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Schmidt A.,Center for NanoScience | Bein T.,Center for NanoScience
Nano Letters | Year: 2013

We investigated uptake and individual endosome lysis events in fibroblast, normal, and carcinoma cell lines using a colloidal mesoporous silica (CMS) nanoparticle (NP)-based reporter system with a covalently attached photosensitizer. Endosome lysis was induced through the activation of protoporphyrin IX (PpIX). Surprisingly, this release-on-demand system resulted in more broadly distributed lysis times than expected, particularly for Renca, a renal carcinoma cell line. An analysis of the NP load per endosome, endosome size, and uptake characteristics indicate that Renca cells not only take up a lower amount of NPs in comparison with the fibroblast cells but also have larger endosomes and a lower NP load per endosome. We then created a stochastic model detailing steps downstream of uptake to understand how much factors that cannot be directly measured, such as variations in the PpIX load per NP, affect the lysis time distributions. Model results indicate that the distributions are primarily determined by the endosome properties, rather than variations across NPs. © 2013 American Chemical Society.


(Phys.org)—A team of researchers with the National Center for Nanoscience and Technology and Beihang University, both in China, has developed a biodegradable triboelectric nanogenerator for use as a life-time designed implantable power source in an animal body. In their paper published in the journal Science Advances the team describes their nanogenerator, its possible uses and the ways it can be tweaked for use in different applications.


News Article | March 7, 2016
Site: www.cemag.us

A team of researchers with the National Center for Nanoscience and Technology and Beihang University, both in China, has developed a biodegradable triboelectric nanogenerator for use as a lifetime-designed implantable power source in an animal body. In their paper published in the journal Science Advances the team describes their nanogenerator, its possible uses and the ways it can be tweaked for use in different applications. Scientists have been working on developing internal devices for many years and several have been created and are now in use inside human patients — the pacemaker is the most well-known. But to date, all such devices suffer from the same deficit — none run using an internal power source, which means they must rely on batteries. While batteries are convenient, they tend to run out of power, which means a patient must undergo a surgical procedure to have them replaced and surgical procedures by their very nature are risky because they open the body to possible infection. A better way, as the researchers with this new effort point out, would be to have implantable devices running off a power source that is generated inside the body, such as capturing heat or making use of the movement of blood. The new device they have created generates electricity via triboelectricity — where electricity is generated when two materials touch each other and then separate, one of the common ways that static electricity comes about. The new device consists of two strips of multi-layered material. One of the strips has a flat film outer layer, the other strip has nanometer sized protruding rods on its exterior — when the two strips meet and then pull away, a tiny amount of electricity is created. The layers are kept apart by blocks of a biodegradable polymer; electricity is generated as parts of the body moves in a way that causes the two strips to come into contact and then to pull apart — over and over. Testing of the device showed it was capable of producing a power density of 32.6 milliwatts per square meter, which they found was enough to power a neuron-stimulation device used to steer the way neurons grow. The team claims their device has paved the way for a new generation of internal devices, noting that not only is it biodegradable, but it can be tuned to self-destruct over days, months or even years. Similar devices, they note, could be made to work by utilizing the power from a person breathing or from their heart beating.


News Article | May 28, 2016
Site: www.techtimes.com

For the first time, scientists have merged energy-harvesting solar cell and nanogenerator technologies to convert wind power into electricity — and potentially power the so-called Internet of Things (IoT). IoT is aimed at making cities “smarter” through connecting an expansive network of small communications devices for greater efficiency, said researchers from the Georgia Institute of Technology in the United States and National Center for Nanoscience and Technology in Beijing, China. This goal, however, requires plenty of energy, which could increase global fossil fuel dependence. The challenge is to have sustainable energy generation in cities — with none of the space-intensive wind turbines, for instance — where the devices will be positioned. Ya Yang, Zhong Lin Wang, and their colleagues then produced a device able to harvest both solar and wind energy and helps power these smart cities, which are predicted to harbor billions of gadgets within the IoT in just a matter of five years. The researchers integrated two energy capabilities in one for the first time: a silicon solar cell and a nanogenerator for converting wind energy into electrical output. They said that the solar cell provides 8 milliWatts (mW) of power, while the wind-harvesting part offers up to 26 mW. A single mW is estimated to light up 100 small LEDs. Under conditions simulating wind and sun, four devices situated on a model home’s roof are expected to power the LEDs inside as well as a temperature-humidity sensor. The hybrid device is said to power smart cities too when installed in huge numbers on actual rooftops. The findings were discussed in the journal ACS Nano. Recently, there are major headways made in the field of renewable energy, such as Portugal running entirely on hydro, wind and solar power for about 107 hours straight during the second week of May. Three years earlier, the country was generating a mere 7.5 percent of electricity from wind, now extending the capacity to 22 percent. Solar energy is particularly on the rise, likely going mainstream as the capacity expands tenfold within just seven years. “By the end of 2020, the amount of installed solar capacity will be 300 percent higher than today," said Dan Whitten, vice president of communications at the Solar Energy Industries Association. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | January 28, 2016
Site: phys.org

"Leaves are so abundant. All we had to do was pick one up off the ground here on campus," said Hongbian Li, a visiting professor at the University of Maryland's department of materials science and engineering and one of the main authors of the paper. Li is a member of the faculty at the National Center for Nanoscience and Technology in Beijing, China. Other studies have shown that melon skin, banana peels and peat moss can be used in this way, but a leaf needs less preparation. The scientists are trying to make a battery using sodium where most rechargeable batteries sold today use lithium. Sodium would hold more charge, but can't handle as many charge-and-discharge cycles as lithium can. One of the roadblocks has been finding an anode material that is compatible with sodium, which is slightly larger than lithium. Some scientists have explored graphene, dotted with various materials to attract and retain the sodium, but these are time consuming and expensive to produce. In this case, they simply heated the leaf for an hour at 1,000 degrees C (don't try this at home) to burn off all but the underlying carbon structure. The lower side of the maple leaf is studded with pores for the leaf to absorb water. In this new design, the pores absorb the sodium electrolyte. At the top, the layers of carbon that made the leaf tough become sheets of nanostructured carbon to absorb the sodium that carries the charge. "The natural shape of a leaf already matches a battery's needs: a low surface area, which decreases defects; a lot of small structures packed closely together, which maximizes space; and internal structures of the right size and shape to be used with sodium electrolyte," said Fei Shen, a visiting student in the department of materials science and engineering and the other main author of the paper. "We have tried other natural materials, such as wood fiber, to make a battery," said Liangbing Hu, an assistant professor of materials science and engineering. "A leaf is designed by nature to store energy for later use, and using leaves in this way could make large-scale storage environmentally friendly." The next step, Hu said, is "to investigate different types of leaves to find the best thickness, structure and flexibility" for electrical energy storage. The researchers have no plans to commercialize at this time. Explore further: An environmentally friendly battery made from wood (Update) More information: Hongbian Li et al. Carbonized-leaf Membrane with Anisotropic Surfaces for Sodium-ion Battery, ACS Applied Materials & Interfaces (2016). DOI: 10.1021/acsami.5b10875


News Article | January 29, 2016
Site: www.rdmag.com

Scientists at the University of Maryland have a new recipe for batteries: Bake a leaf, and add sodium. They used a carbonized oak leaf, pumped full of sodium, as a demonstration battery’s negative terminal, or anode, according to a paper published yesterday in the journal ACS Applied Materials Interfaces. "Leaves are so abundant. All we had to do was pick one up off the ground here on campus," said Hongbian Li, a visiting professor at the University of Maryland’s department of materials science and engineering and one of the main authors of the paper. Li is a member of the faculty at the National Center for Nanoscience and Technology in Beijing, China. Other studies have shown that melon skin, banana peels and peat moss can be used in this way, but a leaf needs less preparation. The scientists are trying to make a battery using sodium where most rechargeable batteries sold today use lithium. Sodium would hold more charge, but can’t handle as many charge-and-discharge cycles as lithium can. One of the roadblocks has been finding an anode material that is compatible with sodium, which is slightly larger than lithium. Some scientists have explored graphene, dotted with various materials to attract and retain the sodium, but these are time consuming and expensive to produce.  In this case, they simply heated the leaf for an hour at 1,000 degrees C (don’t try this at home) to burn off all but the underlying carbon structure. The lower side of the maple leaf is studded with pores for the leaf to absorb water. In this new design, the pores absorb the sodium electrolyte. At the top, the layers of carbon that made the leaf tough become sheets of nanostructured carbon to absorb the sodium that carries the charge. "The natural shape of a leaf already matches a battery’s needs: a low surface area, which decreases defects; a lot of small structures packed closely together, which maximizes space; and internal structures of the right size and shape to be used with sodium electrolyte," said Fei Shen, a visiting student in the department of materials science and engineering and the other main author of the paper. "We have tried other natural materials, such as wood fiber, to make a battery," said Liangbing Hu, an assistant professor of materials science and engineering. "A leaf is designed by nature to store energy for later use, and using leaves in this way could make large-scale storage environmentally friendly." The next step, Hu said, is "to investigate different types of leaves to find the best thickness, structure and flexibility" for electrical energy storage. The researchers have no plans to commercialize at this time. The work was supported by the Department of Energy’s Energy Frontier Research Center program, as part of Nanostructures for Electrical Energy Storage.


Ehrensperger M.,Ludwig Maximilians University of Munich | Wintterlin J.,Ludwig Maximilians University of Munich | Wintterlin J.,Center for NanoScience
Journal of Catalysis | Year: 2014

The Fischer-Tropsch synthesis of hydrocarbons from carbon monoxide and hydrogen over cobalt catalysts is expected to become the key method for the future production of liquid fuels. Despite decades of research on the reaction mechanism, the state of the surface of the operating catalyst is still uncertain. Using in situ high-temperature high-pressure scanning tunneling microscopy, we have investigated the Fischer-Tropsch reaction over a Co(0 0 0 1) single crystal model catalyst in the methanation limit. Atomically resolved images show that the surface does not transform into an oxide or carbide, but remains metallic under reaction conditions. The data are consistent with a mobile layer of reversibly adsorbed particles on the surface. The surface morphology under reaction conditions is unchanged from the surface in ultra-high vacuum. Widespread assumptions about a surface restructuring that seemed to explain the activity of cobalt-based Fischer-Tropsch catalysts are not confirmed. © 2014 Elsevier Inc. All rights reserved.


Schwinghammer K.,Max Planck Institute for Solid State Research | Schwinghammer K.,Ludwig Maximilians University of Munich | Mesch M.B.,University of Bayreuth | Duppel V.,Max Planck Institute for Solid State Research | And 7 more authors.
Journal of the American Chemical Society | Year: 2014

Nanosheets of a crystalline 2D carbon nitride were obtained by ionothermal synthesis of the layered bulk material poly(triazine imide), PTI, followed by one-step liquid exfoliation in water. Triazine-based nanosheets are 1-2 nm in height and afford chemically and colloidally stable suspensions under both basic and acidic conditions. We use solid-state NMR spectroscopy of isotopically enriched, restacked nanosheets as a tool to indirectly monitor the exfoliation process and carve out the chemical changes occurring upon exfoliation, as well as to determine the nanosheet thickness. PTI nanosheets show significantly enhanced visible-light driven photocatalytic activity toward hydrogen evolution compared to their bulk counterpart, which highlights the crucial role of morphology and surface area on the photocatalytic performance of carbon nitride materials. © 2014 American Chemical Society.


Gunther S.,Ludwig Maximilians University of Munich | Gunther S.,TU Munich | Danhardt S.,Ludwig Maximilians University of Munich | Wang B.,Ecole Normale Superieure de Lyon | And 4 more authors.
Nano Letters | Year: 2011

The epitaxial growth of graphene by chemical vapor deposition of ethylene on a Ru(0001) surface was monitored by high-temperature scanning tunneling microscopy. The in situ data show that at low pressures and high temperatures the metal surface facets into large terraces, leading to much better ordered graphene layers than resulting from the known growth mode. Density functional theory calculations show that the single terrace growth mode can be understood from the energetics of the graphene-metal interaction. © 2011 American Chemical Society.


Eichhorn J.,Ludwig Maximilians University of Munich | Heckl W.M.,Ludwig Maximilians University of Munich | Heckl W.M.,Center for NanoScience | Lackinger M.,Ludwig Maximilians University of Munich | Lackinger M.,Center for NanoScience
Chemical Communications | Year: 2013

The polymerization of 1,4-diethynylbenzene was studied on a Cu(111) surface using scanning tunneling microscopy (STM) under ultra-high vacuum conditions. Thermal activation yielded disordered covalent networks, where distinct basic structural motifs indicate different coupling reactions. This journal is © The Royal Society of Chemistry 2013.

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