SGL Group to sell its cathodes business
SGL Group has confirmed the sale of its cathodes, furnace linings, and carbon electrodes business to investment company Triton for €250 million. Closing is expected in the fourth quarter 2017.
Following the closing of the transaction, approximately 30 employees in Germany and 600 employees in Poland, who are based at the two production facilities in Nowy Sacz and Raciborz, will move from SGL Group to their new owner.
The sale will result in a book profit of around €130 million in the current fiscal year of SGL Group.
This story is reprinted from material from SGL, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Renishaw’s first half year report
Renishaw has reported first half year revenue of £240.4 million, an increase of 21% from £198.5 million for the same period of 2016. First half year profit before tax was £35.7 million, compared with restated £28.6 million last year.
Revenue in the Far East grew by 27%, from £85.5 million last year to £108.7 million (18% at constant exchange rates). In Europe, revenue increased by 18%, from £52.1 million to £61.3 million (3% at constant exchange rates), in the Americas, revenue was higher by 11%, from £43.7 million to £48.6 million (6% at constant exchange rates) and in the UK, revenue was up by 20%, from £11.0 million to £13.2 million.
‘Notwithstanding current economic uncertainties, the board remains confident in the future prospects of the group,’ the company said. ‘We continue to anticipate growth in both revenue and profit in this financial year and expect full year revenue to be in the range of £500 million to £530 million and profit before tax to be in the range of £85 million to £105 million.’
This story is reprinted from material from Renishaw, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Bodycote reports almost 19% growth
Automotive specialist Bodycote reports revenues growth of 18.8% to £345.7 million in the first half of 2017, up from £291.0 million in 2016, corresponding to a growth of 8.3% at constant exchange rates.
The group’s headline operating profit grew 25.2% to £61.7 million (2016: £49.3 million). Overall civil aerospace revenues were up 4.4%, led by strong growth in the UK, while defence (predominantly a North American market for the group) was down on the same period last year. Revenues from the energy sector were 4.1% lower, with the oil and gas sector continuing to register a decline compared with the first half of 2016, when oil and gas revenues were still falling. Bodycote achieved revenue growth of 15.5% in the car and light truck sector as new programs, especially using specialist technologies, continue to build. Group revenues in the general industrial sector increased 11.8% in the first half, with growth across all of the group’s key territories.
This story is reprinted from material from Bodycote, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Uncoiled chains lead to heat-dissipating plastics
Advanced plastics could usher in lighter, cheaper, more energy-efficient product components, including those used in vehicles, LEDs and computers – if only the plastics were better at dissipating heat. A new technique that can change plastic's molecular structure to help it cast off heat represents a promising step in that direction.
Developed by a team of material scientists and mechanical engineers at the University of Michigan and detailed in a new paper in Science Advances, the process is inexpensive and scalable, and can likely be adapted to a variety of other plastics. In preliminary tests, it made a polymer about as thermally conductive as glass – still far less than metals or ceramics, but six times better at dissipating heat than the same polymer without the treatment.
"Plastics are replacing metals and ceramics in many places, but they're such poor heat conductors that nobody even considers them for applications that require heat to be dissipated efficiently," said Jinsang Kim, U-M materials science and engineering professor. "We're working to change that by applying thermal engineering to plastics in a way that hasn't been done before."
The process is a major departure from previous approaches, which have focused on adding metallic or ceramic fillers to plastics. This has met with limited success: a large amount of filler must be added, which is expensive and can change the properties of the plastic in undesirable ways. Instead, the new technique uses a process that engineers the structure of the material itself.
Plastics are made of long chains of molecules that are tightly coiled and tangled like a bowl of spaghetti. As heat travels through the material, it must travel along and between these chains – an arduous, roundabout journey that impedes its progress.
The team – which also includes U-M associate professor of mechanical engineering Kevin Pipe, mechanical engineering graduate researcher Chen Li and materials science and engineering graduate student Apoorv Shanker – used a chemical process to expand and straighten the molecular chains, thereby providing the heat energy with a more direct route through the plastic. To accomplish this, they dissolved the plastic in water, then added electrolytes to the solution to raise its pH, making it alkaline.
This caused the individual links in the polymer chain – called monomers – to take on a negative charge, leading them to repel each other. As the monomers move apart, they unfurl the chain's tight coils. Finally, the water and polymer solution is sprayed onto plates using a common industrial process known as spin casting, which reconstitutes the solution into a solid plastic film.
The uncoiled molecular chains now make it easier for heat to travel through the plastic. The team also found that the process has a secondary benefit – it stiffens the polymer chains and helps them pack together more tightly, making them even more thermally conductive.
"Polymer molecules conduct heat by vibrating, and a stiffer molecule chain can vibrate more easily," Shanker said. "Think of a tightly stretched guitar string compared to a loosely coiled piece of twine. The guitar string will vibrate when plucked, the twine won't. Polymer molecule chains behave in a similar way."
Pipe says the work could have important consequences because of the large number of polymer applications in which temperature is important. "Researchers have long studied ways to modify the molecular structure of polymers to engineer their mechanical, optical or electronic properties, but very few studies have examined molecular design approaches to engineer their thermal properties," Pipe said. "While heat flow in materials is often a complex process, even small improvements in the thermal conductivities of polymers can have a large technological impact."
The team is now looking at making composites that combine the new technique with several other heat dissipating strategies to further increase thermal conductivity. They're also working to apply the concept to other types of polymers beyond those used in this research. A commercial product is likely several years away.
"We're looking at using organic solvents to apply this technique to non-water soluble polymers," Li said. "But we believe that the concept of using electrolytes to thermally engineer polymers is a versatile idea that will apply across many other materials."
This story is adapted from material from the University of Michigan, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Chitin and copper combine to ward off bacterial biofilms
By some estimates, bacterial strains resistant to antibiotics – so-called superbugs – will cause more deaths than cancer by 2050. Biomedical and chemistry researchers at Colorado State University are using creative tactics to subvert these superbugs and their mechanisms of invasion. In particular, they're devising new ways to keep harmful bacteria from forming sticky matrices called biofilms – and doing it without antibiotic drugs.
Researchers from the laboratory of Melissa Reynolds, associate professor of chemistry and the School of Biomedical Engineering, have created a new material that inhibits biofilm formation by the virulent superbug Pseudomonas aeruginosa. Their material, described in a paper in Advanced Functional Materials, could form the basis for a new kind of antibacterial surface that prevents infections and reduces reliance on antibiotics.
Bella Neufeld, first author of the paper and a graduate student who led the research, explained that her passion for finding new ways to fight superbugs is motivated by how adaptive and impenetrable they are, especially when they are allowed to form biofilms. "Biofilms are nasty once they form, and incredibly difficult to get rid of," Neufeld said.
Many people picture bacteria and other microorganisms in their friendlier, free-floating state – like plankton swimming in a high school petri dish. But when bacteria are able to attach to a surface and form a biofilm, they become stronger and more resistant to normal drugs.
In a classic example, cystic fibrosis patients are made sick by hordes of P. aeruginosa bacteria forming a sticky film on the endothelial cells of the patients' lungs. Once those bacteria attach, drugs won't kill them. Or a wound can become infected with a bacterial biofilm, making it more difficult for the wound to heal.
Reynolds' research group makes biocompatible devices and materials that resist infection and won't be rejected by the body. In this most recent work, they designed a material with inherent properties that mean it can prevent a bacterial film from forming in the first place.
In the lab, they demonstrated an 85% reduction in P. aeruginosa biofilm adhesion, and conducted extensive studies showing the reusability of their film. This indicated that its antibacterial properties are driven by something inherent to the material, so its efficacy won't fade in a clinical setting.
They used a material they've worked with before for other antimicrobial applications: a copper-based metal-organic framework (MOF) that's stable in water. They embedded this copper MOF within a matrix of chitosan, a material derived from the polysaccharide chitin, which makes up insect wings and shrimp shells. Chitosan is already widely used as a wound dressing and hemostatic agent.
Neufeld says the new biomaterial could highlight new avenues for antibacterial surfaces. For example, the material could be used for a wound dressing made from the chitosan matrix rather than traditional gauze.
This story is adapted from material from Colorado State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Bio-based composites on a larger scale
Researchers from Chemnitz University of Technology in Germany have developed a range of bio-based fiber-plastic-compounds that could be produced on a large scale as an alternative to glass and carbon fiber reinforced plastics.
‘We replace the glass or carbon fiber with natural fibers such as flax,’ said Ahmed-Amine Ouali, research associate at the Institute of Lightweight Structures. ‘Our plastic matrix is a biopolymer of renewable resources. Thus, the carbon footprint in the product’s life cycle is significantly better.’ The use of continuous filaments renders the compound extremely stiff and highly rigid in the direction of the fibers, the researchers say.
The researchers’ main objective was to develop a procedure with which the semi-finished products made from plastics and natural fibers can be produced on large-scale. Film-stacking-technology is currently common practice. In this procedure, single layers (for example plastic-film plus non-crimp-fabric plus plastic-film) are stacked into a heat press, fused under pressure, removed and further processed into plates in another machine. For the continuous procedure the MERGE researcher had to design a new calender. ‘Natural fibers have a special characteristic in contrast to glass or carbon fibers: they readily absorb fluids. Thus, prior to the processing they have to dry,’ said Ouali. ‘At the institute we developed a dryer plant that can be attached to the calender almost without space in between. This way the dried fiber has almost no contact to the moist ambient air.’
The Omega-calender consists of several cylinders through which the flax-fiber- plastic-films can theoretically be led continuously, heated up, and pressed together. After the impregnation process and the cooling of the thermoplastic prepregs the fiber-matrix-semi-finished product is complete. It is wound up on a role and can be further processed in various ways, by cutting to size with numerous layers pressed as a stack a rigid plate emerges. ‘We can also form the semi-finished product once more and combine it with injection molded products,’ said Ouali.
The production procedure is currently intermittent, with a stop after the continuous production of the prepreg-semi-finished product. Depending on the need the production then continues in numerous different plants. Yet, with regard to large-scale production, the manufacturing path can be supplemented or combined accordingly, the researchers say.
‘We will further experiment with various fiber structures as knitted or non-crimp fabrics, or in other forms and with different matrix combinations for example films or spun-bonded fabric,’ said Ouali.
This story is reprinted from material from Chemnitz University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Evonik ‘on target’ after the first half of 2017
Chemicals company Evonik says that sales grew to €7.3 billion in the first six months of 2017, a rise of 15% compared with the first half of 2016.
The company said that this was partly due to the first-time consolidation of the specialty additives business of the US company Air Products as well as a rise in demand and slightly higher selling prices.
Adjusted net income increased 10% to €549 million, while adjusted earnings per share improved to €1.18. Net income fell 3% to €394 million, principally as a result of one-time expenses in connection with the acquisition of the Air Products business. Performance Materials sales grew 18% to €1.89 billion in the first six months, and adjusted EBITDA almost doubled to €328 million.
Evonik confirmed its forecast to increase both sales and operating profit for the full year 2017 and said that adjusted EBITDA is still expected to grow to between €2.2 billion and €2.4 billion (2016: €2.165 billion).
Our business development is on target,’ said Christian Kullmann, chairman of the executive board. ‘Moreover, we are reaping the first benefits of the biggest acquisition in our history.’
This story is reprinted from material from Evonik, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
voestalpine reports 2% revenue increase
voestalpine reports a yearly increase in revenue by 2.0%, from €11.1 billion to €11.3 billion, despite ‘an economic environment influenced more than usual by political events including the Brexit referendum in the UK, the US presidential election, terror and war in the Middle East, the challenges of immigration in Europe, and the global rise in trade barriers,’ the company said.
Aside from generally strong demand in the steel sector, it was the automotive, aerospace, and consumer goods customer segments in particular which posted high order levels, the company said.
‘We expect a strong, significantly higher revenue and earnings performance for the first half of the year compared to the same period in the previous year,’ said Wolfgang Eder, chairman of the management board. ‘However, it will only be possible to evaluate the economic situation for the second half of the business year with more precision after the summer ahead.
‘Over the course of 2017/18, a whole series of recent major investments made by the voestalpine Group, such as the direct reduction plant in Texas, the new wire mill in Leoben, Donawitz, in Austria, and several downstream investments in Europe, the USA, and China, will be reflected in revenue and earnings for the first time. […] Against this backdrop, despite the uncertainties inherent in assessing the second half of the business year 2017/18, from our current perspective we expect a clearly positive revenue and earnings performance.’
This story is reprinted from material from voestalpine, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
ExOne 3D prints steel necklace
Additive manufacturing (AM) company ExOne, has produced a fully 3D printed, interlocking designer steel necklaces of its kind for the LACE by Jenny Wu jewelry line.
The necklace was 3D printed in steel using ExOne’s binder jetting technology, an AM process in which a liquid binding agent is selectively deposited to join powder particles.
‘Unlike most 3D printed necklaces out there, our pieces are fully 3D printed without any additional analog assembly nor non-3D printed hardware to hold these incredible statement pieces around the neck,’ said Jenny Wu, director of LACE. ‘This type of necklace was a technical and financial challenge to 3D print entirely in metal until now. While we love the wearability of our nylon necklaces, our goal was always to 3D print our necklaces in metal, from the hinge down to the latch. After many years of testing and prototyping with various different technologies, we were finally able to produce the Catena necklace with ExOne and their 3D printing process.’
This story is reprinted from material from ExOne, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Polymer bonds with 2D material under pressure to store energy
Scientists at Penn State have shown experimentally that a new, lightweight composite material for energy storage in flexible electronics, electric vehicles and aerospace applications can store energy at operating temperatures well above current commercial polymers. This composite of a polymer and a two-dimensional (2D) material can be produced with techniques already used by industry.
"This is part of a series of work we have done in our lab on high-temperature dielectrics for use in capacitors," explained Qing Wang, professor of materials science and engineering at Penn State. "Prior to this work, we had developed a composite of boron nitride nanosheets and dielectric polymers, but realized there were significant problems with scaling that material up economically."
Scalability – or making advanced materials in commercially relevant amounts for devices – has been the defining challenge for many of the new, 2D materials being developed in academic labs. "From a soft materials perspective, 2D materials are fascinating, but how to mass produce them is a question," Wang said. "Plus, being able to combine them with polymeric materials is a key feature for future flexible electronics applications and electronic devices."
To solve this problem, Wang's lab collaborated with a group at Penn State working with 2D crystals. "This work was conceived in conversations between my graduate student, Amin Azizi, and Dr. Wang's graduate student, Matthew Gadinski," said Nasim Alem, assistant professor of materials science and engineering and a faculty member in Penn State's Center for 2-Dimensional and Layered Materials. "This is the first robust experiment in which a soft polymeric material and a hard 2D crystalline material have come together to create a functional dielectric device."
Azizi, now a post-doctoral fellow at the University of California, Berkeley, and Gadinski, now a senior engineer at Dow Chemical, developed a technique using chemical vapor deposition to make multilayer, hexagonal boron-nitride nanocrystal films and transfer the films to both sides of a polyetherimide (PEI) film. They then used pressure to bond the films together into a three-layer sandwich structure. In a result that surprised the researchers, pressure alone, without any chemical bonding, was enough to produce a free-standing film strong enough to potentially be manufactured in a high-throughput roll-to-roll process. The researchers report their results in a paper in Advanced Materials.
Hexagonal boron nitride is a wide band-gap material with high mechanical strength. Its wide band gap makes it a good insulator and protects the PEI film from dielectric breakdown at high temperatures, the reason for failure in other polymer capacitors. At operating temperatures above 176°F, the current best commercial polymers start to lose efficiency, but hexagonal-boron-nitride-coated PEI can operate at high efficiency at over 392°F. Even at these high temperatures, the coated PEI remained stable for over 55,000 charge-discharge cycles in testing.
"Theoretically, all these high-performance polymers that are so commercially valuable can be coated with boron nanosheets to block charge injection," Wang said. "I think this will make this technology feasible for future commercialization."
"There are many devices made with 2D crystals at the laboratory scale, but defects make them a problem for manufacturing," added Alem. "With a large band-gap material like boron nitride, it does a good job despite small microstructural features that might not be ideal."
First-principles calculations determined that the electron barrier, which is established at the interface between the PEI/hexagonal boron-nitride structure and the metal electrodes applied to the structure to deliver current, is significantly higher than typical metal electrode-dielectric polymer contacts. This makes it more difficult for charges from the electrode to be injected into the film.
This story is adapted from material from Penn State, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
New research shows graphene can grow on trees
Scientists at Rice University have made wood into an electrical conductor by turning its surface into graphene. Rice chemist James Tour and his colleagues used a laser to blacken a thin film pattern onto a block of pine; this pattern is made from laser-induced graphene (LIG), a form of the atom-thin carbon material that was discovered at Rice in 2014.
"It's a union of the archaic with the newest nanomaterial into a single composite structure," Tour said. He and his colleagues report this discovery in a paper in Advanced Materials.
Previous iterations of LIG were made by heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser. Whereas conventional graphene comprises a flat sheet of hexagonal carbon atoms, LIG is a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.
In the same way that not just any polyimide would produce LIG, some woods are preferred over others, Tour said. The research team, led by Rice graduate students Ruquan Ye and Yieu Chyan, tried birch and oak, but found that pine's cross-linked lignocellulose structure made it better at producing high-quality graphene than woods with a lower lignin content. Lignin is the complex organic polymer that forms rigid cell walls in wood.
Ye said that turning wood into graphene opens new avenues for the synthesis of LIG from non-polyimide materials. "For some applications, such as three-dimensional graphene printing, polyimide may not be an ideal substrate," he said. "In addition, wood is abundant and renewable."
As with polyimide, the process takes place with a standard industrial laser at room temperature and pressure, and in an inert argon or hydrogen atmosphere. Without oxygen, heat from the laser doesn't burn the pine but instead transforms the surface into wrinkled flakes of graphene foam bound to the wood surface. Changing the laser power also changed the chemical composition and thermal stability of the resulting LIG. At 70% power, the laser produced the highest quality of what the scientists dubbed ‘P-LIG’, where the P stands for ‘pine’.
The scientists took their discovery a step further by turning P-LIG into electrodes for splitting water into hydrogen and oxygen and supercapacitors for energy storage. For the former, they deposited layers of cobalt and phosphorus or nickel and iron onto P-LIG to make a pair of electrocatalysts with high surface areas that proved to be durable and effective. Depositing polyaniline onto P-LIG turned it into an energy-storing supercapacitor that had usable performance metrics.
"There are more applications to explore," said Ye. "For example, we could use P-LIG in the integration of solar energy for photosynthesis. We believe this discovery will inspire scientists to think about how we could engineer the natural resources that surround us into better-functioning materials."
Tour sees a more immediate environmental benefit from biodegradable electronics. "Graphene is a thin sheet of a naturally occurring mineral, graphite, so we would be sending it back to the ground from which it came along with the wood platform instead of to a landfill full of electronics parts."
This story is adapted from material from Rice University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Nowoven presentations now available
The Presentations from NHPA2017, the Conference on Nonwovens for High-performance Applications 2017, are now available to download or order on CD-Rom.
The conference took place from 7-8 March 2017 in Prague, Czech Republic. Key Topics included nonwoven-based composite reinforcements with optimized structures, nonwoven textiles made with recycled carbon fibers for automotive applications, glass and carbon fiber mats, nonwoven textiles made with recycled carbon fibers as well as a keynote speech describing how Europe's booming composites markets could create new opportunities for fiber-based reinforcements.
For more information go here.
This story is reprinted from material from Research and Markets, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Superior Graphite celebrates 100 years
Graphite processor Superior Graphite is commemorating 100 years of manufacturing graphite and carbon-based solutions for its global customer base. The company has recently announced improved infrastructure investments, new executive appointments, and new software/business analytics to support future growth.
‘Superior Graphite is more than a manufacturer; for 100 years, our customers have trusted us to help them solve problems and conquer new markets with our expert knowledge of graphite solutions,’ claimed Edward O. Carney, president and CEO. ‘As we look ahead to the second century, our partners can feel confident we will continue to apply our deep knowledge of graphite technology to provide more efficiencies, innovation and collaboration.’
The Chicago-based company was found in 1917 as the Superior Flake Graphite Company. In 1925, the company opened its bulk graphite plant in the clearing industrial district of Chicago and in 1977, Superior Graphite opened its first electro-thermal treatment/purification facility in Hopkinsville, Kentucky and later a second such facility in Sundsvall, Sweden in 1994. Its Advanced Materials facility was opened in 1993 in Hopkinsville, Kentucky to add synthesis of beta and processing of alpha silicon carbide to the company’s portfolio.
This story is reprinted from material from Superior Graphite, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
SAE announces transmission and driveline event speakers
SAE International has announced the keynote speaker and executive panel for the Transmission and Driveline Symposium, which takes place from 14-15 November in Dearborn, Michigan, USA.
On 14 November, Prof Dr Peter Johannes Tenberge who serves as the Chair of Industrial and Automotive Drivetrains at Ruhr-University Bochum in Germany will speak on electrification, with an emphasis and specific detailed example on FWD parallel hybrid constructions and in specific global regions.
The Transmission and Driveline Symposium will host a number of additional technical sessions about autonomous driving’s impact on transmission and driveline design, electrification, controls and simulation, high performance lightweighting applications and launch devices.
For more information about Transmission and Driveline Symposium, the technical program, or to register for the event, please visit www.sae.org/transmission.
This story is reprinted from material from SAE, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Collective rattling blocks heat transfer in crystalline semiconductor
A newly discovered collective rattling effect in a type of crystalline semiconductor blocks most heat transfer while preserving high electrical conductivity – a rare pairing that scientists say could reduce heat build-up in electronic devices and turbine engines, among other possible applications.
A team led by scientists at the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) discovered these exotic traits in a class of materials known as halide perovskites, which are considered promising candidates for next-generation solar panels, nanoscale lasers, electronic cooling and electronic displays.
These interrelated thermal and electrical (or ‘thermoelectric’) properties were found in nanoscale wires of cesium tin iodide (CsSnI3). The material was observed to have one of the lowest levels of heat conductivity among materials with a continuous crystalline structure. This so-called single-crystal material can also be more easily produced in large quantities than typical thermoelectric materials, such as silicon-germanium, the researchers said.
"Its properties originate from the crystal structure itself. It's an atomic sort of phenomenon," said Woochul Lee, a postdoctoral researcher at Berkeley Lab who was the lead author of a paper on this work in the Proceedings of the National Academy of Sciences. These are the first published results relating to the thermoelectric performance of this single-crystal material.
Researchers earlier thought that the material's thermal properties were the product of ‘caged’ atoms rattling around within the material's crystalline structure, as had been observed in some other materials. Such rattling can serve to disrupt heat transfer in a material.
"We initially thought it was atoms of cesium, a heavy element, moving around in the material," said Peidong Yang, a senior faculty scientist at Berkeley Lab's Materials Sciences Division who led the study.
Jeffrey Grossman, a researcher at the Massachusetts Institute of Technology, then performed some theory work and computerized simulations that helped to explain what the team had observed. Researchers also used Berkeley Lab's Molecular Foundry, which specializes in nanoscale research, in the study.
"We believe there is essentially a rattling mechanism, not just with the cesium. It's the overall structure that's rattling; it's a collective rattling," Yang said. "The rattling mechanism is associated with the crystal structure itself," and is not the product of a collection of tiny crystal cages. "It is group atomic motion," he added.
Within the material's crystal structure, the distance between atoms is shrinking and growing in a collective way that prevents heat from easily flowing through. But because the material is composed of an orderly, single-crystal structure, electrical current can still flow through it despite this collective rattling. Its electrical conductivity is like a submarine traveling smoothly in calm underwater currents, while its thermal conductivity is like a sailboat tossed about in heavy seas at the surface.
According to Yang, two major applications for thermoelectric materials are in cooling, and in converting heat into electrical current. For this particular cesium tin iodide material, cooling applications –such as a coating to help cool electronic camera sensors – may be easier to achieve than heat-to-electrical conversion, he said.
A challenge is that the material is highly reactive to air and water, so it requires a protective coating or encapsulation to function in a device.
Cesium tin iodide was first discovered as a semiconductor material decades ago, but only in recent years has it been rediscovered for its other unique traits, Yang said. "It turns out to be an amazing gold mine of physical properties," he noted.
To measure the thermal conductivity of the material, researchers bridged two islands of an anchoring material with a cesium tin iodide nanowire. The nanowire was connected at either end to micro-islands that functioned as both a heater and a thermometer. Researchers heated one of the islands and precisely measured how the nanowire transported heat to the other island.
They also performed scanning electron microscopy to precisely measure the dimensions of the nanowire. They used these dimensions to provide an exacting measure of the material's thermal conductivity. The team repeated the experiment with several different nanowire materials and multiple nanowire samples to compare thermoelectric properties and verify the thermal conductivity measurements.
"A next step is to alloy this (cesium tin iodide) material," Lee said. "This may improve the thermoelectric properties."
Also, just as computer chip manufacturers implant a succession of elements into silicon wafers to improve their electronic properties – a process known as ‘doping’ – scientists hope to use similar techniques to more fully exploit the thermoelectric traits of this semiconductor material. This is relatively unexplored territory for this class of materials, Yang said.
This story is adapted from material from the Lawrence Berkeley National Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Crystal gels form like ice crystals in clouds
Scientists at the University of Bristol in the UK have, for the first time, observed the formation of a crystal gel with particle-level resolution, allowing them to study the conditions by which these new materials form. The study showed that the mechanism of crystal growth follows the same strategies by which ice crystals grow in clouds, an analogy that could improve our understanding of these fundamental processes.
In addition, the novel mechanism allowed the research team to spontaneously form sponge-like nanoporous crystals in a continuous process. Nanoporous crystals of metals and semiconductors can be obtained without dealloying, which can be important for catalytic, optical, sensing and filtration applications.
The work is a collaboration between the University of Tokyo in Japan (where the experiments were conducted), the University of Bristol and the Institute Lumiere Matiere in Lyon, France. The findings are published in a paper in Nature Materials.
"In particular we observed some new formation mechanisms," said John Russo at the University of Bristol's School of Mathematics and co-author of the paper. "We discovered that in order to obtain these crystal-gel structures, the original gel structure has to undergo a structural reorganization, in which bonds between colloidal particles are broken to release the internal stress that was accumulated during the rapid growth of the gel – a process called stress-driven aging.
"After this, we observed that the way the branches of the gel crystallize is reminiscent of the process by which water droplets crystallize in clouds. We were then able to observe processes that promote crystallization through an intermediate gas phase. This is the first time these fundamental processes are observed at a particle-level resolution, which gives us unprecedented insight over how the process occurs."
The paper reports the results of experiments on an out-of-equilibrium phase of matter obtained by mixing micrometer-size colloidal particles with short polymer chains in a good solvent. The role of the polymers is to induce an effective attraction between the colloidal particles, due to a physical effect called depletion, whose origin is purely entropic.
At the beginning of the experiment, colloidal particles repel each other due to electrostatic repulsion. In order to induce depletion attraction between the colloid particles, the sample is put in contact with a salt solution through a semi-permeable membrane. As the salt diffuses through the semi-permeable membrane, it screens the electrostatic repulsion between the colloidal particles, which then start to aggregate.
The whole process of aggregation is observed with a confocal microscope, which takes fast scans of the sample at different heights. This allows the researchers to reconstruct the coordinates of the colloidal particles with image analysis, and study how these particles move over the course of several hours.
If the polymer concentration is high, the system will form a gel – a disordered state in which colloidal particles aggregate to form interconnected branches that span the whole system, and that give rigidity to the structure.
"What we have demonstrated, instead, is that if we tune the polymer concentration at right value (next to what is called a critical point), the system will form a different type of gel, in which the colloidal particles crystallize throughout the gel structure, giving origin to a porous material made of crystalline branches," explained Russo.
This story is adapted from material from the University of Bristol, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Current Opinion in Biomedical Engineering publishes 1st volume
The first volume of the brand new review journal Current Opinion in Biomedical Engineering is now available for you to read and download online via ScienceDirect.
Current Opinion in Biomedical Engineering provides systematic and focused reviews of the latest developments in different areas of biomedical engineering including: biomaterials; biomechanics and mechanobiology; biomedical imaging; molecular and cellular engineering; neural engineering; tissue engineering and regenerative medicine; and novel biomedical technologies.
The first volume is themed 'The Future of Biomedical Engineering' and is edited by the Journal’s Editor-in-Chief, George A. Truskey, Duke University, USA. “For the inaugural issue, we focus upon a few key topics that represent emerging research opportunities in biomedical engineering.” says Truskey, “Many are at an early stage and only key issues are being identified. They all have the potential to enhance our understanding on complex biological functions and could lead to novel therapies.”
Read the first volume, including the full editorial, online for free until December 31, 2017.
Journal of Immunology and Regenerative Medicine is now open for submissions
The Journal of Immunology and Regenerative Medicine is a brand new peer-reviewed journal aiming to explore the potential and essential roles of the immune system in tissue and organ development, maintenance, response to environmental stressors, response to injury, and in the processes of tissue repair and regeneration.
The journal’s expert editorial team is headed by Editor-in-Chief, Stephen F. Badylak at University of Pittsburgh, USA, and Deputy Editor, Thomas Wynn at the National Institutes of Health, USA.
“This new journal provides a forum for publication of original research papers, reviews, short communications, and editorials directed at the interface of the fields of Immunology and Regenerative Medicine.”, say the editors. “We have assembled a distinguished expert group of Associate Editors and Editorial Board Members who will assure a timely review of all manuscripts and maintain the highest standards of quality and scientific rigor, while providing equal opportunity for the publication of studies originating in either community.”
Visit the Journal of Immunology and Regenerative Medicine homepage to read the full Guide for Authors and submit your paper online.
Here are five reasons why the Journal of Immunology and Regenerative Medicine is the perfect platform for your research:
Rapid online publication
The Journal of Immunology and Regenerative Medicine uses an Article-Based Publishing system in which your article will receive full volume and page citation details upon proof correction, so your work can be cited straight away.
No submission or page fees
We will not charge you for submitting your research to the Journal and we do not impose word limits or page fees. If you would like to publish your research on an open access basis, you can find out more here.
You can publish illustrations and figures in color for free
As an online-only journal, all images and figures will be published in full color, free of charge.
Enrich your research with 3D viewers and Virtual Microscope
Authors are encouraged to take advantage of Elsevier’s article enrichment tools including: protein and 3D radiological/neuroimaging viewers, antibody database linking, and the Virtual Microscope. Find out more about the available tools here.
Share your research
You will be emailed a ShareLink once the final version of your article is published online. This special link offers 50 days of free online access to your article for you to share with your colleagues and on your social media networks.
SSRN launches ChemRN - a working paper repository and preprint server
The launch of ChemRN follows hot on the heels of the BioRN launch in June 2017, SSRN’s new network dedicated to biology and its first outside the social sciences. BioRN already has nearly 5,000 papers live from approximately 6,500 authors.
Gregg Gordon, Managing Director of SSRN, said: “The launch of ChemRN is part of our strategy to extend the expertise and knowledge we have in building community driven networks to benefit even more people in the research community. It’s been a little over a month since we launched BioRN, our network dedicated to biology research. It has been a huge success and we look forward to ChemRN being just as a popular.”
Researchers can share ideas and other early stage research, including posting preprints and working papers on ChemRN. Users can quickly upload and read papers for free, across Chemistry, including the fields of Energy, Environmental and Materials Sciences. Join Gregg’s live webcast on August 17.
Researchers can post preprints and working papers on ChemRN, share ideas and other early stage research, and collaborate. It allows users to quickly upload and read abstracts and full text papers, free of charge.
A preprint is the author’s own write-up of research results and analysis that has not been peer-reviewed, nor had any value added to it by a publisher (such as formatting, copy-editing, technical enhancements). A preprint server, or working paper repository as they are also known, allows users to share these documents.
SSRN has been serving the research community since 1994 and was acquired by Elsevier in May 2016. Since joining Elsevier, SSRN has completely redesigned its website making it cleaner and easier to use. It has also launched full-text search. SSRN is now working towards deeper integration with Elsevier’s other research products, particularly Mendeley’s reference management software and Pure’s research management system.
Read more on Elsevier Connect.