Tag Archives: US

Mathematics, music, art, architecture, culture: Bridges 2015

Thanks to Alex Bellos and Tash Reith-Banks for their July 30, 2015 posting on the Guardian science blog network for pointing towards the Bridges 2015 conference,

The Bridges Conference is an annual event that explores the connections between art and mathematics. Here is a selection of the work being exhibited this year, from a Pi pie which vibrates the number pi onto your hand to delicate paper structures demonstrating number sequences. This year’s conference runs until Sunday in Baltimore (Maryland, US).

To whet your appetite, here’s the Pi pie (from the Bellos/Reith-Banks posting),

Pi Pie by Evan Daniel Smith Arduino, vibration motors, tinted silicone, pie tin “This pie buzzes the number pi onto your hand. I typed pi from memory into a computer while using a program I wrote to record it and send it to motors in the pie. The placement of the vibrations on the five fingers uses the structure of the Japanese soroban abacus, and bears a resemblance to Asian hand mnemonics.” Photograph: The Bridges Organisation

Pi Pie by Evan Daniel Smith
Arduino, vibration motors, tinted silicone, pie tin
“This pie buzzes the number pi onto your hand. I typed pi from memory into a computer while using a program I wrote to record it and send it to motors in the pie. The placement of the vibrations on the five fingers uses the structure of the Japanese soroban abacus, and bears a resemblance to Asian hand mnemonics.”
Photograph: The Bridges Organisation

You can find our more about Bridges 2015 here and should you be in the vicinity of Baltimore, Maryland, as a member of the public, you are invited to view the artworks on July 31, 2015,

July 29 – August 1, 2015 (Wednesday – Saturday)
Excursion Day: Sunday, August 2
A Collaborative Effort by
The University of Baltimore and Bridges Organization

A Five-Day Conference and Excursion
Wednesday, July 29 – Saturday, August 1
(Excursion Day on Sunday, August 2)

The Bridges Baltimore Family Day on Friday afternoon July 31 will be open to the Public to visit the BB Art Exhibition and participate in a series of events such as BB Movie Festival, and a series of workshops.

I believe the conference is being held at the University of Baltimore. Presumably, that’s where you’ll find the art show, etc.

Science diplomacy: high school age Pakistani students (terror attack survivors) attend NanoDiscovery Institute in New York State

The visiting students are from the Peshawar Army School in Pakistan, which suffered a terrorist attack in 2014. From the Peshawar School Massacre Wikipedia entry (Note: Links have been removed),

On 16 December 2014, seven gunmen affiliated with the Tehrik-i-Taliban (TTP) conducted a terrorist attack on the Army Public School in the northwestern Pakistani city of Peshawar. The militants, all of whom were foreign nationals, included one Chechen, three Arabs and two Afghans. They entered the school and opened fire on school staff and children,[8][9] killing 145 people, including 132 schoolchildren, ranging between eight and eighteen years of age.[10][11] A rescue operation was launched by the Pakistan Army’s Special Services Group (SSG) special forces, who killed all seven terrorists and rescued 960 people.[9][12][13] Chief military spokesman Major General Asim Bajwa said in a press conference that at least 130 people had been injured in the attack.[8]

As of July 29, 2015 seven of the student survivors are visiting New York State to attend a NanoDiscovery Institute program, according to a July 29, 2015 news item on Nanotechnology Now,

In support of Governor Andrew M. Cuomo’s commitment to provide high-tech educational opportunities in New York State, SUNY Polytechnic Institute’s Colleges of Nanoscale Science and Engineering (SUNY Poly CNSE), in partnership with Meridian International Center (Meridian) and with the support of the U.S. Embassy in Islamabad, today announced that SUNY Poly CNSE will host a group of students from Peshawar, Pakistan, from July 29 through August 4 [2015] at the institution’s world-class $20 billion Albany NanoTech Complex. The weeklong “NanoDiscovery Institute” will follow a custom-tailored curriculum designed to inspire the students with the limitless potential of the nanosciences. The students, who will take part in a number of nanotechnology-themed activities, presentations, and tours, survived a brutal attack on their school by terrorists last December when more than 140 students and teachers were killed in their classrooms.

A July 29, 2015 SUNY (State University of New York) Polytechnic Institute’s Colleges of Nanoscale Science and Engineering (SUNY Poly CNSE), news release, which originated the news item, describes the purpose of the visit to CNSE in more detail,

“Governor Andrew Cuomo’s innovation-based educational blueprint not only offers unprecedented opportunities for students in New York State, it also enables the exchange of scientific know-how far beyond its borders and we are thrilled to be able to host these students from Pakistan and engage and inspire them through the power of nanotechnology,” said Dr. Alain Kaloyeros, President and CEO of SUNY Poly. “It has been a pleasure to work with Meridian to create this positive educational experience for these students who have endured more in their young lives than most of us will see in a lifetime. We hope their visit will give them a greater understanding of the nanosciences, as well as an appreciation for America and New York State and our commitment to progress through education, the cornerstone of a better world.”

“We are proud to connect these science-oriented students from Pakistan with the globally recognized educational resources of SUNY Poly CNSE,” said Bonnie Glick, Senior Vice President of Meridian. “This exchange will expose these students to the nanotechnology world through a weeklong visit to SUNY Poly CNSE’s unmatched facilities. This is a perfect way to show Meridian’s mission in action as we seek to share ideas and engage people across borders and cultures to promote global leadership and to help to form future leaders. For these students in particular, this first-of-a-kind opportunity will not erase what happened, but we hope it will provide them with tools to enhance their educations and to foment global collaboration. Through the Nanotechnology Institute at SUNY Poly CNSE, these students will see, concretely, that there is more that unites us than divides us – science will be a powerful unifier.”

During their visit to SUNY Poly CNSE, the visiting Peshawar Army Public School students will create business plans as part of a Nanoeconomics course designed by SUNY Poly CNSE staff members, and they will also participate in nanotechnology career briefings. Two Pakistani high school teachers and a military liaison are accompanying the students as they attend the five-day NanoDiscovery Institute facilitated by SUNY Poly CNSE professors. Four students from the U.S. with similar academic interests will join the group, encouraging cross-cultural interactions. The group will become immersed in the nanosciences through hands on experiments and engaging presentations; they will learn how small a nanometer is and see first-hand New York State’s unique high-tech ecosystem to better understand what is underpinning technological progress and how an education focused on science, technology, engineering, and mathematics (STEM) can lead to exciting opportunities. As part of the U.S.-Pakistan Global Leadership and STEM program designed by Meridian to promote global collaboration through the sciences, the students will also engage in a global leadership skills training in Washington, D.C., and participate in cultural activities in New York City.

For a description of all of the activities planned for the students’ two week visit to the US, Shivani Gonzalez offers more detail in a July 29, 2015 article for timesunion.com,

“I am so thankful for this opportunity,” said Hammad, one of the students. (Organizers of the trip asked that the student’s last names not be used by the media.) “I know that this education will help us in the future.”

In December [2014[, the Peshawar school was attacked …

International outrage over the attack prompted the Pakistani government, which has been criticized for its lackluster pursuit of violent extremists, to strengthen its military and legal efforts.

The students are in the country for two weeks, and are being hosted by the Meridian International Center in Washington, D.C., where their packed itinerary began earlier this week. In addition to tours of the Pentagon and Capitol, the group met Secretary of State John Kerry.

After that [NanoDiscovery Institute], the students will go to the Baseball Hall of Fame in Cooperstown for a different kind of cultural exchange: The visitors will learn how to play baseball, and their U.S. counterparts will learn the fundamentals of cricket. A dual-sports tournament is planned.

The students will also visit West Point to see the similarities and differences with their military school back home.

To finish up the trip, the students will present their final nanotech projects to SUNY Poly staff, and will fly back to Washington to present the projects to U.S. military officials.

What a contrast for those students. In six months they go from surviving a terrorist attack at school to being part of a science diplomacy initiative where they are being ‘wined and dined’.

If you are interested in the Meridian International Center, there is this brief description at the end of the CNSE July 29, 2015 news release about the visit,

Meridian is a non-profit, non-partisan organization based in Washington, DC. For more than 50 years, Meridian has brought international visitors to the United States to engage with their counterparts in government, industry, academia, and civil society. Meridian promotes global leadership through the exchange of ideas, people, and culture. Meridian creates innovative education, cultural, and policy programs that strengthen U.S. engagement with the world through the power of exchange, that prepare public and private sector leaders for a complex global future, and that provide a neutral forum for international collaboration across sectors. For more information, visit meridian.org.

The Meridian website is strongly oriented to visual communication (lots of videos) which is a bit a disadvantage for me at the moment since my web browser, Firefox, has disabled Adobe Flash due to security concerns.

Replacing metal with nanocellulose paper

The quest to find uses for nanocellulose materials has taken a step forward with some work coming from the University of Maryland (US). From a July 24, 2015 news item on Nanowerk,

Researchers at the University of Maryland recently discovered that paper made of cellulose fibers is tougher and stronger the smaller the fibers get … . For a long time, engineers have sought a material that is both strong (resistant to non-recoverable deformation) and tough (tolerant of damage).

“Strength and toughness are often exclusive to each other,” said Teng Li, associate professor of mechanical engineering at UMD. “For example, a stronger material tends to be brittle, like cast iron or diamond.”

A July 23, 2015 University of Maryland news release, which originated the news item, provides details about the thinking which buttresses this research along with some details about the research itself,

The UMD team pursued the development of a strong and tough material by exploring the mechanical properties of cellulose, the most abundant renewable bio-resource on Earth. Researchers made papers with several sizes of cellulose fibers – all too small for the eye to see – ranging in size from about 30 micrometers to 10 nanometers. The paper made of 10-nanometer-thick fibers was 40 times tougher and 130 times stronger than regular notebook paper, which is made of cellulose fibers a thousand times larger.

“These findings could lead to a new class of high performance engineering materials that are both strong and tough, a Holy Grail in materials design,” said Li.

High performance yet lightweight cellulose-based materials might one day replace conventional structural materials (i.e. metals) in applications where weight is important. This could lead, for example, to more energy efficient and “green” vehicles. In addition, team members say, transparent cellulose nanopaper may become feasible as a functional substrate in flexible electronics, resulting in paper electronics, printable solar cells and flexible displays that could radically change many aspects of daily life.

Cellulose fibers can easily form many hydrogen bonds. Once broken, the hydrogen bonds can reform on their own—giving the material a ‘self-healing’ quality. The UMD discovered that the smaller the cellulose fibers, the more hydrogen bonds per square area. This means paper made of very small fibers can both hold together better and re-form more quickly, which is the key for cellulose nanopaper to be both strong and tough.

“It is helpful to know why cellulose nanopaper is both strong and tough, especially when the underlying reason is also applicable to many other materials,” said Liangbing Hu, assistant professor of materials science at UMD.

To confirm, the researchers tried a similar experiment using carbon nanotubes that were similar in size to the cellulose fibers. The carbon nanotubes had much weaker bonds holding them together, so under tension they did not hold together as well. Paper made of carbon nanotubes is weak, though individually nanotubes are arguably the strongest material ever made.

One possible future direction for the research is the improvement of the mechanical performance of carbon nanotube paper.

“Paper made of a network of carbon nanotubes is much weaker than expected,” said Li. “Indeed, it has been a grand challenge to translate the superb properties of carbon nanotubes at nanoscale to macroscale. Our research findings shed light on a viable approach to addressing this challenge and achieving carbon nanotube paper that is both strong and tough.”

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

Anomalous scaling law of strength and toughness of cellulose nanopaper by Hongli Zhu, Shuze Zhu, Zheng Jia, Sepideh Parvinian, Yuanyuan Li, Oeyvind Vaaland, Liangbing Hu, and Teng Li. PNAS (Proceedings of the National Academy of Sciences) July 21, 2015 vol. 112 no. 29 doi: 10.1073/pnas.1502870112

This paper is behind a paywall.

There is a lot of research on applications for nanocellulose, everywhere it seems, except Canada, which at one time was a leader in the business of producing cellulose nanocrystals (CNC).

Here’s a sampling of some of my most recent posts on nanocellulose,

Nanocellulose as a biosensor (July 28, 2015)

Microscopy, Paper and Fibre Research Institute (Norway), and nanocellulose (July 8, 2015)

Nanocellulose markets report released (June 5, 2015; US market research)

New US platform for nanocellulose and occupational health and safety research (June 1, 2015; Note: As you find new applications, you need to concern yourself with occupational health and safety.)

‘Green’, flexible electronics with nanocellulose materials (May 26, 2015; research from China)

Treating municipal wastewater and dirty industry byproducts with nanocellulose-based filters (Dec. 23, 2014; research from Sweden)

Nanocellulose and an intensity of structural colour (June 16, 2014; research about replacing toxic pigments with structural colour from the UK)

I ask again, where are the Canadians? If anybody has an answer, please let me know.

Canada and a mandatory survey on nanomaterials due February 2016

If memory serves, this is the second nanomaterials reporting survey that the Canadian federal government has requested in the seven years that I’ve blogging on the topic Canadian nanotechnology. (As usual, I’ve gotten my information from a source outside the country.) Thanks to Lynn Bergeson (US lawyer) and her July 27, 2015 posting on Nanotechnology Now where she covers nanotechnology’s regulatory developments (Note: A link has been removed),

The July 25, 2015, Canada Gazette includes a notice announcing that the Minister of the Environment requires, for the purpose of assessing whether the substances described in the notice are toxic or are capable of becoming toxic, or for the purpose of assessing whether to control, or the manner in which to control the listed substances, any person described in the notice who possesses or who may reasonably be expected to have access to the information required to provide that information. See http://www.gazette.gc.ca/rp-pr/p1/2015/2015-07-25/html/notice-avis-eng.php The notice applies to a substance that has a size of between 1 and 100 nanometers in at least one external dimension, or internal or surface structure; and is provided in the list in Schedule 1 of the notice. The list includes over 200 substances. The notice applies to any person who, during the 2014 calendar year, manufactured a total quantity greater than 100 kilograms (kg) of a substance set out in Schedule 1. …

You can find the Canada Gazette notice (Notice with respect to certain nanomaterials in Canadian commerce) here: http://www.gazette.gc.ca/rp-pr/p1/2015/2015-07-25/html/notice-avis-eng.php but you may find the Guidance for responding to the Notice: http://www.ec.gc.ca/ese-ees/default.asp?lang=En&n=AACFB2C0-1 more helpful (Note: Links have been removed),

1.1- Purpose of the Notice

In 2011, the Canada-United States Regulatory Cooperation Council (RCC) Nanotechnology InitiativeFootnote[1] was launched to increase alignment in regulatory approaches for nanomaterials between Canada and the US to reduce risk to human health and the environment; to promote sharing of scientific and regulatory expertise; and to foster innovation. Completed in February 2014, the RCC Nanotechnology Initiative included a work element on Commercial Information.Footnote[2] This work element was aimed at increasing knowledge of commercial uses of nanomaterials in Canada and the US. The primary output from this work element was a Nanomaterials Use Matrix which identified nanomaterials by type and use category based on the most up-to-date information, at the time, on commercially available nanomaterials. The nanomaterial types were cross-referenced with the DSL to identify nanomaterials which could be considered existing in Canada. The result is a preliminary reference list and may not be comprehensive of all nanomaterials. Ongoing engagement with stakeholders through voluntary initiatives and other fora will inform further development of the list of existing nanomaterials in Canada.

The purpose of the Notice is to gather information on 206 nanomaterials identified as potentially in commerce in Canada from the primary reference list. [emphasis mine] The information collected from the Notice will support the development of a list of nanomaterials in commerce in Canada by confirming their commercial status, and subsequent prioritization activities for these substances, which may include risk assessment and risk management activities, if required. This will ensure that future decision making is based on the best available information.

The list of reportable substances is long and not alphabetized but before you check you may want to review this,

2.1- Reporting criteria

To determine whether a company is required to respond, the following factors must be considered:

Type of substance (i.e., nanoscale form)
Type of activity
Calendar year
Quantity
The quantity should be determined based on the quantity of the substance itself at the nanoscale, and not on the quantity of the product or mixture containing the substance.

The purpose of the Notice is to gather information on nanomaterials in commerce in Canada. A response is only required if the conditions set out in Schedule 1 and Schedule 2 of the notice are met.

The Notice applies to any person who, during the 2014 calendar year [emphasis mine], satisfied any of the following criteria:

Manufactured a total quantity greater than 100 kg of a substance listed in Schedule 1 that is at the nanoscale.
Imported a total quantity greater than 100 kg of a substance listed in Schedule 1 that is at the nanoscale, at any concentration, whether alone, in a mixture or in a product.

The reporting threshold of 100 kg is based on activity with the substance in the nanoscale (i.e. you manufacture, or imported a total quantity greater than 100 kg of a substance with a size between 1 and 100 nanometres, inclusive, in at least one external dimension, or internal or surface structure).

Your response to the information requested should also be based on activities with the substance in the nanoscale.

If you are engaged with a substance that is not in the nanoscale (i.e. same CAS RN, but not nanoscale) and would like to identify yourself as a stakeholder for that substance, you may submit a Declaration of Stakeholder Interest (see section 7 of this document).

You may find this flowchart (from the guidance webpage), useful,

Figure 1:  Reporting Diagram for Nanomaterials [downloaded from: http://www.ec.gc.ca/ese-ees/default.asp?lang=En&n=AACFB2C0-1]

Figure 1: Reporting Diagram for Nanomaterials [downloaded from: http://www.ec.gc.ca/ese-ees/default.asp?lang=En&n=AACFB2C0-1]

The information you provide needs to cover the 2014 calendar year and is due,

10. Responding to the Notice

Responses to the Notice must be provided no later than February 23, 2016, 5 p.m. Eastern Standard Time using the online reporting system available through Environment Canada’s Single Window available from the Chemical Substances Web site.

Good luck to all those who must report.

Nanomaterials and UV (ultraviolet) light for environmental cleanups

I think this is the first time I’ve seen anything about a technology that removes toxic materials from both water and soil; it’s usually one or the other. A July 22, 2015 news item on Nanowerk makes the announcement (Note: A link has been removed),

Many human-made pollutants in the environment resist degradation through natural processes, and disrupt hormonal and other systems in mammals and other animals. Removing these toxic materials — which include pesticides and endocrine disruptors such as bisphenol A (BPA) — with existing methods is often expensive and time-consuming.

In a new paper published this week in Nature Communications (“Nanoparticles with photoinduced precipitation for the extraction of pollutants from water and soil”), researchers from MIT [Massachusetts Institute of Technology] and the Federal University of Goiás in Brazil demonstrate a novel method for using nanoparticles and ultraviolet (UV) light to quickly isolate and extract a variety of contaminants from soil and water.

A July 21, 2015 MIT news release by Jonathan Mingle, which originated the news item, describes the inspiration and the research in more detail,

Ferdinand Brandl and Nicolas Bertrand, the two lead authors, are former postdocs in the laboratory of Robert Langer, the David H. Koch Institute Professor at MIT’s Koch Institute for Integrative Cancer Research. (Eliana Martins Lima, of the Federal University of Goiás, is the other co-author.) Both Brandl and Bertrand are trained as pharmacists, and describe their discovery as a happy accident: They initially sought to develop nanoparticles that could be used to deliver drugs to cancer cells.

Brandl had previously synthesized polymers that could be cleaved apart by exposure to UV light. But he and Bertrand came to question their suitability for drug delivery, since UV light can be damaging to tissue and cells, and doesn’t penetrate through the skin. When they learned that UV light was used to disinfect water in certain treatment plants, they began to ask a different question.

“We thought if they are already using UV light, maybe they could use our particles as well,” Brandl says. “Then we came up with the idea to use our particles to remove toxic chemicals, pollutants, or hormones from water, because we saw that the particles aggregate once you irradiate them with UV light.”

A trap for ‘water-fearing’ pollution

The researchers synthesized polymers from polyethylene glycol, a widely used compound found in laxatives, toothpaste, and eye drops and approved by the Food and Drug Administration as a food additive, and polylactic acid, a biodegradable plastic used in compostable cups and glassware.

Nanoparticles made from these polymers have a hydrophobic core and a hydrophilic shell. Due to molecular-scale forces, in a solution hydrophobic pollutant molecules move toward the hydrophobic nanoparticles, and adsorb onto their surface, where they effectively become “trapped.” This same phenomenon is at work when spaghetti sauce stains the surface of plastic containers, turning them red: In that case, both the plastic and the oil-based sauce are hydrophobic and interact together.

If left alone, these nanomaterials would remain suspended and dispersed evenly in water. But when exposed to UV light, the stabilizing outer shell of the particles is shed, and — now “enriched” by the pollutants — they form larger aggregates that can then be removed through filtration, sedimentation, or other methods.

The researchers used the method to extract phthalates, hormone-disrupting chemicals used to soften plastics, from wastewater; BPA, another endocrine-disrupting synthetic compound widely used in plastic bottles and other resinous consumer goods, from thermal printing paper samples; and polycyclic aromatic hydrocarbons, carcinogenic compounds formed from incomplete combustion of fuels, from contaminated soil.

The process is irreversible and the polymers are biodegradable, minimizing the risks of leaving toxic secondary products to persist in, say, a body of water. “Once they switch to this macro situation where they’re big clumps,” Bertrand says, “you won’t be able to bring them back to the nano state again.”

The fundamental breakthrough, according to the researchers, was confirming that small molecules do indeed adsorb passively onto the surface of nanoparticles.

“To the best of our knowledge, it is the first time that the interactions of small molecules with pre-formed nanoparticles can be directly measured,” they write in Nature Communications.

Nano cleansing

Even more exciting, they say, is the wide range of potential uses, from environmental remediation to medical analysis.

The polymers are synthesized at room temperature, and don’t need to be specially prepared to target specific compounds; they are broadly applicable to all kinds of hydrophobic chemicals and molecules.

“The interactions we exploit to remove the pollutants are non-specific,” Brandl says. “We can remove hormones, BPA, and pesticides that are all present in the same sample, and we can do this in one step.”

And the nanoparticles’ high surface-area-to-volume ratio means that only a small amount is needed to remove a relatively large quantity of pollutants. The technique could thus offer potential for the cost-effective cleanup of contaminated water and soil on a wider scale.

“From the applied perspective, we showed in a system that the adsorption of small molecules on the surface of the nanoparticles can be used for extraction of any kind,” Bertrand says. “It opens the door for many other applications down the line.”

This approach could possibly be further developed, he speculates, to replace the widespread use of organic solvents for everything from decaffeinating coffee to making paint thinners. Bertrand cites DDT, banned for use as a pesticide in the U.S. since 1972 but still widely used in other parts of the world, as another example of a persistent pollutant that could potentially be remediated using these nanomaterials. “And for analytical applications where you don’t need as much volume to purify or concentrate, this might be interesting,” Bertrand says, offering the example of a cheap testing kit for urine analysis of medical patients.

The study also suggests the broader potential for adapting nanoscale drug-delivery techniques developed for use in environmental remediation.

“That we can apply some of the highly sophisticated, high-precision tools developed for the pharmaceutical industry, and now look at the use of these technologies in broader terms, is phenomenal,” says Frank Gu, an assistant professor of chemical engineering at the University of Waterloo in Canada, and an expert in nanoengineering for health care and medical applications.

“When you think about field deployment, that’s far down the road, but this paper offers a really exciting opportunity to crack a problem that is persistently present,” says Gu, who was not involved in the research. “If you take the normal conventional civil engineering or chemical engineering approach to treating it, it just won’t touch it. That’s where the most exciting part is.”

The researchers have made this illustration of their work available,

Nanoparticles that lose their stability upon irradiation with light have been designed to extract endocrine disruptors, pesticides, and other contaminants from water and soils. The system exploits the large surface-to-volume ratio of nanoparticles, while the photoinduced precipitation ensures nanomaterials are not released in the environment. Image: Nicolas Bertrand Courtesy: MIT

Nanoparticles that lose their stability upon irradiation with light have been designed to extract endocrine disruptors, pesticides, and other contaminants from water and soils. The system exploits the large surface-to-volume ratio of nanoparticles, while the photoinduced precipitation ensures nanomaterials are not released in the environment.
Image: Nicolas Bertrand Courtesy: MIT

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

Nanoparticles with photoinduced precipitation for the extraction of pollutants from water and soil by Ferdinand Brandl, Nicolas Bertrand, Eliana Martins Lima & Robert Langer. Nature Communications 6, Article number: 7765 doi:10.1038/ncomms8765 Published 21 July 2015

This paper is open access.

Carbon sequestration and buckyballs (aka C60 or buckminsterfullerenes)

Sometime in the last few years I was asked about carbon sequestration (or carbon capture) and nanotechnology and had no answer for the question until now (drat!). A July 13, 2015 Rice University (Texas, US) news release (also on EurekAlert) describes some research into buckyballs and the possibility they could be used to confine greenhouse gases,

Rice University scientists are forging toward tunable carbon-capture materials with a new study that shows how chemical changes affect the abilities of enhanced buckyballs to confine greenhouse gases.

The lab of Rice chemist Andrew Barron found last year that carbon-60 molecules (aka buckyballs, discovered at Rice in the 1980s) gain the ability to sequester carbon dioxide when combined with a polymer known as polyethyleneimine (PEI).

Two critical questions – how and how well – are addressed in a new paper in the American Chemical Society journal Energy and Fuels.

The news release expands on the theme,

The amine-rich combination of C60 and PEI showed its potential in the previous study to capture emissions of carbon dioxide, a greenhouse gas, from such sources as industrial flue gases and natural-gas wells.

In the new study, the researchers found pyrolyzing the material – heating it in an oxygen-free environment – changes its chemical composition in ways that may someday be used to tune what the scientists call PEI-C60 for specific carbon-capture applications.

“One of the things we wanted to see is at what point, chemically, it converts from being something that absorbed best at high temperature to something that absorbed best at low temperature,” Barron said. “In other words, at what point does the chemistry change from one to the other?”

Lead author Enrico Andreoli pyrolyzed PEI-C60 in argon at various temperatures from 100 to 1,000 degrees Celsius (212 to 1,832 degrees Fahrenheit) and then evaluated each batch for carbon uptake.

He discovered the existence of a transition point at 200 C, a boundary between the material’s ability to soak in carbon dioxide through chemical means as opposed to physical absorption.

The material that was pyrolyzed at low temperatures became gooey and failed at pulling in carbon from high-temperature sources by chemical means. The opposite was true for PEI-C60 pyrolyzed at high heat. The now-porous, brittle material became better in low-temperature environments, physically soaking up carbon dioxide molecules.

At 200 C, they found the heat treatment breaks the polymer’s carbon-nitrogen bonds, leading to a drastic decrease in carbon capture by any means.

“One of the goals was to see if can we make this a little less gooey and still have chemical uptake, and the answer is, not really,” Barron said. “It flips from one process to the other. But this does give us a nice continuum of how to get from one to the other.”

Andreoli found that at its peak, untreated PEI-C60 absorbed more than a 10th of its weight in carbon dioxide at high temperatures (0.13 grams per gram of material at 90 C). Pyrolyzed PEI-C60 did nearly as well at low temperatures (0.12 grams at 25 C).

The researchers, with an eye on potential environmental benefits, continue to refine their process. “This has definitely pointed us in the right direction,” Barron said.

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

Correlating Carbon Dioxide Capture and Chemical Changes in Pyrolyzed Polyethylenimine-C60 by Enrico Andreoli and Andrew R. Barron. Energy Fuels, Article ASAP DOI: 10.1021/acs.energyfuels.5b00778 Publication Date (Web): July 2, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Greening silver nanoparticles with lignin

A July 13, 2015 news item on phys.org highlights a new approach to making silver nanoparticles safer in the environment,

North Carolina State University researchers have developed an effective and environmentally benign method to combat bacteria by engineering nanoscale particles that add the antimicrobial potency of silver to a core of lignin, a ubiquitous substance found in all plant cells. The findings introduce ideas for better, greener and safer nanotechnology and could lead to enhanced efficiency of antimicrobial products used in agriculture and personal care.

A July 13, 2015 North Carolina State University (NCSU) news release (also on EurekAlert), which originated the news item, adds a bit more information,

As the nanoparticles wipe out the targeted bacteria, they become depleted of silver. The remaining particles degrade easily after disposal because of their biocompatible lignin core, limiting the risk to the environment.

“People have been interested in using silver nanoparticles for antimicrobial purposes, but there are lingering concerns about their environmental impact due to the long-term effects of the used metal nanoparticles released in the environment,” said Velev, INVISTA Professor of Chemical and Biomolecular Engineering at NC State and the paper’s corresponding author. “We show here an inexpensive and environmentally responsible method to make effective antimicrobials with biomaterial cores.”

The researchers used the nanoparticles to attack E. coli, a bacterium that causes food poisoning; Pseudomonas aeruginosa, a common disease-causing bacterium; Ralstonia, a genus of bacteria containing numerous soil-borne pathogen species; and Staphylococcus epidermis, a bacterium that can cause harmful biofilms on plastics – like catheters – in the human body. The nanoparticles were effective against all the bacteria.

The method allows researchers the flexibility to change the nanoparticle recipe in order to target specific microbes. Alexander Richter, the paper’s first author and an NC State Ph.D. candidate who won a 2015 Lemelson-MIT prize, says that the particles could be the basis for reduced risk pesticide products with reduced cost and minimized environmental impact.

“We expect this method to have a broad impact,” Richter said. “We may include less of the antimicrobial ingredient without losing effectiveness while at the same time using an inexpensive technique that has a lower environmental burden. We are now working to scale up the process to synthesize the particles under continuous flow conditions.”

I don’t quite understand how the silver nanoparticles/ions are rendered greener. I gather the lignin is harmless but where do the silver nanoparticles/ions go after they’ve been stripped of their lignin cover and have killed the bacteria? I did try reading the paper’s abstract (not much use for someone with my science level),

Silver nanoparticles have antibacterial properties, but their use has been a cause for concern because they persist in the environment. Here, we show that lignin nanoparticles infused with silver ions and coated with a cationic polyelectrolyte layer form a biodegradable and green alternative to silver nanoparticles. The polyelectrolyte layer promotes the adhesion of the particles to bacterial cell membranes and, together with silver ions, can kill a broad spectrum of bacteria, including Escherichia coli, Pseudomonas aeruginosa and quaternary-amine-resistant Ralstonia sp. Ion depletion studies have shown that the bioactivity of these nanoparticles is time-limited because of the desorption of silver ions. High-throughput bioactivity screening did not reveal increased toxicity of the particles when compared to an equivalent mass of metallic silver nanoparticles or silver nitrate solution. Our results demonstrate that the application of green chemistry principles may allow the synthesis of nanoparticles with biodegradable cores that have higher antimicrobial activity and smaller environmental impact than metallic silver nanoparticles.

If you can explain what happens to the silver nanoparticles, please let me know.

Meanwhile, here’s a link to and a citation for the paper,

An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core by Alexander P. Richter, Joseph S. Brown, Bhuvnesh Bharti, Amy Wang, Sumit Gangwal, Keith Houck, Elaine A. Cohen Hubal, Vesselin N. Paunov, Simeon D. Stoyanov, & Orlin D. Velev. Nature Nanotechnology (2015) doi:10.1038/nnano.2015.141 Published online 13 July 2015

This paper is behind a paywall.

Nanoscale device emits light as powerfully as an object 10,000 times its size

The potential application in the field of solar power is what most interests me in this collaborative research from the University of Wisconsin-Madison (US) and Fudan University in China. From a July 13, 2015 news item on ScienceDaily,

University of Wisconsin-Madison engineers have created a nanoscale device that can emit light as powerfully as an object 10,000 times its size. It’s an advance that could have huge implications for everything from photography to solar power.

In a paper published July 10 [2015] in the journal Physical Review Letters, Zongfu Yu, an assistant professor of electrical and computer engineering, and his collaborators describe a nanoscale device that drastically surpasses previous technology in its ability to scatter light. They showed how a single nanoresonator can manipulate light to cast a very large “reflection.” The nanoresonator’s capacity to absorb and emit light energy is such that it can make itself — and, in applications, other very small things — appear 10,000 times as large as its physical size.

A July 13, 2015 University of Wisconsin-Madison news release (also on EurekAlert) by Scott Gordon, which originated the news item, expands on the theme,

“Making an object look 10,000 times larger than its physical size has lots of implications in technologies related to light,” Yu says.

The researchers realized the advance through materials innovation and a keen understanding of the physics of light. Much like sound, light can resonate, amplifying itself as the surrounding environment manipulates the physical properties of its wave energy. The researchers took advantage of this by creating an artificial material in which the wavelength of light is much larger than in a vacuum, which allows light waves to resonate more powerfully.

The device condenses light to a size smaller than its wavelength, meaning it can gather a lot of light energy, and then scatters the light over a very large area, harnessing its output for imaging applications that make microscopic particles appear huge.

“The device makes an object super-visible by enlarging its optical appearance with this super-strong scattering effect,” says Ming Zhou, a Ph.D. student in Yu’s group and lead author of the paper.

Much as a very thin string on a guitar can absorb a large amount of acoustic energy from its surroundings and begin to vibrate in sympathy, this one very small optical device can receive light energy from all around and yield a surprisingly strong output. In imaging, this presents clear advantages over conventional lenses, whose light-gathering capacity is limited by direction and size.

“We are developing photodetectors based on this technology and, for example, it could be helpful for photographers wanting to shoot better quality pictures in weak light conditions,” Yu says.

Given the nanoresonator’s capacity to absorb large amounts of light energy, the technology also has potential in applications that harvest the sun’s energy with high efficiency. In addition, Yu envisions simply letting the resonator emit that energy in the form of infrared light toward the sky, which is very cold. Because the nanoresonator has a large optical cross-section — that is, an ability to emit light that dramatically exceeds its physical size — it can shed a lot of heat energy, making for a passive cooling system.

“This research opens up a new way to manipulate the flow of light, and could enable new technologies in light sensing and solar energy conversion,” Yu says.

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

Extraordinarily Large Optical Cross Section for Localized Single Nanoresonator by Ming Zhou, Lei Shi, Jian Zi, and Zongfu Yu. Phys. Rev. Lett. 115, 023903  DOI: http://dx.doi.org/10.1103/PhysRevLett.115.023903 Published 10 July 2015

This paper is behind a paywall.

SINGLE (3D Structure Identification of Nanoparticles by Graphene Liquid Cell Electron Microscopy) and the 3D structures of two individual platinum nanoparticles in solution

It seems to me there’s been an explosion of new imaging techniques lately. This one from the Lawrence Berkelely National Laboratory is all about imaging colloidal nanoparticles (nanoparticles in solution), from a July 20, 2015 news item on Azonano,

Just as proteins are one of the basic building blocks of biology, nanoparticles can serve as the basic building blocks for next generation materials. In keeping with this parallel between biology and nanotechnology, a proven technique for determining the three dimensional structures of individual proteins has been adapted to determine the 3D structures of individual nanoparticles in solution.

A multi-institutional team of researchers led by the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab), has developed a new technique called “SINGLE” that provides the first atomic-scale images of colloidal nanoparticles. SINGLE, which stands for 3D Structure Identification of Nanoparticles by Graphene Liquid Cell Electron Microscopy, has been used to separately reconstruct the 3D structures of two individual platinum nanoparticles in solution.

A July 16, 2015 Berkeley Lab news release, which originated the news item, reveals more details about the reason for the research and the research itself,

“Understanding structural details of colloidal nanoparticles is required to bridge our knowledge about their synthesis, growth mechanisms, and physical properties to facilitate their application to renewable energy, catalysis and a great many other fields,” says Berkeley Lab director and renowned nanoscience authority Paul Alivisatos, who led this research. “Whereas most structural studies of colloidal nanoparticles are performed in a vacuum after crystal growth is complete, our SINGLE method allows us to determine their 3D structure in a solution, an important step to improving the design of nanoparticles for catalysis and energy research applications.”

Alivisatos, who also holds the Samsung Distinguished Chair in Nanoscience and Nanotechnology at the University of California Berkeley, and directs the Kavli Energy NanoScience Institute at Berkeley (Kavli ENSI), is the corresponding author of a paper detailing this research in the journal Science. The paper is titled “3D Structure of Individual Nanocrystals in Solution by Electron Microscopy.” The lead co-authors are Jungwon Park of Harvard University, Hans Elmlund of Australia’s Monash University, and Peter Ercius of Berkeley Lab. Other co-authors are Jong Min Yuk, David Limmer, Qian Chen, Kwanpyo Kim, Sang Hoon Han, David Weitz and Alex Zettl.

Colloidal nanoparticles are clusters of hundreds to thousands of atoms suspended in a solution whose collective chemical and physical properties are determined by the size and shape of the individual nanoparticles. Imaging techniques that are routinely used to analyze the 3D structure of individual crystals in a material can’t be applied to suspended nanomaterials because individual particles in a solution are not static. The functionality of proteins are also determined by their size and shape, and scientists who wanted to image 3D protein structures faced a similar problem. The protein imaging problem was solved by a technique called “single-particle cryo-electron microscopy,” in which tens of thousands of 2D transmission electron microscope (TEM) images of identical copies of an individual protein or protein complex frozen in random orientations are recorded then computationally combined into high-resolution 3D reconstructions. Alivisatos and his colleagues utilized this concept to create their SINGLE technique.

“In materials science, we cannot assume the nanoparticles in a solution are all identical so we needed to develop a hybrid approach for reconstructing the 3D structures of individual nanoparticles,” says co-lead author of the Science paper Peter Ercius, a staff scientist with the National Center for Electron Microscopy (NCEM) at the Molecular Foundry, a DOE Office of Science User Facility.

“SINGLE represents a combination of three technological advancements from TEM imaging in biological and materials science,” Ercius says. “These three advancements are the development of a graphene liquid cell that allows TEM imaging of nanoparticles rotating freely in solution, direct electron detectors that can produce movies with millisecond frame-to-frame time resolution of the rotating nanocrystals, and a theory for ab initio single particle 3D reconstruction.”

The graphene liquid cell (GLC) that helped make this study possible was also developed at Berkeley Lab under the leadership of Alivisatos and co-author Zettl, a physicist who also holds joint appointments with Berkeley Lab, UC Berkeley and Kavli ENSI. TEM imaging uses a beam of electrons rather than light for illumination and magnification but can only be used in a high vacuum because molecules in the air disrupt the electron beam. Since liquids evaporate in high vacuum, samples in solutions must be hermetically sealed in special solid containers – called cells – with a very thin viewing window before being imaged with TEM. In the past, liquid cells featured silicon-based viewing windows whose thickness limited resolution and perturbed the natural state of the sample materials. The GLC developed at Berkeley lab features a viewing window made from a graphene sheet that is only a single atom thick.

“The GLC provides us with an ultra-thin covering of our nanoparticles while maintaining liquid conditions in the TEM vacuum,” Ercius says. “Since the graphene surface of the GLC is inert, it does not adsorb or otherwise perturb the natural state of our nanoparticles.”

Working at NCEM’s TEAM I, the world’s most powerful electron microscope, Ercius, Alivisatos and their colleagues were able to image in situ the translational and rotational motions of individual nanoparticles of platinum that were less than two nanometers in diameter. Platinum nanoparticles were chosen because of their high electron scattering strength and because their detailed atomic structure is important for catalysis.

“Our earlier GLC studies of platinum nanocrystals showed that they grow by aggregation, resulting in complex structures that are not possible to determine by any previously developed method,” Ercius says. “Since SINGLE derives its 3D structures from images of individual nanoparticles rotating freely in solution, it enables the analysis of heterogeneous populations of potentially unordered nanoparticles that are synthesized in solution, thereby providing a means to understand the structure and stability of defects at the nanoscale.”

The next step for SINGLE is to recover a full 3D atomic resolution density map of colloidal nanoparticles using a more advanced camera installed on TEAM I that can provide 400 frames-per-second and better image quality.

“We plan to image defects in nanoparticles made from different materials, core shell particles, and also alloys made of two different atomic species,” Ercius says. [emphasis mine]

“Two different atomic species?”, they really are pushing that biology analogy.

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

3D structure of individual nanocrystals in solution by electron microscopy by Jungwon Park, Hans Elmlund, Peter Ercius, Jong Min Yuk, David T. Limme, Qian Chen, Kwanpyo Kim, Sang Hoon Han, David A. Weitz, A. Zettl, A. Paul Alivisatos. Science 17 July 2015: Vol. 349 no. 6245 pp. 290-295 DOI: 10.1126/science.aab1343

This paper is behind a paywall.

Kill bacterial biofilms and activate healing with cinnamon and peppermint

These compounds based on peppermint and cinnamon kill infection (bacterial biofilm) while helping the wound to heal according to a July 8, 2015 news item on ScienceDaily,

Infectious colonies of bacteria called biofilms that develop on chronic wounds and medical devices can cause serious health problems and are tough to treat. But now scientists have found a way to package antimicrobial compounds from peppermint and cinnamon in tiny capsules that can both kill biofilms and actively promote healing. The researchers say the new material could be used as a topical antibacterial treatment and disinfectant.

A July 8, 2015 American Chemical Society news release on EurekAlert, which originated the news item, provides more detail,

Many bacteria clump together in sticky plaques in a way that makes them difficult to eliminate with traditional antibiotics. Doctors sometimes recommend cutting out infected tissues. This approach is costly, however, and because it’s invasive, many patients opt out of treatment altogether. Essential oils and other natural compounds have emerged recently as alternative substances that can get rid of pathogenic bacteria, but researchers have had a hard time translating their antibacterial activity into treatments. Vincent M. Rotello and colleagues wanted to address this challenge.

The researchers packaged peppermint oil and cinnamaldehyde, the compound in cinnamon responsible for its flavor and aroma, into silica nanoparticles. The microcapsule treatment was effective against four different types of bacteria, including one antibiotic-resistant strain. It also promoted the growth of fibroblasts, a cell type that is important in wound healing.

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

Nanoparticle-Stabilized Capsules for the Treatment of Bacterial Biofilms by Bradley Duncan, Xiaoning Li, Ryan F. Landis, Sung Tae Kim, Akash Gupta, Li-Sheng Wang, Rajesh Ramanathan, Rui Tang, Jeffrey A. Boerth, and Vincent M. Rotello. ACS Nano, Article ASAP
DOI: 10.1021/acsnano.5b01696 Publication Date (Web): June 17, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.