Lab descoperă aliaj de titan-aur, care este mai greu de legat de cele mai multe oțeluri(Lab discovers titanium-gold alloy that is four ties harder than most steels)

Titanul este materialul principal pentru articulațiile artificiale de genunchi și șold, deoarece este puternic, rezistent la uzură și netoxic, însă o descoperire neașteptată de către fizicienii Universității Rice arată că standardul de aur pentru articulațiile artificiale poate fi îmbunătățit prin adăugarea unor aur real

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Material non-compozit utilizat pentru dispozitivul de cloak practic(Nonocomposite material used for practical cloaking device)

au făcut ca un obiect să dispară prin utilizarea unui material compozit cu pericole de dimensiuni nanometrice care pot spori proprietățile specifice pe suprafața obiectului;While the research might not lead to the invisibility cloak made famous JK novels quite yet, this practical demonstration could result in a step-change in how antennas are tethered to their platform

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Cipul de țesut pe bază de mătase oferă promisiuni pentru testarea medicamentelor și dispozitive implantabile(Silk-based tissue chip provides promise for drug testing and implantable devices)

Gelurile de mătase au fost, de asemenea, capabile să reziste la o varietate de medii (cum ar fi modificări ale pH-ului lichidului înconjurător sau salinității) fără a modifica dimensiunea sau forma lor. Pe de altă parte, rigiditatea gelului ar putea fi manipulată pentru a se potrivi cu proprietățile țesutului țintă (mai greu pentru cartilaje, dar moale pentru piele sau creier, de exemplu). Gelurile au fost de asemenea clare, permițând o analiză mai ușoară.

Posted: Jul 12, 2016
Silk-based tissue chip provides promise for drug testing and implantable devices (Nanowerk News) Researchers have created a new type of tissue chip that can better represent human tissues compared with current chips, and can be more widely used for drug testing. By engineering the chips as a silk gel, the researchers circumvented many of the problems with existing devices. The new chip also has the potential to someday be an implantable treatment itself.
Tissue chips are collections of cells that mimic both the anatomy and physiology of a tissue or organ, making it possible to test treatments in the lab more accurately than using cells grown in a single layer in a dish. To engineer a tissue outside the body, the cells need a three-dimensional structure on which to grow. Such scaffolds are often made of polydimethylsiloxane (PDMS), a silicon-based polymer, and contain microfluidic chambers, representing blood vessels or respiratory tracts, running through them.

The enzyme alkaline phosphatase is injected into the silk chip and remains biologically active (yellow) as it diffuses into the silk hydrogel after five minutes (left) and 30 minutes (right). (Source: Elsevier) (click on image to enlarge)
These microfluidic systems have various advantages. Some systems are great for developing and testing treatments in the lab; some allow living cells to be embedded within them, while others can replicate a variety of tissue types (bone and bone marrow, say). Other systems have qualities that may allow them to be implanted in the body as part of the treatment itself; one such quality is the ability to eventually degrade away when no longer needed. But, none of the current biomaterials can do all of the above. PDMS is particularly problematic because it is non-degradable, and it sucks up lipids, such as fat molecules or steroid hormones. Many potential medications are lipid based, so PDMS absorbs them before their effects can be measured, making it difficult to test drugs. Additionally, an implant made of PDMS would absorb the body’s lipids, and since lipids are vital to the body’s function, a PDMS microchip can’t be implanted in humans.
To create a system that addresses all of these needs, researchers turned to silk, a naturally derived protein with unique properties that have several benefits: provide different levels of stiffness to match the target tissue; afford long-term stability in a variety of conditions yet still fully degrade over time; and offer transparency so researchers can observe biological processes like enzymatic activity.
“We know that silk is biocompatible so you can use it even inside the body, and it can be programmed to dissolve over time safely,” said Rosemarie Hunziker, Ph.D., program director for Tissue Engineering at NIBIB. “So this might even be an improved design that enables us to build little micro-tissues and make them implantable.” The silk-based system was described online on March 31, 2016 in the journal Biomaterials („Bio-functionalized silk hydrogel microfluidic systems”).
Researchers from the Department of Biomedical Engineering at Tufts University in Medford, Massachusetts developed the microfluidic device by mixing silk into a gel solution and casting it into a mold. This created a rectangular block of silk hydrogel with a three-dimensional network of channels running through it. Mechanical valves were also added to control flow through the channels; the flow could be switched on or off based on the air pressure within one of the chambers.

3D image of skin cells successfully growing in the biocompatible silk hydrogel. (Image: Siwei Zhao)
In living tissues and organs, interactions with other cells, proteins, and enzymes occur both within the tissue and on the surface of the channels. Modeling this involves embedding living cells and active enzymes within the gel while it’s made. However, the harsh conditions required to create PDMS kill and deactivate cells and enzymes. Because a silk hydrogel can be made at ambient temperatures and under relatively gentle conditions, it can include cells and enzymes within the gel and thus better replicate living tissue.
Silk gels were also able to withstand a variety of environments (such as changes to the surrounding fluid’s pH or salinity) without altering their size or shape. On the other hand, the stiffness of the gel could be manipulated to match the properties of the target tissue (harder for cartilage, but soft for skin or brain, for example). The gels were also clear, allowing for easier analysis.
While testing potential drugs is the likely first application of the silk system, David Kaplan, Ph.D., Stern Family Professor of Engineering at Tufts University and senior author of the paper, is also excited about the possibility of someday growing tissues on chips that can be put into the body. “Silk takes you to the next level because it can be implanted and fully resorbed in vivo,” said Kaplan.
And for researchers looking for a system that can be tailored to a specific need—whether it’s mechanical pumps, cell signaling, or imaging of cellular processes within the chip—this is it, said Kaplan. “Silk is pretty unique in the ability to integrate everything into one material system,” he said. “Now we can optimize systems in vitro (in cell culture) and directly translate that in vivo (within an animal) to look at tissue regeneration. I don’t know of any other system with the versatility that can do all that.”
Kaplan is known for using silk to solve biomedical engineering problems; he’s used it to make models of brain tissue and bone marrow, as part of surgical implants to heal broken bones, and as a method for keeping antibodies and vaccines stable at room temperature. “It’s pretty rare when we hit a roadblock that we can’t overcome with silk as the base material,” said Kaplan. “It’s a fairly universal material. I’m hopeful we’ve moved it out of the textile world and into the biomaterials and medical world.”
Indeed, compared to other polymers being tested, silk is well studied. “We already know a lot about how it reacts inside the body,” said Hunziker. In terms of developing silk-based tissue implants, “It’s like starting a relay race on the last lap instead of from the beginning.”

Source: National Institute of Biomedical Imaging and Bioengineering

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Tehnologia Nanocoating îmbunătățește teflonul(Nanocoating technology improves Teflon)

a inventat stratul compozit de nanoparticule PTFE în așteptare.stratul de acoperire va fi testat ca lubrifiant în rulmenții cu bile pentru motoarele electrice care sunt spălate frecvent cu soluții de curățare caustică. Produsul SurfTec este de așteptat să mărească durata de viață a rulmenților cu bile cu 50% comparativ cu rulmenții lubrifiați cu grăsime.

Posted: Jul 05, 2016

Nanocoating technology improves Teflon

(Nanowerk News) The National Science Foundation has awarded $225,000 to start-up company SurfTec LLC to commercialize its patent-pending technology invented at the University of Arkansas.SurfTec, a U of A-affiliated company at the Arkansas Research and Technology Park, will use the grant to investigate the feasibility of a novel approach that significantly improves wear resistance of polytetrafluoroethylene coatings.SurfTec co-founders Samuel Beckford (left) and Min Zou discuss their research in the Nano Mechanics and Tribology Laboratory at the University of Arkansas.Polytetrafluoroethylene (PTFE) is better known by its trademarked brand name: Teflon. SurfTec will show that its nano-coating technology – a thinner and more durable version of Teflon – will reduce friction and wear in manufacturing equipment, according to company co-founder Samuel Beckford.Beckford, as a graduate student at the U of A, invented the patent-pending PTFE nanoparticle composite coating with SurfTec co-founder Min Zou, professor of mechanical engineering.Initially, the coating will be tested as a lubricant in ball bearings for electric motors that are frequently washed with caustic cleaning solutions. SurfTec’s product is expected to increase the wear-life of ball bearings by 50 percent compared to grease-lubricated bearings.“Our research has shown that PTFE nanoparticle composite coatings have exceptionally low friction and durability,” Beckford said. “Historically, the use of Teflon in bearings has been limited due to a poor wear life and low adhesion to bearing components. Our thin, low-friction nanoparticle coating eliminates these weaknesses.”Beckford, who earned a doctorate in microelectronics-photonics from the U of A, has worked with Zou for the past six years on research related to the proposed coating technology. They have conducted the research in Zou’s Nano Mechanics and Tribology Laboratory in the College of Engineering.The Phase I grant came through NSF’s Small Business Innovation Research Program, which allows federal agencies to stimulate technological innovation in the private sector by strengthening small businesses that meet federal research and development needs. The program also is intended to increase the commercial application of federall

Putem bate mama natură la proiectarea materialelor?(Can we beat Mother Nature at materials design?)

o echipă de oameni de știință a evaluat motivele comune de design ale unei game de materiale structurale naturale și a determinat ce ar fi nevoie pentru a proiecta și a construi structuri care să imite natura

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Cercetătorii evaluează centralele electrice care convertesc toate emisiile de CO2 în nanotuburi de carbon(Researchers assess power plants that convert all of their CO2 emissions into carbon nanotubes)

CO2 capturat fie direct din atmosferă, fie dintr-o centrală de gaze naturale cu ciclu combinat, poate fi electrolizat pentru a produce gaz de oxigen și nanofibre de carbon, care pot fi apoi folosite pentru a produce o varietate de produse valoroase

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Un nou mod de a degrada materialele plastice care le transformă în combustibil(A new way to degrade plastics that turns them into fuel)

O echipă de cercetători de la Academia Chineză de Științe și Universitatea din California a găsit o modalitate de a degrada plasticul obișnuit într-un mod care să permită crearea unui combustibil din gunoi de plastic.În plus, catalizatorii sunt compatibili cu diferiți aditivi de poliolefine

A new

De ce Spiderman nu poate exista: geckos sunt limita de dimensiune pentru lipirea pe pereti(Why Spiderman can’t exist:Geckos are size linit for sticking to walls)

cele mai recente cercetări relevă de ce geckos sunt cele mai mari animale capabile să scadă zidurile verticale netede – chiar și alpiniștii mai mari ar necesita picioarele lipsite de manevră mari;iar scalarea este esențială pentru îmbunătățirea performanțelor adezivilor pe suprafețe mult mai mari

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A fost dezvoltată noua generație de absorbanți termici solizi de înaltă eficiență(New generation of high-efficiency solar thermal absorbers developed)

Structura este unul dintre primele exemple din lume ale unui absorber de metasurface cu trei straturi, folosind un strat intermediar de carbon.folosește carbonul amorf drept interstrat între filmele de aur subțiri și pelicula superioară, modelată cu o matrice periodică 2D, folosind o gravare cu fascicul de ioni concentrat.Celula va fi utilizată pentru aplicații de energie termică solară și are potențialul de a atinge temperaturi mult mai ridicate decât suprafețele negre simple, deoarece poate minimiza emisia de radiație termică.

Posted: Jun 15, 2016
New generation of high-efficiency solar thermal absorbers developed (Nanowerk News) Researchers from the Universities of Bristol and Exeter are one step closer to developing a new generation of low-cost, high-efficiency solar cells („A selective metasurface absorber with an amorphous carbon interlayer for solar thermal applications”). The structure is one of the world’s first examples of a tri-layer metasurface absorber using a carbon interlayer.

SEM view of MDM structure D at lower magnification. Inset image at higher magnification showing rounded nature of the upper patterned layer.
The system, developed by Chenglong Wang a PhD student in Professor Martin Cryan’s research group, uses amorphous carbon as an inter-layer between thin gold films with the upper film patterned with a 2D periodic array using focused ion beam etching.
The trilayer gold-carbon-gold metasurface strongly absorbs light across the solar spectrum but minimises emission of thermal radiation from the structure. The use of gold in the research is a first step towards a high temperature metasurface where gold can be replaced by other refractory metals such as tungsten or chrome.
The cell will be used for solar thermal energy applications and has the potential to reach much higher temperatures than simple black surfaces because it can minimise the emission of thermal radiation.
The metasurface has been developed as part of a joint project, led by Dr Neil Fox, between Bristol’s Department of Electrical and Electronic Engineering and Schools of Physics and Chemistry. The aim of this project is to develop diamond-based solar thermionic devices, which use sunlight to get surfaces sufficiently hot that they emit electrons directly into a vacuum. If these electrons are collected at a cooled anode, electrical energy can be produced with maximum efficiencies predicted to be much higher than is achievable using conventional silicon solar cells.
Martin Cryan, Professor of Applied Electromagnetics and Photonics in the Department of Electrical and Electronic Engineering, said: “Integrating diamond within metasurfaces is very challenging, and this paper is a first step in that direction using amorphous carbon. The next stage is to carry out high temperature testing on the structures and to attempt to reach the ~700 degrees celsius required to obtain efficient thermionic emission.”

Source: University of Bristol

Materialul pe bază de loofah ar putea oferi bateriilor cu litiu un impuls(Loofah-based material could give lithium batteries a boost)

Carbonul de burete din loofah ar putea fi un progres necesar pentru a muta aceste baterii înainte într-un mod ieftin și sustenabil, spun cercetătorii.

Posted: Jun 15, 2016
Loofah-based material could give lithium batteries a boost (Nanowerk News) Today’s mobile lifestyle depends on rechargeable lithium batteries. But to take these storage devices to the next level — to shore up the electric grid or for widespread use in vehicles, for example — they need a big boost in capacity. To get lithium batteries up to snuff for more ambitious applications, researchers report in the journal ACS Applied Materials & Interfaces(„Multifunctional Nitrogen-Doped Loofah Sponge Carbon Blocking Layer for High-Performance Rechargeable Lithium Batteries”) a new solution that involves low-cost, renewable loofah sponges.

A carbon material derived from loofah sponges could be used in the next generation of lithium batteries.
The lithium-ion batteries that power most of our devices still have some room for improvement. But some experts predict that even when these batteries are fully optimized, they still will not be able to meet the power needs for larger-scale applications, such as taking a car 500 miles on one charge. Scientists looking to go beyond lithium-ion have turned to lithium-sulfur and other options. But a major challenge to commercializing these technologies remains: The cathodes crumble over time, leading to progressively lower capacity. Shanqing Zhang, Yanglong Hou, Li-Min Liu and colleagues wanted to find a way to stabilize these alternatives.
The researchers developed a “blocking” layer of highly conductive, porous carbon derived from a loofah sponge. The loofah-derived membrane helped prevent the cathode from dissolving in lithium-sulfur, lithium-selenium and lithium-iodine batteries — and all three types performed well consistently over 500 to 5,000 cycles. The loofah sponge carbon could be the advance needed to move these batteries forward in a low-cost, sustainable way, the researchers say.

Source: American Chemical Society

Grafine pe bază de electrozi transparenți pentru OLEDS flexibile de înaltă eficiență

Ca o soluție, echipa coreeană de cercetare, care include în continuare profesorii Sung-Yool Choi (Inginerie electrică) și Taek-Soo Kim (Ingineria mecanică) a KAIST și studenții lor, a propus o nouă arhitectură a dispozitivelor care poate maximiza eficiența bazată pe grafen OLED – uri. Ei au fabricat un anod transparent într – o structură compozită în care un TiO 2 straturi , cu un indice ridicat de refracție (high n) și un strat gaură de injecție (HIL) de polimeri conductori , cu un indice de refracție scăzut (low-n) electrozi tip sandwich grafenice . Acesta este un design optic care induce o colaborare sinergică între nivelele înalte n și joase-n pentru a crește reflexia efectivă a TE. Ca rezultat, amplificarea rezonanței cavității optice este maximizată. Rezonanța cavității optice este legată de îmbunătățirea eficienței și a gamei de culori în OLED-urile. În același timp, pierderea de la polaritonul de suprafață a plasmonului (SPP), o cauză majoră pentru emisiile slabe de fotoni în OLED-uri, este de asemenea redusă datorită prezenței polimerilor cu conductivitate joasă.

Read more: Graphene-based transparent electrodes for highly efficient flexible OLEDS

Posted: Jun 03, 2016
Graphene-based transparent electrodes for highly efficient flexible OLEDS (Nanowerk News) The arrival of a thin and lightweight computer that even rolls up like a piece of paper will not be in the far distant future. Flexible organic light-emitting diodes (OLEDs), built upon a plastic substrate, have received greater attention lately for their use in next-generation displays that can be bent or rolled while still operating.
A Korean research team led by Professor Seunghyup Yoo from the School of Electrical Engineering, KAIST and Professor Tae-Woo Lee from the Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH) has developed highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE) which is placed in between titanium dioxide (TiO2) and conducting polymer layers. The research results were published online on June 2, 2016 in Nature Communications („Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes”).

This picture shows an OLED with the composite structure of TiO2/graphene/conducting polymer electrode in operation. The OLED exhibits 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency. The device prepared on a plastic substrate shown in the right remains intact and operates well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm. (Image: KAIST) (click on image to enlarge)
OLEDs are stacked in several ultra-thin layers on glass, foil, or plastic substrates, in which multi-layers of organic compounds are sandwiched between two electrodes (cathode and anode). When voltage is applied across the electrodes, electrons from the cathode and holes (positive charges) from the anode draw toward each other and meet in the emissive layer. OLEDs emit light as an electron recombines with a positive hole, releasing energy in the form of a photon. One of the electrodes in OLEDs is usually transparent, and depending on which electrode is transparent, OLEDs can either emit from the top or bottom.
In conventional bottom-emission OLEDs, an anode is transparent in order for the emitted photons to exit the device through its substrate. Indium-tin-oxide (ITO) is commonly used as a transparent anode because of its high transparency, low sheet resistance, and well-established manufacturing process. However, ITO can potentially be expensive, and moreover, is brittle, being susceptible to bending-induced formation of cracks.
Graphene, a two-dimensional thin layer of carbon atoms tightly bonded together in a hexagonal honeycomb lattice, has recently emerged as an alternative to ITO. With outstanding electrical, physical, and chemical properties, its atomic thinness leading to a high degree of flexibility and transparency makes it an ideal candidate for TEs. Nonetheless, the efficiency of graphene-based OLEDs reported to date has been, at best, about the same level of ITO-based OLEDs.
As a solution, the Korean research team, which further includes Professors Sung-Yool Choi (Electrical Engineering) and Taek-Soo Kim (Mechanical Engineering) of KAIST and their students, proposed a new device architecture that can maximize the efficiency of graphene-based OLEDs. They fabricated a transparent anode in a composite structure in which a TiO2 layer with a high refractive index (high-n) and a hole-injection layer (HIL) of conducting polymers with a low refractive index (low-n) sandwich graphene electrodes. This is an optical design that induces a synergistic collaboration between the high-n and low-n layers to increase the effective reflectance of TEs. As a result, the enhancement of the optical cavity resonance is maximized. The optical cavity resonance is related to the improvement of efficiency and color gamut in OLEDs. At the same time, the loss from surface plasmon polariton (SPP), a major cause for weak photon emissions in OLEDs, is also reduced due to the presence of the low-n conducting polymers.

This picture shows the new architecture to develop highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE). (Image: KAIST) (click on image to enlarge)
Under this approach, graphene-based OLEDs exhibit 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency, which is unprecedented in those using graphene as a TE. Furthermore, these devices remain intact and operate well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm. This is a remarkable result for OLEDs containing oxide layers such as TiO2 because oxides are typically brittle and prone to bending-induced fractures even at a relatively low strain. The research team discovered that TiO2 has a crack-deflection toughening mechanism that tends to prevent bending-induced cracks from being formed easily.
Professor Yoo said, „What’s unique and advanced about this technology, compared with previous graphene-based OLEDs, is the synergistic collaboration of high- and low-index layers that enables optical management of both resonance effect and SPP loss, leading to significant enhancement in efficiency, all with little compromise in flexibility.” He added, „Our work was the achievement of collaborative research, transcending the boundaries of different fields, through which we have often found meaningful breakthroughs.”
Professor Lee said, „We expect that our technology will pave the way to develop an OLED light source for highly flexible and wearable displays, or flexible sensors that can be attached to the human body for health monitoring, for instance.”

Source: The Korea Advanced Institute of Science and Technology (KAIST)