of its large size, the EV battery is only being stressed moderately, even during acceleration. In comparison, the mobile phone draws continuous high current from a small battery when transmitting and crunching data. This puts more stress on a mobile phone battery than driving an EV. A battery is also negatively impacted by the pulsed load of a mobile phone rather than the DC load of an EV. (See BU-501: Basic about Discharging.)

The EV does not disclose the battery capacity to the driver and only reveals state-of-charge (SoC) in the form of driving range. This is done in part for fear of customer complaints should the capacity drop below the mandated level at the end of the warranty period. Less knowledge is often better. The same restriction applies to a mobile phone battery, although access codes for service personnel are often available. A new battery has (should have) a capacity of 100%; 80% is the typical end of battery life.

Dynamic Stress Tests (DST) on Li-ion

All Li-ion batteries fade with time and use, whether in consumer products or enduring industrial use. Figure 3 explores the longevity of Li-ion batteries with different charge and discharge end points.

Figure 3: Capacity loss of Li-ion as a function of charge and discharge cut-off points.

Limiting a full charge and discharge prolongs battery life but lowers utilization.

Source: ResearchGate – Modeling of Lithium-Ion Battery Degradation for Cell Life Assessment.  ResearchGate is a social networking site for scientists and researchers founded in 2008 to share papers, ask and answer questions, and to find collaborators.

The Li-ion batteries in the above table perform well but the largest capacity loss occurs with the pack that is charged to 100% and discharged to 25% (black stars). Cycling between 85% and 25% (green) provides longer service life than charging to 100% and discharging to 50% (dark blue).

The lowest capacity loss occurs when charging Li-ion to 75% and discharging to 65%. This, however, takes oversizing to the extreme and the battery is underutilized. Such practice is applied in satellites to achieve high cycle life and less for terrestrial applications as it increases cost, size and weight beyond a reasonable point of return. The dynamic stress test does not include a battery that is charged to 100% and discharged to zero, as is the case with a mobile phone. A full cycle provides the best battery utilization but reduces longevity.

Batteries tested in a laboratory do not always replicate true life conditions, and the results tend to be better than experienced in field use. In a lab environment, batteries are cycled over a period of a few months, often at controlled temperature and with an ideal charge and discharge regime. Random usage in real life adds the exposure to heat, vibration and harsh charging practices.

Summary

Batteries do not have a fixed life span, nor do they die suddenly but fade gradually. Environmental conditions, and not cycling alone, govern longevity. The user has some control to prolong battery life by avoiding ultra-fast charges, operating at moderate temperature and avoiding full charges. Avoiding harsh loads and full discharges also helps. Heat is the enemy of most batteries and the worst condition is keeping a fully charged Li-ion battery at elevated temperatures. Even with the best of care, a battery only lives for a season and the pack will eventually face retirement when power fades.

About the Author

Isidor Buchmann is the founder and CEO of Cadex Electronics Inc. For three decades, Buchmann has studied the behavior of rechargeable batteries in practical, everyday applications, has written award-winning articles including the best-selling book “Batteries in a Portable World,” now in its fourth edition. Cadex specializes in the design and manufacturing of battery chargers, analyzers and monitoring devices. For more information on batteries, visit www.batteryuniversity.com; product information is on www.cadex.com.

Is It Possible? Will You Soon be Able to Replace Your Glasses And Contacts With Nanoparticle Eyedrops?

A revolutionary, cutting-edge technology, developed by researchers at Bar-Ilan University’s Institute of Nanotechnology and Advanced Materials (BINA), has the potential to provide a new alternative to eyeglasses, contact lenses, and laser correction for refractive errors.

The technology, known as Nano-Drops, was developed by Dr. David Smadja (Ophthalmologist from Shaare Zedek Medical Center), Prof. Zeev Zalevsky, from Bar-Ilan’s Kofkin Faculty of Engineering, and Prof. Jean-Paul Moshe Lellouche, Head of the Department of Chemistry at Bar-Ilan. A related patent on this new invention was recently filed by Birad – Research & Development Company Ltd., the commercializing company of Bar-Ilan University.

Nano-Drops achieve their optical effect and correction by locally modifying the corneal refractive index. The magnitude and nature of the optical correction is adjusted by an optical pattern that is stamped onto the superficial layer of the corneal epithelium with a laser source. The shape of the optical pattern can be adjusted for correction of myopia (nearsightedness), hyperopia (farsightedness) or presbyopia (loss of accommodation ability). The laser stamping onto the cornea takes a few milliseconds and enables the nanoparticles to enhance and ‘activate’ this optical pattern by locally changing the refractive index and ultimately modifying the trajectory of light passing through the cornea.

The laser stamping source does not relate to the commonly known ‘laser treatment for visual correction’ that ablates corneal tissue. It is rather a small laser device that can connect to a smartphone and stamp the optical pattern onto the corneal epithelium by placing numerous adjacent pulses in a very speedy and painless fashion.  Tiny corneal spots created by the laser allow synthetic and biocompatible nanoparticles to enter and locally modify the optical power of the eye at the desired correction.

In the future this technology may enable patients to have their vision corrected in the comfort of their own home. To accomplish this, they would open an application on their smartphone to measure their vision, connect the laser source device for stamping the optical pattern at the desired correction, and then apply the Nano-Drops to activate the pattern and provide the desired correction.

Upcoming in-vivo experiments in rabbits will allow the researchers to determine how long the effect of the Nano-Drops will last after the initial application. Meanwhile, this promising technology has been shown, through ex-vivo experiments, to efficiently correct nearly 3 diopters of both myopia and presbyopia in pig eyes.

Bar-Ilan University, founded in 1955, was one of the first comprehensive research universities to be established in Israel.  From 70 students to 17,000, its milestone achievements in the sciences and humanities have made an indelible imprint on the landscape of the nation.  The university has 8 faculties, four of which focus on STEM research. They include Medicine, Exact Sciences (Physics, Chemistry, Computer Science, Biophysics and Mathematics), Life Sciences and Engineering.

Bar-Ilan University

MIT: Device makes power conversion more efficient New design could dramatically cut energy waste in electric vehicles, data centers, and the power grid

Genesis Nanotechnologyo and l o

MIT postdoc Yuhao Zhang, handles a wafer with hundreds of vertical gallium nitride power devices fabricated from the Microsystems Technology Laboratories production line. Courtesy of Yuhao Zhang

Power electronics, which do things like modify voltages or convert between direct and alternating current, are everywhere. They’re in the power bricks we use to charge our portable devices; they’re in the battery packs of electric cars; and they’re in the power grid itself, where they mediate between high-voltage transmission lines and the lower voltages of household electrical sockets.

Power conversion is intrinsically inefficient: A power converter will never output quite as much power as it takes in. But recently, power converters made from gallium nitride have begun to reach the market, boasting higher efficiencies and smaller sizes than conventional, silicon-based power converters.

Commercial gallium nitride power devices can’t handle voltages above about 600 volts, however, which limits their use to household…

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