Applied Graphene Materials (AGM), which makes graphene materials, has worked with plastic composite manufacturers to help develop a supercar tailgate.
The company worked with Magna Exteriors and prepreg specialist SHD Composites to develop the W Motors Fenyr SuperSport tailgate using AGM’s graphene-improved epoxy prepreg. This development follows the launch of a range of AGM graphene-improved prepreg materials by SHD in March 2017, with SHD subsequently developing the MTC9810 epoxy prepreg system.
According to the companies, the prepreg offers increased torsional stiffness, interlaminar shear strength and laminate fracture toughness, in addition to improved surface finish, in-service fatigue life and improved properties under hot and wet conditioning.
‘We are confident that AGM’s graphene can deliver significant benefits to the composites sector and we are pleased to be making progress towards application in a number of end industries through our valuable collaborations with industry partners such as SHD and Magna,’ said Jon Mabbitt, CEO of AGM.
This story uses material from AGM,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Valve maker Aidro Hydraulics and Fraunhofer Institute have won the Additive World Design award at the Additive Manufacturing Challenge run by 3D printing company Additive Industries.
The awards were for redesigns of very common industrial parts where the impact of the design for additive manufacturing would be substantial and the companies winning design was for a generic hydraulic manifold for a street cleaning vehicle. The redesign has two parts, is smaller than previous versions, and reportedly has improved flow due to improved, curved channels. The problem of leakage caused by auxiliary plug failure is eliminated and the weight can be reduced by 70%.
The student prize went to Yogeshkumar Katrodiya, an Indian student completing his masters at the Fraunhofer Institute. Yogeshkumar designed an integrated shaft and gear with internal channels transporting lubricant to the gears for cooling. The helix shaped cooling channels were applied to increase the cooling capacity and the whole piece had a weight reduction of 50%.
This story uses material from Fraunhofer,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Lanxess says that it has now extended the use of its plastic/metal hybrid technology to make hollow profiles with round or rectangular cross sections.
This hybrid technology makes use of glass fiber reinforced polyamide 6 for injection molding as well as a steel or aluminum sheet as metal component.
‘Compared to sheet metal, hollow profiles show significantly higher dimensional stability as well as increased torsional strength and stiffness,’ said Lukas Schröer, project manager for lightweight structures. ‘We believe that this new hollow profile hybrid technology enables the manufacturing of components such as cross car beams, which up until now were not resilient enough using classic plastic metal hybrid technology.’
Lanxess developed a one-step process to make the part where the metal inserts can be automatically placed into the injection molding tool. Due to their production process, these metal inserts exhibit dimensional tolerances, which can damage the tool. In case of undersized inserts leaks in the tool system may result and to avoid the profile collapsing due to the high levels of melt pressure during the injection molding process, the metal insert has to be supported. Another challenge for the company was to create a long-lasting, form fitting bond between the plastic and the metal in all directions.
The company says that the technology could be used to make seat structures, front ends, tail gates, and mirror brackets in truck as well as furniture, ladders and strollers. It is currently working on expanding hybrid technology to make die-cast or extrusion molding inserts.’
This story uses material from Lanxess,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The MPIF reports that judging for the 2018 Powder Metallurgy (PM) Design Excellence Awards was recently completed at its headquarters. Every year since 1965, MPIF has sponsored the PM Design Excellence Awards, an awards competition in which parts fabricators from among MPIF’s member companies are invited to submit components that epitomize the possibilities inherent in powder metallurgy forming processes.
This year’s 2018 competition had a selection of 46 PM components from 12 companies representing seven market categories. Winners will be announced during the PM Design Excellence Awards Luncheon at POWDERMET2018, taking place from 17–20 June, 2018, San Antonio, Texas.
This story uses material from the MPIF,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The programs for POWDERMET2018: International Conference on Powder Metallurgy & Particulate Materials and AMPM2018, Additive Manufacturing with Powder Metallurgy, have been published online. The conferences will be held in San Antonio, Texas, USA 17–20 June 2018.
The conferences will include extended exhibit hall hours, student poster sessions that allow students to present their work, and a networking event held in the open exhibit hall for extended exhibitor networking.
AMPM2018 registrants will also have access to the POWDERMET2018 conference and digital post-conference proceedings.
Additive Industries reports that it is expanding its operations for industrial 3D metal printing equipment and software development to the United Kingdom and Ireland.
This follows implementation of its systems in Europe and the US in companies such as Airbus, Alfa Romeo Sauber F1 team and GKN.
The company will establish a new center run by Dr Mark Beard, who has over 14 years of experience in the additive manufacturing (AM) industry and was previously technical director at 3TRPD, a UK provider of metal AM and 3D printing. The UK facility will house the company’s MetalFAB1 3D printing machines as well as support process and application development for the UK and Ireland.
This story uses material from Additive Industries,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Lithium-ion batteries are widely used in home electronics and are now being used to power electric vehicles and store energy for the power grid. But their limited number of recharge cycles and tendency to degrade in capacity over their lifetime have spurred a great deal of research into improving the technology.
An international team led by researchers from the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) has now used advanced electron microscopy techniques to show how the ratio of materials that make up a lithium-ion battery electrode affects its structure at the atomic level. They’ve also used the same techniques to show how the surface of the electrode is very different from the interior of the material. They report their findings in a paper in Energy & Environmental Science.
Knowing how the internal and surface structure of a battery material changes over a wide range of chemical compositions will aid future studies on cathode transformations and could also lead to the development of new battery materials.
"This finding could change the way we look at phase transformations within the cathode and the resulting loss of capacity in this class of material," said Alpesh Khushalchand Shukla, a scientist at Berkeley Lab's Molecular Foundry, and lead author of the paper. "Our work shows that it is extremely important to completely characterize a new material in its pristine state, as well as after cycling, in order to avoid misinterpretations."
In previous work, researchers at the Molecular Foundry, a research center specializing in nanoscale science, revealed the structure of cathode materials containing ‘excess’ lithium, resolving a longstanding debate.
Now, the research team has used a suite of electron microscopes both at the National Center for Electron Microscopy (NCEM), a Molecular Foundry facility, and at SuperSTEM, the National Research Facility for Advanced Electron Microscopy in Daresbury, UK. This revealed that while the atoms throughout the interior of the cathode material remained in the same structural pattern across all compositions, decreasing the amount of lithium caused an increase in randomness in the position of certain atoms within the structure.
By comparing different compositions of cathode material with battery performance, the researchers also demonstrated it was possible to optimize battery performance in relation to capacity by using a lower ratio of lithium to other metals.
The most surprising finding was that the surface structure of an unused cathode is very different from the interior of the cathode. In all of their experiments, the researchers found that a thin layer of material on the surface possessed a different structure, known as the ‘spinel’ phase. Several previous studies had overlooked the possibility that this layer might be present on both new and used cathodes.
By systematically varying the ratio of lithium to a transition metal, like trying different amounts of ingredients in a new cookie recipe, the research team was able to study the relationship between the surface and interior structure, and to measure the electrochemical performance of the material. The team took images of each batch of the cathode materials from multiple angles and created complete, three-dimensional (3D) renderings of each structure.
"Obtaining such precise, atomic-level information over length scales relevant to battery technologies was a challenge," said Quentin Ramasse, director of the SuperSTEM Laboratory. "This is a perfect example of why the multiple imaging and spectroscopy techniques available in electron microscopy make it such an indispensable and versatile tool in renewable energy research."
The researchers also used a newly developed technique called 4D scanning transmission electron microscopy (4D-STEM). In transmission electron microscopy (TEM), images are formed after electrons pass through a thin sample. In conventional STEM, the electron beam is focused down to a very small spot (as small as 0.5nm in diameter), which is then scanned back and forth over the sample like a mower on a lawn.
The detector in conventional STEM simply counts how many electrons are scattered (or not scattered) in each pixel. However, in 4D-STEM, the researchers use a high-speed electron detector to record where each electron scatters, from each scanned point. It allows researchers to measure the local structure of their sample at high resolution over a large field of view.
"The introduction of high-speed electron cameras allows us to extract atomic-scale information from very large sample dimensions," said Colin Ophus, a research scientist at NCEM. "4D-STEM experiments mean we no longer need to make a trade-off between the smallest features we can resolve and the field-of-view that we are observing – we can analyze the atomic structure of the entire particle at once."
Joining different kinds of materials together can lead to all kinds of breakthroughs. It's an essential skill that allowed humans to make everything from skyscrapers (by reinforcing concrete with steel) to solar cells (by layering materials to herd electrons).
In electronics, joining different materials together produces heterojunctions, which are fundamental components in solar cells, LEDs and computer chips. The smoother the seam between the two materials, the more easily electrons flow across it, making them essential for determining how well the electronic devices function. What make this tricky is that the two materials are crystals, rigid lattices of atoms that may have very different spacings and don't take kindly to being mashed together.
In a paper in Science, scientists at the University of Chicago and Cornell University report a new technique for ‘sewing’ two patches of crystals seamlessly together at the atomic level to create atomically-thin fabrics.
The team wanted to do this by stitching together different fabric-like, three-atom-thick crystals. "Usually, these are grown in stages under very different conditions: grow one material first, stop the growth, change the condition and start it again to grow another material," explained Jiwoong Park, professor of chemistry in the James Franck Institute and the Institute for Molecular Engineering at the University of Chicago and a lead author of the paper.
Instead, the scientists developed a new process for finding the perfect window that would work for both materials in a constant environment, so they could grow the entire crystal in a single session. According to Park, the resulting single-layer materials are the most perfectly aligned ever grown. The gentler transition meant that, at the points where the two lattices meet, one lattice stretches or grows to meet the other, instead of leaving holes or other defects. The atomic seams are so tight, in fact, that when the scientists looked up close with scanning electron microscopes, they saw that the larger of the two materials puckers a little around the joint.
They decided to test the performance of this heterojunction in one of the most widely used electronic devices: a diode. When two different materials are joined, the electrons are supposed to be able to flow one way through the ‘fabric’, but not the other.
The diode lit up. "It was exciting to see these three-atom-thick LEDs glowing. We saw excellent performance – the best known for these types of materials," said Saien Xie, a graduate student and first author of the paper.
This discovery opens up some interesting ideas for electronics. Devices like LEDs are currently stacked in layers and are usually on a rigid surface. But Park said the new technique could open up new configurations, like flexible LEDs or atom-thick 2D circuits that work both horizontally and laterally.
He also noted that the stretching and compressing changed the optical properties of the crystals due to quantum mechanical effects. This suggests potential for using these heterojunctions as light sensors and LEDs that could be tuned to different colors, for example, or strain-sensing fabrics that change color as they're stretched.
"This is so unknown that we don't even know all the possibilities it holds yet," Park said. "Even two years ago it would have been unimaginable."
This story is adapted from material from the University of Chicago, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
ASTM International’s committee on nonferrous metals and alloys (B02) is inviting experts in the specialty alloys and thermostat metals industry to join in the revision of two ASTM International thermostat standards. The standards were developed by ASTM International’s committee on nonferrous metals and alloys.
On standard covers the specification for thermostat component alloys and describes the requirements for alloys that are used as components in the manufacture of bonded multi-component thermostat metal strip.
The next meeting of ASTM International committee on nonferrous metals and alloys is 21-23 May in San Diego, California, USA.
This story uses material from ASTM,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
More information about ceramics and powder metallurgy show ceramitec has been released.
The show will take place in Munich, Germany, from 10 to 13 April and will start with a joint opening event of ceramitec and the 93rd Annual Meeting of the German Ceramics Society which is taking place on the exhibition grounds in parallel with ceramitec. This will be followed by a panel discussion and a keynote speech from Prof Alexander Michaelis, chair of the Inorganic Non-Metallic Materials Chair of the Technical University of Dresden & Director of the Fraunhofer Institute for Ceramic Technologies and Systems, on the potentials of ceramics for industrial innovation.
The Powder Metallurgy Day will also take place on 10 April followed by the Heavy Clay Day on 11 April and the Technical Ceramics Day on 12 April.
The show will also feature for the first time a special area on additive manufacturing including information on new products and a presentation of innovative exhibits.
This story uses material from ceramitec, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
SGL and partners have won the JEC Innovation Award in the Aerospace Process category for the ‘MAI Sandwich’ project, which involves using composite materials in a sandwich structure in which a light core is combined with ‘skins’ of fiber reinforced plastic on both sides.
The project was run by the Technical University of Munich with partners Airbus, BASF SE, BMW, SGL Group, Foldcore, Neenah Gessner, Neue Materialien Bayreuth and Hofmann.
Currently, producing sandwich structures takes time, making it expensive, the partners says. In traditional processes, producing a standard generic component could take a cycle time of up to one day. This project has revealed that these long cycle times can be reduced drastically to five minutes for a comparable component in the aerospace industry and to 2.5 minutes for a similar component in the automotive sector due to improved integration of the different components, including fusion bonded thermoplastic materials between the core and skins. The companies have also developed a production sequence using the three techniques of thermoforming, injection molding and fusion bonding in a primarily automated working facility.
Components with a sandwich structure are suitable for secondary structures such as floor paneling or interior lining of aircraft or underbody or seat back panels in automobiles.
This story uses material from SGL,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Nowe laboratorium dydaktyczno-badawcze otwarto na Wydziale Inżynierii Środowiska Politechniki Wrocławskiej. Pracownia będzie wykorzystywana m.in. do prowadzenia zajęć z zakresu ogrzewnictwa i ciepłownictwa
André Taylor of New York University and his colleagues there and at Yale University, Northwestern University, and the University of Electronic Science and Technology of China, have developed a new way to make "organic" solar cells more efficient by side-stepping the use of fullerenes and making a solar sandwich instead. [Y Zheng et al Mater Today (2018); 10.1016/j.mattod.2017.10.003]
The conventional organic solar cell structure is a sandwich with an active layer comprising electron donors and acceptors as the filling. It is the filling that absorbs the light energy that drives the processes that allow an electric current to be drawn by the positive and negative electrodes, the two slices of "bread" of the sandwich. Taylor and his colleagues wanted to extend the spectral range of absorption by the filling but without compromising how well the sandwich fits together. "My group works on key parts of the sandwich, such as the electron and hole transporting layers of the bread, while other groups may work only on the interlayer materials. The question is: How do you get them to play together? The right blend of these disparate materials is extremely difficult to achieve."
The team has turned to a squaraine molecule as a crystallizing agent that is also an electron donor to enhance the absorption of the active layer. "By adding this small molecule, it facilitates the orientation of the donor-acceptor polymer (called PBDB-T) with the non-fullerene acceptor, ITIC, in a favorable arrangement," explains Taylor. PBDB-T is poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))]). ITIC is 3,9-bis(2-methylene(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b'] dithiophene).
With this architecture in hand, the team also added another design feature of their own, FRET, or Förster resonance energy transfer. FRET was first observed in photosynthesis so it is apt that science is using the mechanism in solar cells. The team has now achieved 10% efficiency, which was considered an unreachable level just a few years ago. "There are now newer polymer non-fullerene systems that can perform above 13 percent, so we view our contribution as a viable strategy for improving these systems," Taylor says. Lead author on the study and a former student of Taylor, Yifan Zheng suggests that, "We expect that this crystallizing-agent method will attract attention from chemists and materials scientists affiliated with organic electronics. The next step will be to optimise the approach still further.
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".
A uranium-containing mineral known as ewingite, originally found in a damp mine wall in the Czech Republic, has been shown to have a structure with a complexity almost twice that of any previously known mineral. The mineral and its structure were reported by scientists in the USA [T A Olds et al Geol; DOI: 10.1130/G39433.1]
The complexity of a mineral is measured in terms of bits per unit cell. Many common minerals crystallize with a complexity measure of just over 200. Mineralogists and crystallographers will perceive a complex mineral has having a measure of around 1000 bits per unit cell, although only about 2.5% of known minerals fall into this category. According to Peter Burns of the University of Notre Dame, in Indian, and colleagues the recently discovered ewingite somehow crams almost 13000 bits into its unit cell with its formula - Mg8Ca8(UO2)24(CO3)30O4(OH)12.138H2O - perhaps hinting at its complexity.
"Minerals at 1,000 bits are considered very complex, but only about 2.5 percent of known minerals receive that designation," confirms Burns. "In comparison, ewingite measures at 12,684.86 bits per unit cell, essentially doubling the measuring stick that mineralogists currently use." The team is currently attempting to synthesize the mineral in the laboratory so that they can better understand the conditions that led to its formation. "The structure of ewingite contains nanometer-scale anionic uranyl carbonate cages that contain 24 uranyl polyhedra, as well as calcium and magnesium cations and water groups located in interstitial regions inside and between the cages," the team reports. "The discovery of ewingite suggests that nanoscale uranyl carbonate cages could be aqueous species in some systems, and these may affect the geochemical behavior of uranium," they add.
Burns muses on the fact that this mineral may well have not existed until people opened up the mine in which it was discovered and allowed the particular temperature, pressure, humidity, and atmospheric conditions to interact with other materials locked in the earth until that time. The researchers are working with the Carnegie Institute to gather existing data on uranium-based minerals. They hope to spot variations in the information we already have about such minerals to determine whether their formation has also arisen through human activities, such as mining.
Ewingite was named after Rodney C. Ewing, who is Frank Stanton Professor in Nuclear Security at Stanford University. The name recognizes his contributions to the fields of mineralogy and nuclear science. The mineral was discovered in the Plavno mine in the Jáchymov ore district, western Bohemia, Czech Republic. An intriguing aside is that this mine is in the same region that provided experimental materials for Marie Curie's pioneering scientific work in the early twentieth century that led to the discovery of what we now know as the elements polonium and radium.
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".
W poniedziałek podczas Światowego Szczytu Społeczeństwa Informacyjnego (WSIS Forum) 2018 w Genewie prezentowali się studenci i naukowcy z naszej uczelni. Do Szwajcarii pojechali na zaproszenie Urzędu Komunikacji Elektronicznej
Już po raz drugi studenci Politechniki Wrocławskiej spędzą noc na pisaniu listów. Spotykają się wieczorem 21 marca w Strefie Kultury Studenckiej, żeby wziąć udział w akcji na rzecz swoich kolegów z niepełnosprawnością
Cheaper biomimetic nanoparticles could be on the cards thanks to researchers at the Houston Methodist Research Institute, Texas, USA. Ennio Tasciotti and his colleagues have shared their recipe so that any laboratory in the world can use it to easily create similar nanoparticles. The work could ultimately lead to a whole new way of delivering pharmaceuticals, for instance.
"We're the only lab in the world doing this," explains Tasciotti, "There are several questions about how our system works, and I can't answer all of them. By giving away the so-called 'recipe' to make biomimetic nanoparticles, a lot of other labs will be able to enter this field and may provide additional solutions and applications that are beyond the reach of only one laboratory. You could say it's the democratization of nanotechnology."
Writing in the journal Advanced Materials, Tasciotti and his colleagues show how to standardize nanoparticle production which allows them to effectively guarantee stability and reproducibility and boost yields. Their approach side-steps the need for costly, high-tech facilities and using readily available and relatively affordable bench top equipment.
"Nanoparticles are generally made through cryptic protocols, and it's very often impossible to consistently or affordably reproduce them," Tasciotti explains. "You usually need special, custom-made equipment or procedures that are available to only a few laboratories. We provide step-by-step instructions so that now everybody can do it."
For most of the history of nanotechnology, particles were made from inorganic and essentially inert materials. However, the need for biologically active and biocompatible nanoparticles has put pressure on scientists to develop nanoparticles from other materials. Tasciotti and his colleagues are pushing the field towards biomimetic nanoparticles that have a composition not dissimilar to the cells of our body and might have physiological functionality that is not inherent in conventional inorganic nanoparticles.
"The body is so smart in the ways it defends itself. The immune system will eventually recognize nanoparticles no matter how well you make them," Tasciotti explains. "In my lab, we make nanoparticles out of the cell membrane of the very same immune cells that patrol the blood stream. When we put these biomimetic, or bioinspired, nanoparticles back in the body, the immune cells do not recognize them as something different, as they're made of their same building blocks, so there is no adverse response." This new type of biomimetic nanoparticle is complex but Tasciotti's recipe for making them is actually incredibly simple, which is part of the reason for publishing the detailed recipe and opening up this avenue of research to other scientists. [E Tasciotti et al Adv Mater (2018); DOI: 10.1002/adma.201702749]
"While our lab will remain fully devoted to this line of research, if somebody else develops some solutions using our protocols that are useful in clinical care, it's still a good outcome," he adds. "After all, the ultimate reason why we are in translational science is for the benefit of the patients."
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".
A battery with organic electrodes can function at a chilly temperature as low as -70 degrees Celsius, according researchers writing in the journal Joule. Such a device could find use in space applications as well as more down to earth uses in the polar regions or other parts of the world that suffer extremely cold conditions periodically.
Conventional rechargeable lithium ion batteries with which we are all familiar require a relatively balmy operating temperature. Chill them to just -20 degrees Celsius and their effectiveness is halved. By -40 Celsius, a temperature not uncommon in extreme environments, and capacity is just one eighth. Part of the problem is the electrode materials and part of the blame lies with the ester electrolyte. Now, Yong-yao Xia of Fudan University in Shanghai, China, and colleagues have turned to polytriphenylamine (PTPAn) for their cathode and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA)-derived polyimide (PNTCDA) for their anode and an ester-based electrolyte that has a lower freezing temperature than the standard electrolytes used. [X Dong et al Joule (2018); DOI: 10.1016/j.joule.2018.01.017]
The problem of sluggish electrolytes has vexed electrochemists for many years. Now, Xia and colleagues have tested an ethyl acetate-based electrolyte, which has a low freezing point and found that it can still conduct electricity even at extremely low temperatures. The choice of organic materials for the electrodes side-steps the problem of relying on lithium intercalation, a process that also becomes sluggish as the temperature falls.
"Benefitting from the ethyl acetate-based electrolyte and organic polymers electrodes, the rechargeable battery can work well at the ultra-low temperature of -70 degrees Celsius," Xia explains. He and his team believe that their work offers a more elegant solution to the problem of battery chill than other attempts that involved using various additives to externally heat the batteries or by using liquefied gas electrolytes. The more elegant solution adds neither extra materials nor weight to the battery.
"Compared to the transition-metal-containing electrodes materials in conventional lithium-ion batteries, organic materials are abundant, inexpensive, and environmentally friendly," Xia adds. He estimates that the price of the electrode materials will also be about one third of the price of electrodes in a lithium-ion battery, potentially cutting costs. However, work remains to be done. The specific energy of the battery is relatively low when compared with commercial lithium-ion batteries. Moreover, the assembly process will need to be optimized to allow it to be mass produced economically.
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".
Using thermoplastic to make a composite part could reduce manufacturing time by 20-30%. could reduce manufacturing time by 20-30% compared to metals or other polymer materials, according to materials specialist Victrex. ‘The aircraft industry has forecast that over 35,000 new aircraft will be required within the next 20 years,’ it said in a press release. ‘Meeting this kind of escalating demand clearly calls for new approaches and new technologies. As a consequence, thermoplastic composites are expected to play an increasingly important role in accelerating future aircraft construction.’
The company says it is partnering with aerospace OEMs and research centers, using its Victrex AE 250 composites product range and related technology while last year Victrex announced it was investing in a joint venture, TxV AeroComposites, with development partner TriMack Manufacturing, to build the necessary supply chain.
‘Supply chain and capacity are important criteria for increasing the amount of thermoplastic composites in future aircraft programs,’ said Tim Herr, director at Victrex. ‘When using high-performance polymers, the initial costs for thermoplastic composites may be much higher. However, when we consider total costs, the equation immediately looks much different.’
This story uses material fro Victrex,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The recent World Pultrusion Conference attracted 150 delegates, a record number, according to the European Pultrusion Technology Association (EPTA), which organized the event.
Taking place in Vienna, Austria on 1-2 March the conference covered growth drivers for the pultrusion industry, potential in existing and emerging applications, and the latest developments in materials, testing and standardisation.
According to the EPTA, pultrusion is one of the few continuous processes for manufacture of composite parts and enables the high volume manufacture of structural profiles with improved mechanical properties and higher quality. Pultruded composites have found a role in numerous industries including construction, transportation, consumer goods, and the electrical and chemical sectors.
‘The record number of 150 participants, coming from North and South America, Europe, India and South Africa, indicates a clear and growing interest in pultrusion globally,’ said Dr Elmar Witten, Secretary, EPTA. ‘The high level of technology and application development activities showcased in the wide-ranging conference programme is evidence of a strong determination to improve the competitiveness of pultruded products and pursue growth opportunities.’
The World Pultrusion Conference is a biennial event and the largest forum for the pultrusion industry in Europe. The next conference will take place in March 2019.
This story uses material from the EPTA,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Carpenter Technology has acquired MB CalRAM LLC, which offers powder-bed fusion additive manufacturing (AM) metal printing services.
California-based CalRAM makes parts for the aerospace, defense, power generation, and oil and gas industries. It has a 25,000 ft2 manufacturing facility and can reportedly produce a range of differentiated parts.
‘This strategic acquisition builds upon our existing additive manufacturing capabilities and provides direct entry into the rapidly expanding part production segment of the additive manufacturing value chain,’ said Tony Thene, Carpenter’s president and CEO. ‘The addition of CalRAM […] is a strong complement to Carpenter’s deep technical experience in producing highly engineered metal powders and wire for additive manufacturing applications, including mission-critical applications such as jet-engine fuel nozzles, rocket-thrust chambers, and orthopedic implants.’
This story uses material from Carpenter,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
PyroGenesis Canada, which makes metal powders for additive manufacturing (AM), has been nominated for an ‘Materials Company of the Year’ at the 3D Printing Industry Awards 2018.
‘We are truly honored to have been recognized by the industry with this shortlist nomination,’ said P Peter Pascali, CEO and president of PyroGenesis. ‘Notwithstanding the outcome, the fact that we were barely known this time last year, and now we are being considered, with such prestigious names, confirms that our strategy to produce powders, once again, for the additive manufacturing industry, was the correct one.’
The 3D Printing Industry Awards take place in London, UK on 17th May 2018.
This story uses material from Pyrogenesis,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Agnieszka Podwin, doktorantka w Zakładzie Mikroinżynierii i Fotowoltaiki PWr zwyciężyła w 8. edycji konkursu „Innowacja jest Kobietą”. Młoda badaczka opracowała m.in. udoskonalone laboratorium na chipie i dozownik gazu wspomagający hodowlę komórkową
Spotkania z wykładowcami, zwiedzanie niedostępnych na co dzień laboratoriów, pokazy oraz szczegóły związane z przebiegiem rekrutacji - to wszystko czekało na maturzystów chcących studiować na PWr, którzy pojawili się na naszych Dniach Otwartych
Lithium-metal batteries are among the most promising candidates for high-density energy storage technology in an expanding range of digital ‘smart’ devices and electrical vehicles. But uncontrolled lithium dendrite growth, which results in poor recharging capability and safety hazards, currently tempers their potential.
Dendrites are needle-like growths that appear on the surface of lithium metal, which is used as the anode, or negative electrode, of the battery. They induce unwanted side reactions that reduce energy density and, at worst, cause shorting of the electrodes that can lead to fires or explosions.
Now, scientists at Arizona State University have found that using a three-dimensional layer of polydimethylsiloxane (PDMS), or silicone, as the substrate for a lithium metal anode can mitigate dendrite formation and thus dramatically extend battery life and diminish safety risks. They report their findings in a paper in Nature Energy.
According to Hanqing Jiang, a professor in Arizona State University's School for Engineering of Matter, Transport and Energy and lead researcher of the study, the findings also have relevance for both lithium-ion and lithium-air batteries, as well as implications for other metal-anode-based batteries.
"Almost all metals used as battery anodes tend to develop dendrites," explained Jiang. "For example, these findings have implications for zinc, sodium and aluminum batteries as well."
Jiang said that, rather than approaching the problem from a materials or electrochemical perspective, he and his colleagues looked for solutions as mechanical engineers. "We already know that tiny tin needles or whiskers can protrude out of tin surfaces under stress, so by analogy we looked at the possibility of stress as a factor in lithium dendrite growth."
The first round of research involved adding a layer of PDMS to the bottom of a battery anode. "There were remarkable reductions in dendrite growth," said Jiang. The researchers discovered this was because deformations of the PDMS substrate in the form of ‘wrinkles’ helped to relieve stress accumulating inside the lithium metal.
"This is the first time convincing evidence shows that residual stress plays a key role in the initiation of lithium dendrites," said Jiang.
In addition to obtaining a fundamental understanding of the lithium dendrite growth mechanism, Jiang's group also came up with a smart way to utilize the stress-relieving phenomenon to extend the life of lithium-metal batteries while maintaining their high energy density. The solution is to give the PDMS substrate a three-dimensional form with a lot of surface area.
"Envision sugar cubes that contain a lot of small internal pores," explained Jiang. "Inside these cubes, the PDMS forms a continuous network as the substrate, covered by a thin copper layer to conduct electrons. Finally, lithium fills the pores. The PDMS, which serves as a porous, sponge-like layer, relieves the stress and effectively inhibits dendrite growth."
"By synergistically combing with other lithium dendrite suppression methods such as new electrolyte additives, the finding has broad implications for making lithium-metal batteries a safe, high-density, long-term energy storage solution," said Ming Tang, a research team member at Rice University. "Potential applications range from personal electronic devices to powering electric cars for exceptionally longer periods to being the back-up electric supply for solar power grids."
Most people have felt the sting from grabbing a doorknob after walking across a carpet or seen how a balloon will stick to a fuzzy surface after a few moments of vigorous rubbing. While the effects of static electricity have been fascinating casual observers and scientists for millennia, certain aspects of how the electricity is generated and stored on surfaces have remained a mystery.
Now, researchers have discovered more details about the way certain materials hold a charge even after two surfaces separate, information that could help improve devices that leverage such energy as a power source.
"We've known that energy generated in contact electrification is readily retained by the material as electrostatic charges for hours at room temperature," said Zhong Lin Wang, professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. "Our research showed that there's a potential barrier at the surface that prevents the charges generated from flowing back to the solid where they were from or escaping from the surface after the contacting."
In their research, which is reported in a paper in Advanced Materials, the researchers found that electron transfer – rather than ion transfer – is the dominant process for contact electrification, also known as triboelectrification, between two inorganic solids. This finding explains some of the characteristics already observed about static electricity.
"There has been some debate around contact electrification – namely, whether the charge transfer occurs through electrons or ions and why the charges retain on the surface without a quick dissipation," Wang said.
It's been eight years since Wang's team first published research on triboelectric nanogenerators, which employ materials that create an electric charge when in motion and could be designed to harvest energy from a variety of sources such as wind, ocean currents or sound vibrations. "Previously we just used trial and error to maximize this effect," Wang said. "But with this new information, we can design materials that have better performance for power conversion."
The researchers developed a method using a nanoscale triboelectric nanogenerator – composed of layers either of titanium and aluminum oxide or titanium and silicone dioxide – to help quantify the amount of charge accumulating on surfaces during moments of friction.
The method was capable of tracking the accumulated charges in real time and worked over a wide range of temperatures, including very high ones. The data from the study indicated that the characteristics of the triboelectric effect – namely, how electrons flowed across barriers – were consistent with the electron thermionic emission theory.
By designing triboelectric nanogenerators that could withstand testing at high temperatures, the researchers also found that temperature played a major role in the triboelectric effect. "We never realized it was a temperature-dependent phenomenon," Wang said. "But we found that when the temperature reaches about 300°C, the triboelectric transfer almost disappears."
The researchers tested the ability of surfaces to maintain a charge at temperatures ranging from about 80°C to 300°C. Based on their data, the researchers then proposed a mechanism to explain why the triboelectric effect weakens at higher temperatures.
"As the temperature rises, the energy fluctuations of electrons become larger and larger," the researchers wrote. "Thus, it is easier for electrons to hop out of the potential well, and they either go back to the material where they came from or emit into air."
Alzheimer’s disease affects about 17 million people worldwide, causing severe memory and cognitive impairment. This often has a significant effect on patients’ mental health, leading to depression, stress and anxiety. It’s also an expensive disease: the World Health Organization (WHO) estimates it costs $600 billion, making it a global socio-economic problem.
While researchers continue to unravel the mechanisms behind the disease and work out how to tackle it, it’s important that patients get the best possible care. Regular monitoring of the disease is part of this, and we’re working on a way to make this faster, easier and cheaper.
Alzheimer’s disease is caused by high levels of a peptide called beta-amyloid in the brain, which leads to the degeneration of brain cells. Doctors use different types of scans and immunoassays, like MRI and ELISA, to estimate the amount of beta-amyloid in the brain. This gives them an indication of how the disease is progressing. But these scans require big, expensive equipment, and trained professionals. This can be challenging, particularly in developing countries and rural settings.
Beta-amyloid can also be found in lower levels in blood, so it’s a useful biomarker to diagnose and monitor disease progression. There is a test that doctors can use to monitor beta-amyloid in the blood, but it’s not very sensitive and takes a long time. The test, called ELISA, requires relatively big samples and takes six to eight hours to produce a result – this isn’t so helpful if a doctor wants to know a patient’s status immediately.
A new generation of tests
In our new review, published in Biosensors and Bioelectronics, we looked at each of the methods available to measure beta-amyloid concentration in brain tissue and in blood. None of the existing tests can be done at the bedside and all need special expertise and large samples. They also take a long time to generate a useful result.
Even though the existing technologies we looked at are well established, we need to move towards small sample, high accuracy tests that can be used in all environments, from developed countries to rural settings.
In our lab, we develop portable sensors that can help patients by supporting personalized therapeutics. For example, we have developed an electrochemical sensor and tested it to detect cortisol – a stress hormone. It’s far better than the conventional technique, ELISA; it’s more sensitive and faster.
Using similar technology, we’re now working towards something that can detect beta-amyloid. Our goal is to develop a test that’s sensitive, small and affordable – one that can measure beta-amyloid in the blood at tiny concentrations in just half an hour.
The drugs used to treat Alzheimer’s disease can have side effects, so it’s better for patients not to overdose. With the right data, doctors can respond quickly to changes in a patient’s brain by reducing or increasing their dose.
A sensitive, fast test would enable doctors to test a patient and see the results during the same appointment, so they could adjust medication to match the patient’s needs. It’s really a step towards personalized Alzheimer’s therapy. Ultimately, it could greatly improve people’s quality of life in the future.
To develop the new biosensor, we need lots of biological samples from different places, species and stages of disease. This is challenging, and we’re still working on it. Once we’ve got all the samples, we will need to validate the system and compare it to the other tests available to see if it’s really better. It will take some time to reach the market, but we’re confident this could make a real difference in the future.
People with diabetes might soon be able to manage their disease more effectively and reduce their risk of long-term complications using wearable glucose monitoring systems. “Scientists are getting closer to producing such skin-worn flexible devices,” says Joseph Wang of the Department of Nanoengineering at the University of California, San Diego in the United States. Wang and colleagues review progress in the field in the journal Talanta.
Millions of people with diabetes worldwide, currently monitor their blood glucose levels using inconvenient and painful sampling of blood from their fingertips. Without doing this they can't effectively adjust their insulin levels to keep their blood glucose within a safe range.
However, fingertip tests do not continuously monitor levels and the inconvenience of repeatedly performing tests leads some patients to check less often than is desirable. Less effective monitoring increases the risk of the long-term complications of diabetes, including damage to nerves, eyes and the circulatory system. It also offers less protection against the extreme swings into high or low blood glucose levels that can cause disorientation, unconsciousness or even death.
Several research groups are reporting progress in developing devices that monitor blood glucose non-invasively, using electrochemical sensors worn on the skin. “Achieving reliable non-invasive glucose biosensing will represent a real breakthrough in the management of diabetes,” says Wang.
The sensors being developed and currently under trial include small meters strapped to the arm, skin patches and even tattoos. The technology can then transmit data wirelessly to handheld devices.
More than 10 years ago the US Food and Drug Administration approved a wrist-worn system called GlucoWatch, manufactured by Cygnus Inc. This sensed glucose levels in the skin and used these to calculate the likely levels in the blood. Despite promising trials, this device was soon removed from the market due to problems with calibration and skin irritation.
Wang and his colleagues are working on an ultra-thin and flexible sensor that is applied to the skin. This avoids the discomfort found with GlucoWatch and early tests are promising. Future work will focus on larger-scale trials and efforts to make the system more physically robust.
Other researchers are exploring how skin patches can use the glucose levels in sweat as an indicator of overall blood glucose concentration.
Considerable challenges lie between the current state of research and the commercialization of reliable and robust continuous monitoring devices. The most crucial of these is to establish a correlation between what the sensors detect and the real blood glucose concentrations. Further research is also needed to account for the effect of different levels of exercise and differences due to the location of the sensors.
“The development of these skin-based glucose monitors is just beginning,” cautions Wang. He emphasizes the further refinements in accuracy and calibration and extensive clinical trials required before the hopes become realities. In the longer term, however, Wang and his co-authors conclude that wearable 24/7 glucose monitoring is “poised to significantly increase its impact on medicine,” making diabetes control simpler and increasingly effective.
An ocean of plastic. That is the picture painted in our minds when we imagine the estimated eight million tonnes of plastic waste entering our marine ecosystems every year. Such an unmanageable volume of plastic has devastating environmental consequences that are only just starting to become apparent.
“Plastics need to be produced and re-used in a sustainable way,” says Dr Guneet Kaur, co-author of the study. “To be sustainable, processes should not just be environmentally friendly and socially acceptable – but also economically viable and even profitable.”
In a circular economy, there is no waste. The concept looks beyond the traditional industrial mantra of “take, make, dispose” and instead creates an industrial system with the environment in mind. It is an idea that has been championed by the European Union for years.
After looking at the work of several EU-funded projects on food and agricultural waste, the Hong Kong-based team examined the ways in which food waste can be converted into plastic in a biorefinery. They used the work of research groups around the world, including their own lab, to illustrate that inexpensive and renewable sugars can be used to produce high-value plastics.
“Bio-plastics have come a long way in recent years,” says project lead Dr Carol Sze Ki Lin. “A joint ventureof global companies that includes Coca-Cola is about to open a manufacturing plant for bio-plastic bottles in Belgium. It will have the capacity to produce 50,000 tonnes of bio-based polyethylene furanoate (PEF) a year.”
PEF is a bio-based and recyclable polymer that is projected to replace conventional petroleum-based polyethylene terephthalate (PET) because of its superior properties that make it suitable for a wider range of applications. Dr Lin adds, “The global market for bio-plastics is estimated to reach 30.8 billion dollars by 2020 – and PEF, which has not reached its full market potential yet – is expected to hold a large share of the market.”
Key to the success of a circular plastics economy is waste management – and this comes through recyclability, not biodegradability. A recyclable product means that material is retained in the recirculation loop; it can be re-made into new value-added products. If it can biodegrade, a valuable resource is removed which could impact profitability.
Although PEF products can be successfully recycled into other usable products, it is no more biodegradable than petroleum-based PET. With the correct protocols in place to ensure recycling, PEF bioplastics are an ideal entrant to the circular plastic economy. Dr Lin’s team hopes to contribute to this and is improving the production of bio-sugar from restaurant waste.
Organic solar cells have great potential as a source of clean electrical energy, but so far they have not been cheap, light and flexible enough for widespread use. Now, a team of researchers led by André Taylor, an associate professor in the Department of Chemical and Biomolecular Engineering at NYU Tandon School of Engineering, has found an innovative and promising way to improve organic solar cells and spur their use in various applications.
Most organic solar cells use fullerenes, spherical molecules of carbon. The problem, explains Taylor, is that fullerenes are expensive and don't absorb enough light. Over the past 10 years, he has made significant progress in improving organic solar cells, and has recently focused on using non-fullerenes, which until now have been inefficient. However, he says, "the non-fullerenes are improving enough to give fullerenes a run for their money."
Think of a solar cell as a sandwich, Taylor says. The ‘meat’ or active layer – made of electron donors and acceptors – is in the middle, absorbing sunlight and transforming it into electricity (electrons and holes), while the ‘bread’, or outside layers, consist of electrodes that transport that electricity. His team's goal was to have the cell absorb light across as large a spectrum as possible using a variety of materials, yet at the same time allow these materials to work together.
"My group works on key parts of the 'sandwich,' such as the electron and hole transporting layers of the 'bread,' while other groups may work only on the 'meat' or interlayer materials," says Taylor. "The question is: how do you get them to play together? The right blend of these disparate materials is extremely difficult to achieve."
Using a squaraine molecule in a new way – as a crystallizing agent – did the trick. "We added a small molecule that functions as an electron donor by itself and enhances the absorption of the active layer," Taylor explains. "By adding this small molecule, it facilitates the orientation of the donor-acceptor polymer (called PBDB-T) with the non-fullerene acceptor, ITIC, in a favorable arrangement."
This solar architecture also uses another design mechanism that the Taylor group pioneered known as a FRET-based solar cell. FRET, or Förster resonance energy transfer, is an energy transfer mechanism first observed in photosynthesis. Using a new polymer and non-fullerene blend with squaraine, the team were able to convert more than 10% of solar energy into power. Just a few years ago this was considered too lofty a goal for single-junction polymer solar cells. "There are now newer polymer non-fullerene systems that can perform above 13%, so we view our contribution as a viable strategy for improving these systems," Taylor says.
The organic solar cells developed by his team are flexible and could one day find use in electric vehicles, wearable electronics and backpacks for charging cell phones. Eventually, they could contribute significantly to the supply of electrical power. "We expect that this crystallizing-agent method will attract attention from chemists and materials scientists affiliated with organic electronics," says Yifan Zheng, Taylor's former research student and lead author of a paper on this work in Materials Today.
Evonik is planning to build a new plant to produce polymer polyamide 12 (PA 12), aiming to increase its overall PA 12 capacity by more than 50%. Polyamide 12 is made for growth markets such as the automotive industry, oil and gas pipelines, and in 3D printing.
Evonik plans to invest approximately €400 million in the PA 12 complex at its largest site, Marl Chemical Park in North Rhine-Westphalia, Germany. The existing PA 12 production will have additional manufacturing facilities for the polymer and its precursors. The complex is expected to become operational in early 2021.
‘This investment is a perfect fit to our strategy of consistent focus on specialty chemicals since polyamide 12, as a high-performance polymer for specialty applications, is an important part of our strategic Growth Engine Smart Materials,’ said Christian Kullmann, chairman of the Evonik executive board.
The PA 12 market is posting annual growth rates exceeding 5% worldwide, outpacing the global gross domestic product. In the specialty application of 3D printing, growth rates reach double digits, the company said.
This story uses material from Evonik,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
3D Systems has reported a 7% revenue growth to US$177.3 million in Q4, compared to US$165.9 million in the same period of the previous year.
For the full year 2017, revenue increased two percent to US$646.1 million compared to US$633.0 million in 2016.
We are pleased with the growth in revenue driven by healthcare, materials, software and on demand manufacturing, as well as more balanced regional execution experienced in the fourth quarter,” said Vyomesh Joshi (VJ), chief executive officer, 3D Systems.‘We made significant progress in 2017 to stabilize and turn around the company, and we put in place the foundation for scalable growth. This is a multi-year transformation process, but we are pleased with the progress we have made thus far to position the company for long-term growth and profitability. We are focused on execution, driving operational efficiencies and bringing our new innovative and disruptive products to market to drive the shift to 3D production.’
This story uses material from 3D Systems,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Scientists have used lab experiments to retrace the chemical steps leading to the creation of complex hydrocarbons in space, showing pathways to forming two-dimensional (2D) carbon-based nanostructures, including graphene, in a mix of heated gases.
The latest study, which featured experiments at the US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), could help to explain the presence of pyrene and similar carbon-based compounds in some meteorites.
A team of scientists, including researchers from Berkeley Lab and the University of California, Berkeley, participated in the study, which is reported in a paper in Nature Astronomy. The study was led by scientists at the University of Hawaii at Manoa, and also involved theoretical chemists at Florida International University.
"This is how we believe some of the first carbon-based structures evolved in the universe," said Musahid Ahmed, a scientist in Berkeley Lab's Chemical Sciences Division, who joined other team members to perform experiments at Berkeley Lab's Advanced Light Source (ALS). "Starting off from simple gases, you can generate one-dimensional and two-dimensional structures, and pyrene could lead you to 2D graphene. From there you can get to graphite, and the evolution of more complex chemistry begins."
Pyrene has a molecular structure composed of 16 carbon atoms and 10 hydrogen atoms. Researchers found that the same heated chemical processes that give rise to the formation of pyrene are also relevant to combustion processes in vehicle engines, for example, and the formation of soot particles.
The latest study builds on earlier work that analyzed hydrocarbons with smaller molecular rings that have also been observed in space, including in Saturn's moon Titan – namely benzene and naphthalene. "When these hydrocarbons were first seen in space, people got very excited," said Ralf Kaiser, one of the study's lead authors and a chemistry professor at the University of Hawaii at Manoa. "There was the question of how they formed." Were they purely formed through reactions in a mix of gases, or did they form on a watery surface, for example?
Ahmed said there is an interplay between astronomers and chemists in this detective work, which seeks to retell the story of how life's chemical precursors formed in the universe. "We talk to astronomers a lot because we want their help in figuring out what's out there," Ahmed said, "and it informs us to think about how it got there." Kaiser noted that physical chemists, on the other hand, can help shine a light on reaction mechanisms that can lead to the synthesis of specific molecules in space.
Pyrene belongs to a family known as polycyclic aromatic hydrocarbons (PAHs) that are estimated to account for about 20% of all the carbon in our galaxy. PAHs are organic molecules composed of a sequence of fused molecular rings. To explore how these rings develop in space, scientists work to synthesize these molecules and other surrounding molecules known to exist in space.
"You build them up one ring at a time, and we've been making these rings bigger and bigger," explained Alexander Mebel, a chemistry professor at Florida International University who participated in the study. "This is a very reductionist way of looking at the origins of life: one building block at a time."
For this study, the researchers explored the chemical reactions that stem from combining a complex hydrocarbon known as the 4-phenanthrenyl radical with acetylene. The 4-phenanthrenyl radical has a molecular structure that includes a sequence of three rings and contains a total of 14 carbon atoms and nine hydrogen atoms, while acetylene comprises two carbon atoms and two hydrogen atoms.
Chemical compounds needed for the study were not commercially available, said Felix Fischer, an assistant professor of chemistry at UC Berkeley who also contributed to the study, so his lab prepared the samples. "These chemicals are very tedious to synthesize in the laboratory," he said.
At the ALS, researchers injected the gas mixture into a microreactor that heated the sample to a high temperature to simulate the proximity of a star. The ALS generates beams of light, from infrared to X-ray wavelengths, to support a range of science experiments by visiting and in-house researchers.
The mixture of gases was jetted out of the microreactor through a tiny nozzle at supersonic speeds, arresting the active chemistry within the heated cell. The research team focused a beam of vacuum ultraviolet light from the synchrotron on the heated gas mixture that knocked away electrons (an effect known as ionization).
They then analyzed the chemistry taking place using a charged-particle detector that measured the varied arrival times of the particles that formed after ionization, as the arrival times carried the tell-tale signatures of the parent molecules. These experimental measurements, coupled with Mebel's theoretical calculations, helped researchers to see the intermediate steps of the chemistry at play and to confirm the production of pyrene in the reactions.
Mebel's work showed how pyrene (a four-ringed molecular structure) could develop from a compound known as phenanthrene (a three-ringed structure). These theoretical calculations can be useful for studying a variety of phenomena, "from combustion flames on Earth to outflows of carbon stars and the interstellar medium," Mebel said.
"Future studies could study how to create even larger chains of ringed molecules using the same technique, and to explore how to form graphene from pyrene chemistry," Kaiser added.
Other experiments conducted by team members at the University of Hawaii will explore what happens when researchers mix hydrocarbon gases in icy conditions and simulate cosmic radiation to see whether that may spark the creation of life-bearing molecules.
"Is this enough of a trigger?" Ahmed said. "There has to be some self-organization and self-assembly involved" to create life forms. "The big question is whether this is something that, inherently, the laws of physics do allow."
Ponad 70 kół naukowych i organizacji studenckich działających na Politechnice Wrocławskiej zaprezentowało się w Serowców. Studenci przygotowali wiele atrakcji – były pokazy, konkursy i mnóstwo dobrej zabawy
Kilkaset osób wzięło udział w uroczystościach z okazji 50. rocznicy wydarzeń Marca ’68 na Politechnice Wrocławskiej. W spotkaniu uczestniczyli m.in. organizatorzy tamtych protestów i obecni studenci PWr. Gościem obchodów był premier RP Mateusz Morawi
Gurit and Elbe Flugzeugwerke (EFW) have signed a new framework contract for the development and supply of aerospace materials.
EFW is a 55:45 joint venture of ST Aerospace and Airbus, based in Dresden, Germany and offers passenger-to-freighter aircraft conversions, maintenance and repair of Airbus aircraft, and the development and manufacturing of flat fiber-reinforced composite components for structures and interiors of the entire Airbus family of aircraft.
The three-year agreement will take effect from 1 January 2019 and builds on the decennial business relationship between both companies. The extended framework contract comprises the production and supply of existing aerospace materials as well as the joint development and qualification of new material technologies to make cabin interiors for Airbus passenger airplanes. The total value of the three-year agreement is at around CHF 25 million over the contract period.
‘We are very pleased and honoured to intensify and reinforce our long-standing partnership with Elbe Flugzeugwerke,’ said Stefan Gautschi, general manager at Gurit. ‘This new contract provides both parties and our partners with continuity and reliability for the future.’
This story uses material from Gurit,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Replacing metal components like wires and interconnects in electronic devices could reduce production costs and waste management problems. Some metals used in electronic devices can be toxic if leached into the environment or produce air pollutants when incinerated. Lighter, cheaper, less toxic carbon-based materials make an attractive alternative.
“We modified commercial near field communication (NFC) devices, replacing classical, all-metal antennas with new ones composed solely of carbon atoms,” explains Vincenzo Palermo of the National Research Council of Italy and Chalmers University of Technology in Sweden, who led the effort with colleagues from several European companies including STMicroelectronics.
The antennas are based on highly conductive graphene paper (G-paper), which the team fabricated by simply compressing stacks of graphene nanoplatelets. Unlike other alternative approaches, using G-paper does not require chemical etching of metals or high-temperature annealing during processing.
“Given that the properties of G-paper are different from metals, we had to tune the shape and electrical properties (resistance, inductance, and capacitance) of the carbon antennas to render them fully compatible with commercial hardware and software,” says Palermo.
Moreover, the G-paper devices can be deposited on a wide range of rigid and flexible substrates such as plastic, cardboard, paper, and even silk. Even after repeated bending, the graphene-based antennas show minimal change in resistance because individual nanoplatelets slide easily over one another without losing their strong inter-sheet electrical connection.
“The antennas can receive and transmit data with conventional mobile phones, electronic locks, and other devices, giving the approach a high technology readiness level,” Palermo told Materials Today. “We are now looking for industrial partners interested in evaluating the mass production potential of this technology.”
The antennas could be ideal for disposable electronic devices like smart cards, NFC tags or bracelets, or electronic card keys. G-paper devices have the advantage of being more corrosion resistant and thermally, chemically, and mechanically stable than their metal counterparts, opening up new opportunities in wearable electronics or biomedicine. Moreover, there is no danger of disposable devices releasing heavy metal ions into the environment during production or disposal.
“It was already known that carbon- and, in particular, graphene-based materials and coatings can be used as antennas,” points out Palermo. “But our work demonstrates that it is possible to achieve high conductivity (>105 S/m) with G-paper, not achievable up to now with standard graphene inks or coatings.”
Researchers at Oregon State University (OSU)'s College of Engineering have taken a key step toward the rapid manufacture of flexible computer screens and other stretchable electronic devices, including soft robots.
The advance by a team within the college's Collaborative Robotics and Intelligent Systems Institute paves the way toward the 3D printing of tall, complicated structures using a highly conductive gallium alloy known as galinstan, which is liquid at room temperatures. The researchers found that adding nickel nanoparticles to galinstan thickens it into a paste with a consistency suitable for additive manufacturing.
"The runny alloy was impossible to layer into tall structures," said Yigit Mengüç, assistant professor of mechanical engineering and co-corresponding author of a paper on this research in Advanced Materials Technologies. "With the paste-like texture, it can be layered while maintaining its capacity to flow, and to stretch inside of rubber tubes. We demonstrated the potential of our discovery by 3D printing a very stretchy two-layered circuit whose layers weave in and out of each other without touching."
Gallium alloys are already being used as the conductive material in flexible electronics; the alloys have low toxicity and good conductivity, plus they're inexpensive and ‘self-healing’ – able to attach back together at break points. But prior to the modification developed at OSU, which saw the researchers using sonication – the energy of sound – to mix the nickel particles and oxidized gallium into the liquid metal, the alloys' printability was restricted to two dimensions.
For this study, researchers printed structures up to 10mm high and 20mm wide. "Liquid metal printing is integral to the flexible electronics field," said co-author Dogan Yirmibesoglu, a robotics PhD student at OSU. "Additive manufacturing enables fast fabrication of intricate designs and circuitry."
Examples of flexible electronics include: electrically conductive textiles; bendable displays; sensors for torque, pressure and other types of strain; wearable sensor suits, such as those used in the development of video games; antennae; and biomedical sensors. "The future is very bright," Yirmibesoglu said. "It's easy to imagine making soft robots that are ready for operation, that will just walk out of the printer."
The gallium alloy paste demonstrates several features new to the field of flexible electronics, added co-corresponding author Uranbileg Daalkhaijav, a PhD candidate in chemical engineering. "It can be made easily and quickly. The structural change is permanent, the electrical properties of the paste are comparable to pure liquid metal and the paste retains self-healing characteristics."
Future work will explore the exact structure of the paste, how the nickel particles are stabilized and how the structure changes as the paste ages.
The protein albumin is already responsible for many vital processes in the human body. Now chemists at Martin Luther University Halle-Wittenberg (MLU) in Germany have developed a method for producing various albumin-based gels, which they say could find use as innovative drug carrier systems that more easily reach the bloodstream. They report their work in a paper in Biomaterials Science.
Albumin is a protein found in large quantities in the blood of all mammals: human blood contains up to 60 grams per liter. "Albumin is responsible for many important processes in the body. It can penetrate cell membranes and is thus able to transport essential substances into the cells. It also helps to detoxify cells," says Dariush Hinderberger, a chemist at MLU. He has been investigating albumin for more than 10 years, studying the protein's structure, dynamics and transport properties. Albumin is already being used by the pharmaceutical industry to produce vaccines and medicines, but not in gel form.
"Until now albumin gels have been a somewhat annoying by-product of normal lab work," says Hinderberger. However, in future the gels could be used to produce so-called drug-delivery implants. These would be injected into the patient and then slowly broken down by the body, releasing their drug cargo over a long period of time and thus saving patients from having to undergo repeated injections. "But in order to see whether potential albumin-based drug carrier systems can be developed, it is first necessary to understand how and why the gels form," says Hinderberger, summarising the idea behind his new study.
"In order to see whether potential albumin-based drug carrier systems can be developed, it is first necessary to understand how and why the gels form."Dariush Hinderberger, Martin Luther University Halle-Wittenberg
In response, the chemists at MLU investigated various albumin solutions. "We wanted to find out what exactly happens to the protein particles and their structure when we modify certain properties," says Hinderberger. First, the researchers tested how the solution's pH value affects gel formation; then they heated up the liquid and analyzed what changes occurred and at what stage.
With the aid of infrared spectroscopy, the group was able to demonstrate how the structure of albumin changes when exposed to heat. This causes the protein tangle to open up, allowing it to more easily clump together with other substances to produce the gel. Based on these findings the research group was able to produce a different, much softer, gel by slowing down the gel formation process, which they did by lowering the temperature and choosing a solution with a relatively neutral pH value. "Under these conditions there was little change to the structure of the individual albumin molecules from which the other basic mechanical properties of the gel stem," explains Hinderberger.
Finally, the researchers pursued the question of whether albumin gels are principally suited to act as drug carriers. In initial investigations they were able to show that fatty acids bind well to the gel. However, follow-up studies will be needed to find out whether the albumin gels are also suitable for transporting pharmaceutical agents in the human body.
The board of GKN plc has announced that the company has reached agreement with Dana Incorporated to combine GKN’s Driveline business and Dana to create Dana plc, a global leader in vehicle drive systems.
GKN says that this represents an acceleration of GKN’s strategy of separating its aerospace and driveline businesses, while also providing improved value to its shareholders. Anne Stevens, Chief Executive of GKN, and Richard Parry-Jones, independent non-executive director of GKN, will become non-executive directors of Dana plc.
‘This combination of GKN Driveline and Dana will create a US and UK led global market leader in vehicle drive systems,’ said Mike Turner, chairman of GKN. ‘The synergies between these two businesses and our complementary product portfolios make this a great deal for GKN shareholders.’
GKN ads that it is continuing to pursue the sale of its non-core businesses, including powder metallurgy.
This story uses material from GKN,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Kordsa has outlined its participation in JEC World 2018, the biggest composite technology show of the world.
The reinforcement company shared its expanding product portfolio and new technologies with the visitors, while Kordsa’s CEO Ali Çaliskan was one of the jury members which evaluated a total of 30 projects in 10 different categories at JEC Innovation Awards Ceremony.
‘As a member of a brand that embraces open innovation, I believe that every project in the competition, whether it is awarded or not, will be a significant contribution to the industry,’ said Çaliskan in his speech.
This story uses material from Kordsa,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Additive manufacturing (AM) company Renishaw has been shortlisted for Company of the Year at the PLC Awards 2017.
This marks the first time Renishaw has been shortlisted in the category, which is reportedly awarded to a company that has demonstrated long-term success. In March 2011, Renishaw was awarded the Best Technology Award and the following year, it was nominated again in the same category.
‘Renishaw has had an extremely strong year, growing in turnover, profits and people,’ said Chris Pockett, head of communications at Renishaw. ‘Since 2009, the company has grown from 1,850 staff to 4,500 employees globally and, this year, we are taking on a record number of apprentices.
This story uses material from Renishaw,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Renishaw says that it is contributing its additive manufacturing (AM) specialist knowledge to European machine tool trade association, CECIMO. The trade body represents national associations of machine tool builders across 15 European countries and Renishaw senior manager, Stewart Lane, was appointed to the CECIMO board in 2015.
As part of this role, Lane represents UK industry's interests at European level and has attended seminars addressing the challenges in the AM industry to help form European industrial policy. Further to this, Lane has attended a EU parliament's debating sessions to help discuss and form industrial policy and strategy.
Renishaw has also contributed to CECIMO's digitalisation campaign, which promotes the opportunities, benefits and challenges of digitalisation and how it can impact the future of the machine tool industry.
‘Renishaw is looking at how it can further support CECIMO and the good work it does,’ said Lane. ‘It is important for UK industry to have close ties and representation in Europe, in a time when relationships are changing. This means Renishaw's relationship with CECIMO is more important than ever before.
‘Additive manufacturing is extremely important to the EU industrialisation agenda,’ he continued. ‘Europe is looking to new ways to improve its productivity and maintain its competitiveness compared with leading counterparts – finding new and innovative ways of manufacturing is key to this. Additive manufacturing and its associated technologies are therefore crucial to European strategy.’
‘The European strategy for AM should go beyond research funding and encompass a wide range of policy and regulatory areas to accelerate the market uptake of AM,’ said Filip Geerts, director general of CECIMO. ‘These include the development of standards, the improvement of access to finance conditions especially for SMEs, promotion of awareness-raising campaigns, skills development initiatives, intellectual property protection as well as focus on qualification and certification procedures.’
This story uses material from Renishaw,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Concept Laser says that has successfully 3D printed an oil header, a part that wets a thread with oil that is usually conventionally machined as part of the assembly of common rail injectors (CRI).
The part, commissioned by engineering company Bosch, has been introduced at a plant for CRI production in Bamberg and another four plants in Korea, Turkey, Germany and France.
According to Concept Laser, the part had to ensure that the thread was only wet with oil on the upper thread geometry, but not on the bottom side. The material for the new oil header also had to be high-strength and of course non-corrosive. Concept Laser opted for CoCr as the material along with a small Mlab cusing as the production machine, which is used to produce delicate parts with a 100W laser. The company also had to redesign of the oil channels to improve the wetting of the thread.
This story uses material from Concept Laser,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The European Composites Industry Association (EuCIA) is launching a survey to look into the next stage of development of its Eco Impact Calculator for composites. The online resource is being used by companies to support the business case for the selection of a composite product based on its overall life cycle performance.
The Eco Impact Calculator was launched in July 2016, and the number of users of the tool – including designers, manufacturers and end-users of composite products, materials suppliers and researchers – has been increasing and feedback has been positive, according to the association. The survey will help EuCIA identify future industry needs and direct its long term development program for the tool. The survey, which can be found here, is open to all composites industry professionals.
‘Communicating the sustainability of composites is a long term strategy for EuCIA and the Eco Impact Calculator is an important component of this,’ said Roberto Frassine, EuCIA’s president. ‘It is a ‘living’ tool which must continue to develop as composites technologies advance and business and legislative landscapes evolve. We encourage all interested parties to submit their feedback and opinions so that we can determine the future path for this resource and further increase its value to the composites industry.’
This story uses material from EuCIA,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The organizers of JEC World says that it had more than 1,300 exhibitors and 42,445 visitors from 115 countries.
‘The ability of JEC Group to gather the whole composites industry under one roof over three days lies in the fact that we always initiate new precursory programs to the service of composites professionals.’ said Frédérique Mutel, JEC group president and CEO.
This year JEC initiated new programs such as the Composite Challenge, allowing 10 PhD students to pitch their thesis in front of the industry, the Start Up Booster and Innovation Award Programs to accelerate relations between innovative companies with investors or established enterprises.
Dirk Ahlborn, CEO of Hyperloop opened the Startup Booster ceremony by supporting the spirit of ingenuity in the industry, while Dayton Horvath, iadditive manufacturing consultant presented his vision of how to apply artificial intelligence to composite materials and manufacturing.
A first at the show this year was the introduction of public votes to elect favorite projects among two JEC programs promoting innovation. The Public Choice Award For Startup Booster was Inca-Fiber (Germany) with 62.36% of the 2,221 votes, while the Public Choice Award For Jec Innovation Awards wasinfusion technology for an aircraft wing by AeroComposit JSC (Russia) gaining 20.96% of the 4,126 votes.
This story uses material from JEC,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Perovskite materials promise low-cost, highly efficient, flexible solar photovoltaic devices. But the best power conversion efficiencies reported to date have been for polymer-based electron- and hole-conducting layers, which are highly sensitive to air and moisture.
The team, led by Chang Kook Hong, synthesized p-type nanoporous nickel oxide (NiOx) thin films as the hole transport layer (HTL). The pinhole-free nanoarchitecture is optically transparent and enables higher hole conduction than conventional organic/polymeric hole-conducting layers. But since this perovskite material is highly sensitive to air, the researchers added an air-stable, n-type ZnO nanoparticle electron transport layer (ETL) over the top.
“The nanoporous NiOx facilitates high hole mobility with great stability,” explains Sawanta S. Mali, first author of the study. “The nanoporous architecture provides easier hole transportation through the nanowalls, while the porous structure provides an excellent perovskite/NiOx interface.”
The NiOx also serves as a more effective charge extraction layer for the perovskite than traditional polymeric materials. The result is that p-i-n type inverted perovskite solar cells based on the NiOx thin films show fast electron transportation and low recombination rate, contributing to an efficiency of over 19%.
“The highly stable p-type NiOx HTL and n-type ZnO ETL capping layers are the best choice for highly efficient, air-stable perovskite solar cells,” says Mali. “The developed inorganic p-type NiOx HTL and n-type ZnO ETL protects the perovskite layer from air and avoids metal diffusion.”
The NiOx-based solar devices are much more stable in air than polymer-based alternatives. Without additional encapsulation, the devices showed little deterioration in performance after more than five months. By contrast, polymer-based devices deteriorated over the first few days and were completely dead within five days.
Currently, the hole-electron mobility is still rather low, but the team is confident that suitable doping could improve the situation. The researchers are now working on Li-doped NiOx and Mg-ZnO to boost hole and electron mobility.
“Large-area deposition using spin coating is also a big obstacle,” admits Mali. “Other coating techniques such as ultrasonic spray or roll-to-roll processes would be the best choice to move toward commercialization for this type of PSCs,” he suggests.
The researchers are now working on ultrasonic spray techniques for large area perovskite devices that they believe will offer a new approach to highly efficient, air-stable solar cells.
Researchers from the University of Illinois at Chicago (UIC) and Lawrence Berkeley National Laboratory have developed a new technique that lets them pinpoint the location of chemical reactions happening inside lithium-ion batteries in three dimensions at the nanoscale level. This new technique is reported in a paper in Nature Communications.
"Knowing the precise locations of chemical reactions within individual nanoparticles that are participating in those reactions helps us to identify how a battery operates and uncover how the battery might be optimized to make it work even better," said Jordi Cabana, associate professor of chemistry at UIC and co-corresponding author of the paper.
As a battery charges and discharges, its electrodes – the materials where the reactions that produce energy take place – are alternately oxidized and reduced. The chemical pathways by which these reactions take place help to determine how quickly a battery becomes depleted.
Tools currently available for studying these reactions can only provide information on the average composition of electrodes at any given point in time. For example, they can let a researcher know what percentage of the electrode has become permanently oxidized. But these tools cannot provide information on the location of oxidized portions in the electrode. Because of these limitations, researchers could not tell if reactions were confined to a certain area of the electrode, such as the surface of the material, or if reactions were taking place uniformly throughout the electrode.
"Being able to tell if there is a tendency for a reaction to take place in a specific part of the electrode, and better yet, the location of reactions within individual nanoparticles in the electrode, would be extremely useful because then you could understand how those localized reactions correlate with the behavior of the battery, such as its charging time or the number of recharge cycles it can undergo efficiently," Cabana said.
The new technique, called X-ray ptychographic tomography, came about through a partnership between chemists at UIC and scientists at the Advanced Light Source at Lawrence Berkeley National Laboratory. Advanced Light Source scientists developed the instrumentation and measurement algorithms, which were used to help answer fundamental questions about battery materials and behavior identified by the UIC team.
Together, the two teams used the tomographic technique to look at tens of nanoparticles of lithium-iron phosphate recovered from a battery electrode that had been partially charged. The researchers used a coherent, nanoscale beam of X-rays generated by the high-flux synchrotron accelerator at the Advanced Light Source to interrogate each nanoparticle. The pattern of absorption of the beam by the material gave the researchers information about the oxidation state of iron in the nanoparticles.
Because they were able to move the beam by just a few nanometers and run their interrogation again, the team could reconstruct chemical maps of the nanoparticles with a resolution of about 11nm. By rotating the material in space, they could create a three-dimensional tomographic reconstruction of the oxidation states of each nanoparticle. In other words, they could tell the extent to which each individual nanoparticle of lithium iron phosphate had reacted.
"Using our new technique, we could not only see that individual nanoparticles showed different extents of reaction at a given time, but also how the reaction worked its way through the interior of each nanoparticle," Cabana said.
Life depends on keeping things flowing. Blood in our veins, nutrients in our digestive tracts, or air in our lungs, all need to be kept moving. When disease or damage obstruct the flow, medical stents and scaffolds can save lives. They hold crucial arteries open, while these blood vessels repair themselves, or maintain the necessary structure of a damaged esophagus or intestine.
Despite their benefits and widespread use, existing stents can promote damaging inflammation, may become the site of further blockage due to sluggish flow, or can break in situ. Each clinical condition and each patient also ideally requires a customized stent or scaffolding graft with a specific size, shape, and strength.
"The need for improved manufacturing techniques and materials to create personalized medical devices to improve the outcome of medical procedures," was the stimulus leading to the development of the new technique, Ameer explains. The researchers explored recent developments in 3D printing techniques, allowing a liquid citric acid-based polymer to be printed into a versatile range of solid and biodegradable 3D structures. They overcame some initial difficulties by designing a new printer. They call their technique Micro-Continuous Liquid Interface Production (microCLIP).
"We were very surprised by how well the microCLIP concept was able to rapidly produce a device with excellent properties," says Ameer. "By marrying the new materials and the high-resolution 3D printing process, it is possible to tailor the stent to address an individual patient’s needs, all at high fabrication speed and precision," adds Sun. The procedure created very thin but strong scaffolding structures that should minimize the disturbances to blood flow and be able to fit inside very small blood vessels. The stent struts can now be made as thin as a human hair.
The work to date has created stents that perform well in tests designed to simulate the chemical and mechanical conditions of their likely operating environment. These trials include examining the interaction of the material with cultured cells.
The next stage will be to test the materials in live animals and then move on toward clinical trials. "We hope to work closely with industry to bring our materials to the market," says Ameer.
It's hard to believe that a single material can be described by as many superlatives as graphene can. Since its discovery in 2004, scientists have found that the lacy, honeycomb-like sheet of carbon atoms is not just the thinnest material known in the world, but also incredibly light and flexible, hundreds of times stronger than steel, and more electrically conductive than copper.
Now, physicists at Massachusetts Institute of Technology (MIT) and Harvard University have found the wonder material can exhibit even more curious electronic properties. In two papers published today in Nature, the team reports it can tune graphene to behave at two electrical extremes. The first paper describes tuning graphene to behave as an insulator, in which electrons are completely blocked from flowing; the second paper describes tuning graphene to behave as a superconductor, in which electrical current can stream through without resistance.
Researchers in the past, including this team, have been able to make graphene superconducting by placing the material in contact with other superconducting metals – an arrangement that allows graphene to inherit some superconducting behaviors. This time around, the team found a way to make graphene superconduct on its own, demonstrating that superconductivity can be an intrinsic quality in this purely carbon-based material.
The physicists accomplished this by creating a ‘superlattice’ of two graphene sheets stacked together – not precisely on top of each other, but rotated ever so slightly, at a ‘magic angle’ of 1.1°. As a result, the overlaying, hexagonal honeycomb pattern is offset slightly, creating a precise moiré configuration that is predicted to induce strange, ‘strongly correlated interactions’ between the electrons in the graphene sheets. In any other stacked configuration, graphene prefers to remain distinct, interacting very little, electronically or otherwise, with its neighboring layers.
The team, led by Pablo Jarillo-Herrero, an associate professor of physics at MIT, found that when rotated at the magic angle, the two sheets of graphene exhibit non-conducting behavior, similar to an exotic class of materials known as Mott insulators. When the researchers then applied voltage, adding small amounts of electrons to the graphene superlattice, they found that, at a certain level, the electrons broke out of the initial insulating state and flowed without resistance, as if through a superconductor.
"We can now use graphene as a new platform for investigating unconventional superconductivity," Jarillo-Herrero says. "One can also imagine making a superconducting transistor out of graphene, which you can switch on and off, from superconducting to insulating. That opens many possibilities for quantum devices."
A material's ability to conduct electricity is normally represented in terms of energy bands. A single band represents a range of energies that a material's electrons can have. There is an energy gap between bands, and when one band is filled, an electron must embody extra energy to overcome this gap, in order to occupy the next empty band.
A material is considered an insulator if the last occupied energy band is completely filled with electrons. Electrical conductors such as metals, on the other hand, exhibit partially filled energy bands, with empty energy states which the electrons can fill to move freely.
Mott insulators are a class of materials that appear from their band structure to conduct electricity; when measured, however, they behave as insulators. Specifically, their energy bands are half-filled, but because of strong electrostatic interactions between electrons (as charges of equal sign repel each other), the material does not conduct electricity. The half-filled band essentially splits into two miniature, almost-flat, bands, with electrons completely occupying one band and leaving the other empty, causing the material to behave as an insulator.
"This means all the electrons are blocked, so it's an insulator because of this strong repulsion between the electrons, so nothing can flow," Jarillo-Herrero explains. "Why are Mott insulators important? It turns out the parent compound of most high-temperature superconductors is a Mott insulator."
In other words, scientists have found ways to manipulate the electronic properties of Mott insulators to turn them into superconductors, at relatively high temperatures of about 100K. To do this, they chemically ‘dope’ the material with oxygen, because oxygen atoms attract electrons out of the Mott insulator, leaving more room for the remaining electrons to flow. When enough oxygen is added, the insulator morphs into a superconductor. How exactly this transition occurs, Jarillo-Herrero says, has been a 30-year mystery.
"This is a problem that is 30 years and counting, unsolved," Jarillo-Herrero says. "These high-temperature superconductors have been studied to death, and they have many interesting behaviors. But we don't know how to explain them."
Jarillo-Herrero and his colleagues looked for a simpler platform to study such unconventional physics. In studying the electronic properties of graphene, the team began to play around with simple stacks of graphene sheets. The researchers created two-sheet superlattices by first exfoliating a single flake of graphene from graphite, then carefully picking up half the flake using a glass slide coated with a sticky polymer and an insulating material of boron nitride.
They then rotated the glass slide very slightly and picked up the second half of the graphene flake, adhering it to the first half. In this way, they created a superlattice with an offset pattern that is distinct from graphene's original honeycomb lattice.
The team repeated this experiment, creating several ‘devices’, or graphene superlattices, with various angles of rotation, between 0° and 3°. They attached electrodes to each device and measured an electrical current passing through, then plotted the device's resistance, given the amount of the original current that passed through.
"If you are off in your rotation angle by 0.2°, all the physics is gone," Jarillo-Herrero says. "No superconductivity or Mott insulator appears. So you have to be very precise with the alignment angle."
At 1.1° – a rotation that has been predicted to be a ‘magic angle’ – the researchers found the graphene superlattice electronically resembled a flat band structure, similar to a Mott insulator, in which all electrons carry the same energy regardless of their momentum.
"Imagine the momentum for a car is mass times velocity," Jarillo-Herrero says. "If you're driving at 30 miles per hour, you have a certain amount of kinetic energy. If you drive at 60 miles per hour, you have much higher energy, and if you crash, you could deform a much bigger object. This thing is saying, no matter if you go 30 or 60 or 100 miles per hour, they would all have the same energy."
For electrons, this means that, even if they are occupying a half-filled energy band, one electron does not have any more energy than any other electron, to enable it to move around in that band. Therefore, even though such a half-filled band structure should act like a conductor, it instead behaves as an insulator – and more precisely, a Mott insulator.
This gave the team an idea: What if they could add electrons to these Mott-like superlattices, similar to how scientists doped Mott insulators with oxygen to turn them into superconductors? Would graphene assume superconducting qualities in turn?
To find out, they applied a small gate voltage to the ‘magic-angle graphene superlattice’, adding small amounts of electrons to the structure. As a result, individual electrons bound together with other electrons in graphene, allowing them to flow where before they could not. Throughout, the researchers continued to measure the electrical resistance of the material and found that when they added a certain small number of electrons, the electrical current flowed without dissipating energy – just like a superconductor.
"You can flow current for free, no energy wasted, and this is showing graphene can be a superconductor," Jarillo-Herrero says.
Perhaps more importantly, he says the researchers are able to tune graphene to behave as an insulator or a superconductor, and any phase in between, exhibiting all these diverse properties in one single device. This is in contrast to other methods, in which scientists have had to grow and manipulate hundreds of individual crystals, each of which can be made to behave in just one electronic phase.
"Usually, you have to grow different classes of materials to explore each phase," Jarillo-Herrero says. "We're doing this in-situ, in one shot, in a purely carbon device. We can explore all those physics in one device electrically, rather than having to make hundreds of devices. It couldn't get any simpler."
This story is adapted from material from MIT, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Fundacja na rzecz Nauki Polskiej ogłosiła wyniki programu First Team, w którym przyznawane są granty na stworzenie pierwszych zespołów badawczych. Wśród laureatów znalazł się dr inż. Grzegorz Soboń z Wydziału Elektroniki Politechniki Wrocławskiej
ASTM International is running a seminar on sustainability on 11 April 2018, San Diego, California, USA.
The committee on copper and copper alloys is sponsoring the Seminar on the Update on Activities and Directions of the E60 Sustainability Committee.
Carrie Claytor, director of health, environment and sustainable development with the Copper Development Association (CDA) will be presenting on the organization of the International committee. There will also be a discussion regarding the overlap of the committee on sustainability with interested of the committee on copper.
Sabic has released the results of a recent lifecycle assessment of passenger car side doors using hybrid material solutions including laminates made with its continuous fiber-reinforced thermoplastic composite (CFRTC), the UDMAX GPP 45-70 tape.
The company says that material system has been conceived to help improve compliance with stringent energy and emissions regulations.
The life cycle assessment (LCA) found that doors made with the glass fiber polypropylene-reinforced composites outperformed metal car doors with regards to global warming potential and cumulative energy demand. The CFRTC parts weigh less than steel, aluminum and magnesium and deliver improved strength, corrosion resistance and the ability to be produced in high volumes using injection molding.
The assessment, performed in compliance with ISO 14040/44, compared a side door of a passenger car (a typical sedan) made with thermoplastic matrix composites comprising of UDMAX GPP 45-70 tape combined with an injection-molded grade of glass-filled thermoplastic resin, to identical doors made of steel, aluminum and magnesium. The UDMAX tapes were converted into a laminate and then overmolded onto both sides of a substrate using Sabic’s STAMAX glass reinforced polypropylene product, creating a hybrid material system. Parameters for vehicle operation were based on three powertrains – internal combustion (no adaptation), plug-in hybrid and electric – operating over a lifetime of 200,000 km using the New European Driving Cycle.
The results for the internal combustion powertrain showed that the thermoplastic composite doors achieved lower global warming potential than any of the three metal doors: 26% lower than steel, 21% lower than aluminum and 37% lower than magnesium. These numbers were slightly different for the hybrid and electric powertrains.
For cumulative energy demand, the thermoplastic composite doors also achieved lower numbers than the metal doors: 10% less than steel, 13% less than aluminum and 26% less than magnesium for the internal combustion powertrain. Again, the results were slightly different for the hybrid and electric powertrains.
‘Many countries, including China, Japan and several across the European Union, have announced they will tighten vehicle emissions regulations in the near future,’ said Scott Fallon, global automotive leader, Sabic. ‘These impending changes add urgency to the need for advanced new material solutions that can reduce part weight without sacrificing performance.’
This story uses material from Sabic,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
ELG Carbon Fibre, which specialises in recycled carbon fiber materials, has announced plans to increase the capacity of its UK facility.
It will focus on increasing its capacity to recover fiber from uncured prepreg and laminate feedstock and the commercialisation of the company’s Carbiso MB product line for reinforced thermoplastic compounds.
ELG’s existing UK facility currently houses highly reclamation and conversion equipment that supports the manufacture of recycled carbon fiber products to be reintroduced into the supply chain.
In 2016, to promote the use of recycled carbon in the composites industry, ELG installed a custom built, nonwoven production line to make carbon fiber and hybrid thermoplastic mats in aerial weights from 100-500 gsm and widths up to 2.7 m. These products are currently being used in production automotive programs.
ELG is also upgrading its pyrolysis furnace to increase its output capacity beyond the current 1,000 tonnes of carbon fiber per year. This upgrade will be completed in the fourth quarter of 2018, after which the company says it will be able to deliver 1,700 tonnes of carbon fiber products to its customers from the Coseley plant each year.
‘We are very focused on investments that offer customers a viable, high volume alternative to costly virgin carbon fiber,’ said Frazer Barnes, managing director ELG Carbon.
This story uses material from ELG,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The Fraunhofer Institute for Laser Technology ILT has developed an inline system for testing, qualifying and adjusting the focused powder jet of the nozzles of laser metal deposition machines. With this system, nozzles can be certified and the caustic characterized, the organization says. The user can also visualize and monitor the process.
According to Fraunhofer, the success of laser material deposition depends on how evenly the laser beam applies the powder since it is difficult to adjust the process parameters, such as the speed and volume of the powder feed into the melt pool. Before the process, nozzles and caustics must, therefore, be regularly checked, certified and calibrated. However, the sequence of these steps can be complex and cumbersome.
As a result the engineers at Fraunhofer have developed a machine-supported inline process consisting of three main components: a camera module along with movable optics and illumination, all of which are mounted on the machining head. The nozzle is measured with a laser module, which is placed in the system. The control of these two modules is provided by electronics integrated either in a separate or the machine control cabinet.
In order to detect and measure the particle density distribution and caustics of the powder jet, the jet is illuminated with a laser line perpendicular to the powder gas flow and observed by the coaxially arranged camera through the powder nozzle. The system changes the relative position of the laser and the machining head several times for further measurements. Finally, the evaluation of 2,000 to 3,000 images shows the statistical distribution of the particles in one plane. ‘If I use this method to gradually capture the so-called caustics – i.e. the focusing area in which the powder particle beam is bundled – it can be calculated and characterized very precisely in terms of the most important parameters, such as the minimum diameter and the density distribution, said graduate engineer Oliver Nottrodt, project manager for process control and system technology at Fraunhofer ILT.
This story uses material from Fraunhofer,with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Są jak średniowieczni mnisi – ich zadaniem jest „przepisywanie ksiąg”. Zamiast jednak posługiwać się gęsim piórem, mają do dyspozycji ultranowoczesny, superszybki komputer. Pracownicy PWr digitalizują tysiące archiwalnych materiałów filmowych