U of Maryland: Wang Group Develops Highly Reversible 5.3 V Battery ~ 720Wh/kg for 1k cycles ~ With graphite and Li-metal anodes ~ Game Changer?


news story image

Over the last several years, increasing the energy density of batteries has been a top priority in battery technology development, congruent with increasing demands for faster mobile devices and longer-lasting electrIc vehicles.

The energy density of lithium-ion batteries can be enhanced by either increasing the capacity of electrodes, or by enhancing the cell voltage (V).

Extensive research has been devoted to exploring the pairing of various materials in the search for the most efficient cathode/anode mix, but until now, only limited advances have been achieved due to the narrow electrochemical stability window of traditional electrolyte.

Researchers at the University of Maryland (UMD) led by Chunsheng Wang – a professor with joint appointments in the Departments of Chemical & Biomolecular Engineering (ChBE), and Chemistry & Biochemistry – have developed a highly reversible 5.3 V battery offering a Mn3+-free LiCoMnO4 cathode, and graphite and Li-metal anodes.

A specially designed electrolyte was also created, which is stable to 5.5V for both the LiCoMnO4 cathode and (graphite and Li-metal) anodes. This resulted in a 5.3V Li-metal cell, delivering a high energy density of 720Wh/kg for 1k cycles.

What’s more, this battery chemistry boasts a Coulombic efficiency of >99%, offering new development opportunity for high-voltage and energy Li-ion batteries.

Long Chen – a ChBE post-doctoral research associate – and Xiulin Fan– a ChBE assistant research scientist – served as first authors on the corresponding research paper, published in Chem on February 28, 2019.

“We are pleased to announce that we have created a stable 5.3V battery,” said Long Chen.

“The key is the super electrolytes with an especially wide electrochemical windows of 0 – 5.5V – this is due to the formation of robust interfacial layer on the electrodes.”   

Said Wang, “The high voltage electrolytes enable us to use high voltage cathode and high capacity Si- and potential Li-metal anodes, which will significantly increase the cell energy density.

However, the Coulombic efficiency of >99% for 5.3V LiCoMnO4 still needs improvement to achieve a long cycle life.”

For additional information:

Chen, L., Fa, X., Hu, E., Ji, X., Chen, J., HouS., Deng, T., Li, J., Su, D., Yang, X., Wang, C. “Achieving High Energy Density through Increasing the Output Voltage:

A Highly Reversible 5.3 V Battery.” Chem, 28 February 2019. https://doi.org/10.1016/j.chempr.2019.02.003

Published March 6, 2019

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Everybody Wants EV Charging Stations ~ Almost Nobody Wants to Build Them – Why?


 

MT Highway 1 images

         A Lonely Stretch of Highway in Wyoming

A driver planning to make the trek from Denver to Salt Lake City can look forward to an eight-hour trip across some of the most beautiful parts of the country, long stretches with nary a town in sight. The fastest route would take her along I-80 through southern Wyoming. For 300 miles between Laramie and Evanston, she would see, according to a rough estimate, no fewer than 40 gas stations where she could fuel up her car. But if she were driving an electric vehicle, she would see just four charging stations where she could recharge her battery.

The same holds true across the country. Gas stations outnumber public charging stations by around seven to one. It’s no wonder people get so nervous about driving an electric car.

EV charge 1 images

Numerous studies have shown that consumers steer clear of EVs because they worry about the lack of charging stations. Studies also show that consumers are more likely to buy an electric car when they see stations around town. While fears about range anxiety are largely unfounded — even the cheapest EVs sport enough range to serve nearly all of a driver’s needs — the paucity of charging stations is a real concern on longer trips, and it is deterring consumers from going all-electric.

To be clear, it’s not just consumers who want to see more chargers. Charging stations are a boon to automakers, who want to sell electric cars, as well as to power utilities, who want to sell more electricity. Some utilities and automakers are investing huge sums into setting up charging stations — including Volkswagen’s commitment to spend $2 billion on EV charging infrastructure as part of their settlement over the diesel emissions scandal. But by and large, automakers and power companies are not putting a lot of money towards charging infrastructure.

“I think the biggest problem with charging stations is there is no one responsible for installing charging stations,” said Nick Sifuentes, executive director at Tri-State Transportation Campaign. “So you see some automakers, like Tesla, installing charging stations. You see charging stations occasionally getting put out as part of a municipal planning process,” he said, “but for the most part, there is no one entity or group that feels responsible for that duty.”

Power utilities have a big interest in EVs. Despite continued economic growth, demand for electricity has stayed flat over the last decade, as businesses slash energy use and consumers switch to more power-thrifty appliances — LED light bulbs, flat-screen TVs, high-efficiency washers and dryers. EVs could drive up the demand for electricity, throwing a lifeline to power utilities. And yet, these companies largely aren’t building charging stations.

“For power utilities, the question is whether they see it as something that’s actually in their bailiwick or not,” Sifuentes said. Policymakers have not directed utilities to build out EV infrastructure, and with so few electric cars on the road, utilities are unlikely to take it upon themselves to start building charging stations.

         The Tesla Model 3

“The problem is that the charging infrastructure doesn’t have a viable business model yet,” said David Greene, a professor of civil and environmental engineering at the University of Tennessee. “Although, there are some companies who are working on it really hard.”

Private firms like EvBox and ChargePoint are looking to radically expand the number of available charging stations, but these plans depend on exponential growth in the sale of EVs. ChargePoint is looking to add 2.5 million charging stations to its global network of just 50,000, a goal it said is based on a “conservative view” of future EV sales. EvBox, meanwhile, is aiming for 1 million new charging stations. A spokesperson noted this target is “at least partly dependent on the number of electric vehicles on the road,” though he was similarly bullish on the growth of EVs. Analysts expect EV sales to increasedramatically in the coming years, though major roadblocks stand in the way of future adoption.

Even if EV sales take off and charging stations proliferate, barriers will remain. Making EVs more viable means installing not just more chargers, but more fast chargers that allow drivers to take long journeys. The difference between a fast charger and a slow charger is the difference between a family stopping for coffee while they refuel their car and a family stopping overnight.

A Chargepoint electric vehicle charging station.

 

“It’s 180 miles from Knoxville to Nashville. Supposedly there’s a [direct current] fast charger at a Cracker Barrel in Cookville, which is almost exactly halfway, but it almost never works,” Greene said. “The fact that the range is limited and the recharging time can be quite long if one does not have access to fast charging, that’s another problem.”

There is also the fact that the technology isn’t standardized. Different cars use different plugs. Ford and GM use one kind. Tesla uses another. Fast charging requires a different kind altogether. So, while charging stations dot the country, not every station meets every driver’s needs. Until manufacturers arrive at an industry standard — or policymakers mandate that standard —
“charging stations are going to need to have two or three different types of plugs, and people will need to be able to charge at different speeds because their car might not have a supercharger,” Sifuentes said.

Sifuentes believes that policymakers have a key role to play in building out charging stations. “They have to actually put in place laws and incentives that encourage the development of the necessary infrastructure, and I think that takes place in two ways,” he said. “One, encouraging utilities to do that. But also, I think we can’t ignore the role that public transit plays here.”

Different types of EV plugs.

 

New York City, he said, has pledged to switch to all-electric buses by 2040. “That means they’re going to have to put some serious charging infrastructure in place,” Sifuentes said. “If there’s a charging location that has to be put in because buses need to charge there but that’s available for private use as well, great.”

In addition to building public charging infrastructure, governments can also encourage the development of private charging infrastructure. Policymakers in Iowa and Austin, Texas, for example, are working to lower barriers to setting up charging stations, allowing private firms, as opposed to power utilities, to resell electricity. “I think the other role that policymakers have to play here is they have to actually put in place laws and incentives that encourage the development of the necessary infrastructure,” Sifuentes said.

In Norway, where EVs account for around a third of all new car sales, the government has gone a step further. The government is installing a fast charging station every 30 miles on main roads. EV drivers can get free charging at public stations in addition to free parking and free access to toll roads. Sifuentes said these kinds of policies are needed to spur the growth of EVs and support the installation of EV charging stations.

“We’re absolutely on the tipping point,” Sifeuntes said. “The more that we see EVs rolling out, the more and more it’s going to look like the right move to be putting this infrastructure in place.”

EV Charge 2 Fastned-solar-powered-EV-charger-NL

** Article from EcoWatch

Cost-effective method for hydrogen fuel production process discovered at U of A


NAno particles for hydrogen 190319121737_1_540x360

Researchers at the U of A have designed nanoparticles that act as catalysts, making the process of water electrolysis more efficient. Credit: Jingyi Chen, Lauren Greenlee and Ryan Manso

 

Nanoparticles composed of nickel and iron have been found to be more effective and efficient than other, more costly materials when used as catalysts in the production of hydrogen fuel through water electrolysis.

The discovery was made by University of Arkansas researchers Jingyi Chen, associate professor of physical chemistry, and Lauren Greenlee, assistant professor of chemical engineering, as well as colleagues from Brookhaven National Lab and Argonne National Lab.

The researchers demonstrated that using nanocatalysts composed of nickel and iron increases the efficiency of water electrolysis, the process of breaking water atoms apart to produce hydrogen and oxygen and combining them with electrons to create hydrogen gas.

Chen and her colleagues discovered that when nanoparticles composed of an iron and nickel shell around a nickel core are applied to the process, they interact with the hydrogen and oxygen atoms to weaken the bonds, increasing the efficiency of the reaction by allowing the generation of oxygen more easily. Nickel and iron are also less expensive than other catalysts, which are made from scarce materials.

This marks a step toward making water electrolysis a more practical and affordable method for producing hydrogen fuel. Current methods of water electrolysis are too energy-intensive to be effective.

Story Source:

Materials provided by University of ArkansasNote: Content may be edited for style and length.


Journal Reference:

  1. Ryan H. Manso, Prashant Acharya, Shiqing Deng, Cameron C. Crane, Benjamin Reinhart, Sungsik Lee, Xiao Tong, Dmytro Nykypanchuk, Jing Zhu, Yimei Zhu, Lauren F. Greenlee, Jingyi Chen. Controlling the 3-D morphology of Ni–Fe-based nanocatalysts for the oxygen evolution reactionNanoscale, 2019; DOI: 10.1039/C8NR10138H

MIT: New Optical Imaging System could be Deployed to find Tiny Tumors and Detect Cancer Earlier – “A Game Changing Method”


 

MIT-Deep-Tissue-Imaging-01_0

Near-infrared technology pinpoints fluorescent probes deep within living tissue; may be used to detect cancer earlier. MIT researchers have devised a way to simultaneously image in multiple wavelengths of near-infrared light, allowing them to determine the depth of particles emitting different wavelengths. Image courtesy of the researchers

Many types of cancer could be more easily treated if they were detected at an earlier stage. MIT researchers have now developed an imaging system, named “DOLPHIN,” which could enable them to find tiny tumors, as small as a couple of hundred cells, deep within the body. 

In a new study, the researchers used their imaging system, which relies on near-infrared light, to track a 0.1-millimeter fluorescent probe through the digestive tract of a living mouse. They also showed that they can detect a signal to a tissue depth of 8 centimeters, far deeper than any existing biomedical optical imaging technique.

The researchers hope to adapt their imaging technology for early diagnosis of ovarian and other cancers that are currently difficult to detect until late stages.

“We want to be able to find cancer much earlier,” says Angela Belcher, the James Mason Crafts Professor of Biological Engineering and Materials Science at MIT and a member of the Koch Institute for Integrative Cancer Research, and the newly-appointed head of MIT’s Department of Biological Engineering. “Our goal is to find tiny tumors, and do so in a noninvasive way.”

Belcher is the senior author of the study, which appears in the March 7 issue of Scientific Reports. Xiangnan Dang, a former MIT postdoc, and Neelkanth Bardhan, a Mazumdar-Shaw International Oncology Fellow, are the lead authors of the study. Other authors include research scientists Jifa Qi and Ngozi Eze, former postdoc Li Gu, postdoc Ching-Wei Lin, graduate student Swati Kataria, and Paula Hammond, the David H. Koch Professor of Engineering, head of MIT’s Department of Chemical Engineering, and a member of the Koch Institute.

Deeper imaging

Existing methods for imaging tumors all have limitations that prevent them from being useful for early cancer diagnosis. Most have a tradeoff between resolution and depth of imaging, and none of the optical imaging techniques can image deeper than about 3 centimeters into tissue. Commonly used scans such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI) can image through the whole body; however, they can’t reliably identify tumors until they reach about 1 centimeter in size.

Belcher’s lab set out to develop new optical methods for cancer imaging several years ago, when they joined the Koch Institute. They wanted to develop technology that could image very small groups of cells deep within tissue and do so without any kind of radioactive labeling.

Near-infrared light, which has wavelengths from 900 to 1700 nanometers, is well-suited to tissue imaging because light with longer wavelengths doesn’t scatter as much as when it strikes objects, which allows the light to penetrate deeper into the tissue. To take advantage of this, the researchers used an approach known as hyperspectral imaging, which enables simultaneous imaging in multiple wavelengths of light.

The researchers tested their system with a variety of near-infrared fluorescent light-emitting probes, mainly sodium yttrium fluoride nanoparticles that have rare earth elements such as erbium, holmium, or praseodymium added through a process called doping. Depending on the choice of the doping element, each of these particles emits near-infrared fluorescent light of different wavelengths.

Using algorithms that they developed, the researchers can analyze the data from the hyperspectral scan to identify the sources of fluorescent light of different wavelengths, which allows them to determine the location of a particular probe. By further analyzing light from narrower wavelength bands within the entire near-IR spectrum, the researchers can also determine the depth at which a probe is located. The researchers call their system “DOLPHIN”, which stands for “Detection of Optically Luminescent Probes using Hyperspectral and diffuse Imaging in Near-infrared.”

To demonstrate the potential usefulness of this system, the researchers tracked a 0.1-millimeter-sized cluster of fluorescent nanoparticles that was swallowed and then traveled through the digestive tract of a living mouse. These probes could be modified so that they target and fluorescently label specific cancer cells.

“In terms of practical applications, this technique would allow us to non-invasively track a 0.1-millimeter-sized fluorescently-labeled tumor, which is a cluster of about a few hundred cells. To our knowledge, no one has been able to do this previously using optical imaging techniques,” Bardhan says.

Earlier detection

The researchers also demonstrated that they could inject fluorescent particles into the body of a mouse or a rat and then image through the entire animal, which requires imaging to a depth of about 4 centimeters, to determine where the particles ended up. And in tests with human tissue-mimics and animal tissue, they were able to locate the probes to a depth of up to 8 centimeters, depending on the type of tissue.

Guosong Hong, an assistant professor of materials science and engineering at Stanford University, described the new method as “game-changing.”

“This is really amazing work,” says Hong, who was not involved in the research. “For the first time, fluorescent imaging has approached the penetration depth of CT and MRI, while preserving its naturally high resolution, making it suitable to scan the entire human body.”

Early Detect cancer-cells-600Read More About the Importance of Early Detection

This kind of system could be used with any fluorescent probe that emits light in the near-infrared spectrum, including some that are already FDA-approved, the researchers say. The researchers are also working on adapting the imaging system so that it could reveal intrinsic differences in tissue contrast, including signatures of tumor cells, without any kind of fluorescent label.

In ongoing work, they are using a related version of this imaging system to try to detect ovarian tumors at an early stage. Ovarian cancer is usually diagnosed very late because there is no easy way to detect it when the tumors are still small.

“Ovarian cancer is a terrible disease, and it gets diagnosed so late because the symptoms are so nondescript,” Belcher says. “We want a way to follow recurrence of the tumors, and eventually a way to find and follow early tumors when they first go down the path to cancer or metastasis. This is one of the first steps along the way in terms of developing this technology.”

The researchers have also begun working on adapting this type of imaging to detect other types of cancer such as pancreatic cancer, brain cancer, and melanoma.

The research was funded by the Koch Institute Frontier Research Program, the Marble Center for Cancer Nanomedicine, the Koch Institute Support (core) Grant from the National Cancer Institute, the NCI Center for Center for Cancer Nanotechnology Excellence, and the Bridge Project.

VW says it accelerates plan for 22 million electric vehicles in 10 yrs as part of decarbonization plan


Volkswagen_I.D._concept_family-Large-7737-e1531939866114

Volkswagen announced today its intention to accelerate its electrification effort as part of its decarbonization plan by adding 20 more “electric models” to its planned lineup in order to produce 22 million electric vehicles in the next 10 years.Those 22 million vehicles will now consist of 70 different models released across Volkswagen’s multiple brands.

Dr. Herbert Diess, CEO of Volkswagen AG, said at the company’s annual meeting:

“Volkswagen is taking on responsibility with regard to the key trends of the future – particularly in connection with climate protection. The targets of the Paris Agreement are our yardstick. We will be systematically aligning production and other stages in the value chain to CO2 neutrality in the coming years. That is how we will be making our contribution towards limiting global warming. Volkswagen is seeking to provide individual mobility for millions of people for years to come – individual mobility that is safer, cleaner and fully connected. In order to shoulder the investments needed for the electric offensive we must make further improvements in efficiency and performance in all areas.”

The German automaker also reiterated its three-part plan to decarbonize its operation by “first, effective and sustainable CO2 reduction. Second, switch to renewable energy sources for power supply. Third, compensate for remaining emissions that cannot be avoided.”

Electrek’s Take

I know VW gets a lot of flak for always talking about its ambitious electric vehicle plans instead of delivering them, but they are coming people.

It’s easy to say that, but they are coming. It’s just that these big legacy automakers move slow.

What is important is that in the case of VW, we have seen them make a significant investment to convert gasoline and diesel vehicle production capacity to electric vehicle production capacity.

Now the vehicles are slowly starting to come this year.

In the new press release, they listed the current known lineup to make sure everyone remembers:

  • Audi e-tron
  • Porsche Taycan
  • Volkswagen ID
  • ID. CROZZ
  • el-born
  •  ŠKODA Vision E
  • ID. BUZZ
  • ID. VIZZION

These vehicles are all at various stages of production and development, but they have all been greenlighted for volume production.

That said, it won’t be an easy transition for Volkswagen. They have already run into a lot of troubles delivering the e-tron.

It will be interesting to see how they handle those next few years.

** Article Re-Posted from Electrek

A new strategy of fabricating p-n junction in single crystalline Si nanowires, twisting


anewstrategy
Illustration of the relative formation energy as function of twist rate γ of doped Si nanowire for Sb and B dopants at different atomic sites. The strain-free and twisted Si nanowires are shown at the axial view. Credit: ©Science China Press

Can single crystalline materials be used for low dimensional p-n junction design? This is an open and long-standing problem. Microscopic simulations based on the generalized Bloch theorem show that in single crystalline Si nanowires, an axial twist can lead to the separation of p-type and n-type dopants along the nanowire radial dimension, and thus realizes the p-n junction. A bond orbital analysis reveals that this is due to the twist-induced inhomogeneous shear strain in the nanowire.

If a semiconductor crystal is doped with  dopants in one region and with  dopants in another region, a p-n junction configuration is formed. P-n junctions are fundamental building units of light emitting diodes, solar cells and other semiconductor transistors. P-n junctions in nano-structures are also expected to be the fundamental units of next generation nano-devices.

However, due to the strong attraction between them, n-type dopants and p-type dopants tend to form neutral pairs. As a result, the p-n junction fails. To prevent such attraction between n-type dopants and p-type dopants, heterostructures are introduced, where one  is doped with n-type dopants while the other is doped with p-type dopants, and the interface between two different semiconductor materials acts as an  between n-type dopants and p-type dopants.

Indeed, the usage of heterostructures stands for a paradigm for the material design of p-n junction. Recently, similar  configurations are also possible for nanowire heterostructures such as co-axial core-shell nanowires. However, there are several limitations in nanowire heterostructures. For example, the synthesis of core-shell nanowires usually involves a two-step process, which costs extra expense. Often the shell of the obtained nanowire heterostructure is polycrystalline. Such imperfection goes ill with the transports of carriers. Furthermore, the interface between the core and shell also introduces detrimental deep centers that largely hinder the device efficiency.

Can we make p-n junctions with single crystalline nanowires? Frankly, the answer will be “No” if one thinks the problem intuitively. Indeed, similar to the bulk, p-type dopants and n-type dopants in a codoped single crystalline nanowire also feel strong Coulomb attraction. Without an interface, how can we overcome such attraction? It requires an effective modulation/control of the spatial occupation sites, i.e., spatial distribution, of dopants. In fact, this is one of the long-standing and fundamental issues regarding doping in semiconductor.

From the point of view of materials engineering, this can be attributed to the failure of conventional approaches such as hydrostatic, biaxial and uniaxial stresses on the modulation of the spatial distribution of dopants. However, since all these mentioned distortions are uniform, can we employ some inhomogeneous ones, such as twisting? In fact, twisting of structures represents a focus of recent condensed matter physics research in low dimensions.

In a new paper published in National Science Review, a team of scientists from Beijing Normal University, the Chinese University of Hong Kong, and Beijing Computational Science Research Center present their theoretical advances of codoped Si nanowire under twisting. They employ both microscopic simulations based on the generalized Bloch theorem and analytical modeling based on the bond orbital theory to conduct the study and deliver the physics behind.

Interestingly, twisting has substantial impact on distribution of dopants in . From the displayed figure, in a twisted Si nanowire, a  of larger atomic size (Such as Sb) has a lower formation energy if it occupies an atomic site closer to nanowire surface; On the opposite, a dopant of smaller atomic size (Such as B) has a lower formation energy if it occupies an atomicsites around the nanowire core. According to their calculations, it is possible to separate n-type and p-type dopants in the codoped nanowire with proper choices of codoping pairs, e.g., B and Sb. A bond orbital analysis reveals that it is the twist-induced inhomogeneous shear strain along nanowire radial dimension that drives the effective modulation. These findings are fully supported by density-functional tight-binding based generalized Bloch theorem simulations.

This new strategy largely simplifies the manufacturing process and lowers the manufacturing costs. If the twisting is applied when the device is in working mode, the recombination of different types of dopants is largely suppressed. Even if the twisting is removed when the device is in working mode, due to the limited diffusion, the recombination is still difficult.

 Explore further: Researchers decipher electrical conductivity in doped organic semiconductors

More information: Dong-Bo Zhang et al, Twist-Driven Separation of p-type and n-type Dopants in Single Crystalline Nanowires, National Science Review (2019). DOI: 10.1093/nsr/nwz014

 

UCLA School of Dentistry: New membrane class shown to regenerate tissue and bone, viable solution for periodontitis


newmembranecA multifunctional periodontal membrane is surgically inserted into the pocket between affected gums and tooth. This new membrane has shown to protect the site from further infection as well as to help regrow bone. Credit: UCLA School of Dentistry

Periodontitis affects nearly half of Americans ages 30 and older, and in its advanced stages, it could lead to early tooth loss or worse. Recent studies have shown that periodontitis could also increase risk of heart disease and Alzheimer’s disease.

A team of UCLA researchers has developed methods that may lead to more effective and reliable therapy for periodontal disease—ones that promote gum tissue and bone regeneration with biological and mechanical features that can be adjusted based on treatment needs. The study is published online in ACS Nano.

Periodontitis is a chronic, destructive disease that inflames the gums surrounding the tooth and eventually degrades the structure holding the tooth in place, forming infected pockets leading to bone and tooth loss. Current treatments include infection-fighting methods; application of molecules that promote tissue growth, also known as growth factors; and guided tissue regeneration, which is considered the optimal standard of care for the treatment of periodontitis.

Guided tissue regeneration, in the case of periodontitis, involves the use of a membrane or thin film that is surgically placed between the inflamed gum and the tooth. Membranes, which come in non-biodegradable and biodegradable forms, are meant to act not only as barriers between the infection and the gums, but also as a delivery system for drugs, antibiotics and growth factors to the gum tissue.

Unfortunately, results from guided tissue regeneration are inconsistent. Current membranes lack the ability to regenerate gum tissue directly and aren’t able to maintain their structure and stability when placed in the mouth. The membrane also can’t support prolonged drug delivery, which is necessary to help heal infected gum tissue. For non-biodegradable membranes, multiple surgeries are needed to remove the membrane after any drugs have been released—compromising the healing process.

“Given the current disadvantages with guided tissue regeneration, we saw the need to develop a new class of membranes, which have tissue and bone regeneration properties along with a flexible coating that can adhere to a range of biological surfaces,” said Dr. Alireza Moshaverinia, lead author of the study and assistant professor of prosthodontics at the UCLA School of Dentistry. “We’ve also figured out a way to prolong the drug delivery timeline, which is key for effective wound healing.”

The team started with an FDA-approved polymer—a large-scale synthetic molecule commonly used in biomedical applications. Because the polymer’s surface isn’t suitable for cell adhesion in periodontal treatment, the researchers introduced a polydopamine coating—a polymer that has excellent adhesive properties and can attach to surfaces in wet conditions. The other benefit of using such a coating is that it speeds up bone regeneration by promoting mineralization of hydroxyapatite, which is the mineral that makes up tooth enamel and bone.

After identifying an optimal combination for their new membrane, the researchers used electrospinning to bond the polymer with the polydopamine coating. Electrospinning is a production method that simultaneously spins two substances at a rapid speed with positive and negative charges, and fuses them together to create one substance. To improve their new membrane’s surface and structural characteristics, the researchers used metal mesh templates in conjunction with the electrospinning to create different patterns, or micro-patterning, similar to the surface of gauze or a waffle.

“By creating a micro pattern on the surface of the membrane, we are now able to localize cell adhesion and to manipulate the membrane’s structure,” said co-lead author Paul Weiss, UC presidential chair and distinguished professor of chemistry and biochemistry, bioengineering, and materials science and engineering at UCLA. “We were able to mimic the complex structure of periodontal tissue and, when placed, our membrane complements the correct biological function on each side.”

To test the safety and efficiency of their new membrane, the researchers injected rat models with gingival-derived human stem cells and human periodontal ligament stem cells. After eight weeks of evaluating the degradation of the membranes and the tissue’s response, they observed that the patterned, polydopamine-coated polymer membrane had higher levels of bone gain when compared to models with no membrane or a membrane with no coating.

In order to suit a wide range of medical and dental applications, the researchers also figured out a way to adjust the speed at which their membranes degraded when inserted in their models. They did this by adding and subtracting different oxidative agents or using lighter polymer bases before going through the electrospinning process. The ability to turn the degradation rates up or down helped the researchers control the timing of the delivery of drugs to the desired areas.

“We’ve determined that our membranes were able to slow down periodontal infection, promote bone and tissue regeneration, and stay in place long enough to prolong the delivery of useful drugs,” Moshaverinia said. “We see this application expanding beyond periodontitis treatment to other areas needing expedited wound healing and prolonged drug delivery therapeutics.”

The researchers’ next steps are to evaluate whether their membranes can deliver cells with growth factors in the presence or absence of stem cells.

 Explore further: Microscopic membrane could fight gum disease

More information: Mohammad Mahdi Hasani-Sadrabadi et al. Hierarchically Patterned Polydopamine-Containing Membranes for Periodontal Tissue Engineering, ACS Nano (2019). DOI: 10.1021/acsnano.8b09623

 

Visualizing the World’s EV Markets – Who is the World’s Undisputed Leader in EV Adoption?


It took five years to sell the first million electric cars. In 2018, it took only six months.

The Tesla Model 3 also passed a significant milestone in 2018, becoming the first electric vehicle (EV) to crack the 100,000 sales mark in a single year. The Nissan LEAF and BAIC EC-Series are both likely to surpass the 100,000 this year as well.

Although the electric vehicle market didn’t grow as fast as some experts initially projected, it appears that EV sales are finally hitting their stride around the world. Below are the countries where electric vehicles are a biggest part of the sales mix.

The EV Capital of the World

Norway, after amassing a fortune through oil and gas extraction, made the conscious decision to create incentives for its citizens to purchase electric vehicles. As a result, the country is the undisputed leader in EV adoption.

In 2018, a one-third of all passenger vehicles were fully electric, and that percentage is only expected to increase in the near future. The Norwegian government has even set the ambitious target of requiring all new cars to be zero-emission by 2025.

That enthusiasm for EVs is spilling over to other countries in the region, which are also seeing a high percentage of EV sales. However, the five countries in which EVs are the most popular – Norway, Iceland, Sweden, Netherlands, and Finland – only account for 0.5% of the world’s population. For EV adoption to make any real impact on global emissions, drivers in high-growth/high–population countries will need to opt for electric powered vehicles. (Of course power grids will need to get greener as well, but that’s another topic.)

China’s Supercharged Impact

One large economy that is embracing plug-in vehicles is China. 

The country leads the world in electric vehicle sales, with over a million new vehicles hitting the roads in 2018. Last year, more EVs were sold in Shenzhen and Shanghai than any country in the world, with the exception of the United States.

China also leads the world in another important metric – charging stations. Not only does China have the highest volume of chargers, many of them allow drivers to charge up faster.

Electric vehicle charging stations

Accelerating from the Slow Lane

In the United States, electric vehicle sales are rising, but they still tend to be highly concentrated in specific areas. In around half of states, EVs account for fewer than 1% of vehicle sales. On the other hand, California is approaching the 10% mark, a significant milestone for the most populous state.

Nationally, EV sales increasedthroughout 2018, with December registering nearly double the sales volume of the same month in 2017. Part of this surge in sales is driven by the Tesla’s Model 3, which led the market in the last quarter of 2018.

U.S. Electric vehicle sales

North of the border, in Canada, the situation is similar. EV sales are increasing, but not fast enough to meet targets set by the government. Canada aimed to have half a million EVs on the road by 2018, but missed that target by around 400,000 vehicles.

The big question now is whether the recent surge in sales is a temporary trend driven by government subsidies and showmanship of Elon Musk, or whether EVs are now becoming a mainstream option for drivers around the world.

Scientists ‘Reverse Time’ with a Quantum Computer


“Now the thing about time is that time isn’t really real.

It’s just your point of view, how does it feel to you?

Einstein said we could never understand it all … “

James Taylor ~ “The Secret of Life”

Researchers from the Moscow Institute of Physics and Technology teamed up with colleagues from the U.S. and Switzerland and returned the state of a quantum computer a fraction of a second into the past.

They also calculated the probability that an electron in empty interstellar space will spontaneously travel back into its recent past. The study is published in Scientific Reports.

“This is one in a series of papers on the possibility of violating the . That law is closely related to the notion of the arrow of time that posits the one-way direction of time from the past to the future,” said the study’s lead author Gordey Lesovik, who heads the Laboratory of the Physics of Quantum Information Technology at MIPT.

“We began by describing a so-called local perpetual motion machine of the second kind. Then, in December, we published a paper that discusses the violation of the second law via a device called a Maxwell’s demon,” Lesovik said. “The most recent paper approaches the same problem from a third angle: We have artificially created a state that evolves in a direction opposite to that of the thermodynamic arrow of time.”

What makes the future different from the past

Most laws of physics make no distinction between the future and the past. For example, let an equation describe the collision and rebound of two identical billiard balls. If a close-up of that event is recorded with a camera and played in reverse, it can still be represented by the same equation. Moreover, it is not possible to distinguish from the recording if it has been doctored. Both versions look plausible. It would appear that the billiard balls defy the intuitive sense of time.

However, imagine recording a cue ball breaking the pyramid, the billiard balls scattering in all directions. In that case, it is easy to distinguish the real-life scenario from reverse playback. What makes the latter look so absurd is our intuitive understanding of the second law of thermodynamics—an isolated system either remains static or evolves toward a state of chaos rather than order.

Most other laws of physics do not prevent rolling billiard balls from assembling into a pyramid, infused tea from flowing back into the tea bag, or a volcano from “erupting” in reverse.

But these phenomena are not observed, because they would require an isolated system to assume a more ordered state without any outside intervention, which runs contrary to the second law. The nature of that law has not been explained in full detail, but researchers have made great headway in understanding the basic principles behind it.

Read More: “Quantum Time Travel”

Spontaneous time reversal

Quantum physicists from MIPT decided to check if time could spontaneously reverse itself at least for an individual particle and for a tiny fraction of a second. That is, instead of colliding billiard balls, they examined a solitary electron in empty interstellar space.

“Suppose the electron is localized when we begin observing it. This means that we’re pretty sure about its position in space. The laws of quantum mechanics prevent us from knowing it with absolute precision, but we can outline a small region where the electron is localized,” says study co-author Andrey Lebedev from MIPT and ETH Zurich.

The physicist explains that the evolution of the electron state is governed by Schrödinger’s equation. Although it makes no distinction between the future and the past, the region of space containing the electron will spread out very quickly. That is, the system tends to become more chaotic. The uncertainty of the electron’s position is growing. This is analogous to the increasing disorder in a large-scale system—such as a billiard table—due to the second law of thermodynamics.

The four stages of the actual experiment on a quantum computer mirror the stages of the thought experiment involving an electron in space and the imaginary analogy with billiard balls. Each of the three systems initially evolves from order toward chaos, but then a perfectly timed external disturbance reverses this process. Credit: @tsarcyanide/MIPT

“However, Schrödinger’s equation is reversible,” adds Valerii Vinokur, a co-author of the paper, from the Argonne National Laboratory, U.S.

“Mathematically, it means that under a certain transformation called complex conjugation, the equation will describe a ‘smeared’ electron localizing back into a small region of space over the same time period.”

Although this phenomenon is not observed in nature, it could theoretically happen due to a random fluctuation in the cosmic microwave background permeating the universe.

The team set out to calculate the probability to observe an electron “smeared out” over a fraction of a second spontaneously localizing into its recent past. It turned out that even across the entire lifetime of the universe—13.7 billion years—observing 10 billion freshly localized electrons every second, the reverse evolution of the particle’s state would only happen once. And even then, the electron would travel no more than a mere one ten-billionth of a second into the past.

Large-scale phenomena involving billiard balls and volcanoes obviously unfold on much greater timescales and feature an astounding number of  and other particles. This explains why we do not observe old people growing younger or an ink blot separating from the paper.

Reversing time on demand

The researchers then attempted to reverse time in a four-stage experiment. Instead of an electron, they observed the state of a quantum computer made of two and later three basic elements called superconducting qubits.

  • Stage 1: Order. Each qubit is initialized in the ground state, denoted as zero. This highly ordered configuration corresponds to an electron localized in a small region, or a rack of billiard balls before the break.
  • Stage 2: Degradation. The order is lost. Just like the electron is smeared out over an increasingly large region of space, or the rack is broken on the pool table, the state of the qubits becomes an ever more complex changing pattern of zeros and ones. This is achieved by briefly launching the evolution program on the quantum computer. Actually, a similar degradation would occur by itself due to interactions with the environment. However, the controlled program of autonomous evolution will enable the last stage of the experiment.
  • Stage 3: Time reversal. A special program modifies the state of the quantum computer in such a way that it would then evolve “backwards,” from chaos toward order. This operation is akin to the random microwave background fluctuation in the case of the electron, but this time, it is deliberately induced. An obviously far-fetched analogy for the billiards example would be someone giving the table a perfectly calculated kick.
  • Stage 4: Regeneration. The evolution program from the second stage is launched again. Provided that the “kick” has been delivered successfully, the program does not result in more chaos but rather rewinds the state of the qubits back into the past, the way a smeared electron would be localized or the billiard balls would retrace their trajectories in reverse playback, eventually forming a triangle.

The researchers found that in 85 percent of the cases, the two-qubit quantum computer returned back into the initial state. When three qubits were involved, more errors happened, resulting in a roughly 50 percent success rate. According to the authors, these errors are due to imperfections in the actual quantum computer. As more sophisticated devices are designed, the error rate is expected to drop.

Interestingly, the time reversal algorithm itself could prove useful for making quantum computers more precise. “Our algorithm could be updated and used to test programs written for computers and eliminate noise and errors,” Lebedev explained.

More information: Scientific Reports(2019). DOI: 10.1038/s41598-019-40765-6

Provided by Moscow Institute of Physics and Technology

Explore further: Quantum Maxwell’s demon ‘teleports’ entropy out of a qubit

Graphene quantum dots for single electron transistors ~ Application for Future Electronics


The schematic structure of the devices

Scientists from Manchester University, the Ulsan National Institute of Science & Technology and the Korea Institute of Science and Technology have developed a novel technology, which combines the fabrication procedures of planar and vertical heterostructures in order to assemble graphene-based single-electron transistors.

In the study, it was demonstrated that high-quality graphene quantum dots (GQDs), regardless of whether they were ordered or randomly distributed, could be successfully synthesized in a matrix of monolayer hexagonal boron nitride (hBN).

Here, the growth of GQDs within the layer of hBN was shown to be catalytically supported by the platinum (Pt) nanoparticles distributed in-between the hBN and supporting oxidised silicon (SiO2) wafer, when the whole structure was treated by the heat in the methane gas (CH4). It was also shown, that due to the same lattice structure (hexagonal) and small lattice mismatch (~1.5%) of graphene and hBN, graphene islands grow in the hBN with passivated edge states, thereby giving rise to the formation of defect-less quantum dots embedded in the hBN monolayer.

Such planar heterostructures incorporated by means of standard dry-transfer as mid-layers into the regular structure of vertical tunnelling transistors (Si/SiO2/hBN/Gr/hBN/GQDs/hBN/Gr/hBN; here Gr refers to monolayer graphene and GQDs refers to the layer of hBN with the embedded graphene quantum dots) were studied through tunnel spectroscopy at low temperatures (3He, 250mK).

The study demonstrated where the manifestation of well-established phenomena of the Coulomb blockade for each graphene quantum dot as a separate single electron transmission channel occurs.

‘Although the outstanding quality of our single electron transistors could be used for the development of future electronics, “This work is most valuable from a technological standpoint as it suggests a new platform for the investigation of physical properties of various materials through a combination of planar and van der Waals heterostructures.” as explained study co-author Davit Ghazaryan, Associate Professor at the HSE Faculty of Physics, and Research Fellow at the Institute of Solid State Physics (RAS)