domingo, 29 de abril de 2012

USC Researchers Develop Path to Liquid Solar Cells

A USC scientist treats a glass slide with nanocrystals. (Photo/Dietmar Quistorf)

Scientists at USC have developed a potential pathway to cheap, stable solar cells made from nanocrystals so small they can exist as a liquid ink and be painted or printed onto clear surfaces.
The solar nanocrystals are about four nanometers in size – meaning one could fit more than 250 billion on the head of a pin – and float them in a liquid solution, so “like you print a newspaper, you can print solar cells,” said Richard L. Brutchey, assistant professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences.
Brutchey and USC postdoctoral researcher David H. Webber developed a new surface coating for the nanocrystals, which are made of the semiconductor cadmium selenide. Their research is featured as a “hot article” in Dalton Transactions, an international journal for inorganic chemistry.
Liquid nanocrystal solar cells are cheaper to fabricate than available single-crystal silicon wafer solar cells but are not nearly as efficient at converting sunlight to electricity. Brutchey and Webber solved one of the key problems of liquid solar cells: how to create a stable liquid that also conducts electricity.
In the past, organic ligand molecules were attached to the nanocrystals to keep them stable and to prevent them from sticking together. These molecules also insulated the crystals, making the whole thing terrible at conducting electricity.
“That has been a real challenge in this field,” Brutchey said.
Brutchey and Webber discovered a synthetic ligand that not only works well at stabilizing nanocrystals but actually builds tiny bridges connecting the nanocrystals to help transmit current.
With a relatively low-temperature process, the researchers’ method also allows for the possibility that solar cells can be printed onto plastic instead of glass without any issues with melting, resulting in a flexible solar panel that can be shaped to fit anywhere.
As they continue their research, Brutchey said he plans to work on nanocrystals built from materials other than cadmium, which is restricted in commercial applications due to toxicity.
“While the commercialization of this technology is still years away, we see a clear path forward toward integrating this into the next generation of solar cell technologies,” Brutchey said.
The National Science Foundation and USC Dornsife funded the research.

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New Faster and More-Efficient Technique to Generate Single Photons

Georgia Tech graduate student Yaroslav Dudin and professor Alex Kuzmich (l-r) adjust optics as part of research into the production of single photons for use in optical quantum information processing and the study of certain physical systems

Georgia Tech professor Alex Kuzmich and graduate student Yaroslav Dudin have devised a new faster and more-efficient technique based on a phenomenon called Rydberg blockade to generate single photons that can be utilized to explore the disorder and dynamics in specific physical systems and in optical quantum information processing.
Kuzmich and Dudin have been working on quantum information systems that are based on mapping of atomic information onto confined photon pairs. They used Raman scattering technique for this research. However, this technique was inefficient to generate the required number of confined photons for complex systems. To overcome this issue, they have developed the new technique.
The new technique leverages the novel properties of atoms, which have one or more electrons in the Rydberg state. These highly excited atoms have a principal quantum number over 70, demonstrate powerful electromagnetic properties, and interplay strongly with each other. These properties of a Rydberg atom prevent the generation of additional Rydberg atoms within a region of 10-20 µm due to the Rydberg blockade phenomenon. This single Rydberg atom is then transformed to a photon, thus ensuring the generation of one photon from a rubidium ensemble comprising numerous densely-packed atoms.
The researchers produced the Rydberg atom by irradiating a cloud of hundreds of laser-cooled rubidium 87 atoms entangled in an optical lattice, using lasers. The irradiation excited a single atom from the whole ensemble into the Rydberg state. At this state, the Rydberg blockade phenomenon prevents the generation of additional Rydberg atoms by modifying the atomic level energies, thus producing only one Rydberg atom. Since Rydberg atoms demonstrate strong interaction within an area of 10-20 µm, the researchers restricted the volume of their cloud of rubidium atoms, thus ensuring the formation only one Rydberg atom from the ensemble.
Using an additional laser field, the researchers then converted this Rydberg atom into a quantum light field with the same statistical properties of the Rydberg atom. Dudin informed that this new photon source is thousand folds quicker than current systems. The researchers used Rydberg atoms that have a principal quantum number of roughly 100. The next step is to develop a quantum gate in between light fields.

Strongly Interacting Rydberg Excitations of a Cold Atomic Gas. Y. O. Dudin and A. Kuzmich. Science 1217901Published online 19 April 2012 [DOI:10.1126/science.1217901]

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DNA Origami Nanoplate Serves as Smart Lid for Solid-State Nanopore Sensor

This illustration shows how a DNA origami nanoplate with a central aperture can serve as a smart lid or "gatekeeper" for a solid-state nanopore sensor. Researchers at the Technische Universitaet Muenchen have demonstrated that this arrangement can be used to filter biomolecules by size or to "fish" for specific target molecules by placing single-strand DNA receptors inside the aperture as "bait." With further research, they suggest, it might be possible to use such single-molecule sensors as the basis of a novel DNA sequencing system.

Technische Universitaet Muenchen (TUM) researchers have used DNA origami to improve the capabilities of solid-state nanopores. They have combined new capabilities for sensing of single-molecules.
The researchers fitted nanoscale DNA-based nanoscale cover plates on to solid-state nanopores. On these plates, DNA origami was used to form central apertures designed for different "gatekeeper" functions.
Bionanotechnology has enabled single-molecule sensitivity for performing label-free protein screening. Researchers belonging to Prof. Hendrik Dietz's group have been improving control over techniques used for DNA origami, while researchers belonging to Dr. Ulrich Rant's group have been investigating the techniques for solid-state nanopore sensors, wherein a biomolecule is made to pass through a hole, which is of nanometer scale in a thin semiconductor slab. The research groups are collaborating for this study.
The concept involves placing a DNA origami "nanoplate" on top of a solid-state nanopore with a conical taper. The plate is placed over the narrow end of the taper. Controlling the aperture size will enable filtration of the desired size of molecules. Single-stranded DNA receptors are placed in the aperture to act as “bait” and this will enable the detection of "prey" molecules in a sequence-specific manner. This can lead to applications for detecting and screening DNA sequences.
The researchers confirmed the self-assembling ability of specially designed DNA origami nanoplates and their placement on solid-state nanopores. Bait/prey detection of particular target molecules and biomolecule size-based filtering were demonstrated.
The ability of DNA origami gatekeepers to allow the passage of small ions may also be an unwanted leakage current in certain applications. DNA sequencing and other applications may have to face such hurdles.

DNA Origami Gatekeepers for Solid-State Nanopores Ruoshan Wei, Thomas G. Martin, Ulrich Rant, and Hendrik Dietz Angewandte Chemie International Edition on-line, April 4, 2012. DOI: 10.1002/anie.201200688

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NIST Study Proves Thermal Stability of Nanometer-Thick Films for Organic Electronics

A research team from the National Institute of Standards and Technology (NIST) has helped an international research team to verify the stability of an ultrathin membrane using near-edge X-ray absorption fine-structure spectroscopy (NEXAFS).
The ultrathin membrane developed by the international research team can be used as a key component for a new class of flexible, sterilizable organic electronics for use in medical applications. The team is headed by scientists from the University of Tokyo, with members from the Princeton University, Hiroshima University, the Japan Science and Technology Agency, the Max Planck Institute for Solid State Research and Nippon Kayaku, a Tokyo-based company.
The international research team has developed an innovative gate material that enables high-temperature sterilization of organic transistors, thus making them suitable for medical applications such as soft pacemakers and implantable devices. This gate material assembles itself into an ultrathin single layer of tightly packed linear molecules that assemble at a small angle to the surface. The team informed that this self-assembled monolayer (SAM)’s thickness can be down to 2 nm.
Structural measurements of SAM were performed at the NIST low-energy X-ray beam line located at the National Synchrotron Light Source in New York. Samples of the ultrathin film from prior and after heat treatment were tested on the NIST beamline utilizing NEXAFS technique to measure the thermal stability and molecular orientation of the film.
The NEXAFS technique is capable of detecting chemical bonds at the surface and in the interior of the sample. For example, it can show the disparity between a single carbon bond and a double carbon bond within a molecule. The NEXAFS measurements proved that the SAM ultrathin films were able to maintain their integrity and stability even at temperatures above 150°C.

K. Kuribara, H. Wang, N. Uchiyama, K. Fukuda, T. Yokota, U. Zschieschang, C. Jaye, D. Fischer, H. Klauk, T. Yamamoto, K. Takimiya, M. Ikeda, H. Kuwabara, T. Sekitani, Y-L. Loo and T. Someya. Organic transistors with high thermal stability for medical applicationsNature Communications. 3, 723. Mar. 6, 2012. doi:10.1038/ncomms1721

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Nanotecnologia en ...biomasa.. de pescado.. diak!

Economic and environmental balance of the fish looked. The fishing activities and to firm or industry is concerned. The natural growth rate of biomass power and creativity depends on size and scope of the firm. If the growth rates of fish using natural biological and nano-technology is more and this situation persists for a long time, fish populations are faced with extinction. 

 Hence in order to achieve this balance, the environmental sustainability of biomass was investigated. Sustainable fisheries and technical functions and features of the natural and biological function depends on growth. Technical function as a multiplier of the product of fishing effort alive in mass and growth rate assumed by the logistic function to show the balance of economic and environmental sustainability of our investigation. Through balancing the relationship between behavior and the amount of fishing effort using nanotechnology, and we determine the average yield and efficiency in the end we get caught. The average rate of return than the amount of fishing effort and efficiency derived from the behavior of the final amount of fishing effort than is available. 

Even, the UK, is in this topic and organiced a full conference of this, "And, it looks at policy and topics as varied as the grid (including a session on intermittency); sustainable transport; energy storage (with a second session on the topic specifically looking at nanotechnology); renewable energy growth in China and the Far East; sessions for the farming community, and for communities/co-operatives with – or planning – renewable assets; islands and ‘energy islands’; industry perspectives on financing; frameworks for support – and tapping into Europe; Scotland’s new power landscape; public perception"

Balance Economic, Environmental and Renewable Biomass Using Nanotechnology. (2011). Journal of Applied Sciences Research7(11), 474-479.

jueves, 26 de abril de 2012

Can Water Float on Oil?

The tensile strength of interfaces between air/liquid and immiscible liquid/liquid systems has been the driving force in nature and industrial processes such as wetting/dewetting and coating. Despite its small magnitude, interfacial tension can be the dominant force in capillary tubes, microgravity conditions, and nanofluids. In addition to capillary rise, the surface tension can work against gravity and support a solid body floating in water surface, which has been noticed as early as 350 BC by Aristotle. In nature, insects such as water striders rely on surface tension to walk on water. Experimentally, small spherical particles, few millimeters in diameter, have been reported as floating on the air/water interface. In contrast to rigid bodies, a fluid droplet at surface of another fluid has three deformable interfaces and variable contact angles. The equilibrium of three interface tensions at the contact line, if it exists, results in an unique combination of three contact angles, which form a Neumann’s triangle.The interfacial interaction between three fluids has been investigated for an oil droplet spreading on water surface by Langmuir and for a fluid droplet at the interface between two fluids by Princen.
More recently, numerical methods were applied to identify the shape of such droplets. In these instances, the liquid droplet is less dense than the supporting liquid, and gravity always plays a stabilizing role on the system.
In this work a numerical model was developed from the Young−Laplace equation on three interfaces (water/oil, water/air, and oil/air) to predict the theoretical equilibration conditions. The model was verified successfully with an oil/water system. The stability of the floating droplet depends on the combination of three interface tensions, oil density, and water droplet volume. For practical purposes, however, the equilibrium contact angle has to be greater than 5° so the water droplet can effectively float. This result has significant applications for biodegrading oil wastes.

Can Water Float on Oil?
Chi M. Phan,* Benjamin Allen, Luke B. Peters, Thu N. Le, and Moses O. Tade
Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth WA 6845, Australia

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Sponging up oil spills: Nanosponges soak up oil again and again

En una investigación encabezada por Mauricio Terrones (Penn State) y desarrollada hace algún tiempo en una colaboración entre Rice University e IPICYT, se han obtenido nanoesponjas de nanotubos de carbono capaces de absorber hasta 1000 veces su peso en hidrocarburos. Una excelente aplicación para la remoción de contaminantes durante un derrame petrolero, sin duda.

Mas información aquí:

Sponging up oil spills: Nanosponges soak up oil again and again

Self-Assembling Highly Conductive Plastic Nanofibers

Researchers from CNRS and the Université de Strasbourg, headed by Nicolas Giuseppone and Bernard Doudin, have succeeded in making highly conductive plastic fibers that are only several nanometers thick. These nanowires, for which CNRS has filed a patent, "self-assemble" when triggered by a flash of light. Inexpensive and easy to handle, unlike carbon nanotubes, they combine the advantages of the two materials currently used to conduct electric current: metals and plastic organic polymers. In fact, their remarkable electrical properties are similar to those of metals. 

In collaboration with Doudin's team, the researchers then studied the electrical properties of these nanofibers in detail. This time, they placed their molecules in contact with an electronic microcircuit comprising gold electrodes spaced 100 nm apart. They then applied an electric field between these electrodes.
Their first important finding was that, when triggered by a flash of light, the fibers self-assemble solely between the electrodes. The second surprising result was that these structures, which are as light and flexible as plastics, turn out to be capable of transporting extraordinary current densities, above 2.10^6 Amperes per square centimeter (, approaching those of copper wire. In addition, they have very low interface resistance with metals (6) : 10,000 times below that of the best organic polymers.
The researchers now hope to demonstrate that their fibers can be used industrially in miniaturized electronic devices such as flexible screens, solar cells, transistors, printed nanocircuits, etc.

Complete article in here

Vina Faramarzi, Frédéric Niess, Emilie Moulin, Mounir Maaloum, Jean-François Dayen, Jean-Baptiste Beaufrand, Silvia Zanettini, Bernard Doudin, Nicolas Giuseppone. Light-triggered self-construction of supramolecular organic nanowires as metallic interconnects. Nature Chemistry, 2012; DOI: 10.1038/NCHEM.1332

miércoles, 25 de abril de 2012

New plastic bleeds and heals like human skin

A new plastic demonstrated to the American Chemical Society on Monday not only professes t...
A new plastic demonstrated to the American Chemical Society on Monday purports to be the first self-healing material to incorporate a damage-reporting mechanism, almost akin to the bleeding of human skin. "Our new plastic tries to mimic nature, issuing a red signal when damaged and then renewing itself when exposed to visible light, temperature or pH changes," said Professor Marek W. Urban, Ph.D of the University of Southern Mississippi. Urban's plastic contains molecular bridges that span the polymer chains that comprise the plastic. Should the plastic become damaged, these bridges break down; but when exposed to light (or a temperature or acidic vapor) these linkages are able to repair themselves. But additionally, Urban has rigged the bridges to change color - to red - when such damage occurs, with the color change fading away when the material repairs - essentially heals - itself. Such a material has obvious benefits when applied to consumer goods, such as laptops and mobile phones. Dropping the device would result in hairline cracks turning red, highlighting a need for repair (whereupon you need only expose the thing to intense light). But Urban also foresees heavier-duty applications: car fenders, aircraft components and even battlefield weapons systems among them (Urban has received U.S. Department of Defense funding for the research).
source: American Chemical Society

Reusable oil-absorbing nanosponges could soak up oil spills

This carbon nanotube sponge can hold more than 100 times its weight in oil, which can be s...
      Now, by adding boron to carbon while growing nanotubes, researchers have developed a nanosponge with the ability to absorb oil spilled in water. Remarkably, the material is able to achieve this feat repeatedly and is also electrically conductive and can be manipulated with magnets. While multiwalled carbon nanotubes grown on a substrate via chemical vapor disposition form standing up without any real connections to their neighbors, the researchers found that adding a dash of boron to the nanotube production process puts kinks and elbows into them as they grow and promotes the formation of covalent bonds. This gives the nanosponges, which are 99% air, an elastic property that is retained even after 10,000 compressions in the lab. The sponges are both superhydrophobic - meaning they repel water allowing them to float extremely well – and oleophilic – meaning they have a strong affinity for oils. These dual properties give the material the ability to soak up oil floating on the surface of water. The potential for the material in soaking up oil spills at sea is obvious. But the material has the added ability to be used repeatedly so, after soaking up oil, it could be wrung out and reused. The oil can also be burned off while in the sponge, which can then be reused again. "These samples can be made pretty large and can be easily scaled up,” says Rice graduate student Daniel Hashim, holding a half-inch square block of billions of nanotubes. “They’re super-low density, so the available volume is large. That’s why the uptake of oil can be so high.” Hashim says the sponges can absorb more than a hundred times their weight in oil. He is working on ways to weld large sheets of the nanosponges together so they could be used to mop up oil spills. However, the researchers believe environmental cleanup applications are just the tip of the iceberg for the material. “For example, we could use these materials to make more efficient and lighter batteries. We could use them as scaffolds for bone-tissue regeneration. We even could impregnate the nanotube sponge with polymers to fabricate robust and light composites for the automobile and plane industries,” says Mauricio Terrones, a professor of physics, materials science and engineering at Penn State University. Hashim adds that the nanosponges could also be used as membranes for filtration applications. Researchers from Rice University and Penn State University developed the material, working with colleagues in labs around the U.S., and in Spain, Belgium and Japan. Hashim is lead author of the paper detailing the discovery, which appears online in Nature’s open-access journal Scientific Reports.
Hashim shows off some of the nanosponge’s remarkable properties in the following video.

NT sponge soaks up oil

Buckyballs diet nearly doubles rats lifespan

A recent study French has shown that a diet of  buckyballs dissolved in olive extends life...

A recent French study looking for chronic toxicity resulting from ingesting buckyballs dissolved in olive oil found that 10 month old rats who ingested the human equivalent of a tenth of a gram of C-60 buckyballs (which in technical grades cost less than US$10/gram) several times a week showed extended lifespans instead of toxic effects. All C-60-treated rats survived to at least 59 months, with the oldest surviving to 66 months. The control group lived for periods ranging from 17 months to 37 months, while an additional group fed only the extra olive oil lived for periods of 36 to 57 months. For the curious, the olive oil dosage was equivalent to a person adding about eight tablespoons of uncooked olive oil to their daily diet without compensating for the additional calories. Similar results have been reported for mammals held in a state of semi-starvation, but that is obviously not a pleasant lifestyle. All fullerenes are susceptible to clumping when dissolved in oil, so the preparation of the olive-oil/C-60 solution is rather lengthy. In these tests, 50 mg of C-60 buckyballs were added to 10 ml of virgin olive oil. These were stirred for two weeks at ambient temperatures with no incident light. Following the stirring, the solutions were centrifuged at 5,000 g for an hour. The fluid was separated from the precipitate, and was then passed through a 0.25 micron filter. The resulting liquid contained 0.8 mg/ml of C-60 buckyballs. The results beg the question - what is going on here? Is the life extension just for those lucky rats again, or is there a mechanism that might transfer over to humans? The study was aimed at discovering if a diet of buckyballs has any toxic effects, and the good news is that no toxicity was found. The buckyballs did move throughout the body (including the brain and central nervous system), and even enter individual cells. The ingested C-60 had an elimination half-life from blood of about 10 hours, so was essentially fully eliminated from the body within two days. It is not clear from the report if the C-60 was eliminated from intracellular fluid on that time scale. Specific studies of the effect of C-60 buckyballs on oxidative stress in the rats were performed by studying the effects of carbon tetrachloride (CCl4) injection. Carbon tetrachloride is well known to be poisonous to rats, being highly hepatotoxic (toxic to the liver). It is also associated with delirium and intoxication such as is experienced in the abuse of solvents. Rats which had been pretreated by water, by olive oil, and by olive oil containing C-60 buckyballs all showed typical signs of intoxication within a few minutes of CCl4 injection. However, while intoxication persisted in the water and olive oil groups for 24 hours, the olive oil and C-60 group emerged from intoxication after only five hours. In rats experiencing the pretreatment, but unexposed to carbon tetrachloride, autopsy revealed essentially normal livers. In those given a CCl4 injection, however, the livers from rats pretreated with water or olive oil showed important damage - a great deal of inflammation as well as large necrotic areas (dying or dead tissue). In contrast, the livers from rats pretreated with olive oil and C-60 buckyballs showed little damage or CCl4-induced cell death. Biochemical markers of liver damage showed far less elevation in the rats pretreated with olive oil and C-60. It does appear there is a real physiological effect on metabolic processes, and that oxidative stress in particular is significantly reduced in rats by chronic oral ingestion of an olive oil/C-60 solution. As oxidative stress is one of the factors usually associated with aging, there may well be a reasonable mechanism for the lifespan extension, especially if excess oxidation within individual cells is prevented by intracellular buckyballs. Will people react to a treatment of this sort with lifespans of 180-200 years? Only time will tell.

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Micropatterning of Bioactive Glass Nanoparticles on Chitosan Membranes for Spatial Controlled Biomineralization

normal.img-000.jpgIn recent years, the biomaterials field has witnessed the rise of a third generation of materials able to stimulate specific cellular responses.Exposed to the right surface chemistry and topography, cells can adhere, proliferate, and differentiate.Microcontact printing (μCP) of biologically relevant ligands using a soft poly(dimethylsiloxane) PDMS stamp is the most common technique to generate specific patterns with different and well-defined chemistries. Patterns of proteins, molecules, polymers, nanoparticles, self-assembled monolayers, colloids, and metals have been reported.
Different methods can be applied to engineer culture substrates for guiding cellular responses with spatial control. Bioactive glass has been demonstrated to have a beneficial effect in bone regeneration, skin, articular regeneration, and angiogenesis applications as it binds to both bone and soft tissue.
Bioactive glass has been mainly applied in orthopedic and dental areas, since it promotes deposition of apatite under physiological conditions. A few works have reported the fabrication of substrates with spatial control of biomineralization. 
This team has been developed bioactive glass nanoparticles (BG-NPs) capable of inducing apatite precipitation upon immersion in simulated body fluid (SBF) were patterned on free-standing chitosan membranes by microcontact printing using a poly(dimethylsiloxane) (PDMS) stamp inked in a BG-NPs pad. Formation of the patterns was characterized by scanning electron microscopy (SEM). Mineralization of the bioactive glass patterns was induced in vitro by soaking the samples in SBF over different time points up to 7 days. The confined apatite deposition in the patterned regions with diameters of 50 μm was confirmed by Fouriertransformed infrared spectroscopy (FTIR), energy-dispersive X-ray (EDX) analysis, and SEM. In vitro tests confirmed the preferential attachment and proliferation of L929 cells to the areas printed with BG-NPs of the membranes. This approach permits one to spatially control the properties of biomaterials at the microlevel and could be potentially used in guided tissue regeneration for skin, vascular, articular, and bone tissue engineering and in cellular cocultures or to develop substrates able to confine cells in regions with controlled geometry at the cell’s length scale.

Micropatterning of Bioactive Glass Nanoparticles on Chitosan Membranes for Spatial Controlled Biomineralization
Gisela M. Luz, Luciano Boesel, Aranzazu del Campo, ́and Joao F. Mano 
3B’s Research Group-Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Caldas das Taipas, Portugal
ICVS/3B’s-PT Government Associated Laboratory, Braga/Guimaraes, Portugal 
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

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lunes, 23 de abril de 2012

Papel a Súper Papel

Cientí­ficos del Istituto Italiano di Tecnologia en Genoa, Italia, han desarrollado un spray de nanoparticulas puede convertir papel en súper papel, haciendolo a prueba de agua, antimicrobial, magnético y probablemente muy caro. El proceso de cubrir cualquier fibra celulosa, como el papel o la tela, con un revestimiento reactivo. Las moléculas de la fibra se combinan con la solución de nanoparticulas, creando una matiz de polímero.

La fibra celulosa es humedecida con una solución acrílica que contiene nanoparticulas de mangnaneso, que son magnéticas. Cuándo se humedecen, la combinación forma un nano-escudo alrededor de cada fibra individual, haciendo que la fibra se repelente de agua.

Para las propiedades magnéticas, los científicos pueden cambiar la composición de las nanoprtículas para aumentar o disminuir su respuesta magnética, además de poder agregar nuevos atributos. Si se le agrega plata coloidal, puede ser antibacterial.

Además del pequeño nano-escudo formado alrededor de cada fibra, las porpiedades del papel no cambian; se puede imprimir en el, doblarlo, etc. El súper papel puede tener muchas aplicaciones, desde empaquetamiento de comida hasta documentos médicos para asegurar la pureza, de acuerdo con Roberto Cingolani, científico director del IIT.

El supepapel es descrito con más detalle en el Journal of Materials Chemistry.


Direct Observation of Nanoparticle Cancer Cell Nucleus Interactions

The nucleus is the most important organelle in the growth, proliferation, and apoptosis of a cell. Controlling the processes governed by the nucleus has been a primary goal for nuclear-targeted cancer therapy. Conventionally, viral vectors are used to deliver drugs to cell nuclei, but a drawback is the resulting immunogenic response.

Recently, nuclear targeting by peptide-modified gold NPs has seen some success and shown improved anticancer efficacy; however, the mechanism responsible for the increased cell death is unknown because no nanoscale direct visualization of how the NPs affected the nucleus was shown.

Nucleolin is the most abundant nucleolar phosphoprotein in the nucleus of normal cells but in metastatic and rapidly dividing cells is overexpressed in the cytoplasm and translocated to the cell membrane. The trafficking ability of nucleolin has been implicated in transporting anticancer ligands from the cell surface to the nucleus.

This report includes the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultrafast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This
newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy.

Duncan Hieu M. Dam, Jung Heon Lee, Patrick N. Sisco, Dick T. Co, Ming Zhang, Michael R. Wasielewski, and Teri W. Odom 

Department of Chemistry and Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States, Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, Illinois 60611, United States, and School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, South Korea 

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Nanocrystal-Coated Fibers Might Reduce Wasted Energy

Researchers are developing a technique that uses nanotechnology to harvest energy from hot pipes or engine components to potentially recover energy wasted in factories, power plants and cars.

"The ugly truth is that 58 percent of the energy generated in the United States is wasted as heat," said Yue Wu, a Purdue University assistant professor of chemical engineering. "If we could get just 10 percent back that would allow us to reduce energy consumption and power plant emissions considerably."

Researchers have coated glass fibers with a new "thermoelectric" material they developed. When thermoelectric materials are heated on one side electrons flow to the cooler side, generating an electrical current.

Coated fibers also could be used to create a solid-state cooling technology that does not require compressors and chemical refrigerants. The fibers might be woven into a fabric to make cooling garments.
The glass fibers are dipped in a solution containing nanocrystals of lead telluride and then exposed to heat in a process called annealing to fuse the crystals together.

Complete article in here

Purdue University (2012, April 17). Nanocrystal-coated fibers might reduce wasted energy. ScienceDaily. Retrieved April 23, 2012, from­ /releases/2012/04/120417143857.htm

domingo, 22 de abril de 2012

Nanocrystal-coated fibers might reduce wasted energy

Flexible Nanocrystal-Coated Glass Fibers for High-Performance Thermoelectric Energy Harvesting
By Itza Montforte, Web Writer

Recent efforts on the development of nanostructured thermoelectric materials from nanowires and nanocrystals show the comparable or superior performance to the bulk crystals possessing the same chemical compositions because of the dramatically reduced thermal conductivity due to phonon scattering at nanoscale surface and interface. 
Up to date, the majority of the thermoelectric devices made from these inorganic nanostructures are fabricated into rigid configuration. The explorations of truly flexible composite-based flexible thermoelectric devices have, thus far achieved much less progress, which in principle could significantly benefit the conversion of waste heat into electricity or the solid-state cooling by applying the devices to any kind of objects with any kind of shapes. 

This investigation by the Purdue University is the development of a techinque that uses nanotechnology to harvest energy from hot pipes or engine components to potentially recover energy wasted in factories, power plants and cars. 
Researchers have coated glass fibers with a new thermoelectric material developed, when this thermoelectric materials are heated on one side, electron flow to the cooler side generating and electrical current, thus, diminishing the wasted energy. Coated fibers also could be used to create a solid-state cooling technology that does not require compressors or chemical refrigerants. 

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Storing Energy

Nature's billion-year-old battery key to storing energy
By Itza Montforte Noguez, Web Writer.

Base on the enzimatic action which can store energy from seconds to hours, a new study was published in the Journal of The American Chemical Society which demostrates that it is possible to extend the length of time a battery can store, bringin us one step closer to clean energy.

The research at Concordia University by the Department of physics and associates reaches toward an enzyme found in bacteria that is crucial for capturing solar energy in a similar way to what a battery does.    László Kálamán, an associate professor showed that although energy in nature is used immediately, by adding different molecules the lifespan of its electrical potencial is extended.

This research is also inpired by the billion-year-old natural batery, the photosynthesis plants use. this process, although very difficult to repruduce, is the key to storying and using solar clean energy in a way never seen before.

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New nanoparticle technology cuts water use, energy costs

Nuclear and coal power plants are some of the thirstiest machines on earth. The turbines that spin inside of them to generate electricity require tons and tons of steam, and all of that water has to come from somewhere.

Recent studies have estimated that roughly two-fifths of the nation’s freshwater withdrawals and three percent of overall freshwater consumption goes to supplying the steam generators at large power stations in the United States. In order to cut down on the enormous quantities of water required to operate these plants, scientists have begun to look for new technologies that could improve their efficiency and reduce the demand for water.
As part of a larger consortium involving partners from several energy companies, universities, and government agencies, researchers at the U.S. Department of Energy’s Argonne National Laboratory are developing a special class of nanoparticles that partially melt as steam evaporates from a plant’s cooling towers, absorbing a significant percentage of the diffused heat in the system.
In order to operate, electrical plants use a cycle that uses partially condensed high-temperature steam to turn a large .  During generation, a significant quantity of this steam is lost due to evaporation. “In every cycle, there’s a significant amount of water that we can’t recapture,” said Argonne materials scientist Dileep Singh, who is working to develop the specialized nanoparticles.
The nanoparticles are based on what is known as a “core-shell” configuration, in which a solid outer coat protects an inner layer that can melt above a certain temperature. Once dispersed in the plant’s water supply, the nanoparticles are able to absorb heat during the thermal cycle. After partially melting, the particles travel to the cooling tower where they resolidify. The system is closed and designed to ensure against leakage of the plant’s water or steam into the environment.
At the molecular level, Singh and his colleagues are especially concerned with the surface of the nanoparticles, as the chemistry at the boundary between the metal and the water determines how much heat the particles can take up. “We’re experimenting with looking at the bonding between the particles and the water molecules,” he said.
“What we really want to know is how much heat we can pick up given a constant amount of water to cool the system,” he added. “Environmentally responsible energy growth involves worrying about how you manage your water resources.”
The vast quantities of water that are needed to operate these facilities will necessitate the mass production of the nanoparticles once they are commercially developed, a fact that could potentially complicate the research and development process, said Argonne associate division director Thomas Ewing. “As we begin lab testing, we need to keep in mind the costs and issues associated with making this work in a real live power plant,” he said. “There are lots of tradeoffs to take into account.”
According to Ewing, Argonne is working with the Electric Power Research Institute and other partners to move this basic technology quickly through the developmental pipeline. Initial plans call for the demonstration of proof of concept to commence this year and full-scale commercial deployment to begin in four years. “It’s practically unheard of for industry to seek to deploy a new technology so quickly,” Ewing said. “However, water consumption is a major issue that limits the expansion of power. If we want to solve the energy crisis, we’ll have to move boldly.”
 More information: here

Sulfur in every pore: Improved batteries with carbon nanoparticles

From smartphones to e-bikes, the number of mobile electronic devices is steadily growing around the world. As a result, there is an increased need for batteries that are small and light, yet powerful. As the potential for the further improvement of lithium-ion batteries is nearly exhausted, experts are now turning to a new and promising power storage device: lithium-sulfur batteries.

In an important step toward the further development of this type of battery, a team led by Professor Thomas Bein of LMU Munich and Linda Nazar of Waterloo University in Canada has developed porous carbon nanoparticles that utilize sulfur molecules to achieve the greatest possible efficiency.

In prototypes of the lithium-sulfur battery, lithium ions are exchanged between lithium- and sulfur-carbon electrodes. The sulfur plays a special role in this system: Under optimal circumstances, it can absorb two lithium ions per sulfur atom. It is therefore an excellent energy storage material due to its low weight. At the same time, sulfur is a poor conductor, meaning that electrons can only be transported with great difficulty during charging and discharging. To improve this battery's design the scientists at Nanosystems Initiative Munich (NIM) strive to generate sulfur phases with the greatest possible interface area for electron transfer by coupling them with a nanostructured conductive material.

To this end, Thomas Bein and his team at NIM first developed a network of porous carbon nanoparticles. The nanoparticles have 3- to 6-nanometer wide pores, allowing the sulfur to be evenly distributed. In this way, almost all of the sulfur atoms are available to accept lithium ions. At the same time they are also located close to the conductive carbon.

"The sulfur is very accessible electrically in these novel and highly porous carbon nanoparticles and is stabilized so that we can achieve a high initial capacity of 1200 mAh/g and good cycle stability," explains Thomas Bein. "Our results underscore the significance of nano-morphology for the performance of new energy storageconcepts."

The carbon structure also reduces the so-called polysulfide problem. Polysulfides form as intermediate products of the electrochemical processes and can have a negative impact on the charging and discharging of the battery. The carbon network binds the polysulfides, however, until their conversion to the desired dilithium sulfide is achieved. The scientists were also able to coat the carbon material with a thin layer of silicon oxide which protects against polysulfides without reducing conductivity.

Incidentally, the scientists have also set a record with their new material: According to the latest data, their material has the largest internal pore volume (2.32 cm3/g) of all mesoporous carbon nanoparticles, and an extremely large surface area of 2445 m2/g. This corresponds roughly to an object with the volume of a sugar cube and the surface of ten tennis courts. Large surface areas like this might soon be hidden inside our batteries.
More information: "Spherical Ordered Mesoporous Carbon Nanoparticles with Extremely High Porosity for Lithium-Sulfur Batteries". Jörg Schuster, Guang He, Benjamin Mandlmeier, Taeeun Yim, Kyu Tae Lee, Thomas Bein and Linda F. Nazar.Angewandte Chemie, 1 MAR 2012.

Stable electrodes for improving printed electronics

Imagine owning a television with the thickness and weight of a sheet of paper. It will be possible, someday, thanks to the growing industry of printed electronics. The process, which allows manufacturers to literally print or roll materials onto surfaces to produce an electronically functional device, is already used in organic solar cells and organic light-emitting diodes (OLEDs) that form the displays of cellphones.

Although this emerging technology is expected to grow by tens of billions of dollars over the next 10 years, one challenge is in manufacturing at low cost in ambient conditions. In order to create light or energy by injecting or collecting electrons, printed electronics require conductors, usually calcium, magnesium or lithium, with a low-work function. These metals are chemically very reactive. They oxidize and stop working if exposed to oxygen and moisture. This is why electronics in solar cells and TVs, for example, must be covered with a rigid, thick barrier such as glass or expensive encapsulation layers.
However, in new findings published in the journal Science, Georgia Tech researchers have introduced what appears to be a universal technique to reduce the work function of a conductor. They spread a very thin layer of a polymer, approximately one to 10nanometers thick, on the conductor's surface to create a strong surface dipole. The interaction turns air-stable conductors into efficient, low-work function electrodes.
The commercially available polymers can be easily processed from dilute solutions in solvents such as water and methoxyethanol.
"These polymers are inexpensive, environmentally friendly and compatible with existent roll-to-roll mass production techniques," said Bernard Kippelen, director of Georgia Tech's Center for Organic Photonics and Electronics (COPE). "Replacing the reactive metals with stable conductors, including conducting polymers, completely changes the requirements of how electronics are manufactured and protected. Their use can pave the way for lower cost and more flexible devices."
To illustrate the new method, Kippelen and his peers evaluated the polymers' performance in organic thin-film transistors and OLEDs. They've also built a prototype: the first-ever, completely plastic solar cell.
"The polymer modifier reduces the work function in a wide range of conductors, including silver, gold and aluminum," noted Seth Marder, associate director of COPE and professor in the School of Chemistry and Biochemistry. "The process is also effective in transparent metal-oxides and graphene."
 more information: here

Scientists make nontoxic, bendable nanosheets

Cornell materials scientists have developed an inexpensive, environmentally friendly way of synthesizing oxide crystal sheets, just nanometers thick, which have useful properties for electronics and alternative energy applications.

The work, led by Richard Robinson, assistant professor of materials science and engineering, is featured on the cover of the April 7  (Vol. 22, No. 13).
The millimeter-length, 20 nanometer-thick sodium-cobalt oxide crystals were derived through a novel method that combined a traditional sol-gel synthesis with an electric field-induced kinetic de-mixing step. It was this second step that led to the breakthrough of a bottom-up synthesis method through which tens of thousands of nanosheets self-assemble into a pellet.
The material has fascinating properties, Robinson said, including high thermoelectric power, high electrical conductivity, superconductivity and potential as a  in  batteries.
Usually oxide materials, like a ceramic coffee mug, aren't electrically conductive; they're insulating, Robinson said. Since the material is a conductive oxide, it can be used in thermoelectric devices to convert waste heat into power. Now that the researchers have made nanosheets, they expect the material's thermoelectric efficiency to improve, enabling the creation of more efficient alternative energy thermoelectric devices.
The nanosheets also show the ability to bend, sometimes up to 180 degrees, Robinson added. This is unusual for ceramics, which are normally brittle.
The material is based on common, abundant elements (sodium, cobalt and oxygen), without toxic elements, such as tellurium, that are normally used in .
The paper's co-authors are graduate students Mahmut Aksit and David Toledo. The work was supported by the National Science Foundation and the U.S. Department of Energy, through the Energy Materials Center at Cornell (EMC2).

New design for nanoparticles that absorb low-energy light, emit high-energy light may find use in biological imaging

The light that a luminescent particle emits is usually less energetic than the light that it absorbs. Some applications require the emitted light to be more energetic, but this so-called upconversion process has been observed in only a small handful of materials. Xiaogang Liu at the A*STAR Institute of Materials Research and Engineering and co-workers have now succeeded in expanding the list of upconversion materials, easing the path to new applications.

Traditional upconversion  are distinguished by their evenly-spaced or ‘ladder-like’ energy levels which their internal electrons can take on. The even spacings allow an electron to be promoted up in energy many times consecutively, by absorbing many photons of the same color. When an electron that has been promoted to a high energy finally relaxes back to the lowest-energy state, it emits a photon which is more energetic than the photons that excited it to begin with.
Nanoparticles doped with elements from the lanthanide group of the periodic table are capable of upconversion, and are useful for biological imaging because their high-energy emission can be clearly distinguished from background noise. However, only three elements from the lanthanide series are efficient at upconversion: erbium, thulium, and holmium. This list is so short because of the simultaneous requirements that an upconversion particle exhibit a ladder-like electronic energy structure, and also efficient emission.
Liu and colleagues solved this problem by using different lanthanides to perform different stages of the upconversion process. Sensitizer elements absorb incident, and transfer the absorbed energy to nearby accumulators, whose electrons rise to high energy levels. Then, the  stored in accumulators transfers by hopping through many migrators, until an activator is reached. Finally, the activator releases a high-energy photon.
By assigning different elements to each of these four functions, the researchers were able to ease the requirements on any individual element. In addition, unwanted interactions among different elements were avoided by separating them spatially inside a single spherical nanoparticle that has sensitizers and accumulators in the core, activators in the shell and migrators in both the core and the shell.
This design allowed Liu and his team to observe a spectrum of colors from the upconverted emission of europium, terbium, dysprosium and samarium (see image). The same approach may also allow other elements to emit efficiently. “Our results may lead to advances in ultrasensitive biodetection,” says Liu, “and should inspire more researchers to work in this field.”

More information:  Wang, F. et al. Tuning upconversion through energy migration in core–shell nanoparticles. Nature Materials 10, 968–973 (2011).

Imaging complex domain wall structures in magnetic nanostripes

Researchers from the NIST Center for Nanoscale Science and Technology and Massachusetts Institute of Technology have used the scanning electron microscopy with polarization analysis (SEMPA) technique to provide the first direct images of the magnetic structure of highly twisted domain walls in patterned thin film magnetic nanowires.

This imaging method allows these complex and delicate structures to be easily compared to magnetic simulations, a useful step for developing technology that uses domain walls in nanowires for high density data storage and for field or current driven magnetic logic.
A typical domain wall separates two opposite regions of magnetization, making it a “180° wall”. The researchers showed that several 180° walls could be injected into a nanowire, where they either annihilated each other or they combined to form complex walls in which the magnetization rotated by up to 540°. The 360° walls were of particular interest, since their magnetic behavior is dramatically different from the 180° walls currently used in prototype memory and logic devices.
The researchers believe that, in addition to providing information about how 180° walls interact in domain wall-based nanowire memories, this work may lead to new magneto-electronic applications using 360° domain walls, such as manipulating bits using highly localized magnetic fields in magnetic logic circuits

For more info: here

New microscope captures nanoscale structures in dazzling 3D

A new x-ray microscope probes the inner intricacies of materials smaller than human cells and creates unparalleled high-resolution 3D images. By integrating unique automatic calibrations, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory are able to capture and combine thousands of images with greater speed and precision than any other microscope. The direct observation of structures spanning 25 nanometers will offer fundamental advances in many fields, including energy research, environmental sciences, biology, and national defense.

This innovative full field transmission x-ray microscope (TXM), funded by the American Reinvestment and Recovery Act, was developed and commissioned at Brookhaven Lab’s National Synchrotron Light Source (NSLS), which provides the x-ray source needed to capture images on the nanoscale. A new paper published in the April 2012 Applied Physics Letters details the experimental success of a breakthrough system that rapidly combines 2D images taken from every angle to form digital 3D constructs.
“We can actually see the internal 3D structure of materials at the nanoscale,” said Brookhaven physicist Jun Wang, lead author of the paper and head of the team that first proposed this TXM. “The device works beautifully, and it overcomes several major obstacles for x-ray microscopes. We’re excited to see the way this technology will push research.”
Wang’s team examined, for example, a 20-micrometer electrode from a lithium-ion battery – as thin around as a human hair. The internal interaction of pores and particles determines the energy performance of the battery, and examining that activity requires precise knowledge of the nanoscale structure.

This 3D reconstruction of a lithium-ion battery electrode, composed of 1,441 individual images captured and aligned by the TXM, reveals nano-scale structural details to help guide future energy research.

 more information: here