Lună: aprilie 2018

NG2 Defense MZLMAX Advanced Dynamics Flow) / Proiectare cu aer proaspăt (AFD / VFD) Managerul de muzzle: Dispozitiv revoluționar de mufă de pușcă maximizează amortizarea exploziilor și reducerea reculului!(NG2 Defense MZLMAX Advanced Flow Dynamics)/Vent Forward Design (AFD/VFD) Muzzle Manager: Revolutionary Rifle Muzzle Device Maximizes Blast Mitagation and Recoil Reduction)

Ca și cum nu ar fi suficiente suficienți de suprimare a presiunii zero (supape de zgomot / supresoare de sunet), Ernie Bray și grupul de apărare NG2 Defense (NEXGEN2 Defense) au proiectat și dezvoltat „primul dispozitiv de lovire multidimensională cu adevărat eficient „Numit MZLMAX AFD Muzzle Manager. Interesant … și captivant. La fel ca rezervoarele NG2 (supresoare), NG2 MZLMAX utilizează tehnologia NGD (Advanced Flow Dynamics) a tehnologiei NG2 și apoi adaugă Vent Forward Design sau VFD pentru a evacua gazele înainte. Ea devine mai bine. Conform modelului NG2, designul VFD al companiei MZLMAX „implementează principiul de gestionare a gazelor 3D” Delay, Diffuse and Direct „. MZLMAX redefinește „stadiul tehnicii” pentru gestionarea botului de arme de foc. „Sună destul de bine.

NG2 Defense MZLMAX Advanced Flow Dynamics)/Vent Forward Design (AFD/VFD) Muzzle Manager: Revolutionary Rifle Muzzle Device Maximizes Blast Mitagation and Recoil Reduction! (Video!)

Posted by: David Crane April 14, 2018

As if full-auto-rated zero-back-pressure suppressors (silencers/sound suppressors) aren’t enough, Ernie Bray and the NG2 Defense (NEXGEN2 Defense) gang have also designed and developed “the first truly effective Multi-Dimensional Muzzle Device” called the MZLMAX AFD Muzzle Manager. Interesting…and catchy. Just like the NG2 cans (suppressors), the NG2 MZLMAX utilizes NG2’s AFD (Advanced Flow Dynamics) tech, and then adds Vent Forward Design, or VFD, to vent the gases forward. It gets better. According to NG2, the MZLMAX’s VFD design “implements our 3D ‘Delay, Diffuse and Direct,’ gas management principle. The MZLMAX re-defines ‘state of the art’ for firearms muzzle management.” Sounds pretty good.

The NG2 MZLMAX AFD/VFD Muzzle Manager’s main claim to combat/tactically-relevant fame is its ability to mitigate the muzzle blast enough and direct gases forward so the shooter doesn’t injure himself or others, or damage anyting around the muzzle upon firing. “So this kinda’ does it all. It does it all in one package. Very balanced design. So, you can put it on. You’re gettin’ the flash mitigation, you’re gettin’ recoil mitigation, you’re managing and directing your blast signature, all in one unit,” says Bray.

Assuming the MZLMAX does everything Bray says it does, it’s pretty impressive.

DefenseReview (DR) got our hands on both the 5.56mm NATO (5.56x45mm NATOO)/.223 Rem. and 7.62mm NATO (7.62x51mm NATO)/. .308 Win. NG2 MZLMAX AFD/VFD Muzzle Manager tactical rifle barrel muzzle device variants at SHOT Show 2018, and it intrigued us. So, we interviewed Mr. Bray about it on camera, as well (see DR’s video below). He explains the technology better than we ever could, so have a look.

Hopefully, Defense Review can get a MZLMAX into DR writer/contributor and chief new-product tester Jeff Gurwitch’s hands in the near future, so he can run it at the range and give us his thoughts on it. If Gurwitch says it’s good to go, it’s good to go.

Psst! O galerie de șoaptă pentru lumină mărește celulele solare(Psst! A whispering gallery for light boosts solar cells)

au dezvoltat un strat nanoscala pentru celule solare , care le permite să absoarbă aproximativ 20 de procente mai mult soare decât dispozitivele neacoperite. Acoperirea, aplicată printr-o tehnică care ar putea fi încorporată în procesul de fabricație, deschide o nouă cale de dezvoltare a celulelor solare cu costuri reduse și eficiente, cu materiale abundente, regenerabile și ecologice.
Învelișul constă din mii de margele de sticlă mici, doar aproximativ o sută din lățimea părului uman. Când lumina soarelui lovește acoperirea, undele luminoase sunt direcționate în jurul barei nanometrice, similar cu modul în care undele sonore se deplasează în jurul unui perete curbat,

Posted: Apr 13, 2018

Psst! A whispering gallery for light boosts solar cells

(Nanowerk News) Trapping light with an optical version of a whispering gallery, researchers at the National Institute of Standards and Technology (NIST) have developed a nanoscale coating for solar cells that enables them to absorb about 20 percent more sunlight than uncoated devices. The coating, applied with a technique that could be incorporated into manufacturing, opens a new path for developing low-cost, high-efficiency solar cells with abundant, renewable and environmentally friendly materials.
The coating consists of thousands of tiny glass beads, only about one-hundredth the width of a human hair. When sunlight hits the coating, the light waves are steered around the nanoscale bead, similar to the way sound waves travel around a curved wall such as the dome in St. Paul’s Cathedral in London. At such curved structures, known as acoustic whispering galleries, a person standing near one part of the wall easily hears a faint sound originating at any other part of the wall.
nanoresonator coating, consisting of thousands of tiny glass beads, deposited on solar cells
Illustration shows the nanoresonator coating, consisting of thousands of tiny glass beads, deposited on solar cells. The coating enhances both the absorption of sunlight and the amount of current produced by the solar cells. (Image: K. Dill, D. Ha, G. Holland/NIST)
Whispering galleries for light were developed about a decade ago, but researchers have only recently explored their use in solar-cell coatings. In the experimental set up devised by a team including Dongheon Ha of NIST and the University of Maryland’s NanoCenter, the light captured by the nanoresonator coating eventually leaks out and is absorbed by an underlying solar cell made of gallium arsenide.
Using a laser as a light source to excite individual nanoresonators in the coating, the team found that the coated solar cells absorbed, on average, 20 percent more visible light than bare cells. The measurements also revealed that the coated cells produced about 20 percent more current.
The study is the first to demonstrate the efficiency of the coatings using precision nanoscale measurements, said Ha. “Although calculations had suggested the coatings would enhance the solar cells, we could not prove this was the case until we had developed the nanoscale measurement technologies that were needed,” he noted.
This work was described in a recent issue of Nanotechnology („Nanoscale imaging of photocurrent enhancement by resonator array photovoltaic coatings”) by Ha, collaborator Yohan Yoon of NIST and Maryland’s NanoCenter, and NIST physicist Nikolai Zhitenev.
The team also devised a rapid, less-costly method of applying the nanoresonator coating. Researchers had previously coated semiconductor material by dipping it in a tub of the nanoresonator solution. The dipping method takes time and coats both sides of the semiconductor even though only one side requires the treatment.
In the team’s method, droplets of the nanoresonator solution are placed on just one side of the solar cell. A wire-wound metal rod is then pulled across the cell, spreading out the solution and forming a coating made of closely packed nanoresonators. This is the first time that researchers have applied the rod method, used for more than a century to coat material in a factory setting, to a gallium arsenide solar cell.
“This is an inexpensive process and is compatible with mass production,” said Ha.
Source: NIST

Atomii individuali de impuritate detectabili în grafen(Individual impurity atoms detectable in graphene)

ercetatorii au creat în mod specific și a examinat panglici grafen care conțin atomi de impuritate ( Știință Avansuri , „Înlocuirea heteroatomului multiplu cu nanofibrele de grafen” ).
Aceștia au înlocuit atomii de carbon anumiți în rețeaua hexagonală cu atomi de bor și atomi de azot folosind chimia suprafeței, prin plasarea compușilor precursori organici adecvați pe o suprafață de aur. La expunerea la căldură, până la 400 ° C, panglici de grafen se formează pe suprafața aurului de la precursori, incluzând atomii de impuritate la locurile specifice.

Posted: Apr 13, 2018

Individual impurity atoms detectable in graphene

(Nanowerk News) Graphene is made of a two-dimensional layer of carbon atoms arranged in a hexagonal lattice. The strong bonds between the carbon atoms make graphene extremely stable yet flexible. It is also an excellent electrical conductor through which electricity can flow with almost no loss.
Graphene’s distinctive properties can be further expanded by incorporating impurity atoms in a process known as “doping”. The impurity atoms cause local changes of the conduction that, for example, allow graphene to be used as a tiny transistor and enable the construction of circuits.

Targeted incorporation
In a collaboration between scientists from the University of Basel and the National Institute for Material Science in Tsukuba in Japan, Kanazawa University and Kwansei Gakuin University in Japan, and Aalto University in Finland, the researchers specifically created and examined graphene ribbons containing impurity atoms (Science Advances, „Multiple heteroatom substitution to graphene nanoribbon”).
They replaced particular carbon atoms in the hexagonal lattice with boron and nitrogen atoms using surface chemistry, by placing suitable organic precursor compounds on a gold surface. Under heat exposure up to 400°C, tiny graphene ribbons formed on the gold surface from the precursors, including impurity atoms at specific sites.
Using the atomic force microscope’s carbon monoxide functionalized tip (red/silver), the forces between the tip and the various atoms in the graphene ribbon can be measured
Using the atomic force microscope’s carbon monoxide functionalized tip (red/silver), the forces between the tip and the various atoms in the graphene ribbon can be measured. (Image: University of Basel, Department of Physics)

Measuring the strength of the atoms
Scientists from the team led by Professor Ernst Meyer from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics examined these graphene ribbons using atomic force microscopy (AFM). They used a carbon monoxide functionalized tip and measured the tiny forces that act between the tip and the individual atoms.
This method allows even the smallest differences in forces to be detected. By looking at the different forces, the researchers were able to map and identify the different atoms. “The forces measured for nitrogen atoms are greater than for a carbon atom,” explains Dr. Shigeki Kawai, lead author of the study and former postdoc in Meyer’s team. “We measured the smallest forces for the boron atoms.” The different forces can be explained by the different proportion of repulsive forces, which is due to the different atomic radii.
Computer simulations confirmed the readings, proving that AFM technology is well-suited to conducting chemical analyses of impurity atoms in the promising two-dimensional carbon compounds.
Source: Universität Basel

Inteligența artificială accelerează descoperirea sticlei metalice(Artificial intelligence accelerates discovery of metallic glass)

Dacă combinați două sau trei metale împreună, veți obține un aliaj care de obicei arată și se comportă ca un metal, cu atomii săi aranjați în modele geometrice rigide.
Dar din când în când, în condițiile potrivite, veți obține ceva cu totul nou: un aliaj futurist numit sticlă metalică. Atomii materialului amorf sunt aranjați în orice fel, la fel ca atomii de sticlă dintr-o fereastră. Natura sa sticloasă o face mai puternică și mai ușoară decât cea mai bună oțel de astăzi și se ridică mai bine la coroziune și uzură.
Deși sticla metalică arată o mulțime de promisiuni ca acoperire protectoare și alternativă la oțel, doar câteva mii din milioane de combinații posibile de ingrediente au fost evaluate în ultimii 50 de ani și doar o mână a fost dezvoltată până la punctul de a deveni util.

Posted: Apr 13, 2018

Artificial intelligence accelerates discovery of metallic glass

(Nanowerk News) If you combine two or three metals together, you will get an alloy that usually looks and acts like a metal, with its atoms arranged in rigid geometric patterns.
But once in a while, under just the right conditions, you get something entirely new: a futuristic alloy called metallic glass. The amorphous material’s atoms are arranged every which way, much like the atoms of the glass in a window. Its glassy nature makes it stronger and lighter than today’s best steel, and it stands up better to corrosion and wear.
Although metallic glass shows a lot of promise as a protective coating and alternative to steel, only a few thousand of the millions of possible combinations of ingredients have been evaluated over the past 50 years, and only a handful developed to the point that they may become useful.
Now a group led by scientists at Northwestern University, the Department of Energy’s SLAC National Accelerator Laboratory and the National Institute of Standards and Technology (NIST) has reported a shortcut for discovering and improving metallic glass — and, by extension, other elusive materials — at a fraction of the time and cost.
Machine learning algorithms pinpoint new materials
With new approach, predictions closely match actual experimental data. (Image: SLAC)
The research group took advantage of a system at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) that combines machine learning — a form of artificial intelligence where computer algorithms glean knowledge from enormous amounts of data — with experiments that quickly make and screen hundreds of sample materials at a time. This allowed the team to discover three new blends of ingredients that form metallic glass, and to do it 200 times faster than it could be done before.
The study was published today, April 13, in Science Advances („Accelerated discovery of metallic glasses through iteration of machine learning and high-throughput experiments”).
“It typically takes a decade or two to get a material from discovery to commercial use,” said Chris Wolverton, the Jerome B. Cohen Professor of Materials Science and Engineering in Northwestern’s McCormick School of Engineering, who is an early pioneer in using computation and AI to predict new materials. “This is a big step in trying to squeeze that time down. You could start out with nothing more than a list of properties you want in a material and, using AI, quickly narrow the huge field of potential materials to a few good candidates.”
The ultimate goal, said Wolverton, who led the paper’s machine learning work, is to get to the point where a scientist can scan hundreds of sample materials, get almost immediate feedback from machine learning models and have another set of samples ready to test the next day — or even within the hour.
Over the past half century, scientists have investigated about 6,000 combinations of ingredients that form metallic glass. Added paper co-author Apurva Mehta, a staff scientist at SSRL: “We were able to make and screen 20,000 in a single year.”

Just getting started
While other groups have used machine learning to come up with predictions about where different kinds of metallic glass can be found, Mehta said, “The unique thing we have done is to rapidly verify our predictions with experimental measurements and then repeatedly cycle the results back into the next round of machine learning and experiments.”
There’s plenty of room to make the process even speedier, he added, and eventually automate it to take people out of the loop altogether so scientists can concentrate on other aspects of their work that require human intuition and creativity. “This will have an impact not just on synchrotron users, but on the whole materials science and chemistry community,” Mehta said.
The team said the method will be useful in all kinds of experiments, especially in searches for materials like metallic glass and catalysts whose performance is strongly influenced by the way they’re manufactured, and those where scientists don’t have theories to guide their search. With machine learning, no previous understanding is needed. The algorithms make connections and draw conclusions on their own, which can steer research in unexpected directions.
“One of the more exciting aspects of this is that we can make predictions so quickly and turn experiments around so rapidly that we can afford to investigate materials that don’t follow our normal rules of thumb about whether a material will form a glass or not,” said paper co-author Jason Hattrick-Simpers, a materials research engineer at NIST. “AI is going to shift the landscape of how materials science is done, and this is the first step.”

Experimenting with data
In the metallic glass study, the research team investigated thousands of alloys that each contain three cheap, nontoxic metals.
They started with a trove of materials data dating back more than 50 years, including the results of 6,000 experiments that searched for metallic glass. The team combed through the data with advanced machine learning algorithms developed by Wolverton and Logan Ward, a graduate student in Wolverton’s laboratory who served as co-first author of the paper.
Based on what the algorithms learned in this first round, the scientists crafted two sets of sample alloys using two different methods, allowing them to test how manufacturing methods affect whether an alloy morphs into a glass. An SSRL x-ray beam scanned both sets of alloys, then researchers fed the results into a database to generate new machine learning results, which were used to prepare new samples that underwent another round of scanning and machine learning.
By the experiment’s third and final round, Mehta said, the group’s success rate for finding metallic glass had increased from one out of 300 or 400 samples tested to one out of two or three samples tested. The metallic glass samples they identified represented three different combinations of ingredients, two of which had never been used to make metallic glass before.
Source: Northwestern University

Nanotehnologia purtătoare de autoturisme cu încărcare automată(Nanotechnology wearable self-charging power units)

Cercetătorii au dezvoltat un fotodetector auto-acționat prin cuplarea polimerului polimedil-siloxanic pe bază de silicon (PDMS) ca un TENG cu un material numit perovskit de halogenură organometalică¹. Materialul pe bază de halogenură de plumb prezintă proprietăți optoelectronice care sunt de dorit în celulele solare și diodele emițătoare de lumină.Dispozitivul auto-alimentat a demonstrat o reacție excelentă la lumina incidentă, în special când este expusă la lumină de intensitate redusă”, spune Mark Leung, autorul principal al studiului fotodetector. Datorită componentelor polimerice flexibile și transparente, și-a păstrat performanțele după ce a fost îndoit de 1.000 de ori și indiferent de orientarea luminii incidentate

Posted: Apr 12, 2018

Nanotechnology wearable self-charging power units

(Nanowerk News) Autonomy is a much-anticipated feature of next-generation microsystems, such as remote sensors, wearable electronic gadgets, implantable biosensors and nanorobots. KAUST researchers led by Husam Alshareef, Jr-Hau He and Khaled Salama have developed small standalone devices by integrating maintenance-free power units that produce and use their own fuel instead of relying on an external power source (Nano Energy, „MXene electrochemical microsupercapacitor integrated with triboelectric nanogenerator as a wearable self-charging power unit” and Advanced Materials, „A self-powered and flexible organometallic halide perovskite photodetector with very high detectivity”).
wearable power bracelet can capture and transform energy from human motion into electricity and store it in MXene supercapacitors to drive different sensors
The wearable power bracelet can capture and transform energy from human motion into electricity and store it in MXene supercapacitors to drive different sensors. (Image: KAUST)
Triboelectric nanogenerators (TENGs) capture mechanical energy from their surroundings, such as vibrations and random motion produced by humans, and convert it into electricity. In these tiny generators, frictional contact between materials of different polarity creates oppositely charged surfaces. Repeated friction causes electrons to hop between these surfaces, resulting in electric voltage.
„We exploited this triboelectric effect to harvest energy from simple movements, such as hand clapping, finger tapping and routine hand motion, to drive different types of sensors,” says Alshareef.
The researchers have developed a self-powered photodetector by coupling the silicone-based polymer polydimethylsiloxane (PDMS) as a TENG with a material called organometallic halide perovskite¹. The lead-halide-based material features optoelectronic properties that are desirable in solar cells and light-emitting diodes.
To streamline their design and eliminate the need for a motion actuator, He’s team fabricated the photodetector using two multilayered polymer-based sheets separated by a small gap. One sheet comprised the perovskite ultrathin film while the other contained a PDMS layer. The gap allowed the team to harness the triboelectric effect when the device was activated by finger tapping.
„The self-powered device showed excellent responsiveness to incident light, especially when exposed to light of low intensity”, says Mark Leung, the lead author of the photodetector study. Because of its flexible and transparent polymer components, it also retained its performance after being bent 1,000 times and regardless of the orientation of the incident light.
Pushing the boundaries further, the researchers engineered a wearable self-powered bracelet that can store the converted mechanical energy by combining a carbon-fiber-embedded silicone nanogenerator with MXene microsupercapacitors².
They incorporated nanogenerator and miniaturized electrochemical capacitors into a single monolithic device encased in silicone rubber. The leak-proof and stretchable shell provided a flexible and soft bracelet that fully conformed to the body. Fluctuations in the skin-silicone separation altered the charge balance between electrodes, causing the electrons to flow back and forth across the TENG and the microsupercapacitor to charge up.
In addition to exhibiting longer cycle life and short charging time, MXene microsupercapacitors can accumulate more energy in a given area than thin-film and micro-batteries, offering faster and more effective small-scale energy storage units for TENG-generated electricity. When active, the bracelet can use the stored energy to operate various electronic devices, such as watches and thermometers.
„Our ultimate goal is to develop a self-powered sensor platform for personalized health monitoring,” says Ph.D. student Qiu Jiang, the lead author of the self-charging band project. The team is now planning to introduce sensors into the system to detect biomarkers in human sweat.
Source: KAUST

Mecanismul de dezlipire oxidativă a nanotuburilor de carbon multiwall pentru nanofibrele de grafen(Mechanism of oxidative unzipping of multiwall carbon nanotubes to graphene nanoribbons)

Grafen, o latură bidimensională de atomi de carbon, a atras un interes enorm de la o bază largă a comunității de cercetare timp de mai mult de un deceniu. Granulele graphene (GNR), benzi înguste de grafen, care sunt cvasi unidimensionale, posedă caracteristici complementare față de corespondentul lor bidimensional al foilor de grafen. Pe baza calculelor teoretice, proprietățile electrice ale GNR pot fi controlate prin configurația de lățime și muchie și pot varia de la metal la semiconductori

Posted: Apr 12, 2018

Mechanism of oxidative unzipping of multiwall carbon nanotubes to graphene nanoribbons

(Nanowerk News) Graphene, a two-dimensional lattice of carbon atoms, has attracted enormous interest from a broad base of the research community for more than one decade. Graphene nanoribbons (GNRs), narrow strips of graphene, being quasi one-dimensional, possess complementary features relative to their two-dimensional counterpart of graphene sheets. Based on theoretical calculations, GNRs’ electrical properties can be controlled by the width and edge configuration and they can vary from being metallic to semiconducting.
The physical properties of the GNRs depend significantly on the size and number of layers, which in turn depend on their synthesis method.
There are three major approaches for synthesis of GNRs: cutting graphene by different lithographic techniques; bottom-up synthesis from polycyclic molecules; and unzipping of carbon nanotubes (CNTs). While the bottom-up method provides a route to precise edge control, and the lithographic method can afford GNRs with precise placement, the unzipping method has the advantage of mass-production on a large scale.
Intercalation-unzipping, oxidation, and exfoliation of carbon nanotubes
Intercalation-unzipping, oxidation, and exfoliation of carbon nanotubes. (Image: Kazan Federal University, Laboratory of Advanced Carbon Nanomaterials) (click on image to enlarge)
MWCNT unzipping methods can be classified into four major types: the reductive-intercalation-assisted approach, the oxidative unzipping, the electrochemical unzipping, and the group of methods that can be denoted as miscellaneous. The first approach is based on the well-known ability of alkali metals to intercalate graphite with expansion in the Z-axis direction.
Being applied toward MWCNTs, such lattice expansion induces extreme stress within the concentric walls, resulted in the bursting, or longitudinal opening, of the tubes. The resulting GNRs are highly conductive, but they remain multi-layered and foliated. Due to the attraction between the surfaces, they do not exfoliate to single-layer ribbons.
The oxidative approach involves treatment of MWCNTs in acidic oxidative media with the formulation almost identical to that used in production of graphene oxide (GO) from graphite by the Hummers method. The resulting product is graphene oxide nanoribbons (GONRs). Unlike GNRs obtained by the reductive-intercalation method, GONRs easily exfoliate in aqueous solution, and they can be obtained as single-layered structures.
A reaction mechanism for oxidative unzipping was proposed by Kosynkin et al (Nature, „Longitudinal Unzipping of Carbon Nanotubes to Form Graphene Nanoribbons”). Invoking the classical oxidation of the alkenes by permanganate in acids, the first step is the formation of manganate ester on a C-C bond, and the second step is the rupture of the C-C bond with formation of ketones at the newly formed edges.
This mechanism was further developed in the theoretical work by Rangel et al (The Journal of Chemical Physics, „Mechanism of Carbon Nanotubes Unzipping Into Graphene Ribbons”). The original synthesis spawned numerous studies on oxidative unzipping of MWCNTs. In many reports, the unzipping process was denoted as „chemical” as opposed to the „intercalation-exfoliation”, indicating that the permanganate-induced oxidative mechanism has been commonly accepted, and was even suggested toward unzipping SWCNTs.
The newly proposed mechanism was based on the Lab’s competences on the studies of the mechanism of GO formation of graphite that involves three consecutive steps: (a) intercalation of graphite by sulfuric acid with formation of a stage-1 H2SO4-graphite intercalation compound (GIC); (b) conversion of stage-1 H2SO4-GIC into pristine GO, and (c) exfoliation of GO to single-layer sheets upon exposure to water. Thus, under given conditions, formation of stage-1 H2SO4-GIC is unavoidable for any graphitic material. Subsequently, the mechanism of the oxidative unzipping of MWCNTs might be also intercalation-driven.
If this is correct, one should be able to stop the reaction after the first intercalation-unzipping step before the second oxidation step proceeds. If attained, this will afford unzipped but not oxidized or minimally oxidized products possessing properties similar to reductively unzipped GNRs obtained by potassium or sodium-potassium metal intercalation.
In this work (ACS Nano, „Revisiting the Mechanism of Oxidative Unzipping of Multiwall Carbon Nanotubes to Graphene Nanoribbons”), the Lab investigated the impact of the two key parameters, the KMnO4/MWCNT ratio, and the time of reaction on the structure and composition of as-obtained GNR products, and derived a revised and more complete understanding of the unzipping process.
The researchers demonstrated that the mechanism of the oxidative unzipping of MWCNTs is indeed intercalation-driven. The overall unzipping process involves the same three steps as in the course of GO production from graphite by the Hummers and modified Hummers methods: intercalation, oxidation, and exfoliation. With MWCNTs, the intercalation is associated with simultaneous unzipping.
At low KMnO4/MWCNT ratios, one can obtain GNRs with characteristics similar to those produced by reductive unzipping. 0.12 wt equiv KMnO4 is the threshold ratio sufficient for almost complete unzipping, with only small amounts of covalent oxidation. Controlling the KMnO4/MWCNT ratio and time of reaction allows one to produce GNRs with the properties varying in a broad continuous range from multi-layered graphenic GNRs through single-layered GONRs.
Thus, the team answered several questions that remained open in the field of unzipping MWCNTs, such as the reason why the inner-most walls of the nanotubes remain zipped.
The intercalation-driven reaction mechanism provides a rationale for the impossibility of unzipping single-wall and few-wall CNTs, and aids in a reevaluation of the data from the oxidative unzipping process.
Source: Kazan Federal University

Un pas mai aproape de utilizarea membranelor grafene nanoporoase ca filtre inteligente și senzori(One step closer to using nanoporous graphene membranes as smart filters and sensors)

au sintetizat cu succes o membrana de grafen cu pori a caror marime , forma si densitatea pot fi reglate cu precizie atomica la scara nanometrica.Porii din inginerie la nano-scala în grafen se pot schimba proprietățile fundamentale ale acestui material. Pentru un început devine permeabil sau asemănător sita. Numai această schimbare, combinată cu puterea intrinsecă a grafenului și nano-subțire, indică utilizarea ulterioară ca filtru cel mai rezistent, eficient din punct de vedere energetic și selectiv pentru substanțe extrem de mici, de la gaze cu efect de seră până la sare, până la biomolecule.Simulat la DIPC și testat experimental la ICN2, rezultatul este un nou tip de grafen care prezintă proprietăți electrice asemănătoare cu cele ale siliciului,

Posted: Apr 12, 2018

One step closer to using nanoporous graphene membranes as smart filters and sensors

(Nanowerk News) Researchers at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), the CiQUS research centre at the University of Santiago de Compostela (USC) and the Donostia International Physics Center (DIPC) have successfully synthesised a graphene membrane with pores whose size, shape and density can be tuned with atomic precision at the nanoscale. Led by ICREA Prof. Aitor Mugarza from the ICN2 and Prof. Diego Peña from CiQUS, their work brings us one step closer to unlocking the potential of this much lauded material in electronics, and in filtration and sensing applications.
The results have been published this week in Science („Bottom- up synthesis of multifunctional nanoporous graphene”), with ICN2 researcher Dr. César Moreno as first author. A patent for the resulting nanoporous graphene membrane has also been filed.
nanoporous graphene
Engineering pores at the nanoscale in graphene can change the fundamental properties of this material. For a start it becomes permeable or sieve-like. This change alone, combined with graphene’s intrinsic strength and nano-slimness, points to its future use as the most resilient, energy-efficient and selective filter for extremely small substances, from greenhouse gases to salt, to biomolecules.
But a second, perhaps less intuitive change also takes place when the spacing between pores is similarly reduced to a few atoms. Doing so transforms the graphene from semimetal to semiconductor, opening the door for its use in electronic applications, where it could be used to replace the bulkier, more rigid silicon components used today.
However, while all of this is true in theory, producing such a material requires a precision that current fabrication methods have yet to achieve, and look unlikely to ever do so. The problem is the approach: punching holes in or otherwise manipulating a material that is just one atom thick is an incredibly fiddly task. In the work described here, the team takes a “bottom up” approach based on the principles of molecular self-assembly and 2D polymerisation, effectively growing the graphene from scratch with the nanopores already built-in.
For this approach to work, you first need a very specific precursor molecule to use as the initial building blocks, designed such that they will behave as intended when subjected to different stimuli. In this work these precursors were designed and produced by synthetic chemistry specialists at CiQUS, before being taken to the ICN2 for the abovementioned “bottom-up” assembly of nanoporous graphene. Here they were submitted to several rounds of heating at high temperatures while placed on a gold surface, which serves to catalyse the reactions by which the molecules are first polymerised, to form long, lacelike “nanoribbons”, and then bonded laterally, to create the desired 2D “nanomesh” structure complete with evenly spaced, evenly sized pores.
Simulated at the DIPC and tested experimentally at the ICN2, the result is a new kind of graphene that exhibits electrical properties akin to those of silicon which can also act as a highly-selective molecular sieve. Applied in conjunction, these two properties are predicted to allow the development of combined filter and sensor devices which will not only sort for specific molecules, but will alternatively block or monitor their passage though the nanopores using an electric field. Such electrical readings would provide additional information as to precisely what concentrations of which molecule are passing through the pores and when, something which also points to possible applications in more efficient DNA sequencing.
Indeed, the real-world applications of such a tunable, uniformly nanoporous graphene membrane are manifold. They range from pollution monitoring and mitigation, to water desalinisation, and even applications in biomedicine, where such a slim, flexible, biocompatible membrane could be used to support failing organs like the kidney, one of the body’s natural filters.
Source: ICN2

Ipoteza puternică a lui Ivy ar putea conduce la adezivi medicali mai buni, la armura de luptă mai puternică(Ivy’s powerful grasp could lead to better medical adhesives , stronger battle armor)

Zhang a spus particule bogate in aceste proteine ​​au abilitati exceptionale de adeziv -abilitati care ar putea fi folosite in avantajul multor, de la ingineri biomedicale la producatorii de vopsea

Ivy's

Imprimare inteligentă: filme generatoare de energie și sticlă luminescente(Smart printing: power generating films and luminescent glass)

cernelurile cu jet de cerneală dezvoltate de cercetători la Fraunhofer IAP pot fi imprimate pe substraturi solide, precum și pe folii flexibile. De fapt, celulele solare și ecranele ecologice pot fi produse rapid și eficient din punct de vedere al costurilor.Materiale cuantice pentru industria afișelor
În plus față de OLED-urile, oamenii de știință din cadrul IAP studiază, de asemenea, QLED-uri bazate pe puncte cuantice de fosfură de indiu. Ele nu conțin cadmiu toxic folosit în mod convențional. Rezultatele până în prezent sunt esențiale pentru industrie. QLED bazate pe fosfură de indium se recuperează treptat pe avantajele de performanță ale sistemelor pe bază de cadmiu în multe domenii. În ceea ce privește luminanța, ele depășesc deja QLED-urile bazate pe cadmiu.

Posted: Apr 11, 2018

Smart printing: power generating films and luminescent glass

(Nanowerk News) They turn light into electricity or vice versa: the inkjet inks developed by researchers at the Fraunhofer IAP can be printed on solid substrates as well as on flexible foils. In effect, solar cells and organic displays can be produced fast and cost-effectively.
Together with research partners, the Fraunhofer scientists have developed methods to print organic photovoltaic elements for use in architecture and for the textile industry on film. With a solar module as façade element and a power-generating jacket, they present the potential of their work at the fair.
manufacturing of flexible photovoltaic elements
Flexible photovoltaic elements, manufactured on Fraunhofer IAP`s own pilot plant. (Image: Fraunhofer IAP)

Printed displays rolled up?
Also for displays, printing processes are utilized at the Fraunhofer IAP. Using specially developed inks from organic light sources and quantum dots, the researchers print, for example, organic light-emitting diodes (OLEDs) and quantum dot-based LEDs (QLEDs). The displays can also be printed on different materials. Printing on film makes them flexible to some degree.
„Until we can flexibly roll up our televisions, we still have a little research to do”, explains Dr. Armin Wedel, head of the research division Functional Polymer Systems at the Fraunhofer IAP. „Although there are already curved and even scrollable displays, they still have to be rolled up on rigid rolls with a defined diameter,” says the OLED specialist.

ESJET printing for high-resolution OLEDs
New perspectives for the production of printed displays result from the use of ESJET printing (electrostatic printing). The scientists at the Fraunhofer IAP are working on this procedure together with twelve other partners within the project Hi-Response, which is funded by the European Union.
The ESJET printing process allows the use of a wider range of inks, as even very viscous inks can be processed. The drop-on-demand system also makes it possible to set the thickness of the printed layer very precisely. The printed structures can be as small as 1 micron. In the future, the printing of high-resolution, active-matrix-driven OLEDs should be possible.

Quantum materials for the display industry
In addition to OLEDs, the IAP scientists are also researching QLEDs based on indium phosphide quantum dots. They are free of conventionally used toxic cadmium. The results so far are groundbreaking for the industry. Indium phosphide-based QLEDs are gradually catching up on the performance advantage of cadmium-based systems in many areas. Regarding luminance, they are already outperforming cadmium-based QLEDs.
Dr. André Geßner presents the research results in his presentation:
Concept For Full Color QD-Displays. Thursday, April 12, 10.00 to 10.20 a.m.; Estrel Convention Center, Berlin; Room II
Source: Fraunhofer-Institut für Angewandte Polymerforschung

Primul cip biosenzor din lume bazat pe cupru și oxid de grafen(World’s first biosensor chips based on copper and graphene oxide)

Cipurile pentru biosenzori sunt utilizate de companiile farmaceutice pentru a dezvolta medicamente. Aceste cipuri sunt, de asemenea, indispensabile pentru studierea cineticii interacțiunilor moleculare. Mai mult, ele ar putea servi drept bază pentru diferite tipuri de analizoare chimice utilizate pentru a găsi molecule care indică o boală și pentru a detecta substanțe periculoase în alimente sau în mediu, inclusiv scurgeri de la fabrici chimice, printre altele.

Posted: Apr 11, 2018

World’s first biosensor chips based on copper and graphene oxide

(Nanowerk News) Russian researchers from the Moscow Institute of Physics and Technology have developed biosensor chips of unprecedented sensitivity, which are based on copper instead of the conventionally used gold. Besides making the device somewhat cheaper, this innovation will facilitate the manufacturing process. The research findings are reported in the journal Langmuir(„Superior sensitivity of copper-based plasmonic biosensors”).
Biosensor chips are used by pharmaceutical companies to develop drugs. These chips are also indispensable for studying the kinetics of molecular interactions. Furthermore, they could serve as a basis for various kinds of chemical analyzers used to find molecules indicating a disease and to detect hazardous substances in food or the environment, including leaks from chemical plants, among other things.
The Russian research team from the Laboratory of Nanooptics and Plasmonics of MIPT’s Center for Photonics and 2D Materials has developed a sensing chip based on unconventional materials: copper and graphene oxide. As a result, their device achieves unmatched sensitivity, and yet its configuration is mostly standard and therefore compatible with existing commercial biosensors, e.g., such as Biacore, Reichert, BioNavis, or BiOptix.
Yury Stebunov, senior researcher at the Laboratory of Nanooptics and Plasmonics of the Center for Photonics and 2D Materials, MIPT
Yury Stebunov, senior researcher at the Laboratory of Nanooptics and Plasmonics of the Center for Photonics and 2D Materials, MIPT. (Image: Evgeniy Pelevin/MIPT)
“Our engineering solution is an important step towards developing biological sensors based on photonic and electronic technology,” says Valentyn Volkov, professor of the University of Southern Denmark, who also heads the Laboratory of Nanooptics and Plasmonics at MIPT. “By relying on standard manufacturing technologies and combining copper with graphene oxide — a material that has a great potential — we achieve a demonstrably high efficiency. This opens up new avenues for biosensor development.”
The most common material used in optoelectronics and photonics is gold. Nearly all commercial biosensor chips incorporate gold films several tens of nanometers thick — a nanometer is one billionths of a meter. The reason gold is so ubiquitous is that it has excellent optical properties and is chemically very stable. But even gold is not perfect. For one thing, it is expensive — specifically, high-purity gold costs over 25 times as much as high-purity copper. Also, gold is incompatible with the industrial processes used for manufacturing microelectronics, which severely limits its potential for application in device mass production.
Unlike gold, copper does not have these flaws. Its optical properties are on par with those of gold. Copper is used as an electrical conductor in microelectronics. However, it suffers from oxidation, or corrosion, and therefore has not been used in biochips. Now, MIPT researchers have solved this problem by covering the metal with a 10-nanometer dielectric layer. In addition to preventing oxidation, this altered the optical properties of the chip, making it more sensitive.
To further refine their biosensor design, the authors added a graphene oxide layer on top of the copper and dielectric films, enabling unprecedented sensitivity. This third material was originally obtained in 1859 as graphite oxide by Oxford University professor Benjamin C. Brodie Jr., a renowned English chemist. Later on, graphene oxide experienced a sort of a revival following the discovery of graphene — the first known two-dimensional material — by Russian-born University of Manchester physicists and MIPT graduates Andre Geim and Konstantin Novoselov. The work on graphene earned them the 2010 Nobel Prize in physics. Graphene oxide can be visualized as graphene — a one-dimensional sheet of carbon atoms bound in a honeycomb arrangement — with oxygen-containing groups dangling from some of the carbon atoms. These groups provide a link between the device surface and the protein molecules that are analyzed. In an earlier study, the authors used graphene oxide to increase the sensitivity of standard gold-based biosensors. The material proved to be beneficial for copper sensors as well.
Replacing gold with copper opens up the way for developing compact biosensing devices to be implemented in smartphones, portable gadgets, wearable devices, and smart clothes, because copper-based chips are compatible with conventional microelectronics technology. Scientists from across the world and electronics industry giants such as IBM and Samsung are putting a lot of effort into creating compact biosensors that could be built into electronic devices just like the present-day nano- and microelectromechanical motion sensors — accelerometers and gyroscopes. It is hard to overestimate the impact that biosensors would have — suffice to say that our devices would acquire a new sense organ. And this is not merely a metaphor: Major corporations are working on technologies to enable AI, intelligent gadgets, and biointerfaces that would serve as mediators between the human brain and a computer. A combination of these technologies could give rise to real cybernetic organisms.
“It is known that copper is susceptible to the corrosive influence of the environment. We have shown that protective dielectric films only tens of nanometers thick do more than just prevent oxidation: In some cases, they increase biosensor sensitivity,” says Yury Stebunov, the lead author of the paper and co-founder and CEO of GrapheneTek LLC. “We don’t see purely fundamental research as the final destination. Our solution will be available to potential customers before the end of the year. The technologies proposed in this study could be used to create miniature sensors and neural interfaces, and that’s what we’re working on right now.”
Source: Moscow Institute of Physics and Technology

Nanoembrama inspirată din punct de vedere biologic purifică fumul de gaze cu efect de seră din cărbune(Biologically inspired nanomembrane purges coal-fired smoke of greenhouse gases)

O membrană inspirată din punct de vedere biologic, destinată să curățe aproape complet dioxidul de carbon de fumul de la centralele pe bază de cărbune, a fost dezvoltată de oamenii de știință de la Sandia National Laboratories și de la Universitatea din New Mexico.
Lucrările brevetate, raportate recent în Nature Communications ( „Membrana lichidă enzimatică ultra-subțire pentru separarea și captarea CO2 2 ” ), au companii interesate de energie și energie care ar dori să reducă în mod semnificativ și ieftin emisiile de dioxid de carbon, una dintre cele mai răspândite gaze cu efect de seră și pentru a explora alte posibile utilizări ale invenției.

Posted: Apr 11, 2018

Biologically inspired nanomembrane purges coal-fired smoke of greenhouse gases

(Nanowerk News) A biologically inspired membrane intended to cleanse carbon dioxide almost completely from the smoke of coal-fired power plants has been developed by scientists at Sandia National Laboratories and the University of New Mexico.
The patented work, reported recently in Nature Communications („Ultra-thin enzymatic liquid membrane for CO22 separation and capture”), has interested power and energy companies that would like to significantly and inexpensively reduce emissions of carbon dioxide, one of the most widespread greenhouse gases, and explore other possible uses of the invention.
Enzymatic liquid membrane design and mechanism of carbon dioxide capture and separation
Enzymatic liquid membrane design and mechanism of carbon dioxide capture and separation. The Sandia/University of New Mexico membrane is fabricated by formation of 8-nanometer diameter mesopores. Using atomic layer deposition and oxygen plasma processing, the silica mesopores are engineered to be hydrophobic except for an 18-nm-deep region at the pore surface which is hydrophilic. Through capillary condensation, carbonic anhydrase enzymes and water spontaneously fill the hydrophilic mesopores to form an array of stabilized enzymes with an effective concentration greater than 10 times of that achievable in solution. These catalyze the capture and dissolution of carbon dioxide at the upstream surface and the regeneration of carbon dioxide at the downstream surface. The high enzyme concentration and short diffusion path maximizes capture efficiency and flux. (Image: Sandia National Laboratories) (click on image to enlarge)
The memzyme meets the Department of Energy’s standards by capturing 90 percent of power plant carbon dioxide production at a relatively low cost of $40 per ton.
Researchers term the membrane a „memzyme” because it acts like a filter but is near-saturated with an enzyme, carbonic anhydrase, developed by living cells over millions of years to help rid themselves of carbon dioxide efficiently and rapidly.
„To date, stripping carbon dioxide from smoke has been prohibitively expensive using the thick, solid, polymer membranes currently available,” says Jeff Brinker, a Sandia fellow, University of New Mexico regents’ professor and the paper’s lead author.
„Our inexpensive method follows nature’s lead in our use of a water-based membrane only 18 nanometers thick that incorporates natural enzymes to capture 90 percent of carbon dioxide released. This is almost 70 percent better than current commercial methods, and it’s done at a fraction of the cost.”
Coal power plants are one of the United States’ largest energy producers, but they have been criticized by some for sending more carbon dioxide into the atmosphere than any other form of electrical power generation. Still, coal burning in China, India and other countries means that U.S. abstinence alone is not likely to solve the world’s climate problems. But, says Brinker, „maybe technology will.”
The device’s formation begins with a drying process called evaporation-induced self-assembly, first developed at Sandia by Brinker 20 years ago and a field of study in its own right.
The procedure creates a close-packed array of silica nanopores designed to accommodate the carbonic anhydrase enzyme and keep it stable. This is done in several steps. First, the array, which may be 100 nanometers long, is treated with a technique called atomic layer deposition to make the nanopore surface water-averse or hydrophobic. This is followed by an oxygen plasma treatment that overlays the water-averse surface to make the nanopores water-loving or hydrophilic, but only to a depth of 18 nanometers. A solution of the enzyme and water spontaneously fill up and are stabilized within the water-loving portion of the nanopores. This creates membranes of water 18 nanometers thick, with a carbonic anhydrase concentration 10 times greater than aqueous solutions made to date.
The solution, at home in its water-loving sleeve, is stable. But because of the enzyme’s ability to rapidly and selectively dissolve carbon dioxide, the catalytic membrane has the capability to capture the overwhelming majority of carbon dioxide molecules that brush up against it from a rising cloud of coal smoke. The hooked molecules then pass rapidly through the membranes, driven solely by a naturally occurring pressure gradient caused by the large number of carbon dioxide molecules on one side of the membrane and their comparative absence on the other. The chemical process turns the gas briefly into carbonic acid and then bicarbonate before exiting immediately downstream as carbon dioxide gas. The gas can be harvested with 99 percent purity – so pure that it could be used by oil companies for resource extraction. Other molecules pass by the membrane’s surface undisturbed. The enzyme is reusable, and because the water serves as a medium rather than an actor, does not need replacement.
The nanopores dry out over long periods of time due to evaporation. This will be checked by water vapor rising from lower water baths already installed in power plants to reduce sulfur emissions. And, enzymes damaged from use over time can easily be replaced.
Says Brinker, „The very high concentration of carbonic anhydrase, along with the thinness of the water channel, result in very high carbon dioxide flux through the membrane. The greater the carbonic anhydrase concentration, the greater the flux. The thinner the membrane, the greater the flux.”
The membrane’s arrangement in a generating station’s flue would be like that of a catalytic converter in a car, suggests Brinker. The membranes would sit on the inner surface of a tube arranged like a honeycomb. The flue gas would flow through the membrane-embedded tube, with a carbon dioxide-free gas stream on the outside of the tubes. Varying the tube length and diameter would optimize the carbon dioxide extraction process.
„Energy companies and oil and gas utilities have expressed interest in optimizing the gas filters for specific conditions,” says Susan Rempe, Sandia researcher and co-author, who suggested and developed the idea of inserting carbonic anhydrase into the water solution to improve the speed by which carbon dioxide could be taken up and released from the membrane. „The enzyme can catalyze the dissolution of a million carbon dioxide molecules per second, vastly improving the speed of the process. With optimization by industry, the memzyme could make electricity production cheap and green,” she says.
The separation process could increase the amount of fuel obtained by enhanced oil recovery using carbon dioxide injected into existing reservoirs.
A slightly different enzyme, used in the same process, can convert methane – an even more potent greenhouse gas – to the more soluble methanol for removal, she says.
Prior cleansing by industrial scrubbers means that the rising smoke will be clean enough not to significantly impair membrane efficiency, says University of New Mexico professor and paper co-author Ying-Bing Jiang, who originated and developed the idea of using watery membranes based on the human body’s processes to separate out carbon dioxide. The membranes have operated efficiently in laboratory settings for months.
The procedure also could sequester carbon dioxide on a spacecraft, the authors mention, because the membranes operate at ambient temperatures and are driven solely by chemical gradients.
Source: Sandia National Laboratory