noiembrie 2017 – Pagina 6

Ridurile dau căldură unei răsturnări în grafenul colmatat(Wrinkles give heat a jolt in pillared graphene)

Măsurate de-a lungul celui mai lung plan, modelele cu octogonii au fost cu aproape 20% mai bune la transportul fononelor decât cele fără. „Rezultatele noastre arată că trăsături subtile, cum ar fi această configurație a joncțiunii, au un impact semnificativ asupra transportului termic”, a spus Shahsavari, profesor asistent de inginerie civilă și de mediu și de știință a materialelor și nanoengineering. „Având în vedere nevoile actuale în managementul termic și miniaturizarea dispozitivelor în multe nano- și microelectronice, acest studiu oferă un nou grad de libertate de a juca și de a îmbunătăți transportul termic”.

Posted: Nov 03, 2017
Wrinkles give heat a jolt in pillared graphene (Nanowerk News) Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University engineers.
Rice materials scientist Rouzbeh Shahsavari and alumnus Navid Sakhavand first built atom-level computer models of pillared graphene – sheets of graphene connected by covalently bonded carbon nanotubes – to discover their strength and electrical properties as well as their thermal conductivity.
In a new study, they found that manipulating the joints between the nanotubes and graphene has a significant impact on the material’s ability to direct heat. That could be important as electronic devices shrink and require more sophisticated heat sinks.

Heat transport through pillared graphene could be made faster by manipulating the junctions between sheets of graphene and the nanotubes that connect them, according to Rice University researchers. (Image: Lei Tao/Rice University)
The research appears in the American Chemical Society journal ACS Applied Materials and Interfaces („Asymmetric Junctions Boost In-plane Thermal Transport in Pillared Graphene”).
Researchers who study or are working to make pillared graphene have primarily viewed two characteristics of the theoretical material: the length of the pillars and their distance from each other. The new study suggests that a third parameter – the nature of the junction between the graphene and nanotubes – should also be considered.
A seamless connection between flat graphene, the atom-thick form of carbon, and round nanotubes requires adjustments to their characteristic six-member carbon rings. The simplest way is to give half the rings at the junction an extra atom. Six seven-member rings alternating with six six-member rings allow the sheet to make a 90-degree turn to become the tube.
But that’s not the optimal configuration for heat transport, according to the Rice team. It found that replacing six heptagons with three octagons would facilitate the turn while slightly stressing the graphene. That would wrinkle the graphene sheets’ top and bottom while not significantly changing transport at the junctions.
The researchers intuitively expected the wrinkles to lower thermal transport and were surprised to find that thermal transport across the „in-plane” graphene became faster with wrinkles. They determined that having fewer rings in the junctions between nanotubes and graphene meant less scattering of heat-carrying phonons, which kept them onboard for the bumpy ride.
Measured along the longest plane, models with the octagons were nearly 20 percent better at transporting phonons than those without. „Our results show that subtle features such as this junction configuration have a significant impact on thermal transport,” said Shahsavari, an assistant professor of civil and environmental engineering and of materials science and nanoengineering. „Given the current needs in thermal management and device miniaturization in many nano- and microelectronics, this study provides a new degree of freedom to play and improve thermal transport.”
The researchers thought phonon transport through the nanotubes, which they already knew was slower than in graphene, might be slower still under the influence of the octagons, but the altered interface didn’t appear to have a significant effect.
„The reason lies in the geometry,” Shahsavari said. „The lower the number of non-hexagonal rings in the junction (for example three octagons versus six heptagons), the lower the number of undesirable rings and thus lower phonon scattering and improved thermal transport.” Because the junctions can adopt many different geometries depending on the radius and chirality of the nanotube, there are many more potential configurations to be modeled, he said.

Source: Rice University

Materialul sintetic acționează ca un dispozitiv de mascare a insectelor(Synthetic material acts like an insect cloaking device)

Microsferele sintetice cu găuri la scară nanometrică pot absorbi lumina din toate direcțiile într-o gamă largă de frecvențe, făcându-i un candidat pentru acoperiri antireflective, Ca o acoperire antireflexivă, acest material ar putea avea aplicații în senzori și camere, unde captarea reflexiei nedorite a luminii ar putea crește raportul semnal-zgomot. Acest lucru ar putea fi deosebit de util în telescoape. Pentru aplicațiile cu celule solare, o acoperire cu brocozomi sintetici ar putea crește capturarea luminii la lungimi de undă multiple și din orice unghi datorită structurii 3D a mingii de fotbal a sferelor, ceea ce face necesar să se construiască dispozitive pentru urmărirea soarelui.

Posted: Nov 03, 2017
Synthetic material acts like an insect cloaking device (Nanowerk News) Synthetic microspheres with nanoscale holes can absorb light from all directions across a wide range of frequencies, making it a candidate for antireflective coatings, according to a team of Penn State engineers. The synthetic spheres also explain how the leaf hopper insect uses similar particles to hide from predators in its environment.
Scientists have long been aware that leaf hoppers extrude microparticles, called brochosomes, and wipe them on their wings. Because the particles are superhydrophobic, the leaf hopper’s wings stay dry in wet conditions. What was not understood before the current work is that the brochosomes also allow leaf hoppers and their eggs to blend in with their background at the wavelengths of light visible to their main predators, such as the ladybird beetle.

Synthetic brochosomes (false colored). (Image: Shikuan Yang, Birgitt Boschitsch/Penn State)
“We knew our synthetic particles might be interesting optically because of their structure,” said Tak-Sing Wong, assistant professor of mechanical engineering and the Wormely Family Early Career Professor in Engineering. “We didn’t know, until my former postdoc and lead author of the study Shikuan Yang brought it up in a group meeting, that the leaf hopper made these non-sticky coatings with a natural structure very similar to our synthetic ones. That led us to wonder how the leaf hopper used these particles in nature.”
Doing a search of the scientific literature turned up nothing about the leaf hopper brochosomes’ use as camouflage. But the pits’ sizes in the synthetic microspheres are very close to the wavelength of light, and can capture up to 99 percent of light ranging from ultraviolet through visible and into the near infrared. The particle surface acts like a metamaterial, the type of material used in cloaking devices.
“The problem is that in the field, these leaf hoppers produce very little of this product, and it is very hard to collect,” Wong said. “But we had already produced large quantities of these structures in the lab, enough to put inside a machine to look at their optical properties.”
In a paper published online in Nature Communications („Ultra-antireflective synthetic brochosomes”), the researchers simulated insect vision and found that the brochosomes are very likely camouflage coatings against leaf hopper predators. Camouflage is common in nature, but there are very few examples of natural antireflective coatings, moth eyes being a prominent exception. Moth eyes are covered in anti-reflective nanostructures that prevent light from reflecting off them at night when predators might see them.
The synthetic microspheres are produced via a rather complex five-step process using electrochemical deposition. However, the process can be scaled up and many different materials can be used to make the synthetic brochosomes, such as gold, silver, manganese oxide or even a conductive polymer.
“Different materials will have their own applications,” Wong said. “For example, manganese oxide is a very popular material used in supercapacitors and batteries. Because of its high surface area, this particle could make a good battery electrode and allow a higher rate of chemical reaction to take place.”
As an antireflective coating, this material could have applications in sensors and cameras, where capturing unwanted light reflection could increase the signal-to-noise ratio. This could be particularly useful in telescopes. For solar cell applications, a coating of synthetic brochosomes could increase light capture at multiple wavelengths and from every angle due to the 3D soccer ball-shape structure of the spheres, making it unnecessary to build devices to track the sun.
“This paper is more of a fundamental study,” Wong said. “In the future, we may try to extend the structure to longer wavelengths. If we made the structure a little larger, could it absorb longer electromagnetic waves such as mid-infrared and open up further applications in sensing and energy harvesting?” That remains to be studied.

Source: Penn State Materials Research Institute

Să fie lumină (albă): Materialele noi strălucesc(Let there be (white) light: New materials shine out)

Aceste materiale ar putea fi cheile pentru diodele de lumină de generație următoare și alte dispozitive care interconvertesc lumina și electricitatea, inclusiv celulele solare.
Lumina-emitatoare de 2-D perovskites sunt atractive din cauza costurilor lor reduse și tunability. Folosind diferite lungimi de distanțiere organice di-funcționale, s-au sintetizat o serie de noi hibrizi perovskiți de bromură de plumb anorganic-anorganic, de către cercetătorii de la Universitatea Northwestern.
Schimbarea lungimii ionilor încărcați pozitiv organic (cationi) induce o distorsionare a straturilor anorganice perovskite 2-D din material, ceea ce face ca straturile să aibă o structură ondulată sau ondulată. Deoarece distorsiunea cauzată de diferitele lungimi de cationi crește, lărgimea de bandă de frecvență și durata de viață a emisiilor fotoluminescente ale materialelor cresc.

Posted: Nov 03, 2017
Let there be (white) light: New materials shine out (Nanowerk News) Changing how we light our homes and offices could save energy, but new lighting technology requires new materials with the right properties. Materials called hybrid perovskites could be vital in making change possible.
Scientists discovered that changing the length of small spacer ions located between the perovskite’s internal layers manipulates the structure, distorting the layers to look like corrugated cardboard (Journal of the American Chemical Society, „White-light emission and structural distortion in new corrugated two-dimensional lead bromide perovskites”). The shortest spacer studied led to the most distorted structure. The structure emitted white light, comparable to commercial fluorescent lights.

The color coordinate map illustrates the colors of light emitted by different hybrid perovskites (with varying degrees of internal structural distortion) relative to pure white (corresponding to the yellow circle). The insert is a photo of the white light emitted by the most distorted material in the study (abbreviated α-(DMEN)PbBr4, also shown as a blue circle in the color map) after stimulation by ultraviolet radiation. (Image: Mercouri Kanatzidis, Northwestern University)
A new design tool based on understanding how spacers alter the light emitted could lead to new materials. These materials could be the keys to next-generation light-emitting diodes and other devices that interconvert light and electricity, including solar cells.
White-light–emitting 2-D perovskites are attractive because of their low cost and tunability. Using different lengths of di-functional organic spacers, a series of new hybrid organic-inorganic lead bromide perovskites were synthesized by researchers at Northwestern University.
Changing the length of the organic positively charged ions (cations) induces a distortion of the 2-D perovskite inorganic layers in the material, making the layers take on a wavy or corrugated structure. As the distortion caused by the different cation lengths increases, the frequency bandwidth and the lifetime of the materials’ photoluminescent emission increases.
Having the largest internal distortion of all the materials prepared in this study, the compound α-(DMEN)PbBr4 emits white light with a color rendering index of 73, which is similar to a commercial fluorescent light source. This correlation between structure and properties demonstrates that crystal structures of hybrid organic-inorganic perovskites can be manipulated to tune bandwidth and lifetime of the photoluminescent emission by varying the extent of the inorganic layer distortion.
With abundant choices of organic molecules available, many new exciting perovskite materials can be prepared, leading to an even deeper understanding of the science of these materials and impacting optoelectronic applications such as solid-state lighting.

Source: U.S. Department of Energy, Office of Science

Nanosilica dendritică fibroasă: nanomaterialul all-in-one pentru energie, mediu și sănătate(Dendritic fibrous nanosilica: all-in-one nanomaterial for energy, environment and health)

DFNS pare a fi Nanomaterial All-in-One și are un potențial imens pentru dezvoltarea viitoare. Deși DFNS a fost dotat cu proprietăți fizice și chimice excelente și prezintă rezultate excepționale în diferite aplicații, evoluția DFNS din studiile fundamentale de cercetare din laborator pentru a fi utilizată în industrie va depinde de colaborările dintre cercetătorii universitari și industrie.
Astfel s-au obținut progrese remarcabile în sinteza și aplicațiile DFNS, iar DFNS pare să fi demonstrat un mare potențial ca o alternativă superioară materialelor silice convenționale, cum ar fi Stöber silica, MSN, MCM-41 și SBA-15, printre altele. Costul redus, activitatea înaltă și stabilitatea pronunțată a numeroaselor materiale pe bază de nanosilică fibroasă dendritică susțin argumentul nostru că această clasă de materiale va găsi o utilizare practică pentru o gamă largă de aplicații, de la cataliză până la captarea gazelor, de la recoltarea și depozitarea energiei la livrarea de medicamente , de la chimie analitică la remedierea mediului și multe altele.

Posted: Nov 03, 2017
Dendritic fibrous nanosilica: all-in-one nanomaterial for energy, environment and health (Nanowerk News) Dendritic fibrous nanosilica (DFNS) attracted a great deal of attention in a large number of scientific disciplines such as catalysis, solar energy harvesting (photocatalysis, solar cells, etc.), energy storage, self-cleaning antireflective coatings, surface plasmon resonance (SPR)-based ultra-sensitive sensors, CO2 capture, and biomedical applications (drug delivery, protein and gene delivery, bioimaging, photothermal ablation, Ayurvedic and radiotherapeutics drug delivery, etc.).

Dendritic fibrous nanosilica (DFNS), also known as KCC-1, has a unique fibrous morphology and a high surface area with improved accessibility to the internal surface, tunable pore size and volume, controllable particle size, which made it useful in the fields of energy, environment, and health. (Image: Ayan Maity, Vivek Polshettiwar) (click on image to enlarge)
As discussed in this review (ChemSusChem, „Dendritic Fibrous Nanosilica for Catalysis, Energy Harvesting, Carbon Dioxide Mitigation, Drug Delivery, and Sensing”), the unique fibrous morphology of the DFNS family of materials bestows them with several important properties that were brilliantly exploited for use in a range of applications. The fibers of DFNS were functionalized with a range of organic groups, ionic liquids, organometallic complexes, polymers, peptides, enzymes, DNA, genes, etc. They were also loaded with metal nanoparticles, bi-metallic nanoparticles, even with single atoms of metals, quantum dots, and metal oxides and hydroxides. They were also used as hard templates for the synthesis of high surface area carbon with fibrous morphology. DFNS-based zeolites were also synthesized with unique activities.
DFNS provided a means to load large amount of catalytic active sites with exceptionally high accessibility compared to conventional mesoporous silica materials. Additionally, due to the radially oriented pores (channels), the size of which increased from the center of the sphere to its outer surface, reactants were able to easily access active sites within the channels, increasing their interaction with catalytic sites. This led to a multifold increase in their catalytic activity.
DFNS was cleverly used to develop novel photocatalysts by coating with γ-C3N4 and TiO2. The fibrous morphology of DFNS not only facilitated mass transfer and improved accessibility but also facilitated the formation of a uniform conformal coating and a high loading of semiconductors and guest molecules.
Notably, due to the fibrous structure of the material, the light harvesting properties of the catalyst were enhanced due multiple scattering effects and the reflection of a large amount of incident light. DFNS was also used to improve the performance of dye sensitized solar cells (DSSCs). In addition to energy harvesting, DFNS-coated carbon spheres were also used for energy storage using supercapacitors.
Functionalized DFNS, such as DFNS-amines and DFNS-oxynitrides, were successfully used to develop efficient CO2 sorbents, which could contribute in tackling the potentially dangerous climate change issue. Functionalized DFNS was also used to remove pollutants such as toxic metal ions, phosphorus, polyaromatic hydrocarbons, etc. from water bodies, which is a serious environmental concern.
DFFNS was efficiently used to deliver various anti-cancer drugs, and even the delivery of the Ayurvedic drug curcumin, DNA, genes and antimicrobial enzymes was achieved. In addition, a number of auxiliary functions were integrated into DFNS, such as stimuli responsiveness (light to thermal), fluorescence, radioactivity, anti-reflectance, superhydrophobicity, etc. This allows for their application in photothermal ablation therapy, real-time bioimaging, self-cleaning coatings, etc.
The sensing and quantification of pollutants was achieved using DFNS-based surface plasmon resonance (SPR). It was also used for an ultrasensitive enzyme-linked immunosorbent assay (ELISA+) with a 2000-fold enhancement in detection sensitivity.
DFNS seems like All-in-one-Nanomaterial and have huge potential for future development. Although DFNS has been gifted with excellent textural, physical and chemical properties and shows exceptional results in various applications, the evolution of DFNS from fundamental research studies in the laboratory to being used in industry will depend on collaborations between academic researchers and industry.
Thus, remarkable advances in the synthesis and applications of DFNS were achieved, and DFNS seems to have demonstrated great potential as a superior alternative to conventional silica materials such as Stöber silica, MSN, MCM-41, and SBA-15, among others. The low cost, high activity and pronounced stability of numerous dendritic fibrous nanosilica-based materials support our argument that this class of material will find practical use for a range of applications, from catalysis, to gas capture, from energy harvesting and storage to drug delivery, from analytical chemistry to environmental remediation and more.

Source: Tata Institute of Fundamental Research

O lume nouă de lumină ciudată(A strange new world of light)

au dezvoltat materiale nanostructurate care pot produce stări complet noi de lumină care prezintă comportament ciudat, cum ar fi îndoirea într-o spirală, tirbușirea și împărțirea ca o furculiță.

Posted: Nov 02, 2017
A strange new world of light (Nanowerk News) There’s nothing new thing under the sun – except maybe light itself.
Over the last decade, applied physicists have developed nanostructured materials that can produce completely new states of light exhibiting strange behavior, such as bending in a spiral, corkscrewing and dividing like a fork.
These so-called structured beams not only can tell scientists a lot about the physics of light, they have a wide range of applications from super-resolution imaging to molecular manipulation and communications.
Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a tool to generate new, more complex states of light in a completely different way.

A metasurface uses circularly polarized light to generate and control new and complex states of light, such swirling vortices of light. The new tool can be used to not only explore new states of light but also new applications for structured light. (Image: Second Bay Studio/Harvard SEAS)
The research is published in Science.
„We have developed a metasurface which is a new tool to study novel aspects of light,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the paper. „This optical component makes possible much more complex operations and allows researchers to not only explore new states of light but also new applications for structured light.”
The Harvard Office of Technology Development has protected the intellectual property relating to this project and is exploring commercialization opportunities.
The new metasurface connects two aspects of light, known as orbital angular momentum and circular polarization (or spin angular momentum). Polarization is direction along which light vibrates. In circularly polarized light, the vibration of light traces a circle. Think about orbital angular momentum and circular polarization like the motion of a planet. Circular polarization is the direction in which a planet rotates on its axis while orbital momentum describes how the planet orbits the sun.
The fact that light can even carry orbital momentum is a relatively recent discovery – only about 25 years old?– but it’s this property of light which produces strange new states, such as beams in the shape of corkscrews.

A metasurface can generate strange new beams of light that swirl and corkscrew. The black hole in the center of these vortices can be used to image features smaller than half a wavelength of light or move tiny molecules. (Image: Capasso Lab/Harvard SEAS)
Previous research has used the polarization of light to control the size and shape of these exotic beams but the connection was limited because only certain polarizations could convert to certain orbital momentums.
This research, however, significantly expands that connection.
„This metasurface gives the most general connection, through a single device, between the orbital momentum and polarization of light that’s been achieved so far,” said Robert Devlin, co-first author of the paper and former graduate student in the Capasso Lab.
The device can be designed so that any input polarization of light can result in any orbital angular momentum output – meaning any polarization can yield any kind of structured light, from spirals and corkscrews to vortices of any size. And, the multifunctional device can be programmed so that one polarization results in one vortex and a different polarization results in a completely different vortex.
„This is a completely new optical component,” said Antonio Ambrosio, Principal Scientist at Harvard Center for Nanoscale Systems (CNS) and co-first author of the paper. „Some metasurfaces are iterations or more efficient, more compact versions of existing optical devices but, this arbitrary spin-to-orbital conversion cannot be done with any other optical device. There is nothing in nature as well that can do this and produce these states of light.”
One potential application is in the realm of molecular manipulation and optical tweezers, which use light to move molecules. The orbital momentum of light is strong enough to make microscopic particles rotate and move.
„You can imagine, if we illuminate the device with one polarization of light, it will create a force of a particular kind,” said Ambrosio. „Then, if you want to change the force, all you need to do is change the polarization of the incoming light. The force is directly related to the design of the device.”
Another application is high-powered imaging. The black hole in the center of the vortex, known as the zero-light intensity region, can image features smaller than the diffraction limit, which is usually half of the wavelength of light. By changing the polarization of light, the size of this center region can be changed to focus different-sized features.
But these beams can also shed light on fundamental questions of physics.
„These particular beams are first and foremost of fundamental scientific interest,” said Noah Rubin, co-first author of the paper and graduate student in the Capasso Lab. „There is interest in these beams in quantum optics and quantum information. On the more applied side, these beams could find application in free-space optical communication, especially in scattering environments where this is usually difficult. Moreover, it has been recently shown that similar elements can be incorporated into lasers, directly producing these novel states of light. This may lead to unforeseen applications.”

Source: By Leah Burrows, Harvard John A. Paulson School of Engineering and Applied Sciences

Noua tehnică simplificată face din nanofoam metalic ușor(New, simplified technique makes light metallic nanofoam)

„Aceasta deschide o nouă platformă pentru explorări materiale interesante”, a spus el.
Noua tehnică folosește nanofire de paladiu ca blocuri de construcție. Nanofirele se pun în apă, apoi se amestecă într-o suspensie cu vibrații ultrasonice. Suspensia este rapid scufundată în azot lichid pentru a îngheța firele în loc. În cele din urmă, amestecul de gheață-nanofire este plasat într-un vid până când gheața se evaporă, lăsând în urmă o spumă pură de nanofire de paladiu. Densitatea materialului este la fel de mică ca o mie de densitate de paladiu în forma metalică în vrac și poate fi reglată pentru aplicații diferite

Posted: Nov 02, 2017
New, simplified technique makes light metallic nanofoam (Nanowerk News) A simple method for manufacturing extremely low-density palladium nanofoams could help advance hydrogen storage technologies, reports a new study from the University of California, Davis (Chemistry of Materials, „Tunable Low Density Palladium Nanowire Foams”).

UC Davis physicists Dustin Gilbert, Kai Liu and colleagues have come up with a new, simpler method to make a nanofoam of palladium. A nanofoam is a low density, porous material with very small pore size. The foamy metal could be used to store hydrogen in vehicles or for other purposes. (Image: Dustin Gilbert and Kai Liu, UC Davis)
A nanofoam is what it sounds like – a foamy version of some material, filled with very small pores. First introduced about 20 years ago, metallic nanofoams have potential for diverse applications. The porous structures are strong and lightweight – like their natural counterparts of bone and cork. Palladium and certain other metal nanofoams can also rapidly store and release hydrogen, making them an ideal candidate for hydrogen fuel cells.
But before cars can start fueling up via nanofoam, using metallic foams on an industrial scale must overcome challenges including demanding manufacturing conditions, contamination and poor crystallinity, said senior author Kai Liu, professor of physics in the UC Davis College of Letters and Science. It is also difficult to achieve extremely lightweight foams without compromising their stability, Liu noted.
Traditional metallic foam manufacturing techniques may require high temperature, high pressure and controlled chemical environments. The UC Davis-led team instead relies on a wet chemistry approach that is well-suited for industrial applications and adaptable to other types of lightweight metal foams as well, Liu said.
„This opens up a whole new platform for exciting materials explorations,” he said.
The new technique uses nanowires of palladium as building blocks. The nanowires are put in water, then mixed into a slurry with ultrasonic vibrations. The slurry is quickly immersed in liquid nitrogen to freeze the wires in place. Finally, the ice-nanowire mix is placed in a vacuum until the ice vaporizes, leaving behind a pure palladium nanowire foam. The density of the material is as low as one-thousandth of the density of palladium in it’s bulk metal form and can be tuned for different applications, the team found.
The researchers also studied the hydrogen storage properties of the palladium nanofoam, finding the material demonstrated excellent loading capacity and rate of absorption. The nanofoam exhibits excellent thermodynamic stability, as measured by specialized calorimetric techniques at the UC Davis Peter A. Rock Thermochemistry Laboratory. The laboratory is led by study co-author Alexandra Navrotsky, who holds the Edward Roessler Chair in Mathematical and Physical Science.

Source: University of California – Davis

Un sistem de testare enzimatică bioluminescent pentru evaluarea toxicității nanomaterialelor de carbon(A bioluminescent enzymatic test system for assessing the toxicity of carbon nanomaterials)

dezvoltarea nanotehnologiei a dus la răspândirea utilizarea nanomaterialelor în diverse domenii ale industriei.
Sistemul de testare a fost deja testat pentru capacitatea de a determina rapid prezența în mediu a unor astfel de substanțe toxice precum metalele grele sau pesticidele. Noi prezicem ca moleculele de exprimare moleculara „Enzymolum” vor fi utilizate pe scara larga in diferite sfere. „utilizarea reactivului bioluminescent „Enzymolum” pentru a testa toxicitatea nanomaterialelor. „Enzymolum” este un sistem enzimatic unic al mai multor molecule izolate de bacterii luminoase marine.

Posted: Nov 02, 2017
A bioluminescent enzymatic test system for assessing the toxicity of carbon nanomaterials (Nanowerk News) Official website of the Russian Science Foundation reports that a group of scientists from Siberian Federal University and Krasnoyarsk Scientific Center of the SB RAS has developed a bioluminescent enzymatic test system for assessing the toxicity of carbon nanomaterials.
Its distinctive features are simplicity, fast reaction speed and high sensitivity. The results of the study are published in the journal Toxicology in Vitro („Bioluminescent enzyme inhibition-based assay to predict the potential toxicity of carbon nanomaterials”).
The scientists proposed using the bioluminescent reagent „Enzymolum” to test the toxicity of nanomaterials. „Enzymolum” is a unique enzymatic system of several molecules isolated from marine luminous bacteria. The intensity of the luminescence of the reagent varies under the action of various additives. Scientists have tested the ability of commercial nanomaterials, such as various carbon nanotubes and fullerenes, to suppress the luminescence of the enzymatic system. The greatest inhibitory effect was observed for multiwalled nanotubes.
It should be noted that such an action was fixed at concentrations of nanomaterials exceeding those expected in the environment. However, with the increase in their application, we can expect an increase in the concentrations occurring in nature.
According to Elena Esimbekova, an Associate Professor of the Department of Biophysics at the School of Fundamental Biology and Biotechnology of SibFU, a researcher at the Institute of Biophysics of the Krasnoyarsk Scientific Center of the SB RAS, the development of nanotechnology has led to the widespread use of nanomaterials in various fields of industry.
At present, artificially created nanoparticles, primarily on the basis of carbon, are actively used in the production of medicines, cosmetics and in the food industry: „We have been developing the ‘Enzymolum’ test systems over the past ten years. Today it is an easy-to-use technology. Reagent is a small dried disk with enzymes included in them. Each of the disks is designed to carry out one measurement. Disks can be stored for a long time without loss of properties. The analysis itself takes 2 or 3 minutes. After that, you have a result – whether the solution of the studied sample affects the glow of the biological material. Based on this it can be concluded wether there is potential toxicity. The test system has already been tested for the ability to quickly determine the presence in the environment of such toxicants as heavy metals or pesticides. We predict that the molecular express-biotest ‘Enzymolum’ will be widely used in different spheres.”
The research was carried out with the support of the Russian Science Foundation in the framework of the project „New methodology of complex express assessment of soil quality and contamination based on enzymatic bioluminescent systems”.

Source: Siberian Federal University

Senzori bazați pe chip cu incredibilă sensibilitate(Chip-based sensors with incredible sensitivity)

Acest tip de senzor este format din sfere solide și nu este compatibil cu metodele de microfabricare, dar recent, Tadigadapa și echipa sa au dezvoltat o modalitate inovatoare de a dezvolta coji microsferice din sticlă cu chip cu senzitivități incredibile care pot fi utilizate pentru mișcare, temperatură, presiune sau biochimie detectare. Puteți face un senzor de umiditate cu adevărat sensibil.Poti face senzatia chimica, senzatia de vapori, senzatia biofizica, senzatia de presiune si senzatia de temperatura deosebita

Posted: Nov 02, 2017
Chip-based sensors with incredible sensitivity (Nanowerk News) In London’s St. Paul’s Cathedral, a whisper can be heard far across the circular whispering gallery as the sound curves around the walls. Now, an optical whispering gallery mode resonator developed by Penn State electrical engineers can spin light around the circumference of a tiny sphere millions of times, creating an ultrasensitive microchip-based sensor for multiple applications.
“Whispering gallery mode resonators, which are basically optical resonators, have been intensely studied for at least 20 years,” said Penn State electrical engineering professor Srinivas Tadigadapa. “What people have done is to take an optical fiber and touch the end with a blow torch. When the melted fiber re-condenses, it forms a sphere at the tip. This can be coupled to a light source to make a sensor.”
That type of sensor consists of solid spheres and is not compatible with microfabrication methods, but recently Tadigadapa and his team developed an innovative way to grow on-chip glass microspherical shells with incredible sensitivities that potentially can be used for motion, temperature, pressure or biochemical sensing.

Chip-scale glass microspherical shell sensor array blown on a silicon substrate. Insert is a near-perfect spherical shell. (Image: Tadigadapa Lab/Penn State)
The hollow borosilicate glass spheres are blown from sealed and pressurized cylindrical cavities etched into a silicon substrate. Using a glassblowing technique, the thin glass wafer, under high heat and external vacuum pressure, forms an almost perfect bubble. The researchers grew arrays of spheres from 230 microns to 1.2 millimeters in diameter with wall thicknesses between 300 nanometers and 10 micrometers.
“The bottom of the sphere is thinned until it is basically a hole,” Tadigadapa said. “You can put the light on the outside of the sphere but do all the chemistry on the inner face of the shell. You can bring in any analyte that you want to identify, but it goes on the inner surface. That brings in a lot of possibilities. You can do chemical sensing, vapor sensing, biophysical sensing, pressure sensing and really outstanding temperature sensing.”
After many failed attempts, the team discovered that the key to making a high- quality sensor lay in making sure that the equatorial plane of the sphere, its center, is above the surface of the chip.
To get an understanding of the quality of their spheres, Tadigadapa’s Ph.D. student Chenchen Zhang and recent Ph.D. graduate Eugene Freeman worked with Alexander Cocking, a Ph.D. student in the lab of Penn State laser expert Zhiwen Liu, professor of electrical engineering.
“We make the bubbles and then take them to Dr. Liu’s lab to get the resonance levels and make the measurements,” said Zhang, lead author on a paper describing their work in Scientific Reports(„On-Chip Glass Microspherical Shell Whispering Gallery Mode Resonators”).
This result will have particular significance for lab-on-a-chip biophysical sensing for disease sensing, Zhang said. “Or by adding a polymer coating on the inside of the bubble, you could make a really sensitive humidity sensor.”
Tadigadapa added, “There are some really exciting possibilities. I think it will spawn a large follow-up work.”

Source: Penn State Materials Research Institute

Forța electrostatică preia polimerii bioinpuși(Electrostatic force takes charge in bioinspired polymers)

Acest avans s-ar putea dovedi util în proiectarea de noi materiale bioinpuse și inteligente pentru aplicații variind de la livrarea de medicamente până la sensibilizarea la remedierea contaminanților de mediu. O clasa de polimeri, numite coacervates, care se separa ca ulei si apa si formeaza o substanta asemanatoare cu gelul

Posted: Nov 02, 2017
Electrostatic force takes charge in bioinspired polymers (Nanowerk News) Researchers at the University of Illinois and the University of Massachusetts, Amherst have taken the first steps toward gaining control over the self-assembly of synthetic materials in the same way that biology forms natural polymers. This advance could prove useful in designing new bioinspired, smart materials for applications ranging from drug delivery to sensing to remediation of environmental contaminants.
Proteins, which are natural polymers, use amino acid building blocks to link together long molecular chains. The specific location of these building blocks, called monomers, within these chains creates sequences that dictate a polymer’s structure and function. In the journal Nature Communications („Sequence and entropy-based control of complex coacervates”), the researchers describe how to utilize the concept of monomer sequencing to control polymer structure and function by taking advantage of a property present in both natural and synthetic polymers – electrostatic charge.

Inspired by the principles of natural polymer synthesis, Illinois chemical and biomolecular engineering professor Charles Sing, left, and graduate students Jason Madinya and Tyler Lytle co-authored a study that found they could create new synthetic materials by tuning the electrostatic charge of polymer chains. (Photo by L. Brian Stauffer)
„Proteins encode information through a precise sequence of monomers. However, this precise control over sequence is much harder to control in synthetic polymers, so there has been a limit to the quality and amount of information that can be stored,” said Charles Sing, a professor of chemical and biomolecular engineering at Illinois and a study co-author. „Instead, we can control the charge placement along the synthetic polymer chains to drive self-assembly processes.”
„Our study focuses on a class of polymers, called coacervates, that separate like oil and water and form a gel-like substance,” said Sarah Perry, a study co-author and University of Massachusetts, Amherst chemical engineering professor, as well as an Illinois alumna.
Through a series of experiments and computer simulations, the researchers found that the properties of the resulting charged gels can be tuned by changing the sequence of charges along the polymer chain.
„Manufacturers commonly use coacervates in cosmetics and food products to encapsulate flavors and additives, and as a way of controlling the ‘feel’ of the product,” Sing said. „The challenge has been if they need to change the texture or the thickness, they would have to change the material being used.”
Sing and Perry demonstrate that they can rearrange the structure of the polymer chains by tuning their charge to engineer the desired properties. „This is how biology makes the endless diversity of life with only a small number of molecular building blocks,” Perry said. „We envision bringing this bioinspiration concept full circle by using coacervates in biomedical and environmental applications.”
The results of this research open a tremendous number of opportunities to expand the diversity of polymers used and the scale of applications, the researchers said. „Currently, we are working with materials on the macro scale – things that we can see and touch,” Sing said. „We hope to expand this concept into the realm of nanotechnology, as well.”

Source: University of Illinois at Urbana-Champaign

Soldații viitorului suprem uman il sperie pe Vladimir Putin(Super-Human Future Soldiers Scare Vlademir Putin)

viitorii soldați ‘sci-fi’ super-umani sunt mai distructivi decât bombele nucleare, nu simt nici o teamă sau durere și ne-au amintit de propria noastră îngrijorare cu privire la viitorii roboți militari în stil Terminator

Super

Stofele inteligente obțin un upgrade major printr-o serie de primele de cercetare(Smart fabrics get major upgrade through a series of research firsts)

Noua tehnologie care foloseste semnale electronice intr-o tesatura inteligenta ar putea conduce la un echipament avansat de materiale periculoase care protejeaza impotriva chimicalelor toxice,Progresul ar putea avea mari implicații pentru personalul militar, serviciul de urgență și alți lucrători care se bazează pe protecția „haz-mat” pentru a-și desfășura activitatea și pentru ai menține pe ceilalți în siguranță. dispozitivele SOFT care prezintă MOF prezintă o conductivitate sigură, o porozitate sporită, flexibilitate și stabilitate la spălare. Țesăturile sunt, de asemenea, stabile în căldură, au o durată de depozitare bună și păstrează o gamă largă de utilități în condiții umede.

Posted: Nov 01, 2017
Smart fabrics get major upgrade through a series of research firsts (Nanowerk News) New technology that harnesses electronic signals in a smart fabric could lead to advanced hazardous-material gear that protects against toxic chemicals, according to research from Dartmouth College.
The advancement could have big implications for the military, emergency service personnel and other workers that rely on „haz-mat” protection to perform their work and keep others safe.
In research published in the Journal of the American Chemical Society („Self-Organized Frameworks on Textiles (SOFT): Conductive Fabrics for Simultaneous Sensing, Capture, and Filtration of Gases”), the chemistry team of Katherine Mirica and Merry Smith describe the creation of new smart fabrics – named SOFT, for Self-Organized Framework on Textiles – in what is noted as the first demonstration of simultaneous detection, capture, pre-concentration and filtration of gases in a wearable that uses conductive, porous materials integrated into soft textiles.

The SOFT e-textile uses metal-organic frameworks (MOFs) to improve detection and protection from toxic chemicals. (Image: K. A. Mirica)
According to the study, the SOFT devices have the potential for use in sensing applications ranging from real-time gas detection in wearable systems, to electronically accessible adsorbent layers in protective equipment like gas masks.
„By adding this fabric to a protective suit, sensors can alert the user if a chemical is penetrating the hazardous-material gear,” said Katherine Mirica, an assistant professor of chemistry at Dartmouth College. „This is not just passive protection, the textile can actively alarm a user if there is a tear or defect in the fabric, or if functional performance is diminished in any other way.”
Among other firsts described in the research are flexible, textile-supported electronic sensors based on materials known as metal-organic frameworks, or MOFs. In the study, the authors also describe a „simple” approach for integrating these conductive, porous materials into cotton and polyester fabrics to produce the e-textiles.
As part of the study, the Dartmouth team demonstrated that the new smart fabric can detect common toxic chemicals. Both the vehicle exhaust pollutant, nitric oxide, and the corrosive poison that reminds most of rotten eggs, hydrogen sulfide, were effectively identified by the SOFT system. In addition to sensing the chemicals, the electronic textiles are capable of capturing and filtering the dangerous toxins.
„Metal-organic frameworks are the future of designer materials, just like plastics were in the post-WWII era,” said Mirica. „By integrating the MOFs into our SOFT devices, we dramatically enhance the performance of smart fabrics that are essential to safety and security.”
The research team also describes a one-step e-textile fabrication method based on MOFs that likely constitutes the first use of direct self-assembly to deposit the conductive material on textiles.
In a process that Mirica describes as „similar to a building framework assembling itself,” cotton and polyester textiles coated with conductive crystals at the fiber-level are created by direct self-assembly of molecules with organic molecular struts connected by metallic linkers from solution.
Wearable electronics are thought to have great potential in areas including homeland security, communication and healthcare. Soldiers, emergency personnel, factory workers and others that risk exposure to toxic chemicals could benefit from the new smart fabrics. The materials could also help medical patients that require monitoring of specific airborne chemicals that come from the environment or even from their own bodies.
According to researchers, the SOFT devices featuring MOFs display reliable conductivity, enhanced porosity, flexibility and stability to washing. The fabrics are also stable in heat, have good shelf-lives and retain a full-range of utility under humid conditions.
While the technology requires further development before it can be used in state-of-the-art wearable systems, the authors are hopeful that the fabrication method has the potential to be extended into other systems, producing a range of novel, multifunctional e-textiles with highly tunable properties and a host of new applications in wearable and portable devices.

Source: Dartmouth College