Noul design de celule de combustie alimentat de nanocristale învelite în grafen (New fuel cell design powered by graphene-wrapped nanocrystals)

au elaborat o rețetă de materiale noi pentru o baterie Hidrogenul de combustibil – care înconjoară nanocristalele de magneziu absorbante de hidrogen cu foi grafenice atomice subțiri – pentru a-și împinge performanțele înainte în zonele cheie.Aceste cristale de magneziu încapsulate cu grafeni acționează ca „bureți” pentru hidrogen, oferind o modalitate foarte compactă și sigură de a lua și de a stoca hidrogen. Nanocristalele permit, de asemenea, o alimentare mai rapidă și reduce dimensiunea totală a rezervorului.

Posted: Mar 11, 2016

New fuel cell design powered by graphene-wrapped nanocrystals

(Nanowerk News) Hydrogen is the lightest and most plentiful element on Earth and in our universe. So it shouldn’t be a big surprise that scientists are pursuing hydrogen as a clean, carbon-free, virtually limitless energy source for cars and for a range of other uses, from portable generators to telecommunications towers–with water as the only byproduct of combustion.While there remain scientific challenges to making hydrogen-based energy sources more competitive with current automotive propulsion systems and other energy technologies, researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a new materials recipe for a battery-like hydrogen fuel cell–which surrounds hydrogen-absorbing magnesium nanocrystals with atomically thin graphene sheets–to push its performance forward in key areas.The graphene shields the nanocrystals from oxygen and moisture and contaminants, while tiny, natural holes allow the smaller hydrogen molecules to pass through. This filtering process overcomes common problems degrading the performance of metal hydrides for hydrogen storage. Illustration of Graphene Sheets and Magnesium Nanocrystal Thin sheets of graphene oxide (red sheets) have natural, atomic-scale defects that allow hydrogen gas molecules to pass through while blocking larger molecules such as oxygen (O2) and water (H2O). Berkeley Lab researchers encapsulated nanoscale magnesium crystals (yellow) with graphene oxide sheets to produce a new formula for metal hydride fuel cells. (Image: Jeong Yun Kim)These graphene-encapsulated magnesium crystals act as „sponges” for hydrogen, offering a very compact and safe way to take in and store hydrogen. The nanocrystals also permit faster fueling, and reduce the overall „tank” size.”Among metal hydride-based materials for hydrogen storage for fuel-cell vehicle applications, our materials have good performance in terms of capacity, reversibility, kinetics and stability,” said Eun Seon Cho, a postdoctoral researcher at Berkeley Lab and lead author of a study related to the new fuel cell formula, published recently in Nature Communications („Graphene oxide/metal nanocrystal multilaminates as the atomic limit for safe and selective hydrogen storage”).In a hydrogen fuel cell-powered vehicle using these materials, known as a „metal hydride” (hydrogen bound with a metal) fuel cell, hydrogen gas pumped into a vehicle would be chemically absorbed by the magnesium nanocrystaline powder and rendered safe at low pressures.Jeff Urban, a Berkeley Lab staff scientist and co-author, said, „This work suggests the possibility of practical hydrogen storage and use in the future. I believe that these materials represent a generally applicable approach to stabilizing reactive materials while still harnessing their unique activity–concepts that could have wide-ranging applications for batteries, catalysis, and energetic materials.”The research, conducted at Berkeley Lab’s Molecular Foundry and Advanced Light Source, is part of a National Lab Consortium, dubbed HyMARC (Hydrogen Materials–Advanced Research Consortium) that seeks safer and more cost-effective hydrogen storage, and Urban is Berkeley Lab’s lead scientist for that effort.The U.S. market share for all electric-drive vehicles in 2015, including full-electric, hybrids and plug-in hybrid vehicles, was 2.87 percent, which amounts to about 500,000 electric-drive vehicles out of total vehicle sales of about 17.4 million, according to statistics reported by the Electric Drive Transportation Association, a trade association promoting electric-drive vehicles.Hydrogen-fuel-cell vehicles haven’t yet made major in-roads in vehicle sales, though several major auto manufacturers including Toyota, Honda, and General Motors, have invested in developing hydrogen fuel-cell vehicles. Indeed, Toyota released a small-production model called the Mirai, which uses compressed-hydrogen tanks, last year in the U.S.A potential advantage for hydrogen-fuel-cell vehicles, in addition to their reduced environmental impact over standard-fuel vehicles, is the high specific energy of hydrogen, which means that hydrogen fuel cells can potentially take up less weight than other battery systems and fuel sources while yielding more electrical energy.A measure of the energy storage capacity per weight of hydrogen fuel cells, known as the „gravimetric energy density,” is roughly three times that of gasoline. Urban noted that this important property, if effectively used, could extend the total vehicle range of hydrogen-based transportation, and extend the time between refueling for many other applications, too.More R&D is needed to realize higher-capacity hydrogen storage for long-range vehicle applications that exceed the performance of existing electric-vehicle batteries, Cho said, and other applications may be better suited for hydrogen fuel cells in the short term, such as stationary power sources, forklifts and airport vehicles, portable power sources like laptop battery chargers, portable lighting, water and sewage pumps and emergency services equipment.Cho said that a roadblock to metal hydride storage has been a relatively slow rate in taking in (absorption) and giving out (desorption) hydrogen during the cycling of the units. In fuel cells, separate chemical reactions involving hydrogen and oxygen produce a flow of electrons that are channeled as electric current, creating water as a byproduct.The tiny size of the graphene-encapsulated nanocrystals created at Berkeley Lab, which measure only about 3-4 nanometers, or billionths of a meter across, is a key in the new fuel cell materials’ fast capture and release of hydrogen, Cho said, as they have more surface area available for reactions than the same material would at larger sizes.Another key is protecting the magnesium from exposure to air, which would render it unusable for the fuel cell, she added.Working at The Molecular Foundry, researchers found a simple, scalable and cost-effective „one pan” technique to mix up the graphene sheets and magnesium oxide nanocrystals in the same batch. They later studied the coated nanocrystals’ structure using X-rays at Berkeley Lab’s Advanced Light Source. The X-ray studies showed how hydrogen gas pumped into the fuel cell mixture reacted with the magnesium nanocrystals to form a more stable molecule called magnesium hydride while locking out oxygen from reaching the magnesium.”It is stable in air, which is important,” Cho said.Next steps in the research will focus on using different types of catalysts–which can improve the speed and efficiency of chemical reactions–to further improve the fuel cell’s conversion of electrical current, and in studying whether different types of material can also improve the fuel cell’s overall capacity, Cho said.
Source: Lawrence Berkeley National Laboratory
Read more: New fuel cell design powered by graphene-wrapped nanocrystals

Nano-materiale noi funcționalizate pentru captarea dioxidului de carbon ( Novel functionalized nanomaterials for carbon dioxide capture )

au creat noi nanomateriale funcționale care permit o încărcare mai mare a aminei, cu o scădere minimă a suprafeței.Nanosilice nostru fibros (KCC-1) ar trebui să fie un bun candidat pentru a fi utilizat ca suport pentru a proiecta eficient de CO 2 sorbenți , care ar permite o mai bună capacitate de captare, cinetică și recylability“, spune Dr. Vivek Polshettiwar, stiinta de plumb al acestui studiu. O caracteristică unică a KCC-1 este suprafața sa mare, care provine din morfologia sa fibroasă și nu din canalele sale mezoporoase (spre deosebire de alte materiale bine studiate cum ar fi SBA-15 sau MCM-41).

Posted: May 09, 2016
Novel functionalized nanomaterials for carbon dioxide capture (Nanowerk News) Climate change due to excessive CO2 levels is one of the most serious problems mankind has ever faced. This has resulted in abrupt weather patterns such as flood and drought, which are extremely disruptive and detrimental to life, as we have been witnessing in India in recent years. Mitigating rising CO2 levels is of prime importance. In a new development, scientists at the Tata Institute of Fundamental Research, Mumbai, have developed a novel design of CO2 sorbents that show superior CO2 capture capacity and stability over conventional materials.
The immobilization of functional amines on a porous solid support can result in stable and efficient CO2 sorbent materials compared to similar liquid sorbents. A critical disadvantage however, is a drastic decrease in the textural properties of these supports (i.e., their surface area and pore volume), leading to a decrease in the CO2 capture capability.
To overcome this challenge, scientists at TIFR Mumbai, have designed novel functionalised nanomaterials that allows higher amine loading with a minimal decrease in surface area.
2 Capture” border=”0″ align=”middle”>
Novel functionalized nanomaterials for CO2 capture. (© RSC)
„Our fibrous nanosilica (KCC-1) should be a good candidate for use as a support to design efficient CO2 sorbents that would allow better capture capacity, kinetics and recylability”, says Dr Vivek Polshettiwar, the lead scientist of this study. A unique feature of KCC-1 is its high surface area, which originates from its fibrous morphology and not from its mesoporous channels (unlike in other well studied materials like SBA-15 or MCM-41).
This study, published recently in the Journal of Materials Chemistry A („Design of CO2 sorbents using functionalized fibrous nanosilica (KCC-1): insights into the effect of the silica morphology (KCC-1 vs. MCM-41)”), demonstrates the usefulness of the fibrous morphology of KCC-1 compared to conventional ordered mesoporous silica. This work is in continuation of the teams efforts to develop sustainable catalysts and sorbents.
The KCC-1-based sorbents showed several advantages over conventional silica-based sorbents, including i) high amine loading, ii) minimum reduction in surface area after functionalization and iii) more accessibility of the amine sites to enhance CO2 capture efficiency (i.e., capture capacity, kinetics and recyclability), due to the fibrous structure and high accessible surface area of KCC-1.
The demand for such efficient sorbents is on the rise since CO2 capture is one of the best solutions to mitigate the rising levels of CO2. Solid sorbents exhibit better efficiency with greater potential to overcome the shortcomings of liquid sorbents.
The use of mesoporous silica materials functionalized with various amino groups is well reported. Although materials like SBA-15 and MCM-41, for example, have attracted significant attention because their large pore sizes can accommodate a variety of amine molecules and the high surface area allows for a higher loading of these functional molecules, they suffer from the disadvantages of a decrease in textural properties, thus making KCC-1 a suitable candidate for more efficient CO2 capture.

Source: Tata Institute of Fundamental Research

Schimbarea culorii fotonilor unici într-o memorie cuantică de diamante (Changing the color of single photons in a diamond quantum memory)

au transformat pentru prima data culoarea si lățimea de banda a fotonilor ultra-rapizi folosind o memorie cuantica la temperatura camerei diamant.
Schimbarea culorii unui foton sau schimbarea frecvenței acestuia este necesară pentru a conecta în mod optim componentele dintr-o rețea cuantică. De exemplu, în comunicarea cuantică optică, cea mai bună transmisie printr-o fibră optică este apropiată de infraroșu, dar mulți dintre senzorii care le măsoară funcționează mult mai bine pentru lumina vizibilă, care este o frecvență mai mare. Posibilitatea de a schimba culoarea fotonului între fibră și senzor permite o funcționare mai performantă, inclusiv rate mai mari ale datelor.

Posted: Apr 05, 2016
Changing the color of single photons in a diamond quantum memory (Nanowerk News) Researchers from the Institute for Quantum Computing at the University of Waterloo and the National Research Council of Canada (NRC) have, for the first time, converted the colour and bandwidth of ultrafast single photons using a room-temperature quantum memory in diamond.
Shifting the colour of a photon, or changing its frequency, is necessary to optimally link components in a quantum network. For example, in optical quantum communication, the best transmission through an optical fibre is near infrared, but many of the sensors that measure them work much better for visible light, which is a higher frequency. Being able to shift the colour of the photon between the fibre and the sensor enables higher performance operation, including bigger data rates.

This is an artist’s impression of quantum frequency conversion in a diamond quantum memory. Researchers from the Institute for Quantum Computing at the University of Waterloo and the National Research Council of Canada (NRC) have, for the first time, converted the colour and bandwidth of ultrafast single photons using a room-temperature quantum memory in diamond. (Image: Dr. Khabat Heshami, National Research Council Canada)
The research, published in Nature Communications („Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory”), demonstrated small frequency shifts that are useful for a communication protocol known as wavelength division multiplexing. This is used today when a sender needs to transmit large amounts of information through a transmission so the signal is broken into smaller packets of slightly different frequencies and sent through together. The information is then organized at the other end based on those frequencies.
In the experiments conducted at NRC, the researchers demonstrated the conversion of both the frequency and bandwidth of single photons using a room-temperature diamond quantum memory.
„Originally there was this thought that you just stop the photon, store it for a little while and get it back out. The fact that we can manipulate it at the same time is exciting,” said Kent Fisher a PhD student at the Institute for Quantum Computing and with the Department of Physics and Astronomy at Waterloo. „These findings could open the door for other uses of quantum memory as well.”
The diamond quantum memory works by converting the photon into a particular vibration of the carbon atoms in the diamond, called a phonon. This conversion works for many different colours of light allowing for the manipulation of a broad spectrum of light. The energy structure of diamond allows for this to occur at room temperature with very low noise. Researchers used strong laser pulses to store and retrieve the photon. By controlling the colours of these laser pulses, researchers controlled the colour of the retrieved photon.
„The fragility of quantum systems means that you are always working against the clock,” remarked Duncan England, researcher at NRC. „The interesting step that we’ve shown here is that by using extremely short pulses of light, we are able to beat the clock and maintain quantum performance.”
The integrated platform for photon storage and spectral conversion could be used for frequency multiplexing in quantum communication, as well as build up a very large entangled state – something called a cluster state. Researchers are interested in exploiting cluster states as the resource for quantum computing driven entirely by measurements.
„Canada is a power-house in quantum research and technology. This work is another example of what partners across the country can achieve when leveraging their joint expertise to build next-generation technologies,” noted Ben Sussman, program leader for NRC’s Quantum Photonics program.

Source: University of Waterloo

Hexapod rapid, de înaltă încărcare pentru simulare de mișcare, stabilizare și anulare

Noul HEXAPODAL compact este de călătorie liniară variază de până la 200mm și rotația la 66 de grade. Acesta este condus de brushless servomotoare și combină o capacitate de încărcare mare (130 lbs), cu răspuns rapid și viteze liniare mari de până la 80mm / sec și viteza unghiulară de 30 ° / sec. Paralel Designul cinematicii elimina necesitatea cablurilor și a rezultatelor se deplasează într-o soluție de poziționare foarte rigid și compact, în comparație cu convenționale modele multi-axe.

Posted: Apr 29, 2016
Fast, High-Load Hexapod for Motion Simulation, Stabilization, and Cancellation
(Nanowerk News) PI (Physik Instrumente) LP, a leading manufacturer of precision positioning, motion control and nanopositioning equipment, introduces the H-900KSCO hexapod, designed dynamic motion in XYZ, pitch roll, and yaw. 6-axis parallel kinematics motion is perfected by PI hexapods delivering nanopositioning precision, high speed, and stability necessary to meet today’s demanding motion control applications.

H-900KSCO hexapod
Applications of H-900KSCO Hexapod
Hexapod applications include motion simulation (profiles compatible to ISO 20672, ISO 8728, and ISO 16328), industrial production, precision machining, automotive industry, stabilization of motion on moving vehicles and vessels.
Compact & Stiff, No Moving Cables
The new compact hexapod provides linear travel ranges up to 200mm and rotation to 66 degrees. It is driven by brushless servo-motors and combines high load capacity (130 lbs) with fast response and high linear speeds up to 80mm/sec and angular speed of 30°/sec. The parallel kinematics design eliminates the need for moving cables and results in a very stiff and compact positioning solution, compared to conventional multi-axis designs.

Watch video on versatility of PI Hexapods
Specifications, Datasheet, More Information
Standard and Custom
PI has in-house engineered solutions with over 4 decades of experience working with customers to provide products that meet application demands, and can quickly modify existing product designs or provide a fully customized OEM part to fit the exact requirements of the application.
Features & Advantages
Low-Wear, Brushless DC Motor Load Up to 60kg Travel Ranges to 200mm (linear), 66° (rotation) Speed: 80mm/sec (linear), 30°/sec (angular)
About PI
PI is a leading manufacturer of precision motion control equipment, piezo motors, air bearing stages and hexapod parallel-kinematics for semiconductor applications, photonics, bio-nano-technology and medical engineering. PI has been developing and manufacturing standard & custom precision products with piezoceramic and electromagnetic drives for 4 decades. The company has been ISO 9001 certified since 1994 and provides innovative, high-quality solutions for OEM and research. PI is present worldwide with eleven subsidiaries, R&D / engineering on 3 continents and total staff of 850.

Source: PI (press release)

Explorarea fosforului, un material nou promitator

În cercetarea lor, care apare în ACS Nano Letters („anizotropică Electron-foton si Electron-fonon Interactions in Black Fosfor“), echipa a stabilit initial pentru a rafina o tehnică existentă pentru minerit determinist orientarea cristalului. Această tehnică, care profită de spectroscopie Raman, foloseste un laser pentru măsurarea vibrațiilor atomului în cristal ca energia se mișcă prin ea, cauzate de interacțiunea electron-fononice. Ca și alte interacțiuni, interacțiunile electron-fononice în interiorul cristalelor de atom-gros de fosfor negru sunt anizotrope și, odată măsurate, au fost folosite pentru a prezice orientarea cristalului.

Posted: Apr 29, 2016
Exploring phosphorene, a promising new material (Nanowerk News) Two-dimensional phosphane, a material known as phosphorene, has potential application as a material for semiconducting transistors in ever faster and more powerful computers. But there’s a hitch. Many of the useful properties of this material, like its ability to conduct electrons, are anisotropic, meaning they vary depending on the orientation of the crystal.
Now, a team including researchers at Rensselaer Polytechnic Institute (RPI) has developed a new method to quickly and accurately determine that orientation using the interactions between light and electrons within phosphorene and other atoms-thick crystals of black phosphorus. Phosphorene–a single layer of phosphorous atoms–was isolated for the first time in 2014, allowing physicists to begin exploring its properties experimentally and theoretically. Vincent Meunier, head of the Rensselaer Department of Physics, Applied Physics, and Astronomy and a leader of the team that developed the new method, published his first paper on the material–confirming the structure of phosphorene–in that same year.

Phosphorene. (Image: Matthew Cherny)
„This is a really interesting material because, depending on which direction you do things, you have completely different properties,” said Meunier, a member of the Rensselaer Center for Materials, Devices, and Integrated Systems (cMDIS). „But because it’s such a new material, it’s essential that we begin to understand and predict its intrinsic properties.”
Meunier and researchers at Rensselaer contributed to the theoretical modeling and prediction of the properties of phosphorene, drawing on the Rensselaer supercomputer, the Center for Computational Innovations (CCI), to perform calculations. Through the Rensselaer cMDIS, Meunier and his team are able to develop the potential of new materials such as phosphorene to serve in future generations of computers and other devices. Meunier’s research exemplifies the work being done at The New Polytechnic, addressing difficult and complex global challenges, the need for interdisciplinary and true collaboration, and the use of the latest tools and technologies, many of which are developed at Rensselaer.
In their research, which appears in ACS Nano Letters („Anisotropic Electron-Photon and Electron-Phonon Interactions in Black Phosphorus”), the team initially set out to refine an existing technique for determining the orientation of the crystal. This technique, which takes advantage of Raman spectroscopy, uses a laser to measure vibrations of the atoms within the crystal as energy moves through it, caused by electron-phonon interactions. Like other interactions, electron-phonon interactions within atoms-thick crystals of black phosphorus are anisotropic and, once measured, have been used to predict the orientation of the crystal.
In reviewing their initial results from Raman spectroscopy, the team noticed several inconsistencies. To investigate further, they obtained actual images of the orientation of their sample crystals using Transmission Electron Microscopy (TEM), and then compared them with the Raman spectroscopy results. As a topographic technique, TEM offers a definitive determination of the orientation of the crystal, but isn’t as easy to obtain as the Raman results. The comparison revealed that electron-phonon interactions alone did not accurately predict the orientation of the crystal. And the reason why led the way to yet another anisotropy of phosphorene–that of interactions between photons of light and electrons in the crystal.
„In Raman you use a laser to impart energy into the material, and it starts to vibrate in ways that are intrinsic to the material, and which, in phosphorene, are anisotropic,” said Meunier. „But it turns out that if you shine the light in different directions, you get different results, because the interaction between the light and the electrons in the material–the electron-photon interaction–is also anisotropic, but in a non-commensurate way.”
Meunier said the team had reason to believe phosphorene was anisotropic with respect to electron-photon interactions, but didn’t anticipate the importance of the property.
„Usually electron-photon anisotropy doesn’t make such a big difference, but here, because we have such a particular chemistry on the surface and such a strong anisotropy, it’s one of those materials where it makes a huge difference,” Meunier said.
Although the discovery revealed a flaw in the interpretations of Raman spectra relying on electron-phonon interactions, it also revealed that electron-photon interactions alone provide an accurate determination of the orientation of the crystal.
„It turns out that it’s not so easy to use Raman vibrations to find out the direction of the crystal,” Meunier said. „But, and this is the beautiful thing, what we found is that the electron-photon interaction (which can be measured by recording the amount of light absorbed)–the interaction between the electrons and the laser–is a good predictor of the direction. Now you can really predict how the material will behave as a function of excitement with an outside stimulus.”

Source: Rensselaer Polytechnic Institute

Oamenii de stiinta prezic o noua familie de materiale promitatoare pentru racirea in stare solida

Fizicienii Daniel Errandonea, al Institutului UV de Știința Materialelor (ICMUV), și Claudio Cazorla, de la Scoala de Stiinta si Ingineria Materialelor, Universitatea din New South Wales (Australia), tocmai au prezis făcut ion de materiale care efectuează: cum ar fi fluorină (CaF2) ar putea prezenta un efect mai mare mecano-caloric decât chiar grupul feroelectrice. În această lumină, conductorii de ioni apar ca o nouă familie de materiale cu aplicații promițătoare în răcire în stare solidă. Și vestea bună este, a făcut fluorita este foarte abundent în natură, cu depozite în multe țări, inclusiv Spania.
Mai în detaliu, studiul stabilește relația dintre tensiunea mecanică externă și de transport ionic în conductoarele de ioni utilizând dinamica moleculară (o metodă de simulare pe computer pentru studierea mișcărilor fizice ale atomilor și moleculelor) și calculele mecanicii cuantice.

Posted: Apr 29, 2016
Scientists predict promising new family of materials for solid-state cooling (Nanowerk News) In a new paper published in Nano Letters („Giant Mechanocaloric Effects in Fluorite-Structured Superionic Materials”), scientists from the University of Valencia point to a new family of materials with promising applications in solid-state cooling.
Scientists have long been using solid-state cooling methods as an alternative to conventional refrigeration techniques that rely on pollutant gases. However, the efficiency of solid-state cooling has typically left much to be desired, being up to four times less efficient than conventional methods. Until now the required mechano-caloric effects have only been observed in ferroelectric materials and superelastic metal alloys, both of which are very scarce and very costly.
But the search for more efficient materials might be over. Physicists Daniel Errandonea, of the UV’s Institute of Material Science (ICMUV), and Claudio Cazorla, of the School of Materials Science and Engineering, University of New South Wales (Australia), have just predicted that ion conducting materials such as fluorite (CaF2) might present a greater mechano-caloric effect than even the ferroelectric group. In this light, ion conductors emerge as a new family of materials with promising applications in solid-state cooling. And the good news is, that fluorite is very abundant in nature, with deposits in many countries including Spain.
In more detail, the study establishes the relationship between external mechanical tension and ionic transport in ion conductors using molecular dynamics (a computer simulation method for studying the physical movements of atoms and molecules) and quantum mechanics calculations.
The work shows that applying pressure to the material serves as an efficient means of adjusting critical temperature in superionic compounds (fast ion conductors).
These results, published in Nanoletters in April 2016, pave the way for a rational design of green cooling technologies that are not only more ecological, but more efficient and cost-effective than conventional cooling methods. They also have important implications for the development of solid-state batteries.

Source: RUVID

Noua tehnică prezintă mișcări active în celule(New technique spots active motion in cells)

Orice sistem în echilibru termodinamic este cunoscut pentru a satisface tranzițiile perfect echilibrate înainte și înapoi între oricare două state. Este deci imposibil, de exemplu, de a conduce o moară de vânt pentru a face de lucru prin utilizarea numai fluctuațiile termice. Noi cercetari arata modul în care sistemele de viață încalcă acest principiu. Astfel, chiar și fluctuațiile stocastice în căutarea sistemelor vii ar putea fi folosite pentru a conduce căutarea o moară de vânt la scară mică.
Acum, oamenii de stiinta de la MIT, Universitatea din Gottingen, Ludwig Maximilians Universitatea din Munchen, Universitatea Amsterdam liber, și Universitatea Yale au dezvoltat o tehnica de analiză a datelor neinvaziv a facut poate discerne daca al obiectului de mișcare aleatoare este condus în mod activ sau termic. După urmărirea conformații sau locațiile au o structură în interiorul celulei sau o particulă trece prin așa cum se mișcă, și observând modul în care particula tranzițiile înainte și înapoi între statele de căutare, cercetatorii aplica un principiu fundamental al fizicii statistice la mina determinist Fie mișcările aleatorii activ sau Therma

Posted: Apr 29, 2016
New technique spots active motion in cells (Nanowerk News) Inside every living cell, internal structures are continuously moving about. Under a microscope, organelles such as the nucleus, mitochondria, transport vesicles, or even external flagella wobble and twitch. This may happen spontaneously as these tiny structures are passively jostled inside a cell. But that’s not necessarily all there is to it. Often a cell invests extra energy into these motions to enhance cell functions in ways we don’t yet understand.
At the microscopic scale, particles in a fluid or a gas can move about in response to bombardment by the surrounding molecules. Such passive, thermally-induced motions are often very hard to distinguish from actively driven movements, and it can be impossible to tell just by looking whether particular motions inside a cell are simply thermal or pushed by some extra input of energy.

Any system in thermodynamic equilibrium is known to satisfy perfectly balanced forward and backward transitions between any two states. It is therefore impossible, for instance, to drive a windmill to do work by using only thermal fluctuations. The new research shows how living systems violate this principle. Thus, even stochastic fluctuations in such living systems could be used to drive such a small-scale windmill.
Now scientists at MIT, the University of Göttingen, Ludwig Maximilians University of Munich, the Free University Amsterdam, and Yale University have developed a noninvasive data analysis technique that can discern whether an object’s random motion is actively or thermally driven. After tracking the conformations or locations that a structure within the cell or a particle passes through as it moves, and observing how the particle transitions back and forth between such states, the researchers apply a fundamental principle of statistical physics to determine whether the random motions are active or thermal.
Nikta Fakhri, assistant professor in MIT’s Department of Physics, says the results will help scientists to uncover “hidden” active processes that drive a cell’s constituents to move in seemingly random ways.
“We want to see if particular dynamics in living systems — be those cells or tissues or whole organisms — that look at first glance like random thermal motion are indeed actively driven,” says Fakhri, who is a first co-author on the paper. “This is important because there must be a vital function connected with the process if the cell spends energy on it. Our work provides a practical experimental method to identify active, nonequilibrium processes in observations of biological systems.”
Fakhri and her colleagues have published their results today in the journal Science („Nikta Fakhri”).

Researchers at MIT and elsewhere have developed a noninvasive technique that distinguishes active from passive fluctuations inside cells. (Video: Melanie Gonick/MIT)
Shaking things up
Observations of the movements of microscopic particles date back to 1827, when Scottish botanist Robert Brown was looking through a microscope at pollen grains in water. He noticed that the grains contained tiny particles that jiggled vigorously, and at first glance believed that their motion meant the particles were somehow alive and moving on their own. Eventually, Brown retired this theory when he observed the same jiggling with inert particles from rocks, realizing that just seeing a particle moving doesn’t necessarily mean it is alive.
Scientists now know that such particles are being pushed around by even smaller water molecules, which themselves are jiggling. At elevated temperatures, water molecules possess kinetic energy and can remain forever restless. At microscopic scales, these tiny molecules and atoms can “bombard” other much larger particles. This phenomenon is now known as Brownian motion. Scientists today are so used to seeing Brownian motion that they often assume that a particle moving in a random fashion is likely to be at thermal equilibrium — a state in which a system is not dissipating any energy, and therefore inanimate.
In living cells, of course, many organelles or particles tend to move in a “ballistic” fashion, traveling across some distance, with a clearly directed or oscillatory trajectory. These types of motions, Fakhri says, represent an animated state that must be out of equilibrium, requiring a system to expend energy. What is interesting, however, are situations where particles jiggle randomly and seem to be in equilibrium, but in reality move actively.
Frame by frame
Fakhri and her colleagues set out to develop a statistical physics technique that would enable them to tell, just by imaging a particle, whether its random motions are thermal or active in nature.
Using video microscopy, they studied, frame by frame, the oscillatory motion of the flagellum of a Chlamydomonas algae. They deconstructed the backbone of the flagellum into a series of shapes, thus creating a phase space of the states the flagellum passes through as it completes an oscillatory cycle. They then counted the transitions between states. In thermal equilibrium, the back-and-forth transitions between all states must be balanced. However, they observed a clear imbalance in these transitions, confirming the already known fact that the flagellum expends energy for this active oscillatory motion.
Next, they analyzed the motions of a kidney cell’s cilium — an antenna-like appendage that at first glance appears to be jiggling back and forth passively. By tracking the cilium’s orientation and curvature, and counting transitions between states, they observed a slight imbalance in the transitions, pointing to an unexpected active process that drives the cilium, despite its passive appearance.
“This is a great paper, and somewhat a proof of principle,” says Gavin Crooks, senior scientist at Lawrence Berkeley National Laboratory. “Their method has the potential to be applicable to lots of cellular processes — we’ll get deeper insights into the flow of information and energy through the cell, and what makes these molecule machines tick. You could imagine using these methods to examine if a piece of cellular machinery is working the way that it’s meant to.”
Fakhri says the new method will help scientists to uncover new ways in which cells dissipate energy — which, ultimately, is the key to sustaining life. After all, as the Austrian physicist Erwin Schrödinger noted, “Living matter evades the decay to thermal equilibrium.”
“Almost a century later, through the work of this collaboration, we can now go further and find out how cells budget their energy and particularly why they often expend a lot of energy to create these apparently random motions,” Fakhri says.

Source: By Jennifer Chu, MIT

Filmul de răcire pe bază de grafen, aproape de producția la scară pilot

metodă eficientă de răcire a electronicii prin utilizarea nanoflacilor grafeni funcționali

Posted: Apr 29, 2016
Cooling graphene-based film close to pilot-scale production (Nanowerk News) Heat dissipation in electronics and optoelectronics is a severe bottleneck in the further development of systems in these fields. To come to grips with this serious issue, researchers at Chalmers University of Technology have developed an efficient way of cooling electronics by using functionalized graphene nanoflakes. The results will be published in the renowned journal Nature Communications(„Functionalization mediates heat transport in graphene nanoflakes”).

Functionalization mediates heat transport of graphene nanoflakes. (Image: Johan Liu, credit: Philip Krantz, Krantz Nanoart)
„Essentially, we have found a golden key with which to achieve efficient heat transport in electronics and other power devices by using graphene nanoflake-based film. This can open up potential uses of this kind of film in broad areas, and we are getting closer to pilot-scale production based on this discovery,” says Johan Liu, Professor of Electronics Production at Chalmers University of Technology in Sweden.
The researchers studied the heat transfer enhancement of the film with different functionalized amino-based and azide-based silane molecules, and found that the heat transfer efficiency of the film can be improved by over 76 percent by introducing functionalization molecules, compared to a reference system without the functional layer. This is mainly because the contact resistance was drastically reduced by introducing the functionalization molecules.
Meanwhile, molecular dynamic simulations and ab initio calculations reveal that the functional layer constrains the cross-plane scattering of low-frequency phonons, which in turn enhances in-plane heat-conduction of the bonded film by recovering the long flexural phonon lifetime. The results suggested potential thermal management solutions for electronic devices.
In the research, scientists studied a number of molecules that were immobilized at the interfaces and at the edge of graphene nanoflake-based sheets forming covalent bonds. They also probed interface thermal resistance by using a photo-thermal reflectance measurement technique to demonstrate an improved thermal coupling due to functionalization.
„This is the first time that such systematic research has been done. The present work is much more extensive than previously published results from several involved partners, and it covers more functionalization molecules and also more extensive direct evidence of the thermal contact resistance measurement,” says Johan Liu.

Source: Chalmers University of Technology

Ce este un lichid cu spin quant?

Caracterul evaziv lichide cuantice spin, face foarte dificil de a confirma existența lor și să identifice natura exactă a acestora. Prezența unui lichid cuantic de spin poate fi dedusă dintr-o lipsă de aliniere a rotirilor de electroni, dar confirmarea finală este complicat: absența probelor nu constituie o dovadă a absenței, deoarece zicale. O abordare mai sofisticată este de a descoperi mai multe caracteristici distinctive și unice ale lichidului cuantic de spin pentru a permite o confirmare pozitivă

Posted: Apr 29, 2016
What is a quantum spin liquid? (Nanowerk News) Magnetism is one of the oldest recognised material properties. Known since antiquity, records from the 3rd century BC describe how lodestone, a naturally occurring magnetised ore of iron, was used in primitive magnetic compasses. Today, thanks to the theory of quantum mechanics we now understand the nature of magnetism, too, with the concept of spin explaining the behaviour of elementary particles such as electrons in the material that make it magnetic.
Spin, a property of sub-atomic particles such as electrons and quarks, makes each individual electron behave as if it were a tiny magnetic compass needle. The millions or billions of electron spins in a piece of material interact with each other in various ways and stabilise to form the different possible magnetic states found in solid matter. Taken together in such large numbers, the spin of the material’s electrons grants the same magnetic properties to the material itself.
Magnetism is essential for the basic trappings of modernity: magnetic materials form the basis of modern electronics and information storage. With this in mind, scientists have pursued the discovery of materials with entirely new magnetic behaviours or new states of matter with unprecedented and potentially beneficial properties.
One is that of a quantum spin liquid (New Journal of Physics, „Focus on Quantum Spin Liquids”), first proposed by the Nobel Prize-winning theoretical physicist PW Anderson in the early 1970s. In a paper published in the journal Nature Materials („Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet”), a research team led by Professor Stephen Nagler at the Oak Ridge National Laboratory in the US has demonstrated the quantum spin liquid nature of the magnetic material ruthenium trichloride (α-RuCl3).
How do quantum spin liquids form?
Quantum spin liquids are frequently found in a class of materials known as frustrated magnets. In a conventional magnet, the interactions between spins result in stable formations, known as their long-range order, in which the magnetic directions of each individual electron is aligned.
Herbertsmithite, a candidate quantum spin liquid source. (Image: Rob Lavinsky/iRocks.com, CC BY-SA)In a frustrated magnet, the arrangement of electron spins prevents them from forming an ordered alignment, and so they collapse into a fluctuating, liquid-like state. In a true quantum spin liquid, the electron spins never align, and continue to fluctuate even at the very lowest temperatures of absolute zero, at which the spins in other magnetic states of matter would have already frozen.The conditions required for a quantum spin liquid to form are often found in nature. The most famous example is the copper-based mineral Herbertsmithite, for which there is significant evidence to suggest that a quantum spin liquid state exists within the frustrated magnetic layers of copper ions that make up its structure. Where do we find quantum spin liquids? A challenge for scientists is to recreate the conditions required to synthetically grow candidate quantum spin liquid materials in the laboratory to allow for a complete understanding of their properties.
Quantum spin liquids’ evasive character make it notoriously difficult to confirm their existence and pinpoint their exact nature. The presence of a quantum spin liquid can be inferred from a lack of alignment of electron spins, but definitive confirmation is tricky: absence of evidence is not evidence of absence, as the adage goes. A more sophisticated approach is to uncover the more distinctive and unique characteristics of the quantum spin liquid to allow for a positive confirmation.
This is why Nagler’s study is particularly noteworthy. In experiments using neutron spectroscopy, the team revealed that α-RuCl3 realises something extremely close to a special flavour of quantum spin liquid called a Kitaev spin liquid. A prerequisite for this particular quantum spin liquid state is that the spins of the magnetic ruthenium ions form a frustrated honeycomb network: a layered, two-dimensional hexagonal structure, similar to that assumed by carbon atoms in graphite.
In their experiment, a beam of neutron particles created by a particle accelerator was scattered from the sample of α-RuCl3 transferring energy between the neutrons and the sample in the process. This energy transfer was quantified by a set of detectors surrounding the sample, and the response observed fits that described by the theory developed for the Kitaev quantum spin liquid in particular.
What can we do with quantum spin liquids?
We now recognise that the quantum spin liquid comes in several different varieties with subtly different properties, but that they all share the ability to support peculiar quantum mechanical phenomena. This is exciting, and not just from a purely scientific perspective: these states could be used in the development of quantum computers and other transformative quantum technologies that are expected to provide revolutionary changes to how we process and store data throughout the 21st century.
In the age of quantum computing, we will be able to perform calculations that are currently unsolvable on even the most powerful supercomputers of today. This will allow for breakthroughs in a vast array of fields in which we are tackling some of the biggest challenges of our time, from drug discovery to the design of smarter materials for a whole host of applications. As we discover more candidate quantum state liquid materials and better understand their behaviour, we will unravel ever more exotic physics and discover ways to manipulate and control this novel state of matter to our advantage.

Source: By Lucy Clark, Research Fellow, University of St Andrews, via The Conversation

Spintronics pentru tehnologiile informaționale viitoare

Tehnologiile informaționale viitoare shoulderstand folosesc în mod considerabil mai puțină energie pentru procesarea datelor. O clasă de materiale interesante pentru acest izolatori topologice cuprinde. Izolatori topologice se disting prin electronii lor la suprafata fiind extrem de mobil, în timp ce materialul este în vrac într-un izolator și nu se efectuează. Deci, din moment ce electronii Simultan transporta un moment magnetic (rotire), izolatori topologice s-ar putea face, prin urmare componente „spintronice“ fezabilă. Componentele spintronice nu ar trebui să se bazeze pe mișcarea purtătorilor de sarcină cum ar fi electroni (ca în componente semiconductoare), ci pe transportul sau manipularea lor rotiri. Acest lucru ar necesita considerabil mai puțină energie.

Posted: Apr 29, 2016
Spintronics for future information technologies (Nanowerk News) Researchers have demonstrated that this class of materials is suitable for data processing based on spin. The work has been published in the renowned periodical Physical Review B and was selected as „Editor’s Suggestion” article („Ultrafast spin-polarization control of Dirac fermions in topological insulators”).

The illustration depicts the characteristic spin orientation (arrows) of electrons in a topological insulator (below). Using an initial circular polarised laser pulse, the spins are excited and point up or down. This can be proven by a second linearly polarised laser pulse (above). (Image: HZB)
Future information technologies should employ considerably less energy for processing data. One exciting class of materials for this comprises topological insulators. Topological insulators are distinguished by their electrons at the surface being extremely mobile, while the bulk material within is an insulator and does not conduct. Since electrons also simultaneously carry a magnetic moment (spin), topological insulators might also make „spintronic” components feasible. Spintronic components would not be based on the movement of charge carriers like electrons (as in semiconductor components), but instead on the transport or manipulation of their spins. This would require considerably less energy.
An international team headed by HZB physicist Jaime Sánchez-Barriga has now shown how the spins of the electrons in topological insulators can be controlled. The team investigated samples of antimony-telluride, a topological insulator, using circularly polarised laser light. They were able to initiate and direct currents of electrons whose spins were oriented in parallel (i. e., spin-polarised currents) using the „rotational direction” of the laser light. In addition, they were successful in changing the orientation of the spins as well. The team was made up of experimentalists from the Max Born Institute in Berlin and Lomonossow University Moscow, together with theoreticians from Ludwig-Maximilians-Universität München (LMU).
„If you were to utilise magnetically doped topological insulators, you could also probably store this spin information”, explains Oliver Rader, who heads the research group for green spintronics at HZB. „To investigate this however, and also be able to explore the dynamic behaviour of the magnetic moments in particular, ultra-short light pulses in the soft X-ray region are needed. These kinds of experiments can become standard with the planned upgrade of the BESSY II synchrotron source to BESSY-VSR”, he hopes.

Source: Helmholtz-Zentrum Berlin für Materialien und Energie

Materiale compozite din nanotuburi din nanoparticule de argilă pentru ingineria țesuturilor

Chitosan, un biopolimer biodegradabil și chimic versatil naturale, a fost utilizat în mod eficient în antibacteriene, antifungice, anti-tumoral și formula țiilor imunostimulatoare. Pentru a depăși dezavantajele schelelor chitosan pure, cum ar fi: fragilitate mecanică și rezistența biologică scăzută, schele de chitosan sunt în mod tipic dopate cu alți compuși de sprijin care să permită consolidarea mecanică, rezultând astfel compozit schele rezistente biologic.
Agaroza este o polizaharidă coloana vertebrală pe bază de galactoză izolată din alge roșii, având proprietăți mecanice remarcabile, care sunt utile în proiectarea schelelor de inginerie tisulară.
Gelatina este FORMEAZĂ de colagen prin hidroliza (ruperea structurii triplu-helix în molecule cu o singură plajă) și are o serie de avantaje față de precursorul său. Este mai puțin imunogenă Comparativ cu colagen și MENȚINEREA informațional secvențe semnal promo adeziune celulară ting, migrația, diferențierea și proliferarea.
Neregulile suprafeței porilor schele din cauza

Posted: Apr 29, 2016
Clay nanotube-biopolymer composite scaffolds for tissue engineering (Nanowerk News) The fabrication of a prototype tissue having functional properties close to the natural ones is crucial for effective transplantation. Tissue engineering scaffolds are typically used as supports which allow cells to form tissue-like structures essentially required for the correct functioning of the cells under the conditions close to the three-dimensional tissue.
Scientists of Bionanotechnology Lab, Kazan Federal University, combined three biopolymers, chitosan and agarose (polysaccharides), and a protein gelatine, as the materials to produce tissue engineering scaffolds and demonstrated the enhancement of mechanical strength (doubled pick load), higher water uptake and thermal properties in chitosan-gelatine-agarose hydrogels doped with halloysite (Nanoscale, „Clay nanotube–biopolymer composite scaffolds for tissue engineering”).

A sketch demonstrating the fabrication and in vitro and in vivo testing of novel halloysite-doped biopolymer tissue engineering scaffold. (Image: Bionanotechnology Lab, Institute of Fundamental Medicine and Biology, Kazan Federal University)
Chitosan, a natural biodegradable and chemically versatile biopolymer, has been effectively used in antibacterial, antifungal, anti-tumour and immunostimulating formulations. To overcome the disadvantages of pure chitosan scaffolds such as mechanical fragility and low biological resistance, chitosan scaffolds are typically doped with other supporting compounds which allow for mechanical strengthening, thus yielding composite biologically resistant scaffolds.
Agarose is a galactose-based backbone polysaccharide isolated from red algae, having remarkable mechanical properties which are useful in the design of tissue engineering scaffolds.
Gelatine is formed from collagen by hydrolysis (breaking the triple-helix structure into single-strand molecules) and has a number of advantages over its precursor. It is less immunogenic compared with collagen and it retains informational signal sequences promoting cell adhesion, migration, differentiation and proliferation.
The surface irregularities of the scaffold pores due to the insoluble nanosized components promote the best adhesion of the cells on scaffold materials, while the nanoparticle fillers increase the composites’ strength. Thus, researchers doped halloysite nanotubes into a chitosan-agarose-gelatine matrix to design the implantable 3D cell scaffolds.
The resulting scaffolds demonstrate the shape memory upon deformation and have the porous structure suitable for cell adhesion and proliferation which is essential for artificial tissue fabrication. Macroscopic observations have confirmed that all the samples of scaffolds exhibited the sponge-like behaviour with the shape memory and shape reconstitution after deformation both in wet and dry states.
The swelling experiments indicated that the addition of halloysite can greatly improve the hydrophilicity and wetting of composite scaffolds. The incorporation of halloysite nanotubes into the scaffolds increases the water uptake and subsequently improves the biocompatibility. The intrinsic properties of halloysite nanotubes can be used for further improving the biocompatibility of scaffolds by the loading and sustained release of different bioactive compounds. This opens the prospect for fabrication of scaffolds with defined properties for directed differentiation of cells on matrixes due to gradual release of differentiation factors.
Experiments on two types of human cancer cells (A549 and Hep3B) show that in vitro cell adhesion and proliferation on the nanocomposites occur without changes in viability and cytoskeleton formation.
Further in vivo biocompatibility and biodegradability evaluation in rats has confirmed that the scaffolds promote the formation of novel blood vessels around the implantation sites. The scaffolds show excellent resorption within six weeks after implantation in rats. Neo-vascularization observed in newly formed connective tissue placed near the scaffold allows for the complete restoration of blood flow.
The results obtained indicate that the halloysite doped scaffolds are biocompatible as demonstrated both in vitro and in vivo. In addition, they confirm the great potential of chitosan-agarose-gelatine nanocomposite porous scaffolds doped with halloysite in tissue engineering with potential for sustained nanotube drug delivery.

Source: Kazan Federal University

New fuel cell design powered by graphene-wrapped nanocrystals

Novel functionalized nanomaterials for carbon dioxide capture

Changing the color of single photons in a diamond quantum memory

Fast, High-Load Hexapod for Motion Simulation, Stabilization, and Cancellation

Exploring phosphorene, a promising new material

Scientists predict promising new family of materials for solid-state cooling

New technique spots active motion in cells

Cooling graphene-based film close to pilot-scale production

What is a quantum spin liquid?

Spintronics for future information technologies

Clay nanotube-biopolymer composite scaffolds for tissue engineering