Monthly Archives: July 2018

A gripping problem: tree frogs lead the way

Courtesy: University of Glasgow

At least once a year, there must be a frog posting here (ETA: July 31, 2018 at 1640 hours: unusually, this is my second ‘frog’ posting in one week; my July 26, 2018 posting concerns a very desperate frog, Romeo). Prior to Romeo, this March 15, 2018 news item on tickled my fancy,

Scientists researching how tree frogs climb have discovered that a unique combination of adhesion and grip gives them perfect technique.

The new research, led by the University of Glasgow and published today [March 15, 2018] in the Journal of Experimental Biology, could have implications for areas of science such as robotics, as well as the production of climbing equipment and even tyre manufacture.

A March 15, 2018 University of Glasgow press release, which originated the news item, provides a little more detail,

Researchers found that, using their fluid-filled adhesive toe pads, tree frogs are able to grip to surfaces to climb. When surfaces aren’t smooth enough to allow adhesion, researchers found that the frogs relied on their long limbs to grip around objects.

University of Glasgow scientists Iain Hill and Jon Barnes gave the tree frogs a series of narrow and wide cylinders to climb. The research team found that on the narrow cylinders the frogs used their grip and adhesion pads, allowing them to climb the obstacle at speed. Wider cylinders were too large for the frogs to grip, so they could only climb more slowly using their suction adhesive pads.

When the cylinders were coated in sandpaper, preventing adhesion, the frogs could only climb the narrow ones slowly, using their grip. They were not able to climb the wider cylinders covered in sandpaper as they couldn’t use their grip or adhesion.

Dr Barnes said: “I have worked on tree frog research for many years and I find them fascinating. Work on tree frogs has been of interest to industry and other areas of science in the past, since their climbing abilities can offer us insights into the most efficient way to climb and stick to surfaces.

“Climbing robots, for instance, need ways to stick, they could be based either on gecko climbing or tree frog climbing.  This research demonstrates how a good climbing robot would need to combine gripping and adhesion to climb more efficiently.”

The study, “The biomechanics of tree frogs climbing curved surfaces: a gripping problem” is published in the Journal ofExperimental Biology. The work was funded by the Royal Society, London and by grants from the National Natural Science Foundation of China and the Natural Science Foundation of Jiangsu Province.

Here’s a link to and a citation for the paper (I love the pun in the title),

The biomechanics of tree frogs climbing curved surfaces: a gripping problem by Iain D. C. Hill, Benzheng Dong, W. Jon. P. Barnes, Aihong Ji, Thomas Endlein. Journal of Experimental Biology 2018 : jeb.168179 doi: 10.1242/jeb.168179 Published 19 January 2018

This paper is behind a paywall.

Democratizing science .. neuroscience that is

What is going on with the neuroscience folks? First it was Montreal Neuro opening up its science  as featured in my January 22, 2016 posting,

The Montreal Neurological Institute (MNI) in Québec, Canada, known informally and widely as Montreal Neuro, has ‘opened’ its science research to the world. David Bruggeman tells the story in a Jan. 21, 2016 posting on his Pasco Phronesis blog (Note: Links have been removed),

The Montreal Neurological Institute (MNI) at McGill University announced that it will be the first academic research institute to become what it calls ‘Open Science.’  As Science is reporting, the MNI will make available all research results and research data at the time of publication.  Additionally it will not seek patents on any of the discoveries made on research at the Institute.

Will this catch on?  I have no idea if this particular combination of open access research data and results with no patents will spread to other university research institutes.  But I do believe that those elements will continue to spread.  More universities and federal agencies are pursuing open access options for research they support.  Elon Musk has opted to not pursue patent litigation for any of Tesla Motors’ patents, and has not pursued patents for SpaceX technology (though it has pursued litigation over patents in rocket technology). …

Whether or not they were inspired by the MNI, the scientists at the University of Washington (UW [state]) have found their own unique way of opening up science. From a March 15, 2018 UW news blog posting (also on EurekAlert) by James Urton, Note: Links have been removed,

Over the past few years, scientists have faced a problem: They often cannot reproduce the results of experiments done by themselves or their peers.

This “replication crisis” plagues fields from medicine to physics, and likely has many causes. But one is undoubtedly the difficulty of sharing the vast amounts of data collected and analyses performed in so-called “big data” studies. The volume and complexity of the information also can make these scientific endeavors unwieldy when it comes time for researchers to share their data and findings with peers and the public.

Researchers at the University of Washington have developed a set of tools to make one critical area of big data research — that of our central nervous system — easier to share. In a paper published online March 5 [2018] in Nature Communications, the UW team describes an open-access browser they developed to display, analyze and share neurological data collected through a type of magnetic resonance imaging study known as diffusion-weighted MRI.

“There has been a lot of talk among researchers about the replication crisis,” said lead author Jason Yeatman. “But we wanted a tool — ready, widely available and easy to use — that would actually help fight the replication crisis.”

Yeatman — who is an assistant professor in the UW Department of Speech & Hearing Sciences and the Institute for Learning & Brain Sciences (I-LABS) — is describing AFQ-Browser. This web browser-based tool, freely available online, is a platform for uploading, visualizing, analyzing and sharing diffusion MRI data in a format that is publicly accessible, improving transparency and data-sharing methods for neurological studies. In addition, since it runs in the web browser, AFQ-Browser is portable — requiring no additional software package or equipment beyond a computer and an internet connection.

“One major barrier to data transparency in neuroscience is that so much data collection, storage and analysis occurs on local computers with special software packages,” said senior author Ariel Rokem, a senior data scientist in the UW eScience Institute. “But using AFQ-Browser, we eliminate those requirements and make uploading, sharing and analyzing diffusion-weighted MRI data a simple, straightforward process.”

Diffusion-weighted MRI measures the movement of fluid in the brain and spinal cord, revealing the structure and function of white-matter tracts. These are the connections of the central nervous system, tissue that are made up primarily of axons that transmit long-range signals between neural circuits. Diffusion MRI research on brain connectivity has fundamentally changed the way neuroscientists understand human brain function: The state, organization and layout of white matter tracts are at the core of cognitive functions such as memory, learning and other capabilities. Data collected using diffusion-weighted MRI can be used to diagnose complex neurological conditions such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Researchers also use diffusion-weighted MRI data to study the neurological underpinnings of conditions such as dyslexia and learning disabilities.

“This is a widely-used technique in neuroscience research, and it is particularly amenable to the benefits that can be gleaned from big data, so it became a logical starting point for developing browser-based, open-access tools for the field,” said Yeatman.

The AFQ-Browser — the AFQ stands for Automated Fiber-tract Quantification — can receive diffusion-weighted MRI data and perform tract analysis for each individual subject. The analyses occur via a remote server, again eliminating technical and financial barriers for researchers. The AFQ-Browser also contains interactive tools to display data for multiple subjects — allowing a researcher to easily visualize how white matter tracts might be similar or different among subjects, identify trends in the data and generate hypotheses for future experiments. Researchers also can insert additional code to analyze the data, as well as save, upload and share data instantly with fellow researchers.

“We wanted this tool to be as generalizable as possible, regardless of research goals,” said Rokem. “In addition, the format is easy for scientists from a variety of backgrounds to use and understand — so that neuroscientists, statisticians and other researchers can collaborate, view data and share methods toward greater reproducibility.”

The idea for the AFQ-Browser came out of a UW course on data visualization, and the researchers worked with several graduate students to develop and perfect the browser. They tested it on existing diffusion-weighted MRI datasets, including research subjects with ALS and MS. In the future, they hope that the AFQ-Browser can be improved to do automated analyses — and possibly even diagnoses — based on diffusion-weighted MRI data.

“AFQ-Browser is really just the start of what could be a number of tools for sharing neuroscience data and experiments,” said Yeatman. “Our goal here is greater reproducibility and transparency, and a more robust scientific process.”

Here are a couple of images the researchers have used to illustrate their work,

AFQ-Browser.Jason Yeatman/Ariel Rokem Courtesy: University of Washington

Depiction of the left hemisphere of the human brain. Colored regions are selected white matter regions that could be measured using diffusion-weighted MRI: Corticospinal tract (orange), arcuate fasciculus (blue) and cingulum (green).Jason Yeatman/Ariel Rokem

You can find an embedded version of the AFQ-Browser here: (scroll down about 50 – 55% of the way).

As for the paper, here’s a link and a citation,

A browser-based tool for visualization and analysis of diffusion MRI data by Jason D. Yeatman, Adam Richie-Halford, Josh K. Smith, Anisha Keshavan, & Ariel Rokem. Nature Communicationsvolume 9, Article number: 940 (2018) doi:10.1038/s41467-018-03297-7 Published online: 05 March 2018

Fittingly, this paper is open access.

New wound dressings with nanofibres for tissue regeneration

The Rotary Jet-Spinning manufacturing system was developed specifically as a therapeutic for the wounds of war. The dressings could be a good option for large wounds, such as burns, as well as smaller wounds on the face and hands, where preventing scarring is important. Illustration courtesy of Michael Rosnach/Harvard University

This image really gets the idea of regeneration across to the viewer while also informing you that this is medicine that comes from the military. A March 19,2018 news item on announces the work,

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering have developed new wound dressings that dramatically accelerate healing and improve tissue regeneration. The two different types of nanofiber dressings, described in separate papers, use naturally-occurring proteins in plants and animals to promote healing and regrow tissue.

Our fiber manufacturing system was developed specifically for the purpose of developing therapeutics for the wounds of war,” said Kit Parker, the Tarr Family Professor of Bioengineering and Applied Physics at SEAS and senior author of the research. “As a soldier in Afghanistan, I witnessed horrible wounds and, at times, the healing process for those wounds was a horror unto itself. This research is a years-long effort by many people on my team to help with these problems.”

Parker is also a Core Faculty Member of the Wyss Institute.

The most recent paper, published in Biomaterials, describes a wound dressing inspired by fetal tissue.

A March 19, 2018 Harvard University John A. Paulson School of Engineering and Applied Science news release by Leah Burrows (also on EurekAlert), which originated the news item, provides some background information before launching into more detail about this latest work,

In the late 1970s, when scientists first started studying the wound-healing process early in development, they discovered something unexpected: Wounds incurred before the third trimester left no scars. This opened a range of possibilities for regenerative medicine. But for decades, researchers have struggled to replicate those unique properties of fetal skin.

Unlike adult skin, fetal skin has high levels of a protein called fibronectin, which assembles into the extracellular matrix and promotes cell binding and adhesion. Fibronectin has two structures: globular, which is found in blood, and fibrous, which is found in tissue. Even though fibrous fibronectin holds the most promise for wound healing, previous research focused on the globular structure, in part because manufacturing fibrous fibronectin was a major engineering challenge.

But Parker and his team are pioneers in the field of nanofiber engineering.

The researchers made fibrous fibronectin using a fiber-manufacturing platform called Rotary Jet-Spinning (RJS), developed by Parker’s Disease Biophysics Group. RJS works likes a cotton-candy machine — a liquid polymer solution, in this case globular fibronectin dissolved in a solvent, is loaded into a reservoir and pushed out through a tiny opening by centrifugal force as the device spins. As the solution leaves the reservoir, the solvent evaporates and the polymers solidify. The centrifugal force unfolds the globular protein into small, thin fibers. These fibers — less than one micrometer in diameter — can be collected to form a large-scale wound dressing or bandage.

“The dressing integrates into the wound and acts like an instructive scaffold, recruiting different stem cells that are relevant for regeneration and assisting in the healing process before being absorbed into the body,” said Christophe Chantre, a graduate student in the Disease Biophysics Group and first author of the paper.

In in vivo testing, the researchers found that wounds treated with the fibronectin dressing showed 84 percent tissue restoration within 20 days, compared with 55.6 percent restoration in wounds treated with a standard dressing.

The researchers also demonstrated that wounds treated with the fibronectin dressing had almost normal epidermal thickness and dermal architecture, and even regrew hair follicles — often considered one of the biggest challenges in the field of wound healing.

“This is an important step forward,” said Chantre. “Most work done on skin regeneration to date involves complex treatments combining scaffolds, cells, and even growth factors. Here we were able to demonstrate tissue repair and hair follicle regeneration using an entirely material approach. This has clear advantages for clinical translation.”

In another paper published in Advanced Healthcare Materials, the Disease Biophysics Group demonstrated a soy-based nanofiber that also enhances and promotes wound healing.

Soy protein contains both estrogen-like molecules — which have been shown to accelerate wound healing — and bioactive molecules similar to those that build and support human cells.

“Both the soy- and fibronectin-fiber technologies owe their success to keen observations in reproductive medicine,” said Parker. “During a woman’s cycle, when her estrogen levels go high, a cut will heal faster. If you do a surgery on a baby still in the womb, they have scar-less wound healing. Both of these new technologies are rooted in the most fascinating of all the topics in human biology — how we reproduce.”

In a similar way to fibronectin fibers, the research team used RJS to spin ultrathin soy fibers into wound dressings. In experiments, the soy- and cellulose-based dressing demonstrated a 72 percent increase in healing over wounds with no dressing and a 21 percent increase in healing over wounds dressed without soy protein.

“These findings show the great promise of soy-based nanofibers for wound healing,” said Seungkuk Ahn, a graduate student in the Disease Biophysics Group and first author of the paper. “These one-step, cost-effective scaffolds could be the next generation of regenerative dressings and push the envelope of nanofiber technology and the wound-care market.”

Both kinds of dressing, according to researchers, have advantages in the wound-healing space. The soy-based nanofibers — consisting of cellulose acetate and soy protein hydrolysate — are inexpensive, making them a good option for large-scale use, such as on burns. The fibronectin dressings, on the other hand, could be used for smaller wounds on the face and hands, where preventing scarring is important.

Here’s are links and citations for both papers mentioned in the news release,

Soy Protein/Cellulose Nanofiber Scaffolds Mimicking Skin Extracellular Matrix for Enhanced Wound Healing by Seungkuk Ahn, Christophe O. Chantre, Alanna R. Gannon, Johan U. Lind, Patrick H. Campbell, Thomas Grevesse, Blakely B. O’Connor, Kevin Kit Parker. Advanced Healthcare Materials First published: 23 January 2018

Production-scale fibronectin nanofibers promote wound closure and tissue repair in a dermal mouse model by Christophe O. Chantre, Patrick H. Campbell, Holly M. Golecki, Adrian T. Buganza, Andrew K. Capulli, Leila F. Deravi, Stephanie Dauth, Sean P. Sheehy, Jeffrey A.Paten. KarlGledhill, Yanne S. Doucet, Hasan E.Abaci, Seungkuk Ahn, Benjamin D.Pope, Jeffrey W.Ruberti, Simon P.Hoerstrup, Angela M.Christiano, Kevin Kit Parker. Biomaterials Volume 166, June 2018, Pages 96-108 Available online 5 March 2018

Both papers are behind paywalls although you may want to check with ResearchGate where many researchers make their papers available for free.

One last comment, I noticed this at the end of Burrows’ news release,

The Harvard Office of Technology Development has protected the intellectual property relating to these projects and is exploring commercialization opportunities.

It reminded me of the patent battle between the Broad Institute (a Harvard University and Massachusetts Institute of Technology joint venture) and the University of California at Berkeley over CRISPR (clustered regularly interspaced short palindromic repeats) technology. (My March 15, 2017 posting describes the battle’s outcome.)

Lest we forget, there could be major financial rewards from this work.

Emergency!!! Lonely heart looking for love: Female. Stocky build. Height of 2 – 3 inches.

(Matias Careaga) [downloaded from]

That is a very soulful look. How could any female Sehuencas water frog resist it? Sadly, that’s the problem. They havn’t found any female Sehuencas water frogs yet.

It’s not for want of trying. Back in February 2018 worldwide interest was raised when scientists as the Cochabamba Natural History Museum (Bolivia) started a campaign to find a mate and raise funds for a search. ( I don’t know how I missed this story the first time. For long time readers, this is my frog story for this year.)  From a February 14, 2018 article by Anoop Menon for,

Scientists are scouring for a mate for Romeo, who has been calling forth for mates for the last nine years now. But alas, a mate hasn’t been found in the rivers and streams of the Sehuencas water frog’s natural habitat so far. So scientists have decided to make a profile for the lovelorn frog, according to the BBC [British Broadcasting Corporation]. The effort hopes to raise awareness of the condition of the Sehuencas water frog and raise money to fund searches for the Sehuencas water frog in areas where they once thrived.

Romeo’s dating profile reads, “I’m a pretty simple guy. I tend to keep to myself and have the best nights just chilling at home, maybe binge-watching the waters around me. I do love food, though, and will throw a pair of pants on and get out of the house if there’s a worm or snail to be eaten!” His preference is for females between two to three inches tall and is okay with drinkers but not smokers. But honestly, at this point, he should be fine with just about anything.

All jokes aside, Romeo’s plight is an important one. The profile links to the campaign donation page that it is part of, with an aim of raising USD 15,000 to search for more Sehuencas water frogs. And is doing its part by matching all donations made from February 9 to today, Valentine’s Day.

Zoe Schlanger’s February 10, 2018 article for Quartz, in the context of Romeo’s (and the scientists’) quest, offers information about the ‘current state of amphibia’, Note: Links have been removed)

As the Earth faces what some experts call its “sixth mass extinction,” amphibians, like frogs, are among the most imperiled. Around half of amphibian species (which includes toads, salamanders, frogs, and newts) are reported to be in decline. A third are considered to be threatened with extinction.

Last year, 10,000 critically endangered “scrotum frogs” that lived in Lake Titicaca on the border between Bolivia and Peru died en masse. In the US, federal scientists say the overall amphibian population is shrinking in size by 3.8% every year. That trend has continued since the 1960s, due to a mix of climate change, pesticide applications, and diseases like infectious fungi which can quickly decimate populations.

Frogs seem to be especially vulnerable. Roughly 74% of frog species globally are in decline, and 80% of the frog species that live in India are threatened, a researcher recently told the Hindustan Times.

Hande ‘s February 12, 2018 article for CNN adds a few more details about Romeo and about the effort to save him,

Arturo Munoz [Arturo Muñoz Saravia] , founder of the Bolivian Amphibian Initiative and GWC [Global Wildlife Conservaation] associate conservation scientist, said, “When biologists collected Romeo 10 years ago, we knew the Sehuencas water frog, like other amphibians in Bolivia, was in trouble, but we had no idea we wouldn’t be able to find a single other individual in all this time.”

Romeo started to call for a mate about a year after he was brought into captivity and Munoz pointed out that those calls have slowed in the last few years.

“We don’t want him to lose hope, and we continue to remain hopeful that others are out there, so we can establish a conservation breeding program to save this species,” Munoz said.


They raised almost $25,000 in funds to search for a female but there’s been no luck yet. Sehuencas water frogs live for about 15 years and Romeo has lived in the Cochabamba Natural History Museum for the last nine or 10 years. You do the arithmetic.

Apparently, Sehuencas water frogs were once found in both Ecuador and Bolivia. Today, there are only two regions of Bolivia (Cochabamba and Santa Cruz) where they are reputed to live. (There is more about the current search for a mate in a July 26, 2018 news item on Sehuencas water frog Wikipedia entry has this to say (Note: Links have been removed),

While it is currently listed as vulnerable by the IUCN [International Union for Conservation of Nature], this is based on an assessment that has not been updated since 2004.[1] No individuals have been encountered in the wild since 2008.

You can find out more about Muñoz’s Bolivian Amphibian Initiative here. There don’t seem to be any Romeo updates on the website but they still seem to be gathering donations. Romeo’s dating profile is here.


One possibility occurred to me (and I imagine others), if there’s someone out there who has a female Sehuencas water frog in their aquarium at home, please consider saving the species. I’m certain a deal can be made.

Finally,. Good luck, Romeo!

The mystifying physics of paint-on semiconductors

I was not expecting a Canadian connection but it seems we are heavily invested in this research at the Georgia Institute of Technology (Georgia Tech), from a March 19, 2018 news item on ScienceDaily,

Some novel materials that sound too good to be true turn out to be true and good. An emergent class of semiconductors, which could affordably light up our future with nuanced colors emanating from lasers, lamps, and even window glass, could be the latest example.

These materials are very radiant, easy to process from solution, and energy-efficient. The nagging question of whether hybrid organic-inorganic perovskites (HOIPs) could really work just received a very affirmative answer in a new international study led by physical chemists at the Georgia Institute of Technology.

A March 19,. 2018 Georgia Tech news release (also on EurekAlert), which originated the news item, provides more detail,

The researchers observed in an HOIP a “richness” of semiconducting physics created by what could be described as electrons dancing on chemical underpinnings that wobble like a funhouse floor in an earthquake. That bucks conventional wisdom because established semiconductors rely upon rigidly stable chemical foundations, that is to say, quieter molecular frameworks, to produce the desired quantum properties.

“We don’t know yet how it works to have these stable quantum properties in this intense molecular motion,” said first author Felix Thouin, a graduate research assistant at Georgia Tech. “It defies physics models we have to try to explain it. It’s like we need some new physics.”

Quantum properties surprise

Their gyrating jumbles have made HOIPs challenging to examine, but the team of researchers from a total of five research institutes in four countries succeeded in measuring a prototypical HOIP and found its quantum properties on par with those of established, molecularly rigid semiconductors, many of which are graphene-based.

“The properties were at least as good as in those materials and may be even better,” said Carlos Silva, a professor in Georgia Tech’s School of Chemistry and Biochemistry. Not all semiconductors also absorb and emit light well, but HOIPs do, making them optoelectronic and thus potentially useful in lasers, LEDs, other lighting applications, and also in photovoltaics.

The lack of molecular-level rigidity in HOIPs also plays into them being more flexibly produced and applied.

Silva co-led the study with physicist Ajay Ram Srimath Kandada. Their team published the results of their study on two-dimensional HOIPs on March 8, 2018, in the journal Physical Review Materials. Their research was funded by EU Horizon 2020, the Natural Sciences and Engineering Research Council of Canada, the Fond Québécois pour la Recherche, the [National] Research Council of Canada, and the National Research Foundation of Singapore. [emphases mine]

The ‘solution solution’

Commonly, semiconducting properties arise from static crystalline lattices of neatly interconnected atoms. In silicon, for example, which is used in most commercial solar cells, they are interconnected silicon atoms. The same principle applies to graphene-like semiconductors.

“These lattices are structurally not very complex,” Silva said. “They’re only one atom thin, and they have strict two-dimensional properties, so they’re much more rigid.”

“You forcefully limit these systems to two dimensions,” said Srimath Kandada, who is a Marie Curie International Fellow at Georgia Tech and the Italian Institute of Technology. “The atoms are arranged in infinitely expansive, flat sheets, and then these very interesting and desirable optoelectronic properties emerge.”

These proven materials impress. So, why pursue HOIPs, except to explore their baffling physics? Because they may be more practical in important ways.

“One of the compelling advantages is that they’re all made using low-temperature processing from solutions,” Silva said. “It takes much less energy to make them.”

By contrast, graphene-based materials are produced at high temperatures in small amounts that can be tedious to work with. “With this stuff (HOIPs), you can make big batches in solution and coat a whole window with it if you want to,” Silva said.

Funhouse in an earthquake

For all an HOIP’s wobbling, it’s also a very ordered lattice with its own kind of rigidity, though less limiting than in the customary two-dimensional materials.

“It’s not just a single layer,” Srimath Kandada said. “There is a very specific perovskite-like geometry.” Perovskite refers to the shape of an HOIPs crystal lattice, which is a layered scaffolding.

“The lattice self-assembles,” Srimath Kandada said, “and it does so in a three-dimensional stack made of layers of two-dimensional sheets. But HOIPs still preserve those desirable 2D quantum properties.”

Those sheets are held together by interspersed layers of another molecular structure that is a bit like a sheet of rubber bands. That makes the scaffolding wiggle like a funhouse floor.

“At room temperature, the molecules wiggle all over the place. That disrupts the lattice, which is where the electrons live. It’s really intense,” Silva said. “But surprisingly, the quantum properties are still really stable.”

Having quantum properties work at room temperature without requiring ultra-cooling is important for practical use as a semiconductor.

Going back to what HOIP stands for — hybrid organic-inorganic perovskites – this is how the experimental material fit into the HOIP chemical class: It was a hybrid of inorganic layers of a lead iodide (the rigid part) separated by organic layers (the rubber band-like parts) of phenylethylammonium (chemical formula (PEA)2PbI4).

The lead in this prototypical material could be swapped out for a metal safer for humans to handle before the development of an applicable material.

Electron choreography

HOIPs are great semiconductors because their electrons do an acrobatic square dance.

Usually, electrons live in an orbit around the nucleus of an atom or are shared by atoms in a chemical bond. But HOIP chemical lattices, like all semiconductors, are configured to share electrons more broadly.

Energy levels in a system can free the electrons to run around and participate in things like the flow of electricity and heat. The orbits, which are then empty, are called electron holes, and they want the electrons back.

“The hole is thought of as a positive charge, and of course, the electron has a negative charge,” Silva said. “So, hole and electron attract each other.”

The electrons and holes race around each other like dance partners pairing up to what physicists call an “exciton.” Excitons act and look a lot like particles themselves, though they’re not really particles.

Hopping biexciton light

In semiconductors, millions of excitons are correlated, or choreographed, with each other, which makes for desirable properties, when an energy source like electricity or laser light is applied. Additionally, excitons can pair up to form biexcitons, boosting the semiconductor’s energetic properties.

“In this material, we found that the biexciton binding energies were high,” Silva said. “That’s why we want to put this into lasers because the energy you input ends up to 80 or 90 percent as biexcitons.”

Biexcitons bump up energetically to absorb input energy. Then they contract energetically and pump out light. That would work not only in lasers but also in LEDs or other surfaces using the optoelectronic material.

“You can adjust the chemistry (of HOIPs) to control the width between biexciton states, and that controls the wavelength of the light given off,” Silva said. “And the adjustment can be very fine to give you any wavelength of light.”

That translates into any color of light the heart desires.


Coauthors of this paper were Stefanie Neutzner and Annamaria Petrozza from the Italian Institute of Technology (IIT); Daniele Cortecchia from IIT and Nanyang Technological University (NTU), Singapore; Cesare Soci from the Centre for Disruptive Photonic Technologies, Singapore; Teddy Salim and Yeng Ming Lam from NTU; and Vlad Dragomir and Richard Leonelli from the University of Montreal. …

Three Canadian science funding agencies plus European and Singaporean science funding agencies but not one from the US ? That’s a bit unusual for research undertaken at a US educational institution.

In any event, here’s a link to and a citation for the paper,

Stable biexcitons in two-dimensional metal-halide perovskites with strong dynamic lattice disorder by Félix Thouin, Stefanie Neutzner, Daniele Cortecchia, Vlad Alexandru Dragomir, Cesare Soci, Teddy Salim, Yeng Ming Lam, Richard Leonelli, Annamaria Petrozza, Ajay Ram Srimath Kandada, and Carlos Silva. Phys. Rev. Materials 2, 034001 – Published 8 March 2018

This paper is behind a paywall.

Better motor control for prosthetic hands (the illusion of feeling) and a discussion of superprostheses and reality

I have two bits about prosthetics, one which focuses on how most of us think of them and another about science fiction fantasies.

Better motor control

This new technology comes via a collaboration between the University of Alberta, the University of New Brunswick (UNB) and Ohio’s Cleveland Clinic, from a March 18, 2018 article by Nicole Ireland for the Canadian Broadcasting Corporation’s (CBC) news online,

Rob Anderson was fighting wildfires in Alberta when the helicopter he was in crashed into the side of a mountain. He survived, but lost his left arm and left leg.

More than 10 years after that accident, Anderson, now 39, says prosthetic limb technology has come a long way, and he feels fortunate to be using “top of the line stuff” to help him function as normally as possible. In fact, he continues to work for the Alberta government’s wildfire fighting service.

His powered prosthetic hand can do basic functions like opening and closing, but he doesn’t feel connected to it — and has limited ability to perform more intricate movements with it, such as shaking hands or holding a glass.

Anderson, who lives in Grande Prairie, Alta., compares its function to “doing things with a long pair of pliers.”

“There’s a disconnect between what you’re physically touching and what your body is doing,” he told CBC News.

Anderson is one of four Canadian participants in a study that suggests there’s a way to change that. …

Six people, all of whom had arm amputations from below the elbow or higher, took part in the research. It found that strategically placed vibrating “robots” made them “feel” the movements of their prosthetic hands, allowing them to grasp and grip objects with much more control and accuracy.

All of the participants had all previously undergone a specialized surgical procedure called “targeted re-innervation.” The nerves that had connected to their hands before they were amputated were rewired to link instead to muscles (including the biceps and triceps) in their remaining upper arms and in their chests.

For the study, researchers placed the robotic devices on the skin over those re-innervated muscles and vibrated them as the participants opened, closed, grasped or pinched with their prosthetic hands.

While the vibration was turned on, the participants “felt” their artificial hands moving and could adjust their grip based on the sensation. …

I have an April 24, 2017 posting about a tetraplegic patient who had a number of electrodes implanted in his arms and hands linked to a brain-machine interface and which allowed him to move his hands and arms; the implants were later removed. It is a different problem with a correspondingly different technological solution but there does seem to be increased interest in implanting sensors and electrodes into the human body to increase mobility and/or sensation.

Anderson describes how it ‘feels,

“It was kind of surreal,” Anderson said. “I could visually see the hand go out, I would touch something, I would squeeze it and my phantom hand felt like it was being closed and squeezing on something and it was sending the message back to my brain.

“It was a very strange sensation to actually be able to feel that feedback because I hadn’t in 10 years.”

The feeling of movement in the prosthetic hand is an illusion, the researchers say, since the vibration is actually happening to a muscle elsewhere in the body. But the sensation appeared to have a real effect on the participants.

“They were able to control their grasp function and how much they were opening the hand, to the same degree that someone with an intact hand would,” said study co-author Dr. Jacqueline Hebert, an associate professor in the Faculty of Rehabilitation Medicine at the University of Alberta.

Although the researchers are encouraged by the study findings, they acknowledge that there was a small number of participants, who all had access to the specialized re-innervation surgery to redirect the nerves from their amputated hands to other parts of their body.

The next step, they say, is to see if they can also simulate the feeling of movement in a broader range of people who have had other types of amputations, including legs, and have not had the re-innervation surgery.

Here’s a March 15, 2018  CBC New Brunswick radio interview about the work,

This is a bit longer than most of the embedded audio pieces that I have here but it’s worth it. Sadly, I can’t identify the interviewer who did a very good job with Jon Sensinger, associate director of UNB’s Institute of Biomedical Engineering. One more thing, I noticed that the interviewer made no mention of the University of Alberta in her introduction or in the subsequent interview. I gather regionalism reigns supreme everywhere in Canada. Or, maybe she and Sensinger just forgot. It happens when you’re excited. Also, there were US institutions in Ohio and Virginia that participated in this work.

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

Illusory movement perception improves motor control for prosthetic hands by Paul D. Marasco, Jacqueline S. Hebert, Jon W. Sensinger, Courtney E. Shell, Jonathon S. Schofield, Zachary C. Thumser, Raviraj Nataraj, Dylan T. Beckler, Michael R. Dawson, Dan H. Blustein, Satinder Gill, Brett D. Mensh, Rafael Granja-Vazquez, Madeline D. Newcomb, Jason P. Carey, and Beth M. Orzell. Science Translational Medicine 14 Mar 2018: Vol. 10, Issue 432, eaao6990 DOI: 10.1126/scitranslmed.aao6990

This paper is open access.

Superprostheses and our science fiction future

A March 20, 2018 news item on features an essay on about superprostheses and/or assistive devices,

Assistive devices may soon allow people to perform virtually superhuman feats. According to Robert Riener, however, there are more pressing goals than developing superhumans.

What had until recently been described as a futuristic vision has become a reality: the first self-declared “cyborgs” have had chips implanted in their bodies so that they can open doors and make cashless payments. The latest robotic hand prostheses succeed in performing all kinds of grips and tasks requiring dexterity. Parathletes fitted with running and spring prostheses compete – and win – against the best, non-impaired athletes. Then there are robotic pets and talking humanoid robots adding a bit of excitement to nursing homes.

Some media are even predicting that these high-tech creations will bring about forms of physiological augmentation overshadowing humans’ physical capabilities in ways never seen before. For instance, hearing aids are eventually expected to offer the ultimate in hearing; retinal implants will enable vision with a sharpness rivalling that of any eagle; motorised exoskeletons will transform soldiers into tireless fighting machines.

Visions of the future: the video game Deus Ex: Human Revolution highlights the emergence of physiological augmentation. (Visualisations: Square Enix) Courtesy: ETH Zurich

Professor Robert Riener uses the image above to illustrate the notion of superprosthese in his March 20, 2018 essay on the ETH Zurich website,

All of these prophecies notwithstanding, our robotic transformation into superheroes will not be happening in the immediate future and can still be filed under Hollywood hero myths. Compared to the technology available today, our bodies are a true marvel whose complexity and performance allows us to perform an extremely wide spectrum of tasks. Hundreds of efficient muscles, thousands of independently operating motor units along with millions of sensory receptors and billions of nerve cells allow us to perform delicate and detailed tasks with tweezers or lift heavy loads. Added to this, our musculoskeletal system is highly adaptable, can partly repair itself and requires only minimal amounts of energy in the form of relatively small amounts of food consumed.

Machines will not be able to match this any time soon. Today’s assistive devices are still laboratory experiments or niche products designed for very specific tasks. Markus Rehm, an athlete with a disability, does not use his innovative spring prosthesis to go for walks or drive a car. Nor can today’s conventional arm prostheses help a person tie their shoes or button up their shirt. Lifting devices used for nursing care are not suitable for helping with personal hygiene tasks or in psychotherapy. And robotic pets quickly lose their charm the moment their batteries die.

Solving real problems

There is no denying that advances continue to be made. Since the scientific and industrial revolutions, we have become dependent on relentless progress and growth, and we can no longer separate today’s world from this development. There are, however, more pressing issues to be solved than creating superhumans.

On the one hand, engineers need to dedicate their efforts to solving the real problems of patients, the elderly and people with disabilities. Better technical solutions are needed to help them lead normal lives and assist them in their work. We need motorised prostheses that also work in the rain and wheelchairs that can manoeuvre even with snow on the ground. Talking robotic nurses also need to be understood by hard-of-hearing pensioners as well as offer simple and dependable interactivity. Their batteries need to last at least one full day to be recharged overnight.

In addition, financial resources need to be available so that all people have access to the latest technologies, such as a high-quality household prosthesis for the family man, an extra prosthesis for the avid athlete or a prosthesis for the pensioner. [emphasis mine]

Breaking down barriers

What is just as important as the ongoing development of prostheses and assistive devices is the ability to minimise or eliminate physical barriers. Where there are no stairs, there is no need for elaborate special solutions like stair lifts or stairclimbing wheelchairs – or, presumably, fully motorised exoskeletons.

Efforts also need to be made to transform the way society thinks about people with disabilities. More acknowledgement of the day-to-day challenges facing patients with disabilities is needed, which requires that people be confronted with the topic of disability when they are still children. Such projects must be promoted at home and in schools so that living with impairments can also attain a state of normality and all people can partake in society. It is therefore also necessary to break down mental barriers.

The road to a virtually superhuman existence is still far and long. Anyone reading this text will not live to see it. In the meantime, the task at hand is to tackle the mundane challenges in order to simplify people’s daily lives in ways that do not require technology, that allow people to be active participants and improve their quality of life – instead of wasting our time getting caught up in cyborg euphoria and digital mania.

I’m struck by Riener’s reference to financial resources and access. Sensinger mentions financial resources in his CBC radio interview although his concern is with convincing funders that prostheses that mimic ‘feeling’ are needed.

I’m also struck by Riener’s discussion about nontechnological solutions for including people with all kinds of abilities and disabilities.

There was no grand plan for combining these two news bits; I just thought they were interesting together.

Café Scientifique Vancouver (Canada) talk on July 31st. 2018: Test Tubes to Teaching: How Anti-Vaxxers and a Global Financial Crisis Shaped my Career

I received (via email) this Café Scientifique July 15, 2018 notice ,

Our next café will happen on TUESDAY, JULY 31ST at 7:30PM in the back
room at YAGGER’S DOWNTOWN (433 W Pender). Our speaker for the
SCIENCES AT SFU. Her topic will be:


Part research talk, and part memoir, Dr. van Houten will describe her
career progression from vaccine design scientist to education
researcher. From early childhood, Dr. van Houten developed an
unrelenting interest in human biology and infectious diseases and made
it her goal to become a scientist. Her passion for vaccines came about,
in part, due to the publicity surrounding the infamous retracted paper
in _The Lancet_ that erroneously connected measles vaccination with
autism. Her Ph.D. and postdoctoral research focused on how vaccines
work, and she engineered anti-viral vaccines to produce focused antibody
responses. However, her plan of working in the pharmaceutical industry
was sidelined by the financial crash of 2008, and she was offered a full
time teaching faculty position. This created an opportunity to study how
students think critically about science and apply those findings to
train students to recognize bad science such as that promoted by
anti-vaxxers and other garbage “science” that pervades our society.

We hope to see you there!

I wasn’t able to find out much more about Dr. van Houten and her work but her SFU profile page is here.

Panning for silver nanoparticles in your clothes washer

A March 20, 2018 news item on describes a new approach to treating wastewater (Note: Links have been removed),

Humans have known since ancient times that silver kills or stops the growth of many microorganisms. Hippocrates, the father of medicine, is said to have used silver preparations for treating ulcers and healing wounds. Until the introduction of antibiotics in the 1940s, colloidal silver (tiny particles suspended in a liquid) was a mainstay for treating burns, infected wounds and ulcers. Silver is still used today in wound dressings, in creams and as a coating on medical devices.

Since the 1990s, manufacturers have added silver nanoparticles to numerous consumer products to enhance their antibacterial and anti-odor properties. Examples include clothes, towels, undergarments, socks, toothpaste and soft toys. Nanoparticles are ultra-small particles, ranging from 1 to 100 nanometers in diameter – too small to see even with a microscope. According to a widely cited database, about one-fourth of nanomaterial-based consumer products currently marketed in the United States contain nanosilver.

Multiple studies have reported that nanosilver leaches out of textiles when they are laundered. Research also reveals that nanosilver may be toxic to humans and aquatic and marine organisms. Although it is widely used, little is understood about its fate or long-term toxic effects in the environment.

We are developing ways to convert this potential ecological crisis into an opportunity by recovering pure silver nanoparticles, which have many industrial applications, from laundry wastewater. In a recently published study, we describe a technique for silver recovery and discuss the key technical challenges. Our approach tackles this problem at the source – in this case, individual washing machines. We believe that this strategy has great promise for getting newly identified contaminants out of wastewater.

A March 20, 2018 essay by Sukalyan Sengupta, Professor of Wastewater Treatment, and Tabish Nawaz. Doctoral Student, both at University of Massachusetts at Dartmouth on The Conversation website, which originated the news item, expands on the theme (Note: Links have been removed),

Use of nanosilver in consumer products has steadily risen in the past decade. The market share of silver-based textiles rose from 9 percent in 2004 to 25 percent in 2011.

Several investigators have measured the silver content of textiles and found values ranging from 0.009 to 21,600 milligrams of silver per kilogram of textile. Studies show that the amount of silver leached in the wash solution depends on many factors, including interactions between detergent and other chemicals and how silver is attached to the textiles.

In humans, exposure to silver can harm liver cells, skin and lungs. Prolonged exposure or exposure to a large dose can cause a condition called Argyria, in which the victim’s skin turns permanently bluish-gray.

Once silver goes down the drain and ends up at wastewater treatment plants, it can potentially harm bacterial treatment processes, making them less efficient, and foul treatment equipment. More than 90 percent of silver nanoparticles released in wastewater end up in nutrient-rich biosolids left over at the end of sewage treatment, which often are used on land as agricultural fertilizers.

Silver is toxic in aquatic environments, a concern that’s becoming more serious with the increased use of silver nanoparticles and awareness that oceans, rivers, and lakes are dangerously stressed.

Sengupta and Nawaz go on to describe their proposed solution (Note: Links have been removed),

Our research shows that the most efficient way to remove silver from wastewater is by treating it in the washing machine. At this point silver concentrations are relatively high, and silver is initially released from treated clothing in a chemical form that is feasible to recover.

A bit of chemistry is helpful here. Our recovery method employs a widely used chemistry process called ion exchange. Ions are atoms or molecules that have an electrical charge. In ion exchange, a solid and a liquid are brought together and exchange ions with each other.

For example, household soaps do not lather well in “hard” water, which contains high levels of ions such as magnesium and calcium. Many home water filters use ion exchange to “soften” the water, replacing those materials with other ions that do not affect its properties in the same way.

For this process to work, the ions that switch places must both be either positively or negatively charged. Nanosilver is initially released from textiles as silver ion, which is a cation – an ion with a positive charge (hence the plus sign in its chemical symbol, Ag+).

Even at the source, removing silver from washwater is challenging. Silver concentrations in the wash solution are relatively low compared to other cations, such as calcium, that could interfere with the removal process. Detergent chemistry complicates the picture further because some detergent components can potentially interact with silver.

To recover silver without picking up other chemicals, the recovery process must use materials that have a chemical affinity for silver. In a previous study, we described a potential solution: Using ion-exchange materials embedded with sulfur-based chemicals, which bind preferentially with silver.

In our new study, we passed washwater through an ion-exchange resin column and analyzed how each major detergent ingredient interacted with silver in the water and affected the resin’s ability to remove silver from the water. By manipulating process conditions such as pH, temperature and concentration of nonsilver cations, we were able to identify conditions that maximized silver recovery.

We found that pH and the levels of calcium ions (Ca2+) were critical factors. Higher levels of hydrogen or calcium ions bind up detergent ingredients and prevent them from interacting with silver ions, so the ion-exchange resin can remove the silver from the solution. We also found that some detergent ingredients – particularly bleaching and water-softening agents – made the ion-exchange resin work less efficiently. Depending on these conditions, we recovered between 20 percent and 99 percent of the silver in the washwater.

The researchers go on to propose a new approach to treating wastewater (Note: A link has been removed),

Today wastewater is collected from multiple sources, such as homes and businesses, and piped over long distances to centralized wastewater treatment plants. But increasing evidence shows that these facilities are ill-equipped to keep newly identified contaminants out of the environment, since they use one common treatment scheme for many different waste streams.

We believe the future is in decentralized systems that can treat different types of wastewater with specific technologies designed specifically for the materials they contain. If wastewater from laundromats contains different contaminants than wastewater from restaurants, why treat them the same way?

Interesting, non? In any event, here’s a link to and a citation for what I believe is the researchers’ latest paper on this subject,

Silver Recovery from Laundry Washwater: The Role of Detergent Chemistry by Tabish Nawaz and Sukalyan Sengupta. ACS Sustainable Chem. Eng., 2018, 6 (1), pp 600–608 DOI: 10.1021/acssuschemeng.7b02933 Publication Date (Web): November 21, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall. For anyone who can’t get access, Karla Lant provides a bit more technical detail about the work in her February 2, 2018 article for

In-home (one day in the future) eyesight correction

It’s easy to become blasé about ‘futuristic’ developments but every once in a while something comes along that shocks you out of your complacency as this March 8, 2018 news item did for me,

A revolutionary, cutting-edge technology, developed by researchers at Bar-Ilan University’s Institute of Nanotechnology and Advanced Materials (BINA), has the potential to provide a new alternative to eyeglasses, contact lenses, and laser correction for refractive errors.

The technology, known as Nano-Drops, was developed by opthamologist Dr. David Smadja from Shaare Zedek Medical Center, Prof. Zeev Zalevsky from Bar-Ilan’s Kofkin Faculty of Engineering, and Prof. Jean-Paul Moshe Lellouche, head of the Department of Chemistry at Bar-Ilan.

It seems like it would be eye drops, eh? This March 8, 2018 Bar-Ilan University press release, which originated the news item, proceeds to redefine eyedrops,

Nano-Drops achieve their optical effect and correction by locally modifying the corneal refractive index. The magnitude and nature of the optical correction is adjusted by an optical pattern that is stamped onto the superficial layer of the corneal epithelium with a laser source. The shape of the optical pattern can be adjusted for correction of myopia (nearsightedness), hyperopia (farsightedness) or presbyopia (loss of accommodation ability). The laser stamping onto the cornea [emphasis mine] takes a few milliseconds and enables the nanoparticles to enhance and ‘activate’ this optical pattern by locally changing the refractive index and ultimately modifying the trajectory of light passing through the cornea.

The laser stamping source does not relate to the commonly known ‘laser treatment for visual correction’ that ablates corneal tissue. It is rather a small laser device that can connect to a smartphone [emphasis mine] and stamp the optical pattern onto the corneal epithelium by placing numerous adjacent pulses in a very speedy and painless fashion.  Tiny corneal spots created by the laser allow synthetic and biocompatible nanoparticles to enter and locally modify the optical power of the eye [emphasis mine] at the desired correction.

In the future this technology may enable patients to have their vision corrected in the comfort of their own home. [emphasis mine] To accomplish this, they would open an application on their smartphone to measure their vision, connect the laser source device for stamping the optical pattern at the desired correction, and then apply the Nano-Drops to activate the pattern and provide the desired correction.

Upcoming in-vivo experiments in rabbits will allow the researchers to determine how long the effect of the Nano-Drops will last after the initial application. Meanwhile, this promising technology has been shown, through ex-vivo experiments, to efficiently correct nearly 3 diopters of both myopia and presbyopia in pig eyes.

The researchers do not seem to have published a paper about this work. However, there is a March 19, 2018 article by Shoshanna Solomon for the Times of Israel, which provides greater  detail about how you or I would use this technology,

The Israeli researchers came up with a way to reshape the cornea, which accounts for 60 percent of the eye’s optical power. They tried out their system on the eyes of dead pigs, which have an optical system that is very similar to that of humans.

There are three steps to the technology that is now in development.

The first step requires patients to measure their eyesight via their smartphones. There are already a number of apps that do this, said Smadja. The second step requires the patients to use a second app — being developed by the researchers — which would have a laser device clipped onto the smartphone. This device will deliver laser pulses to the eye in less than a second that etch a shallow shape onto the cornea to help correct its refractive error. During the last stage, the Nano-Drops — made up of nontoxic nanoparticles of proteins — are put into the eye and they activate the shape, thus correcting the patients’ vision.

“It’s like when you write something with fuel on the ground and the fuel dries up, and then you throw a flame onto the fuel and the fire takes the shape of the writing,” Smadja explained. “The drops activate the pattern.”

The technology, unlike current laser operations that correct eyesight, does not remove tissue and is thus noninvasive, and it suits most eyes, expanding the scope of patients who can correct their vision, he said.

It’s a good article and, if you have the time, it’s worth reading in its entirety. Of course, it’s a long from ‘being in development’ to ‘available at the store’.