Tag Archives: US

Nanophotonics transforms Raman spectroscopy at Rice University (US)

This new technique for sensing molecules is intriguing. From a July 15, 2014 news item on Azonano,

Nanophotonics experts at Rice University [Texas, US] have created a unique sensor that amplifies the optical signature of molecules by about 100 billion times. Newly published tests found the device could accurately identify the composition and structure of individual molecules containing fewer than 20 atoms.

The new imaging method, which is described this week in the journal Nature Communications, uses a form of Raman spectroscopy in combination with an intricate but mass reproducible optical amplifier. Researchers at Rice’s Laboratory for Nanophotonics (LANP) said the single-molecule sensor is about 10 times more powerful that previously reported devices.

A July 15, 2014 Rice University news release (also on EurekAlert), which originated the news item, provides more detail about the research,

“Ours and other research groups have been designing single-molecule sensors for several years, but this new approach offers advantages over any previously reported method,” said LANP Director Naomi Halas, the lead scientist on the study. “The ideal single-molecule sensor would be able to identify an unknown molecule — even a very small one — without any prior information about that molecule’s structure or composition. That’s not possible with current technology, but this new technique has that potential.”

The optical sensor uses Raman spectroscopy, a technique pioneered in the 1930s that blossomed after the advent of lasers in the 1960s. When light strikes a molecule, most of its photons bounce off or pass directly through, but a tiny fraction — fewer than one in a trillion — are absorbed and re-emitted into another energy level that differs from their initial level. By measuring and analyzing these re-emitted photons through Raman spectroscopy, scientists can decipher the types of atoms in a molecule as well as their structural arrangement.

Scientists have created a number of techniques to boost Raman signals. In the new study, LANP graduate student Yu Zhang used one of these, a two-coherent-laser technique called “coherent anti-Stokes Raman spectroscopy,” or CARS. By using CARS in conjunction with a light amplifier made of four tiny gold nanodiscs, Halas and Zhang were able to measure single molecules in a powerful new way. LANP has dubbed the new technique “surface-enhanced CARS,” or SECARS.

“The two-coherent-laser setup in SECARS is important because the second laser provides further amplification,” Zhang said. “In a conventional single-laser setup, photons go through two steps of absorption and re-emission, and the optical signatures are usually amplified around 100 million to 10 billion times. By adding a second laser that is coherent with the first one, the SECARS technique employs a more complex multiphoton process.”

Zhang said the additional amplification gives SECARS the potential to address most unknown samples. That’s an added advantage over current techniques for single-molecule sensing, which generally require a prior knowledge about a molecule’s resonant frequency before it can be accurately measured.

Another key component of the SECARS process is the device’s optical amplifier, which contains four tiny gold discs in a precise diamond-shaped arrangement. The gap in the center of the four discs is about 15 nanometers wide. Owing to an optical effect called a “Fano resonance,” the optical signatures of molecules caught in that gap are dramatically amplified because of the efficient light harvesting and signal scattering properties of the four-disc structure.

Fano resonance requires a special geometric arrangement of the discs, and one of LANP’s specialties is the design, production and analysis of Fano-resonant plasmonic structures like the four-disc “quadrumer.” In previous LANP research, other geometric disc structures were used to create powerful optical processors.

Zhang said the quadrumer amplifiers are a key to SECARS, in part because they are created with standard e-beam lithographic techniques, which means they can be easily mass-produced.

“A 15-nanometer gap may sound small, but the gap in most competing devices is on the order of 1 nanometer,” Zhang said. “Our design is much more robust because even the smallest defect in a one-nanometer device can have significant effects. Moreover, the larger gap also results in a larger target area, the area where measurements take place. The target area in our device is hundreds of times larger than the target area in a one-nanometer device, and we can measure molecules anywhere in that target area, not just in the exact center.”

Halas, the Stanley C. Moore Professor in Electrical and Computer Engineering and a professor of biomedical engineering, chemistry, physics and astronomy at Rice, said the potential applications for SECARS include chemical and biological sensing as well as metamaterials research. She said scientific labs are likely be the first beneficiaries of the technology.

“Amplification is important for sensing small molecules because the smaller the molecule, the weaker the optical signature,” Halas said. “This amplification method is the most powerful yet demonstrated, and it could prove useful in experiments where existing techniques can’t provide reliable data.”

Here’s a link to and a citation for the paper,

Coherent anti-Stokes Raman scattering with single-molecule sensitivity using a plasmonic Fano resonance by Yu Zhang, Yu-Rong Zhen, Oara Neumann, Jared K. Day, Peter Nordlander & Naomi J. Halas. Nature Communications 5, Article number: 4424 doi:10.1038/ncomms5424 Published 14 July 2014

This paper is behind a paywall.

Squishy but rigid robots from MIT (Massachusetts Institute of Technology)

A July 14, 2014 news item on ScienceDaily MIT (Massachusetts Institute of Technology) features robots that mimic mice and other biological constructs or, if you prefer, movie robots,

In the movie “Terminator 2,” the shape-shifting T-1000 robot morphs into a liquid state to squeeze through tight spaces or to repair itself when harmed.

Now a phase-changing material built from wax and foam, and capable of switching between hard and soft states, could allow even low-cost robots to perform the same feat.

The material — developed by Anette Hosoi, a professor of mechanical engineering and applied mathematics at MIT, and her former graduate student Nadia Cheng, alongside researchers at the Max Planck Institute for Dynamics and Self-Organization and Stony Brook University — could be used to build deformable surgical robots. The robots could move through the body to reach a particular point without damaging any of the organs or vessels along the way.

A July 14, 2014 MIT news release (also on EurekAlert), which originated the news item, describes the research further by referencing both octopuses and jello,

Working with robotics company Boston Dynamics, based in Waltham, Mass., the researchers began developing the material as part of the Chemical Robots program of the Defense Advanced Research Projects Agency (DARPA). The agency was interested in “squishy” robots capable of squeezing through tight spaces and then expanding again to move around a given area, Hosoi says — much as octopuses do.

But if a robot is going to perform meaningful tasks, it needs to be able to exert a reasonable amount of force on its surroundings, she says. “You can’t just create a bowl of Jell-O, because if the Jell-O has to manipulate an object, it would simply deform without applying significant pressure to the thing it was trying to move.”

What’s more, controlling a very soft structure is extremely difficult: It is much harder to predict how the material will move, and what shapes it will form, than it is with a rigid robot.

So the researchers decided that the only way to build a deformable robot would be to develop a material that can switch between a soft and hard state, Hosoi says. “If you’re trying to squeeze under a door, for example, you should opt for a soft state, but if you want to pick up a hammer or open a window, you need at least part of the machine to be rigid,” she says.

Compressible and self-healing

To build a material capable of shifting between squishy and rigid states, the researchers coated a foam structure in wax. They chose foam because it can be squeezed into a small fraction of its normal size, but once released will bounce back to its original shape.

The wax coating, meanwhile, can change from a hard outer shell to a soft, pliable surface with moderate heating. This could be done by running a wire along each of the coated foam struts and then applying a current to heat up and melt the surrounding wax. Turning off the current again would allow the material to cool down and return to its rigid state.

In addition to switching the material to its soft state, heating the wax in this way would also repair any damage sustained, Hosoi says. “This material is self-healing,” she says. “So if you push it too far and fracture the coating, you can heat it and then cool it, and the structure returns to its original configuration.”

To build the material, the researchers simply placed the polyurethane foam in a bath of melted wax. They then squeezed the foam to encourage it to soak up the wax, Cheng says. “A lot of materials innovation can be very expensive, but in this case you could just buy really low-cost polyurethane foam and some wax from a craft store,” she says.

In order to study the properties of the material in more detail, they then used a 3-D printer to build a second version of the foam lattice structure, to allow them to carefully control the position of each of the struts and pores.

When they tested the two materials, they found that the printed lattice was more amenable to analysis than the polyurethane foam, although the latter would still be fine for low-cost applications, Hosoi says.

The wax coating could also be replaced by a stronger material, such as solder, she adds.

Hosoi is now investigating the use of other unconventional materials for robotics, such as magnetorheological and electrorheological fluids. These materials consist of a liquid with particles suspended inside, and can be made to switch from a soft to a rigid state with the application of a magnetic or electric field.

When it comes to artificial muscles for soft and biologically inspired robots, we tend to think of controlling shape through bending or contraction, says Carmel Majidi, an assistant professor of mechanical engineering in the Robotics Institute at Carnegie Mellon University, who was not involved in the research. “But for a lot of robotics tasks, reversibly tuning the mechanical rigidity of a joint can be just as important,” he says. “This work is a great demonstration of how thermally controlled rigidity-tuning could potentially be used in soft robotics.”

Here’s a link to and a citation for the paper,

Thermally Tunable, Self-Healing Composites for Soft Robotic Applications by Nadia G. Cheng, Arvind Gopinath, Lifeng Wang, Karl Iagnemma, and Anette E. Hosoi. Macromolecular Materials and Engineering DOI: 10.1002/mame.201400017 Article first published online: 30 JUN 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Deadline extension (travel grants and poster abstracts) for alternate testing strategies (ATS) of nanomaterials workshop

It seems there have been a couple of deadline extensions (to August 1, 2014) for the September 15-16, 2014 ‘Workshop to Explore How a Multiple Models Approach can Advance Risk Analysis of Nanoscale Materials’ in Washington, DC (first mentioned in my July 10, 2014 posting featuring a description of the workshop). You can go here to submit a poster abstract (from any country) and you can go here if you’re a student or young professional (from any country) in search of a $500 travel award.

I managed to speak to one of the organizers, Lorraine Sheremeta, (Assistant Director, Ingenuity Lab, University of Alberta and co-author a July 9, 2014 Nanowerk Spotlight article about the workshop). Lorraine (Lori) kindly spoke to me about the upcoming workshop, which she described as an academic conference,.

As I understand what she told me, the hosts for the September 15-16, 2014 Workshop to Explore How a Multiple Models Approach can Advance Risk Analysis of Nanoscale Materials in Washington, DC want to attract a multidisciplinary group of people to grapple with a few questions. First, they want to establish a framework for establishing which are the best test methods for nanomaterials. Second, they are trying to move away from animal testing and want to establish which methods are equal to or better than animal testing. Thirdly, they want to discuss what they are going to do with the toxicological data  that we have  been collecting on nanomaterials for years now.

Or, as she and her colleague from the Society of Risk Analysis (Jo Anne Shatkin) have put in it in their Nanowerk Spotlight article:

… develop a report on the State of the Science for ATS for nanomaterials, catalogue of existing and emerging ATS [alternate testing strategies] methods in a database; and develop a case study to inform workshop deliberations and expert recommendations

The collaborative team behind this event includes, the University of Alberta’s Ingenuity Lab, the Society for Risk Analysis, Environment Canada, Health Canada, and the Organization for Economic Co-operation and Development (OECD) Working Party on Manufactured Nanomaterials (WPMN) .

The speaker lineup isn’t settled at this time although they have confirmed Vicki Stone of Heriot-Watt University in Scotland (from her university bio page),

Vicki Stone, Professor of Toxicology, studies the effects of nanomaterials on humans and environmentally relevant species.  Current research projects investigate the mechanism of toxicity of a range of nanomaterials in cells of the immune system (macrophages and neutrophils), liver (hepatocytes) , gastrointestinal tract, blood vessels (endothelium) and lung.  She is interested in interactions between nanomaterials, proteins and lipids, and how this influences subsequent toxicity.  Current projects also develop in vitro alternatives using microfluidics as well as high resolution imaging of individual nanomaterials in 3D and over time.  In addition Vicki collaborates with ecotoxicologists to investigate the impacts of nanomaterials on aquatic organisms. Vicki coordinated a European project to identify the research priorities to develop an intelligent testing strategy for nanomaterials (www.its-nano.eu).

Vicki is Director of the Nano Safety Research Group at Heriot-Watt University, Edinburgh, and Director of Toxicology for SAFENANO (www.safenano.org). She has acted as the Editor-in-chief of the journal Nanotoxicology (http://informahealthcare.com/nan) for 6 years (2006-2011). Vicki has also published over 130 publications pertaining to particle toxicology over the last 16 years and has provided evidence for the government commissioned reports published by the Royal Society (2003) and the on Environmental Pollution (2008).  Vicki was previously a member of the UK Government Committee on the Medical Effects of Air Pollution (COMEAP) and an advisory board member for the Center for the Environmental Implications of NanoTechnology (CEINT; funded by the US Environmental Protection Agency)).

A representative from PETA (People for the Ethical Treatment of Animals) will also be speaking. I believe that will be Amy Clippinger (from the PETA website’s Regulatory Testing webpage; scroll down about 70% of the way),

Science adviser Amy Clippinger has a Ph.D. in cellular and molecular biology and genetics and several years of research experience at the University of Pennsylvania.

PETA representatives have been to at least one other conference on the topic of nano, toxicology, and animal testing as per my April 24, 2014 posting about NANOTOX 2014 in Turkey,

Writing about nanotechnology can lead you in many different directions such as the news about PETA (People for the Ethical Treatment of Animals) and its poster presentation at the NanoTox 2014 conference being held in Antalya, Turkey from April 23 – 26, 2014. From the April 22, 2014 PETA news release on EurekAlert,

PETA International Science Consortium Ltd.’s nanotechnology expert will present a poster titled “A tiered-testing strategy for nanomaterial hazard assessment” at the 7th International Nanotoxicology Congress [NanoTox 2014] to be held April 23-26, 2014, in Antalya, Turkey.

Dr. Monita Sharma will outline a strategy consistent with the 2007 report from the US National Academy of Sciences, “Toxicity Testing in the 21st Century: A Vision and a Strategy,” which recommends use of non-animal methods involving human cells and cell lines for mechanistic pathway–based toxicity studies.

There is a lot of interest internationally in improving how we test for toxicity of nanomaterials. As well, the drive to eliminate or minimize as much as possible the use of animals in testing seems to be gaining momentum.

Good luck to everyone submitting a poster abstract and/or an application for a travel grant!

In case you don’t want to scroll up, the SRA nano workshop website is here.

Boron as a ‘buckyball’ or borospherene

First there was the borophene (like graphene but using boron rather than carbon) announcement from Brown University in my Jan. 28, 214 posting and now US (Brown University again) and Chinese researchers have developed a boron ‘buckyball’. Coincidentally, this announcement comes just after the 2014 World Cup final (July 13, 2014). Representations of buckyballs always resemble soccer balls. (Note: Germany won.)

From a July 14, 2014 news item on Azonano,

The discovery 30 years ago of soccer-ball-shaped carbon molecules called buckyballs helped to spur an explosion of nanotechnology research. Now, there appears to be a new ball on the pitch.

Researchers from Brown University, Shanxi University and Tsinghua University in China have shown that a cluster of 40 boron atoms forms a hollow molecular cage similar to a carbon buckyball. It’s the first experimental evidence that a boron cage structure—previously only a matter of speculation—does indeed exist.

“This is the first time that a boron cage has been observed experimentally,” said Lai-Sheng Wang, a professor of chemistry at Brown who led the team that made the discovery. “As a chemist, finding new molecules and structures is always exciting. The fact that boron has the capacity to form this kind of structure is very interesting.”

The researchers have provided an illustration of their borospherene,

The carbon buckyball has a boron cousin. A cluster for 40 boron atoms forms a hollow cage-like molecule. Courtesy Brown University

The carbon buckyball has a boron cousin. A cluster for 40 boron atoms forms a hollow cage-like molecule. Courtesy Brown University

A July 9, 2104 Brown University news release (also on EurekAlert), which originated the news item, describes the borosphene’s predecessor, the carbon buckyball, and provides more details about this new molecule,

Carbon buckyballs are made of 60 carbon atoms arranged in pentagons and hexagons to form a sphere — like a soccer ball. Their discovery in 1985 was soon followed by discoveries of other hollow carbon structures including carbon nanotubes. Another famous carbon nanomaterial — a one-atom-thick sheet called graphene — followed shortly after.

After buckyballs, scientists wondered if other elements might form these odd hollow structures. One candidate was boron, carbon’s neighbor on the periodic table. But because boron has one less electron than carbon, it can’t form the same 60-atom structure found in the buckyball. The missing electrons would cause the cluster to collapse on itself. If a boron cage existed, it would have to have a different number of atoms.

Wang and his research group have been studying boron chemistry for years. In a paper published earlier this year, Wang and his colleagues showed that clusters of 36 boron atoms form one-atom-thick disks, which might be stitched together to form an analog to graphene, dubbed borophene. Wang’s preliminary work suggested that there was also something special about boron clusters with 40 atoms. They seemed to be abnormally stable compared to other boron clusters.

Figuring out what that 40-atom cluster actually looks like required a combination of experimental work and modeling using high-powered supercomputers.

On the computer, Wang’s colleagues modeled over 10,000 possible arrangements of 40 boron atoms bonded to each other. The computer simulations estimate not only the shapes of the structures, but also estimate the electron binding energy for each structure — a measure of how tightly a molecule holds its electrons. The spectrum of binding energies serves as a unique fingerprint of each potential structure.

The next step is to test the actual binding energies of boron clusters in the lab to see if they match any of the theoretical structures generated by the computer. To do that, Wang and his colleagues used a technique called photoelectron spectroscopy.

Chunks of bulk boron are zapped with a laser to create vapor of boron atoms. A jet of helium then freezes the vapor into tiny clusters of atoms. The clusters of 40 atoms were isolated by weight then zapped with a second laser, which knocks an electron out of the cluster. The ejected electron flies down a long tube Wang calls his “electron racetrack.” The speed at which the electrons fly down the racetrack is used to determine the cluster’s electron binding energy spectrum — its structural fingerprint.

The experiments showed that 40-atom-clusters form two structures with distinct binding spectra. Those spectra turned out to be a dead-on match with the spectra for two structures generated by the computer models. One was a semi-flat molecule and the other was the buckyball-like spherical cage.

“The experimental sighting of a binding spectrum that matched our models was of paramount importance,” Wang said. “The experiment gives us these very specific signatures, and those signatures fit our models.”

The borospherene molecule isn’t quite as spherical as its carbon cousin. Rather than a series of five- and six-membered rings formed by carbon, borospherene consists of 48 triangles, four seven-sided rings and two six-membered rings. Several atoms stick out a bit from the others, making the surface of borospherene somewhat less smooth than a buckyball.

As for possible uses for borospherene, it’s a little too early to tell, Wang says. One possibility, he points out, could be hydrogen storage. Because of the electron deficiency of boron, borospherene would likely bond well with hydrogen. So tiny boron cages could serve as safe houses for hydrogen molecules.

But for now, Wang is enjoying the discovery.

“For us, just to be the first to have observed this, that’s a pretty big deal,” Wang said. “Of course if it turns out to be useful that would be great, but we don’t know yet. Hopefully this initial finding will stimulate further interest in boron clusters and new ideas to synthesize them in bulk quantities.”

The theoretical modeling was done with a group led by Prof. Si-Dian Li from Shanxi University and a group led by Prof. Jun Li from Tsinghua University. The work was supported by the U.S. National Science Foundation (CHE-1263745) and the National Natural Science Foundation of China.

Here’s a link to and a citation for the paper,

Observation of an all-boron fullerene by Hua-Jin Zhai, Ya-Fan Zhao, Wei-Li Li, Qiang Chen, Hui Bai, Han-Shi Hu, Zachary A. Piazza, Wen-Juan Tian, Hai-Gang Lu, Yan-Bo Wu, Yue-Wen Mu, Guang-Feng Wei, Zhi-Pan Liu, Jun Li, Si-Dian Li, & Lai-Sheng Wang. Nature Chemistry (2014) doi:10.1038/nchem.1999 Published online 13 July 2014

This paper is behind a paywall.

Better RRAM memory devices in the short term

Given my recent spate of posts about computing and the future of the chip (list to follow at the end of this post), this Rice University [Texas, US] research suggests that some improvements to current memory devices might be coming to the market in the near future. From a July 12, 2014 news item on Azonano,

Rice University’s breakthrough silicon oxide technology for high-density, next-generation computer memory is one step closer to mass production, thanks to a refinement that will allow manufacturers to fabricate devices at room temperature with conventional production methods.

A July 10, 2014 Rice University news release, which originated the news item, provides more detail,

Tour and colleagues began work on their breakthrough RRAM technology more than five years ago. The basic concept behind resistive memory devices is the insertion of a dielectric material — one that won’t normally conduct electricity — between two wires. When a sufficiently high voltage is applied across the wires, a narrow conduction path can be formed through the dielectric material.

The presence or absence of these conduction pathways can be used to represent the binary 1s and 0s of digital data. Research with a number of dielectric materials over the past decade has shown that such conduction pathways can be formed, broken and reformed thousands of times, which means RRAM can be used as the basis of rewritable random-access memory.

RRAM is under development worldwide and expected to supplant flash memory technology in the marketplace within a few years because it is faster than flash and can pack far more information into less space. For example, manufacturers have announced plans for RRAM prototype chips that will be capable of storing about one terabyte of data on a device the size of a postage stamp — more than 50 times the data density of current flash memory technology.

The key ingredient of Rice’s RRAM is its dielectric component, silicon oxide. Silicon is the most abundant element on Earth and the basic ingredient in conventional microchips. Microelectronics fabrication technologies based on silicon are widespread and easily understood, but until the 2010 discovery of conductive filament pathways in silicon oxide in Tour’s lab, the material wasn’t considered an option for RRAM.

Since then, Tour’s team has raced to further develop its RRAM and even used it for exotic new devices like transparent flexible memory chips. At the same time, the researchers also conducted countless tests to compare the performance of silicon oxide memories with competing dielectric RRAM technologies.

“Our technology is the only one that satisfies every market requirement, both from a production and a performance standpoint, for nonvolatile memory,” Tour said. “It can be manufactured at room temperature, has an extremely low forming voltage, high on-off ratio, low power consumption, nine-bit capacity per cell, exceptional switching speeds and excellent cycling endurance.”

In the latest study, a team headed by lead author and Rice postdoctoral researcher Gunuk Wang showed that using a porous version of silicon oxide could dramatically improve Rice’s RRAM in several ways. First, the porous material reduced the forming voltage — the power needed to form conduction pathways — to less than two volts, a 13-fold improvement over the team’s previous best and a number that stacks up against competing RRAM technologies. In addition, the porous silicon oxide also allowed Tour’s team to eliminate the need for a “device edge structure.”

“That means we can take a sheet of porous silicon oxide and just drop down electrodes without having to fabricate edges,” Tour said. “When we made our initial announcement about silicon oxide in 2010, one of the first questions I got from industry was whether we could do this without fabricating edges. At the time we could not, but the change to porous silicon oxide finally allows us to do that.”

Wang said, “We also demonstrated that the porous silicon oxide material increased the endurance cycles more than 100 times as compared with previous nonporous silicon oxide memories. Finally, the porous silicon oxide material has a capacity of up to nine bits per cell that is highest number among oxide-based memories, and the multiple capacity is unaffected by high temperatures.”

Tour said the latest developments with porous silicon oxide — reduced forming voltage, elimination of need for edge fabrication, excellent endurance cycling and multi-bit capacity — are extremely appealing to memory companies.

“This is a major accomplishment, and we’ve already been approached by companies interested in licensing this new technology,” he said.

Here’s a link to and a citation for the paper,

Nanoporous Silicon Oxide Memory by Gunuk Wang, Yang Yang, Jae-Hwang Lee, Vera Abramova, Huilong Fei, Gedeng Ruan, Edwin L. Thomas, and James M. Tour. Nano Lett., Article ASAP DOI: 10.1021/nl501803s Publication Date (Web): July 3, 2014

Copyright © 2014 American Chemical Society

This paper is behind a paywall.

As for my recent spate of posts on computers and chips, there’s a July 11, 2014 posting about IBM, a 7nm chip, and much more; a July 9, 2014 posting about Intel and its 14nm low-power chip processing and plans for a 10nm chip; and, finally, a June 26, 2014 posting about HP Labs and its plans for memristive-based computing and their project dubbed ‘The Machine’.

Sand and nanotechnology

There’s some good news coming out of the University of California, Riverside regarding sand and lithium-ion (li-ion) batteries, which I will temper with some additional information later in this posting.

First, the good news is that researchers have a new non-toxic, low cost way to produce a component in lithium-ion (li-ion) batteries according to a July 8, 2014 news item on ScienceDaily,

Researchers at the University of California, Riverside’s Bourns College of Engineering have created a lithium ion battery that outperforms the current industry standard by three times. The key material: sand. Yes, sand.

“This is the holy grail — a low cost, non-toxic, environmentally friendly way to produce high performance lithium ion battery anodes,” said Zachary Favors, a graduate student working with Cengiz and Mihri Ozkan, both engineering professors at UC Riverside.

The idea came to Favors six months ago. He was relaxing on the beach after surfing in San Clemente, Calif. when he picked up some sand, took a close look at it and saw it was made up primarily of quartz, or silicon dioxide.

His research is centered on building better lithium ion batteries, primarily for personal electronics and electric vehicles. He is focused on the anode, or negative side of the battery. Graphite is the current standard material for the anode, but as electronics have become more powerful graphite’s ability to be improved has been virtually tapped out.

A July 8, 2014 University of California at Riverside news release by Sean Nealon, which originated the news item, describes some of the problems with silicon as a replacement for graphite and how the researchers approached those problems,

Researchers are now focused on using silicon at the nanoscale, or billionths of a meter, level as a replacement for graphite. The problem with nanoscale silicon is that it degrades quickly and is hard to produce in large quantities.

Favors set out to solve both these problems. He researched sand to find a spot in the United States where it is found with a high percentage of quartz. That took him to the Cedar Creek Reservoir, east of Dallas, where he grew up.

Sand in hand, he came back to the lab at UC Riverside and milled it down to the nanometer scale, followed by a series of purification steps changing its color from brown to bright white, similar in color and texture to powdered sugar.

After that, he ground salt and magnesium, both very common elements found dissolved in sea water into the purified quartz. The resulting powder was then heated. With the salt acting as a heat absorber, the magnesium worked to remove the oxygen from the quartz, resulting in pure silicon.

The Ozkan team was pleased with how the process went. And they also encountered an added positive surprise. The pure nano-silicon formed in a very porous 3-D silicon sponge like consistency. That porosity has proved to be the key to improving the performance of the batteries built with the nano-silicon.

Now, the Ozkan team is trying to produce larger quantities of the nano-silicon beach sand and is planning to move from coin-size batteries to pouch-size batteries that are used in cell phones.

The research is supported by Temiz Energy Technologies. The UCR Office of Technology Commercialization has filed patents for inventions reported in the research paper.

Here’s a link to and a citation for the research paper,

Scalable Synthesis of Nano-Silicon from Beach Sand for Long Cycle Life Li-ion Batteries by Zachary Favors, Wei Wang, Hamed Hosseini Bay, Zafer Mutlu, Kazi Ahmed, Chueh Liu, Mihrimah Ozkan, & Cengiz S. Ozkan. Scientific Reports 4, Article number: 5623 doi:10.1038/srep05623 Published 08 July 2014

While this is good news, it does pose a conundrum of sorts. It seems that supplies of sand are currently under siege. A documentary, Sand Wars (2013) lays out the issues (from the Sand Wars website’s Synopsis page),

Most of us think of it as a complimentary ingredient of any beach vacation. Yet those seemingly insignificant grains of silica surround our daily lives. Every house, skyscraper and glass building, every bridge, airport and sidewalk in our modern society depends on sand. We use it to manufacture optical fiber, cell phone components and computer chips. We find it in our toothpaste, powdered foods and even in our glass of wine (both the glass and the wine, as a fining agent)!

Is sand an infinite resource? Can the existing supply satisfy a gigantic demand fueled by construction booms?  What are the consequences of intensive beach sand mining for the environment and the neighboring populations?

Based on encounters with sand smugglers, barefoot millionaires, corrupt politicians, unscrupulous real estate developers and environmentalists, this investigation takes us around the globe to unveil a new gold rush and a disturbing fact: the “SAND WARS” have begun.

Dr. Muditha D Senarath Yapa of John Keells Research at John Keells Holdings comments on the situation in Sri Lanka in his June 22, 2014 article (Nanotechnology – Depleting the most precious minerals for a few dollars) for The Nation,

Many have written for many years about the mineral sands of Pulmoddai. It is a national tragedy that for more than 50 years, we have been depleting the most precious minerals of our land for a few dollars. There are articles that appeared in various newspapers on how the mineral sands industry has boomed over the years. I hope the readers understand that it only means that we are depleting our resources faster than ever. According to the Lanka Mineral Sands Limited website, 90,000 tonnes of ilmenite, 9,000 tonnes of rutile, 5,500 tonnes of zircon, 100 tonnes of monazite and 4,000 tonnes of high titanium ilmenite are produced annually and shipped away to other countries.

… It is time for Sri Lanka to look at our own resources with this new light and capture the future nano materials market to create value added materials.

It’s interesting that he starts with the depletion of the sands as a national tragedy and ends with a plea to shift from a resource-based economy to a manufacturing-based economy. (This plea resonates strongly here in Canada where we too are a resource-based economy.)

Sidebar: John Keells Holdings is a most unusual company, from the About Us page,

In terms of market capitalisation, John Keells Holdings PLC is one of the largest listed conglomerate on the Colombo Stock Exchange. Other measures tell a similar tale; our group companies manage the largest number of hotel rooms in Sri Lanka, own the country’s largest privately-owned transportation business and hold leading positions in Sri Lanka’s key industries: tea, food and beverage manufacture and distribution, logistics, real estate, banking and information technology. Our investment in Sri Lanka is so deep and widely diversified that our stock price is sometimes used by international financial analysts as a benchmark of the country’s economy.

Yapa heads the companies research effort, which recently celebrated a synthetic biology agreement (from a May 2014 John Keells news release by Nuwan),

John Keells Research Signs an Historic Agreement with the Human Genetics Unit, Faculty of Medicine, University of Colombo to establish Sri Lanka’s first Synthetic Biology Research Programme.

Getting back to sand, these three pieces, ‘sand is good for li-ion batteries’, ‘sand is a diminishing resource’, and ‘let’s stop being a source of sand for other countries’ lay bare some difficult questions about our collective future on this planet.

Nanojuice in your gut

A July 7, 2014 news item on Azonano features a new technique that could help doctors better diagnose problems in the intestines (guts),

Located deep in the human gut, the small intestine is not easy to examine. X-rays, MRIs and ultrasound images provide snapshots but each suffers limitations. Help is on the way.

University at Buffalo [State University of New York] researchers are developing a new imaging technique involving nanoparticles suspended in liquid to form “nanojuice” that patients would drink. Upon reaching the small intestine, doctors would strike the nanoparticles with a harmless laser light, providing an unparalleled, non-invasive, real-time view of the organ.

A July 5, 2014 University of Buffalo news release (also on EurekAlert) by Cory Nealon, which originated the news item, describes some of the challenges associated with medical imaging of small intestines,

“Conventional imaging methods show the organ and blockages, but this method allows you to see how the small intestine operates in real time,” said corresponding author Jonathan Lovell, PhD, UB assistant professor of biomedical engineering. “Better imaging will improve our understanding of these diseases and allow doctors to more effectively care for people suffering from them.”

The average human small intestine is roughly 23 feet long and 1 inch thick. Sandwiched between the stomach and large intestine, it is where much of the digestion and absorption of food takes place. It is also where symptoms of irritable bowel syndrome, celiac disease, Crohn’s disease and other gastrointestinal illnesses occur.

To assess the organ, doctors typically require patients to drink a thick, chalky liquid called barium. Doctors then use X-rays, magnetic resonance imaging and ultrasounds to assess the organ, but these techniques are limited with respect to safety, accessibility and lack of adequate contrast, respectively.

Also, none are highly effective at providing real-time imaging of movement such as peristalsis, which is the contraction of muscles that propels food through the small intestine. Dysfunction of these movements may be linked to the previously mentioned illnesses, as well as side effects of thyroid disorders, diabetes and Parkinson’s disease.

The news release goes on to describe how the researchers manipulated dyes that are usually unsuitable for the purpose of imaging an organ in the body,

Lovell and a team of researchers worked with a family of dyes called naphthalcyanines. These small molecules absorb large portions of light in the near-infrared spectrum, which is the ideal range for biological contrast agents.

They are unsuitable for the human body, however, because they don’t disperse in liquid and they can be absorbed from the intestine into the blood stream.

To address these problems, the researchers formed nanoparticles called “nanonaps” that contain the colorful dye molecules and added the abilities to disperse in liquid and move safely through the intestine.

In laboratory experiments performed with mice, the researchers administered the nanojuice orally. They then used photoacoustic tomography (PAT), which is pulsed laser lights that generate pressure waves that, when measured, provide a real-time and more nuanced view of the small intestine.

The researchers plan to continue to refine the technique for human trials, and move into other areas of the gastrointestinal tract.

Here’s an image of the nanojuice in the guts of a mouse,

The combination of "nanojuice" and photoacoustic tomography illuminates the intestine of a mouse. (Credit: Jonathan Lovell)

The combination of “nanojuice” and photoacoustic tomography illuminates the intestine of a mouse. (Credit: Jonathan Lovell)

This is an international collaboration both from a research perspective and a funding perspective (from the news release),

Additional authors of the study come from UB’s Department of Chemical and Biological Engineering, Pohang University of Science and Technology in Korea, Roswell Park Cancer Institute in Buffalo, the University of Wisconsin-Madison, and McMaster University in Canada.

The research was supported by grants from the National Institutes of Health, the Department of Defense and the Korean Ministry of Science, ICT and Future Planning.

Here’s a link to and a citation for the paper,

Non-invasive multimodal functional imaging of the intestine with frozen micellar naphthalocyanines by Yumiao Zhang, Mansik Jeon, Laurie J. Rich, Hao Hong, Jumin Geng, Yin Zhang, Sixiang Shi, Todd E. Barnhart, Paschalis Alexandridis, Jan D. Huizinga, Mukund Seshadri, Weibo Cai, Chulhong Kim, & Jonathan F. Lovell. Nature Nanotechnology (2014) doi:10.1038/nnano.2014.130 Published online 06 July 2014

This paper is behind a paywall.

Bringing the Nanoworld Together Workshop in Beijing, China, Sept. 24 – 25, 2014

The speakers currently confirmed for the ‘Bringing the Nanoworld Together Workshop organized by Oxford Instruments are from the UK, China, Canada, the US, and the Netherlands as per a July 2, 2014 news item on Nanowerk (Note: A link has been removed),

‘Bringing the Nanoworld Together’ is an event organised by Oxford Instruments to share the expertise of scientists in the field of Nanotechnology. It will be hosted at the IOS-CAS [Institute of Semiconductors-Chinese Academy of Sciences] Beijing.

Starting with half day plenary sessions on 2D materials with guest plenary speaker Dr Aravind Vijayaraghavan from the National Graphene Institute in Manchester, UK, and on Quantum Information Processing with guest plenary speaker Prof David Cory from the Institute for Quantum Computing, University of Waterloo, Canada, Oxford Instruments’ seminar at the IOP in Beijing from 24-25th September [2014] promises to discuss cutting edge nanotechnology solutions for multiple applications.

A July 1, 2014 Oxford Instruments press release, which originated the news item, describes the sessions and provides more details about the speakers,

Two parallel sessions will focus on thin film processing, & materials characterisation, surface science and cryogenic environments and a wide range of topics will be covered within each technical area. These sessions will include guest international and Chinese speakers from renowned research institutions, speakers from the host institute, and technical experts from Oxford Instruments. This will also present an excellent opportunity for networking between all participants.

Confirmed speakers include the following, but more will be announced soon:

Dr. Aravind Vijayaraghavan, National Graphene Institute, Manchester, UK
Prof David Cory, Institute for Quantum Computing, University of Waterloo, Canada
Prof Guoxing Miao, Institute for Quantum Computing, University of Waterloo, Canada
Prof. HE Ke, Tsinghua University, Institute of Physics, CAS, China
Dr. WANG Xiaodong, Institute of Semiconductors, CAS, China
Prof Erwin Kessels, Tue Eindhoven, Netherlands
Prof. ZENG Yi, Institute of Semiconductor, CAS, China
Prof Robert Klie, University of Illinois Chicago, USA
Prof. Xinran WANG, Nanjing University, China
Prof. Zhihai CHENG, National Centre for Nanoscience and Technology, China
Prof. Yeliang WANG, Institute of Physics, CAS, China

The thin film processing sessions will review latest etch and deposition technological advances, including: ALD, Magnetron Sputtering, ICP PECVD, Nanoscale Etch, MEMS, MBE and more.

Materials characterisation, Surface Science and Cryogenic Environment sessions will cover multiple topics and technologies including: Ultra high vacuum SPM, Cryo free low temperature solutions, XPS/ESCA, an introduction to atomic force microscopy (AFM) and applications such as nanomechanics, In-situ heating and tensile characterisation using EBSD, Measuring Layer thicknesses and compositions using EDS, Nanomanipulation and fabrication within the SEM / FIB.

The host of last year’s Nanotechnology Tools seminar in India, Prof. Rudra Pratap, Chairperson at the Centre for Nano Science and Engineering, Indian Institute of Science, IISC Bangalore commented, “This seminar has been extremely well organised with competent speakers covering a variety of processes and tools for nanofabrication. It is great to have practitioners of the art give talks and provide tips and solutions based on their experience, something that cannot be found in text books.”

“This workshop is a great opportunity for a wide range of scientists in research and manufacturing to discover practical aspects of many new and established processes, technologies and applications, directly from renowned scientists and a leading manufacturer with over 50 years in the industry”, comments Mark Sefton, Sector Head of Oxford Instruments NanoSolutions, “Delegates appreciate the informal workshop atmosphere of these events, encouraging delegates to participate through open discussion and sharing their questions and experiences.”

This seminar is free of charge but prior booking is essential.

You can register on the Oxford Instruments website’s Bringing the Nanoworld Together Workshop webpage,

Memristors, memcapacitors, and meminductors for faster computers

While some call memristors a fourth fundamental component alongside resistors, capacitors, and inductors (as mentioned in my June 26, 2014 posting which featured an update of sorts on memristors [scroll down about 80% of the way]), others view memristors as members of an emerging periodic table of circuit elements (as per my April 7, 2010 posting).

It seems scientists, Fabio Traversa, and his colleagues fall into the ‘periodic table of circuit elements’ camp. From Traversa’s  June 27, 2014 posting on nanotechweb.org,

Memristors, memcapacitors and meminductors may retain information even without a power source. Several applications of these devices have already been proposed, yet arguably one of the most appealing is ‘memcomputing’ – a brain-inspired computing paradigm utilizing the ability of emergent nanoscale devices to store and process information on the same physical platform.

A multidisciplinary team of researchers from the Autonomous University of Barcelona in Spain, the University of California San Diego and the University of South Carolina in the US, and the Polytechnic of Turin in Italy, suggest a realization of “memcomputing” based on nanoscale memcapacitors. They propose and analyse a major advancement in using memcapacitive systems (capacitors with memory), as central elements for Very Large Scale Integration (VLSI) circuits capable of storing and processing information on the same physical platform. They name this architecture Dynamic Computing Random Access Memory (DCRAM).

Using the standard configuration of a Dynamic Random Access Memory (DRAM) where the capacitors have been substituted with solid-state based memcapacitive systems, they show the possibility of performing WRITE, READ and polymorphic logic operations by only applying modulated voltage pulses to the memory cells. Being based on memcapacitors, the DCRAM expands very little energy per operation. It is a realistic memcomputing machine that overcomes the von Neumann bottleneck and clearly exhibits intrinsic parallelism and functional polymorphism.

Here’s a link to and a citation for the paper,

Dynamic computing random access memory by F L Traversa, F Bonani, Y V Pershin, and M Di Ventra. Nanotechnology Volume 25 Number 28  doi:10.1088/0957-4484/25/28/285201 Published 27 June 2014

This paper is behind a paywall.

‘Scotch-tape’ technique for isolating graphene

The ‘scotch-tape’ technique is mythologized in the graphene origins story which has scientists, Andre Geim and Konstantin Novoselov, first isolating the material by using adhesive (aka ‘sticky’ tape or ‘scotch’ tape) as per my Oct. 7, 2010 posting,

The technique that Geim and Novoselov used to create the first graphene sheets both amuses and fascinates me (from the article by Kit Eaton on the Fast Company website),

The two scientists came up with the technique that first resulted in samples of graphene–peeling individual atoms-deep sheets of the material from a bigger block of pure graphite. The science here seems almost foolishly simple, but it took a lot of lateral thinking to dream up, and then some serious science to investigate: Geim and Novoselo literally “ripped” single sheets off the graphite by using regular adhesive tape. Once they’d confirmed they had grabbed micro-flakes of the material, Geim and Novoselo were responsible for some of the very early experiments into the material’s properties. Novel stuff indeed, but perhaps not so unexpected from a scientist (Geim) who the Nobel Committe notes once managed to make a frog levitate in a magnetic field.

A May 21, 2014 article about Geim who has won both a Nobel and an Ig Nobel (the only scientist to do so) and graphene by Sarah Lewis for Fast Company offers more details about the discovery,

The graphene FNE [Friday Night Experiments] began when Geim asked Da Jiang, a doctoral student from China, to polish a piece of graphite an inch across and a few millimeters thick down to 10 microns using a specialized machine. Partly due to a language barrier, Jiang polished the graphite down to dust, but not the ultimate thinness Geim wanted.

Helpfully, the Geim lab was also observing graphite using scanning tunneling microscopy (STM). The experimenters would clean the samples beforehand using Scotch tape, which they would then discard. “We took it out of the trash and just used it,” Novoselov said. The flakes of graphite on the tape from the waste bin were finer and thinner than what Jiang had found using the fancy machine. They weren’t one layer thick—that achievement came by ripping them some more with Scotch tape.

They swapped the adhesive for Japanese Nitto tape, “probably because the whole process is so simple and cheap we wanted to fancy it up a little and use this blue tape,” Geim said. Yet “the method is called the ‘Scotch tape technique.’ I fought against this name, but lost.”

Scientists elsewhere have been inspired to investigate the process in minute detail as per a June 27, 2014 news item on Nanowerk,

The simplest mechanical cleavage technique using a primitive “Scotch” tape has resulted in the Nobel-awarded discovery of graphenes and is currently under worldwide use for assembling graphenes and other two-dimensional (2D) graphene-like structures toward their utilization in novel high-performance nanoelectronic devices.

The simplicity of this method has initiated a booming research on 2D materials. However, the atomistic processes behind the micromechanical cleavage have still been poorly understood.

A June 27, 2014 MANA (International Center for Materials Nanoarchitectoinics) news release, which originated the news item, provides more information,

A joined team of experimentalists and theorists from the International Center for Young Scientists, International Center for Materials Nanoarchitectonics and Surface Physics and Structure Unit of the National Institute for Materials Science, National University of Science and Technology “MISiS” (Moscow, Russia), Rice University (USA) and University of Jyväskylä (Finland) led by Daiming Tang and Dmitri Golberg for the first time succeeded in complete understanding of physics, kinetics and energetics behind the regarded “Scotch-tape” technique using molybdenum disulphide (MoS2) atomic layers as a model material.

The researchers developed a direct in situ probing technique in a high-resolution transmission electron microscope (HRTEM) to investigate the mechanical cleavage processes and associated mechanical behaviors. By precisely manipulating an ultra-sharp metal probe to contact the pre-existing crystalline steps of the MoS2 single crystals, atomically thin flakes were delicately peeled off, selectively ranging from a single, double to more than 20 atomic layers. The team found that the mechanical behaviors are strongly dependent on the number of layers. Combination of in situ HRTEM and molecular dynamics simulations reveal a transformation of bending behavior from spontaneous rippling (< 5 atomic layers) to homogeneous curving (~ 10 layers), and finally to kinking (20 or more layers).

By considering the force balance near the contact point, the specific surface energy of a MoS2 monoatomic layer was calculated to be ~0.11 N/m. This is the first time that this fundamentally important property has directly been measured.

After initial isolation from the mother crystal, the MoS2 monolayer could be readily restacked onto the surface of the crystal, demonstrating the possibility of van der Waals epitaxy. MoS2 atomic layers could be bent to ultimate small radii (1.3 ~ 3.0 nm) reversibly without fracture. Such ultra-reversibility and extreme flexibility proves that they could be mechanically robust candidates for the advanced flexible electronic devices even under extreme folding conditions.

Here’s a link to and a citation for the research paper,

Nanomechanical cleavage of molybdenum disulphide atomic layers by Dai-Ming Tang, Dmitry G. Kvashnin, Sina Najmaei, Yoshio Bando, Koji Kimoto, Pekka Koskinen, Pulickel M. Ajayan, Boris I. Yakobson, Pavel B. Sorokin, Jun Lou, & Dmitri Golberg. Nature Communications 5, Article number: 3631 doi:10.1038/ncomms4631 Published 03 April 2014

This paper is behind a paywall but there is a free preview available through ReadCube Access.