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.
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.
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.”
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
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.
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.
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.
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
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
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.
Ele pot fi depozitate direct pe materiale ca straturi subtiri facut sunt de 50 de ori mai subtire decat un fir de păr uman, astfel încât nu este nevoie să producă siliciu«napolitana»celule și să le interconecta separat“, a adăugat el. „Ei, de asemenea, să răspundă mai bine decât siliciu la lungimi de unda albastru de lumină, și pot fi stivuite ca un film subțire pe partea de sus a celulelor de siliciu pentru a îmbunătăți performanța generală În cele din urmă.“
Prin posibilitatea de a depozita celule solare CZTS pe diverse suprafețe, echipa Hao cred că acest lucru le pune ferm pe drumul de a face celule fotovoltaice thin-film facut poate fi rigid sau flexibil și durabil și suficient de ieftine pentru a fi integrate pe scară largă în clădiri pentru a genera energie electrică de greve lumina soarelui au structuri, cum ar fi: geamuri, fațade, țigle și ferestre.
Posted: Apr 28, 2016
At last: Non-toxic and cheap thin-film solar cells for zero-energy buildings
(Nanowerk News) ‘Zero-energy’ buildings – which generate as much power as they consume – are now much closer after a team at Australia’s University of New South Wales achieved the world’s highest efficiency using flexible solar cells that are non-toxic and cheap to make.
Until now, the promise of ‘zero-energy’ buildings been held back by two hurdles: the cost of the thin-film solar cells (used in façades, roofs and windows), and the fact they’re made from scarce, and highly toxic, materials.
That’s about to change: the UNSW team, led by Dr Xiaojing Hao of the Australian Centre for Advanced Photovoltaics at the UNSW School of Photovoltaic and Renewable Energy Engineering, have achieved the world’s highest efficiency rating for a full-sized thin-film solar cell using a competing thin-film technology, known as CZTS.
The new high-efficiency, low-toxicity solar cells developed by UNSW’s Australian Centre for Advanced Photovoltaics. (Image: Robert Largent/UNSW)
NREL, the USA’s National Renewable Energy Laboratory, confirmed this world leading 7.6% efficiency in a 1cm2 area CZTS cell this month.
Unlike its thin-film competitors, CZTS cells are made from abundant materials: copper, zinc, tin and sulphur.
And CZTS has none of the toxicity problems of its two thin-film rivals, known as CdTe (cadmium-telluride) and CIGS (copper-indium-gallium-selenide). Cadmium and selenium are toxic at even tiny doses, while tellurium and indium are extremely rare.
„This is the first step on CZTS’s road to beyond 20% efficiency, and marks a milestone in its journey from the lab to commercial product,” said Hao, named one of UNSW’s 20 rising stars last year. „There is still a lot of work needed to catch up with CdTe and CIGS, in both efficiency and cell size, but we are well on the way.”
„In addition to its elements being more commonplace and environmentally benign, we’re interested in these higher bandgap CZTS cells for two reasons,” said Professor Martin Green, a mentor of Dr Hao and a global pioneer of photovoltaic research stretching back 40 years.
„They can be deposited directly onto materials as thin layers that are 50 times thinner than a human hair, so there’s no need to manufacture silicon ‘wafer’ cells and interconnect them separately,” he added. „They also respond better than silicon to blue wavelengths of light, and can be stacked as a thin-film on top of silicon cells to ultimately improve the overall performance.”
By being able to deposit CZTS solar cells on various surfaces, Hao’s team believe this puts them firmly on the road to making thin-film photovoltaic cells that can be rigid or flexible, and durable and cheap enough to be widely integrated into buildings to generate electricity from the sunlight that strikes structures such as glazing, façades, roof tiles and windows.
However, because CZTS is cheaper – and easier to bring from lab to commercialisation than other thin-film solar cells, given already available commercialised manufacturing method – applications are likely even sooner. UNSW is collaborating with a number of large companies keen to develop applications well before it reaches 20% efficiency – probably, Hao says, within the next few years.
„I’m quietly confident we can overcome the technical challenges to further boosting the efficiency of CZTS cells, because there are a lot of tricks we’ve learned over the past 30 years in boosting CdTe and CIGS and even silicon cells, but which haven’t been applied to CZTS,” said Hao.
Currently, thin-film photovoltaic cells like CdTe are used mainly in large solar power farms, as the cadmium toxicity makes them unsuitable for residential systems, while CIGS cells is more commonly used in Japan on rooftops.
First Solar, a US$5 billion behemoth that specialises in large-scale photovoltaic systems, relies entirely on CdTe; while CIGS is the preferred technology of China’s Hanergy, the world’s largest thin-film solar power company.
Thin-film technologies such as CdTe and CIGS are also attractive because they are physically flexible, which increases the number of potential applications, such as curved surfaces, roofing membranes, or transparent and translucent structures like windows and skylights.
But their toxicity has made the construction industry – mindful of its history with asbestos – wary of using them. Scarcity of the elements also renders them unattractive, as price spikes are likely as demand rises. Despite this, the global market for so-called Building-Integrated Photovoltaics (BIPV) is already valued at US$1.6 billion.
Hao believes CZTS’s cheapness, benign environmental profile and abundant elements may be the trigger that finally brings architects and builders onboard to using thin-film solar panels more widely in buildings.
Until now, most architects have used conventional solar panels made from crystalline silicon. While these are even cheaper than CZTS cells, they don’t offer the same flexibility for curved surfaces and other awkward geometries needed to easily integrate into building designs.
fotodetector cu infraroșu cu infraroșu cu infraroșu cu trei culori, cu undă scurtă. Cu noul design, dispozitivele pot detecta diferite benzi de frecvență în infraroșu prin simpla variație a tensiunii aplicate. Acest lucru ar putea deschide o gamă largă de aplicații potențiale, inclusiv televizoare color infraroșu și imagini în infraroșu cu trei culori.
„Un dispozitiv capabil să detecteze diferite valuri de infraroșu este foarte de dorit în sistemele de imagistică infraroșie de nouă generație
Posted: Apr 22, 2016
Research team realizes 3-color photodetector
(Nanowerk News) While infrared waves are available in short, mid, and long lengths, most detection devices are unable to harness all three at the same time.
Now Northwestern University’s Manijeh Razeghi and her team have developed a new approach in device design to realize a three-color, shortwave-midwave-longwave infrared photodetector. With the new design, the devices can detect different infrared wavebands by simply varying the applied bias voltage. This could open up a range of potential applications, including infrared color televisions and three-color infrared imaging.
„A device capable of detecting different infrared wavebands is highly desirable in the next generation infrared imaging systems,” said Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science in Northwestern’s McCormick School of Engineering.
Led by Razeghi, the researchers invented and investigated the new design for three-color photodiodes without using additional terminal contacts. The resulting photodetector is based on indium-arsenide/gallium-antimonide/aluminum-antimonide type-II superlattices.
As the applied bias voltage varies, the photodetector sequentially exhibits the behavior of three different colors, corresponding to the bandgap of three absorbers, and achieves well-defined cut-off wavelengths and high-quantum efficiency in each channel.
This new research builds on the Razeghi group’s many years of work in Northwestern’s Center for Quantum Devices, including the development of the first single-color, short-wavelength infrared photodetector and two-color, shortwave-midwave infrared photodetector based on type-II superlattices.
„I am fascinated by these results,” Razeghi said. „The initial success in this demonstration will drive us to the new frontier of infrared detection and imaging technology.”
