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Researchers at Washington University in St. Louis hope that nanoparticle technology can help reduce the need for fertilizer, creating a more sustainable way to grow crops such as mung beans.

Scientists are working diligently to prepare for the expected increase in global population — and therefore an increased need for food production— in the coming decades. A team of engineers at Washington University in St. Louis has found a sustainable way to boost the growth of a protein-rich bean by improving the way it absorbs much-needed nutrients.Ramesh Raliya, a research scientist, and Pratim Biswas, the Lucy & Stanley Lopata Professor and chair of the Department of Energy, Environmental & Chemical Engineering, both in the School of Engineering & Applied Science, discovered a way to reduce the use of fertilizer made from rock phosphorus and still see improvements in the growth of food crops by using zinc oxide nanoparticles. Raliya said this is the first study to show how to mobilize native phosphorus in the soil using zinc oxide nanoparticles over the life cycle of the plant, from seed to harvest. Food crops need phosphorus to grow, and farmers are using more and more phosphorus-based fertilizer as they increase crops to feed a growing world population. However, the plants can only use about 42 percent of the phosphorus applied to the soil, so the rest runs off into the water streams, where it grows algae that pollutes our water sources. In addition, nearly 82 percent of the world’s phosphorus is used as fertilizer, but it is a limited supply, Raliya says. Raliya and his collaborators, including Jagadish Chandra Tarafdar at the Central Arid Zone Research Institute in Jodhpur, India, created zinc oxide nanoparticles from a fungus around the plant’s root that helps the plant mobilize and take up the nutrients in the soil. Zinc also is an essential nutrient for plants because it interacts with three enzymes that mobilize the complex form of phosphorus in the soil into a form that plants can absorb. When Raliya and the team applied the zinc nanoparticles to the leaves of the mung bean plant, it increased the uptake of the phosphorus by nearly 11 percent and the activity of the three enzymes by 84 percent to 108 percent. That leads to a lesser need to add phosphorus on the soil, Raliya said.

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Stanford and IBM researchers inserted chain-like molecules of polystyrene—the same material in a styrofoam coffee cup—between layers of nanocomposites to make these materials tougher and more flexible. (Image Credit: Dauskardt Lab, Stanford University)b, Stanford University)

Stanford and IBM researchers inserted chain-like molecules of polystyrene—the same material in a styrofoam coffee cup—between layers of nanocomposites to make these materials tougher and more flexible.(Image Credit: Dauskardt Lab, Stanford University)

By slipping springy polystyrene molecules between layers of tough yet brittle composites, researchers made materials stronger and more flexible, in the process demonstrating the theoretical limits of how far this toughening technique could go. Researchers at Stanford and IBM have tested the upper boundaries of mechanical toughness in a class of lightweight nanocomposites toughened by individual molecules, and offered a new model for how they get their toughness. The potential applications for nanocomposites cut across many industries, from computer circuitry to transportation to athletics. They could even revolutionize spaceflight with their ability to withstand tension and extreme temperatures. The study was led by Reinhold Dauskardt, a professor of materials science and engineering at Stanford University, and Geraud Dubois, of IBM's Almaden Research Center. The study was sponsored by the Air Force Office of Scientific Research.

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The recently launched EU ASCENT project recently held its 1st Users Workshop at the XXIV International Scientific Conference ‘Electronics - ET2015’ in Bulgaria. Attendees heard how ASCENT will enable access to the unique nanoelectronics infrastructure of three of Europe’s premier research centres. The Users Workshops are an important part of the ASCENT mission to support a vibrant nanoelectronics research community across Europe. The three partners (Tyndall, imec and CEA-Leti) will provide researchers with access to advanced device data, test chips, flexible fabrication and characterisation equipment. ASCENT will enable the nanoelectronics modelling-and-characterisation research community to explore exciting new developments in industry and meet the challenges created in an ever-evolving and demanding digital world. ASCENT enables Europe’s world-leading atomic scale device, TCAD and compact modelling community to perform the systematic studies that are required to develop nanoscale design methodologies and to identify the impact of quantum effects on sub-10 nm device performance. It provides an interface to global industrial leaders in nanoelectronics through the Industry Innovation Committee and through activities designed to transfer IP and technology uptake from the supported research activities. The results from the access activities will be fed back to device manufacturers to future improve the nanoscale devices being developed. ASCENT will reach out to the research community through a co-ordinated marketing campaign and will offer a simple single access route to the advanced technologies provided. ASCENT will provide technical and logistical support to Users and the results of the Access activities will be published and shared at User Workshops enabling strong interaction between the Users and Providers.

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Schematic of an infrared photodetector with graphene as its active element (Image Credit: AMO GmbH)

Infrared photodetectors in communications systems have traditionally been built as discrete devices connected to the optical fibre carrying the signal, and an electronic circuit for processing the received data. An improvement on this arrangement would be to integrate the detector and electronics on a single chip. This would substantially reduce the device footprint and fabrication cost. The maximum data rate achieved with a state-of-the-art germanium detector fabricated using the standard silicon-based CMOS production system for integrated circuits is 40 gigabits per second. However, the performance of such photodetectors is limited by the material properties, and is less than optimal, owing to silicon’s vanishing light absorption at the wavelengths used. This is driving the search for new and better materials, and graphene is considered a promising candidate.

In a paper recently published in the journal ACS Photonics, Daniel Schall and a team based at AMO in Aachen, and Alcatel-Lucent Bell Labs in Stuttgart, demonstrated photodetectors based on wafer-scale graphene. The devices are capable of recording data at up to 50 gigabits per second, and display excellent signal integrity.  Study leader Daniel Schall is a 32-year-old electrical engineer who has been with AMO since 2009, and is currently working toward a PhD at RWTH Aachen University. His work on graphene is supported by the European Commission through the Graphene Flagship.

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The illustration shows the nanofibers in white and the virus in green. (Image Source: Uppsala University; Photograph Credit: Björn Syse)

Researchers at the Division of Nanotechnology and Functional Materials, Uppsala University have developed a paper filter, which can remove virus particles with an efficiency matching that of the best industrial virus filters. The paper filter consists of 100 percent high purity cellulose nanofibers, directly derived from nature. The research was carried out in collaboration with virologists from the Swedish University of Agricultural Sciences/Swedish National Veterinary Institute. Virus particles are very peculiar objects- tiny (about thousand times thinner than a human hair) yet mighty. Viruses can only replicate in living cells but once the cells become infected the viruses can turn out to be extremely pathogenic. Viruses can actively cause diseases on their own or even transform healthy cells to malignant tumors. ‘Viral contamination of biotechnological products is a serious challenge for production of therapeutic proteins and vaccines. Because of the small size, virus removal is a non-trivial task, and, therefore, inexpensive and robust virus removal filters are highly demanded’, says Albert Mihranyan, Associate Professor at the Division of Nanotechnology and Functional Materials, Uppsala University, who heads the study.

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Gold nanoparticles make better catalysts for CO2 recycling than bulk gold metal. Size is crucial though, since edges produce more desired results than corners (red points, above). Nanoparticles of 8 nm appear to have a better edge-to-corner ratio than 4 nm, 6 nm, or 10 nm nanoparticles. Credit: Sun lab/Brown University

By tuning gold nanoparticles to just the right size, researchers from Brown University have developed a catalyst that selectively converts carbon dioxide (CO2) to carbon monoxide (CO), an active carbon molecule that can be used to make alternative fuels and commodity chemicals. “Our study shows potential of carefully designed gold nanoparticles to recycle CO2 into useful forms of carbon,” said Shouheng Sun, professor of chemistry and one of the study’s senior authors. “The work we’ve done here is preliminary, but we think there’s great potential for this technology to be scaled up for commercial applications.” The idea of recycling CO2 — a greenhouse gas the planet current has in excess — is enticing, but there are obstacles. CO2 is an extremely stable molecule that must be reduced to an active form like CO to make it useful. CO is used to make synthetic natural gas, methanol, and other alternative fuels. Converting CO2 to CO isn’t easy. Prior research has shown that catalysts made of gold foil are active for this conversion, but they don’t do the job efficiently. The gold tends to react both with the CO2 and with the water in which the CO2 is dissolved, creating hydrogen byproduct rather than the desired CO. The Brown experimental group, led by Sun and Wenlei Zhu, a graduate student in Sun’s group, wanted to see if shrinking the gold down to nanoparticles might make it more selective for CO2. They found that the nanoparticles were indeed more selective, but that the exact size of those particles was important. Eight nanometer particles had the best selectivity, achieving a 90-percent rate of conversion from CO2 to CO. Other sizes the team tested — four, six, and 10 nanometers — didn’t perform nearly as well.

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Northwestern researchers have developed a “recipe” for using nanomaterials as atoms, DNA as bonds and a little heat to form tiny crystals. An electron microscope image (left) shows a faceted single crystal consisting of nanoparticles brought together using DNA interactions. A schematic (right) illustrates how the lattice of nanoparticles is held together by DNA, taken from a simulation used to model the system. The observed crystal shape is a rhombic dodecahedron, a 12-sided polyhedron made up of congruent rhombic faces. (Image Credit: Northwestern University)

Nature builds flawless diamonds, sapphires and other gems. Now a Northwestern University research team is the first to build near-perfect single crystals out of nanoparticles and DNA, using the same structure favored by nature. “Single crystals are the backbone of many things we rely on -- diamonds for beauty as well as industrial applications, sapphires for lasers and silicon for electronics,” said nanoscientist Chad A. Mirkin. “The precise placement of atoms within a well-defined lattice defines these high-quality crystals. “Now we can do the same with nanomaterials and DNA, the blueprint of life,” Mirkin said. “Our method could lead to novel technologies and even enable new industries, much as the ability to grow silicon in perfect crystalline arrangements made possible the multibillion-dollar semiconductor industry.” His research group developed the “recipe” for using nanomaterials as atoms, DNA as bonds and a little heat to form tiny crystals. This single-crystal recipe builds on superlattice techniques Mirkin’s lab has been developing for nearly two decades. In this recent work, Mirkin, an experimentalist, teamed up with Monica Olvera de la Cruz, a theoretician, to evaluate the new technique and develop an understanding of it. Given a set of nanoparticles and a specific type of DNA, Olvera de la Cruz showed they can accurately predict the 3-D structure, or crystal shape, into which the disordered components will self-assemble.

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A carbon nanotube-coated paper triangle placed on an ionization source charged by a small battery is held in front of a mass spectrometer. Researchers at Purdue University and the Indian Institute of Technology Madras studied the use of carbon nanotubes to advance ambient ionization techniques. (Purdue University photo/Courtesy of Thalappil Pradeep)

Nanotechnology is advancing tools likened to Star Trek's "tricorder" that perform on-the-spot chemical analysis for a range of applications including medical testing, explosives detection and food safety. Researchers found that when paper used to collect a sample was coated with carbon nanotubes, the voltage required was 1,000 times reduced, the signal was sharpened and the equipment was able to capture far more delicate molecules. A team of researchers from Purdue University and the Indian Institute of Technology Madras performed the study. "This is a big step in our efforts to create miniature, handheld mass spectrometers for the field," said R. Graham Cooks, Purdue's Henry B. Hass Distinguished Professor of Chemistry. "The dramatic decrease in power required means a reduction in battery size and cost to perform the experiments. The entire system is becoming lighter and cheaper, which brings it that much closer to being viable for easy, widespread use." "Taking science to the people is what is most important," Pradeep said. "Mass spectrometry is a fantastic tool, but it is not yet on every physician's table or in the pocket of agricultural inspectors and security guards. Great techniques have been developed, but we need to hone them into tools that are affordable, can be efficiently manufactured and easily used."

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Stanford engineers have developed an improved process for making flexible circuits that use carbon nanotube transistors, a development that paves the way for a new generation of bendable electronic devices. (Bao Lab / Stanford University)

Engineers would love to create flexible electronic devices, such as e-readers that could be folded to fit into a pocket. One approach involves designing circuits based on electronic fibers, known as carbon nanotubes (CNTs), instead of rigid silicon chips. But reliability is essential. Most silicon chips are based on a type of circuit design that allows them to function flawlessly even when the device experiences power fluctuations. However, it is much more challenging to do so with CNT circuits. But now a team at Stanford University has developed a process to create flexible chips that can tolerate power fluctuations in much the same way as silicon circuitry. This is the first time anyone has designed flexible CNT circuits that have both high immunity to electrical noise and low power consumption," said Zhenan Bao, a professor of chemical engineering at Stanford.  In principle, CNTs should be ideal for making flexible electronic circuitry. These ultra-thin carbon filaments have the physical strength to take the wear and tear of bending and the electrical conductivity to perform any electronic task. But until this recent work from the Stanford team, flexible CNT circuits didn't have the reliability and power-efficiency of rigid silicon chips. The Stanford process also has some potential application to rigid CNTs. Although other engineers have previously doped rigid CNTs to create this immunity to electrical noise, the precise and finely tuned Stanford process out-performs these prior efforts, suggesting that it could be useful for both flexible and rigid CNT circuitry. Bao has focused her research on flexible CNTs, which compete with other experimental materials, such as specially formulated plastics, to become the foundation for bendable electronics, just as silicon has been the basis for rigid electronics.

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Image, courtesy of Dr. Matthew Lefebre and Professor Jorge Galan (Yale University), shows parts of nanoinjectors from Salmonella as seen under an electron microscope. Image Source: University of Kansas Press.

If you’ve ever suffered the misery of food poisoning from a bacterium like Shigella or Salmonella, then your cells have been on the receiving end of “nanoinjectors” — microscopic spikes made from proteins through which pathogens secrete effector proteins into human host cells, causing infection. Many bacteria use nanoinjectors to infect millions of people around the world every year. Today, Roberto De Guzman, associate professor of molecular biosciences at the University of Kansas, is leading a research group that is evaluating the potential of nanoinjectors as a target for a new class of antibiotics. Their work is funded by a five-year, $1.8 million grant from the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health. “This grant will support our studies on elucidating how bacterial nanoinjectors are assembled,” said De Guzman. “Nanoinjectors are protein machinery used by bacterial pathogens to inject virulence proteins into human cells to cause infectious diseases. They are nanoscale is size — they look like needles and bacteria use them to inject virulence proteins into host cells — so I called them nanoinjectors. In microbiology, they are known as part of the type III secretion system, a protein delivery machinery.” The KU researcher said nanoinjectors are unique to pathogenic bacteria and are absolutely required for infectivity. Most people have heard of the diseases caused by bacterial pathogens that employ nanoinjectors — several of which have changed the course of the human experience for the worse.

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