Scientists discover mechanism that causes cancer cells to self-destruct


Many cancer patients struggle with the adverse effects of chemotherapy, still the most prescribed cancer treatment. For patients with pancreatic cancer and other aggressive cancers, the forecast is more grim: there is no known effective therapy.

A new Tel Aviv University study published last month in Oncotarget discloses the role of three proteins in killing fast-duplicating cancer cells while they’re dividing. The research, led by Prof. Malka Cohen-Armon of TAU’s Sackler School of Medicine, finds that these proteins can be specifically modified during the division process—mitosis—to unleash an inherent “death mechanism” that self-eradicates duplicating cancer cells.

“The discovery of an exclusive mechanism that kills cancer cells without impairing healthy cells, and the fact that this mechanism works on a variety of rapidly proliferating human cancer cells, is very exciting,” Prof. Cohen-Armon said. 
“According to the mechanism we discovered, the faster cancer cells proliferate, the faster and more efficiently they will be eradicated. The mechanism unleashed during mitosis may be suitable for treating aggressive cancers that are unaffected by traditional chemotherapy.

“Our experiments in cell cultures tested a variety of incurable human cancer types—breast, lung, ovary, colon, pancreas, blood, brain,” Prof. Cohen-Armon continued. “This discovery impacts existing cancer research by identifying a new specific target mechanism that exclusively and rapidly eradicates cancer cells without damaging normally proliferating human cells.”

The research was conducted in collaboration with Prof. Shai Izraeli and Dr. Talia Golan of the Cancer Research Center at Sheba Medical Center, Tel Hashomer, and Prof. Tamar Peretz, head of the Sharett Institute of Oncology at Hadassah Medical Center, Ein Kerem.

A new target for cancer research

The newly-discovered mechanism involves the modification of specific proteins that affect the construction and stability of the spindle, the microtubular structure that prepares duplicated chromosomes for segregation into “daughter” cells during cell division.

The researchers found that certain compounds called Phenanthridine derivatives were able to impair the activity of these proteins, which can distort the spindle structure and prevent the segregation of chromosomes. Once the proteins were modified, the cell was prevented from splitting, and this induced the cell’s rapid self-destruction.

“The mechanism we identified during the mitosis of cancer cells is specifically targeted by the Phenanthridine derivatives we tested,” Prof. Cohen-Armon said. “However, a variety of additional drugs that also modify these specific proteins may now be developed for cancer cell self-destruction during cell division. The faster the cancer cells proliferate, the more quickly they are expected to die.”

Research was conducted using both cancer cell cultures and mice transplanted with human cancer cells. The scientists harnessed biochemical, molecular biology and imaging technologies to observe the mechanism in real time. In addition, mice transplanted with triple negative breast cancer cells, currently resistant to available therapies, revealed the arrest of tumor growth.

“Identifying the mechanism and showing its relevance in treating developed tumors opens new avenues for the eradication of rapidly developing aggressive cancers without damaging healthy tissues,” said Prof. Cohen-Armon.
The researchers are currently investigating the potential of one of the Phenanthridine derivatives to treat two aggressive cancers known to be unresponsive to current chemotherapy: pancreatic cancer and triple negative breast cancer.

More information: Leonid Visochek et al, Exclusive destruction of mitotic spindles in human cancer cells, Oncotarget (2017). DOI: 10.18632/oncotarget.15343

Provided by: Tel Aviv University

MIT: New kind of supercapacitor made without carbon


MIT-Supercapacitor_0 032417

To demonstrate the supercapacitor’s ability to store power, the researchers modified an off-the-shelf hand-crank flashlight (the red parts at each side) by cutting it in half and installing a small supercapacitor in the center, in a conventional button battery case, seen at top. When the crank is turned to provide power to the flashlight, the light continues to glow long after the cranking stops, thanks to the stored energy. Photo: Melanie Gonick

Energy storage device could deliver more power than current versions of this technology.

Energy storage devices called supercapacitors have become a hot area of research, in part because they can be charged rapidly and deliver intense bursts of power. However, all supercapacitors currently use components made of carbon, which require high temperatures and harsh chemicals to produce.

Now researchers at MIT and elsewhere have for the first time developed a supercapacitor that uses no conductive carbon at all, and that could potentially produce more power than existing versions of this technology.

The team’s findings are being reported in the journal Nature Materials, in a paper by Mircea Dincă, an MIT associate professor of chemistry; Yang Shao-Horn, the W.M. Keck Professor of Energy; and four others.

“We’ve found an entirely new class of materials for supercapacitors,” Dincă says.

Dincă and his team have been exploring for years a class of materials called metal-organic frameworks, or MOFs, which are extremely porous, sponge-like structures. These materials have an extraordinarily large surface area for their size, much greater than the carbon materials do. That is an essential characteristic for supercapacitors, whose performance depends on their surface area. But MOFs have a major drawback for such applications: They are not very electrically conductive, which is also an essential property for a material used in a capacitor.

“One of our long-term goals was to make these materials electrically conductive,” Dincă says, even though doing so “was thought to be extremely difficult, if not impossible.” But the material did exhibit another needed characteristic for such electrodes, which is that it conducts ions (atoms or molecules that carry a net electric charge) very well.

“All double-layer supercapacitors today are made from carbon,” Dincă says. “They use carbon nanotubes, graphene, activated carbon, all shapes and forms, but nothing else besides carbon. So this is the first noncarbon, electrical double-layer supercapacitor.”

One advantage of the material used in these experiments, technically known as Ni3(hexaiminotriphenylene)2, is that it can be made under much less harsh conditions than those needed for the carbon-based materials, which require very high temperatures above 800 degrees Celsius and strong reagent chemicals for pretreatment.

The team says supercapacitors, with their ability to store relatively large amounts of power, could play an important role in making renewable energy sources practical for widespread deployment. They could provide grid-scale storage that could help match usage times with generation times, for example, or be used in electric vehicles and other applications.

The new devices produced by the team, even without any optimization of their characteristics, already match or exceed the performance of existing carbon-based versions in key parameters, such as their ability to withstand large numbers of charge/discharge cycles. Tests showed they lost less than 10 percent of their performance after 10,000 cycles, which is comparable to existing commercial supercapacitors.

But that’s likely just the beginning, Dincă says. MOFs are a large class of materials whose characteristics can be tuned to a great extent by varying their chemical structure. Work on optimizing their molecular configurations to provide the most desirable attributes for this specific application is likely to lead to variations that could outperform any existing materials. “We have a new material to work with, and we haven’t optimized it at all,” he says. “It’s completely tunable, and that’s what’s exciting.”

While there has been much research on MOFs, most of it has been directed at uses that take advantage of the materials’ record porosity, such as for storage of gases. “Our lab’s discovery of highly electrically conductive MOFs opened up a whole new category of applications,” Dincă says. Besides the new supercapacitor uses, the conductive MOFs could be useful for making electrochromic windows, which can be darkened with the flip of a switch, and chemoresistive sensors, which could be useful for detecting trace amounts of chemicals for medical or security applications.

While the MOF material has advantages in the simplicity and potentially low cost of manufacturing, the materials used to make it are more expensive than conventional carbon-based materials, Dincă says. “Carbon is dirt cheap. It’s hard to find anything cheaper.” But even if the material ends up being more expensive, if its performance is significantly better than that of carbon-based materials, it could find useful applications, he says.

This discovery is “very significant, from both a scientific and applications point of view,” says Alexandru Vlad, a professor of chemistry at the Catholic University of Louvain in Belgium, who was not involved in this research. He adds that “the supercapacitor field was (but will not be anymore) dominated by activated carbons,” because of their very high surface area and conductivity. But now, “here is the breakthrough provided by Dinca et al.: They could design a MOF with high surface area and high electrical conductivity, and thus completely challenge the supercapacitor value chain! There is essentially no more need of carbons for this highly demanded technology.”

And a key advantage of that, he explains, is that “this work shows only the tip of the iceberg. With carbons we know pretty much everything, and the developments over the past years were modest and slow. But the MOF used by Dinca is one of the lowest-surface-area MOFs known, and some of these materials can reach up to three times more [surface area] than carbons. The capacity would then be astonishingly high, probably close to that of batteries, but with the power performance [the ability to deliver high power output] of supercapacitors.”

The research team included former MIT postdoc Dennis Sheberla (now a postdoc at Harvard University), MIT graduate student John Bachman, Joseph Elias PhD ’16, and Cheng-Jun Sun of Argonne National Laboratory. The work was supported by the U.S. Department of Energy through the Center for Excitonics, the Sloan Foundation, the Research Corporation for Science Advancement, 3M, and the National Science Foundation.

Powerful hybrid storage system combines advantages of lithium-ion batteries and Supercapacitors – “What Comes Next”


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A battery that can be charged in seconds, has a large capacity and lasts ten to twelve years? Certainly, many have wanted such a thing. Now the FastStorageBW II project – which includes Fraunhofer – is working on making it a reality. Fraunhofer researchers are using pre-production to optimize large-scale production and ensure it follows the principles of Industrie 4.0 from the outset.

Imagine you’ve had a hectic day and then, to cap it all, you find that the battery of your electric vehicle is virtually empty. This means you’ll have to take a long break while it charges fully. It’s a completely different story with capacitors, which charge in seconds. However, they have a different drawback: they store very little energy.electric cars images

In the FastStorageBW II project, funded by the Baden-Württemberg Ministry of Economic Affairs, researchers from the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, together with colleagues from the battery manufacturer VARTA AG and other partners, are developing a powerful hybrid storage system that combines the advantages of lithium-ion batteries and .

“The PowerCaps have a specific capacity as high as lead batteries, a long life of ten to twelve years, and charge in a matter of seconds like a supercapacitor,” explains Joachim Montnacher, Head of the Energy business unit at Fraunhofer IPA. What’s more, PowerCaps can operate at temperatures of up to 85 degree Celsius. They withstand a hundred times more charge cycles than conventional battery systems and retain their charge over several weeks without any significant losses due to self-discharge.

Elon+Musk+cVLpwWp3rxJmAlso Read About: Supercapacitor breakthrough suggests EVs could charge in seconds but with a trade-off

“Supercapacitors may be providing an alternative to electric-car batteries sooner than expected, according to a new research study. Currently, supercapacitors can charge and discharge rapidly over very large numbers of cycles, but their poor energy density per kilogram —- at just one twentieth of existing battery technology — means that they can’t compete with batteries in most applications. That’s about to change, say researchers from the University of Surrey and University of Bristol in conjunction with Augmented Optics.

Large-scale production with minimum risk

The Fraunhofer IPA researchers’ main concern is with manufacturing: to set up new battery production, it is essential to implement the relevant process knowledge in the best possible way.

After all, it costs millions of euros to build a complete manufacturing unit. “We make it possible for battery manufacturers to install an intermediate step – a small-scale production of sorts – between laboratory production and large-scale production,” says Montnacher. “This way, we can create ideal conditions for large-scale production, optimize processes and ensure production follows the principles of Industrie 4.0 from the outset. Because in the end, that will give companies a competitive advantage.” Another benefit is that this cuts the time it takes to ramp up production by more than 50 percent.

For this innovative small-scale production setup, researchers cleverly combine certain production sequences. However, not all systems are connected to each other – at least, as far as the hardware is concerned. More often, it is an employee that carries the batches from one machine to the next. Ultimately, it is about developing a comprehensive understanding of the process, not about producing the greatest number of in the shortest amount of time. For example, this means clarifying questions such as if the desired quality can be reproduced. The systems are designed as flexibly as possible so that they can be used for different production variations.

Making large-scale production compatible with Industrie 4.0

As far as software is concerned, the systems are thoroughly connected. Like process clusters, they are also equipped with numerous sensors, which show the clusters what data to capture for each of the process steps. They communicate with one another and store the results in a cloud. Researchers and entrepreneurs can then use this data to quickly analyze which factors influence the quality of the product – Does it have Industrie 4.0 capability? Were the right sensors selected? Do they deliver the desired data? Where are adjustments required?

Fraunhofer IPA is also applying its expertise beyond the area of production technology: The scientists are developing business models for the marketing of cells, they are analyzing resource availability, and they are optimizing the subsequent recycling of PowerCaps.

Explore further: Virtual twin controls production

Provided by: Fraunhofer-Gesellschaft

Watch a YouTube Video in ‘Next Generation’ Energy-Dense Si-Nanowire Batteries

 

 

Quantum Dots ~ “On the Move” ~ Illuminating Applications for photovoltaic cells, computers and drug delivery


The quantum dots used by the researchers are particles of semi-conducting material just a few nanometres wide, and are the subject of great interest because of their potential for use in photovoltaic cells or computers.

“The great thing about these particles is that they absorb light and emit it in a different colour,” explains research leader Lukas Kapitein. “We use that characteristic to follow their movements through the cell with a microscope.”

But to do so, the quantum dots had to be inserted into the cell. Most current techniques result in dots that are inside microscopic vesicles surrounded by a membrane, but this prevents them from moving freely.

However, the researchers succeeded directly delivering the particles into cultured cells by applying a strong electromagnetic field that created transient openings in the cell membrane.

In their article (“Probing cytoskeletal modulation of passive and active intracellular dynamics using nanobody-functionalized quantum dots”), they describe how this electroporation process allowed them to insert the quantum dots inside the cell.

The various transport processes that can be Sstudied using quantum dots

The various transport processes that can be Sstudied using quantum dots. Cyan: rapid diffusion. Red: slow diffusion in an actin network. Green: active transport by motor proteins. (Image: Anna Vinokurova)

Extremely bright

Once inserted, the quantum dots begin to move under the influence of diffusion. Kapitein: “Since Einstein, we have known that the movement of visible particles can provide information about the characteristics of the solution in which they move.

“Previous research has shown that particles move fairly slowly inside the cell, which indicates that the cytoplasm is a viscous fluid. But because our particles are extremely bright, we could film them at high speed, and we observed that many particles also make much faster movements that had been invisible until now.

“We recorded the movements at 400 frames per minute, more than 10 times faster than normal video. At that measurement speed, we observed that some quantum dots do in fact move very slowly, but others can be very fast.”

Kapitein is especially interested in the spatial distribution between the slow and fast quantum dots: at the edges of the cell, the fluid seems to be very viscous, but deeper in the cell he observed much faster particles.

Kapitein: “We have shown that the slow movement occurs because the particles are caught in a dynamic network of protein tubules called actin filaments, which are more common near the cell membrane. So the particles have to move through the holes in that network.”

Motor proteins

In addition to studying this passive transport process, the researchers have developed a technique for actively moving the quantum dots by binding them to a variety of specific motor proteins. 
These motor proteins move along microtubuli, the other filaments in the cytoskeleton, and are responsible for transport within the cell.

This allowed them to study how this transport is influenced by the dense layout of the actin network near the cell membrane. They observed that this differs for different types of motor protein, because they move along different types of microtubuli.

Kapitein: “Active and passive transport are both very important for the functioning of the cell, so several different physics models have been proposed for transport within the cell. Our results show that such physical models must take the spatial variations in the cellular composition into consideration as well.”

Source: Utrecht University

PNNL: ‘Composing and De-Composing’ with designer molecules at the nano scale for better Batteries/ Energy Storage 



Designed at Pacific Northwest National Laboratory, the device lets scientists add designer molecules to an extremely well-defined electrochemical cell. They can then characterize the electrode-electrolyte interface while the cell is charged and discharged at technologically relevant conditions. (Image: Mike Perkins, PNNL

Whether inside your laptop computer or storing energy outside wind farms, we need high-capacity, long-lasting, and safe batteries. In batteries, as in any electrochemical device, critical processes happen where the electrolyte and active material meet at the solid electrode.

However, determining what happens at the meeting point has been difficult because in addition to active molecules, interfaces often contain numerous inactive components.

Led by Laboratory Fellow Dr. Julia Laskin, scientists at Pacific Northwest National Laboratory have now found a way to carefully design technologically important interfaces by soft landing active molecules onto a small solid-state electrochemical cell. 

They packed the electrolyte into a solid membrane, deposited active ions on top, and characterized the cell using traditional electrochemical techniques. The device they built allows them to study key reactions in real time in controlled gaseous environments (PNAS, “In Situ Solid-State Electrochemistry of Mass-Selected Ions at Well-Defined Electrode-Electrolyte Interfaces”).

“To increase performance, we need to study what takes place inside batteries or fuel cells— understand processes at the interface in real time as the reactions are happening,” said Dr. Venkateshkumar Prabhakaran, first author of the study.

The device provides a way to understand the basic breakdown reactions, material build-up, and other processes at the electrode surface during operation. Being able to gather this dynamic information is vital to building better batteries, fuel cells, and other energy devices. 
It also matters in improving the efficiency of industrial processes through electrocatalysis. “We are doing fundamental research on state-of-the-art technologically relevant interfaces,” said Laskin.

Methods

At PNNL, scientists designed an electrochemical device to study the electrode-electrolyte interface in real time. The device uses a solid ionic-liquid membrane, in vacuum or other well-controlled environments, that has transport properties similar to a liquid electrolyte.

The solid membrane lets the team modify the electrolyte interface using ion soft-landing techniques. With soft landing, they place well-characterized active molecules at the interface. These molecules include catalytic metal clusters and redox-active “molecular battery” species capable of holding large numbers of electrons—potential candidates for boosting battery capacity.

In an exciting new twist, scientists can also add molecular fragments to the cell. They create the fragment ions by “smashing” precursor molecules in the gas phase. These gas-phase fragments may then be selected and added to the membrane. The result is a well-defined film that you can’t typically make in solution. “This gives us access to a broad range of species that aren’t stable under normal conditions and enables us to understand the contribution of individual building blocks to the overall activity of parent molecules,” said Dr. Grant Johnson, a PNNL chemist and member of the team.

When the soft-landed clusters diffuse through the extremely thin membrane and reach the electrode surface of the newly designed device, the team has a detailed and precisely defined active species they can examine using several electrochemical and spectroscopic techniques. Once at the interface, the team can study how the active molecules change the transport of electrons, increasing capacity or depleting it, for example.

What’s Next? 

The researchers are using the device to study how soft-landed noble metal clusters modify carbon dioxide to upgrade this common pollutant to more valuable chemical feedstocks.

Source: Pacific Northwest National Laboratory

Storing solar energy -in ‘liquid form’ ~ Video



Researchers at Chalmers University of Technology in Sweden have demonstrated efficient solar energy storage in a chemical liquid. The stored energy can be transported and then released as heat whenever needed. 

The research is now presented on the cover of the scientific journal Energy & Environmental Science (“Exploring the potential of a hybrid device combining solar water heating and molecular solar thermal energy storage”).

Many consider the sun the energy source of the future. But one challenge is that it is difficult to store solar energy and deliver the energy ‘on demand’.

A research team from Chalmers University of Technology in Gothenburg, Sweden, has shown that it is possible to convert the solar energy directly into energy stored in the bonds of a chemical fluid – a so-called molecular solar thermal system. 

The liquid chemical makes it possible to store and transport the stored solar energy and release it on demand, with full recovery of the storage medium. The process is based on the organic compound norbornadiene that upon exposure to light converts into quadricyclane.

‘The technique means that that we can store the solar energy in chemical bonds and release the energy as heat whenever we need it.’ says Professor Kasper Moth-Poulsen, who is leading the research team. ‘Combining the chemical energy storage with water heating solar panels enables a conversion of more than 80 percent of the incoming sunlight.’

Wallenberg Academy Fellow Kasper Moth-Poulsen, Chalmers University of Technology, is developing a promising new concept using artificial molecules that can capture, store and release solar energy, so that it can be used when the sun is not shining.

The research project was initiated at Chalmers more than six years ago and the research team contributed in 2013 to a first conceptual demonstration. 

At the time, the solar energy conversion efficiency was 0.01 percent and the expensive element ruthenium played a major role in the compound. Now, four years later, the system stores 1.1 percent of the incoming sunlight as latent chemical energy – an improvement of a factor of 100. 

Also, ruthenium has been replaced by much cheaper carbon-based elements.

‘We saw an opportunity to develop molecules that make the process much more efficient,’ says Moth-Poulsen. ‘At the same time, we are demonstrating a robust system that can sustain more than 140 energy storage and release cycles with negligible degradation.’

Source: Chalmers University of Technology

New nanosensor of Silk could speed development of new infrastructure; Aerospace and Consumer Materials 



Silk nanosensor could speed development of new infrastructure, aerospace and consumer materials (Middle) Mechanophore-labeled silk fiber fluoresces in response to damage or stress. (Right) Control sample without the mechanophore. (Image: Chelsea Davis and Jeremiah Woodcock/NIST)

Posted: Mar 17, 2017

Consumers want fuel-efficient vehicles and high-performance sporting goods, municipalities want weather-resistant bridges, and manufacturers want more efficient ways to make reliable cars and aircraft. 
What’s needed are new lightweight, energy-saving composites that won’t crack or break even after prolonged exposure to environmental or structural stress. 

To help make that possible, researchers working at the National Institute of Standards and Technology (NIST) have developed a way to embed a nanoscale damage-sensing probe into a lightweight composite made of epoxy and silk.

The probe, known as a mechanophore, could speed up product testing and potentially reduce the amount of time and materials needed for the development of many kinds of new composites.

The NIST team created their probe from a dye known as rhodamine spirolactam (RS), which changes from a dark state to a light state in reaction to an applied force. In this experiment, the molecule was attached to silk fibers contained inside an epoxy-based composite. 

As more and more force was applied to the composite, the stress and strain activated the RS, causing it to fluoresce when excited with a laser. Although the change was not visible to the naked eye, a red laser and a microscope built and designed by NIST were used to take photos inside the composite, showing even the most minute breaks and fissures to its interior, and revealing points where the fiber had fractured.

The results were published today in the journal Advanced Materials Interfaces (“Observation of Interfacial Damage in a Silk-Epoxy Composite, Using a Simple Mechanoresponsive Fluorescent Probe”).

The materials used in the design of composites are diverse. In nature, composites such as crab shell or elephant tusk (bone) are made of proteins and polysaccharides. In this study, epoxy was combined with silk filaments prepared by Professor Fritz Vollrath’s group at Oxford University using Bombyx mori silk worms. Fiber-reinforcedpolymer composites such as the one used in this study combine the most beneficial aspects of the main components–the strength of the fiber and the toughness of the polymer.

What all composites have in common, though, is the presence of an interface where the components meet. The resilience of that interface is critical to a composite’s ability to withstand damage. Interfaces that are thin but flexible are often favored by designers and manufacturers, but it is very challenging to measure the interfacial properties in a composite.

“There have long been ways to measure the macroscopic properties of composites,” said researcher Jeffrey Gilman, who led the team doing the work at NIST. “But for decades the challenge has been to determine what was happening inside, at the interface.”

One option is optical imaging. However, conventional methods for optical imaging are only able to record images at scales as small as 200-400 nanometers. Some interfaces are only 10 to 100 nanometers in thickness, making such techniques somewhat ineffective for imaging the interphase in composites. 

By installing the RS probe at the interface, the researchers were able to “see” damage exclusively at the interface using optical microscopy.

The NIST research team is planning to expand their research to explore how such probes could be used in other kinds of composites as well. They also would like to use such sensors to enhance the capability of these composites to withstand extreme cold and heat. 
There’s a tremendous demand for composites that can withstand prolonged exposure to water, too, especially for use in building more resilient infrastructure components such as bridges and giant blades for wind turbines.

The research team plans to continue searching for more ways that damage sensors such as the one in this study could be used to improve standards for existing composites and create new standards for the composites of the future, ensuring that those materials are safe, strong and reliable.

“We now have a damage sensor to help optimize the composite for different applications,” Gilman said. “If you attempt a design change, you can figure out if the change you made improved the interface of a composite, or weakened it.”

Source: National Institute of Standards and Technology (NIST)

Science in 360°: Say ‘hello’ to HERMAN, The Nanoparticle Robot: Video


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Published on Mar 7, 2017
Science in 360°: Say hello to HERMAN, a robot that accelerates the synthesis of nanoparticles for a wide range of cool applications such as biosensors, smart window coatings, and display technologies. HERMAN (aka High-throughput Experimentation Robot for the Multiplexed Automation of Nanochemistry) is a one-of-a-kind robot at Berkeley Lab’s Molecular Foundry that brings parallel processing and an extreme level of precision to the materials discovery process.

Using Nanotechnology to Control the formation of ice on surfaces


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Control of ice growth kinetics. (A) Hexagonal ice composed by two basal facets (c-axis) and six prism facets (a-axis). (B) Random and aligned orientations of c-axes were found on trapezoid-shaped microgrooves (TMG) and V-shaped microgrooves (VMG) surfaces, respectively. (C) Ice embryos appear on the side walls, the edges, and the valleys of groove on TMG surfaces, resulting in different orientations of ice crystals. On the other hand, an ice embryo forms only at the valley of grooves on the VMG surface, leading to the confined ice orientation. Scale bars are 15 µm. (Reprinted with permission by American Chemical Society) (click on image to enlarge)

In recent years, researchers working on de-icing and anti-icing strategies have been inspired by biology and nanotechnology to develop nanocoatings and other nanostructured surfaces.

Researchers now have demonstrated the ability to spatially control frost nucleation (ice formation from water vapor) and to manipulate ice crystal growth kinetics.”The spatial control of icing in the condensation-freezing process and through the coating of hydrophilic materials has been demonstrated before,” Ming-Chang Lu, Associate Professor in the Department of Mechanical Engineering at National Chiao Tung University said, “However, the ice nucleation control and the confinement of ice crystal growth direction through manipulating roughness scale have not been reported in the literature.”

In previous work, Lu and his team demonstrated that heterogeneous nucleation of condensation could be spatially controlled by manipulating roughness scale (Advanced Functional Materials, “Spatial Control of Heterogeneous Nucleation on the Superhydrophobic Nanowire Array”).

 

ricedeicerga-052416Read more About Nanotechnology and Deicing

Rice University: Graphene Nano-Ribbons Demonstrate Deicing Capabilities: Dr. James Tour

 

 

 

 

This motivated them to further explore whether the same control could be achieved in the icing process.Indeed, as they recently have reported in ACS Nano (“Control of Ice Formation”), they found that a surface’s anti-icing (preventing ice formation) and deicing performances could be promoted through the control of nucleation and the confinement of the ice crystal growth direction.The scientists achieved control of nucleation and the confinement of the crystal growth kinetics by manipulating local free energy barrier for nucleation.Moreover, the growth kinetics of ice can also be altered by adjusting the shape of the microgroove of the surface: Ice stacked along the direction of the V-shaped microgroove, whereas it grew in random directions on the trapezoid-shaped microgroove.As the researchers demonstrate in their paper, the spatial control of frost formation and the confinement of ice-growing kinetics improved the anti-icing and deicing performances.”We have shown that ice formation and ice crystal growth could be manipulated by tailoring surface roughness scale,” notes Lu.

 

“We believe that our results could be potentially applied to alleviate the icing issues in many industrial systems, such as, power transmission system, telecommunication system, heat exchangers, aircraft, etc.”In this work, the team systematically investigated – under an environmental scanning electron microscope (ESEM) – frosting and deicing processes on a plain silicon surface, a silicon nanowire (SiNW) array-coated surface, and V-shaped and trapezoid-shaped microgroove patterned surfaces.Nucleation is the first step of the phase transition during freezing. The team’s goal is to gain complete control of the ice formation process including nucleation, crystal growth, and ice spreading.”The results we demonstrated were on a Si surface and on a laboratory chip; in my opinion, the future directions are to explore whether the phenomena could be realized on other materials and on a larger system,” concludes Lu. “The ultimate goal is to have fully controls of icing and deicing processes. Therefore, it could be applied to alleviate the adverse effect caused by global warming, e.g., the loss of ice sheets.”

Original Post by Micheal Berger

Gold foil discovery could lead to wearable technology – Flexibility is the Key


goldfoildiscAn example of a gold foil peeled from single crystal silicon. Credit: Reprinted with permission from Naveen Mahenderkar et al., Science [355]:[1203] (2017).

Some day, your smartphone might completely conform to your wrist, and when it does, it might be covered in pure gold, thanks to researchers at Missouri University of Science and Technology.

Writing in the March 17 issue of the journal Science, the Missouri S&T researchers say they have developed a way to “grow” thin layers of gold on single crystal wafers of silicon, remove the gold foils, and use them as substrates on which to grow other electronic materials.

wearable-textiles-100616-0414_powdes_ti_f1The research team’s discovery could revolutionize wearable or “flexible” technology research, greatly improving the versatility of such electronics in the future.

According to lead researcher Dr. Jay A. Switzer, the majority of research into wearable technology has been done using polymer substrates, or substrates made up of multiple crystals. “And then they put some typically organic semiconductor on there that ends up being flexible, but you lose the order that (silicon) has,” says Switzer, Donald L. Castleman/FCR Endowed Professor of Discovery in Chemistry at S&T.

Because the polymer substrates are made up of multiple crystals, they have what are called , says Switzer. These grain boundaries can greatly limit the performance of an electronic device.

“Say you’re making a solar cell or an LED,” he says. “In a semiconductor, you have electrons and you have holes, which are the opposite of electrons. They can combine at grain boundaries and give off heat. And then you end up losing the light that you get out of an LED, or the current or voltage that you might get out of a solar cell.”

Most electronics on the market are made of silicon because it’s “relatively cheap, but also highly ordered,” Switzer says.

“99.99 percent of electronics are made out of silicon, and there’s a reason – it works great,” he says. “It’s a single crystal, and the atoms are perfectly aligned. But, when you have a single crystal like that, typically, it’s not flexible.”

By starting with single crystal silicon and growing gold foils on it, Switzer is able to keep the high order of silicon on the foil. But because the foil is gold, it’s also highly durable and flexible.

“We bent it 4,000 times, and basically the resistance didn’t change,” he says.

The gold foils are also essentially transparent because they are so thin. According to Switzer, his team has peeled foils as thin as seven nanometers.

Switzer says the challenge his research team faced was not in growing gold on the single crystal silicon, but getting it to peel off as such a thin layer of foil. Gold typically bonds very well to silicon.

“So we came up with this trick where we could photo-electrochemically oxidize the silicon,” Switzer says. “And the gold just slides off.”

Photoelectrochemical oxidation is the process by which light enables a semiconductor material, in this case silicon, to promote a catalytic oxidation reaction.

Switzer says thousands of gold foils—or foils of any number of other metals—can be made from a single crystal wafer of .

The research team’s discovery can be considered a “happy accident.” Switzer says they were looking for a cheap way to make single crystals when they discovered this process.

“This is something that I think a lot of people who are interested in working with highly ordered materials like single crystals would appreciate making really easily,” he says. “Besides making flexible devices, it’s just going to open up a field for anybody who wants to work with .”

Explore further: ‘Nanospears’ could lead to better solar cells, lasers, lighting

More information: Naveen K. Mahenderkar et al. Epitaxial lift-off of electrodeposited single-crystal gold foils for flexible electronics, Science (2017). DOI: 10.1126/science.aam5830

Read more at: https://phys.org/news/2017-03-gold-foil-discovery-wearable-technology.html#jCp

Read more at: https://phys.org/news/2017-03-gold-foil-discovery-wearable-technology.html#jCp