Update: All-Electric Car Range, Price & More Compared For U.S. – July 2019


The BEV offer in the U.S. is getting more attractive on both ends – affordable and high-end. 

The third quarter of this year brings us several changes in pricing and availability of all-electric cars in the U.S.– those changes are mostly related to Tesla models.

First of all, from July on, Tesla buyers can count on only $1,875 of federal tax credit (instead of $3,750). Secondly, Tesla lowered prices of 3/S/X and dropped some versions entirely. Other than that, we didn’t note any important changes, but as always in the car business – the real prices can be much lower than MSRP (like the Chevrolet Bolt EV, for example) or much higher than MSRP (when a particular model is production constrained).

Below we attached a comparison in the form of a table as well as charts, sorted by range and by price. Each position is a separate model (or version if there are differences in range or powertrain).

All-Electric Cars Compared By Range, U.S. – July 22, 2019

The range of BEVs varies from less than 60 miles to 370 miles (595 km), according to the EPA. Six Tesla versions are above 300 miles, in total 16 BEVs are above 200 miles.

All-Electric Cars Compared By Price, U.S. – July 22, 2019

Taking into consideration MSRP and deducting the federal tax credit, the base 200+ mile range electric cars start at around $30,000.

As many Chevrolet dealers often lower the Bolt EV price by several thousand, you could get a 200+ mile BEV for less than $30,000.

** Some models estimated.

Article re-posted from InsideEvs.

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Successful Entrepreneurs and Chinese Bamboo Trees have a Lot in Common


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Most entrepreneurs will tell you that it’s perfectly reasonable to quit after five years of not seeing results. In fact, I don’t think many business owners would last five years. I’ll be the first to admit that I would just give up after no results around year three or four.

 

Now, here’s an interesting story a coach of mine told me a while ago that has a great lesson for entrepreneurs. It’s the story of the Chinese Bamboo Tree.

To grow the Chinese Bamboo Tree, you’d water it, make sure that it gets enough sunshine — all the usual stuff. But even if you do everything right, you won’t see any visible signs of growth in the first year. Nor the second, third, or fourth year.

 

But in the fifth year, something magical happens! Your plant, which has been dormant all this time, suddenly shoots up by 80 feet in just six weeks, and it becomes virtually unrecognizable over that short span of time.

The Chinese Bamboo Tree story is pretty amazing in its own right, and it gets even cooler when you realize that this mirrors the situation that entrepreneurs face in real life. Here are three takeaways from the story that you can apply to your business to help it grow:

1. Work on your foundation.

If you’re working on a new business, the first thing that you should do is work on your foundation. Create processes and systems to streamline your workflow. Hire the right people. Train them, and teach them to solve problems.

Once you’ve put together a strong foundation for your company, it’ll start growing really fast — just like the Chinese Bamboo Tree. Just remember to be patient while you build on that foundation, and don’t fall into the trap of cutting corners.

As entrepreneurs, we all talk about scaling our companies and gaining traction, but keep in mind that this doesn’t happen overnight. Even if you pump in $50,000 into Facebook ads or Google ads, and get a ton of orders, it’ll be hard for you to fulfill those orders effectively and keep your customers happy if you don’t have a solid foundation to start off with.

2. Reinvest your money in your business.

Once you start making money, reinvest the money into your business so that you can keep growing and building upon that foundation.

 

 

More specifically, spend on customer service so that you can provide a better experience, spend on new technology so you can automate certain processes and boost productivity, and spend on coaching so you can identify your weaknesses and improve upon them.

 

Bambbo tree 1 20080318-BAMBOO2

Read More: 6 Success Lessons You Should Learn from a Bamboo Tree

Personally, I hired a coach to help me take my business to the next level, and after implementing his suggestions (creating operational manuals, organizational charts, etc), I’ve definitely noticed an increase in my team’s effectiveness.

Entrepreneur 1 download3. Stop chasing shiny objects.

Finally, stop getting distracted by every new tactic, strategy, or marketing channel that you hear about. At the end of the day, you don’t want to spread yourself too thin — this will hurt your focus, and make it hard for you to achieve your business goals.

 

Think about it: say you’re taking care of your Chinese Bamboo Tree, and after seeing that it’s not growing, you try giving it a different brand of fertilizer every week. I’m no expert on gardening, but even I can tell you that you’ll kill the plant by the end of the month.

 

Posted from Inc. Business Forum: T. Mello

Graphene Container System for Manufacturing


A graphene container system for manufacturing has been developed by GrapheneCA. The 40-foot containers are designed specifically for industrial producers and high-tech applications of graphene.

“It has developed a novel Mobile Graphene Container System (MGCS), the world’s first scalable, modular graphene production system, to help companies manufacture graphene in-house.
 
The New York-based company, which develops graphene-based technology for industries, said MGCS is available in 40-foot containers that are designed specifically for industrial producers and high-tech applications. The company said that with MGCS’ high quality, “ecologically clean graphene can be produced in-house” anywhere in the world.
 
“Think of Mobile Graphene Container System as your own graphene production line,” said David Robles, head of business development at GrapheneCA. “Producers will be able to secure a constant graphene supply and have greater control over their production volume and price.”
 
Robles said the process eliminates the reliance on “third-party suppliers and complicated logistics.”The industrial containers produce a high volume of industrial graphene in quantities of 4 tons of powder or more than 12 tons of graphene paste, said the company.
 
For high-tech applications, MGCS is able to produce pure graphene and graphene oxides derivatives, a much finer quality of product. The manufactured products have additional drying and quality-control features that reduce the need for graphene experts.
 
The company said that the next generation method simplifies graphene production and addresses problems that crop up during product shipments.
 
Graphene shipping is filled with complications due to the material being a highly voluminous compound, greatly limiting the amount of product that can be stored in a shipping container. MGCS allows for a clever work-around whereby ecologically clean graphene can be produced in-house by a company eliminating high shipping costs. Production only needs a water source and electric, diesel or bio-diesel power.”

 
Read full article GrapheneCA creates mobile graphene container system for in-house graphene manufacturing

The Nano–Bio Interactions of Nanomedicines: ENMs – Understanding the Biochemical Driving Forces and Redox Reactions


Engineered nanomaterials (ENMs) have been developed for imaging, drug delivery, diagnosis, and clinical therapeutic purposes because of their outstanding physicochemical characteristics.

However, the function and ultimate efficiency of nanomedicines remain unsatisfactory for clinical application, mainly because of our insufficient understanding of nanomaterial/nanomedicine–biology (nano–bio) interactions.

The nonequilibrated, complex, and heterogeneous nature of the biological milieu inevitably influences the dynamic bioidentity of nanoformulations at each site (i.e., the interfaces at different biological fluids (biofluids), environments, or biological structures) of nano–bio interactions.

The continuous interplay between a nanomedicine and the biological molecules and structures in the biological environments can, for example, affect cellular uptake or completely alter the designed function of the nanomedicine.

Accordingly, the weak and strong driving forces at the nano–bio interface may elicit structural reconformation, decrease bioactivity, and induce dysfunction of the nanomaterial and/or redox reactions with biological molecules, all of which may elicit unintended and unexpected biological outcomes.

In contrast, these driving forces also can be manipulated to mitigate the toxicity of ENMs or improve the targeting abilities of ENMs.

Therefore, a comprehensive understanding of the underlying mechanisms of nano–bio interactions is paramount for the intelligent design of safe and effective nanomedicines.

In this Account, we summarize our recent progress in probing the nano–bio interaction of nanomedicines, focusing on the driving force and redox reaction at the nano–bio interface, which have been recognized as the main factors that regulate the functions and toxicities of nanomedicines.

First, we provide insight into the driving force that shapes the boundary of different nano–bio interfaces (including proteins, cell membranes, and biofluids), for instance, hydrophobic, electrostatic, hydrogen bond, molecular recognition, metal-coordinate, and stereoselective interactions that influence the different nano–bio interactions at each contact site in the biological environment.

The physicochemical properties of both the nanoparticle and the biomolecule are varied, causing structure recombination, dysfunction, and bioactivity loss of proteins; correspondingly, the surface properties, biological functions, intracellular uptake pathways, and fate of ENMs are also influenced.

Second, with the help of these driving forces, four kinds of redox interactions with reactive oxygen species (ROS), antioxidant, sorbate, and the prosthetic group of oxidoreductases are utilized to regulate the intracellular redox equilibrium and construct synergetic nanomedicines for combating bacteria and cancers. Three kinds of electron-transfer mechanisms are involved in designing nanomedicines, including direct electron injection, sorbate-mediated, and irradiation-induced processes.

Finally, we discuss the factors that influence the nano–bio interactions and propose corresponding strategies to manipulate the nano–bio interactions for advancing nanomedicine design. We expect our efforts in understanding the nano–bio interaction and the future development of this field will bring nanomedicine to human use more quickly.

New stable, transparent, and flexible electronic device that emulates essential synaptic behaviors, with potential for #AI in organic environments.


Structure and materials of the transparent and flexible synapses. a) Illustration of the identical bio-synapse and artificial synapse structures.

Waterproof artificial synapses for pattern recognition in organic environments

The two electrodes and the functional layer correspond to pre-synapse, post-synapse, and synaptic cleft, respectively. b) Schematic of the ITO/PEDOT:PSS/ITO flexible and transparent artificial synaptic device. c) Top and d) cross- sectional SEM images of the PEDOT:PSS film on the Si substrate. The film thickness was 42.18 nm. e) Schematic structure and f) Raman spectra of PEDOT:PSS. g) Transmittance spectrum of the PET/ITO, PET/ITO/PEDOT:PSS, and PET/ITO/PEDOT:PSS/ITO structures. h) AFM image (2×2 μm2) of the PEDOT:PSS film on the PET/ITO substrate. Root-mean-square average roughness (Rq) was 1.99 nm. Credit: Wang et al.

Most artificial intelligence (AI) systems try to replicate biological mechanisms and behaviors observed in nature. One key example of this is electronic synapses (e-synapses), which try to reproduce junctions between nerve cells that enable the transmission of electrical or chemical signals to target cells in the human body, known as synapses.

Over the past few years, researchers have simulated versatile functions using single physical devices. These devices could soon enable advanced learning and memory capabilities in machines, emulating functions of the human brain. 

Recent studies have proposed flexible, transparent and even bio-compatible electronic devices for pattern recognition, which could pave the way toward a new generation of wearable and  synaptic systems. These “invisible” e-synapses, however, come with a notable disadvantage: they easily dissolve in water or in organic solutions, which is far from ideal for wearable applications. 

To overcome this limitation, researchers at Fudan University in Shangai have set out to develop a new stable, flexible and waterproof synapse suitable for applications in organic environments. Their study, outlined in a paper published in the Royal Society of Chemistry’s Nanoscale Horizons journal, presents a new fully transparent electronic  that emulates essential synaptic behaviors, such as paired-pulse facilitation (PPF), long-term potentiation/depression (LTP/LTD) and learning-forgetting-relearning processes. 

“In the present work, a stable waterproof artificial synapse based on a fully transparent electronic device, suitable for wearable applications in an organic environment, is for the first time demonstrated,” the researchers wrote in their paper.

The flexible, fully transparent and waterproof device developed by the researchers has so far achieved remarkable results, with an optical transmittance of ~87.5 percent in the visible light range. It was also able to reliable replicate LTP/LTD processes under bended states. LTP/LTD are two processes affecting , which respectively entail an enhancement and decrease in synaptic strength. 

The researchers tested their synapses by immersing them in water and in five common organic solvents for over 12 hours. They found that they functioned with 6000 spikes without noticeable degradation. The researchers also used their e-synapses to develop a device-to-system-level simulation framework, which achieved a handwritten digit recognition accuracy of 92.4 percent. 

“The device demonstrated an excellent transparency of 87.5 percent at 550nm wavelength and flexibility at a radius of 5mm,” the researchers wrote in their paper. “Typical synaptic plasticity characteristics, including EPSC/IPSC, PPF and learning-forgetting-relearning processes, were emulated. Furthermore, the e-synapse exhibited reliable LTP/LTD behaviors at flat and bended states, even after being immersed in water and organic solvents for over 12 hours.” 

The device proposed by this team of researchers is the first “invisible” and waterproof e-synapse that can reliably operate in organic environments without any damage or deterioration. In the future, it could aid the development of new reliable brain-inspired neuromorphic systems, including  and implantable devices.

More information: Tian-Yu Wang et al. Fully transparent, flexible and waterproof synapses with pattern recognition in organic environments, Nanoscale Horizons (2019). DOI: 10.1039/C9NH00341J

© 2019 Science X Network

Researchers at Oregon State University reach Milestone in use of Nanoparticles to kill Cancer with Heat


Abstract:
Researchers at Oregon State University have developed an improved technique for using magnetic nanoclusters to kill hard-to-reach tumors.

 

Magnetic nanoparticles – tiny pieces of matter as small as one-billionth of a meter – have shown anti-cancer promise for tumors easily accessible by syringe, allowing the particles to be injected directly into the cancerous growth.

Once injected into the tumor, the nanoparticles are exposed to an alternating magnetic field, or AMF. This field causes the nanoparticles to reach temperatures in excess of 100 degrees Fahrenheit, which causes the cancer cells to die.

But for some cancer types such as prostate cancer, or the ovarian cancer used in the Oregon State study, direct injection is difficult. In those types of cases, a “systemic” delivery method – intravenous injection, or injection into the abdominal cavity – would be easier and more effective.

The challenge for researchers has been finding the right kind of nanoparticles – ones that, when administered systemically in clinically appropriate doses, accumulate in the tumor well enough to allow the AMF to heat cancer cells to death.

Olena Taratula and Oleh Taratula of the OSU College of Pharmacy tackled the problem by developing nanoclusters, multiatom collections of nanoparticles, with enhanced heating efficiency. The nanoclusters are hexagon-shaped iron oxide nanoparticles doped with cobalt and manganese and loaded into biodegradable nanocarriers.

Findings were published in ACS Nano.

“There had been many attempts to develop nanoparticles that could be administered systemically in safe doses and still allow for hot enough temperatures inside the tumor,” said Olena Taratula, associate professor of pharmaceutical sciences. “Our new nanoplatform is a milestone for treating difficult-to-access tumors with magnetic hyperthermia. This is a proof of concept, and the nanoclusters could potentially be optimized for even greater heating efficiency.”

The nanoclusters’ ability to reach therapeutically relevant temperatures in tumors following a single, low-dose IV injection opens the door to exploiting the full potential of magnetic hyperthermia in treating cancer, either by itself or with other therapies, she added.

“It’s already been shown that magnetic hyperthermia at moderate temperatures increases the susceptibility of cancer cells to chemotherapy, radiation and immunotherapy,” Taratula said.

The mouse model in this research involved animals receiving IV nanocluster injections after ovarian tumors had been grafted underneath their skin.

“To advance this technology, future studies need to use orthotopic animal models – models where deep-seated tumors are studied in the location they would actually occur in the body,” she said. “In addition, to minimize the heating of healthy tissue, current AMF systems need to be optimized, or new ones developed.”

The National Institutes of Health, the OSU College of Pharmacy and Najran University of Saudi Arabia supported this research.

Also collaborating were OSU electrical engineering professor Pallavi Dhagat, postdoctoral scholars Xiaoning Li and Canan Schumann of the College of Pharmacy, pharmacy graduate students Hassan Albarqi, Fahad Sabei and Abraham Moses, engineering graduate student Mikkel Hansen, and pre-pharmacy undergrads Tetiana Korzun and Leon Wong.

Copyright © Oregon State University

Chemists could make ‘smart glass’ smarter by manipulating it at the nanoscale: Colorado State University


Smart glass 190604131210_1_540x360

Chemists have devised a potentially major improvement to both the speed and durability of smart glass by providing a better understanding of how the glass works at the nanoscale.

An alternative nanoscale design for eco-friendly smart glass

Source: Colorado State University
“Smart glass,” an energy-efficiency product found in newer windows of cars, buildings and airplanes, slowly changes between transparent and tinted at the flip of a switch.

“Slowly” is the operative word; typical smart glass takes several minutes to reach its darkened state, and many cycles between light and dark tend to degrade the tinting quality over time. Colorado State University chemists have devised a potentially major improvement to both the speed and durability of smart glass by providing a better understanding of how the glass works at the nanoscale.

They offer an alternative nanoscale design for smart glass in new research published June 3 in Proceedings of the National Academy of Sciences. The project started as a grant-writing exercise for graduate student and first author R. Colby Evans, whose idea — and passion for the chemistry of color-changing materials — turned into an experiment involving two types of microscopy and enlisting several collaborators. Evans is advised by Justin Sambur, assistant professor in the Department of Chemistry, who is the paper’s senior author.

The smart glass that Evans and colleagues studied is “electrochromic,” which works by using a voltage to drive lithium ions into and out of thin, clear films of a material called tungsten oxide. “You can think of it as a battery you can see through,” Evans said. Typical tungsten-oxide smart glass panels take 7-12 minutes to transition between clear and tinted.

The researchers specifically studied electrochromic tungsten-oxide nanoparticles, which are 100 times smaller than the width of a human hair. Their experiments revealed that single nanoparticles, by themselves, tint four times faster than films of the same nanoparticles. That’s because interfaces between nanoparticles trap lithium ions, slowing down tinting behavior. Over time, these ion traps also degrade the material’s performance.

To support their claims, the researchers used bright field transmission microscopy to observe how tungsten-oxide nanoparticles absorb and scatter light. Making sample “smart glass,” they varied how much nanoparticle material they placed in their samples and watched how the tinting behaviors changed as more and more nanoparticles came into contact with each other. They then used scanning electron microscopy to obtain higher-resolution images of the length, width and spacing of the nanoparticles, so they could tell, for example, how many particles were clustered together, and how many were spread apart.

Based on their experimental findings, the authors proposed that the performance of smart glass could be improved by making a nanoparticle-based material with optimally spaced particles, to avoid ion-trapping interfaces.

Their imaging technique offers a new method for correlating nanoparticle structure and electrochromic properties; improvement of smart window performance is just one application that could result. Their approach could also guide applied research in batteries, fuel cells, capacitors and sensors.

“Thanks to Colby’s work, we have developed a new way to study chemical reactions in nanoparticles, and I expect that we will leverage this new tool to study underlying processes in a wide range of important energy technologies,” Sambur said.

The paper’s co-authors include Austin Ellingworth, a former Research Experience for Undergraduates student from Winona State University; Christina Cashen, a CSU chemistry graduate student; and Christopher R. Weinberger, a professor in CSU’s Department of Mechanical Engineering

Story Source:

Materials provided by Colorado State University. Original written by Anne Manning. Note: Content may be edited for style and length.


Journal Reference:

  1. R. Colby Evans, Austin Ellingworth, Christina J. Cashen, Christopher R. Weinberger, Justin B. Sambur. Influence of single-nanoparticle electrochromic dynamics on the durability and speed of smart windowsProceedings of the National Academy of Sciences, 2019; 201822007 DOI: 10.1073/pnas.1822007116

 

Colorado State University. “Chemists could make ‘smart glass’ smarter by manipulating it at the nanoscale: An alternative nanoscale design for eco-friendly smart glass.” ScienceDaily. ScienceDaily, 4 June 2019. <www.sciencedaily.com/releases/2019/06/190604131210.htm>.

MIT: A better way to encapsulate islet cells for Diabetes Treatment – Prevents immune system Rejection of transplanted Pancreatic Islet Cells


MIT engineers have devised a way to incorporate crystallized immunosuppressant drugs into devices carrying encapsulated islet cells, which could allow them to be implanted as a long-term treatment for diabetes.

 

MIT engineers have devised a way to incorporate crystallized immunosuppressant drugs into devices carrying encapsulated islet cells, which could allow them to be implanted as a long-term 

 

Crystallized drug prevents immune system rejection of transplanted pancreatic islet cells.

 

When medical devices are implanted in the body, the immune system often attacks them, producing scar tissue around the device. This buildup of tissue, known as fibrosis, can interfere with the device’s function.

MIT researchers have now come up with a novel way to prevent fibrosis from occurring, by incorporating a crystallized immunosuppressant drug into devices. After implantation, the drug is slowly secreted to dampen the immune response in the area immediately surrounding the device.

“We developed a crystallized drug formulation that can target the key players involved in the implant rejection, suppressing them locally and allowing the device to function for more than a year,” says Shady Farah, an MIT and Boston Children’s Hospital postdoc and co-first author of the study, who is soon starting a new position as an assistant professor of the Wolfson Faculty of Chemical Engineering and the Russell Berrie Nanotechnology Institute at Technion-Israel Institute of Technology.

The researchers showed that these crystals could dramatically improve the performance of encapsulated islet cells, which they are developing as a possible treatment for patients with type 1 diabetes. Such crystals could also be applied to a variety of other implantable medical devices, such as pacemakers, stents, or sensors.

Former MIT postdoc Joshua Doloff, now an assistant professor of Biomedical and Materials Science Engineering and member of the Translational Tissue Engineering Center at Johns Hopkins University School of Medicine, is also a lead author of the paper, which appears in the June 24 issue of Nature Materials. Daniel Anderson, an associate professor in MIT’s Department of Chemical Engineering and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science (IMES), is the senior author of the paper.

Crystalline drug

Anderson’s lab is one of many research groups working on ways to encapsulate islet cells and transplant them into diabetic patients, in hopes that such cells could replace the patients’ nonfunctioning pancreatic cells and eliminate the need for daily insulin injections.

Fibrosis is a major obstacle to this approach, because scar tissue can block the islet cells’ access to the oxygen and nutrients. In a 2017 study, Anderson and his colleagues showed that systemic administration of a drug that blocks cell receptors for a protein called CSF-1 can prevent fibrosis by suppressing the immune response to implanted devices. This drug targets immune cells called macrophages, which are the primary cells responsible for initiating the inflammation that leads to fibrosis.

“That work was focused on identifying next-generation drug targets, namely which cell and cytokine players were essential for fibrotic response,” says Doloff, who was the lead author on that study, which also involved Farah. He adds, “After knowing what we had to target to block fibrosis, and screening drug candidates needed to do so, we still had to find a sophisticated way of achieving local delivery and release for as long as possible.”

In the new study, the researchers set out to find a way to load the drug directly into an implantable device, to avoid giving patients drugs that would suppress their entire immune system.

“If you have a small device implanted in your body, you don’t want to have your whole body exposed to drugs that are affecting the immune system, and that’s why we’ve been interested in creating ways to release drugs from the device itself,” Anderson says.

To achieve that, the researchers decided to try crystallizing the drugs and then incorporating them into the device. This allows the drug molecules to be very tightly packed, allowing the drug-releasing device to be miniaturized. Another advantage is that crystals take a long time to dissolve, allowing for long-term drug delivery. Not every drug can be easily crystallized, but the researchers found that the CSF-1 receptor inhibitor they were using can form crystals and that they could control the size and shape of the crystals, which determines how long it takes for the drug to break down once in the body.

“We showed that the drugs released very slowly and in a controlled fashion,” says Farah. “We took those crystals and put them in different types of devices and showed that with the help of those crystals, we can allow the medical device to be protected for a long time, allowing the device to keep functioning.”

Encapsulated islet cells

To test whether these drug crystalline formulations could boost the effectiveness of encapsulated islet cells, the researchers incorporated the drug crystals into 0.5-millimeter-diameter spheres of alginate, which they used to encapsulate the cells. When these spheres were transplanted into the abdomen or under the skin of diabetic mice, they remained fibrosis-free for more than a year. During this time, the mice did not need any insulin injections, as the islet cells were able to control their blood sugar levels just as the pancreas normally would.

“In the past three-plus years, our team has published seven papers in Nature journals — this being the seventh — elucidating the mechanisms of biocompatibility,” says Robert Langer, the David H. Koch Institute Professor at MIT and an author of the paper. “These include an understanding of the key cells and receptors involved, optimal implant geometries and physical locations in the body, and now, in this paper, specific molecules that can confer biocompatibility. Taken together, we hope these papers will open the door to a new generation of biomedical implants to treat diabetes and other diseases.”

The researchers believe that it should be possible to create crystals that last longer than those they studied in these experiments, by altering the structure and composition of the drug crystals. Such formulations could also be used to prevent fibrosis of other types of implantable devices. In this study, the researchers showed that crystalline drug could be incorporated into PDMS, a polymer frequently used for medical devices, and could also be used to coat components of a glucose sensor and an electrical muscle stimulation device, which include materials such as plastic and metal.

“It wasn’t just useful for our islet cell therapy, but could also be useful to help get a number of different devices to work long-term,” Anderson says.

The research was funded by JDRF, the National Institutes of Health, the Leona M. and Harry B. Helmsley Charitable Trust Foundation, and the Tayebati Family Foundation.

Other authors of the paper include MIT Principal Research Scientist Peter Muller; MIT grad students Atieh Sadraei and Malia McAvoy; MIT research affiliate Hye Jung Han; former MIT postdoc Katy Olafson; MIT technical associate Keval Vyas; former MIT grad student Hok Hei Tam; MIT postdoc Piotr Kowalski; former MIT undergraduates Marissa Griffin and Ashley Meng; Jennifer Hollister-Locke and Gordon Weir of the Joslin Diabetes Center; Adam Graham of Harvard University; James McGarrigle and Jose Oberholzer of the University of Illinois at Chicago; and Dale Greiner of the University of Massachusetts Medical School.

Lawrence Berkeley National Lab scientists grow spiraling new Crystal material Which could yield unique optical, electronic and thermal properties, including super conductivity SuperChem


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UC Berkeley and Berkeley Lab researchers created a new crystal built of a spiraling stack of atomically thin 

UC Berkeley and Berkeley Lab researchers created a new crystal built of a spiraling stack of atomically thin germanium sulfide sheets. Credit: UC Berkeley image by Yin Liu

With a simple twist of the fingers, one can create a beautiful spiral from a deck of cards. In the same way, scientists at the University of California, Berkeley, and Lawrence Berkeley National Laboratory (Berkeley Lab) have created new inorganic crystals made of stacks of atomically thin sheets that unexpectedly spiral like a nanoscale card deck.

Their surprising structures, reported in a new study appearing online Wednesday, June 20, in the journal Nature, may yield unique optical, electronic and thermal properties, including superconductivity, the researchers say.

These helical crystals are made of stacked layers of germanium sulfide, a semiconductor material that, like graphene, readily forms sheets that are only a few atoms or even a single atom thick. Such “nanosheets” are usually referred to as “2-D materials.”

“No one expected 2-D materials to grow in such a way. It’s like a surprise gift,” said Jie Yao, an assistant professor of materials science and engineering at UC Berkeley. “We believe that it may bring great opportunities for materials research.”

While the shape of the crystals may resemble that of DNA, whose helical structure is critical to its job of carrying genetic information, their underlying structure is actually quite different. Unlike “organic” DNA, which is primarily built of familiar atoms like carbon, oxygen and hydrogen, these “inorganic” crystals are built of more far-flung elements of the periodic table—in this case, sulfur and germanium. And while organic molecules often take all sorts of zany shapes, due to unique properties of their primary component, carbon, inorganic molecules tend more toward the straight and narrow.

To create the twisted structures, the team took advantage of a crystal defect called a screw dislocation, a “mistake” in the orderly crystal structure that gives it a bit of a twisting force. This “Eshelby Twist,” named after scientist John D. Eshelby, has been used to create nanowires that spiral like pine trees. But this study is the first time the Eshelby Twist has been used to make crystals built of stacked 2-D layers of an atomically thin semiconductor.

1-crystalwitha

The helical crystals may yield surprising new properties, like superconductivity. Credit: UC Berkeley image by Yin Liu

“Usually, people hate defects in a material—they want to have a perfect crystal,” said Yao, who also serves as a faculty scientist at Berkeley Lab. “But it turns out that, this time, we have to thank the defects. They allowed us to create a natural twist between the material layers.”

In a major discovery last year, scientists reported that graphene becomes superconductive when two atomically thin sheets of the material are stacked and twisted at what’s called a “magic angle.” While other researchers have succeeded at stacking two layers at a time, the new paper provides a recipe for synthesizing stacked structures that are hundreds of thousands or even millions of layers thick in a continuously twisting fashion.

“We observed the formation of discrete steps in the twisted crystal, which transforms the smoothly twisted crystal to circular staircases, a new phenomenon associated with the Eshelby Twist mechanism,” said Yin Liu, co-first author of the paper and a graduate student in materials science and engineering at UC Berkeley. “It’s quite amazing how interplay of materials could result in many different, beautiful geometries.”

By adjusting the material synthesis conditions and length, the researchers could change the angle between the layers, creating a twisted structure that is tight, like a spring, or loose, like an uncoiled Slinky. And while the research team demonstrated the technique by growing helical crystals of germanium sulfide, it could likely be used to grow layers of other materials that form similar atomically thin layers.

“The twisted structure arises from a competition between stored energy and the energy cost of slipping two material layers relative to one another,” said Daryl Chrzan, chair of the Department of Materials Science and Engineering and senior theorist on the paper. “There is no reason to expect that this competition is limited to germanium sulfide, and similar structures should be possible in other 2-D material systems.”

“The twisted behavior of these layered materials, typically with only two layers twisted at different angles, has already showed great potential and attracted a lot of attention from the physics and chemistry communities. Now, it becomes highly intriguing to find out, with all of these twisted layers combined in our new material, if will they show quite different material properties than regular stacking of these materials,” Yao said. “But at this moment, we have very limited understanding of what these properties could be, because this form of material is so new. New opportunities are waiting for us.”

Explore further

Research team discovers perfectly imperfect twist on nanowire growth

 

Graphene-based ink may lead to printable energy storage devices


Top) The salt-templated process of synthesizing graphene nanosheets into ink. (Bottom) The ink and printed demonstration. Credit: Wei et al. ©2019 American Chemical Society

Researchers have created an ink made of graphene nanosheets, and demonstrated that the ink can be used to print 3-D structures. As the graphene-based ink can be mass-produced in an inexpensive and environmentally friendly manner, the new methods pave the way toward developing a wide variety of printable energy storage devices.

The researchers, led by Jingyu Sun and Zhongfan Liu at Soochow University and the Beijing Graphene Institute, and Ya-yun Li at Shenzhen University, have published a paper on their work in a recent issue of ACS Nano.

“Our work realizes the scalable and green synthesis of nitrogen-doped  nanosheets on a salt template by direct chemical vapor deposition,” Sun told Phys.org. “This allows us to further explore thus-derived inks in the field of printable energy storage.”

As the scientists explain, a key goal in graphene research is the mass production of graphene with high quality and at low cost. Energy-storage applications typically require graphene in powder form, but so far production methods have resulted in powders with a large number of structural defects and chemical impurities, as well as nonuniform layer thickness. This has made it difficult to prepare high-quality graphene inks.

In the new paper, the researchers have demonstrated a new method for preparing graphene inks that overcomes these challenges. The method involves growing nitrogen-doped graphene nanosheets over NaCl crystals using direct chemical vapor deposition, which causes molecular fragments of nitrogen and carbon to diffuse on the surface of the NaCl crystals. The researchers chose NaCl due to its natural abundance and low cost, as well as its water solubility.

To remove the NaCl, the coated crystals are submerged in water, which causes the NaCl to dissolve and leave behind pure nitrogen-doped graphene cages. In the final step, treating the cages with ultrasound transforms the cages into 2-D nanosheets, each about 5-7 graphite layers thick.

The resulting nitrogen-doped graphene nanosheets have relatively few defects and an ideal size (about 5 micrometers in side length) for printing, as larger flakes can block the nozzle.

To demonstrate the nanosheets’ effectiveness, the researchers printed a wide variety of 3-D structures using inks based on the graphene sheets.

Among their demonstrations, the researchers used the ink as a conductive additive for an  (vanadium nitride) and used the composite ink to print flexible electrodes for supercapacitors with high power density and good cyclic stability. 

In a second demonstration, the researchers created a composite ink made of the graphene sheets along with binder material (polypropylene) for printing interlayers for Li−S batteries.

Compared to batteries with separators made only of the conventional material, those made with the composite material exhibited enhanced conductivity, leading to an overall improvement in battery performance.

“In the future, we plan to exploit the direct technique for the mass production of high-quality graphene powders toward emerging printable energy storage applications,” Sun said.

More information: Nan Wei et al. “Scalable Salt-Templated Synthesis of Nitrogen-Doped Graphene Nanosheets toward Printable Energy Storage.” ACS Nano. DOI: 10.1021/acsnano.9b03157

Journal information: ACS Nano